PLASTICS MATERIAL TESTING - A TEXT AND LABSHEET BOOK

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ii AZIMAH / JUNAIDAH PLASTICS MATERIAL TESTING A TEXT AND LABSHEET BOOK POLITEKNIK SULTAN ABDUL HALIM MU’ADZAM SHAH BANDAR DARULAMAN, 06000 JITRA, KEDAH TEL: 04 - 9146100 FAX: 04 – 9174232 http://www.polimas.edu.my Hakcipta terpelihara Setiap bahagian daripada terbitan ini tidak boleh diterbitkan semula, disimpan untuk pengeluaran atau dipindahkan dalam bentuk lain, samada cara elektronik, mekanik, fotokopi, gambar, rakaman dan sebagainya tanpa mendapat kebenaran bertulis. Penerbit Politeknik Sultan Abdul Halim Mu’adzam Shah 2021

iii POLIMAS POLITEKNIK SULTAN ABDUL HALIM MU’ADZAM SHAH Editor’s Preface This short volume is intended as a text and lab sheet book for students in the plastics program. It is hoped that this book will find use in educational programs for students dedicated to this purpose. The principal objective of Plastics Material Testing is to introduce lab testing of plastics to a broad cross section of students/readers who have need to gain, improve, or refresh their knowledge of plastics testing. The text emphasizes the fundamentals of plastics material testing and their’s properties. Azimah binti Ismail Junaidah binti Ramli

iv Acknowledgments In the name of Allah, the Most Gracious and the Most Merciful. First and foremost, I would like to thank Allah s.w.t for giving me the strengths and His blessing in completing this book. Alhamdulillah, all praises to Allah. Special appreciation goes to my partner Pn Junaidah binti Ramli for her contributions. I also appreciate the encouragement and understanding given by my lovely husband, sons and parents during the writing of this book. APABILA MATI ANAK ADAM MAKA TERPUTUSLAH AMALANNYA KECUALI TIGA PERKARA .. Dari Abu Hurairah r.a. bahawa Nabi Muhammad s.a.w bersabda: "Apabila seorang anak Adam mati putuslah amalnya kecuali tiga perkara : sedekah jariah,ATAU ILMU YANG MEMBERI MANFAAT KEPADA ORANG LAIN atau anak yang soleh yang berdoa untuknya." (Hadith Sahih - Riwayat Muslim dan lain-lainnya)

v CONTENTS PAGE CHAPTER 1 TESTING STANDARDS AND AGENCIES 1.0 Introduction 1.1 American Society for Testing and Materials (ASTM) 1.2 International Organization for Standardization (ISO) 1.3 American National Standards Institute (ANSI) 1.4 Deutsches Institut für Normung (DIN) 1.5 British Standards (BS) 1.6 European Standards 1.7 Japanese Industrial Standards (JIS) 1.8 Malaysian Standards 1 1 2 6 8 10 12 14 16 CHAPTER 2 MECHANICAL PROPERTIES 2.0 Introduction 2.1 Tensile Strength and Tensile Stress 2.2 Compressive 2.3 Shear 2.4 Impact 2.5 Flexural 2.6 Hardness 19 19 24 29 30 35 37

vi CHAPTER 3 PHYSICAL PROPERTIES 3.0 Introduction 3.1 Density 3.2 Relative Density 3.3 Mould Shrinkage 3.4 Tensile Creep 43 43 45 47 49 CHAPTER 4 THERMAL PROPERTIES 4.0 Introduction 4.1 Thermal Conductivity 4.2 Deflection Temperature 4.3 Ablative Plastics 4.4 Flammability 4.5 Melt Flow Index 4.6 Glass Transition Temperature and Softening Point 4.7 Thermal Diffusivity 4.8 Specific Heat 4.9 Melting Point 4.10 Glass Transition Temperature 4.11 Thermal Expansion Coefficient 4.12 Thermal Shock Resistance 4.13 Creep Resistance 51 51 51 53 53 54 55 56 57 57 57 58 58 58

vii CHAPTER 5 ENVIROMENTAL PROPERTIES 5.1 Chemical Properties 5.2 Weathering 5.3 Water Absorption 5.4 Stress Cracking 60 62 63 64 CHAPTER 6 OPTICAL AND ELECTRICAL PROPERTIES 6.1 Optical Properties 6.2 Transparency 6.3 Colour and Infrared Absorption 6.4 Index of Refraction and Dielectric Resistance LAB SHEET MANUAL REFERENCES APPENDICES 65 65 66 67 68 105 106

1 CHAPTER 1 TESTING STANDARDS AND AGENCIES 1.0 Introduction Plastics materials testing, measurement of the characteristics and behaviour plastics under various conditions. The data thus obtained can be used in specifying the suitability of materials for various applications—e.g., building or aircraft construction, machinery, or packaging. A full- or small-scale model of a proposed machine or structure may be tested. Alternatively, investigators may construct mathematical models that utilize known material characteristics and behaviour to predict capabilities of the structure. This chapter will discuss the testing standards and agencies. Several national and international agencies establish and publish testing specifications for industrial materials. In the United States, the standards generally come from the American National Standard Institutes, the United States military services, and the American Society for Testing and Materials (ASTM). A major international organization similar to the ASTM is the International Organization for Standardization (ISO). In Malaysia, for plastics testing also use this two standard. 1.1 American Society for Testing and Materials (ASTM) ASTM SYMBOL What is ASTM? The ASTM is an international, nonprofit technical society devoted to”….the promotion of knowledge of the materials of engineering and the standardization of specifications and methods of testing . The ASTM publishes testing for specifications for most industrial materials. Plastics testing comes under the jurisdiction of the ASTM Committee D on plastics. The ASTM annually publishes the Book Of ASTM Standards annually which includes approximately 15 volumes. Most volumes consists of several sections, each one bound separately. A full set of ASTM standards amounts to about 70 sections. The three sections comprising volume 8 deal with plastics.ASTM, founded in 1898 as the

2 American Section of the International Association for Testing and Materials, predates other standards organizations such as BSI (1901), DIN (1917), ANSI (1918) and AFNOR (1926). 1.1.1 Standards The standards produced by ASTM International fall into SIX CATEGORIES: the Standard Specification, that defines the requirements to be satisfied by subject of the standard. the Standard Test Method, that defines the way a test is performed and the precision of the result. The result of the test may be used to assess compliance with a Standard Specification. the Standard Practice, that defines a sequence of operations that, unlike a Standard Test Method, does not produce a result. the Standard Guide, that provides an organized collection of information or series of options that does not recommend a specific course of action. the Standard Classification, that provides an arrangement or division of materials, products, systems, or services into groups based on similar characteristics such as origin, composition, properties, or use. the Terminology Standard, that provides agreed definitions of terms used in the other standards. The quality of the standards is such that they are frequently used worldwide 1.2 International Organization for Standardization (ISO) ISO SYMBOL The International Organization for Standardization (ISO) contains national standard organizations from over 90 countries. The object of ISO is to promote the development of standards in the world with a view to facilitating international exchange of goods and services, and to developing co operation in the sphere of intellectual. By enabling products from different markets to be directly compared, they facilitate companies in entering new markets and assist in the development of global trade on a fair

3 basis. The standards also serve to safeguard consumers and the end-users of products and services, ensuring that certified products conform to the minimum standards set internationally. 1.2.1 Structure ISO is a voluntary organization whose members are recognized authorities on standards, each one representing one country. Members meet annually at a General Assembly to discuss ISO's strategic objectives. The organization is coordinated by a Central Secretariat based in Geneva. A Council with a rotating membership of 20 member bodies provides guidance and governance, including setting the Central Secretariat's annual budget. The Technical Management Board is responsible for over 250 technical committees, who develop the ISO standards 1.2.2 What Is Process Procedure For Getting ISO Certificate ???? Organizations willing to achieve ISO certification shall follow steps mentioned below: 1) Decide ISO certification to be obtained. 2) Review advantages of ISO certification. 3) Contact ISO certification consultants if requirements of ISO system is not known. 4) Review existing work practices being followed in the company and identify gaps against requirements mentioned in ISO standards 5) Prepare action plan describing work to be done to fulfill requirements of ISO standard 6) Give trainings to all employees of organization about ISO requirements. 7) Complete necessary documentation like manual, procedures preparations. 8) Follow defined ISO system in routine and overcome difficulties in following same. 9) Conduct internal audit 10) Contact ISO certification agencies and finalize 3 year contract with them. 11) After ensuring adequate preparations for audit, call certification agency for stage 1 audit. 12) Close non conformities given by certification agencies during stage 1 audit. 13) Call certification agency for stage 2 ( final ) certification audit. 14) Close non conformities given by certification agency during stage 2 certification audit. 15) Receive ISO certificate after 4-6 weeks of successful completion of stage 2 certification audit 16) Use ISO logo as per recommendation of certification agency.

4 1.2.3 What are the SIX (6) mandatory "documented procedures" Ask these questions before drafting the procedures: 1. What is the required output of the procedure? 2. What is the most sensible method of generating that output? ISO 9001:2008 requires “documented procedures” for the following six activities: i. Control of documents (4.2.3) ii. Control of records (4.2.4) iii. Internal audit (8.2.2) iv. Control of nonconforming product (8.3) v. Corrective action (8.5.2) vi. Preventive action (8.5.3) Control of documents Process owner determines documentation needed --> Process owner creates document --> Process owner applies for document approval from Management Representative/Top Management --> MR reviews document for adequacy --> MR approves document, registers and assigns document code and version number in the Approved Documents Register or MR declines the approval application and returns the document to the process owner for amendments to be made --> MR sends approved document to process owner --> Document owner distributes approved document at point/s of use --> Process owner disposes obsolete version of document --> Document users use document --> Document users send feedback on document to process owner --> Process owner amends document if necessary --> Process owner applies for re-approval for amended document. Control of records Process owner determines records to control --> Determine retention period --> Determine storage location and labeling requirements --> List the records' profiles in the Records Register --> Management Representative reviews and approves the Records Register --> Maintain records at specific location until retention period ends --> Get records disposition approval from Management Representative --> Dispose records --> Record the disposition method and date.

5 Internal Audit Management Representative plans and documents the annual Internal Audit Schedule --> MR determines the audit scope and criteria --> MR assigns the auditors --> MR establishes the Audit Plan - -> MR distributes the Audit Plan to the assigned auditor and auditee --> Auditor and auditee prepare for the audit --> Auditor commences the audit with the Opening Meeting --> Auditor reviews the documentation related to the process being audited --> Auditor verifies conformance and effectiveness --> Auditor collects audit evidence --> Auditor gets auditee's agreeement --> Auditor prepares the Audit Report --> Auditor conducts the Closing Meeting and presents the Audit Report --> Auditor transfers all audit records to the Management Representative --> Management Representative commences any necessary follow-up action based on the Internal Audit Report. Control of nonconforming product Process owner detects nonconforming product --> Determine and implement appropriate remedial actions --> Verify nonconforming product if it was corrected --> Record all decisions and actions taken - -> Reports the nonconformity to the Management Representative. Corrective action Process owner/Auditor detects nonconformity (includes product nonconformity) and reports it to the Management Representative --> Management Representative reviews and verifies nonconformity --> Management Representative issues a Corrective Action Request to the process owner --> Process owner implements and records the corrections --> Process owner performs Root Cause Analysis on the nonconformity --> Process owner determines necessary corrective action --> Process owner implements corrective action --> Process owner records the corrective action that has been implemented --> Management Representative evaluates if corrective action was effective or otherwise - -> Management Representative issues a fresh Corrective Active Request if actions taken was found to be ineffective. Preventive action Process owner identifies potential nonconformity --> Process owner quantifies the risk in terms of its likelihood of occurrence and severity of consequence --> Process owner reports the potential nonconformity to the Management Representative if the risk of the potential nonconformity is significant --> Management Representative verifies the report and issues a Corrective Action Request to the process owner --> Process owner performs a Root Cause Analysis on the potential nonconformity --> Process owner determines necessary preventive actions to be taken --> Process owner implements

6 and records all actions taken including the results --> Management Representative evaluates if the actions taken was effective or otherwise--> Management Representative issues a fresh Preventive Active Request if actions taken was found to be ineffective. 1.3 American National Standard Institute (ANSI) ANSI SYMBOL The American National Standards Institute (ANSI) has served in its capacity as administrator and coordinator of the United States private sector voluntary standardization system for more than 90 years. Founded in 1918 by five engineering societies and three government agencies, the Institute remains a private, nonprofit membership organization supported by a diverse constituency of private and public sector organizations. Throughout its history, ANSI has maintained as its primary goal the enhancement of global competitiveness of U.S. business and the American quality of life by promoting and facilitating voluntary consensus standards and conformity assessment systems and promoting their integrity. The Institute represents the interests of its nearly 1,000 company, organization, government agency, institutional and international members through its office in New York City, and its headquarters in Washington, D.C. 1.3.1 Mission To enhance both the global competitiveness of U.S. business and the U.S. quality of life by promoting and facilitating voluntary consensus standards and conformity assessment systems, and safeguarding their integrity. 1.3.2 International Standardization ANSI promotes the use of U.S. standards internationally, advocates U.S. policy and technical positions in international and regional standards organizations, and encourages the adoption of international standards as national standards where they meet the needs of the user community. The Institute is the sole U.S. representative and dues-paying member of the two major non-treaty international standards organizations, the International Organization for Standardization (ISO), and, via the U.S. National Committee (USNC), the International Electrotechnical Commission (IEC). As a founding member of the ISO, ANSI plays a strong leadership role in its governing body while U.S. participation, via the USNC, is equally strong in the IEC.

7 Through ANSI, the U.S. has immediate access to the ISO and IEC standards development processes. ANSI participates in almost the entire technical program of both the ISO and the IEC, and administers many key committees and subgroups. Part of its responsibilities as the U.S. member body to the ISO include accrediting U.S. Technical Advisory Groups (U.S. TAGs), whose primary purpose is to develop and transmit, via ANSI, U.S. positions on activities and ballots of the international Technical Committee. U.S. positions for the IEC are endorsed and closely monitored by the USNC Technical Management Committee (TMC). In many instances, U.S. standards are taken forward to ISO and IEC, through ANSI or the USNC, where they are adopted in whole or in part as international standards. For this reason, ANSI plays an important part in creating international standards that support the worldwide sale of products, which prevent regions from using local standards to favor local industries. Since volunteers from industry and government, not ANSI staff, carry out the work of the international technical committees, the success of these efforts often is dependent upon the willingness of U.S. industry and government to commit the resources required to ensure strong U.S. technical participation in the international standards process. 1.3.3 Process Though ANSI itself does not develop standards, the Institute oversees the development and use of standards by accrediting the procedures of standards developing organizations. ANSI accreditation signifies that the procedures used by standards developing organizations meet the Institute's requirements for openness, balance, consensus, and due process. ANSI also designates specific standards as American National Standards, or ANS, when the Institute determines that the standards were developed in an environment that is equitable, accessible and responsive to the requirements of various stakeholders. Voluntary consensus standards quicken the market acceptance of products while making clear how to improve the safety of those products for the protection of consumers. There are approximately 9,500 American National Standards that carry the ANSI designation. The American National Standards process involves: consensus by a group that is open to representatives from all interested parties broad-based public review and comment on draft standards consideration of and response to comments incorporation of submitted changes that meet the same consensus requirements into a draft standard

8 availability of an appeal by any participant alleging that these principles were not respected during the standards-development process. 1.3.4 Standards panels The Institute administers nine standards panels: ANSI Homeland Defense and Security Standardization Collaborative (HDSSC) ANSI Nanotechnology Standards Panel (ANSI-NSP) ID Theft Prevention and ID Management Standards Panel (IDSP) ANSI Energy Efficiency Standardization Coordination Collaborative (EESCC) Nuclear Energy Standards Coordination Collaborative (NESCC) Electric Vehicles Standards Panel (EVSP) ANSI-NAM Network on Chemical Regulation ANSI Biofuels Standards Coordination Panel Healthcare Information Technology Standards Panel (HITSP) Each of the panels works to identify, coordinate, and harmonize voluntary standards relevant to these areas. In 2009, ANSI and the National Institute for Standards and Technology (NIST) formed the Nuclear Energy Standards Coordination Collaborative (NESCC). NESCC is a joint initiative to identify and respond to the current need for standards in the nuclear industry. 1.4 German Institute for Standardization (DIN) DIN SYMBOL Deutsches Institut für Normung e.V. (DIN; in English, the German Institute for Standardization) is the German national organization for standardization and is the German ISO member body. DIN is a Registered German Association (e.V.) headquartered in Berlin. There are currently around thirty thousand DIN Standards, covering nearly every field of technology.Founded in 1917 as the Normenausschuß der deutschen Industrie (NADI, "Standardisation Committee of German Industry"), the NADI was renamed Deutscher Normenausschuß (DNA, "German Standardisation Committee") in

9 1926 to reflect that the organization now dealt with standardization issues in many fields; viz., not just for industrial products. In 1975 it was renamed again to Deutsches Institut für Normung, or 'DIN' and is recognized by the German government as the official national-standards body, representing German interests at the international and European levels. The remit of DIN German Institute for Standardization is to encourage, organize, steer and moderate standardization and specification activities in systematic and transparent procedures for the benefit of society as a whole, while safeguarding the public interest. The results of DIN's work serve to advance innovation, safety and communication among industry, research organizations, the public sector and society as a whole, and to support quality assurance, rationalization, occupational health and safety, and environmental and consumer protection. DIN publishes its work results and promotes the implementation of these results. Some 30,000 experts contribute their skills and experience to the standardization process which is managed and coordinated by the DIN staff of around 400. By agreement with the German Federal Government, DIN is the acknowledged national standards body that represents German interests in European and international standards organizations. Ninety percent of the standards work now carried out by DIN is international in nature. A registered non-profit association, DIN has been based in Berlin since 1917. 1.4.1 DIN standard designation The designation of a DIN standard shows its origin (# denotes a number): DIN # is used for German standards with primarily domestic significance or designed as a first step toward international status. E DIN # is a draft standard and DIN V # is a preliminary standard. DIN EN # is used for the German edition of European standards. DIN ISO # is used for the German edition of ISO standards. DIN EN ISO # is used if the standard has also been adopted as a European standard. 1.4.2 Examples of DIN standards Main article: List of DIN standards DIN 476: international paper sizes (now ISO 216 or DIN EN ISO 216) DIN 1451: typeface used by German railways and on traffic signs DIN 31635: transliteration of the Arabic language DIN 72552: electric terminal numbers in automobiles

10 1.5 British Standard (BSI) BSI SYMBOL The BSI are the national standards organization for the UK and an influential member of the ISO. The main objective of the BSI is to publish and proliferate standards and standardisation both domestically and internationally. “Set up standards of quality for goods and services, and prepare and promote the general adoption of British Standards and schedules in connection therewith and from time to time to revise, alter and amend such standards and schedules as experience and circumstances require”. (BSI Royal Charter, Faller and Graham) Formally, as per the 2002 Memorandum of Understanding between the BSI and the United Kingdom Government, British Standards are defined as: "British Standards" means formal consensus standards as set out in BS 0-1 paragraph 3.2 and based upon the principles of standardisation recognised inter alia in European standardisation policy. 1.5.1 How British Standards are made The BSI Group as a whole does not produce British Standards, as standards work within the BSI is decentralized. The governing Board of BSI establishes a Standards Board. The Standards Board does little apart from setting up Sector Boards (a Sector in BSI parlance being a field of standardization such as ICT, Quality, Agriculture, Manufacturing, or Fire). Each Sector Board in turn constitutes several Technical Committees. It is the Technical Committees that, formally, approve a British Standard, which is then presented to the Secretary of the supervisory Sector Board for endorsement of the fact that the Technical Committee has indeed completed a task for which it was constituted. 1.5.2 The standards The standards produced are titled British Standard XXXX[-P]:YYYY where XXXX is the number of the standard, P is the number of the part of the standard (where the standard is split into multiple parts) and

11 YYYY is the year in which the standard came into effect. BSI Group currently has over 27,000 active standards. Products are commonly specified as meeting a particular British Standard, and in general this can be done without any certification or independent testing. The standard simply provides a shorthand way of claiming that certain specifications are met, while encouraging manufacturers to adhere to a common method for such a specification. The Kitemark can be used to indicate certification by BSI, but only where a Kitemark scheme has been set up around a particular standard. It is mainly applicable to safety and quality management standards. There is a common misunderstanding that Kitemarks are necessary to prove compliance with any BS standard, but in general it is neither desirable nor possible that every standard be 'policed' in this way. Following the move on harmonisation of the standard in Europe, some British Standards are gradually superseded or replaced by the relevant European Standards (EN). 1.5.3 Status of standards Standards are continuously reviewed and developed and are periodically allocated one or more of the following status keywords: Confirmed - the standard has been reviewed and confirmed as being current. Current - the document is the current, most recently published one available. Draft for public comment/DPC - a national stage in the development of a standard, where wider consultation is sought within the UK. Obsolescent - indicating by amendment that the standard is not recommended for use for new equipment, but needs to be retained to provide for the servicing of equipment that is expected to have a long working life, or due to legislative issues. Partially replaced - the standard has been partially replaced by one or more other standards. Proposed for confirmation - the standard is being reviewed and it has been proposed that it is confirmed as the current standard. Proposed for obsolescence - the standard is being reviewed and it has been proposed that it is made obsolescent. Proposed for withdrawal - the standard is being reviewed and it has been proposed that it is withdrawn. Revised - the standard has been revised. Superseded - the standard has been replaced by one or more other standards. Under review - the standard is under review.

12 Withdrawn - the document is no longer current and has been withdrawn. Work in hand - there is work being undertaken on the standard and there may be a related draft for public comment available. 1.5.4 Examples of British Standards BS 0 A standard for standards specifies Development, Structure and Drafting of British Standards themselves. BS 1 Lists of Rolled Sections for Structural Purposes BS 2 Specification and Sections of Tramway Rails and Fishplates BS 3 Report on Influence of Gauge Length and Section of Test Bar on the Percentage of Elongation BS 4 Specification for Structural Steel Sections BS 5 Report on Locomotives for Indian Railways BS 6 Properties of Rolled Sections for Structural Purposes BS 7 Dimensions of Copper Conductors Insulated Annealed, for Electric Power and Light BS 8 Specification for Tubular Tramway Poles And etc………………… 1.6 European Standard (EN) EN SYMBOL European Standards (ENs) are documents that have been ratified by one of the three European Standardization Organizations (ESOs), CEN, CENELEC or ETSI; recognized as competent in the area of voluntary technical standardization as for the EU Regulation 1025/2012. Although they deal with different fields of activity, CEN, CENELEC, and ETSI cooperate in a number of areas of common interest, such as the machinery sector or information and communication technologies (ICTs). They also share common policies on issues where there is mutual agreement. An EN (European Standard) “carries with it the obligation to be implemented at national level by being given the status of a national standard and by withdrawal of any conflicting national standard". Therefore, a European Standard (EN) automatically becomes a national standard in

13 each of the 33 CEN-CENELEC member countries. Standards are voluntary which means that there is no automatic legal obligation to apply them. However, laws and regulations may refer to standards and even make compliance with them compulsory. 1.6.1 Sectors The standardization activities of CEN and CENELEC cover products, processes and services across a wide range of particular fields. Although their fields of competence are generally different, CEN and CENELEC cooperate in a number of areas of common interest, such as the machinery sector or information and communication technologies (ICTs). Furthermore, they share common policies on a number of issues.In recent years, CEN and CENELEC activities have strongly focused on new challenges, fields and areas in which standardization activities had not previously been developed. These new fields are mainly innovative technologies such as nanotechnologies, smart grids, eco design, etc. 1.6.2 How to get involved ? There exist three main routes for stakeholders and interested parties to participate in the development of European Standards: At national level: Through the CEN National Standardization Bodies/CENELEC National Committees Through the national trade associations representing different sectors of business and industry At European Level Through European trade associations and federations Through European interest groups At International Level: Through the International Organization for Standardization (ISO) Through the International Electrotechnical Commission (IEC) CEN collaborates with the 'International Organization for Standardization' - ISO (according to the terms of the Vienna Agreement), while CENELEC works closely with the 'International Electrotechnical Commission' - IEC (Dresden Agreement). At the same time, all of CEN and CENELEC’s national members are also members of either ISO or IEC. These relationships help

14 to ensure that the interests of European businesses and other stakeholders are also taken into account at international level. 1.7 Japanese Industrial Standard (JIS) JIS SYMBOL Japanese Industrial Standards (JIS) (日本工業規格 Nippon Kōgyō Kikaku ? ) specifies the standards used for industrial activities in Japan. The standardization process is coordinated by the Japanese Industrial Standards Committee and published through the Japanese Standards Association. 1.7.1 Divisions in JIS The Japanese industrial standards are organized in the divisions: A. Civil Engineering and Architecture General Test and Inspection Design and Plan Accommodation and Fixture etc….. B. Mechanical Engineering General Machine and Parts Common to Factory Automation Tools, Jig and Implements etc……. C. Electronic and Electrical Engineering General Measuring and Testing Machine and Appliance Material Electric Wire, Cable and Electric Line Apparatus Electric Machine and Appliance etc……

15 D. Automotive Engineering General Method of Test and Inspection Common Parts Motors and Engine Chassis, Car Bodies etc……. E. Railway Engineering Track General Electric Car Line and Substation Signaling and Safety Appliance Rolling Stock General etc…. F. Shipbuilding General Hull Parts Engine Parts etc…. G. Ferrous Materials and Metallurgy General Analysis Method Raw Materials Carbon Steel etc……. H. Nonferrous materials and metallurgy K .Chemical Engineering L .Textile Engineering M. Mining P. Pulp and Paper Q .Management System R. Ceramics S .Domestic Wares T .Medical Equipment and Safety Appliances W .Aircraft and Aviation X. Information Processing Z .Miscellaneous

16 1.8 Malaysian Standard (MS) MS Symbol As the national accreditation body, STANDARDS MALAYSIA gives official recognition in the form of accreditation to organisations with established competence to provide conformity assessment services for the certification of management systems (e.g. certification of quality management systems according to ISO 9001certification of environmental management systems according to ISO 14001), product certification, testing, calibration and inspection. 1.8.1 Standards Malaysia Operates THREE CATEGORIES of accreditation schemes : i. Laboratory Accreditation Scheme of Malaysia (SAMM), ii. Accreditation of Certification Bodies (ACB) iii. Malaysia Inspection Bodies Accreditation Scheme (MIBAS). The SAMM Scheme includes accreditation of both testing and calibration laboratories, while the ACB scheme offers accreditation to certification bodies operating Management System Certification and Product Certification (which include Halal products certification). MIBAS, the latest accreditation scheme launched on 20 November 2006, is a unified national inspection bodies accreditation scheme and is multi-disciplinary in its scope, and is a formal recognition of the competence of an inspection body and its inspectors. These schemes are operated in accordance with established international standards and guides. STANDARDS MALAYSIA assures the credibility of assessment certificates issued by its accredited conformity assessment organisations through established regional and global multilateral recognition agreements. These arrangements enable recognition of certificates issued, facilitate trade and enhance the competitiveness of Malaysian goods and services in the global market. STANDARDS MALAYSIA is a signatory to Pacific Accreditation Cooperation (PAC), International Accreditation Forum (IAF), Asia Pacific Laboratory Accreditation Cooperation (APLAC) and International Laboratory Accreditation Cooperation (ILAC).

17 1.8.2 SIRIM Berhad STANDARDS MALAYSIA has appointed SIRIM Berhad as the sole national standards development agency. SIRIM Berhad, a company wholly owned by the Malaysian Government, was established on 1 September 1996 as a successor company to the Standards and Industrial Research Institute of Malaysia (SIRIM) upon the enactment of the Standards of Malaysia Act in 1996. This appointment has been formalised in an agreement between the Government of Malaysia and SIRIM Berhad concluded on 4 June 1997. The appointment assigns SIRIM Berhad the task of managing the standards development structure and managing Malaysian representation in relevant regional and international technical committees. 1.8.3 Malaysian Standards Development Process STANDARDS MALAYSIA oversees the development of Malaysian Standards undertaken by SIRIM Berhad through a transparent and consensus based process that involves the participation of all stakeholders. Figure 1.1 Development Process

18 1.8.4 Malaysian Standards Development Structure Figure 1.2 Malaysian Standard Development Structure

19 CHAPTER 2 MECHANICAL PROPERTIES 2.0 Introduction What is mechanical properties ???? Characteristics that indicate the elastic or inelastic behavior of a material under pressure (force), such as bending, brittleness, elongation, hardness, and tensile strength. A property that involves a relationship between stress and strain or a reaction to an applied force. 2.1 Tensile Tensile testing, also known as tension testing, is a fundamental materials science test in which a sample is subjected to a controlled tension until failure. The results from the test are commonly used to select a material for an application, for quality control, and to predict how a material will react under other types of forces. Properties that are directly measured via a tensile test are ultimate tensile strength, maximum elongation and reduction in area. From these measurements the following properties can also be determined: Young's modulus, Poisson's ratio, yield strength, and strainhardening characteristics. Uniaxial tensile testing is the most commonly used for obtaining the mechanical characteristics of isotropic materials. For anisotropic materials, such as composite materials and textiles, biaxial tensile testing is required. 2.1.1 Tensile specimen Tensile specimens made from an aluminum alloy. The left two specimens have a round cross-section and threaded shoulders. The right two are flat specimen designed to be used with serrated grips. A tensile specimen is a standardized sample cross-section. It has two shoulders and a gauge (section) in between. The shoulders are large so they can be readily gripped, whereas the gauge section has a smaller cross-section so that the deformation and failure can occur in this area.

20 The shoulders of the test specimen can be manufactured in various ways to mate to various grips in the testing machine. Each system has advantages and disadvantages; for example, shoulders designed for serrated grips are easy and cheap to manufacture, but the alignment of the specimen is dependent on the skill of the technician. On the other hand, a pinned grip assures good alignment. Threaded shoulders and grips also assure good alignment, but the technician must know to thread each shoulder into the grip at least one diameter's length, otherwise the threads can strip before the specimen fractures. In large castings and forgings it is common to add extra material, which is designed to be removed from the casting so that test specimens can be made from it. These specimens may not be exact representation of the whole workpiece because the grain structure may be different throughout. In smaller workpieces or when critical parts of the casting must be tested, a workpiece may be sacrificed to make the test specimens. For workpieces that are machined from bar stock, the test specimen can be made from the same piece as the bar stock. Figure 2.1 Work Pieces Tensile

21 2.1.2 Equipment tension Figure 2.2 Universal testing machine The most common testing machine used in tensile testing is the universal testing machine. This type of machine has two crossheads; one is adjusted for the length of the specimen and the other is driven to apply tension to the test specimen. There are two types: hydraulic powered and electromagnetically powered machines The machine must have the proper capabilities for the test specimen being tested. There are four main parameters: force capacity, speed, and precision and accuracy. Force capacity refers to the fact that the machine must be able to generate enough force to fracture the specimen. The machine must be able to apply the force quickly or slowly enough to properly mimic the actual application. Finally, the machine must be able to accurately and precisely measure the gauge length and forces applied; for instance, a large machine that is designed to measure long elongations may not work with a brittle material that experiences short elongations prior to fracturing. Alignment of the test specimen in the testing machine is critical, because if the specimen is misaligned, either at an angle or offset to one side, the machine will exert a bending force on the specimen. This is especially bad for brittle materials, because it will dramatically skew the results. This situation can be minimized by using spherical seats or U-joints between the grips and the test machine. If the initial portion of the stress–strain curve is curved and not linear, it indicates the specimen is misaligned in the testing machine.

22 The strain measurements are most commonly measured with an extensometer, but strain gauges are also frequently used on small test specimen or when Poisson's ratio is being measured. Newer test machines have digital time, force, and elongation measurement systems consisting of electronic sensors connected to a data collection device (often a computer) and software to manipulate and output the data. However, analog machines continue to meet and exceed ASTM, NIST, and ASM metal tensile testing accuracy requirements, continuing to be used today. 2.1.3 Process The test process involves placing the test specimen in the testing machine and slowly extending it until it fractures. During this process, the elongation of the gauge section is recorded against the applied force. The data is manipulated so that it is not specific to the geometry of the test sample. The elongation measurement is used to calculate the engineering strain, ε, using the following equation: where ΔL is the change in gauge length, L0 is the initial gauge length, and L is the final length. The force measurement is used to calculate the engineering stress, σ, using the following equation: where F is the tensile force and A is the nominal cross-section of the specimen. The machine does these calculations as the force increases, so that the data points can be graphed into a stress–strain curve. 2.1.4 Standard Test Method for Tensile Properties of Plastics (ASTM D638 - 14 ) Significance and Use This test method is designed to produce tensile property data for the control and specification of plastic materials. These data are also useful for qualitative characterization and for research and development: Some material specifications that require the use of this test method, but with some procedural modifications that take precedence when adhering to the specification. Therefore, it is advisable to refer to that material specification before using this test method. Table 1 in Classification D4000 lists the ASTM materials standards that currently exist.

23 Tensile properties are known to vary with specimen preparation and with speed and environment of testing. Consequently, where precise comparative results are desired, these factors must be carefully controlled. It is realized that a material cannot be tested without also testing the method of preparation of that material. Hence, when comparative tests of materials per se are desired, exercise great care to ensure that all samples are prepared in exactly the same way, unless the test is to include the effects of sample preparation. Similarly, for referee purposes or comparisons within any given series of specimens, care shall be taken to secure the maximum degree of uniformity in details of preparation, treatment, and handling. Tensile properties provide useful data for plastics engineering design purposes. However, because of the high degree of sensitivity exhibited by many plastics to rate of straining and environmental conditions, data obtained by this test method cannot be considered valid for applications involving load-time scales or environments widely different from those of this test method. In cases of such dissimilarity, no reliable estimation of the limit of usefulness can be made for most plastics. This sensitivity to rate of straining and environment necessitates testing over a broad load-time scale (including impact and creep) and range of environmental conditions if tensile properties are to suffice for engineering design purposes. 2.1.5 Example data of tensile Two example of tensile data: Table 2.1 Polyethylene Tensile Data

24 Table 2.2 Reinforced Polypropylene Tensile Data 2.2 Compressive Compression tests provide information about the compressive properties of plastics when employed under conditions approximating those under which the tests are made. Compressive properties include modulus of elasticity, yield stress, deformation beyond yield point, and compressive strength (unless the material merely flattens but does not fracture). Materials possessing a low order of ductility may not exhibit a yield point. In the case of a material that fails in compression by a shattering fracture, the compressive strength has a very definite value. In the case of a material that does not fail in compression by a shattering fracture, the compressive strength is an arbitrary one depending upon the degree of distortion that is regarded as indicating complete failure of the material. Many plastic materials will continue to deform in compression until a flat disk is produced, the compressive stress (nominal) rising steadily in the process, without any well-defined fracture occurring. Compressive strength can have no real meaning in such cases.

25 2.2.1 Compressive Strength The compressive strength of a material is the force per unit area that it can withstand in compression. This is in contrast to the more commonly measured tensile strength. ASTM D695 is the standard test method in the USA. The figure below, from Quadrant Engineering Plastic Products, shows the test geometry. ASTM D695: Specimen of 1/2" x 1/2" x 1" is placed in the compression apparatus and a known load is applied. North American plastics manufacturers generally report compressive yield strength, the stress measured at the point of permanent yield, zero slope, on the stress-strain curve. Ultimate compressive strength is the stress required to rupture a specimen. Materials such as most plastics that do not rupture can have their results reported as the compressive strength at a specific deformation such as 1%, 5%, or 10% of the test sample's original height. The analogous test to measure compressive strength in the ISO system is ISO 604. The values reported in the ASTM D695 and ISO 604 tests seldom differ significantly and are often used interchangably in the early stages of the materials selection process. These tests also give the procedure to measure a material's compressive modulus (the ratio of stress to strain in compression). The table below lists average compressive strengths and compressive moduli for some filled and unfilled polymers.

26 2.2.2 Standard Test Method for Compressive Properties of Rigid Plastics (ASTMD 695) Compression tests provide a standard method of obtaining data for research and development, quality control, acceptance or rejection under specifications, and special purposes. The tests cannot be considered significant for engineering design in applications differing widely from the load-time scale of the standard test. Such applications require additional tests such as impact, creep, and fatigue. Before proceeding with this test method, reference should be made to the ASTM specification for the material being tested. Any test specimen preparation, conditioning, dimensions, and testing parameters covered in the materials specification shall take precedence over those mentioned in this test method. If there is no material specification, then the default conditions apply. Table 1 in Classification D 4000 lists the ASTM materials standards that currently exist. Scope This test method covers the determination of the mechanical properties of unreinforced and reinforced rigid plastics, including high-modulus composites, when loaded in compression at relatively low uniform rates of straining or loading. Test specimens of standard shape are employed. This procedure is applicable for a composite modulus up to and including 41,370 MPa (6,000,000 psi). The values stated in SI units are to be regarded as the standard. The values in parentheses are for information only. Note 1—For compressive properties of resin-matrix composites reinforced with oriented continuous, discontinuous, or cross-ply reinforcements, tests may be made in accordance with Test Method D3410/D3410M. This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. A specific precautionary statement is given in 13.1. This test method is technically equivalent to ISO 604.

27 2.2.3 Flow of compression When a specimen of material is loaded in such a way that it extends it is said to be in tension. On the other hand if the material compresses and shortens it is said to be in compression. On an atomic level, the molecules or atoms are forced apart when in tension whereas in compression they are forced together. Since atoms in solids always try to find an equilibrium position, and distance between other atoms, forces arise throughout the entire material which oppose both tension or compression. The phenomena prevailing on an atomic level are therefore similar. The "strain" is the relative change in length under applied stress; positive strain characterises an object under tension load which tends to lengthen it, and a compressive stress that shortens an object gives negative strain. Tension tends to pull small sideways deflections back into alignment, while compression tends to amplify such deflection into buckling. Compressive strength is measured on materials, components, and structures. By definition, the ultimate compressive strength of a material is that value of uniaxial compressive stress reached when the material fails completely. The compressive strength is usually obtained experimentally by means of a compressive test. The apparatus used for this experiment is the same as that used in a tensile test. However, rather than applying a uniaxial tensile load, a uniaxial compressive load is applied. As can be imagined, the specimen (usually cylindrical) is shortened as well as spread laterally. A Stress–strain curve is plotted by the instrument and would look similar to the following: compression Figure 2.3 True Stress-Strain curve for a typical specimen

28 The compressive strength of the material would correspond to the stress at the red point shown on the curve. In a compression test, there is a linear region where the material follows Hooke's Law. Hence for this region where this time E refers to the Young's Modulus for compression. In this region, the material deforms elastically and returns to its original length when the stress is removed. This linear region terminates at what is known as the yield point. Above this point the material behaves plastically and will not return to its original length once the load is removed 2.2.4 Formula use in compressive strength There is a difference between the engineering stress and the true stress. By its basic definition the uniaxial stress is given by: where, F = Load applied [N], A = Area [m 2 ] As stated, the area of the specimen varies on compression. In reality therefore the area is some function of the applied load i.e. A = f(F). Indeed, stress is defined as the force divided by the area at the start of the experiment. This is known as the engineering stress and is defined by, A0=Original specimen area [m 2 ] Correspondingly, the engineering strain would be defined by: where l = current specimen length [m] and l0 = original specimen length [m] The compressive strength would therefore correspond to the point on the engineering stress strain curve defined by

29 where F * = load applied just before crushing and l * = specimen length just before crushing. 2.2.5 Example data of compressive strength 2.3 Shear In engineering, shear strength is the strength of a material or component against the type of yield or structural failure where the material or component fails in shear. A shear load is a force that tends to produce a sliding failure on a material along a plane that is parallel to the direction of the force. In structural and mechanical engineering the shear strength of a component is important for designing the dimensions and materials to be used for the manufacture/construction of the component (e.g. beams, plates, or bolts) In a reinforced concrete beam, the main purpose of reinforcing bar (rebar) stirrups is to increase the shear strength.

30 For shear stress applies where is major principal stress is minor principal stress To calculate: Given total force at failure (F) and the force-resisting area (e.g. the cross-section of a bolt loaded in shear), Ultimate Shear Strength ( ) is: 2.3.1 How to Test Plastic Properties Shear Strength data is obtained by mounting a specimen in a punch type shear fixture and the punch (1 in. D ) is pushed down at a rate of 0.005 in. per min until the moving portion of the specimen clears the stationary portion. Shear strength is calculated as the force/area sheared.Shear strength is particularly important in film and sheet products where failures from this type load may often occur. For the design of molded and extruded products it would seldom be a factor. Plastic sheets or molded plastic discs measuring 0.005 to 0.500 in. thick are used in the test. ASTM D-732. 2.4 Impact The impact strength describes the ability of a material to absorb shock and impact energy without breaking. The impact strength is calculated as the ratio of impact absorption to test specimen cross-

31 section. Toughness is dependent upon temperature and the shape of the test specimen. Two different methods of determining impact strength may be used here. Unlike impact strength, notch impact strength is determined using a notched test specimen, which increases the sensitivity of the test method. In addition, a distinction is drawn between the two methods according to Charpy and Izod. These two methods differ in that according to Charpy, the test specimen is supported at both ends, while according to Izod the test specimen is only clamped on one side. 2.4.1 Izod Impact Strength Several methods are used to measure the impact resistance of plastics - Izod, Charpy, Gardner, tensile impact, and many others. These impact tests allow designers to compare the relative impact resistance under controlled laboratory conditions and, consequently, are often used for material selection or quality control. However, these tests generally don't translate into explicit design parameters. The Izod impact test is the most common test in North America. The figure below, from Quadrant Engineering Plastic Products, depicts the Izod impact strength test apparatus. ASTMD256: A pendulum swings on its track and strikes a notched, cantilevered plastic sample. The energy lost (required to break the sample) as the pedulum continues on its path is measured from the distance of its follow through. Sample thickness is usually 1/8 in. (3.2 mm) but may be up to 1/2 in. (12.3 mm). The test method generally utilized in North America is ASTM D256. The result of the Izod test is reported in energy lost per unit of specimen thickness (such as ft-lb/in or J/cm) at the notch ('t' in

32 graphic at right). Additionally, the results may be reported as energy lost per unit cross-sectional area at the notch (J/m² or ft-lb/in²). In Europe, ISO 180 methods are used and results reported based only on the cross-sectional area at the notch (J/m²). Polymeric materials that are sensitive to the stress concentrations at the notch ('notch-sensitive') will perform poorly in the notched izod test. Engineers use this knowledge to avoid using such polymers in designs with high stress concentrations such as sharp corners or cutouts. Unnotched specimens are also frequently tested via the Izod impact method to give a more complete understanding of impact resistance. Izod impact tests are commonly run at low temperatures - down to -40°F (-40°C) or occasionally lower - to help gauge the impact resistance of plastics used in cold environments. The impact resistance of a specific commercial grade of polymer is a function of the base resin plus the presence of any impact modifiers (such as elastomers) and reinforcing agents that may be added by the manufacturer/compounder. Environmental factors other than temperature also play a role in impact resistance. For example, nylons (polyamides) generally experience higher impact strength in the conditioned state in equilibrium with atmospheric moisture than in a dry-as-molded state becasue of the plasticizing effect of absorbed moisture. 2.4.2 Charpy Impact Strength The Charpy impact strength test, or Charpy v-notch test, is a high strain rate test used to determine the amount of energy a material can absorb when impacted by a large impulse. The Charpy impact test was first used by the French engineer George Charpy in 1905. Charpy impact strength testing is a simple test in which a notched or unnotched specimen is struck by a pendulum arm to determine the impact strength of that specimen. The impact energy absorbed in impacting a plastic specimen in a Charpy test is assumed to be equal to the difference between the potential energy of the pendulum and the energy remaining in the pendulum after impacting the plastic specimen. Corrections accounting for friction and air-resistance losses must also be made to determine the true impact resistance of the plastic. Impact strength is an important design parameter to consider in plastic structures because it quantifies how a plastic material will withstand sudden shocks or large impulses. Charpy impact tests are used to determine the toughness of a material, the ductile-brittle transition temperature (DBTT) and ductility of a plastic material. Plastics will absorb impulses impacts differently

33 then static load impacts, often high strength plastics are also quite brittle, or having low impact strength. By testing plastics with the Charpy test method the impact resistance of the plastic can be determined. Charpy impact testing can also be used to determine the sensitivity of notched plastics specimens. Impact resistance of plastic notched specimens measures how will a cracked plastic specimen will withstand an impact. Charpy testing results of notched specimens are measured in energy loss per unit cross-sectional area, for example J/m2 or ft-lb/in2. Toughness of a plastic describes how much energy the plastic material will absorb while plastic deformation is occurring, and can be determined with Charpy impact resistance testing. ISO 179 and ASTM D6110 serve as standard test methods for Charpy impact resistance testing of plastics. These standard Charpy test methods are used for quantifying the impact resistance of plastic materials cover testing of notched plastic specimens. Results of standardized Charpy impact strength tests should be used for comparison between materials for quality assurance purposes. Figure 2.4 Charphy Machine ISO13802 is the international standard for the verification of pendulum impact testing machines. TestResources 402 Series Charpy impact strength test machine meets the requirements set by ISO 13802. The 402 Series test machine is also designed to meet the Charpy impact strength testing requirements of ASTM D6110. Email or call our staff with questions regarding Charpy impact resistance testing equipment.

34 2.4.2.1 Charpy Impact Strength - ISO 179 Energy per unit area required to break a test specimen under flexural impact. Test specimen is held as a simply supported beam and is impacted by a swinging pendulum. The energy lost by the pendulum is equated with the energy absorbed by the test specimen. Edgewise Impact Flatwise Impact Figure 2.5 Position Impact Testing is performed on either notched or unnotched specimens. The impact blow is in either the edgewise or the flatwise direction for most materials. For long fiber reinforced specimens the impact is either normal or parallel to the orientation of the fibers.

35 2.4.2.2 Types of Notch 2.5 Flexural The flexural strength of a material is defined as its ability to resist deformation under load. For materials that deform significantly but do not break, the load at yield, typically measured at 5% deformation/strain of the outer surface, is reported as the flexural strength or flexural yield strength. The test beam is under compressive stress at the concave surface and tensile stress at the convex surface. The figure below, from Quadrant Engineering Plastic Products, shows the test geometry for ASTM D790. Figure 2.6 Flexural Impact ASTM D790: Specimen of 1/8" x 1/2" x 5" is placed on two supports and a load is applied at the center. The load at yield is the sample material's flexural strength.

36 The analogous test to measure flexural strength in the ISO system is ISO 178. The values reported in the ASTM D790 and ISO 178 tests seldom differ significantly. These tests also give the procedure to measure a material's flexural modulus (the ratio of stress to strain in flexural deformation). The table below lists average flexural strengths and flexural moduli values for some filled and unfilled polymers. These values are a measure of stiffness; flexible materials such as elastomers have lower values than fiber reinforced engineering polymers used as metal substitutes such as polyimides or acetals. Typical Flexural Strength and Flexural Modulus of Polymers Polymer Type Flexural Strength (MPa) Flexural Modulus (GPa) ABS 75 2.5 ABS + 30% Glass Fiber 120 7 Acetal Copolymer 85 2.5 Acetal Copolymer + 30% Glass Fiber 150 7.5 Acrylic 100 3 Nylon 6 85 2.3 Polyamide-Imide 175 5 Polycarbonate 90 2.3 Polyethylene, MDPE 40 0.7 Polyethylene Terephthalate (PET) 80 1 Polyimide 140 3 Polyimide + Glass Fiber 270 12 Polypropylene 40 1.5 Polystyrene 70 2.5

37 2.6 Hardness Hardness is a measure of how resistant solid matter is to various kinds of permanent shape change when a compressive force is applied. Some materials, such as metal, are harder than others. Macroscopic hardness is generally characterized by strong intermolecular bonds, but the behavior of solid materials under force is complex; therefore, there are different measurements of hardness: scratch hardness, indentation hardness, and rebound hardness. Hardness is dependent on ductility, elastic stiffness, plasticity, strain, strength, toughness, viscoelasticity, and viscosity. 2.6.1 Rockwell Hardness Testing of Plastics The hardness testing of plastics is most often measured by the Rockwell hardness test or Shore (durometer) hardness test. Both methods measure the resistance of the plastic toward indentation, thereby providing an empirical hardness value. These hardness values do not necessarily correlate to other properties or fundamental characteristics. Rockwell hardness is generally chosen for 'harder' plastics such as nylon, polycarbonate, polystyrene, and acetal where the resiliency or creep of the polymer is less likely to affect the results. The Ball Indentation Hardness test (ISO 2039-1; DIN 53456) is used in Europe much more often than in North America. The Barcol hardness test is sometimes chosen for thermoset polymers. The figure below, from Quadrant Engineering Plastic Products, shows the Rockwell hardness test geometry. ASTMD785: A specimen of at least 1/4 inches (6.4 mm) thickness is indented by a steel ball. A small load is applied, the apparatus is zeroed, and then a larger load is applied and removed. After a short time with the preload still applied, the remaining indentation is read from the scale.

38 The results obtained from this test are useful measures of relative resistance to indentation of various grades of plastics. However, the Rockwell hardness test does not serve well as a predictor of other properties such as strength or resistance to scratches, abrasion, or wear, and should not be used alone for product design specifications. Different Rockwell hardness scales utilize different size steel balls and different loads. The three most common scales used for plastics are Rockwell E, Rockwell M, and Rockwell R; results reported from the Rockwell L scale are much rarer. Many other Rockwell hardness scales are used for metals, with Rockwell A, Rockwell B, and Rockwell C being the three most common. As seen in the charts below, the correlation between the Rockwell scales used for plastics is weak; attempts at conversion between the scales are therefore discouraged. 2.6.2 Vickers Hardness Testing Microhardness testing of metals, ceramics, and composites is useful for a variety of applications for which 'macro' hardness measurements are unsuitable: testing very thin materials like foils, measuring individual microstructures within a larger matrix, or measuring the hardness gradients of a part along the cross section. Microhardness testing per ASTM E-384 gives an allowable range of loads for testing with a diamond indenter; the resulting indentation is measured and converted to a hardness value. The actual indenters used are Vickers (more common; a square base diamond pyramid with an apical angle of 136°) or Knoop (a narrow rhombus shaped indenter). The result for either Vickers or Knoop microhardness is reported in kg/cm 2 and is proportional to the load divided by the square of the diagonal of the indentation measured from the test. The figure below, courtesy of New Age Instruments, shows the Vickers indenter geometry. VickersIndentation The figure at the left is a schematic diagram the square base diamond pyramid Vickers hardness indenter and sample indentation.

39 The load on the Vickers microhardness indenter usually ranges from a few grams to several kilograms. In contrast, 'Macro' Vickers loads vary from 1 to 120 kg. The indentations should be as large as possible, within the confines of sample geometry, to minimize errors in measuring the indentation (hence the reported hardness). Vickers hardness is also sometimes called Diamond Pyramid Hardness (DPH) owing to the shape of the indenter. Test samples should have a smooth surface and be held perpendicular to the indenter. All things being equal, a lighter indenter load will require a smoother surface for a satisfactory test. Samples are usually mounted in plastic to fix them during preparation and testing. 2.6.3 Shore (Durometer) Hardness Testing of Plastics The hardness of plastics is most commonly measured by the Shore® (Durometer) test or Rockwell hardness test. Both methods measure the resistance of plastics toward indentation and provide an empirical hardness value that doesn't necessarily correlate well to other properties or fundamental characteristics. Shore Hardness, using either the Shore A or Shore D scale, is the preferred method for rubbers/elastomers and is also commonly used for 'softer' plastics such as polyolefins, fluoropolymers, and vinyls. The Shore A scale is used for 'softer' rubbers while the Shore D scale is used for 'harder' ones. Many other Shore hardness scales, such as Shore O and Shore H hardness, exist but are only rarely encountered by most people in the plastics industry. The Shore hardness is measured with an apparatus known as a Durometer and consequently is also known as 'Durometer hardness'. The hardness value is determined by the penetration of the Durometer indenter foot into the sample. Because of the resilience of rubbers and plastics, the indentation reading my change over time - so the indentation time is sometimes reported along with the hardness number. The ASTM test method designation is ASTM D2240 00 and is generally used in North America. Related methods include ISO 7619 and ISO 868; DIN 53505; and JIS K 6301, which was discontinued and superceeded by JIS K 6253. The results obtained from this test are a useful measure of relative resistance to indentation of various grades of polymers. However, the Shore Durometer hardness test does not serve well as a predictor of other properties such as strength or resistance to scratches, abrasion, or wear, and should not be used alone for product design specifications. Shore hardness is often used as a proxy for flexibility (flexural modulus) for the specification of elastomers. The correlation between Shore hardness and flexibility

40 holds for similar materials, especially within a series of grades from the same product line, but this is an empirical and not a fundamental relationship. As seen in the charts below, the correlation between the two Shore Durometer hardness scales is weak; attempts at conversion between the scales are therefore discouraged. The correlation is higher for materials with similar resiliency properties, but is still too low for reliable conversions. Likewise, conversion between Shore Hardness and Rockwell hardness is discouraged. The charts below are taken from data in MatWeb's database provided by polymer manufacturers for specific product grades

41 Figure 2.7 Data Shore By Types Of Plastics 2.6.3 Brinell Hardness The Brinell scale /characterizes the indentation hardness of materials through the scale of penetration of an indenter, loaded on a material test-piece. It is one of several definitions of hardness in materials science. Proposed by Swedish engineer Johan August Brinell in 1900, it was the first widely used and standardised hardness test in engineering and metallurgy. The large size of indentation and possible damage to test-piece limits its usefulness. The typical test uses a 10 millimetres (0.39 in) diameter steel ball as an indenter with a 3,000 kgf (29 kN; 6,600 lbf) force. For softer materials, a smaller force is used; for harder materials, a tungsten carbide ball is substituted for the steel ball. The indentation is measured and hardness calculated as: where: P = applied force (kgf) D = diameter of indenter (mm) d = diameter of indentation (mm)

42 Brinell hardness is sometimes quoted in megapascals, the Brinell hardness number is multiplied by the acceleration due to gravity, 9.81 m/s 2 , to convert it to megapascals. The BHN can be converted into the ultimate tensile strength (UTS), although the relationship is dependent on the material, and therefore determined empirically. The relationship is based on Meyer's index (n) from Meyer's law. If Meyer's index is less than 2.2 then the ratio of UTS to BHN is 0.36. If Meyer's index is greater than 2.2, then the ratio increases. BHN is designated by the most commonly used test standards (ASTM E10-12 and ISO 6506–1:2005) as HBW (H from hardness, B from brinell and W from the material of the indenter, tungsten (wolfram) carbide). In former standards HB or HBS were used to refer to measurements made with steel indenters. HBW is calculated in both standards using the SI units as where: F = applied force (N) D = diameter of indenter (mm) d = diameter of indentation (mm) Figure 2.8 Brinell Hardness Test

43 CHAPTER 3 PHYSICAL PROPERTIES 3.0 Introduction A physical property is any property that is measurable whose value describes a state of a physical system. The changes in the physical properties of a system can be used to describe its transformations or evolutions between its momentary states. Physical properties are often referred to as observables. 3.1 Density The density, or more precisely, the volumetric mass density, of a substance is its mass per unit volume. The symbol most often used for density is ρ . Mathematically, density is defined as mass divided by volume: where ρ is the density, m is the mass, and V is the volume. In some cases (for instance, in the United States oil and gas industry), density is loosely defined as its weight per unit volume, although this is scientifically inaccurate – this quantity is more specifically called specific weight. For a pure substance the density has the same numerical value as its mass concentration. Different materials usually have different densities, and density may be relevant to buoyancy, purity and packaging. Osmium and iridium are the densest known elements at standard conditions for temperature and pressure but certain chemical compounds may be denser. To simplify comparisons of density across different systems of units, it is sometimes replaced by the dimensionless quantity "relative density" or "specific gravity", i.e. the ratio of the density of the material to that of a standard material, usually water. Thus a relative density less than one means that the substance floats in water.