1、Designation: E 2015 04 (Reapproved 2009)Standard Guide forPreparation of Plastics and Polymeric Specimens forMicrostructural Examination1This standard is issued under the fixed designation E 2015; the number immediately following the designation indicates the year oforiginal adoption or, in the case
2、 of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This guide covers recommended procedures and guide-lines for the preparation of plastic and
3、polymeric specimens formicrostructural examination by light and electron microscopy.1.2 This guide is applicable to most semi-rigid and rigidplastics, including engineering plastics. This guide is alsoapplicable to some non-rigid plastics.1.3 The procedures and guidelines presented in this guideare
4、those which generally produce satisfactory specimens. Thisguide does not describe the variations in techniques required tosolve individual problems.1.4 Many detailed descriptions of grinding and polishing ofplastics and polymers are available (1-7).21.5 This standard does not purport to address all
5、of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:3D 883 Terminology Rela
6、ting to PlasticsE3 Guide for Preparation of Metallographic SpecimensE7 Terminology Relating to Metallography3. Terminology3.1 Definitions:3.1.1 For definitions used in this guide of terms directlyrelated to metallography, refer to Terminology E7.3.1.2 For definitions used in this guide of terms dire
7、ctlyrelated to plastics and polymers, refer to Engineering MaterialsHandbook, Vol 2 (8) and Terminology D 883.3.1.3 plastic(s)a material that contains as an essentialingredient one or more organic polymeric substances of largemolecular weight; is solid in its finished state; and at somestage in its
8、manufacture or processing into finished articles, canbe shaped by flow.3.1.4 polymer(s)a substance consisting of molecules char-acterized by the repetition (neglecting ends, branch junctions,and other minor irregularities) of one or more types ofmonomeric units.4. Significance and Use4.1 One of the
9、fundamental objectives of microstructuralexamination of manufactured materials, especially plastics andpolymers, is to gain a more complete understanding of therelationships between the manufacturing processes, the micro-structure and texture of the material, and the products perfor-mance (that is,
10、physical, optical, or mechanical properties, orcombination thereof). Under nearly all conditions, the properselection and preparation of the specimen are of major impor-tance.4.2 Because of the wide range of available equipment;physical, chemical, and mechanical properties of materials; andthe perso
11、nal element, specimen preparation is an art basedupon scientific principles. However, like metallographic speci-men preparation, certain methods, practices, and procedurescan be used to routinely produce acceptable quality plastic andpolymeric specimens for microstructural examination. Accept-able q
12、uality means:4.2.1 The observed microstructure is free of thermal, me-chanical, and chemical alterations, artifacts, damage, or defectsresulting from the specimen preparation process.4.2.2 A surface finish appropriate for the microscopicaltechniques to be used.4.2.3 The microstructure is reproducibl
13、y displayed for agiven specimen.4.3 The mounting, sectioning, grinding, and polishing pro-cedures in this guide may introduce thermal, mechanical, andchemical stresses on the material being prepared for micro-structural examination. Thus, knowledge of the materialsphysical, mechanical, and chemical
14、properties is of importancein selecting the most appropriate technique(s) to reveal its true1This guide is under the jurisdiction ofASTM Committee E04 on Metallographyand is the direct responsibility of Subcommittee E04.01 on Specimen Preparation.Current edition approved May 1, 2009. Published Septe
15、mber 2009. Originallyapproved in 1999. Last previous edition approved in 2004 as E 2015 04.2The boldface numbers in parentheses refer to the list of references at the end ofthis standard.3For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at servicea
16、stm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.microstructure and to minimize the total number of stepsnee
17、ded to produce high quality polished specimens.4.4 The general guidelines presented below will need to bemodified for each type of plastic or polymer to be prepared.Table X1.1 presents general procedures for preparing plasticsand polymers. Tables X1.2-X1.5 present procedures for pre-paring four poly
18、mers with very different mechanical proper-ties.5. Selection of Specimens5.1 The selection of test specimens is extremely importantand dependent upon the purpose of the examination, thematerial, and the microscopical technique to be used. Theprinciples of specimen selection presented in Practice E3s
19、hould be used as a primary guide for the selection of a plasticor polymeric test specimen.5.2 The selection criteria must include the following con-siderations:5.2.1 The size or scale of homogeneity/heterogeneity of allstructures, textures, and other features within the materialbeing studied;5.2.2 T
20、he size or scale and distribution of the structures tobe studied;5.2.3 The microscopical technique(s) to be used; and5.2.4 The need for control/reference specimens.5.3 Once the specimen locations have been selected, theselocations should be well documented. Macrographs or micro-graphs, or both, of t
21、he specimen locations along with briefspecimen location descriptions accompanying the written re-sults are usually sufficient.6. Size of Specimens6.1 The grinding and polishing procedures presented in thisguide require the use of automated grinding and polishingequipment. Therefore, the specimen siz
22、e will be limited by theholders available for the equipment to be used.7. Cleaning of Specimens7.1 Most plastics and polymers are very soft and subject toabrasion from debris produced during sectioning, grinding, andpolishing. In addition, oils and other surface films inhibituniform coating and adhe
23、sion of the mounting resin to thespecimen surface. Therefore, it is essential that the specimenand all specimen preparation surfaces be kept as clean aspossible. Thorough cleaning after each grinding and polishingstep will minimize contamination from the carry-over ofcoarser abrasives and debris tha
24、t may cause damage during thenext preparation step.7.2 The least aggressive solution, which effectively cleansthe specimen surface, should be used. This requires knowledgeof the specimens reactivity in potential cleaning solutions. Formany plastic and polymeric materials, cleaning with an aque-ous s
25、olution of dish soap is very effective. However, someplastics and polymers are subject to physical and chemicalchanges when placed in contact with aqueous solutions.7.3 The use of ultrasonic baths to promote cleaning isusually an acceptable practice. However, materials such aspartially cured resins
26、may be damaged by excessive cavitationin ultrasonic cleaning.8. Preliminary Sectioning and Mounting of Specimens8.1 Contrary to traditional metallographic procedures, smallspecimens or parts, or both, with the plane of interest notparallel to a flat surface may require mounting prior tosectioning to
27、 facilitate sectioning of the specimen parallel tothe desired plane to be polished. Also, laminated, friable, orvery ductile materials may be mounted prior to section tominimize damage during sectioning.8.2 In general, specimens should be mounted for sectioning,grinding, and polishing. Mounted speci
28、mens are typicallyeasier to handle and less susceptible to damage. Specimens areusually mounted in castable resins but may also be mechani-cally mounted. For very soft, flexible materials, it is oftennecessary to use a combination of mechanical mounting andmounting in a castable resin. Compression m
29、ounting in ther-moplastic or thermosetting plastic is generally not recom-mended but may be suitable for high temperature engineeringplastics.8.3 Preliminary sectioning may be necessary prior tomounting. This is usually accomplished by cutting or sawing ofthe unmounted part (see Section 9). These cu
30、ts should be madesufficiently far from the area of interest to minimize damagedue to sectioning yet close enough to minimize the nextmaterial removal step.8.4 The pre-sectioned specimen must be thoroughly cleanedand dried to remove any debris and oils from the suface thatmight inhibit the wetting an
31、d adhesion of the mountingmedium to the specimen surface.8.5 In many cases, there may be some reactivity between themounting medium and the specimen. Coating the specimenwith a 20 to 60-nm thick metal film of gold or gold/palladiumprovides an excellent barrier between the mounting mediumand the spec
32、imen. This metal coating also acts as an interfacethat will improve the adhesion of the mounting medium to thespecimen. The sputter coaters and vapor deposition coatersused to prepare conductive coatings for electron microscopyspecimens work very well for this application. In some cases,electroless
33、plating can be used to produce metal coatings on theplastics and polymers.8.6 Room temperature-cured, castable resins are generallyused to encapsulate plastic and polymeric specimens.8.6.1 It is critical that the manufacturers recommendedmixing proportions be followed precisely and that mixing ofthe
34、 components be thorough so that uniform and reproducibleresults will be achieved.8.6.2 Molds for castable resins can be easily produced in thelaboratory and a wide variety of shapes and compositions areavailable from various manufacturers. The molds may bereusable or not; the choice is a matter of c
35、onvenience and cost.Handling of these resins requires care. They all can causedermatitis as well as other problems.8.6.3 Styrene, latex, or other plastic spheres or particles canbe mixed into the mounting resin to modify the mechanicalproperties of the cured resin to more closely match those of thes
36、pecimen.8.6.4 Many plastics and polymers tend to float in themounting resins. Floating can be inhibited by placing aphenolic or other ringform on adhesive tape or by placingE 2015 04 (2009)2double-sided adhesive tape on the interior bottom of the mold,then attaching the specimen to the adhesive insi
37、de the ringformor mold and covering it with the mounting resin. Floating canalso be inhibited by partially surrounding the specimen withthe mounting resin and allowing the resin to partially cure, thenrepeating this step one or more times until the specimen iscompletely encased in mounting resin.8.6
38、.5 Many plastic and polymeric materials may be dam-aged by the heat produced during curing of castable resins.This can be minimized or eliminated by using the smallestvolume of resin necessary to encapsulate the specimen and byplacing the mounted specimen in a refrigerator or ice bathwhile the resin
39、 cures.8.7 Vacuum impregnation is a recommended method forensuring high quality mounts.8.8 The contrast between the specimen and castable mount-ing resin is often quite poor, making it difficult to identifyedges or study edge structures. A thick (100 nm) metalcoating ( see section 8.5) will help imp
40、rove the contrast at thespecimen-resin interface. Another approach is to charge theresin with a colorant or fluorescent dye, such as fluorescein.9. Cutting or Sectioning of Specimens9.1 In general, sectioning should produce a flat, relativelydamage-free surface very near to the region of interest.9.
41、1.1 Cutting with a sharp blade, scalpel, knife, or scissors isone of the fastest and most common methods for sectioningplastic and polymer films, tubing, and thin flexible parts. Thistechnique will introduce a strain (typically dominated byductile deformation) in the region near the cut face. The wi
42、dthof the strain region can be minimized by properly securing thesample during cutting, using a sharp instrument, making the cutwith uniform speed and force, and making the cut at theappropriate temperature (often below room temperature). Thecut face from a (cryogenically)microtomed specimen is ofte
43、nready for microstructural examination with minimal finalpolishing or without additional preparation.9.1.2 Sawing either manually or by machine is generally aconvenient method for sectioning rigid plastics. Sawing pro-duces a rather rough surface with a region of non-uniformstrain that is generally
44、wider than that produced by cutting. Thedeformation is often easily removed by the subsequent grind-ing and polishing steps. The width of the deformation regioncan be minimized by choosing a sharp, fine, short-toothedblade; a feed rate equal to the material removal rate; acoolant/lubricant that is n
45、on-reactive with the specimen; and ablade speed that does not cause a significant temperature rise inthe specimen and by presenting a minimum cross-sectionalarea of the part to the saw blade.9.1.3 Cutting or sectioning may also be accomplished by theuse of an abrasive cut-off wheel. This technique g
46、enerallyproduces a cut surface with deformation that can be removedby fine grinding and polishing. Abrasive wheels with 80 to120-grit abrasive cut soft epoxies quickly but leave a roughfinish, often with a relatively thick layer of ductile deformation.Finer grit (240 and above) abrasive wheels cut s
47、oft epoxiesquite slowly, tend to be quickly clogged with plastic orpolymer, and tend to wander. The force or load should besufficient to ensure a cutting or feed rate that is equal to theremoval rate. The blade speed should provide high removalrate without causing a significant temperature rise in t
48、hespecimen. A non-reactive coolant/lubricant, which contains asurfactant, will allow for high blade speeds, faster cutting, andminimal damage. The effectiveness of abrasive cut-off wheelscan be greatly improved by rotating the specimen about an axisthat is parallel to the axis of rotation of the cut
49、-off wheel.9.2 For machine assisted cutting or sectioning, it is alwaysadvisable to orient the specimen so that the blade, cutting tool,or abrasive wheel moves from the weakest or least supported tostrongest or best supported portion of the specimen whilepresenting the smallest cross-sectional area to the cutting tool.9.3 Carefully inspect the cleaned, cut face of mountedporous specimens. If the cut face exhibits open pores, re-impregnate the surface with a small amount of the mountingresin.10. Grinding10.1 The principles of grinding and polishing presented inPractice E3 shoul
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