1、Designation: E2015 04 (Reapproved 2014)Standard Guide forPreparation of Plastics and Polymeric Specimens forMicrostructural Examination1This standard is issued under the fixed designation E2015; the number immediately following the designation indicates the year oforiginal adoption or, in the case o
2、f 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 po
3、lymeric 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 th
4、ose 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 of
5、 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:3D883 Terminology Relatin
6、g 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 directl
7、yrelated to plastics and polymers, refer to Engineering MaterialsHandbook, Vol 2 (8) and Terminology D883.3.1.3 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 manu
8、facture 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 fund
9、amental 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, phys
10、ical, 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 personal
11、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 quali
12、ty means:4.2.1 The observed microstructure is free of thermal,mechanical, and chemical alterations, artifacts, damage, ordefects resulting from the specimen preparation process.4.2.2 A surface finish appropriate for the microscopicaltechniques to be used.4.2.3 The microstructure is reproducibly disp
13、layed 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 materials1This guide is under the jurisdiction ofA
14、STM Committee E04 on Metallographyand is the direct responsibility of Subcommittee E04.01 on Specimen Preparation.Current edition approved Oct. 1, 2014. Published December 2014. Originallyapproved in 1999. Last previous edition approved in 2009 as E2015 04(2009).DOI: 10.1520/E2015-04R14.2The boldfac
15、e 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 serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary p
16、age onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1physical, mechanical, and chemical properties is of importancein selecting the most appropriate technique(s) to reveal its truemicrostructure and to minimize the t
17、otal number of stepsneeded 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 f
18、or pre-paring four polymers 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 pr
19、esented in Practice E3should 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 materi
20、albeing studied;5.2.2 The 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 ormicro
21、graphs, or both, of the specimen locations along withbrief specimen location descriptions accompanying the writtenresults are usually sufficient.6. Size of Specimens6.1 The grinding and polishing procedures presented in thisguide require the use of automated grinding and polishingequipment. Therefor
22、e, the specimen size 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 inhibitunifo
23、rm coating and adhesion 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 abras
24、ives and debris that 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
25、 with an aque-ous solution 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 aspart
26、ially cured resins 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 pr
27、ior tosectioning to 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 polis
28、hing. Mounted specimens 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 r
29、esin. Compression mounting 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 S
30、ection 9). These cuts 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 inh
31、ibit the wetting and 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
32、 mediumand the specimen. 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
33、 cases,electroless 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 an
34、d that mixing ofthe 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 choi
35、ce is a matter of convenience and cost.Handling of these resins requires care. They all can causedermatitis as well as other problems.E2015 04 (2014)28.6.3 Styrene, latex, or other plastic spheres or particles canbe mixed into the mounting resin to modify the mechanicalproperties of the cured resin
36、to more closely match those of thespecimen.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 placingdouble-sided adhesive tape on the interior bottom of the mold,then attaching the specimen to
37、 the adhesive inside 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
38、mounting resin.8.6.5 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 b
39、athwhile the resin 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
40、8.5) will help improve 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 reg
41、ion of interest.9.1.1 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 th
42、e cut face. The widthof 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)microtome
43、d specimen is oftenready 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
44、that is generally 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/l
45、ubricant that is non-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
46、. This technique generallyproduces 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) abr
47、asive wheels cut soft 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 tem
48、perature rise in thespecimen. 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 r
49、otation of the cut-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 i
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