1、Designation: D788 12Standard Classification System forPoly(Methyl Methacrylate) (PMMA) Molding and ExtrusionCompounds1This standard is issued under the fixed designation D788; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the yea
2、r 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.This standard has been approved for use by agencies of the Department of Defense.1. Scope1.1 The purpose of this classificati
3、on system is to provide amethod of adequately identifying PMMA materials using asystem consistent with that of Classification System D4000.Itfurther provides a means for specifying these materials by theuse of a simple line callout designation.1.2 This classification system covers poly(methyl methac
4、ry-late) molding and extrusion compounds. These compounds arepolymers based on methyl methacrylate, and at least 70 % ofthe polymer shall be polymerized from methyl methacrylate.1.3 The properties in this classification system are thoserequired to identify the compositions covered. Other require-men
5、ts necessary to identify particular characteristics importantto specific applications shall be described by using the suffixesas given in Section 5.1.4 Acrylic molding and extrusion compounds are usedfrequently in applications where extreme clarity and the abilityto retain that clarity and color und
6、er severe weathering andother environmental exposures are of primary significance.While the test specimen properties of this document extend tothe evaluation of nonvirgin materials, the user must takeprecautions to ensure that parts made from these materials meetthe desired end-use requirements. Acc
7、ordingly, this specifica-tion allows for the use of those acrylic plastic materials that canbe recycled, reconstituted, and reground provided the follow-ing:1.4.1 The requirements as stated in this specification aremet,1.4.2 The material has not been modified in any way to alterits conformance to fo
8、od contact regulations or similarrequirements, and1.4.3 The requirements of the particular end-use applicationare met.1.5 This classification system and subsequent line callout(specification) are not intended for the selection of materials,but only as a means to call out plastic materials to be used
9、 forthe manufacture of parts. The selection of these materials is tobe made by personnel with expertise in the plastics field inwhich the environment, inherent properties of the materials,performance of the parts, part design, manufacturing process,and economics are considered.NOTE 1This classificat
10、ion system is similar to ISO 8257-1:1987 intitle only. The technical content is significantly different.1.6 The values stated in SI units are to be regarded asstandard.1.7 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of
11、 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:2D149 Test Method for Dielectric Breakdown Voltage andDielectric Strength of Solid Electrical Insulating
12、Materialsat Commercial Power FrequenciesD150 Test Methods for AC Loss Characteristics and Permit-tivity (Dielectric Constant) of Solid Electrical InsulationD257 Test Methods for DC Resistance or Conductance ofInsulating MaterialsD618 Practice for Conditioning Plastics for TestingD883 Terminology Rel
13、ating to PlasticsD1003 Test Method for Haze and Luminous Transmittanceof Transparent PlasticsD1238 Test Method for Melt Flow Rates of Thermoplasticsby Extrusion PlastometerD1600 Terminology forAbbreviated Terms Relating to Plas-tics1This classification system is under the jurisdiction ofASTM Committ
14、ee D20 onPlastics and is the direct responsibility of Subcommittee D20.15 on ThermoplasticMaterials.Current edition approved Aug. 1, 2012. Published September 2012. Originallyapproved in 1944. Last previous edition approved in 2012 as D788 - 11. DOI:10.1520/D0788-12.2For referenced ASTM standards, v
15、isit 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 page onthe ASTM website.*A Summary of Changes section appears at the end of this standardCopyright ASTM International,
16、 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1D3641 Practice for Injection Molding Test Specimens ofThermoplastic Molding and Extrusion MaterialsD3892 Practice for Packaging/Packing of PlasticsD4000 Classification System for Specifying Plastic Materi-alsE29 Pra
17、ctice for Using Significant Digits in Test Data toDetermine Conformance with Specifications2.2 ISO Standards and Recommendations:3ISO 179 PlasticsDetermination of Charpy ImpactPropertiesPart 1: Non-Instrumented Impact TestISO 294 PlasticsInjection Moulding of Test Specimens ofThermoplastic Materials
18、Part 1: General Principles, andMoulding of Multipurpose and Bar Test SpecimensISO 306 PlasticsThermoplastic MaterialsDeterminationof Vicat Softening TemperatureISO 489 PlasticsDetermination of the Refractive Index ofTransparent PlasticsISO 527 PlasticsDetermination of Tensile PropertiesISO 1133 Plas
19、ticsDetermination of the Melt Flow Rate ofThermoplasticsISO 3167 PlasticsPreparation and Use of MultipurposeTest SpecimensISO 8257-1 PlasticsPoly(Methyl Methacrylate) (PMMA)Moulding and Extrusion MaterialsPart 12.3 SAE Standards:4SAE J576 SEP86SAE Recommended Practice for PlasticMaterials for Use in
20、 Optical Parts such as Lenses andReflectors for Motor Vehicle Lighting DevicesSAE J1885 AUG87SAE Recommended Practice for Ac-celerated Exposure of Automotive Interior Trim Compo-nents Using a Controlled Irradiance Water Cooled XenonArc ApparatusSAE J1960 JUN89SAE Standard for Accelerated Expo-sure o
21、f Automotive Exterior Materials Using a ControlledIrradiance Water Cooled Xenon Arc Apparatus3. Terminology3.1 DefinitionsThe terminology used in this classificationsystem is in accordance with Terminologies D883 and D1600.4. Basis of Classification4.1 Poly(methyl methacrylate) molding and extrusion
22、 com-pounds are classified into groups in accordance with theircomposition. These groups are subdivided into classes andgrades as shown in Table 3. A complete classification mustinclude reference to melt-flow rate, as discussed in 4.2 and5.1.4.4.1.1 To facilitate the incorporation of future or speci
23、almaterials, the “other/unspecified” category (0) for group, class,and grade is given in Table 3.4.1.2 When the grade of the basic material is not shown, oris not important, the use of “0” grade classification shall beused in this classification system.4.2 The melt-flow rate can vary within a given
24、group, class,and grade and can overlap classes or grades. For this reason,the melt-flow rate shall be specified using Suffix V.4.2.1 Although the values listed in Suffix V are necessary toinclude the range of properties available in existing materials,users must not infer that every melt-flow rate e
25、xists for eachclass or grade.NOTE 2An example of this classification system is as follows:The designation PMMA0112 indicates:PMMA = poly(methyl methacrylate) as found in Terminology D1600,01 = unmodified (group),1 = minimum 77C Vicat, etc. (class) and2 = ultraviolet transmitting (grade).(See Note 4
26、for a more complete example.)NOTE 3Major industries using these materials now require interna-tionally accepted test methods for product specifications. For this reason,ISO test methods have been used in Table 3 and elsewhere in thisclassification system where appropriate. Similar ASTM standards hav
27、ebeen listed in Section 2. Many of these ASTM standards are now or soonwill be equivalent. In future editions, a note in the ASTM standard willindicate the degree of equivalency with a particular international standard.The corresponding ASTM test method is to be substituted as long as thespecimen si
28、ze and all other conditions of the test method noted in thisclassification system as applying to the ISO test method are also appliedto the ASTM standard.4.3 Grade 1 materials are used where special ultraviolettransmission, filtering, or stabilization characteristics are notrequired.4.4 Grade 2 mate
29、rials are used for those specialized appli-cations in which the greatest amount of transmission of UVlight is required. The transmission properties are given in Table1.4.5 Grade 3 materials (transparent UV stabilized or trans-parent UVabsorbing) are used when either special resistance toslight color
30、 change over long exposure times or high-intensityUV radiation is required, or when the material is required tofilter out ultraviolet light. These applications are varied and3Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org
31、.4Available from SAE International (SAE), 400 Commonwealth Dr., Warrendale,PA 15096-0001, http:/www.sae.org.TABLE 1 Transmission of Grade 2 Materials at VariousWavelengthsA,BWavelength, nm Transmission, min, %400 86340 85310 70290 50280 26270 12AMeasured with UV spectrophotometer using an integratin
32、g sphere and a samplethickness of 3.2 mm.BThese requirements are in addition to the luminous transmittance requirementsgiven in Table 3.TABLE 2 Electrical Properties of Unmodified PMMAPropertyTestMethodRequirementInsulation resistance, min, Mohm D257 1107Dielectric strength min, kV/mmAD149 13.8Diele
33、ctric constant at 1 MHz, max D150 4.5Dissipation factor at 1 MHz, max D150 0.05AkV/mm 25.4 = V/mil.D788 122require specific light transmission or color-stability propertiesto be specified by the user.5. Suffixes5.1 When additional requirements are needed, based on theapplication, that are not covere
34、d by the basic cell-tablerequirements, they shall be indicated through the use ofsuffixes. In general, suffixes consist of a suffix letter, whichgives the requirement needed, a first digit, which gives the testcondition, and a second digit, which gives the specific require-ment.5.1.1 Suffix E = Elec
35、trical requirements, as designated bythe following digits:First Digit0 = to be specified by the user.1 = specimen thickness, 3.2 mm, nominal.Second Digit0 = to be specified by the user.1 = volume resistivity, dielectric constant, and dissipation factormeet property limits as given in Table 2.TABLE 3
36、 PMMA Poly(Methyl Methacrylate) Materials Detail RequirementsNoteThe values listed were developed for natural colors. Colorants or other additives, or both, have the potential to alterthese properties.Group Description Class DescriptionAGrade DescriptionACharpyImpact,TestMethodISO 179BkJ/m2,minTensi
37、leStrength,TestMethodISO 527,CMPa, minLuminousTransmittance,Test MethodD1003,D%, minHaze,TestMethodD1003,D%, maxIndex ofRefraction,TestMethodISO 489DTensileModulus,TestMethodISO 527,CMPa, minVicatSofteningTemperature,Test MethodISO 306,EC, min01 UnmodifiedF1 Formerly 1 General purpose . 58 90 2.5 1.
38、48-1.50 2700 77Grade 5 2 UV transmittingG. 58 90 2.5 1.48-1.50 2700 77(D788 - 84) 3 UV stabilizedH. 58 90 2.5 1.48-1.50 2700 772 Formerly 1 General purpose . 62 90 2.5 1.48-1.50 2700 86Grade 6 2 UV transmittingG. 62 90 2.5 1.48-1.50 2700 86(D788 - 84) 3 UV stabilizedH. 62 90 2.5 1.48-1.50 2700 863 F
39、ormerly 1 General purpose . 65 90 2.5 1.48-1.50 2700 95Grade 8 2 UV transmittingG. 65 90 2.5 1.48-1.50 2700 95(D788 - 84) 3 UV stabilizedH. 65 90 2.5 1.48-1.50 2700 954 Higher VicatSofteningPoint thanFormerGrade 81 General purpose . 65 90 2.5 1.48-1.50 2700 1042 UV transmittingG. 65 90 2.5 1.48-1.50
40、 2700 1043 UV stabilizedH. 65 90 2.5 1.48-1.50 2700 10402 Impact 1 1 1.2 51 88 4.0 1.48-1.50 2600 95modifiedI0 Other/unspecified. . . . . . .2 1 2.0 38 88 4.0 1.48-1.50 2500 903 1 4.3 31 88 4.0 1.48-1.50 1700 854 1 3.0 31 88 4.0 1.48-1.50 1700 8503 Heat-ResistancemodifiedJ1 1 General purpose . 65 90
41、 2.5 1.48-1.50 2700 1132 UV transmittingG. 65 90 2.5 1.48-1.50 2700 1133 UV stabilizedH. 65 90 2.5 1.48-1.50 2700 1134 Impact modified also tbd 56 88 4.0 1.48-1.50 tbd 1132 1 General purpose . 65 90 2.5 1.48-1.50 2700 1222 UV transmittingG. 65 90 2.5 1.48-1.50 2700 1223 UV stabilizedH. 65 90 2.5 1.4
42、8-1.50 2700 12200 Other 0 0 Other/unspecified . . . . . . .ANo descriptions are listed unless needed to describe a special grade or class. All other categories are listed by requirements.BPreferred test specimens are 4 by 10 by 80 mm with a notch radius of 0.25 mm with 8-mm depth below notch (Type 1
43、) and are tested by Method A. When necessary,to fit existing equipment, these specimens must be cut to 63.5-mm length. Annealing is neither required nor prohibited.CTest specimens are tensile bars with dimensions corresponding to the ISO 3167 multipurpose test specimen, tested at a crosshead speed o
44、f 1 mm/min to obtain tensilemodulus. As an option, the crosshead speed is increased to 5mm/min to obtain the tensile strength value when the test specimen has reached a minimum of 0.3 %elongation. Annealing is neither required nor prohibited.DTest specimens are 3.2-mm thick of colorless material.ETe
45、st specimens are 4-mm thick, tested at a rate of 50C/h and a load of 50 N. They must be placed in a desiccator immediately after molding to prevent water pickupand kept dry until ready for test or redried for 16 h at 80 3C and then cooled in a desiccator until ready for test.FUnmodified group materi
46、als are polymerized from 70 to 100 % methacrylate monomer and 0 to 30 % acrylic comonomers.GSee 4.4 for description.HSee 4.5 for description.IImpact-modified materials contain 50 to 95 % unmodified polymer and 5 to 50 % of impact modifier(s), maintaining the requirement that the overall composition
47、of thesematerials is polymers made from monomers, at least 70 % of which are methyl methacrylate.JHeat-resistance modified materials are polymerized from 70 to 95 % methyl methacrylate monomer and 5 to 30 % comonomers.D788 1235.1.2 Suffix H = Heat-stability requirements, as designatedby the followin
48、g digits:First Digit0 = to be specified by the user.1 = 1000 h at 70 2C.2 = 1000 h at 80 2C.3 = 1000 h at 90 2C.Second Digit0 = to be specified by the user.1 = change in tensile strength and impact strength not to exceedlimits as given in Table 4A after aging in an air-circulating ovenat the conditi
49、ons indicated by the first digit and subsequentconditioning according to Section 12.112.2.2 = change in tensile strength, tensile elongation, and impactstrength not to exceed limits as given in Table 4B after agingin an air-circulating oven at the conditions indicated by the firstdigit and subsequent conditioning according to Section12.112.2.5.1.3 Suffix T = Light Transmission and Haze,Modification, as designated by the following digits:First Digit0 = unspecified1 = light diffusing polymer modified, minimum transmission 80 %2 = light diffusing
