ASTM_D_5224_-_12.pdf

Designation:D522412Standard Practice forCompression Molding Test Specimens of ThermosettingMolding Compounds1This standard is issued under the fixed designation D5224;the number immediately following the designation indicates the year oforiginal adoption or,in the case 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.Scope*1.1 This practice covers the general principles to be fol-lowed when compression molding test specimens of thermo-setting molding compounds,such as phenolics,aminoplastics,melamine phenolics,epoxies,and unsaturated polyesters.1.2 Molding conditions are given for amino,phenolic,andallyl molding compounds.The exact molding conditions willvary from material to material,and,if not incorporated in thematerial specification,shall be agreed upon between thepurchaser and the supplier or determined by previous experi-ence with the particular type of material being used1.3 The values stated in SI units are to be regarded asstandard.The values in parentheses are given for informationonly.1.4 This standard does not purport to address all 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.NOTE1This standard and ISO 295 address the same subject matter,but differ in technical content.2.Referenced Documents2.1 ASTM Standards:2D638 Test Method for Tensile Properties of PlasticsD883 Terminology Relating to Plastics2.2 ISO Standard:ISO 295 PlasticsCompression Molding Test Specimensof Thermosetting Materials3ISO 3167 PlasticsMultipurposeTest Specimens33.Terminology3.1 DefinitionsFor definitions of terms pertaining to plas-tics used in this practice,see Terminology D883.3.2 Definitions of Terms Specific to This Standard:3.2.1 breathe step,nin plastics molding,the part of themolding cycle in which the mold halves are openedmomentarily,prior to curing,to release volatiles from themolded part.3.2.2 skin,nin plastics molding,the thin resin-rich layer(skin)on the surface of the molded part.3.2.3 skin effect,nin plastics testing,the positive ornegative effect on the results of some standard tests attributableto the skin.4.Summary of Practice4.1 Compression molded test specimens are produced byloading a mold cavity with some form of the molding material,applying a specified pressure to the mating surface for aspecified time and at a specified temperature,and then remov-ing the part from the cavity.5.Significance and Use5.1 The conditions at which compounds are molded areknown to influence the properties of the specimens.The degreeof cure,elimination of knit-lines between particles,density ofthe part,and degradation of the polymer are among thosefactors which will be affected by the molding conditions.Thusit is important to conform to a standard set of conditions inorder to have a valid comparison of properties betweendifferent compounds and different batches of the same com-pound.5.2 Molded specimens showing evidence of low-densityareas due to trapped gases shall be discarded.A breathe stepcan be incorporated to eliminate this situation.If used,it iscritical that the breathe step be as brief as possible to avoidprecuring of the compound before full pressure is appliedleading to poorly“knitted”areas and lower strength in themolded specimen.6.Apparatus6.1 Molds:1This practice is under the jurisdiction ofASTM Committee D20 on Plastics andis the direct responsibility of Subcommittee D20.09 on Specimen Preparation.Current edition approved April 1,2012.Published May 2012.Originallyapproved in 1992.Last previous edition approved in 2006 as D5224-00(2006).DOI:10.1520/D5224-12.2For 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 page onthe ASTM website.3ISO Standards Handbook 21,Vol 2,Plastics,2nd Ed.,1990,available fromAmerican National Standards Institute(ANSI),25 W.43rd St.,4th Floor,NewYork,NY 10036.*A Summary of Changes section appears at the end of this standardCopyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 6.1.1 The mold shall be made of steel,able to withstand themolding temperatures and pressures.The mold shall be de-signed such that the compressive mold force is transferred tothe molding material with no appreciable loss.The moldsshown in Figs.1 and 2 are recommended for maintaining themaximum force on the material.They are of the three-platedesign;consisting of a shell or floating plate,with upper andlower compression plates.Molds may be of single or multiplecavity design.NOTE2Semi-positive molds can be used,and for materials such asamino compounds,are preferred.6.1.2 The majority