Tham khảo tài liệu 'plastics product design part 2', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 20 Plastics Engineered Product Design of molding BMCs is compression. They can also be injection molded in much the same way as other RTS compounds using ram ram-screw and for certain BMC mixes conventional reciprocating screw. Commodity Et Engineering Plastics About 90wt of plastics can be classified as commodity plastics CPs the others being engineering plastics EPs . The EPs such as polycarbonate PC representing at least 50wt of all EPs nylon acetal etc. are characterized by improved performance in higher mechanical properties better heat resistance and so forth Table . Table Thermoplastic engineering behaviors Crystalline Amorphous Acetal Polycarbonate Best property balance Good impact resistance Stiffest unreinforced thermoplastic Transparent Low friction Good electrical properties Nylon Modified PPO High melting point Hydrolytic stability High elongation Good impact resistance Toughest thermoplastic Absorbs moisture Polyester glass-reinforced High stiffness Lowest creep Excellent electrical properties Good electrical properties The EPs demand a higher price. About a half century ago the price per pound was at 20 t at the turn of the century it went to and now higher. When CPs with certain reinforcements and or alloys with other plastics are prepared they become EPs. Many TSs and RPs are EPs. Elastomers Rubbers In the past rubber meant a natural thermoset elastomeric TSE material obtained from a rubber ưee hevea braziliensis. The term elastomer developed with the advent of rubber-like synthetic materials. Elastomers identify natural or synthetic TS elastomers TSEs and thermoplastic elastomers TPEs . At room temperature all elastomers basically sưetch under low sưess to at least twice in length and snaps back to approximately the original length on release of the sưess pull within a specified time period. 1 Overview 21 The term elastomer is often used interchangeably with the term plastic or rubber however certain industries use only one or the .
