tailieunhanh - Plastic Product Material and Process Selection Handbook Part 3

Tham khảo tài liệu 'plastic product material and process selection handbook part 3', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 54 Plastic Product Material and Process Selection Handbook Polyolefin Thermoplastic Elastomer TPEs are blends of various amorphous rubbers such as ethylenepropylene and of polyolefin semicrystalline plastics such as pp. They are part of the family of TP olefins TPOs . TPOs are mechanical blends consisting of a hard plastic and softer rubber. They are considered different from blends that are dynamically thermoplastic vulcanized TPV a process in which the elastomer phase is cured during mixing of the 94 Ethylene-Propylene Elastomer EP elastomers are random amorphous polymers with outstanding resistance to ozone aging and weathering mainly because of the saturated structure in their hydrocarbon backbone. These TPs also possess good low temperature flexibility and heat resistance and have excellent electrical properties. Their resistance to hydrocarbons and solvents is poor. The low density of these elastomers plus their ability to accept very high levels of extender oils and fillers often gives them a cost advantage over other elastomers in many applications. Principal applications are in automotive products single-ply roofing thermoplastic olefins and viscosity index improvers for lubricating oils. EP elastomers are the third-largest synthetic rubber consumed worldwide after styrene-butadiene rubber and polybutadiene rubber. World consumption of EP elastomers in 1998 was about 800 thousand metric tons. Polypropylene PPs are in the polyolefin family of plastics representing a major plastic used worldwide providing different performances. They have low specific gravity and good resistance to chemicals and fatigue pp made with metallocene catalysts mPP has improved characteristics such as toughness stiffness heat resistance clarity barrier properties high melt flow and high melt 95 Their densities are slightly lower than PEs but are much stiffer more heat resistant and have the same chemical and electrical resistance. They are semi-translucent .