Đang chuẩn bị liên kết để tải về tài liệu:
Handbook of Polymer Synthesis Second Edition Episode 1

Tham khảo tài liệu 'handbook of polymer synthesis second edition episode 1', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 1 Polyolefins Walter Kaminsky University of Hamburg Hamburg Germany I. INTRODUCTION The polyolefins production has increased rapidly in the 40 years to make polyolefins the major tonnage plastics material worldwide. In 2003 55 million tons of polyethene and 38 million t a polypropene were produced 1 . These products are used for packing material receptacles pipes domestic articles foils and fibers. Polyolefins consist of carbon and hydrogen atoms only and the monomers are easily available. Considering environmental aspects clean disposal can be achieved by burning or by pyrolysis for instance. Burning involves conversion to CO2 and H2O exclusively. By copolymerization of ethene and propene with higher n-olefins cyclic olefins or polar monomers product properties can be varied considerably thus extending the field of possible applications. For this reason terpolymers of the ethene propene n-olefin type are the polymers with the greatest potential. Ethene can be polymerized radically or by means of organometallic catalysts. In the case of polyisobutylene a cationic polymerization mechanism takes place. All other olefins propene 1-butene 4-methylpentene are polymerized with organometallic catalysts. The existence of several types of polyethene as well as blends of these polymers provides the designer with an unusual versatility in resin specifications. Thus polyethene technology has progressed from its dependence on one low-density polymer to numerous linear polymers copolymers and blends that will extend the use of polyethene to many previously unacceptable applications. Polypropene also shows versatility and unusual growth potential. The main advantage is improved susceptibility to degradation by outdoor exposure. The increase in the mass of polypropene used for the production of fibers and filaments is inive of the versatility of this polymer. Synthetic polyolefins were first synthetisized by decomposition of diazomethane 2 . With the exception of polyisobutylene .