RANDOM COPOLYMER MOULDING

The composition comprises, per 100 pbw, from 60 to 90 pbw of a propylene homopolymer (A) having a melt flow index from 0.1 to 20 g/10 min and from 40 to 10 pbw of a propylene random copolymer (B) containing from 3 to 20 mol % of ethylene and/or an alpha-olefin having from 4 to 6 carbon atoms, the melt flow index of which ranges from 25 to 3000 g/10 min. It is used in the manufacture of expanded granules and moulded cellular articles. 

The polyether triols are the most important class of polyether polyols and they are used in flexible PU foam fabrication. The majority of polyether triols used in flexible foams are copolymers of PO-EO. Random copolymers are used in continuous slabstock flexible foams and block copolymers (PO-EO), with terminal poly[EO] block, are used in moulded foams (hot moulding and cold cure moulding processes). 

A second trial involved moulding a ZN random copolymer PP, an mPP random copolymer, and an mPP homopolymer into large household articles. Easier flow of the mPPs in the barrel at lower shear rates gave a 10% reduction in plastication time and a 50% reduction in injection pressure. Optical properties of both mPPs were also noticeably better, improviing the aesthetics of the finished part. 

Comments F = film quality, bm = blow moulding. RCo = random copolymers, BCo = block copolymers. ... 

It can be seen that moulded flexible PU foams using EO capped polyether polyols (block copolymers PO-EO with terminal poly[EO] block) represent only 22% of total worldwide consumption and that the majority of foams are flexible slabstock PU foams which use random copolyethers of PO-EO. It can therefore be concluded that the most important polyols for flexible PU foams production are in fact the random copolyethers PO-EO. 

Comonomer ratio certainly has a profound effect on mechanical properties of the biopolymers. This is illustrated in Table 6 for a range of injection-moulded random HB-HV copolymers. These samples contained a small amount of talc as a nucleating agent and were annealed at 60 C for 24 h before mechanical testing at room tempera-... 

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