Polyesters reprocessing

The analysis of literature data shows that the use of bisphenyl derivatives as elements of structure of polymeric chain allows one to produce liquid crystal polyesters, reprocessible from the melt into the articles of high deformation-strength properties and high heat resistance. 

Why might one monomer nylon and one monomer polyester polymers be easier to reprocess to the original monomer than those condensation polymers which contain two or more monomers ... 

It is noteworthy that reprocessing of either PEST, PC, or their mixtures can be facilitated by adding 0.2-0.5 wt% of titanium and zirconium esters that re-polymerize, copolymerize and bond these polyesters to fibers, flakes or rubber crumbs. The method has been successfully used to blend 80% recycled PET with recycled PC. The agent is re-activated every time the mixture is reprocessed, thus the alloy s properties improve during recycling [Schut, 1996]. 

Aromatic polyesters (AP) are thermo-stable pol5miers they are thermoplastic products useful for reprocessing into the articles and materials by means of formation methods from solutions and melts. 

Uncrosslinked-linked thermoplastic reprocessible polyester ketone and method for its production, Germany Patent Apphcation 3416445 A. 

The origin of the discoloration which occurs during the thermal reprocessing of polyesters has been widely discussed, but agreement on the exact chromophore is unresolved. The molecular weight of the chromo-phore is reported to be about 300-1000 [20] and was though to be bound to the polymer chain. Ideas on the nature of this chromophore range from... 

Thermosets are formed by an irreversible cross-linking reaction to form a rigid three-dimensional matrix. They cannot be reprocessed by heat and pressure. Examples include formaldehyde with urea, melamine and phenol resins (UF, MF and PF respectively), epoxy resins and unsaturated polyesters. Differences between thermoplastic and thermoset polymers are given in Table 1.2. 

Most recycling in the United States may be termed mechanical recycling. A very limited quantity of material primarily polyester bottle resin is reprocessed through chemical means such as methanolysis. 

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