Search results
Results from the WOW.Com Content Network
The polymer is also a starting material for thermoplastic polyurethane, thermoplastic polyesters, polyetheramide and cast polyurethane elastomers, used for instance in the wheels of roller skates and skateboards.
Therefore, this polymer relies solely on physical anchor points. When heated up to Tg, the material abruptly changes from a rigid state to a tapered state (softens). To achieve the effect, the shape must be changed rapidly to avoid rearrangement of the segments of the polymer chains and immediately cool the material also very rapidly below Tg.
The Flory–Fox equation relates the number-average molecular weight, M n, to the glass transition temperature, T g, as shown below: =, where T g,∞ is the maximum glass transition temperature that can be achieved at a theoretical infinite molecular weight and K is an empirical parameter that is related to the free volume present in the polymer sample.
It is a synthetic acrylate polymer derived from butyl acrylate monomer. The polymers are colorless. This homopolymer is far less important than copolymers derived from methyl acrylate and other monomers. It has a low glass-transition temperature of about -43 °C (20 °C). [clarification needed]
A topology change is possible by transesterification reactions which do not affect the number of links or the (average) functionality of the polymer, meaning that neither the decomposition of polymer linkages nor the decrease of integrity of polymers happens when transesterification reactions take place.
Polycyclohexylenedimethylene terephthalate (PCT) is a thermoplastic polyester formed from the polycondensation of terephthalic acid and cyclohexanedimethanol. [1] Its chemical structure is similar to that of polyethylene terephthalate (PET), with which it shares properties like dimensional stability and chemical resistance.
Although thermal degradation is defined as an oxygen free process it is difficult in practise to completely exclude oxygen. Where this is the case thermal oxidation is to be expected, leading to the formation of free radicals by way of hydroperoxides. These may then participate in thermal degradation reactions, accelerating the rate of breakdown.
The PPE blends are characterized by hot water resistance with low water absorption, high impact strength, halogen-free fire protection and low density. This plastic is processed by injection molding or extrusion; depending on the type, the processing temperature is 260–300 °C. The surface can be printed, hot-stamped, painted or metallized.