Semi-aromatic polymers

An increase in heat deflection temperature of some thermoplastic polymers can be achieved by the addition of polyfunctional aromatic cyanates (BPA/DC in particular) and trimerization catalysts. A rigid network is formed as a resul t of the cyanate trimerization. The polymer material consists of a linear polymer and a crosslinked network and belongs to the class of semi-IPNs (semi-interpenetrating Polymer Networks) the corresponding classification is given in [34-37]. 

Gilmer TC et al. (1996) Synthesis, characterization, and mechanical properties of PMMA/poly(aromatic/aliphatic siloxane) semi-interpenetrating polymer networks. J Poly Sci Part A Poly Chem 34(6) 1025—1037... 

For flexible aliphatic polymers, e.g. poly(oxy methylene), sm has a value of 0.175 K MPa-1 for semi-rigid aromatic polymers (such as PEEK) the value of sm is much larger, viz. 0.5 K MPa-1. 

Since the 1970s the interest in semi-rigid aromatic polymers (aramids and arylates a.o.) is increasing. Dissolving of these polymers maybe very difficult and requires rather unusual solvent. A survey of suitable solvents is given in Table 7.13. 

TABLE 7.13 Solvents for (Semi-) rigid-rod aromatic polymers (after Lenz (1985))... 

Cakir S, Nieuwenhuizen M, Janssen PG, Rulkens R, Koning CE. Incorporation of a semi-aromatic nylon salt into polyamide 6 by solid-state or melt polymerization. Polymer 2012 53(23) 5242-50. 

It has been known since the early days that behavior of the aromatic polyamides (aramids) depends critically on the type of isomeric substitutions -para-substimtimis result in crystalline, while mefa-substitutions in amoiphous polymers (Kwolek et al. 1962). Similarly, the two aramids poly(m-xylene adipamide) and poly (hexamethylene isophthalamide), MXD6 and PA-61, respectively, show different miscibility, e.g., with aliphatic polyamides. Clearly, blind application of the segmental interaction strategy to aromatic or semi-aromatic polyamides leads to conflicts. However, the problem can be resolved considering p- and m-substituted phenyl as two different statistical segments (Ellis 1995). This idea is indeed evident in the segmental contributions listed in Table 2.14. 

Rosu, D., Rosu, L., Varganici, C.-D. The thermal stability of some semi-interpenetrated polymer networks based on epoxy resin and aromatic polyurethane. J. Anal. Appl. Pyrol. 100, 103-110 (2013)... 

Another aromatic polymer within this family of thermoplastic polymers was the semi-crystalUne polymer polyphenylene sulphide (PPS), which offered better impact toughness and had a greater resistance to vacuum and thermal q cUng than its thermoplastic and thermosetting counterparts, Cogswell (1992). 

A decision to develop PEEK so as to extend ICI s "VICTREX" range of aromatic polymers with a crystalline material was taken in 1979 and work started to scale up the laboratory process using semi technical equipment previously assembled for the unsuccessful development of the ketone-sulphone co polymer The process so developed was established in... 

Poly(ethylene terephthalate) (abbreviated PET or PETE) is a semi-aromatic thermoplastic polyester obtained by condensation reaction of difunctional reactants and well-known for more than 60 years. PET is commonly produced by esterification reaction between terephthalic acid and ethylene glycol with water as a byproduct or by transesterification reaction between ethylene glycol and dimethyl terephthalate with methanol as a byproduct. In order to obtain high molar masses polymers, solid-state polymerization is carried out. PET is one of the most important industrial polymers because of its excellent properties as tensile impact strength, chemical resistance, processability, clarity, thermal stability and others. The main applications of PET are fibers for textiles, films and bottles. Annual world PET production is around 60 millions tons. PET materials were manufactured using extrusion, injection molding and blow molding techniques. 

The process uses Ultramid T (a crystalline, semi-aromatic Nylon 6/6T), a special BASF compound which incorporates 30% glass fibre and other properties to facilitate the initiation of metal deposition and metal adhesion. The final result, after incorporating a special laser-sensitive metal complex, was Ultramid T KR4380 LS. This polymer has the high melting point of 295 "C and is equally suitable... 

Hasegawa M (2001) Semi-Aromatic Polyimides with Low Dielectric Constant and Low CTE. High Perform. Polym. 13 S93-S106. 

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