Addition-type polyamides

The reaction is essentially an addition polymerization, but can be considered to be the condensation polymerization of AB-type polyamide. 

Several classes of P- and N-containing polymers have been reported in literature. These include polybenzimidazoles, polyester-imides, polyamide-imide, polyanhydride-imides, polyurethanes, polyamides, and polymaleimide-amines. Heretofore, phosphorus-containing bisimide resins have received little attention. Bisimide monomers, which cure by addition-type polymerization without the elimination of volatile products, are suitable as matrix resins for fabrication of graphite-fabric reinforced composite materials. 

Fig. 77. Effectiveness of the action of inhibitors of the type of phosphites and sulfides, introduced into the polymer (with an addition of polyamide) in a 0.5% concentration T = 200°C P02 = 200 mm Hg. 1) Polymer without additives 2) stable polymer 3) ionol pyro-catechol phosphite 4) polygard 5) SAG-6 6) polysulfide.

In addition to the semicrystalline nylons, which comprise the vast majority of commercial resins, nylon is also available in an amorphous form that gives rise to transparency and improved toughness at the expense of high temperature properties and chemical stress crack resistance. Table 2 shows the properties of some different polyamide types. 

Polyamide Resins. Another class of polyamide resins, in addition to the Hquid resins used as epoxy hardeners, are the thermoplastic type, prepared generaHy by the condensation reaction of polyamines with polybasic fatty acids. These resins find use in certain hot-melt adhesives, coatings, and inks. Diamines, typicaHy EDA (233), are the principal amine reactant however, tri- and tetramines are sometimes used at low levels to achieve specific performance. 

Limited testing on chlorine sensitivity of poly(ether/amidel and poly(ether/urea) thin film composite membranes have been reported by Fluid Systems Division of UOP [4]. Poly(ether/amide] membrane (PA-300] exposed to 1 ppm chlorine in feedwater for 24 hours showed a significant decline in salt rejection. Additional experiments at Fluid Systems were directed toward improvement of membrane resistance to chlorine. Different amide polymers and fabrication techniques were attempted but these variations had little effect on chlorine resistance [5]. Chlorine sensitivity of polyamide membranes was also demonstrated by Spatz and Fried-lander [3]. It is generally concluded that polyamide type membranes deteriorate rapidly when exposed to low chlorine concentrations in water solution. 

Most addition polymers are formed from polymerizations exhibiting chain-growth kinetics. This includes the typical polymerizations, via free radical or some ionic mode, of the vast majority of vinyl monomers such as vinyl chloride, ethylene, styrene, propylene, methyl methacrylate, and vinyl acetate. By comparison, most condensation polymers are formed from systems exhibiting stepwise kinetics. Industrially this includes the formation of polyesters and polyamides (nylons). Thus, there exists a large overlap between the terms stepwise kinetics and condensation polymers, and chainwise kinetics and addition (or vinyl) polymers. A comparison of the two types of systems is given in Table 4.1. 

Fully aromatic polyamides are synthesized by interfacial polycondensation of diamines and dicarboxylic acid dichlorides or by solution condensation at low temperature. For the synthesis of poly(p-benzamide)s the low-temperature polycondensation of 4-aminobenzoyl chloride hydrochloride is applicable in a mixture of N-methylpyrrolidone and calcium chloride as solvent. The rate of the reaction and molecular weight are influenced by many factors, like the purity of monomers and solvents, the mode of monomer addition, temperature, stirring velocity, and chain terminators. Also, the type and amount of the neutralization agents which react with the hydrochloric acid from the condensation reaction, play an important role. Suitable are, e.g., calcium hydroxide or calcium oxide. 

PVC, polyamides, unsaturated crosslinked polyesters, ABS, and wood . Di- and tri-benzotriazole photostabilizers, such as (874) and (875) are synthesized from 2-nitro-benzenediazonium salts and an excess of 1,3-dihydroxybenzene or 1,3,5-trihydroxybenzene <85Mi 40i-0l>. The dibenzotriazole derivatives (874b and 875b) can be used as polymerizable acrylic UV absorbers <84PB237>. A few or/Ao-urethane and -trimethylsilane substituted 2-phenylbenzotriazoles (876 and 877) show similar photostabilization activity . Weather resistance of low-density polyethylene is improved by the addition of a benzotriazole-type photostabilizer <90M140i-04>. 

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