Flame‐retarding effects of dialkyl‐p‐vinylbenzyl phosphonates in copolymers with acrylonitrile

Abstract

Several dialkyl-p-vinylbenzyl phosphonates have been synthesized and free-radically copolymerized with acrylonitrile to give copolymers with phosphorus contents ranging from 1 to 14 wt%. The flammability and thermal degradation characteristics of these copolymers have been assayed by limiting oxygen index and thermogravimetric methods. It has been found that, despite the negative effect of the vinylbenzyl entity upon the stability of polyacrylonitrile, the incorporation of a small percentage of phosphonate has a significant effect on retarding combustion of the copolymers. The differing effects of the polymerizable function (backbone group) and the pendant phosphonate on thermal stability and flame retardance are deconvoluted by comparison of the behaviours of the acrylonitrile-dialkylp-vinylbenzyl phosphonate copolymers with the corresponding acrylonitrile-styrene copolymers. The increased flammability and reduced char formation in acrylonitrile-styrene copolymers, compared with those of polyacrylonitrile itself, are shown to recover in the presence of pendant phosphorus groups, and the particular effects of these groups are discussed.

Preparation of phosphorus‐containing and nitrogen‐containing durable flame retardant polyacrylonitrile fabric via surface chemical modification

“…At the same time, a wider and lower exotherm peak ranging from 220°C to 320°C appears, and the T p (281°C) of FR‐PAN is lower than that of PAN. This is most likely because the decomposition of the phosphate group in the pendent chain to phosphorus‐containing acids can accelerate the cyclization of the cyano . On the other hand, the pendent amino‐containing and phosphorus‐containing group will weaken the interaction between cyano groups, and restrain the cyclization exothermic reaction.…”

“…Modacrylic fiber is the only industrialized copolymerization fire retardant PAN fiber; nevertheless, modacrylic fiber is greatly restricted because the fiber can release toxic hydrogen halide and amounts of smoke during combustion. Halogen‐free comonomers can be used to copolymerize with acrylonitrile to improve the fire retardant performance of acrylonitrile polymers. However, the copolymerization flame retardant method also has some defects, such as higher synthetic cost, difficulty of copolymerization with acrylonitrile, and poor spinnability of the fire retardant acrylonitrile copolymers .…”

“…Halogen‐free comonomers can be used to copolymerize with acrylonitrile to improve the fire retardant performance of acrylonitrile polymers. However, the copolymerization flame retardant method also has some defects, such as higher synthetic cost, difficulty of copolymerization with acrylonitrile, and poor spinnability of the fire retardant acrylonitrile copolymers . Plasma grafting is a relative complex and difficult technique to operate, which limits the application of this technique to some extent.…”

“…However, the fire retardant property of the carboxyl group‐containing acrylonitrile copolymers is far less than that of the phosphorus‐containing acrylonitrile copolymers . It is reported that the phosphorus content in acrylonitrile copolymers, polyacrylonitrile fiber, and derived fabrics is over 3 wt%; good flame retardant performance will be obtained. Therefore, to improve the flame retardant properties of polyacrylonitrile fiber and its fabric, it is essential to introduce phosphorus‐containing groups into polyacrylonitrile fiber.…”

Thermal degradation kinetics of poly(O,O‐diethyl‐O‐allylthiophosphate‐co‐acrylonitrile) in nitrogen

“…These monomers include vinylidene chloride, vinyl chloride, and their bromide analogues. 1 Another type of monomer that has been used for the preparation of flame-retardant PAN is phosphorus-containing compounds. [2][3][4][5][6][7] However, there are few reports on the study of fire-retardant PAN made of monomers containing both sulfur and phosphorus.…”