Polystyrene molecule containing benzene ring structure, hydrogen atoms on the benzene ring can be replaced by electrophilic reagents. Someone will recycle of polystyrene foamed plastic dry cleaning soluble in methylene chloride solution in under alchlor catalyst, electrophilic substitution reaction with liquid bromine flame retardants was brominated polystyrene. Bromine content can be as high as 6%, can be used as PVC, ABS, pp plastic products, such as flame retardant. Compared with other organic flame retardants, brominated polystyrene low dosage, flame retardant effect is good, don't release (2) in the process of combustion of toxic carcinogens, such as bad English and antimony trioxide and, in particular, its synergistic flame retardant effect is better, is a kind of good flame retardant performance. In the process of preparation of brominated polystyrene, performance can be goods and brominated polystyrene flame retardant was comparable to that and the cost is low. But because the amount of flame retardant itself is not very big, so this method can not meet a large number of recycling of waste PS.
Pyrolysis technology: on the one hand, can make styrene monomer cracking, namely the waste polystyrene foam plastic under heating conditions, choose appropriate catalyst cracking generation styrene monomer. In the case of styrene supply is tight, the use of polystyrene foam waste depolymerization manufacturing styrene, to meet the needs of the market, is a reasonable utilization way. The United States, France, and Japan, also made a large number of experiments, but no reports of industrialization. Depolymerization manufacturing styrene is the main problem is the conversion of styrene is lower, in a good situation but also about 70%, generally only around 40%, low conversion rate, not only affect the production cost, and cracking residue left by the back of equipment cleaning and continuous operation. On the other hand, can pyrolysis oil. Insulate foam air heating or under water vapor heating decomposition of low molecular weight hydrocarbon mixture can be obtained, by reforming catalyst decomposition, available sulfur-free gasoline and kerosene distillation fractions and part of gas. 1 kg plastic available 11 oil, the rest are mainly carbon residue. Japan more research in this respect, our country has made some achievements, it is now for industrialization.