Experimental Studies On Pyrolysis Characteristics Of The Plastic HIPS Containing Brominated Flame Retardants

Due to the continual increase of the amount of WEEE （Waste Electrical and ElectronicEquipment） and the toxic materials contained in, such as heavy metal and brominated flameretardants, WEEE has became one of the most hazardous waste sector. For the plastics inWEEE, pyrolysis is promising recycling method. The pyrolysis oil can be used as fuel orchemical feedstock. But there are some noxious orginac bromianted compounds in thepyrolysis oil which must be removed using debromination methods that could be performedduring the process of pyrolysis or after the pyrolysis. Therefore, the pyrolysischaracteristics of flame retarded HIPS （Br Sb HIPS: High impact polystyrene containingdecabromodiphenyl oxide and Sb₂O₃, Br HIPS: Containing decabromodiphenyl oxide only）,co pyrolysis with （Polypropane） PP or （High Density Polyethylene） HDPE and thedebromination effect of PP and HDPE were studied.First of all, the pyrolysis behavior of Br Sb HIPS and the mixture of Br Sb HIPS andPP or HDPE were studied using a thermogravimetry. The results showed that the pyrolysisprocess of Br Sb HIPS mainly occurred in the temperature range of320468℃and itsDTG curve had three peaks that corresponded to its three reaction stages. WhenBr Sb HIPS was mixted with PP or HDPE, they would interact and produce compoundswith large molecular weight that led to decrease of weight loss rate, in the second pyrolysisstage.Second, the pyrolysis experiments of Br Sb HIPS were performed in a fixed bedreactor at410℃, and the pyrolysis oil and char were analyzed with advanced instruments.It was found that pyrolysis of Br Sb HIPS produced6.1%Char，33.5%Wax，45.2%Oil and15.2%Gas. The pyrolysis oil of Br Sb HIPS mainly comprised of toluene, ethylbenzeneand styrene and so on. When PP or HDPE were mixed with Br Sb HIPS, the productsdistribution would change largely and it would also influence the yields of compounds inpyrolysis oil. When30%PP mixed with Br Sb HIPS, it could reduce the amount of organic bromine in pyrolysis oil to38%of the original value. In addition, the Br HIPS,without Sb₂O₃presence, produced more abundant oil products. Its pyrolysis oils includedproducts that are not existed in Br Sb HIPS oil products, such as α methylstyrene.At last, the activation energy of Br Sb HIPS that was solved with method ofFlynn Wall Ozawa changed from103307kJ/mol during the pyrolysis process. Thekinectic model that contains three successive reactions could simulate real pyrolysis processexcellently.