Preparation And Research Of Polystyrene Particles Toughened By Liner Low Density Polyethylene In Suspension Polymerization

Synthetic polymers are an important branch of essential materials in industrial and agricultural production and our daily life. However, with the development of modern science and technology, polymers are made with increasingly broad and demanding requirements. For example, polymers having both higher toughness and excellent strength, both the general characteristics of polymers and special features, not only good performance but also low prices, are expected. For the difficulty of a single homopolymer to meet a variety of requirements, chemical modification of polymer materials has become one of the most active area in polymer materials and engineering. It's an important means of polymer modification, what's more, it's an essential way for developing materials with new properties.Chemical grafting is firstly depended on the emergence of active groups in the polymer backbone by the addition of peroxide, and then decomposed into free radical copolymerization with monomers. The raw polymers used to graft with monomers are called backbone polymers, which could be homopolymers or copolymers, natural polymer or synthetic polymer. On the other hand, the monomer used in chemical grafting could be only one, or two or more simultaneously. By chemical grafting not only can we increase the compatibility between polymers but also prepare multi-functional copolymer materials. All these wonderful features of chemical grafting give it a wide range of applications in the field of polymeric materials.In this paper, LLDPE and styrene are selected as raw material and monomer respectly to prepare copolymers by chemical grafting basing on suspension. We prepared a series of LLDPE/PS ratio of polymer materials whoes performances had been characterized. Main tasks are as follows:1. By in situ suspension polymerization method and cyclohexane helping compatibilizing method we synthesised a series of LLDPE/PS ratio of copolymer materials. We discussed effects of the reaction temperature, BPO concentration, cyclohexane concentration and the mass ratio of LLDPE to St on the grating yield. The maximum grafting yield of the two system are 47.84% and 90.05%, respectively. 2. After the particles been extracted by THF:the FTIR spectrum of the copolymer showed a C-H bond of benzene variable angle vibration of exceeding the plane vibration peak at 700 cm-1 and 760 cm-1proved the existance of theLLDPE-g-PS. while it's 1H NMR spectrum of three peaks around 6.50ppm and three peaks around 7.0ppm owing to the hydrogen on the benzene ring.3. Compared to polystyrene, series TGA curves of polymer particles shifted toward the higher temperature, and the higher the quality ratio of LLDPE to PS, the higher the temperature achieving the same weight loss. The copolymer LLDPE-g-PS increased the oxidation-resistant capacity and its thermal stability.4. The performed LLDPE-g-PS copolymer can effectively compatibilize the system. At the same LLDPE/PS weight ratio, the higher the grafting degree, the better the compatibility, the more uniform phase dispersion. The greater the LLDPE/PS weight ratio, the better the compatibility of the copolymer.5. After chemical modification, the mechanical properties of the prepared material increased with the increase of both the maximum elongation and elongation at break which were proportional with the mass ratio and the grafting degree. This showed that the prepared polymer had not only rigidity, but also certain toughness.