EVA prospect For the domestic market in terms of medium density polyethylene (MDPE) seems to be a new term, but because the performance between high density polyethylene (HDPE) and low density polyethylene (LDPE) between the two, while maintaining the rigidity of HDPE and LDPE, flexibility, creep resistance, in both the merits.soon, absolute the advantage in the gas pipes, water pipes, and communication cable sheath, so more and more attention by the market. The unique properties of established market position: MDPE because of its good resistance to environmental stress cracking resistance, weldability and long service life etc. in recent years, the rapid development of application, the amount of increase quickly, MDPE is considered to be the world's most suitable communication cable, fiber optic cable with sheath material. In foreign countries, the development of MDPE is synchronized with LDPE and HDPE. Dow Chemical Co., Ltd. adopts I nsite Technology　 In Europe, MDPE has established a dominant position in the air distribution and water distribution pressure tube market. MDPE has the great potential to enter the metal and PVC territory in the field of large diameter gas distribution (outside diameter 100mm), gas pipeline (outside diameter 300mm?or?above) and water distribution pipe (outside diameter 200mm?or?above). In terms of water distribution, the amount of MDPE in Europe is 160 thousand tons. The pace of domestic R & D is accelerating: the development of MDPE resin in domestic market is lagging behind, and there are not many products in the market. Most cable sheathing manufacturers can only use the way of blending. Maoming petrochemical and Zhongyuan ethylene company introduced MDPE products in all density polyethylene production plant, such as tube material DGDA-2401 and DNDD-7152 for rotary molding, but they yield very little. The introduction of new Yanshan Petrochemical Company 200 thousand tons / year production of LDPE EXXON chemical company in 3 grade of MDPE (117, 151, 157), the density values in the range of 0.9280g/cm ~ 0.9355g/cm 3, has produced two grade 117 and 151 600 tons of products, but the product density is low, and non copolymer products, environment resistant stress cracking performance is poor, not suitable for the production of pressure pipes such as gas pipes etc.. In 2004, Shanghai Petrochemical Co launched the 250 thousand ton / year polyethylene plant with the Nordic chemical Shuangfeng polyethylene technology, which can produce PE100 pipe special material, but the product grading work can also be completed by 2004, which means that the raw materials currently used in China still need to import. The market demand potential is considerable: at present, the field of MDPE in China includes wire and cable sheathed materials, water conveyance pipelines, buried gas pipelines and agricultural irrigation hoses (belts), and the demand for them is bigger and bigger. Most manufacturers use HDPE plus LDPE MDPE communication cable, optical cable sheath material, the annual output of 30 thousand tons; the gas pipe material has good welding resistance, rapid transfer of environmental stress cracking resistance and cracking, the manufacturers are using imported MDPE materials; agricultural irrigation hose (with) applications in the field of is MDPE, in order to reduce the price of production cost control, which are currently only a few manufacturers using imported MDPE, most of the domestic LDPE and LLDPE, individual manufacturers to add a small amount of HDPE blends to improve the stiffness of the world; the best recognized hose reel automatic sprinkler irrigation machine is a kind of suitable for China's national conditions, PE hose the winding machine not only to withstand the bending, tensile stress and internal pressure, but also resistance to ground friction, sun and rain, alternating hot and cold comprehensive effect, foreign The MDPE tube has been developed to synchronize the service life of the hose with the sprinkler. In the middle and late 80s of China, this kind of sprinkler was developed. And with the matching quality of the MDPE hose has not yet been successfully developed reports, the market demand is about 20 thousand - 30 thousand tons / year. The development of West to east gas transmission project and the west to East power transmission project and the construction of urban natural gas transmission pipeline network, urban and rural water conveyance and gas pipeline network construction and the position of China's agricultural giants all depict a brilliant prospect for the PE family's new favorite -- MDPE and its products. But at present, for the domestic market, domestic users either from the rational?or?perceptual knowledge of MDPE is not enough, but through propaganda and development of MDPE brand strength, believes MDPE has been gradually known at the same time, also for the construction and development of the country to make more outstanding contributions. [2-3] EMA In recent years, special products have become the focus of HIPS product development. The newly developed HIPS products can compete with engineering plastics in some applications, there is much higher than the quality of the products, instrumentation and consumer electronics products HIPS is one of the growing market, including small instruments, and the internal parts of the inner wall of the refrigerator, air conditioning, TV shell parts, business machines and video cassette recording. The special grade HIPS resin has replaced the high price engineering plastics in many fields. An ultra-high impact strength and high temperature HIPS has even been used as automotive interior parts. GPPS GPPS plastic is a general class of polystyrene (GPPS) polystyrene (PS) is composed of styrene monomer (SM) polymerization, can be formed by a variety of synthetic methods of polymerization, polymerization industry at present mainly by bulk polymerization and suspension polymerization. The English name of polystyrene is Polystyrene, PS (hereinafter referred to as PS). PS is a thermoplastic noncrystalline resin, which is mainly divided into universal polystyrene (GPPS, commonly known as benzene), impact resistant polystyrene (HIPS, commonly known as benzene modification) and foamed polystyrene (EPS). PVC Polyvinyl chloride (PVC) waterproofing membrane The cauldron is the main equipment, which is made of stainless steel?or?enamel lined with steel kettle, equipped with agitator and heat transfer jacket for controlling temperature,?or?internal cooling pipe, reflux condenser and so on. In order to reduce the production cost, the volume of the reactor has expanded from several cubic meters to a dozen cubic meters. The largest volume has reached 200 cubic meters. When the polymerizer is used many times, it needs to be descaled. PVC, made of polyvinyl alcohol and cellulose ether as suspended stabilizer, is generally loose, porous and large in surface area. It is easy to absorb plasticizer and plasticizing. 2. One of the earliest methods of industrial production of PVC by emulsion polymerization. In emulsion polymerization, water and vinyl chloride monomer, and adding sodium dodecyl sulfonate surfactant as emulsifier, monomer dispersed in the aqueous phase and emulsion, water soluble potassium persulfate and ammonium persulfate as the initiator, can also lead to the system of "oxidation reduction". Polymerization process and different suspension method. There are also polyvinyl alcohol as emulsifying stabilizers, twelve alkyl mercaptan as a regulator, sodium bicarbonate as a buffer. There are three kinds of polymerization methods: batch method, semi continuous method and continuous method. The polymerization products are latex like, and the particle size of the emulsion is 0.05 ~ 2 m, which can be directly applied?or?dried by spray to form a powdery resin. The polymerization period of emulsion polymerization is short and easy to control. The resin obtained has high molecular weight and even degree of polymerization. It is suitable for PVC paste, artificial leather?or?impregnated products. The formula of emulsion polymerization is complex and the content of impurities is high. (3) the polymerization device of bulk polymerization is more special, mainly composed of a vertical prepolymerization kettle and a horizontal polymerizer with a frame type agitator. Two stages of polymerization are carried out. The monomer and initiator first polymerized 1h in the pre polymerization kettle to generate seed particles, and the conversion rate was 8% to 10%. Then it entered the second stage polymerizer and added the monomer with the same amount of prepolymer to continue polymerization. The conversion rate is 85% to 90%, the residual monomer is discharged, and the finished product is then crushed and sifted. The particle size and shape of the resin are controlled by the stirring speed, and the reaction heat is produced by the reflux of the monomer. The production process of this method is simple, the quality of the product is good and the production cost is low. PVC modification method