Polymerization technologies

Slurry (Suspension) Polymerization. This polymerization technology is the oldest used for HDPE production and is widely employed because of process engineering refinement and flexibHity. In a slurry process, catalyst and polymer particles are suspended in an inert solvent, ie, a light or a... 

Solution Polymerization. Two solution polymerization technologies ate practiced. Processes of the first type utilize heavy solvents those of the second use molten PE as the polymerization medium (57). Polyethylene becomes soluble ia saturated C —hydrocarbons above 120—130°C. Because the viscosity of HDPE solutions rapidly iacrease with molecular weight, solution polymerization is employed primarily for the production of low mol wt resias. Solution process plants were first constmcted for the low pressure manufacture of PE resias ia the late 1950s they were later exteasively modified to make their operatioa economically competitive. 

An independent development of a high pressure polymerization technology has led to the use of molten polymer as a medium for catalytic ethylene polymerization. Some reactors previously used for free-radical ethylene polymerization at a high pressure (see Olefin polymers, low density polyethylene) have been converted to accommodate catalytic polymerization, both stirred-tank and tubular autoclaves operating at 30—200 MPa (4,500—30,000 psig) and 170—350°C (57,83,84). CdF Chimie uses a three-zone high pressure autoclave at zone temperatures of 215, 250, and 260°C (85). Residence times in all these reactors are short, typically less than one minute. 

Solution Polymerization. Two types of solution polymerization technologies are used for LLDPE synthesis. One process utilizes heavy solvents the other is carried out in mixtures of supercritical ethylene and molten PE as a polymerization medium. Original solution processes were introduced for low pressure manufacture of PE resins in the late 1950s subsequent improvements of these processes gradually made them economically competitive with later, more advanced technologies. 

The original SBR process is carried out at. 50° C and is referred to as hot polymerization. It accounts for only about 5% of aU the mbber produced today. The dominant cold polymerization technology today employs more active initiators to effect polymerization at about 5°C. It accounts for about 85% of the products manufactured. Typical emulsion polymerization processes incorporate about 75% butadiene. The initiators are based on persulfate in conjunction with mercaptans (197), or organic hydroperoxide in conjunction with ferrous ion (198). The rest of SBR is produced by anionic solution polymerization. The density of unvulcanized SBR is 0.933 (199). The T ranges from —59" C to —64 C (199). 

DuPont Sclair solution polymerization technology, 20 196 DuPont—University Interface Model,... 

The annual production of various polymers can be measured only in billion tons of which polyolefins alone figure around 100 million tons per year. In addition to radical and ionic polymerization, a large part of this huge amount is manufactured by coordination polymerization technology. The most important Ziegler-Natta, chromium- and metallocene-based catalysts, however, contain early transition metals which are too oxophiUc to be used in aqueous media. Nevertheless, with the late transition metals there is some room for coordination polymerization in aqueous systems [1,2] and the number of studies published on this topic is steadily growing. 

Miniemulsion Polymerization Technology edited by Vikas Mittal. Forthcoming summer 2010. 

The book is a ready reference for the background information as well as advanced knowledge regarding the applications of miniemulsion polymerization technology. 

Polymers at interfaces are an important part of a large number of polymeric technological applications. The orientation, specific interactions, and higher order structures of amphiphilic molecules at a quasi two- dimensional plane form the basis of a variety of interesting phenomena [3-6], Scheme 3.1 shows a schematic representation of this behavior. 

Today s commercially available BR grades can be classified according to the type of polymerization technology and initiators/catalysts used ... 

The majority of literature on Nd-mediated diene polymerization is concerned with polymerization in solution. This technology was developed at an early stage of Nd polymerization technology and many basic principles elaborated for solution processes have been adopted in the development of Nd-BR production. Therefore, the Polymerization in Solution and various aspects associated with it are reviewed first. Other polymerization technologies such as polymerization in bulk (or mass), suspension (or slurry) and gas phase are addressed in separate Sects. 3.1 and 3.2 at a later stage. 

DuPont and Dow use solution polymerization technology to produce LLDPE resins. The process is based on continuous polymerization of ethylene with 1-octene in cyclohexane at about 250°C and 1200 psi. The catalyst is again Ziegler type. Residence time is of the order of several minutes. The catalyst is deactivated by treatment with an alcohol or complexing agent such as acetyl-acetone, and adsorbed on a silaceous adsorbent before stripping the solvent. The Stamicarbon (Dutch State mines) process is similar to the DuPont process, and it uses a short-residence-time solution process for HDPE production. 

Description The BP/Lummus styrene polymerization technology for the manufacture of regular and flame-retardant grades of EPS is a one-step batch suspension reaction followed by continuous dewatering, drying and size classification. 

Gas-phase polymerization technologies exclusively using supported catalysts are being employed more extensively in large-scale polyalkene production. Supported catalysts are also penetrating into the production of speciality polymers. They must therefore be regarded as the most perspective variant. 

A aubstantial amount of recent experimental data demonstrate that the model of styrene emulsion polymerization (1.2) on which the quantitative theory is based (, is not capable of adeqiiate interpretation of polymerization in many real systems. An attempt to use the theoretical relationships to describe polymerization of such industrially important monomers as vluyl acetate, vinyl chloride, alkylacrylates, as well as copolymerization of common monomers with functionally substituted ones, leads to a conclusion that the theory disregards some of the essential factors of the process. Therefore, this theory cannot be a foimdatlon for polymerization technology of the above monomers to be modernized and automatized. 

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