Poly high conversion polymer

The chemical resistance and excellent light stabiUty of poly(methyl methacrylate) compared to two other transparent plastics is illustrated in Table 5 (25). Methacrylates readily depolymerize with high conversion, ie, 95%, at >300° C (1,26). Methyl methacrylate monomer can be obtained in high yield from mixed polymer materials, ie, scrap. 

Bulk Polymerization. This is the method of choice for the manufacture of poly(methyl methacrylate) sheets, rods, and tubes, and molding and extmsion compounds. In methyl methacrylate bulk polymerization, an auto acceleration is observed beginning at 20—50% conversion. At this point, there is also a corresponding increase in the molecular weight of the polymer formed. This acceleration, which continues up to high conversion, is known as the Trommsdorff effect, and is attributed to the increase in viscosity of the mixture to such an extent that the diffusion rate, and therefore the termination reaction of the growing radicals, is reduced. This reduced termination rate ultimately results in a polymerization rate that is limited only by the diffusion rate of the monomer. Detailed kinetic data on the bulk polymerization of methyl methacrylate can be found in Reference 42. 

Because of the experimental difficulties involved, there are relatively few reliable Cp values available in the literature. The values that are available [Eastmond, 1976a,b,c Ham, 1967] for any one polymer often vary considerably from each other. It is often most useful to consider the small model compound analog of a polymer (e.g., ethylbenzene or isopropylbenzene for polystyrene) to gain a correct perspective of the importance of polymer chain transfer. A consideration of the best available Cp values and those of the appropriate small-model compounds indicates that the amount of transfer to polymer will not be high in most cases even at high conversion. Cp values are about 10-4 or slightly higher for many polymers such as polystyrene and poly(methyl methacrylate). 

Acrylamide polymers in aqueous solution undergo thermal hydrolysis and cyclic imide formation. Acrylate, acrylamide and cyclic imide functional groups were detected when a poly(acrylamide) is heated at 150°C in water. The formation of intramolecular imide has been reported in literature. Moradi-Araghi, Hsieh and Westerman reported the formation of cyclic imide in acid, neutral and slightly basic media at 90° C.7 In acidic media, imide formation is favored. In neutral and basic media, both hydrolysis to acrylate and imide formation do occur, but hydrolysis is the dominant reaction. We speculate the high conversion of amine to amide is the result of transamidation, amidation and the nucleophilic addition of the amine to the glutarimide intermediate (Reaction 1). 

Poly (ethylene terephihalate) and nylon-6,6 manufacture are homogeneous bulk step-growth reactions. The molecular weight of the polymer produced is limited by the high viscosity of the reaction mixture at very high conversions. Post polymerization techniques such as that described in connection with reaction (5-39) can be used to increase the polymer molecular weight for some applications. 

A former application of aniline, now mainly displaced, was conversion to hydroquinone. The hydroquinone is the starting point for a process developed by Rose at ICI s Plastics Division. The outcome, a high melting polymer, resistant to oxidation, is poly(ether-ether-ketone), or PEEK, made from hydroquinone. This high-performance thermoplastic, with fiber reinforcements such as Kevlar, is used in plastic kettles, nose-cones of missiles and engines. 

The main interest of this work concerns the question whether the reaction conditions can also be applied to the block copolymers. The experiments showed that no modifications of the reaction conditions had to be made. Two polystyrene-block-1,2-poly butadiene with a PS/PB ration of 89/11 and a molecular weight of55 000 g/mol for PSPB I and 118 000 g/mol for PSPBII were used as starting materials. High conversion as well as no change in polydispersity is found for both polymers (Table I). This ratio will lead to a lamellar morphology of the block copolymers if phase separation occurs. 

In our particular type of step-addition polymerisation, monomers, dimers, trimers, oligomers and polymers are the reactive species which participate in the chain growth. Initially, the monomers react with monomers and give dimers, dimers react with monomers and dimers and give trimers and tetramers, respectively. The high MW polymer is formed only in the last stages of the poly addition reaction, at high conversion rates. Chain transfer and termination reactions are absent. 

Well-defined rod-coil diblock or triblock copolymers can be obtained from conjugated macro-initiators by CRP. In each case the synthetic route requires the mono- (for diblock) or di-functioimalization (triblock) of a previous conjugated polymer. For this purpose, this last one needs to be properly end capped with a high conversion and further transformed into a macro-initiator. Many examples can be found in the literature, such as poly(para phenylene vinylene)... 

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