Polymer isolation technology

VDF polymerization technology based on supercritical or liquid carbon dioxide as polymerization media has been reported. This technology offers an advantage in the polymer isolation step where a clean dry polymer is produced simply by depressurization. The residual monomer(s) and CO2 can be recycled back to the reactor. The PVDF having a multimodal molecular weight distribution is produced in CO2. Adequate CO2 density... 

Sasmal, A., Nayak, P.L., Sasmal, S., 2009. Degradability studies of green nanocomposites derived from soy protein isolate (Spi)-furfural modified with organoclay. Polymer-Plastics Technology and Engineering 48, 905—909. 

The polymers exist in saline solution as tightly coiled chains and are readily adsorbed owing to relatively low solubiUty in hard water. Subsequent injection of soft, low salinity water uncoils the adsorbed polymer chains increasing water viscosity and reducing rock permeabiUty. This technology could also be used to reduce the permeabiUty of thief 2ones adjacent to injection wells. However, mechanical isolation of these 2ones may be necessary for cost-effective treatments. 

Aqueous dispersions are alternatives to solutions of Hquid and soHd resins. They are usuaUy offered in 50% soHds and may contain thickeners and cosolvents as stabilizers and to promote coalescence. Both heat-reactive (resole) and nonheat-reactive (novolak) systems exist that contain unsubstituted or substituted phenols or mixtures. A related technology produces large, stable particles that can be isolated as discrete particles (44). In aqueous dispersion, the resin stmcture is designed to produce a hydrophobic polymer, which is stabilized in water by an interfacial agent. 

The ionic liquid process has a number of advantages over traditional cationic polymerization processes such as the Cosden process, which employs a liquid-phase aluminium(III) chloride catalyst to polymerize butene feedstocks [30]. The separation and removal of the product from the ionic liquid phase as the reaction proceeds allows the polymer to be obtained simply and in a highly pure state. Indeed, the polymer contains so little of the ionic liquid that an aqueous wash step can be dispensed with. This separation also means that further reaction (e.g., isomerization) of the polymer s unsaturated ot-terminus is minimized. In addition to the ease of isolation of the desired product, the ionic liquid is not destroyed by any aqueous washing procedure and so can be reused in subsequent polymerization reactions, resulting in a reduction of operating costs. The ionic liquid technology does not require massive capital investment and is reported to be easily retrofitted to existing Cosden process plants. 

The number of reports about hemicelluloses that have been covered by this review indicates the significantly increased importance of all types of hemicelluloses as plant constituents and isolated polymers during the last decade. Attention has been paid not only to known hemicelluloses but also to the primary structure, physicochemical, physical, and various functional properties of hemicelluloses isolated from hitherto uninvestigated plants. The efforts to exploit a variety of plant as potential sources of hemicelluloses were pointed out particularly for agricultural crops, wood wastes, as well as for by-products of pulp and rayon fiber technologies. Many studies were devoted to characterize seed-storage hemicelluloses from plants that have been traditionally applied in food and medicine of many underdeveloped countries to find substitutes for imported commercial food giuns. 

FIGURE 5.7 Phase separation in styrene-butadiene-styrene (SBS) triblock copolymer. The isolated spherical styrene domains form the hard phase, which act both as intermolecular tie points and filler. The continuous butadiene imparts the elastomeric characteristics to this polymer. MW = molecular weight. (From Grady, B.P. and Cooper, S.L., Science and Technology of Rubber, Mark, J.E., Erman, B., and Eirich, F.R. (eds.). Academic Press, San Diego, CA, 1994. With permission.)... 

A number of issues related to this reaction should be discussed. First, a polymer is rarely isolated in this form. In the early 1950s a technology was developed that has since come to be known as the one-shot process. While the technique certainly produces a capped polyol, it immediately reacts further to achieve its ultimate form (Figure 2.6, bottom). You will notice that the capped polyol still has isocyanate functionalities as end groups. Regardless of the process, these end groups must continue to react (by the addition of water and/or a catalyst) to complete the process. While this reaction produces one of the most commonly constructed polyurethanes, it is rarely isolated as an end product. 

Photochemical reactions in organic solids are important in practical fields as diverse as photography, biology, photoresist technology, polymerization, and the decomposition and stabilization of dyes, energetic materials, pharmaceuticals, and polymers [1], They have been equally important in basic research, particularly for preparing matrix-isolated reactive intermediates for spectroscopic investigation [2]. 

Regarding the improvement of overall economy of ABS and HIPS-production the polymerization of BD in the presence of styrene monomer is particularly worth mentioning (Sect. 3.3) [581-590]. By the implementation of this technology the total number of process steps and overall process complexity would be considerably reduced. In particular, the isolation of BR from the polymer solution and the drying and baling of BR at the end of the finishing process could be avoided. In addition, the preparation of BR solu-... 

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