Polyblend, polyurethane

Certain polymers have come to be considered standard building blocks of the polyblends. For example, impact strength may be improved by using polycarbonate, ABS and polyurethanes. Heat resistance is improved by using polyphenylene oxide, polysulphone, PVC, polyester (PET and PBT) and acrylic. Barrier properties are improved by using plastics such as ethylene vinyl alchol (EVA). Some modem plastic alloys and their main characteristics are given in Table 1.2. 

To understand the mechanism of polyblending, experiments have been carried out with polymeric solution. W. Borchard and G. Rehage mixed two partially miscible polymer solutions, measured the temperature dependence of the viscosity, and determined the critical point of precipitation. When two incompatible polymers, dissolved in a common solvent, are intimately mixed, a polymeric oil-in-oil emulsion is formed. Droplet size of the dispersed phase and its surface chemistry, along with viscosity of the continuous phase, determine the stability of the emulsion. Droplet deformation arising from agitation has been measured on a dispersion of a polyurethane solution with a polyacrylonitrile solution by H. L. Doppert and W. S. Overdiep, who calculated the relationship between viscosity and composition. 

TPU of hardness 55-70 Shore A are based on a polyblend of a polyurethane with a rubber nitrile, optionally with a suitable amount of additives [69]. 

Lee, K. H., H. Y. Kim, Y. J. Ryu, K. W. Kim, and S. W. Choi (2003c). Mechanical behavior of electrospun fiber mats of poly(vinyl chloride)/polyurethane polyblends. Journal of Polymer Science Part B Polymer Physics 41(11) 1256-1262. 

The photodegradation of polyurethane elastomeric adhesives and its polyblends with poly(vinyl chloride), poly(vinyl alcohol), poly(vinyl acetate) and poly(vinyl acetate-co-vinyl chloride) [652], and rubbers based on poly-(diene urethanes) and poly(ether urethanes) has also been reported [1062]. 

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