Polyester-polyurethane, chemical

As with polyesters, the amidation reaction of acid chlorides may be carried out in solution because of the enhanced reactivity of acid chlorides compared with carboxylic acids. A technique known as interfacial polymerization has been employed for the formation of polyamides and other step-growth polymers, including polyesters, polyurethanes, and polycarbonates. In this method the polymerization is carried out at the interface between two immiscible solutions, one of which contains one of the dissolved reactants, while the second monomer is dissolved in the other. Figure 5.7 shows a polyamide film forming at the interface between an aqueous solution of a diamine layered on a solution of a diacid chloride in an organic solvent. In this form interfacial polymerization is part of the standard repertoire of chemical demonstrations. It is sometimes called the nylon rope trick because of the filament of nylon produced by withdrawing the collapsed film. 

Figure 27.8. Typical load-deflection curves for (a) latex, (b) flexible PVC, (c) polyester polyurethane (curve C) and polyether polyurethane foams (curve D). Shell Chemical Co.)...

In these polyurethane/unsaturated polyester mixtures chemical reactions and physical entanglements proceed simultaneously during processing and in the mold. The final goal of this process is the formation of a polymer composite with interpenetrating networks. These networks provide... 

Figure 14. Plots of the glass transition temperature of the soft segment phase, Tffs, Young s modulus E, and SAXS intensity, l(cps), vs. post-annealing time for a commercial polyester polyurethane (MDI/BD based), R53 (Hooker Chemical Company) (fixed s = 0.042 A 1 for SAXS data) (97).

Methacrylate-modified unsaturated polyester/polyurethane hybrid resins (as matrix resins, not foamed products) were developed by Ashland Chemical (33, 40). 

Resins, types of polymers, are the thickening and hardening agents that, without pigments, serve as colorless nail protectors resembling clear furniture lacquer. These agents include nitrocellulose (collodion) and different acrylate and polyester/polyurethane copolymers. Copolymers include chemicals such as methacrylic acid, isobutyl methacrylate, toluenesulfona-mide formaldehyde resin, phthallic anhydride/trimellitic anhydride/glycol copolymer, tosylamide/formaldehyde resin, and dimethicone copolyol. 

The chemical participation of lignin macromonomers in polymerization or copolymerization reactions has been focussed mostly on the reactivity of both types of OH groups, and hence in the synthesis of polyesters, polyurethanes and polyethers, although some research has also dealt with their intervention through the unsubstituted aromatic sites in different formaldehyde-based resins in partial replacement of phenol [58, 59]. 

Different PET chemolysis methods have been developed aimed at the production of TPA, DMT or BHET, all of them being possible monomers for the reconstruction of fresh polyesters. The exact monomer formed by PET depolymerization depends on the type of chemical agent used to break down the polymeric chains. In certain processes, the final product of PET chemolysis is a mixture of polyols, useful in the formulation of other polymers such as unsaturated polyesters, polyurethanes and polyisocyanurates. This is an interesting case of chemical recycling because the breakdown of one polymer leads to the raw materials for the preparation of a quite different class of plastics. 

Chapter 2 discusses depolymerization processes based on the chemical cleavage of polymer molecules to convert them back into the raw monomers. The latter can be reused in the manufacture of new polymers, with properties similar to those of the virgin resins. However, this alternative is mainly used for condensation polymers, and is not successful for the degradation of most addition polymers. Glycolysis, methanolysis, hydrolysis and ammonolysis are the main treatments considered. Chemical depolymerization of polyesters, polyurethanes and polyamides is reviewed. 

Selecdve chemical degradation combined with MALDI analysis was used for the characterization of polyether and polyester polyurethane (PUR) soft... 

Murgasova, R., Brantley, E.L, Hercules, D.M., and Nefzger, H. (2002) Characterization of polyester-polyurethane soft and hard blocks by a combination of MALDI, SEC, and chemical degradation. Macromolecules,... 

Synthetic fiber (man-made fiber) n. A class name for various fibers (including filaments), distinguished from natural fibers such as wool and cotton, produced from fiber-forming substances which may be (1) Modified or transformed natural polymer, e.g., alginic and cellulose-based fibers such as acetates and rayon s. (2) Polymers synthesized from chemical compounds, e.g., acrylic, nylon, polyester, polyurethane, polyethylene, polyvinyl, and carbon/graphite fibers. (3) Fibers of mineral origin, e.g., glass, quartz, boron, and alumina. 

Figure 6-9. A Xycon TS polyester-polyurethane hybrid resin from Amoco Chemical Co. was used for the body panels in this futuristic GM XT2 EL Camino. When compared to unsaturated TS polyesters, this Xycon resin with Amoco s Thomel carbon filter offers greater inherent strength, is less brittle, and requires a lower curing temperature and no postcuring.

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