Polymer degradation polyester resins

Manfredi, L. B., Rodriguez, E. S., Wladyka-Przybylak, M., and Vazquez, A. Thermal degradation and fire resistance of unsaturated polyester, modified acrylic resins and their composites with natural fibres, Polym. Degrad. Stabil. 2006, 91, 255-261. 

A condensation polymer is one in which the repeating unit lacks certain atoms which were present in the monomer(s) from which the polymer was formed or to which it can be degraded by chemical means. Condensation polymers are formed from bi- or polyfunctional monomers by reactions which involve elimination of some smaller molecule. Polyesters (e.g., 1-5) and polyamides like 1-6 are examples of such thermoplastic polymers. Phenol-formaldehyde resins (Fig. 5-1) are thermosetting condensation polymers. All these polymers are directly synthesized by condensation reactions. Other condensation polymers like cellulose (1-11) or starches can be hydrolyzed to glucose units. Their chemical structure indicates that their repealing units consist of linked glucose entities which lack the elements of water. They are also considered to be condensation polymers although they have not been synthesized yet in the laboratory. 

Solid organophosphite antioxidant that provides color stability, reduces polymer degradation, and improves gas fading performance in many resins. It may be used in polyethylene, polypropylene, polystyrene, polyesters, elastomers, PVC and thermoplastics. 

Cusack,P.A.,Heer, M.S., andMonk,A.W. (1997) Zinc Hydrorgfstarmate as an Alternative Synergist to Antimony Trioxide in Polyester Resins. Polym. Degrad. Stab., 58, 229. 

Bora et al. [63] prepared nanocomposites based on graphene oxide (GO) and unsaturated polyester resin (UPR). They verified that the incorporation of 3 wt% of GO improved the major degradation temperature of polyester from 230 to 285 °C. This improvement in thermal stability was attributed to the strong interaction between GO and UPR which restricts the mobility of the polymer matrix segments at the interface. The interaction may be attributed to the formation of hydrogen bonding between oxygen functionality on reinforcement and polymer or probably dipolar interactions between the two components. 

The influence of the value of the entrance angle in the capillary on the extrusion process was also showed for other polymer melts PE, PP, PB, PI [747], polyester resins [746,762], PS [763], As the thermal and oxidative factor were kept constant and some of the geometrical characteristics had constant values, the process of mechanochemical degradation can develop in the entrance zone in... 

Kandola, B.K. Nazar6, S. Horrocks, A.R. Thermal degradation behaviour of flame retardant unsaturated polyester resins incorporating functionalised nanoclays, in M. Le Bras, C.A. Wilkie, S. Bourbigot, S. Duquesne, and C. Jama, Eds., Fire Retardancy of Polymers New Applications of Mineral Fillers. Royal Society of Chemistry, London, 2005, pp. 147-160. 

The early hot melt adhesives were not strictly definable as rubber-based adhesives. Most rubber polymers such as natural rubber and random SBR are of such molecular weight and structure that they do not melt readily to a workable coating consistency at a temperature below which thermal degradation and decomposition take place. Certain synthetic polymers, however, lend themselves to the formulation of a wide range of hot melt adhesive compositions. Polyamide and polyester resins, ethylene-vinyl acetate (EVA) copolymers, ethylene-ethyl acrylate (EEA) copolymers, low molecular weight polyethylene and amorphous polypropylene, and certain vinyl ethers have found application in hot melt adhesives. These adhesives have found wide use in packaging, industrial, and construction applications. 

The packaging (qv) requirements for shipping and storage of thermoplastic resins depend on the moisture that can be absorbed by the resin and its effect when the material is heated to processing temperatures. Excess moisture may result in undesirable degradation during melt processing and inferior properties. Condensation polymers such as nylons and polyesters need to be specially predried to very low moisture levels (3,4), ie, less than 0.2% for nylon-6,6 and as low as 0.005% for poly(ethylene terephthalate) which hydrolyzes faster. 

Noncrystalline aromatic polycarbonates (qv) and polyesters (polyarylates) and alloys of polycarbonate with other thermoplastics are considered elsewhere, as are aHphatic polyesters derived from natural or biological sources such as poly(3-hydroxybutyrate), poly(glycoHde), or poly(lactide) these, too, are separately covered (see Polymers, environmentally degradable Sutures). Thermoplastic elastomers derived from poly(ester—ether) block copolymers such as PBT/PTMEG-T [82662-36-0] and known by commercial names such as Hytrel and Riteflex are included here in the section on poly(butylene terephthalate). Specific polymers are dealt with largely in order of volume, which puts PET first by virtue of its enormous market volume in bottie resin. 

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