Poly blends with polyester

Blends with good mechanical properties can be made from DMPPO and polymers with which DMPPO is incompatible if an appropriate additive, compatibilizing agent, or treatment is used to increase the dispersion of the two phases. Such blends include mixtures of DMPPO with nylon, polycarbonate, polyester, ABS, and poly(phenylene sulfide). 

Other blends such as polyhydroxyalkanoates (PHA) with cellulose acetate (208), PHA with polycaprolactone (209), poly(lactic acid) with poly(ethylene glycol) (210), chitosan and cellulose (211), poly(lactic acid) with inorganic fillers (212), and PHA and aUphatic polyesters with inorganics (213) are receiving attention. The different blending compositions seem to be limited only by the number of polymers available and the compatibiUty of the components. The latter blends, with all natural or biodegradable components, appear to afford the best approach for future research as property balance and biodegradabihty is attempted. Starch and additives have been evaluated ia detail from the perspective of stmcture and compatibiUty with starch (214). 

Polyarylates can be blended with a wide range of commercially available thermoplastics, including polyamides, polycarbonates, polyetherketones, polyesters, and poly(phenylene sulfide), thus broadening their application domain. 

This article is an overview of the novel technology of self-reinforced LCPs with polyesters, poly(ethylene terephthalate) (PET) and poly(ethylene naphtha-late) (PEN) [10-13, 21, 23], LCP/polyester blends in a polyester matrix form in situ fibrils which improve the mechanical properties. LCPs have an inherently low melt viscosity, and provide LCP/polyester blends that effectively lower the melt viscosity during melt spinning [24], and fast injection-molding cycles. The miscibility between the LCP and polyesters can be controlled by the degree of transesterification [25] in the reactive extrusion step, and fibril formation in LCP-reinforced polyester fibers has been studied. 

High-impact polystyrene (HIPS) is produced by polymerizing styrene in the presence of a rubber, usually poly(l,3-butadiene). HIPS has improved impact resistance compared to polystyrene and competes with ABS products at low-cost end applications such as fast-food cups, lids, takeout containers, toys, kitchen appliances, and personal-care product containers. HIPS as well as ABS and SMA are used in physical blends with other polymers, such as polycarbonates, polyesters, and polyamides, to improve impact resistance (Sec. 2-13c-3). 

Carboxylated polyesters were prepared by extending hydroxyl-terminated polyester segments with dianhydrides. Carboxylated polyesters which were soluble in common lacquer solvents were effective in improving the adhesion of coatings on a variety of substrates when 1-10% was blended with cellulose acetate butyrate, poly(vinyl chloride), poly(methyl methacrylate), polystyrene, bisphenol polycarbonates, and other soluble polymers. 

Table II shows the effect of the carboxyl content on the adhesive characteristics of PMDA-extended polyesters in blends with K-l polycarbonate [4,4 - (2-norbomylidene) diphenol polycarbonate] (VIII), cellulose acetate butyrate, and poly (vinyl chloride). K-l polycarbonate is an experimental polymer which, like cellulose acetate butyrate and poly (vinyl chloride), is very sensitive to adhesive changes because only 1-2% of a carboxylated...

This technology was first commercially applied to polyurethane blend [121] and patented as Rimplast (for Reactive Injection Molding), but many polymers have since been blended with polysiloxane thanks to this method polyethylene [122], polypropylene [122,123], polyamide [124-130], polyesters [128,131-133], poly(phenylene ether) [134], fluorocarbons [135] and many more. Many of them include reinforcing fillers such as fumed silica. The silicone base involved can moreover contain reactive groups such as the epoxy group [136,137]. A typical silicone base useful for these blends was de-... 

The basics of poly(ester-imide) structures and synthesis were patented in the 1960s [1,8,11-13], but also in later years companies have patented poly(ester-imide)s of various compositions and for different applications [14-24]. There are also patents where a polyester is blended with a low molecular weight imide [25], or a poly(ester-imide) is modified with amide structures [26]. These particular polymers are not reviewed here. 

The experience that the manufacturing equipment is less stressed when the polyester is formed first, and the availability of cheap polyfethylene terephtha-late) scrap, led to patents where all kind of processes were claimed to make po-ly(ester-imide) wire enamels from this polyester [97-101]. The problem is that clean, unpigmented and granulated poly(ethylene terephthalate) is needed for profitable production. There are some indications that this process is used today for industrial productions of wire enamels. Polyethylene terephthalate) is not only used as a raw material for the synthesis, but it can also be blended with a poly(ester-imide) to give a useful wire enamel [102]. 

Biodegradable polymer blends of polyanhydrides and polyesters have been used as drug carriers [59], Polyflactic acid) (PLA), polyfhydroxybutyrate) (PHB), and poly(caprolactone) (PCL), of 2000 and 50000 molecular weights were mixed with poly(sebacic anhydride) (PSA), and the properties of these mixtures were studied. Mixtures of PHB and low molecular weight PLA or PCL formed uniform blends with various amounts of PSA. These blends possess different physical and mechanical properties compared to the parent polymers. The release rate of drugs from these polymeric blends increases with the increase in the content of the rapidly degrading component, PSA. 

Polyblends in which both phases are rigid are frequently called poly alloys. Poly (phenyl oxide) is blended with impact polystyrene to improve melt flow. Complete compatibility between the two phases is rare and was observed between poly (methyl methacrylate) and poly(vinylidene fluoride) by D. R. Paul and J. O. Altamirano. Thermoplastics are added to polyesters to reduce mold shrinkage. 

In the context of this chapter, the use of thermoplastic starch in blends with thermoplastic resins is of the main interest. As shown in Table 16.11, several blends have been developed, e.g., with vinyl alcohol copolymers (EVAl), polyolefins, aliphatic polyesters such as poly-e-caprolactone (PCL) and its copolymers, or polymers of glycols (e.g., 1,4-butanediol) with succinic, sebacic, adipic, azelaic, decanoic or brassihc acids, PCL + PVC. Compatibilization is possible by amylose/EVAl V-type complexes, starch grafted polyesters, chain extenders like diisocyanates, epoxies, etc. [Bastioli et al., 1992, 1993]. 

Poly-8-caprolactone (PLC) is a synthetic, biodegradable (both linear and cross-finked) polyester with MW > 20 kg/mol. It may be processed as a thermoplastic. Owing to miscibility with PVC it is used as plasticizer and frequently blended with starch to use for films, sheets and injection molded parts, viz. Mater-Bi (see Part 16.8.1). PCL is manufacmred by Union Carbide, Daicel and Interox. Its mechanical properties are similar to these of PE [Bastioli, 1997]. 

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