Specialty polymer resin blends

Fluoropolymers are notoriously immiscible with any other polymer. Usually, they are dispersed in blends of engineering and specialty polymers either to improve processability or to induce lubricity and abrasion resistance. Examples of the PC/Specialty resin blends are listed in Table 1.68. 

Addition of PPE/PS to POM was used to improve processability, HDT, and mechanical properties [Ishida and Masamoto, 1974]. More recently, POM with a Lewis acid was incorporated into PPE/PA blends to improve compatibilization and induce high heat and impact resistance [Takayanagi et al., 1994]. POM blends with specialty polymers are formulated either to take advantage of POM (the resistance to abrasion), or of the specialty resin e.g., to improve stiffness and wear resistance by incorporation of PEEK or PEI) [Suzuki and Nagahama, 1987]. POM is miscible with polyvinylphenol, PVPh, thus addition of PVPh to blends of POM with COPO compatibilizes the system [Machado, 1993]. 

The crystalline polymers such as PPS, LCP, PEEK offer the additional advantages of high solvent resistance. Due to the inherently high cost of the specialty polymers, very few blends have been developed for commercial applications. The only driving force for the development of even the few blends of specialty polymers has been the desire to reduce the cost of the base resins by blending with lower cost engineering plastics, although this invariably results in a lower DTUL. Nevertheless, a few commercial blends of specialty polymers exist and their properties will be discussed below ... 

In the following text examples of recycled polymer blends will be given, first for the commodity, then for the engineering and specialty resin blends. Whenever possible, the methods of compatibilization and re-compatibilization should be the same. In particular, when recycling is to reproduce the original blends performance, the same compatibilization method is essential. For this reason, support of the blends manufacturer should be ascertained. 

Most specialty resins are processed at temperatures that limit the possibility of blending them with PE. The PE/specialty resin blends usually contain low concentration, < 5 wt%, of either component. Addition of PE improves the processability, surface finish, chemical, solvent, and impact resistance. Addition of specialty polymer to PE may improve rigidity and processability (viz. PE/LCP). Examples are given in Table 1.46. 

The commodity resin blends represent the major part of the hlend market, hut their market share varies from one country to another. For example, while in Canada 70% of linear low density polyethylenes are blended, in the United States only about 30% benefit from this technology. Furthermore, styrenics blends (viz., HIPS, ABS, blends with SAN, MSAN, SMA, etc.) that constitute a large part of the market, are described in only a few entries. On the other end of the performance spectrum are the specialty blends. Reading today s patent literature one may get the impression that blends with snch resins as polyetherimide, polyamideimide, or hqnid crystal polymers, LCP, are of principal indnstrial interest. These blends also are poorly represented in this EDCPB volume. 

In recent years the focus has been on the high performance, specialty resins. For example, polyetherimide, PEI, was commercialized in 1983. In tlie ensuing two years its blends with most engineering and specialty polymers were patented. Since 1990 PEI C blends, Ultem LTX , have been available from GEC. 

The specialty resins are expensive, produced in relatively small volumes either for a specific application or looking for a market niche. Their Tg > 200°C and modulus > 3 GPa. In 1991 the total world consumption of polysulfones (PSE) and polyethersulfones (PES) was 8.5 kton. Blends of the following polymers are known polyfluorocarbons, polysiloxanes, sulfur-containing polymers (PPS, PPSS, PES, and PSF), polyetherk-etones (PEK, PEEK, PEKK), polyimides (PI, PEI, and PAI), PAr, COPO, polyphosphazene (PHZ) and LCP. 

In addition, different types of the rheological analyses performed on polymer alloys and blends are listed in Appendix 7.1 — the table provides information on systems studied, conditions and assumptions, as well as it gives basic references to the topic. Appendices 7.2, 7.3, and 7.4 summarize the rheological information of blends comprising, respectively, commodify, engineering, and specialty resins. 

The blend comprised at least two sulfone polymers, e.g., PES and PSF, and at least one non-sulfone polymer (e.g., PS, PPE, PEI, PC, PA, PEST, PP, or PE). The nucleating agent was either talc, mica, silica, Zn-stearate, Al-stearate, Ti02, or ZnO. The foams were used as insulation for high temperature structural applications. Since in the preceding part PPS blends with PSF were described, in Table 1.71 examples of PSF blends with other specialty resins are listed. 

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