Flex-poli

The bonding properties of (Ti02) have been used for size-reinforcing of glass fibers so that they adhere to asphalt or to a PTEE—polysulfide mixture to impart enhanced flex endurance (434—436). Poly(vinyl alcohol) (PVA) solutions mixed with sucrose can be cross-linked with the lactic acid chelate and used generally for glass-fiber sizing (437). 

PESA can be blended with various thermoplastics to alter or enhance their basic characteristics. Depending on the nature of thermoplastic, whether it is compatible with the polyamide block or with the soft ether or ester segments, the product is hard, nontacky or sticky, soft, and flexible. A small amount of PESA can be blended to engineering thermoplastics, e.g., polyethylene terepthalate (PET), polybutylene terepthalate (PBT), polypropylene oxide (PPO), polyphenylene sulfide (PPS), or poly-ether amide (PEI) for impact modification of the thermoplastic, whereas small amount of thermoplastic, e.g., nylon or PBT, can increase the hardness and flex modulus of PESA or PEE A [247]. 

Table 1. Flex and hole energies, and their ratios of Poly (vinyl acetate) PVAc), Poly(vinyl chloride) (PVC), and Polystyrene...

PEDOT with and without the dopant PSS has been the most commonly used conductive polymer for SWNT composites. De et al prepared composite films by vacuum filtration from aqueous dispersions with PEDOT PSS as the matrix and both arc and HiPCO SWNTs as the filler. The optimal performance was observed for a 80 nm thick film containing 60 wt /o arc SWNTs, with a sheet resistance of 80 Q sq at 75 /o transmittance. Electromechanical testing showed these films to be stable under flexing and cycling. Later, a modified PEDOT copolymer with enhanced solubility, perchlorate-doped poly(3,4-ethylenedioxythiophene)-Z /ock-poly(ethyleneox-ide) (P-PEDOT-b-PEO) was used to disperse SWNTs and then to fabricate conductive nanocomposites via vacuum filtration method.The sheet resistance of the composite film was approximately 600 Q sq with 80 /o transmittance. 

Figure 7.2. Scanning electron microphotograph of cellulose-polyacrylo-nitrile-poly(butyl methacrylate) copolymer fabric sample before (A) and after (B) flex abrasion (24,000 cycles).

Herrero and Acosta (80) investigated the microstmcture of poly(ethylene oxide)-poly[(octafluoropentoxy)(trifluoroethoxy)phosphazene] blends. Limited miscibility of both components was inferred, based on the observed shift of the components glass-transition temperatures. Wycisk and co-workers (81) prepared membranes from blends of sulfonated poly[bis(3-methylphenoxy)phosphazene] with polyimides, polyacrylonitrile, and Kynar FLEX PVDF. Morphology, electrochemical performance, and methanol permeabilities of the membranes were then evaluated as part of a program to investigate such blends in direct methanol fuel cells. The polymers were immiscible and a domain-type structure was observed. The best compatibility resulted when the tetrabutylammonium or sodium salt of the polyphosphazene was used (82). 

Poly(ester ester)s have better heat, light and oil resistance and lower flammability than poly(ether ester)s. They are inferior in other properties, such as hydrolytic stability, low temperature behavior, load bearing and heat-distortion temperature. Poly(ester ester)s exhibit broader melting range, lower rate of crystallization, higher melt viscosity at low shear rates, as well as inferior melt stability and flex life [9]. 

Properties of Polyimide Films. Table 61.8 shows major properties of typical poly-imide films, Kapton H and Apical AV. These have good mechanical properties and provide excellent performance as base substrate films and coverlay films in dynamic flexing appUca-tions.They have flame-retardant characteristics, and it is not difficult to achieve Underwriters Laboratories (UL) flame class 94-V-O or 94-VTM-O. The largest disadvantage of polyimide film is its higher cost compared to other common plastic films such as PET. 

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