Warp resistance

Mitsubishi Kasei PBT. [Mitsubishi Kasei] PBT for inj. mdding and specialty applies, (warp resistant heat resistant rigid, flame retardant). 

PET/PSF (polysulfone usually fiber reinforced) warp resistance, dimensional stabihty, stiffness, high temperature performance, chemical resistance. Apphcations include industrial process equipment, electrical connectors, and food processing equipment. 

PA/ABS high temperature warp resistance, chemical resistance, good processability, and superior appearance, automotive (body panels, under-the-hood connectors and components, fuel tanks, bearings, bushings, cams). 

Similarly the disadvantages of PC are the stress cracking and chemical sensitivity. Stress cracking can be treated as a part of impact properties and a simple solution may thus be addition of ABS or ASA. On the other hand, to improve the solvent resistance—a property that is particularly important in automobile applications—a semicrystalline polymer may be added. From Table 4.37, it is apparent that TPEs (e.g., PBT, PET) could provide that property, but they also lack warp resistance and impact strength. Hence an ideal blend for automobile application based on PC and TPEs should be impact modified with, for example, an acrylic latex copolymer. A schematic of preparation of this type of toughened blend introduced by GEC-Europe in 1979 under the tradename Xenoy is shown in Figure 4.41. 

Polysulfones are used in quite a few electrical and electronic applications. They offer a very good fit in such applications because of their good dielectric strength, low dielectric constant and low dissipation, and excellent dimensional stability. PSF and PSF blends are used in a variety of electronic connectors because of flammability resistance, dimensional stability and warp resistance, and heat resistance. Good processability is also critical in this application in that tight dimensional tolerances are required for success in connector applications. For similar reasons, PES... 

Pressure-sensitive adhesives (Meth)acrylates/styrene Core (meth)acrylates Retention of adhesive strength warp resistance... 

Excellent warp resistance Uniform shrinkage FDA accepted No ESCR ... 

Good warp resistance More stiffness than LDPE FDA accepted Lower heat deflection... 

These thermoplastic polymers are generally characterized by their toughness in respect to resistance to heat and UV exposure. Of importance also are their transparency, warp resistance, excellent flexural recovery, high elastic limits, and good electrical and mechanical properties, including outstanding creep resistance. They have as well excellent radiation and oxidation resistance. Their thermal expansion rate is close to Uiat of metal. This amorphous material is subject to environmental stress cracking, however, particularly in the presence of aromatic or aliphatic hydrocarbons. 

Celanex 6400—warp resistant, 40% glass fiber/mineral reinforced, good surface smoothness 25 0.13-0.15 0.17-0.23... 

For the preparation of lacquer ware, the oriental lacquer is usually applied on cedar wood, particularly from the Japanese cedar tree because it is the most warp resistant wood. One coat or two coats of primer, unprocessed urushi sap is applied followed by subsequent very thin layers (from twenty to forty layers) of processed "raw urushi" lacquer, one layer at the time every one or two days per application and curing. High relative humidity at the time of application and during curing is very critical it must be in the range from 65 to about 80%. ... 

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