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SYNTHETIC PLASTICIZERS
1. There are no effective low-temperature synthetic ester plasticizers with viscosities above 50 cps.
2. High-temperature volatility/aging is directly related to the MW of the plasticizer. Low viscosity/low MW equals poor aging and high viscosity/high MW equals good aging.
3. Extraction and swell characteristics are dependent on the chemistry of the extract and plasticizer and the MW. For example, high MW polymerics are relatively immobile and extraction fluids tend to be absorbed by the plasticizer (volume swell), whereas monomerics are much more mobile and easily exchange places with extracts and usually create more or less volume shrinkage depending also on the chemistry involved.
4. There is a hold-in characteristic of some plasticizers—especially high MW types—effectively increasing compatibility is related not only to size of the molecule (see 3 above) relative to a co-plasticizer or swell medium but also to the polarity of the plasticizers involved (see also castor factice below).
VULCANIZED VEGETABLE OIL/FACTICE
1. In highly polar elastomers use castor-based factice for highest compatibility, best stress–strain properties, and lowest volume swells.
2. Compression set is adversely affected by all sulfur-cured factice and should be monitored carefully.
3. Improve compatibility of highly plasticizer-loaded compounds by substituting 0.5–1.5 phr of factice for each phr of liquid plasticizer.
4. Depending on the formulation and loading, factice can have positive or negative effects on heat-aged properties in semipolar or polar compounds where use of factice is indicated.
RUBBER PROCESS OILS
1. Use hydrocarbon process oils sparingly in specialty elastomers.
2. Never use the paraffinic types in polar or semipolar elastomers.
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Trích đăng từ sách Handbook of Specialty Elastomers, Robert C. Klingender, CRC Press, 2008, trang 407 – 408
(vtp-vlab-caosuviet)