Hiện
nay, trên thị trường có rất nhiều loại chất hóa dẻo dùng cho cao su. Phần tài
liệu dưới đây sẽ cung cấp cho người đọc những hướng dẫn chung để chọn được chất
hóa dẻo phù hợp cho một ứng dụng cụ thể.
…
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.
…
Trích
đăng từ sách Handbook of Specialty
Elastomers, Robert C. Klingender,
CRC Press, 2008, trang 407 – 408
(vtp-vlab-caosuviet)
