Chất
hóa dẻo được phối trộn vào hỗn hợp cao su, hỗ trợ quá trình gia công. Phần tài
liệu dưới đây sẽ giới thiệu về chất hóa dẻo và phân loại chúng theo thành phần
hóa học và tính năng.
…
Plasticizer:
Any material (primarily liquid) that is added to a compound to facilitate
easier mixing, extruding, molding, and curing through modification of the basic
physical properties of the uncured and cured compound (e.g., viscosity,
hardness, modulus, low-temperature flex).
Monomeric
types: It is common to characterize plasticizers generally as either polymeric
or monomeric. For our purposes here, monomerics are all plasticizers (glycol
esters, monoesters, diesters, and triesters), which are not polymeric.
Viscosities range from 4 to 400 cps.
Polymeric
types: This group is technically comprised of polyesters with viscosities from
400 to 200,000 cps. To create polyester, a glycol rather than an alcohol is
reacted with a fatty acid. For purposes of this chapter we exclude the very
high polymers used as polymeric plasticizers such as Nipol 1312, a
low-molecular weight NBR elastomer.
Synthetic
plasticizers: These are chemically reacted, man-made, from highly specified
components to form a plasticizer with consistently reproducible properties.
Esters comprise the major portion of this category.
Low-temperature improvement: This is achieved through the use of
plasticizers primarily related to their molecular weight as measured
by viscosity. A rating system has been applied to a number of plasticizers in Table
12.1. Compatibility is also a factor to be considered, hence the ratings in
both polar and semipolar elastomers is given.
High-temperature
performance: It is also related to the molecular weight of the plasticizer as
measured by volatility, as may be seen in Table 12.2.
The relative solubility of a number of plasticizers is also given, which
relates to their extractability in various fluids in service. Both of these
factors must be considered when designing a specialty elastomer compound.
…
Trích
đăng từ sách Handbook of Specialty
Elastomers, Robert C. Klingender,
CRC Press, 2008, trang 389
(vtp-vlab-caosuviet)
