Than
đen là chất độn gia cường phổ biến cho cao su, giúp sản phẩm tăng cơ tính và
kháng mài mòn tốt. Hai thông số kỹ thuật quan trọng nhất đối với than đen là diện
tích bề mặt than đen và lượng dùng. Tuy nhiên, diện tích bề mặt lớn và lượng
dùng nhiều không nhất thiết sẽ mang lại cơ tính tốt cho cao su vì hai thông số
trên đều có mức tối ưu khi sử dụng. Phần tài liệu bên dưới sẽ trình bày cụ thể
vấn đề này.
…
Regarding tyre applications, the most important contribution of
carbon black to tyre performance is the tremendous improvement in tread wear
resistance. The amount and type of carbon black play major roles in tread wear.
Shieh and Funt [27] examined the effects of carbon black surface area,
aggregate size distribution, aggregate complexity, surface activity and the
dispersion of carbon black on wear resistance of tyre tread compounds. The
surface area of carbon black is the most important parameter affecting tread
wear. For a given carbon black loading, the wear resistance passes through a
maximum with increased carbon black surface area level as shown in Figure 5.13.
For a given carbon black surface area, an optimum loading exists as shown in
Figure 5.14. Three possible reasons are responsible for the existence of
optimum surface area and optimum loading. First, higher surface area carbon
black will create more heat during service, which may induce thermal
degradation of the compound. Second, higher surface area blacks will be more
difficult to disperse, especially at high loading. Third, higher surface area
blacks will have a smaller particle to particle spacing.
…
In this situation, the polymer chain will not have enough room
to change its configuration upon deformation or will be restricted from free
motion due to the adjacent carbon black particle, causing higher local stress.
Polymer chains will become more susceptible to break because of the higher
stress. When the elastomer coil size Dg is greater than the
particle-to-particle spacing, uniform dispersion will also be difficult to
obtain. The reason behind the optimum loading and optimum surface area for
tread wear resistance is mainly attributed to the third factor, spacing between
particles. From this point of view, going to a very high surface area black
does not necessarily result in improved wear resistance no matter how well the
black is dispersed.
…
Trích
đăng từ sách Rubber Technologist’s
Handbook, Sadhan K. De và Jim R.
White, Smithers Rapra Technology, trang 151 – 153
Nguồn:
www.books.google.com.vn
(vtp-vlab-caosuviet)
