1, Rubber phase glass transition temperature ASA impact strength
According to the types of rubber phase copolymerized, ASA homologues have ABS, AES (ethylene-propylene copolymer rubber as the rubber backbone) .Studies show that the low Tg of rubber relative to the SAN has a better impact, several rubber phase Tg is as follows: Therefore, the room temperature impact strength of the same rubber content in the order of ABS> AES> ASA, low temperature impact resistance is ABS, AES, followed by ASA worse.
2, the rubber grafting rate of ASA performance
The toughening mechanism of ASA resin mainly absorbs the impact energy by inducing the silver fringe, and the key factor that affects the silver fringe is the interface binding force between the SAN and the rubber phase, the weak interface bonding force, Impact strength.
This is why ABS blends with nitrile butadiene rubber (SAN) and blends with SAN are much more expensive than ABS blends with SAN blends grafted with SAN The reasons for the direct blend in the ABS.
Because after grafting, SAN resin and rubber interface adhesion increases, but the grafting rate exceeds a certain extent, the impact strength no longer increases, but a downward trend, it is because with the increase of rubber backbone graft rate, rubber elasticity May decline, and reduce the rubber produced by the effect of entropy change.
In addition, the grafting rate increases and the fluidity of the resin decreases. Therefore, considering the balance between the mechanical properties and the processing properties of the ASA resin, a proper grafting ratio should be controlled.
SAN types, molecular weight on the performance of ASA:
Improve the molecular weight of the blended SAN, ASA resin impact strength increased mobility decreased; selection of high acrylonitrile SAN blend, the resin tensile strength, impact strength, melt strength can be increased, decreased mobility, chemical resistance Improved character.
Therefore, changing the type and grade of SAN blended with the grafted ASA powder enables the production of products with different physical properties to diversify the grades.
3, rubber content on the performance of ASA
In general, when the blended SAN grades are fixed, increasing the rubber content, tensile strength, flexural strength, heat distortion temperature, MI decreases, while the impact strength, tensile elongation at break increases, so by adjusting the rubber content, Preparation of universal and high impact ASA resin.
4, ASA resin aging resistance
The wavelength of the light wave that causes the aging of the SAN resin phase in the ASA is 250 to 290 nm. This wavelength band is less in the daylight and can act on the SAN by adding suitable UV absorbers, light stabilizers and UV screening agents such as carbon black Good protective effect.
For the rubber phase, light waves with a wavelength of less than 700 nm in the sunlight have sufficient energy to act as a photo-oxidant for butadiene, but only light waves less than 300 nm act as a photo-oxidant for the acrylate. UV absorbers have the option of absorbing light waves In general, it can effectively absorb the light wave of 270 ~ 400nm.
So for ABS, only by adding carbon black, titanium dioxide and other screen agents can play a significant protective effect of the resin, UV absorber play a protective effect is limited.For the ASA, adding an appropriate amount of light stabilizers and UV absorbers, pigments , You can play a good protective effect.