Impact resistance rating

Thermal Oxidative Stability. ABS undergoes autoxidation and the kinetic features of the oxygen consumption reaction are consistent with an autocatalytic free-radical chain mechanism. Comparisons of the rate of oxidation of ABS with that of polybutadiene and styrene—acrylonitrile copolymer indicate that the polybutadiene component is significantly more sensitive to oxidation than the thermoplastic component (31—33). Oxidation of polybutadiene under these conditions results in embrittlement of the mbber because of cross-linking such embrittlement of the elastomer in ABS results in the loss of impact resistance. Studies have also indicated that oxidation causes detachment of the grafted styrene—acrylonitrile copolymer from the elastomer which contributes to impact deterioration (34). 

T and are the glass-transition temperatures in K of the homopolymers and are the weight fractions of the comonomers (49). Because the glass-transition temperature is directly related to many other material properties, changes in T by copolymerization cause changes in other properties too. Polymer properties that depend on the glass-transition temperature include physical state, rate of thermal expansion, thermal properties, torsional modulus, refractive index, dissipation factor, brittle impact resistance, flow and heat distortion properties, and minimum film-forming temperature of polymer latex... 

We can nucleate crystallization from the melt by incorporating finely ground inorganic crystalline compounds such as silica. Nucleation of injection molded nylons has three primary effects it raises the crystallization temperature, increases the crystallization rate, and reduces the average spherulite size. The net effect on morphology is increased crystallinity. This translates into improved abrasion resistance and hardness, at the expense of lower impact resistance and reduced elongation at break,... 

Type designation Nominal thickness, mm Thickness tolerance, mm Wear resistance cycle Ball impact resistance, a mm MD CD Boiling water resistance J rating 5 Radiant heat resistance, s ... 

Independently of the strain rate and the test temperature, the toughness of the material depends on its ability to absorb or dissipate energy, and this requires chain mobility. In the glassy state the energy-absorbing mechanism is related to the p relaxation. Therefore, impact resistance... 

The catalyst support impacts the rate of a catalyzed reaction, the reaction pathway (quantities and species of intermediates and products) and the resistance of the catalyst to deactivation. In DBCP reactions, powders had higher rate constants than beads, presumably due to reduced mass transfer limitations alumina yielded a faster rate than C, which had a faster rate than PEI/silica. Sorptive capabilities of the supports may also play an important role Kovenklioglu found that supports which sorbed 1,1,2-TCA more strongly had higher reaction rates, and Farrell concluded that TCE sorption to Fe cause higher reaction rates on Pd/Fe electrodes than on pure Pd electrodes. It is also clear that supports influence reaction products, but the correlation between a given support and pathways/products it promotes is not yet understood. The choice of support can also affect its resistance to deactivation this implies that catalyst supports may be tailored to maximize activity over the long term. 

The Role of Rubber Modification in Improving High Rate Impact Resistance... 

---