Degrading type

Graft or block copolymers are expected to be formed via process (28) (i) and (ii), respectively, depending on whether the polymer Ap is of a crosslinking type or a degrading type. No homopolymerization occurs in... 

Other elements of weather and outdoor exposure can interact with UV radiation to accelerate degradation in degradable types of plastics. They include humidity, salt spray, wind, industrial pollutants, and atmospheric impurities such as ozone, biological agents, and temperature. The wavelengths that have the most effect on plastics range from 290 to 400 nm (2,900 to 4,000 A). 

It is important to recognize that polypropylene, which is the major constituent of TPO, is a typical degrading-type polymer in the radiation chemistry of polymers, i.e., once a free radical is formed on a polymer chain, the free radical unzips the chain rather than cross-links. CASING effect was first found with polyethylene [24], which is a typical cross-linking-type polymer. The same CASING effect, however, could not be anticipated with the treatment of the degrading-type polymers because the degradation of substrate polymer enhances the extent of weak boundary layer. 

Electron Beam Polymers POSITIVE - DEGRADING TYPE... 

Table 2 Reaction rates scaled in terms of the rate constant. (Here, the scale refers to chemical degradation type reactions lasting from minutes to decades. For simplicity, the scale relates to a first order rate constant, and is, therefore, exponential)...

The peculiar factor that determines the behavior of polymer under irradiation is radiochemical yield. It depicts the number of events that occur as the result of the absorption of 100 eV, G. The greater the values of G, the less stable the polymer [12]. The consequences of irradiation conditions related to the tremendous radiochemical yields place various macromolecular materials in different groups of stability mainly degradable type and manly crosslinkable type [12, 18]. 

Inhibition of the allyl-degradative type chain-transfer reaction can... 

An examination is made of the mechanisms of rubber degradation, types of antiozonants and antioxidants used in rubbers, and the mechanisms by which they prevent polymer degradation. 10 refs. 

Degradation Type Main Rate Determining Parameters... 

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