The response in most materials is a process called chain scission
, where the length of the chain is shortened by the thermal stress of processing.
However, the effects of radiation treatment may induce undesired effects of polymers such as chain scission
and oxidation [4,5], leading to deterioration of properties and a shorter service life.
Higher percentage of peroxide leads to predominate the polymer chain scission
reaction over the crosslinking of polymer.
There are several molecular degradation mechanisms, including oxidation, hydrolysis, chain scission
and destructive crosslinking, all of which involve permanent molecular-weight changes.
This observation may be explained using the theory that the photosensitizer of PE generally induces main chain scission
and/or cross-linking in the polymer chain.
High kinetic-energy ions striking the surface of polymer target are slowed down by electronic stopping mechanisms, resulting in chain scission
, cross- linking, bond disruption, formation of free radicals and so on (Bouffard et al.
The observed new peaks at 100[degrees]C and the increase in its intensity with X-ray dose may be due to chain scission
in PEEK polymer chain as a result of X- irradiation.
The aforementioned chemical changes mainly include chain scission
and hydrolysis [22, 36].
Quantum Yields (a) of Chain Scission
and Gas Evolution for UV Irradiation of Different Polymers Polymer UV Wavelength Quantum Yield (nm) of Scission (Gas) Poly(phenyl isopropyl 254 0.
The narrowing of the molecular weight distribution was due to the simultaneous disappearance of the high molecular weight compound due to chain scission
events and of the low molecular weight compounds as they diffuse out of the films into the medium .
of macromolecules may superpose the effect of cross linking on crystallization due to a strong nucleating effect (Ehrenstein et al, 2004) of short chain molecules.
Chemical peptizers are materials usually based on a combination of a free radical scavenger and a so-called booster material, as an effective source of oxygen radicals that serve to increase oxidative chain scission
at higher temperatures.