ISSN:
0021-8995
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
,
Physics
Notes:
The kinetic characteristics and the reaction conditions of photocross-linking of low-density polyethylene (LDPE) in the melt have been studied using benzophenone (BP) and its derivatives such as 4-chlorobenzophenone (4-CBP) as photoinitiator and triallyl cyanurate (TAC) as cross-linker. The efficiency of the photoinitiated cross-linking system LDPEBP-TAC and various factors affecting the cross-linking process, such as photoinitiator and cross-linker and their concentrations, irradiation time, temperature, and atmosphere, and UV light intensity were examined extensively by determining gel content, IR, and UV spectra. It has been found (i) that LDPE samples of 2-3 mm thickness are easily cross-linked to a gel content of about 70% with a UV-irradiation time of about 15 s under optimum conditions; (ii) that the photoinitiating system of a suitable initiator combined with a multifunctional cross-linker such as 4-CBP-TAC can enhance the efficiency of photocross-linking reactions, especially by increasing the initial rate of cross-linking; (iii) that photocross-linking of LDPE should be carried out in the melt, which increases the penetration of UV light by decreasing the scattering by crystallites, and (iv) that the rate of cross-linking is proportional to the square of the light intensity. An increase in light intensity can decrease the concentration of photoinitiator required to reach a certain rate of cross-linking. The photocross-linking of polyethylene is promising for industrial applications. © 1993 John Wiley & Sons, Inc.
Additional Material:
11 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/app.1993.070480412
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