Heat stability of chemically crosslinked polyethylene

✍ Scribed by M. Narkis; A. V. Tobolsky

• Publisher: John Wiley and Sons
• Year: 1970
• Tongue: English
• Weight: 400 KB
• Volume: 14
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/app.1970.070140107

✦ Synopsis

Heat stability in air of chemically crosslinked polyethylene loaded with medium thermal (MT) carbon black was studied as a function of temperature and carbon black content. Weight loss at 200' to 25OOC is practically independent of the carbon black concentration. Modulustemperature curves are changed with various heat treatment periods a t 225°C. These curves show that the rubbery modulus (amorphous state) increases with increasing the heating period, while the modulus of the partially crystalline polymer goes through a minimum and then increases. Continuous stress-relaxation and intermittent stress curves show the existence of degradation and crosslinking reactions, the latter becoming more important at higher temperatures or longer times. The degradation reaction is practically independent of the carbon black content while the crosslinking reaction at 225OC is faster with increasing M T black concentrations. It is concluded that reasonable heat stability, in the crosslinked polyethylene compounds studied, can be obtained a t temperatures lower than 150OC.