Abstracts of Bell System Technical Papers Not Published in This Journal (01 July 1951)

Electrochemical Industry. R. M. BURNS1. Bibliography. Ind. & Engg. Chem., v. 43, pp. 301-304, Feb., 1951. Cracking of Stressed Polyethylene; Ejfect of Chemical Environment * J. B. D E COSTE 1 , F. S. MALM 1 , and V . T . WALLDER 1 . Ind. & Engg. Chem., v. 4 3 , pp. 117-121, Jan., 1951. ABSTRACT--In a number of applications for polyethylene, particularly cable sheaths and cosmetic containers, it has been found that under certain conditions failure of the polyethylene results in a cracking of the plastic. Considerable information is available to show that in an unstressed condition polyethylene is highly resistant to a wide variety of chemical environments such as alcohols, soaps, and fatty oils. 

However, when polyethylene is exposed to these environments under polyaxial stress it fails by cracking. The work described in this paper was undertaken to determine the factors involved in polyethylene cracking. A qualitative laboratory test was developed to evaluate this property and the effect of a variety of organic and nonorganic materials was studied. It was found that the higher the molecular weight of a polyethylene the more resistant it becomes to cracking, that the degree of crystallinity affects its readiness to crack, and that the addition of polyisobutylene or Butyl rubber improves crack resistance. This paper shows that useful end products, which are resistant to cracking, can be made from polyethylene. Atomic Relationships in the Cubic Twinned State* W. C. ELLIS1 and R.