System for vacuum pouring of epoxy tensile and impact specimens with a study of the behavior of these specimens at 77 K and 293 K

Abstract

The purpose of the investigation was to establish a suitable technique for vacuum pouring of epoxy test specimens and to study the behavior of these specimens at 77 K and 293 K. A series of tensile and impact tests was conducted using specimens made from the following resins: Epon 828, Epon 871, and Epon curing agent Z. These materials are of general interest to designers of magnets for cryogenic service. Tests of the specimens were carried out at 77 K and 293 K. The 77 K data indicate that tensile strength increases proportionally with the increase of Epon 871 relative to Epon 828. When the mixture includes more than 90% Epon 871, impact testing at 293 K becomes practically impossible due to the rubbery condition of the material. However, when tested at 77 K, this same mixture evinces high tensile strength. When optimum data are sought over a wide range of temperatures, 77 K to 293 K, it appears that a mixture of 70% Epon 871, 30% Epon 828 with 13 pph of curing agent Z or 50% Epon 871, 50% Epon 828 with 15 pph curing agent Z offers the best compromise in tensile strength, modulus of elasticity, andmore » impact resistance.« less