Creep, Long-Time Tensile and Flexural Fatigue Properties of Melamine and Phenolic-Plastics Materials

Abstract

This paper reports work done to compare the tensile creep, long-time tensile strength, and dynamic flexural fatigue-strength properties of some commercial melamine and phenolic-plastic materials. Tensile-creep data for woodflour-filled phenolic and cellulose-filled melamine indicate that these plastics exhibit similar characteristics, that is, the rate of elongation at 500 hr is essentially the same for the two materials. Likewise, the total elongation at 1000 hr is of the same order of magnitude for each of the materials. Similarly, asbestos-filled phenolic and asbestos-filled melamine show comparable tensile-creep properties. The long-time tensile strength of the cellulose-filled melamine is superior to that of the woodflour-filled phenolic material. The melamine has a long-time tensile strength of about 67 per cent of the short-time value (A.S.T.M. D638-41T), as compared with a value for the phenolic of approximately 36 per cent. Results of the repeated flexural-stress tests indicate that the woodflour-filled phenolic plastic is slightly superior to the cellulose-filled melamine, the endurance limit for the phenolic being approximately 4000 psi, or 34 per cent of the short-time static flexural strength, and for the melamine 3000 psi or 31 per cent of the short-time static flexural strength. Further tests of this nature would be desirable for the purpose of studying the effect of other fillers and formulations.