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Microstructure of cold fracture sections as an indication of changes in properties of injection‐molded nylon polymers
Author(s) -
Bobalek E. G.,
Lacson J.,
Dawson W. R.
Publication year - 1960
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1960.070030716
Subject(s) - materials science , microstructure , composite material , polymer , steaming , nylon 6 , annealing (glass) , embrittlement , softening , thermal stability , chemical engineering , chemistry , food science , engineering
The mechanical properties of injection‐molded nylon 66, nylon 610, and nylon 6 can be altered significantly by steaming or heat‐aging treatments which do not‐appear to be severe enough to cause density changes which would suggest much of a shift in the ratio of crystalline to mesomorphic polymer. However, some electron microscopy studies have demonstrated that such treatments are reflected markedly in the microstructure of fracture patterns on test bars broken at −40°C. The greater the change in microstructure, the greater was the residual effect of thermal or steam aging on the shear modulus and damping characteristics of the polymer. In general, dry annealing promoted embrittlement, particularly at low temperatures. Residual effects of steaming enhanced embrittlement at −40 and 100°C. but promoted softening at room temperature. The relative stability of room‐temperature properties to dry annealing was greatest for nylon 66, and to steaming for nylon 6.