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Absolute and Differential Dilatometry for Measurement of Unrestrained Shrinkage on Resin Curing Pages: 13 Published: Jan 1963
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View License Agreement Techniques employed for the dilatometric measurement of unrestrained volume shrinkage of a curing or cured resin are reported. The salient roles of the restrainment of reacting resins are also discussed. A versatile apparatus is described which can be used for either absolute or differential determinations. The dilatometers were equipped with a novel “net-strain balance” to detect a characteristic degree of hardening during the curing cycle. A supplementary test tube approach also was employed concurrently for this same purpose. The instruments were three-part assemblies which included: measuring tube, sample or control compartment, and glass bulb. They employed an oil column and have been found to be applicable at 200 C while thermally cycling without fatigue or significant hysteresis. The absolute method gave only the net unrestrained resin shrinkage; the more sophisticated differential approach, when combined with the absolute measurements, offered a good approximation of the complete kinetics of resin shrinkage and other properties during the curing cycle itself. The absolute technique was precise to ±0.26 per cent; although the differential approach offered a better reproducibility, difficulties were encountered in some details of the interpretation of data. The two experimental approaches tended to supplement each other and, when coupled with the concurrent evaluation of the resin's texture, they offered extremely valuable information otherwise unobtainable by present dilatometric methods. | ||
