Investigating crosslinking in blends by differential scanning calorimetry

Cook S., . and Groves S., . and Tinker A. J., . Investigating crosslinking in blends by differential scanning calorimetry. pp. 121-128. ISSN 1511-1768

Linear correlations between physical crosslink density and Tg as measured by high DSC have been demonstrated for NR BR and SBR gum vulcanisates. The dependence of Tg on crosslink density was similar for both NR and BR vulcanisates but was significantly less than that demonstrated for SBR. In the case of NR the Tg was also related to the level of sulphur in the compound and hence the efficiency of the cure. To achieve the high level of precision required in the DSC measurements it was found necessary to perform duplicate runs of each sample and to calibrate the instrument before and after each run by measuring the Tg of raw NR (-72deg.C). The correlations found between physical crosslink density and Tg for the respective polymers had been used to estimate the physical crosslink density of NR/BR and NR/SBR blends. A suitable calibration for these mesurements was found to be a raw rubber (unvulcanised) blend of the same polymer composition rather than the individual raw polymer. Estimates of physical crosslink densities of blends made by DSC compared well with measurements made by swollen state 1H NMR.

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Abstract

Linear correlations between physical crosslink density and Tg as measured by high DSC have been demonstrated for NR BR and SBR gum vulcanisates. The dependence of Tg on crosslink density was similar for both NR and BR vulcanisates but was significantly less than that demonstrated for SBR. In the case of NR the Tg was also related to the level of sulphur in the compound and hence the efficiency of the cure. To achieve the high level of precision required in the DSC measurements it was found necessary to perform duplicate runs of each sample and to calibrate the instrument before and after each run by measuring the Tg of raw NR (-72deg.C). The correlations found between physical crosslink density and Tg for the respective polymers had been used to estimate the physical crosslink density of NR/BR and NR/SBR blends. A suitable calibration for these mesurements was found to be a raw rubber (unvulcanised) blend of the same polymer composition rather than the individual raw polymer. Estimates of physical crosslink densities of blends made by DSC compared well with measurements made by swollen state 1H NMR.

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Item Type:	Article
AGROVOC Term:	Natural rubber
AGROVOC Term:	Styrene
AGROVOC Term:	Gum plants
AGROVOC Term:	Cross-linking
AGROVOC Term:	Calorimetry
AGROVOC Term:	Polymers
AGROVOC Term:	Blending
AGROVOC Term:	Calibration
AGROVOC Term:	Vulcanization
AGROVOC Term:	Crystallization
Depositing User:	Ms. Suzila Mohamad Kasim
Last Modified:	24 Apr 2025 06:28
URI:	http://webagris.upm.edu.my/id/eprint/23155

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