Chemistry of the latex prevulcanisation process. Part 1. Migration of reactants from the solid phase into rubber particles

Porter M., . and Rosemaze R., . and Sapi’ai A. R., . Chemistry of the latex prevulcanisation process. Part 1. Migration of reactants from the solid phase into rubber particles. pp. 85-101.

High-ammonia natural rubber latex has been prevulcanised with a zinc diethyldithiocarbamate-accelerated sulphur system in which either the sulphur or the accelerator was incorporated into the latex from a solid deposit on the wall of the containing vessel. The occurrence of prevulcanisation under these conditions is best explained on the thesis that both the accelerator and sulphur dissolve in the aqueous serum of the latex before migrating into the rubber phase. Heating the uncompounded latex in a sulphur-coated flask and subsequently compounding it with accelerator in a separate vessel and then heating it also causes prevulcanisation demonstrating that the presence of other ingredients is not necessary for sulphur to dissolve in the latex. However the degree of prevulcanisation is limited by the quantity of sulphur dissolved. Similarly latex can be prevulcanised by heating it in a ZD EC-coated flask (in the presence of diethylamine) compounding it with a sulphur dispersion in a separate step and reheating it. In this case the degree of prevulcanisation is not limited presumably because ZDEC is continuously regenerated as crosslinking proceeds. Aqueous leaching of films deposited from a prevulcanised latex usually causes increases in film modulus and particularly strength. In the experiments described aqueous leaching had very little effect on these or other stress-strain properties.

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Abstract

High-ammonia natural rubber latex has been prevulcanised with a zinc diethyldithiocarbamate-accelerated sulphur system in which either the sulphur or the accelerator was incorporated into the latex from a solid deposit on the wall of the containing vessel. The occurrence of prevulcanisation under these conditions is best explained on the thesis that both the accelerator and sulphur dissolve in the aqueous serum of the latex before migrating into the rubber phase. Heating the uncompounded latex in a sulphur-coated flask and subsequently compounding it with accelerator in a separate vessel and then heating it also causes prevulcanisation demonstrating that the presence of other ingredients is not necessary for sulphur to dissolve in the latex. However the degree of prevulcanisation is limited by the quantity of sulphur dissolved. Similarly latex can be prevulcanised by heating it in a ZD EC-coated flask (in the presence of diethylamine) compounding it with a sulphur dispersion in a separate step and reheating it. In this case the degree of prevulcanisation is not limited presumably because ZDEC is continuously regenerated as crosslinking proceeds. Aqueous leaching of films deposited from a prevulcanised latex usually causes increases in film modulus and particularly strength. In the experiments described aqueous leaching had very little effect on these or other stress-strain properties.

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Item Type:	Article
AGROVOC Term:	Natural rubber
AGROVOC Term:	Latex
AGROVOC Term:	Vulcanization
AGROVOC Term:	Zinc
AGROVOC Term:	Sulphur
AGROVOC Term:	Organic compounds
AGROVOC Term:	Chemistry
AGROVOC Term:	Solid content
AGROVOC Term:	Heating
AGROVOC Term:	Cross-linking
Geographical Term:	Malaysia
Depositing User:	Ms. Suzila Mohamad Kasim
Last Modified:	28 Apr 2025 04:32
URI:	http://webagris.upm.edu.my/id/eprint/23453

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