Moulding of rubbers

Report 27 Injection Moulding of Rubber, M.A. Wheelans, Consultant. 

In the moulding of rubber products, the operation of opening and closing the press rapidly in the early stages of the cure to drive out any trapped air. 

The usual practical range of moulding variables during moulding of rubber are ... 

The dithiocarbamates have the pentacoordinate binuclear structure (44). The diamyl- and diethyl-dithiocarbamate complexes have been found to inhibit the hardening of asphalt, but the effect appears too weak to be useful.127 The latter complex is an effective antioxidant for polyethylene,128 polypropylene,129 polystyrene,130 poly(methyl methacrylate)130 and an isoprene-styrene copolymer.131 The di-n-butyldithiocarbamate complex is important in the vulcanization and injection moulding of rubber,132 as a stabilizer against photolytic and thermal degradation. 

Compression moulding of rubbers is not essentially different from that of thermosets. The starting material is a blend of a rubber, vulcanisation ingredients and... 

Polymers and Structural Composites in Civil Engineering, L. Hollaway, University of Surrey. Injection Moulding of Rubber, M.A. Wheelans, Consultant. 

Styrene copolymer. The di-n-butyldithiocarbamate complex is important in the vulcanization and injection moulding of rubber, as a stabilizer against photolytic and thermal degradation. 

Wan and Isayev (1996) examined a hybrid approach of control-volume finite-element and finite-difference modelling of injection moulding of rubber compounds. The effect of vulcanization on viscosity and yield stress during cavity filling is reported. On comparing two versions of the modified Cross viscosity models - with and without the effect of cure - the use of a viscosity model that accounts for the cure was found to improve the accuracy of the cavity-pressure-prediction models. When the modified Cross model was further extended to include the yield stress and was implemented in the simulation program a significant improvement in the prediction of cavity pressure was obtained in the case of low injection speed. 

This section will discuss issues relating to the injection moulding of rubbers, specifically to the moulding of liquid silicone rubber (LSR) which is of large commercial interest. Firstly however, a quick introduction to rubber materials is given. 

Whelans, M. Advances in injection moulding of rubber. Progress of Rubber Technol, Vol. 48, Plastics and Rubber Institute, London, 1979, pp. 195-199. 

J-C. Deng, Basic Study of Injection Moulding of Rubber Compounds. Ph.D. Thesis, The University of Arkron. (1990). 

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