Vulcanization compression moulding

Tyres are normally cured in a modification of the compression mould where a bladder or an inflated airbag forces and holds the green rubber stock of the tyre against the mould surface during vulcanization. This force reproduces the design of the tyre tread and the heat from the steam is introduced into the bladder to effect the vulcanization. Small size rubber expansion joints used in piping systems are moulded by compression moulding... 

Recently, it has been used as a nanofiller to impart good mechanical, thermal and electrical properties of NR nanocomposites. Ozbas et fabricated NR/ functionalized graphene sheets (FGS) nanocomposites by solution mixing. The detailed procedure was stated as follows NR compounds were completely dissolved in TFIF with the aid of a magnetic stirring bar. Then, the required amount of FGS suspended in TFIF was added to the NR solution with stirring. After mixing the FGS-NR-TFIF solution for an hour with a stir bar, THF was removed by evaporation at room temperature under vacuum. The uncured NR/FGS nanocomposites were further vulcanized by hot compression moulded technique. 

This is followed by vulcanization to obtain vulcanized composite sheets using a compression moulding in hydraulic press. The cure time for the vulcanization is generally determined using a Monsanto rheometer and optimum curing times (tgo) is calculated. The sheeted rubber compounds are conditioned at a tem- perature of 25 °C for 24 h in a closed container before cure assessment. 

Typically, the rubber (often cheap reclaimed rubber) is mixed on a mill with sulphur, diphenylguanidine (accelerator), magnesium oxide (activator) and ebonite dust (filler) to give a soft stock which is then compression moulded at 120—180°C until vulcanization is complete. 

The finished dry rubber and latex based rubber products can be vulcanized by several techniques depending on the type of rubber compound (dry rubber compound/latex compound), size of the finished product, and its shape and structure. Moulded rubber products are vulcanized by press curing using compression, transfer, or injection moulding presses. The vulcanization techniques other than moulding may be grouped into batch and continuous methods. The batch methods include the use of autoclaves, hot air/gas oven, and hot liquid/ water bath. Rubber products may be vulcanized at room temperature by cold curing either by immersion of rubber products in a carbon disulphide solution of sulphur chloride (SjCy, or by exposure to its vapour. 

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