Q. Write short notes on fabrication of rubber objects.

Sol. Fabrication of Rubber: in the row condition rubber is composed of molecules of great length and molecular weight. Although it is thermoplastic in this condition its plasticity can be improved by working or masticating the rubber in air at room temperature. This has the effect of partially oxidizing rubber resulting in fragmentation of the large molecules into more plastic but smaller ones. For various objects different process are used which are described below.

(1)                         Extrusion: the machine used for extrusion of rubber is sometimes called a tuber which is used for extruding continuous length of tread and side wall stock for tyres. The continuous strips are later cut into proper length to make tyre.

(2)                         Calendaring: the process is used for making continuous sheets of rubber or impregnating fabric with rubber. If the circum perennial speed of the rolls is faster than the speed of the cloth the process is called fractioning and rubber compound is wiped into the voids of the fabric.

(3)                         Moulding: moulding of rubber parts is accomplished mainly by compression moulding and transfer moulding.

(4)                         Dipping and Electrode position: both are used to produce shapes such as gloves face masks and balloons from latex. The same way as metals are deposited from solutions.sss