On improving flow ability of glass fibre reinforced phenolic composites

Reinforcing glass fibre decreases the flow ability of phenolic composites, thus making the use of such composites in injection moulding process very difficult. This paper presents an optimal flow increaser A. The experiment about A shows: (1) Flow ability at low temperature of phenolic impregnated glass fibre is improved because (a) the plasticization of the melted flow increaser liquid decreases the viscosity of impregnated glass fibres, and (b) extension of chain span of phenolic and slowing down of the curing reaction due to the use of flow increaser prolongs the flow time. (2) Fast curing at high temperature achieved. This is because flow increaser promotes curing of phenolic and thus speeds up curing reaction. (3) 2-3%wt. of flow increaser is optimal for best effects. (4) Under conventional press moulding process conditions, the properties of glass fibre reinforced phenolic are: (a) impact strength 56 kJ/m² and flexural strength 172 MPa (no increaser) and (b) impact strength 66kJ/m² and flexural strength 201 MPa (increaser added). (5) For 2-3%wt. of flow increaser added, the thermal and electrical properties, though less satisfactory, still meet the user's requirements.