Fundamentals of low-pressure moulding of polymer pastes (plastisols) and thermoplastic materials

The publication reviews the reological properties of the two basic types of polymer pastes (plastisols), i.e. those showing and those not showing the thyxotropic effect. A detailed study is provided of the theory of the plastisols' low-pressure injection moulding along with the solutions to the mould filling for diversely shaped and sized runner-cavity systems. Specifically, solutions are offerd for plastisol mould fillinf with regard to particular effetcs: viscosity anomaly, non-isothermicity, structuring (gelatinizing) of the mass, pressure levelling in the cavity. The problem of frontal junction of the flows and their interdiffusion ("self-healing") is considered in connection with the method of filling one mould through two runners. Of particular technological significance is the problem of optimizing the moulding process in terms of minimizing cycle of moulding for particular combinations of the geometric characteristics of the runner and mould, under different temperatures and other factors. The methods of the engineering calculation have been experimentally tested. The experimental data proved to agree with the modern theory.