Polypropylene monopolymer composites – preparation, structures and properties
Polimery 2007, No 6, 443
The group of polyethylene or polypropylene based monopolymer composites (MPC, i.e. the composites where both the matrix and the fiber are made of the same polymer) has been characterized. The subject of investigations was MPC produced either by compression molding or by pouring of immobilized iPP fiber with molten matrix - iPP film. Phase transitions of fibers were characterized using DSC method (Fig. 1 and 2). The influence of molding pressure (1 or 10MPa) during first and second heating runs has been determined as well (Fig. 6 and 7). The effects of stress and annealing temperature on fibers' shrinkage were investigated (Fig. 3-5). The morphology of composites crystallized either non-isothermally (Fig. 8) or isothermally, at temp. 145°C for 2, 3 or 6h (Fig. 9-12) has been observed using a microscope. The effects of the processing conditions of polypropylene MPC on the thickness of transcrystalline layer formed at the matrix/fiber interface, and on the value of Young's modulus (Er), taken as a criterion of evaluation of mechanical properties of the investigated materials (Fig. 13), were interpreted. The best conditions of MPC preparation, allowing reaching 100% increase in Er value of the composite in comparison with Er of initial iPP film, were proposed.
Key words: monopolymer composite, polypropylene, relative shrinkage, morphology, transcrystalline layer, Young's modulus
T. Sterzyński, I. Śledź
Polypropylene monopolymer composites - preparation, structures and properties