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Structure-property characterisation of ternary phase polypropylene composites
This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.An investigation to study factors controlling the structure and properties of binary- and ternary-phase polypropylene (PP) composites containing ethylene-propylene rubber (EPR) and glass beads has been carried out. The composite structure was evaluated using various techniques including SEM, DSC, XRD and DMA. While the mechanical
tests included tensile and impact measurements at ambient temperature, and a fracture toughness test based on the J-integral method carried out at -20 oC. EPR and glass beads were found to influence the structure and properties of polypropylene in different ways. Incorporation of EPR into polypropylene results in an improvement in impact strength and toughness, accompanied by a decrease in tensile strength and modulus. The opposite was found for composites containing glass beads. Polypropylene composites with balanced mechanical properties were achieved by physical blending of this polymer with both EPR and glass beads. The effect of composite structure, composition and processing variables on the properties of the ternary systems were analysed. A study of their morphology has shown that two kinds of phase structure can be formed, either a separate dispersion of the phases, or encapsulation of the filler by rubber. Factors controlling these structures are believed to be due mainly to the surface characteristics of the components. Modification of EPR by maleic-anhydride grafting results in composites with rubber encapsulation of the filler, with FTIR revealing a reaction between these phases. Composites containing unmodified EPR, on the other hand, show separate dispersion of the components. The former composites, with good adhesion at the rubber and filler interface, have noticeably higher
impact strength and fracture toughness at and below ambient temperatures, while the latter variant is characterised by higher tensile strength and modulus, accompanied by a lower impact strength. Improvements in impact strength of the composites was also
achieved by promoting adhesion between the polymer and filler interface using surfacecoated glass beads, or by increasing the number of rubber particles adhering to the glass bead surfaces using a two-step mixing technique. Results of the present study have thus shown that mechanical properties of ternary phase polypropylene composites can be adjusted, to a certain extent, by controlling their morphologies through the use of suitable functionalised materials and also by using an appropriate compounding methodology.This study is funded by the Royal Thai Government
Wood fiber reinforced multicomponent, multiphase PP composites: Structure, properties, failure mechanism
Polypropylene filled with glass spheres in extrusion-based additive manufacturing : effect of filler size and printing chamber temperature
Influence of the beta crystalline phase fraction on the mechanical behavior of polypropylene/calcium carbonate/polypropylene - graft - maleic anhydride composites
Property transitions in high-density polyethylene/maleated poly(ethylene–octene)/calcium carbonate ternary composites
Morphology prediction of ternary polypropylene composites containing elastomer and calcium carbonate nanoparticles filler
Morphology and flame-retardancy properties of ternary high-impact polystyrene/elastomer/polystyrene-encapsulated magnesium hydroxide composites
Mechanical and thermal properties of calcium carbonate-filled PP/LLDPE composite
Polymer blends typically are the most economical means to develop new resins for specific applications with the best cost/performance balance. In this paper, the mechanical properties, melting, glass transition, and crystallization behavoir of 80 phr polypropylene (PP) with varying weights of linear low density polyethylene (LLDPE) at 10, 20/ 20 wt % CaCO3, 30, 40, and 50 phr were studied. A variety of physical properties such as tensile strength, impact strength, and flexural strength of these blends were evaluated. The compatibility of these composite was examined by differential scanning calorimetry (DSC) to estimate Tm and Tc, and by dynamic mechanical analysis (DMA) to estimate Tg. The fractographic analysis of these blends was examined by scanning electron microscopy (SEM). It has been confirmed that increasing the LLDPE content trends to decreases the tensile strength and flexural strength. However, increasing the LLDPE content led to increases in the impact strength of PP/LLDPE blends. It was also found that up to 40 phr the corresponding melting point (Tm) was not effected with increasing LLDPE content. Each compound has more than one Tg, which was informed that there is a brittle-ductile transition in fracture nature of these blends, the amount of material plastically deformed on the failure surface seems to increase with the increasing the LLDPE content. And PP/LLDPE blends at temperature (23°C) showed a ductile fracture mode characterized by the co-existence of a shear yielding process; whereas at lower temperature (-20°C) the fractured surfaces of specimens appear completely brittle. The specimens broke into two pieces with no evidence of stress whitening, permanent macroscopic deformation or yielding
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