Relationship between Morphology and Mechanical Properties of Highly Filled Magnesium Hydroxide/Polypropylene/ Ethylene-Octene Copolymer Composites

摘要

The addition of high amount of fillers would unavoidably deteriorate the mechanical properties of polymer resin, especially elongation at break, due primarily to the poor interfacial adhesion between the two components. However, in certain application fields such as the material for wire and cable use, an elongation at break larger than 150% is basically required. Therefore, a great deal of effort has been made to solve this problem, and it is a pity that no perfect project has been found yet. In this study, ethylene-octene copolymer (POE) and magnesium hydroxide (Mg(OH)2) will be employed to modify PP simultaneously. POE is highly elastomeric, and tolerates high filler loadings while retaining its flexible properties. Mg(OH)2 is commonly used in polyolefins as excellent nontoxic and smoke- suppressing halogen-free flame retardants. This compound acts in both the condensed phase and the gas phase. However, its low effectiveness makes it necessary to incorporate at a very high loading in polymers to achieve an acceptable low flammability. In our previous study, it was found that the addition of 55 wt% Mg(OH)2 could notably reduce the heat release rate of the PP resin but fail to maintain an acceptable mechanical properties. For this reason, we focus on co- continuous PP/POE blends and investigate the effect of high-loading fillers on the mechanical properties and morphology of the composites. We expect that the formation of a co-continuous morphology can achieve good mechanical properties, especially the elongation at break. The relationships between phase structure and mechanical properties of PP/POE/Mg(OH)2 will be discussed in detail.