Interface modification and characterization in three-component polymer blends

The effect of interface characteristics on the properties of three-component polymer blends comprising PP/EVOH/mica and PP/EVOH/glass beads (GB) was investigated (polypropylene-PP, ethylene-vinylalcohol-EVOH). The systems selected are based on the binary PP/EVOH immiscible blend representing a semi-crystalline apolar polymer (PP) and a semi-crystalline highly polar copolymer (EVOH), where PP serves as the matrix. A series of the binary and three-component blends with varying compositions was chosen to study the effect of the molding procedure, i.e. compression versus injection molding. The structures observed by SEM analysis consisted of the filler particles engulfed by the EVOH phase, with some of the minor EVOH component dispersed within the PP matrix. The effects of silane treatment (GB/EVOH interface) and compatibilization, using a maleated-PP compatibilizer (PP/EVOH interface), were studied in relation to the generated structures and properties. The compatibilizer was added in a unique procedure by which the encapsulated GB/EVOH structures were preserved. The characterization methods used included morphology by Scanning Electron Microscopy, thermal properties and crystallization behavior by Differential Scanning Calorimetry, mechanical properties by tensile testing, and dynamic characteristics by Dynamic Mechanical Thermal Analysis. The work has shown that structure-performance relationships in the three-component blends can be varied and controlled.