Jie Song    - research student -

Abstract: Functionalized poly(propylene-co-ethylene) (PPE) made via reactive extrusion dramatically improved the performance of their blends with poly(methyl methacrylate) (PMMA). Adhesion, compatibility, modulus, hardness and scratch resistance were all increased for blends with functional PPEs compared to non-modified PPE, greatly expanding the applications of polyolefins. Three types of functional PPEs including maleic anhydride grafted PPE (PPE-MA), hydroxyl group grafted PPE (PPE-OH) and secondary amine group grafted PPE (PPE-NHR) were melt blended with PMMA at different compositions and with PMMA of different molecular weights. Compatibility of each functional PPE with PMMA was compared by investigating the binary blends using mechanical (nano-indentation, nano-scratch and tensile tests), morphological (scanning electron microscopy with image analysis, particle size analysis) and adhesion tests. Compatibility of functional PPEs with PMMA is confirmed consistently from various tests and ranked in a decreasing order as follows: PPE-NHR > PPE-OH > PPE-MA > PPE. We also drastically improved the compatibility and adhesion between PPE and PMMA by blending a small amount of PMMA grafted PPE copolymer.

Abstract: Polyethylene (PE) has relatively poor adhesion with polar polymeric materials. In an effort to improve the adhesion between PE and thermoplastic polyurethane (TPU), maleic anhydride (MA), hydroxyl (OH), and secondary amine (NHR) functionalized PEs were blended into nonmodified PE. These functional groups will react with urethane linkages in TPU at the temperature of melt processing. We bonded these PEs to TPU via lamination and coextrusion. To compare the two processes, we determined the interfacial copolymer density Σ considering both advection and interfacial area generation. We found that the development of adhesion in coextrusion was much faster in comparison with lamination at the same temperature. This difference was attributed to the extensional and compressive flow in coextrusion overcoming the diffusion barrier at the interface and forcing reactive species to penetrate the interface. The effects of functional group reactivity and processing variables on adhesion were correlated with interfacial copolymer coverage. Amine functionalized PE showed dramatic adhesion improvement even at 1 wt %. © 2011 American Institute of Chemical Engineers AIChE J, 2011