Fabricating sea-island structure and co-continuous structure in PMMA/ASA and PMMA/CPE blends: Correlation between impact property and phase morphology

Two phase morphologies (i.e., “sea-island structure” and “co-continuous structure”) were obtained in poly(methyl methacrylate) (PMMA)/acrylonitrile-styrene-acrylate copolymer (ASA) (80/20, w/w) blends and PMMA/chlorinated polyethylene (CPE) (80/20, w/w) blends, respectively. An interesting result was that the unnotched Izod impact strengths of PMMA/ASA and PMMA/CPE were approximately the same while the notched Izod impact strength of PMMA/ASA was twice that of PMMA/CPE. In order to explore the causes of this phenomenon, a series of tests were carried out. The phase morphologies were verified by selective extraction test, scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). Double-notch four-point-bending (DN-4PB) tests and the comparison of normal and notched tensile tests demonstrated that the CPE network in PMMA/CPE was notch sensitive and more easily destroyed than ASA particles in PMMA/ASA, hence a toughening mechanism was proposed. Other tests, such as rheological properties, dynamic mechanical thermal analysis (DMTA), SEM of impact-fractured surfaces, tensile and flexural properties, were also conducted. This work might have guiding significance for designing polymer blends with different phase morphologies.