Rubber-Modified Glassy Amorphous Polymers Prepared via Chemically Induced Phase Separation. 1. Morphology Development and Mechanical Properties

Abstract

The introduction of rubbery particles can be applied to enhance shear yielding and, consequently, the toughness of brittle amorphous polymers. The critical transition in these polymers from crazing to shear yielding requires a submicrometer-or even nanometer-sized rubbery phase. These can be obtained via coalescence suppression in processes involving chemically induced phase separation but are also obtained in interpenetrating polymer networks (IPN) where cross-linking or gelation is responsible for the morphology control. In all cases, the formation of a nanometer-sized morphology is accompanied by an enhanced interphase mixing, i.e., incomplete demixing resulting in a broad interface in which the composition gradually changes from one phase to the other. In this study, the influence of interphase mixing on the mechanical properties has been investigated. Besides the standard semi-IPN system based on poly(methyl methacrylate) and aliphatic epoxy resins, two additional systems being composed of the same constituents but with an increased degree of interfacial mixing have been investigated: a full-IPN prepared by cross-linking the acrylate phase and a copolymer system in which the acrylate phase is chemically bonded to the epoxy phase. In situ small-angle X-ray scattering experiments during tensile deformation demonstrated that the microscopic deformation mechanism is clearly influenced by the degree of demixing. Despite this, the macroscopic toughness is found to be rather system independent since for all three systems, a comparable synergistic toughening effect is observed in both tensile and impact deformation.

Multi‐Scale Analysis of Mechanical Properties of Amorphous Polymer Systems

“…This was inspired by synchrotron experiments on a similar system, PMMAaliphatic epoxy blends with extremely small structures in the order of 30 nm. [56][57][58][59] Under low speed testing ductile behavior was found since the material was able to initiate voids within the rubbery domain prior to shear yielding. Under high loading rates, realized by notching the sample, the material behaved brittle and no cavitation occurred.…”

Prediction of brittle-to-ductile transitions in polystyrene

“…The incorporation of precavitated, adhering core-shell rubbers, as proposed by Refs. [17,30], could support these ligaments during deformation to transfer more load. As a result they would be able to induce sequential yielding throughout the RVE, increase the material volume participating in the deformation and hence further improve the toughness.…”

“…Experimental results provided by Van der Sanden [28] and Jansen [30] showed that a BDT occurs in non-adhering core-shell rubber filled polystyrene at 55 vol.% inclusions of 200 nm and 35 vol.% inclusions of 80 nm, respectively. In Jansen's example a critical inter-particle distance of 11.5 nm is found.…”

Investigation on thermoplastic co‐poly(ether‐ester) elastomer toughened poly(methylmethacrylate) blends

“…17 PMMA have been toughened successfully by incorporating rubber particles. 18 They achieved superior toughness values with the average particle size of 50 nm in 70:30 PMMA/rubber blend. Blends of PMMA with polyethylene terephthalate (PET) was studied by Kamata et al, 19 and their results shows good processability and high impact strength.…”