Structure-Property Relationships in Polymeric Materials Generated by Electron Beam Processing

Abstract

The work presented in this dissertation is in the subject area of radiation chemistry of polymeric materials and begins with a literature review of that subject. Along with the general literature review, three smaller and more specific reviews are presented for background information relevant to the three systematic studies addressed in the authors research. Following the literature review, these three studies involving the electron beam processing and subsequent characterization of various polymeric materials are presented.

The first study involves the generation of cellular materials by electron beam irradiation. A technique was developed for generating a cellular structure in a radiation curable composition prior to irradiation, extruding the composition, and then curing the froth in the electron beam accelerator, thus locking into place the cellular structure. A systematic study of different monomer/oligomer systems was conducted with mono-, di-, and triacrylate model systems utilized for comparative purposes.

The second study is a follow up investigation of previous work in the area of physical aging of polymers. A unique phenomena was discovered in which a physically aged polymer displaying a typical excess enthalpic aging peak by DSC was observed to deage when exposed to electron beam irradiation. The goal of the presented work was to investigate what, if any, volumetric changes were occurring in these materials and to further explain the observed phenomena.

The third study involves the irradiation of high density polyethylene films having simple and well-defined stacked lamellar morphology without a distinct presence of row-nucleated fibril structures. These materials have been utilized to carry out investigations into the effects of radiation on their solid state structure-property relationships. These materials were characterized (as a function of radiation dose) with respect to the following areas with the utilized characterization technique(s) following: tensile behavior (Instron), dynamic mechanical behavior (DMS), melting behavior (DSC), lamella thickness (SAXS, TEM, and HSEM), orientation (WAXS) and microporous membrane formation (HSEM).