The glass transition temperatures (Tg's) of ultrathin films (thickness 80-18 nm) of polystyrene (PS) and poly(methyl methacrylate) (PMMA) were measured on surfaces with interfacial energies (γSL) ranging from 0.50 to 6.48 mJ/m 2 . The surfaces consisted of self-assembled films of octadecyltrichlorosilane (OTS) that were exposed to X-rays in the presence of air. Exposure to X-ray radiation systematically modified the OTS by incorporating oxygen-containing groups on the surface. The interfacial energy for PS and PMMA on the OTS surface was quantified as a function of X-ray dose using the Fowkes-van Oss-Chaudhury-Good model of surface tension. The T g values of the films were characterized by three complementary techniques: local thermal analysis, ellipsometry, and X-ray reflectivity. Within the resolution of the techniques, the results were in agreement. At low values of γSL, the Tg values of PS and PMMA films were below the respective bulk values of the polymers. At high values of γSL, the Tg values of PS and PMMA films were higher than the bulk values and increased monotonically with increasing γSL. The deviation of the Tg values of the films compared to the bulk values increased with decreasing film thickness. For a specific film thickness of PS and PMMA, the difference between the Tg of the film and Tg of the bulk polymer (∆Tg ) Tg film -Tg bulk ) scaled linearly with γSL irrespective of the chemistry of the polymer.

The mechanical properties of blends of high‐density polyethylene (HDPE) with a recycled thermosetting filler, urea‐formaldehyde grit (UFG), were evaluated in the range of 0–23% of filler by volume. Ethylene‐acrylic acid (EAA) copolymers and an ionomer based on EAA were evaluated as compatibilizers. The observed tensile modulus of the ionomer‐treated blends was raised to three times the modulus of virgin polyethylene, whereas the modulus of the untreated blends reached double that of polyethylene. The ionomer‐treated blends also showed a higher tensile strength than the blends without filler treatment. The improvement in the properties was assigned to an increased interaction between the filler and the polymer matrix. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 3220–3227, 2000

The recycling of power transmission cable insulated with crosslinked PE (XLPE) was investigated by using different methods of separation and reprocessing. Separation was attempted by thermo‐chemical, thermo‐mechanical and microwave‐mechanical means, the latter being the most successful. A mechanism encompassing all of these was formulated. Compression molding, extrusion, and injection molding with and without preheating of the material were also investigated. It was found that by preheating the XLPE and injection molding under high injection pressure, the neat XLPE could be formed into shapes with tensile strengths equal to that of the original insulation. In view of available observations, possible mechanisms for the flow and reconsolidation of XLPE crumb are proposed and discussed.