Continuous electron-induced reactive processing – A sustainable reactive processing method for polymers

Stability Qualification of Resins/Metallic Oxide Composites for Surface Oxidative Protection

The accelerated degradation of alkyd resins via γ-irradiation is investigated using non-isothermal chemiluminescence. The stability qualification is possible through the comparison of emission intensities on a temperature range starting from 100 °C up to 250 °C under accelerated degradation caused by radiolysis scission. The measurements achieved in the samples of cured state resin modified by various inorganic oxides reveal the influence of metallic traces on the aging amplitude, when the thermal resistance increases as the irradiation dose is augmented. Even though the unirradiated samples present a prominent chemiluminescence intensity peak at 80 °C, the γ-processed specimens show less intense spectra under the pristine materials and the oxidation starts smoothly after 75 °C. The values of activation energies required for oxidative degradation of the sample subjected to 100 kGy are significantly higher in the composite states than in the neat resin. The degradation mechanism of polymerized resins is discussed taking into account the effects of fillers on the stability of studied epoxy resin at various temperatures when the degradation and crosslinking are in competition for the decay of free radical.

Comparison of Shielding Material Dispersion Characteristics and Shielding Efficiency for Manufacturing Medical X-ray Shielding Barriers

During medical diagnoses, X-ray shielding barriers are used to protect against direct and indirect X-rays. Currently, lead is used as the primary material for shielding barriers; however, the demand for eco-friendly shielding barriers has been increasing. Conventionally, shielding barriers are manufactured using a mechanically bonded combination of lead and aluminum; however, in this study, a plastic-based injection-molded product was developed using tungsten as an eco-friendly alternative to lead. A new process technology was required for mixing tungsten-which can be difficult to process-with a polymer. Consequently, the mixing conditions within the injection molding machine and the related compounding technology factors were analyzed. The process technology considered the pre-mixing method using powdery polymer, particle dispersion method, number of screw rotations, and amount of filler input. The product's shielding performance was then analyzed. The tungsten content of the 2-mm thick barrier manufactured using the proposed method was 90 wt%, and the lead equivalent was 0.321 mmPb. To increase the effectiveness of injection molding in the manufacturing process, specific hourly compounding conditions were proposed. Consequently, the process technology method developed in this study can be considered suitable for manufacturing various shielding barriers.