Mechanical, electrical, and thermal properties of irradiated low-density polyethylene by electron beam

Electron beam technology for Re-processing of personal protective equipment

Beginning with the outbreak of COVID-19 at the dawn of 2020, the continuing spread of the pandemic has challenged the healthcare market and the supply chain of Personal Protective Equipment (PPE) around the world. Moreover, the emergence of the variants of COVID-19 occurring in waves threatens the sufficient supply of PPE. Among the various types of PPE, N95 Respirators, surgical masks, and medical gowns are the most consumed and thus have a high potential for a serious shortage during such emergencies. Considering the unanticipated demand for PPE during a pandemic, re-processing of used PPE is one approach to continue to protect the health of first responders and healthcare personnel. This paper evaluates the viability and efficacy of using FDA-approved electron beam (eBeam) sterilization technology (ISO 11137) to re-process used PPE. PPEs including 3M N95 Respirators, Proxima Sirus gowns, and face shields were eBeam irradiated in different media (air, argon) over a dose range of 0-200 kGy. Several tests were then performed to examine surface properties, mechanical properties, functionality performance, discoloration phenomenon, and liquid barrier performance. The results show a reduction of filtration efficiency to about 63.6% in the N95 Respirator; however, charge regeneration may improve the re-processed efficiency. Additionally, mechanical degradation was observed in Proxima Sirus gown with increasing dose up to 100 kGy. However, no mechanical degradation was observed in the face shields after 10 times donning and doffing. Apart from the face shield, N95 Respirators and Proxima Sirus gown both show significant mechanical degradation with ebeam dose over sterilization doses (>25 kGy), indicating that eBeam technology is not appropriate for the re-processing these PPEs.

Functionalized allylamine polyphosphate as a novel multifunctional highly efficient fire retardant for polypropylene

In this study, an efficient novel allylamine polyphosphate (AAPP) as a flame retardant (FR) crosslinker is used to improve the thermal stability of flame retarded polypropylene (PP) composites under electron beam treatment.

Electronic Characterization of Au/DNA/ITO Metal-Semiconductor-Metal Diode and Its Application as a Radiation Sensor

Deoxyribonucleic acid or DNA molecules expressed as double-stranded (DSS) negatively charged polymer plays a significant role in electronic states of metal/silicon semiconductor structures. Electrical parameters of an Au/DNA/ITO device prepared using self-assembly method was studied by using current–voltage (I-V) characteristic measurements under alpha bombardment at room temperature. The results were analyzed using conventional thermionic emission model, Cheung and Cheung’s method and Norde’s technique to estimate the barrier height, ideality factor, series resistance and Richardson constant of the Au/DNA/ITO structure. Besides demonstrating a strongly rectifying (diode) characteristic, it was also observed that orderly fluctuations occur in various electrical parameters of the Schottky structure. Increasing alpha radiation effectively influences the series resistance, while the barrier height, ideality factor and interface state density parameters respond linearly. Barrier height determined from I–V measurements were calculated at 0.7284 eV for non-radiated, increasing to about 0.7883 eV in 0.036 Gy showing an increase for all doses. We also demonstrate the hypersensitivity phenomena effect by studying the relationship between the series resistance for the three methods, the ideality factor and low-dose radiation. Based on the results, sensitive alpha particle detectors can be realized using Au/DNA/ITO Schottky junction sensor.

The Effect of TMPTMA Addition on Electron-beam Irradiated LDPE, EVA and Blend Properties

In this work low density polyethylene (LDPE) and ethylene vinyl acetate (EVA) were blended in the presence of trimethylol propane trimethylacrylate (TMPTMA) (0 to 6 phr). The resultant blends were irradiated with a 3 MeV electron-beam resulting in dosages of 0 to 240 kGy using a rhodotron accelerator system. The effect of radiation exposure on the LDPE/EVA/TMPTMA blend properties were investigated with respect to gel content, tensile strength and elongation up to breakage of the blends. The findings indicate that increasing EVA and TMPTMA content yield tighter network structures through enhanced blend crosslinking, which is a direct consequence of irradiation. For pure EVA significant tensile strength improvements are evident as irradiation increases up to 210 kGy. Irradiated blends exhibit improved tensile strength and elongation at breakage with respect to pure LDPE and EVA. Volume resistivity (VR) and dielectric constant (DC) of the blends were also studied as a function of EVA content, TMPTMA content and radiation dosage. Increasing EVA and TMPTMA content enhances DC and VR values, whereas, increasing irradiation dosage only effects VR values of the blends. The maximum VR value attained in this work corresponds to a radiation dosage of 170 kGy and a blend comprising of 30 wt% of EVA.