Effect of gamma irradiation on the thermal and mechanical behaviour of polypropylene and polyethylene blends

Preparation of Waste PP/Fly Ash/Waste Stone Powder Composites and Evaluation of Their Mechanical Properties

The research was carried out to analyze the combined and mechanical properties of polypropylene (PP)/fly ash (FA)/waste stone powder (WSP) composite materials. PP, FA and WSP were mixed and prepared into PP100 (pure PP), PP90 (90 wt% PP + 5 wt% FA + 5 wt% WSP), PP80 (80 wt% PP + 10 wt% FA + 10 wt% WSP), PP70 (70 wt% PP + 15 wt% FA + 15 wt% WSP), PP60 (60 wt% PP + 20 wt% FA + 20 wt% WSP) and PP50 (50 wt% PP + 25 wt% FA + 25 wt% WSP) composite materials using an injection molding machine. The research results indicate that all PP/FA/WSP composite materials can be prepared through the injection molding process and there are no cracks or fractures found on the surface of the composite materials. The research results of thermogravimetric analysis are consistent with expectations, indicating that the preparation method of the composite materials in this study is reliable. Although the addition of FA and WSP powder cannot increase the tensile strength, it is very helpful to improve the bending strength and notched impact energy. Especially for notched impact energy, the addition of FA and WSP results in an increase in the notched impact energy of all PP/FA/WSP composite materials by 14.58-22.22%. This study provides a new direction for the reuse of various waste resources. Moreover, based on the excellent bending strength and notched impact energy, the PP/FA/WSP composite materials have great application potential in the composite plastic industry, artificial stone, floor tiles and other industries in the future.

Structural Insights into LDPE/UHMWPE Blends Processed by γ-Irradiation

Ultra-high-molecular-weight polyethylene (UHMWPE) matrices containing low-density polyethylene (LDPE), hydroxyapatite (HAp) as filler, and rosemary extract (RM) as stabilizer were investigated for their qualification for long-term applications. The significant contributions of the blend components were analyzed, and variations in mechanical properties, oxidation strength, thermal behavior, crystallinity, and wettability were discussed. SEM images of microstructural peculiarities completed the introspective survey. The stability improvement due to the presence of both additives was an increase in the total degradation period of 67% in comparison with an unmodified HDPE/UHMWPE blend when the materials were subjected to a 50 kGy γ-dose. There was growth in activation energies from 121 kJ mol^-1 to 139 kJ mol^-1 when HAp and rosemary extract delayed oxidation. The exposure of samples to the action of γ-rays was found to be a proper procedure for accomplishing accelerated oxidative degradation. The presence of rosemary extract and HAp powder significantly increased the thermal and oxidation resistances. The calculation of material lifetimes at various temperatures provided meaningful information on the wearability and integrity of the inspected composites.

Radiation Processing of Styrene-isoprene-styrene/Poly(ε-caprolactone) Blends

The irradiation consequences on styrene-isoprene-styrene (SIS)/poly(ε-caprolactone) (PCL) blends are discussed starting from the oxidation initiation. Three characterization methods: chemiluminescence, differential scanning calorimetry and FTIR spectroscopy are applied. The differences that exist between the two components are revealed, when the oxidation rates of the inspected formulas depend on the blending proportion and the degradation conditions. The relevant activation energies characterizing the oxidation strength as well as the kinetic parameters of degradation during the accelerated damaging of blended polymers are related to the inhibition protection of PCL on the faster oxidation of SIS. The interaction between mixed components is revealed by the structural modifications simultaneously accompanied by the competition of formation and decay of radicals.