Study on bonding ability of melt-spun polypropylene/polyethylene blend fibers

This article investigates melt spinning of polypropylene (PP) with high-density polyethylene (HDPE) and linear low-density polyethylene (LLDPE) blend fibers at different compositions, as well as the effects of HDPE and LLDPE on the bonding ability of blend fibers in thermal bonding process at different temperatures have been studied. HDPE and LLDPE were added to PP at 3, 5, 7, and 10 wt% to measure the upper threshold of such blends. While HDPE was added up to 7 wt%, PP/LLDPE blend fibers were only spun up to 3 wt% of LLDPE. Differential scanning calorimetry (DSC) revealed that increasing both HDPE and LLDPE contents lead to higher crystallinity values due to polyethylenes nucleating effect on PP. By adding HDPE and LLDPE, the tensile strength of blend fibers before and after bonding was decreased drastically compared to pure PP fibers. On the other hand, the addition of HDPE to PP and increasing bonding temperature enhanced bonding strength.

The Role of Silicon-Based Nanofillers and Polymer Crystallization on the Breakdown Behaviors of Polyethylene Blend Nanocomposites

Good breakdown strength is an important feature for the selection of dielectric materials, especially in high-voltage engineering. Although nanocomposites have been shown to possess many promising dielectric properties, the breakdown strength of nanocomposites is often found to be negatively affected. Recently, imposing nonisothermal crystallization processes on polyethylene blends has been demonstrated to be favorable for breakdown strength improvements of dielectric materials. In an attempt to increase nanocomposites’ voltage rating, this work reports on the effects of nonisothermal crystallization (fast, moderate and slow crystallizations) on the structure and dielectric properties of a polyethylene blend (PE) composed of 80% low density polyethylene and 20% high density polyethylene, added with silicon dioxide (SiO2) and silicon nitride (Si3N4) nanofillers. Through breakdown testing, the breakdown performance of Si3N4-based nanocomposites was better than SiO2-based nanocomposites. Since nanofiller dispersion within both nanocomposite systems was comparable, the enhanced breakdown performance of Si3N4-based nanocomposites is attributed to the surface chemistry of Si3N4 containing less hydroxyl groups than SiO2. Furthermore, the breakdown strength of SiO2-based nanocomposites and Si3N4-based nanocomposites improved, with the DC breakdown strength increasing by at least 12% when both the nanocomposites were subjected to moderate crystallization rather than fast and slow crystallizations. This is attributed to changes in the underlying molecular conformation of PE in addition to water-related effects. These results suggest that apart from changes in the nanofiller surface chemistry, changes in the underlying molecular conformation of polymers are also important to improve the breakdown performance of nanocomposites.

Enhancing the physico-mechanical properties of irradiated rubber/waste plastic blend via incorporation of different fillers for industrial applications

The effect of gamma radiation on the physico-mechanical properties of ethylene propylene diene monomer rubber/styrene butadiene rubber/waste high density polyethylene blend EPDM/SBR/wHDPE (50/50/30) blend reinforced with different types of fillers 10 phr (part per 100 part of rubber, by weight) of HAF-carbon black, Hisil, and prepared modified organo-montmorillonite (OMMT) clay was investigated. The results obtained showed that the organo-montmorillonite (OMMT) clay is the most effective filler for enhancing the physico-mechanical properties of EPDM/SBR/wHDPE vulcanized composites. Scanning electron microscopy and thermogravimetric analysis characteristics were also, studied.