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The purpose of this study is to numerically examine the heat transfer and transport of space charges in the solid insulating materials [low density polyethylene (LDPE), flame retardant type 4 (FR4), Polytetrafluoroethylene (PTFE)] using the transmission line modeling (TLM) method. Besides, a comprehensive study is performed on the mutual influences of heat transfer and space charges transport within the solid dielectric bulk.

The obtained governing equations including continuity and circuit equations are coupled with heat transfer equations, and they are solved via fourth-order Runge–Kutta method.

The electric potential and field, current density and temperature distribution are calculated. It is shown that compared with FR4 and PTFE, the temperature increment rate in LDPE is much lower. Moreover, the heat transfer in the solid insulating materials bulk increases the homo-charges density and temperature in the vicinity of electrodes. Hence, the reduction in electric field is reflected in the potential deformations in the proximity of electrodes. Furthermore, where the electric field is maximized, the temperature is minimized.

This study is restricted to two-dimensional problems.

Interestingly, because of the lower temperature in LDPE, the current density and their increment rates in LDPE are much lower than that in FR4 and PTFE dielectric materials.

Purpose – This work aims to study the treatment of adsorbant on the increasing liquid hydrocarbon quality produced by pyrolysis low density polyethylene (LDPE) plastic waste at low temperature. The hydrocarbon distribution, physicochemical properties and emission test were also studied due to its application in internal combustion engine. This research uses pure Calcium carbonate (CaCO₃) and pure activated carbon as adsorbant, LDPE type clear plastic samples with control variable that is solar gas station.

Design/Methodology/Approach – LDPE plastic waste of 10 kg were vaporized in the thermal cracking batch reactor using LPG 12 kg as fuel at range temperature from 100 to 300°C and condensed into liquid hydrocarbon. Furthermore, this product was treated with the mixed CaCO₃ and activated carbon as adsorbants to decrease contaminant material.

Findings – GC-MS identified the presence of carbon chain in the range of C6–C44 with 24.24% of hydrocarbon compounds in the liquid. They are similar to diesel (C6–C14). The 30% of liquid yields were found at operating temperature of 300°C. The calorific value of liquid was 46.021 MJ/Kg. This value was 5.07% higher than diesel as control.

Originality/Value – Hydrocarbon compounds in liquid produced by thermal cracking at a low temperature was similar to liquid from a catalytic process.

The aim of this paper is to evaluate the storage stability of improved dambu, a steamed granulated dumpling product generally made from millet, was produced from maize (Zea mays), millet (Pennisetum glaucum), sorghum (Sorghum bicolor) and acha (Digitaria exilis). It is a popular mid‐day meal of the Fulanis of Nigeria normally sprinkled into fermented skimmed milk or whole milk and sugar may be added to taste.

Improved dambu was prepared in the laboratory using decorticated clean cereal grains which were pulverished into coarse particles, mixed with spices, preservative (sorbic acid) and water and steamed for 20 min. The improved dambu products were packaged in low‐density polyethylene (LDPE), LDPE with plastic and LDPE with paperboard and stored at room temperature (25 ^○C) for six days. Analysis was carried out on the products following documented and established procedures.

Data obtained indicated that during storage, pH decrease was observed while titratable acidity increased for improved dambu products. The microbial load (cfu/g) increased with storage time for all the products packaged in LDPE, LDPE with plastic and LDPE with paperboard. Dambu has a limited storage life of one day at room temperature (25 ^○C) and four days with 0.2 per cent (w/w) sorbic acid as preservative. Micro‐organisms of significance in the products are Aspergillus sp, Penicillum sp, Candida sp, Staphylococcus aureus and Enterobacter aerogenes. The nature of the microflora suggested that dambu is a good substrate for fungal growth. In the comparative study of dambu products with and without sorbic acid, there was no significant difference in the mean scores for all the assessed parameters.

The consumption of dambu from different cereal grains is encouraged especially where a particular cereal is off season. The shelf‐life of dambu was extended to four days by using 0.2 per cent (w/w) sorbic acid as preservative and packaged in LDPE with plastic and LDPE with paperboard. Further research should be carried out to extend the shelf‐life more.

The findings have suggested that dambu is necessary to cereal industry and baby foods (weaning foods).

The results of this research contributes to the knowledge of cereal meals, especially those that are indigenous to Nigeria and West Africa.

To develop a method for the preparation of multi‐walled carbon nanotube reinforced low density polyethylene (LDPE) composites (MWNTs/LDPE), based on ultrasonic vibration, solution casting and melt mixing.

The preparation for MWNTs/LDPE composites was carried out by vibration of carbon nanotubes (CNT), solution casting and melt mixing for MWNTs and LDPE. The physical chemical properties of the composites were characterised using a variety of techniques including scanning electron microscopy, resistance and tensile measurement.

It was found that the preparation method reported had significantly improved the dispersion of multi‐walled carbon nanotubes (MWNTs) in LDPE matrix, resulting in the improvement of tensile strength of the composite. The percolation of MWNTs in LDPE matrix was between 10 and 15 wt% (10¹⁶‐10⁸ Ω cm).

The preparation method reported addressed a problem concerning the dispersion of CNT in polymer matrix. The method developed provided a practical and effective solution to such a problem.

The preparation method for MWNTs/LDPE composites involving vibration of CNT, solution casting and melt mixing for MWNTs and LDPE was novel. The method could be adapted for use in industrial scale.

The purpose of this paper is to optimize and improve a bipolar charge transport (BCT) model used to simulate charge dynamics in insulating polymer materials, specifically low-density polyethylene (LDPE).

An optimization algorithm is applied to optimize the BCT model by comparing the model outputs with experimental data obtained using two kinds of measurements: space charge distribution using the pulsed electroacoustic (PEA) method and current measurements in nonstationary conditions.

The study provides an optimal set of parameters that offers a good correlation between model outputs and several experiments conducted under varying applied fields. The study evaluates the quantity of charges remaining inside the dielectric even after 24 h of short circuit. Moreover, the effects of increasing the electric field on charge trapping and detrapping rates are addressed.

This study only examined experiments with different applied electric fields, and thus the obtained parameters may not suit the experimental outputs if the experimental temperature varies. Further improvement may be achieved by introducing additional experiments or another source of measurements.

This work provides a unique set of optimal parameters that best match both current and charge density measurements for a BCT model in LDPE and demonstrates the use of trust region reflective algorithm for parameter optimization. The study also attempts to evaluate the equations used to describe charge trapping and detrapping phenomena, providing a deeper understanding of the physics behind the model.

This study aims to develop a biodegradable linear low-density polyethylene (LLDPE)/starch blends with improved mechanical and flow characteristics and evaluate the probability of using essential oils such as Moringa oleifira and castor oils as green plasticizers and compatibilizers to avoid using harmful chemicals.

Corn starch was blended with LLDPE through the melt blending technique. The corn starch content was varied from 5 to 40 phr in LLDPE. To enhance poor mechanical characteristic of the LLDPE/starch, essential oils such as M. oleifira and castor oils were incorporated into the composites with different concentrations starting from 1 to 7 phr. The essential oils’ effect on mechanical, flow character, thermal stability and electrical properties of the LLDPE/starch was also investigated. The morphology of LLDPE/starch containing essential oils was also investigated by scanning electron microscope (SEM).

The results revealed that increasing the corn starch content had an adverse effect on mechanical and flow characteristics of the composites, whereas incorporation of essential oils had increased the flow and mechanical characteristics of the composites. Also, dielectric measurements revealed that permittivity and dielectric loss increased by increasing oil content. Moreover, the values of the blends containing castor oil are higher compared to that containing M. oleifira. The SEM micrographs illustrated that the presence of essential oils in LLDPE/starch enhanced the distribution and the homogeneity of the composites, and the particle size of starch granules became smaller in LLDPE matrix.

This study aims to introduce green plasticizer and compatibilizer to avoid using harmful chemicals in packaging industry.

The purpose of this paper is to study a new method with which multi‐walled carbon nanotubes (MWNTs) can be dispersed and aligned in low density polyethylene (LDPE) for improving its mechanical properties.

Dispersion and alignment of MWNTs in LDPE matrix are enhanced by ultrasonic vibration, solution casting and melt mixing and flow moulding method. The properties of the composite are characterised using scanning electron microscopy, tensile testing machine and the Izod impact testing machine.

It is found that MWNTs in LDPE achieve some dispersion and alignment resulting in improvement in LDPE's strength and toughness.

Polymer/CNTs nanocomposites are expected to have good process ability of the polymers and high mechanical and functional properties of the CNTs. Enhancing dispersion and alignment of MWNTs in the polymer matrix will promote and expand the applications and development of polymer/MWNTs nanocomposites.

The method that enhances MWNTs dispersion and alignment in LDPE matrix provides a new way for alignment of other CNTs in polymer matrix.

This paper aims to perform an experimental investigation on the impact strength, compressive strength, tensile strength and flexural strength of fly ash-based green composites and to compare with these polyvinyl chloride (PVC), high density polyethylene (HDPE) and low density polyethylene (LDPE).

Fly ash-based polymer matrix composites (FA-PMCs) were fabricated using hand layup method. Composites containing 100 g by weight fly ash particles, 100 g by weight brick dust particles and 50 g by weight chopped glass fiber particles were processed. Impact strength, compressive strength, tensile strength and flexural strength of composites have been measured and compared with PVC, HDPE and LDPE. Impact strength of the FA-PMC is higher than that of PVC, HDPE and LDPE. Structural analysis of pipes, gears and axial flow blade was verified using ANSYS. Barlou’s condition for pipes, Lewis–Buckingham approach for gears and case-based analysis for axial flow blades were carried out and verified.

Pipes, gears and axial flow blades made form fly ash-based composites were found to exhibit improved thermal resistance (i.e. better temperature independence for mechanical operations), higher impact strength and longer life compared to those made from PVC, HDPE and LDPE. Moreover, the eco-friendly nature of the raw materials used for fabricating the composite brings into its quiver a new dimension of appeal.

Experimental investigation on the impact strength, compressive strength, tensile strength and flexural strength of fly ash-based green composites has not been attempted yet.

The objective of this research is to investigate the effects of copper oxide on the rheological properties of low density polyethylene (LDPE) such as viscosity, storage and loss modulus, phase angles, complex viscosity on the concentration of copper oxide and temperature. It was found that the addition of copper oxide to LDPE at a fix temperature did not affect the dynamic properties significantly. However, the copper oxide and temperature has particularly reduced the viscosity of the molten compound.

The purpose of this study is to develop a multifunctional coating layer based on nitrocellulose (NC)/acrylic resins containing precipitated silica and kaolin and investigate its suitability for use in packaging applications.

Different loading levels (1 and 5 Wt.%) of precipitated silica or kaolin particles were incorporated into NC/acrylic-based coating formulations and applied on low-density polyethylene (LDPE) films. The coatings and coated LDPE films were characterized in terms of structural, physical, mechanical, thermal, optical, surface, morphological and water vapor barrier properties.

The glossiness of the coating formulations decreased by increasing the precipitated silica and kaolin content. The incorporation of kaolin (1 and 5 Wt.%) and precipitated silica (1 Wt.%) had no significant effect on the melting temperature of LDPE film; however, with the addition of 5 Wt.% precipitated silica, the melting and crystallization temperatures were significantly changed. The incorporation of 5 Wt.% precipitated silica and kaolin also enhanced the water vapor barrier properties of LDPE films. The light transmittance declined with the precipitated silica and kaolin addition, especially in the ultraviolet (UV)-A/UV-B spectrum regions indicating an excellent UV light protection.

It was concluded that NC/acrylic resins coatings containing precipitated silica and kaolin exhibit improved thermal stability, UV and water vapor barrier properties and have the potential for use in packaging applications.