Doice Moyo | Nelson Mandela Metropolitan University (original) (raw)

Papers by Doice Moyo

Handbook of Food Powders, 2013

Plants, Feb 13, 2024

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

APPlicATioNs Nonwovens can be engineered for numerous applications in a number of different areas... more APPlicATioNs Nonwovens can be engineered for numerous applications in a number of different areas with new applications continuously being found. some of these include geotextiles, building, thermal and sound insulation materials, hygienic products, health-care, automotive industries, agriculture, construction, and household amongst others 2 . MANuf AcTuriNg NoNwoveNs The production of nonwoven fabrics follows a much shorter route or process from raw material to finished products compared to apparel fabric production through weaving and knitting. The short route of production is the main attraction of this sector because of the high production speeds employed, higher profit margins and the general versatility of the production process. The process involves initially laying loose fibres into a web which is then consolidated by any of the several methods available namely chemical, spunbonding, thermal, needlepunching and/or hydroentanglement 3 . HydroeNTANgleMeNT Hydroentanglement is a common mechanical method of bonding fibres together to form a nonwoven fabric. This process employs collimated high pressure water jets issued from a series of parallel jet-heads (manifolds) for entangling the fibre-web which is carried on a perforated belt producing a fibrous structure of high integrity. The high pressure waterjets impinging on fibres are the sources of energy for twisting and entangling them in a complex process of displacement and rearrangement which eventually forms a fabric from a cohesive network of fibrous assembly 3,4 . The hydroentanglement process is depicted in Figures 1 and 2.

CRC Press eBooks, Aug 8, 2019

Elsevier eBooks, 2013

Abstract: This chapter deals with process control in the field of nonwoven manufacturing. A brief... more Abstract: This chapter deals with process control in the field of nonwoven manufacturing. A brief background about different nonwoven manufacturing processes is provided. Different manufacturing processes such as needle punching, hydroentanglement, melt blowing and spunbonding are discussed. Roles of different processing parameters and their influence on the final product are covered. Various ways to control the processing parameters are discussed. Some future directions are also highlighted.

Textile Research Journal, Jan 16, 2014

The hydroentanglement process is highly energy intensive compared to other methods of manufacturi... more The hydroentanglement process is highly energy intensive compared to other methods of manufacturing nonwoven fabrics. This paper presents an exploratory study on optimizing the usage of hydroentanglement energy so as to lower the processing cost. The experiments were based on a Box–Behnken experimental design (BBD) and multivariate linear regression analysis to model the tensile strength as response to variables. Three variables were selected, namely fabric area weight (150–400 g/m2), machine speed (5–15 m/min) and waterjet pressure (40–200 bars). These parameters were employed in two sets of experiments to achieve maximum tensile strength of viscose nonwoven fabrics. The first experiment was conducted using higher waterjet pressures of 100, 150 and 200 bars, which were proved to have exceeded the optimum levels. The second experiment was conducted at relatively lower waterjet pressures of 40, 60 and 80 bars. The results on tensile strength were analyzed using the SYSTAT 10 software package and response surface plots were prepared. The linear, quadratic and interactive effects of the main variables were shown to be significant. Interactions amongst the variables were found to have either a synergistic (positive) or offsetting (negative) relationship with the fabric tensile strength. The interactions involving machine speed were predominantly offsetting. The 400 g/m2 area weight fabric produced at 80 bars of waterjet pressure achieved a fabric tensile strength of 222 cN, which compared favorably with that of 232 cN obtained at 200 bars of waterjet pressure. In this exploratory study using BBD, linear, quadratic and interactive effects were observed to be significant and the usage of hydroentanglement energy was successfully optimized. This indicates the possibility of achieving high fabric strength but at lower waterjet pressures; in other words, by employing low hydroentanglement energy and thereby minimizing the processing cost.

Textile Research Journal, Jul 21, 2016

The mechanics of nonwoven fabrics is largely dependent on fiber properties, and other physical fa... more The mechanics of nonwoven fabrics is largely dependent on fiber properties, and other physical factors such as structural arrangement and degree of entanglement of the fibers. In this study, modeled and experimental stress–strain behaviors of uniaxially loaded hydroentangled nonwoven fabrics have been analyzed and compared. The theoretical values from the model were deduced from the measured properties of micro-samples, namely, fiber volume faction, orientation distribution and mechanical properties. Testing of the micro-samples was performed on a Deben Microtest Module fitted in the FEI Quanta 200 Scanning Electron Microscope. The experimental stress–strain results show that the structure is in the linear region when the modeled results approach the highest specific stress. Also, the theoretical models highly overestimate the specific stress of the hydroentangled nonwoven fabrics. The results show that the application of the model was limited in predicting tensile stress. Furthermore, a trapezoid method was used to quantify the actual deformation energy from the stress–strain graphs up to the ultimate tensile strength. The theoretical deformation energy was estimated and compared to the experimental values. The model was subsequently modified to improve its predictive capability.

Journal of Industrial Textiles, Dec 30, 2013

A soy protein-based water-soluble binder composition for natural fiber nonwoven fabric is discuss... more A soy protein-based water-soluble binder composition for natural fiber nonwoven fabric is discussed in this paper. Before applying to viscose fibers, foam decay studies of soy protein and acrylic binders are carried out and results are compared. The bio-binder (soy protein and sodium dodecyl sulphate modified soy protein) composition effectively binds natural fibers in a nonwoven fabric by foam application method. Such fabrics are widely used for industrial wipes and non-reusable products such as diapers, sanitary napkins, bandages, etc. The mechanical and thermal properties of viscose fabric bonded with soy protein bio-binder are compared with the same fabric produced with commercially applied acrylic binder. Scanning electron microscope was used to confirm the bonding of the viscose fiber with the bio-binders.

The hydroentanglement of fibres is achieved by the energy of the high-velocity waterjets. This me... more The hydroentanglement of fibres is achieved by the energy of the high-velocity waterjets. This method is highly energy intensive and costly, hence the attempt to study the energy transfer during the process. Generally, the amount of energy used, and the resultant degree of fibre entanglement, determines the tensile strength of the nonwoven fabric as a consequence of the inter-fibre friction. Here, the relationship between hydroentangling energy from the waterjets and the changes it brings about in the nonwoven fabric strength were studied. In the study, the energies of the waterjets transferred to every fabric sample as a function of the waterjet pressure, machine speed, machine efficiency and the web area weight were quantified, and the resultant fabric tensile strengths were compared. The nonwovens were produced from viscose and PLA fibres using different energy profiles; the objective being to identify the most energy-efficient. The light PLA nonwoven fabrics, which were less than 150 g/m 2 , showed a relatively higher change in the cross-machine direction strength than the corresponding viscose nonwoven fabrics.

Plants

Medicinal plants are the product of natural drug discoveries and have gained traction due to thei... more Medicinal plants are the product of natural drug discoveries and have gained traction due to their pharmacological activities. Pathogens are everywhere, and they thrive in ideal conditions depending on the nutrients, moisture, temperature, and pH that increase the growth of harmful pathogens on surfaces and textiles. Thus, antimicrobial agents and finishes may be the solution to the destruction of pathogens. This review article presents an analysis of various aspects of producing antimicrobial finishings, the microorganisms, their mechanism of attachment to natural and synthetic fibre, the effect of microbial growth, and the principle and mechanism of the microbial activity of the medicinal plants. Furthermore, the extraction methods, qualitative and quantitative phytochemical evaluations of antimicrobial efficacy, and developments of antimicrobial treated textiles using various agents are covered in this review.

Nelson Mandela Metropolitan University, 2012

Fibres to Smart Textiles, 2019

Textile Research Journal, 2016

Journal of Industrial Textiles, 2013

Textile Research Journal, 2014

Journal of Biobased Materials and Bioenergy, 2012

Journal of Industrial Textiles, 2007

Hydroentanglement is a versatile and relatively little explored method of bonding the fibrous web... more Hydroentanglement is a versatile and relatively little explored method of bonding the fibrous web using high-pressure water jets. These nonwoven structures have an extensive range of applications–for example, wipes, carpet backing, filters, sanitary, medical dressings, and composites. Such applications require certain functional characteristics in hydroentangled structures, besides basic properties, which are required to be engineered by judicious optimization of the hydroentanglement process. In this study, a number of hydroentangled structures have been produced based on Taguchi's experimental design technique by varying the process parameters: namely, feed rate and water jet pressures. The simultaneous effect of more than one parameter has been investigated on the dimensional and mechanical properties of hydroentangled fabrics. These process parameters are then empirically related with the fabric properties using the multiple regression technique. The influence of jet pressur...

The textile industry generates a significant amount of waste within the entire value chain includ... more The textile industry generates a significant amount of waste within the entire value chain including the consumers. With the advent of powerful environmental activists and a general consciousness of the need to sustain the resources available, there has been a shift toward reassessing activities that would lead to reduced damage of the environment. Packaging is an important element of the industry providing protection, handling, marketing promotion, and other functions. The common packaging materials used in the industry are plastics and paper-based. However, textile packaging contributes a significant amount of solid waste that damages the environment. The industry has responded in different ways to reduce the waste generation by promoting recycling, reuse, energy recovery, minimization, and using novel compostable polymers. This management of packaging waste is being adopted by large retailers and brands in their effort to promote sustainability.

Textile Research Journal, 2013

In the hydroentanglement process, high velocity multiple waterjets are generated through the nozz... more In the hydroentanglement process, high velocity multiple waterjets are generated through the nozzles before impinging on the hydroentangling belt or fibre-web and exert an impact force. In this study, a technique to measure important characteristics of the waterjets, namely, the coefficient of velocity, Cv, and coefficient of discharge, Cd, is proposed. The technique offers a simple and practical method to determine the energy transfer efficiency from the manifold to the waterjets. The measured Cv and Cd values were observed to decrease with an increase in waterjet pressure, which implied higher energy losses at higher waterjet pressures. These results were then used in the next experiment to measure the waterjet impact force. The waterjet impact force was measured using a Tensiometer-R2000 fixed on a vibration-free stand at different waterjet pressures, varied from 30 to 120 bar. It was observed that the waterjet impact forces were equal across the width of the machine at a given p...