Mohd Rozi Ahmad

Puncture resistance of natural rubber latex unidirectional coated fabrics

A study was conducted on the puncture resistance of high-strength nonwoven natural rubber latex (NRL)-coated fabrics. High strength unidirectional (UD) polyethylene fabrics were coated using single dipping (SD), double dipping (DD), and triple dipping (TD) methods. The puncture resistance of the uncoated and coated fabrics was determined by measuring the force needed to penetrate the fabrics using a blunt probe. The mechanisms and modes of deformation involved during penetration were observed as well. In comparison with the uncoated fabrics, the SD, DD, and TD NRL coated fabrics gave higher puncture resistance of 39%, 47%, and 62%, respectively. The increments of the penetration force were proportional with the increase in the NRL-coated fabric thickness. For the uncoated fabric, the force given by the probe resulted in yarns stretching and yarn slippage upon penetration. However, the NRL-coated fabrics were not severely damaged but resulted in a curvature formed at the frontface of the fabric with minimal backface deformation. From the observations, the modes of failure were similar among the NRL-coated fabrics, that is, fiber stretching, delamination of NRL layer, and stretch marks on the fabric surface. The NRL layer acted as a protective sheath and increases the energy absorption and elasticity characteristics of the UD fabric.

Effects of metal filament’s alignment on tensile and electrical properties of conductive hybrid cover yarns

AbstractOf late, a significant amount of research has been carried out using metals for conductive fabrics and composites to obtain the desired level of electromagnetic shielding along with physical and mechanical properties for its durability. However, incorporating these metallic filaments as core or as an integral part of core deteriorate the mechanical properties of textile yarns and ultimately the fabrics’. Moreover, the transparency of fabrics to high frequency/smaller wavelength waves further increases with the attempt to increase the metallic filament diameter. This study, therefore analyses the effects of metallic filament alignment in order to improve the mechanical properties of the resultant hybrid yarns, and devises an alternative method to increase the amount of conductive filament without increasing the diameter of the conducting wire in hybrid yarn structures. The results suggest that the tensile properties of the proposed hybrid cover yarns with conductive filament as covering component is superior as compared to the yarns having a conductive filament in the core, however, the electrical resistance increases with an increase in conductive filament length. The tenacity, elongation and initial modulus values were enhanced several times by incorporating the conductive filament as spiral covering. Moreover, with the proposed alignment method, the amount of copper in hybrid yarn can be increased up to some extent by changing the number of turns of covering component.

Characteristics of Electrospun PVA-Aloe vera Nanofibres Produced via Electrospinning

The aim of this work was to investigate the characteristics of polyvinyl alcohol (PVA) nanofibres with the incorporation of Aloe vera as a novel polymer-drug carrier. The nanofibres were produced via the electrospinning technique. The morphological structure and properties were characterized using field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). The FESEM image shows homogenous and linear fibre when PVA is mixed with Aloe vera. The average size was 123 nm, smaller than the PVA nanofibre. The presence of aloin in DSC showed that the Aloe vera was successfully embedded within the PVA nanofibre.

Fastness properties and colorimetric characteristics of low temperature dyeing of natural dyes from the barks of Ixonanthes icosandra Jack on polyester fabric

This paper reports on low temperature dyeing of polyester fabrics of natural dye extracts from the barks of Ixonanthes icosandra Jack. The barks were extracted using Boiling Water and Solvent (Methanol) Extraction methods. The dyeing process was conducted using exhaustion method at 85°C for 60 minutes. Three types of mordant were used by metacrome or simultaneous addition of mordant and dye in the dyebath. The dyed samples were measured using spectrophotometer to analyse the shades obtained with regards to L*a*b* values and K/S values (colour strength). The samples were also compared in terms of their ability to withstand washing, perspiration, rubbing/crocking and light. The results showed that dyed fabrics from the solvent extraction method gave higher K/S values in comparison with the dyed fabrics from the boiling water extraction method. The fastness properties of the dyed samples ranged from moderate to good rating except for lightfastness which gave poor rating.

Quasi-static puncture resistance of unidirectional coated fabric

High strength nonwoven fabric in the form of unidirectional structure are being used in ballistic protection applications due to their light weight and flexibility. In this study, natural rubber latex (NRL) was used as a coating material on unidirectional fabrics. It was found that the mechanical properties of the NRL coated unidirectional fabrics can be improved by adding fillers in the NRL compounding. Multiwall carbon nanotubes (MWCNTs) dispersion in several concentrations of 3 wt%, 5 wt% and 7 wt% were added into the NRL. The effects of filler loading of the MWCNTs in NRL were investigated under quasi-static penetration resistance test. In general, it was shown that the forces needed to penetrate the NRL coated fabric increases with higher content of filler loading and were higher in comparison with uncoated fabric. The NRL coated unidirectional fabrics with 7 wt% MWCNTs gave about 44% higher penetration resistance in comparisons with uncoated fabric. Several modes of fabric failure were observed after the quasi-static penetration resistance such as yarn stretching, yarn breakages as well as peeling off of NRL layer.

Nano Natural Dyes from Melastoma Malabathricum L.

In this study, natural colours were produced from Melastoma Malabathricum L.’s (Senduduk) plant. The dyes were extracted from the petal part of the plant using solvent extraction method of acidified methanol and methanol. The natural colours were then converted into powder form of nano size scale using a ball mill grinder. Silk fabrics were used as the substrate and dyed using several natural and synthetic mordant. The use of different solvents for extraction and mordant for dyeing resulted in different colour shades on the silk fabrics. The color fastness to washing tests revealed colour fastness to washing ranging from 3 – 4/5 and the change in color ranging from 3/4 – 4/5. The findings will benefit and promote the dyeing and printing industry such as batik manufacturers and local fashion industry in using natural dyes. On the other hand, dyes from plants can also be used as an alternative to synthetic dyes for dyeing natural silk fibers.

Puncture resistance of nanofilled coated high strength woven fabric

This paper reports on the effects of nanofiller on the puncture resistance of high strength coated woven fabric. High strength Kevlar woven fabric was coated with natural rubber latex (NRL) and carbon nanotube (CNT) (1 phr, 3 phr, 5 phr) filled NRL. The coated fabrics were tested for puncture resistance test and the results were compared with neat fabrics. Three puncture probes with different geometry were used to test the fabrics which were conical probe, ogival probe and hemispherical probe. The NRL coated fabric gave higher puncture resistance in comparison with the neat fabric. The result also showed that the CNT filled influenced the properties of the coated fabric by increasing the resistance to puncture for all probe shapes. The 1 phr CNT turned out to give the highest puncture resistance. Among the puncture probe geometry, the hemispherical probe gave the highest puncture resistance in comparison with the ogival and conical probe.

Effect of crosslinking on the solubility and morphological structures of the PVA nanofibres

The electrospun PVA nanofibres are highly soluble in water. Hence, an improvement to stabilize the nanofibres in water has been investigated in the study. The PVA nanofibres were crosslinked with Hexamethylene diisocyanate(HMDI), N, N-Dimethylformamide(DMF) and a mixture of HMDI and DMF. The structures and properties of crosslinked electrospun PVA nanofibres were characterized using the SEM and FTIR. Changes of the membrane area, thickness and membrane stability in water were also investigated. The results show that the PVA nanofibres insoluble in water after crosslinking. The presence of N-H and C=O groups give stable nanofibres in water. However, the structures of nanofibres vary depending upon chemicals used. The HMDI gives similar fibre structures to the uncrosslinked PVA nanofibres. However, the DMF and a mixture of HMDI and DMF change the PVA nanofibre structures. The HMDI is also found to form crosslinking network between the PVA fibres that could improve the fibre-to-fibre bonding in the PVA membrane. From the results, it shows that the HMDI is not only improved the solubility of PVA nanofibres, but it can be used as binding agent for random-oriented fibres.

Tensile and Flexural Properties of Composites Made from Spinning Waste

ABSTRACT Spinning especially combed yarn produces considerable waste fibre. These fibres are sold at very low price for fillings. An investigation of converting these wastes to some form of value-added material was successful in forming a composite material made from natural fibre. Cotton combing noils and blowing waste were fabricated into thin composite boards using polyester resin at room temperature utilising a compression method. Tests on tensile and flexure properties of these composites were evaluated against 100% polyester resin plaques. It was found that composites made from cotton waste were stronger than polyester without the reinforcement. Some possible applications of these composites are thin boards or panels that can be used to replace wood and fibre-board products.

Partial Characterisation and Colorimetric Characteristics of Sargassum sp. Colorant on Treated Polyester Fabric with Dendrimer

This study focuses on the characterization of pigment compounds presence in Sargassum sp. extracts. The ground powder of dry Sargassum sp. was macerated in in methanol solution at 60°C for 48 hours in an aluminium foil-wrapped conical flask (to provide the dark environment). The extracted colourant was measured with UV-vis Spectrophotometer and Q-TOF LCMS to determine the compounds presence. The extracted colourant also used to dye pretreated and untreated polyester fabric with poly(amidoamine) dendrimer at different concentrations with and without mordants. The exhaustion dyeing with the simultaneous mordanting procedure was carried at 85°C for 60 minutes. The colorimetric properties of the dyed fabrics were then analysed. The results showed that the pigment compounds presence in Sargassum sp. extracts is fucoxanthin and chlorophyll. The application of dendrimer improved K/S values of the dyed fabric. Thus, Sargassum sp. extract is suitable to be used as natural dyes for textile dyeing.