pISSN : 1229-9197 / eISSN : 1875-0052
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Lignocellulosic Sugar Palm Fibre-Reinforced Thermoplastic Composites: Mechanical, Thermal and Dynamic Mechanical Properties
M. R. M. Asyraf K. Z. Hazrati Desmond Daniel Chin Vui Sheng M. Rafidah W. Ashraf Emrah Madenci Yasin Onuralp Özkılıç Ceyhun Aksoylu N. M. Nurazzi
Lignocellulosic fibre obtained from forest biomass has various advantages, especially in product development due to its abundance and ability in mechanical properties. Sugar palm fibre (SPF) has emerged as promising fibre reinforcement in composite industries to form high-strength and stiffness biocomposites. Due to environmental concerns such as air pollution and global warming, the global community has worked together to replace conventional plastic with biomass waste like SPF in various product types. Traditionally, sugar palm by-products are useful for various traditional uses such as traditional foods, gula kabung, and alcohol, while SPF is applied as rope, brooms and brushes. Numerous researchers have taken initiatives to implement SPF in the packaging sector and transport uses such as lifeguard boats. Some works have proved that SPF-reinforced polymer composites exhibit high mechanical strength and remarkable properties in thermal degradations. However, like other lignocellulosic fibres, the SPF exhibits high water absorption properties, which causes problems binding with thermoplastic matrix, reducing its performance. Based on the literature survey, no review has been carried out on discussing the mechanical and thermal behaviour of SPF-reinforced thermoplastic composites. Hence, the current review aims to establish concise and collective findings from previous works on SPF/thermoplastic composites to provide a good source of literature for further research on this topic.
Rezvan Mohamadinooripoor Soheila Kashanian Kobra Omidfar
Electrospinning is a well-known promising technique for the cost-effective and rapid fabrication of therapeutic-loaded nanofibers. Electrospun fibers have many merits that give them prospects in the production of therapeutic-loaded sutures. Despite the desirable properties of electrospun fibrous yarns, they have no prospective mechanical properties as a suture. Hence, improving the mechanical properties of the electrospun yarns is an open issue. This work applied electrospun composite mats consisting of poly-ε-caprolactone (PCL)/propolis ethanolic extract (PEE) with random and aligned morphological features of fibers to fabricate yarns. The PCL-PEE yarns were fabricated by twisting a ribbon-like part of these mats. Then, these yarns were characterized and evaluated as sutures. In vitro yarn release was followed during 221 h. Tensile testing of yarns was also studied. In addition, in vitro cell culture studies for the biocompatibility of MG-63 and human dermal fibroblast cells on the sutures and also antifungal and antibacterial effects of the sutures were assessed. These sutures were used for suturing an induced-wound rat model to follow in vivo effectiveness. Histopathological investigations were also done. Consequently, a PEE-PCL suture with elastomeric, mechanical, antibacterial, and antifungal properties and accelerated wound-healing features provides a proper and promising suture.
Xiaofei Shao Jiahui Shen Xiong Yan
In this study, polyvinyl butyral (PVB) was used as raw material, combined with electrospinning and microperforation process to prepare micro-/nanofiber membranes with excellent low-frequency sound absorption performance. To comprehensively explore the influence mechanisms of fiber diameter, multi-layer structure, and microperforated structure on the sound absorption performance, experiment and theoretical analysis were both conducted. Experimental results showed that appropriately reducing the fiber diameter, increasing the number of PVB membrane layers, and setting microperforated structure and cavity could improve the sound absorption performance in the low-frequency range. By adjusting the number of layers and the microperforation structure, the effective sound absorption band range of the fiber membrane can also be adjusted to better meet the sound absorption requirements. When the number of fiber layers was 20, the perforation rate was 1%, the perforation diameter was 0.6 mm, and the cavity depth was 40 mm, the PVB fiber membrane had peaks of 0.8483 and 0.9792 at 350 Hz and 480 Hz, respectively. Theoretical analysis showed that the acoustic electrical analogy model can well predict the resonance frequency and sound absorption peak of fiber membrane, and proved that microporous fiber membrane had both porous and resonant sound absorption mechanisms. These lightweight fiber membranes have great potential for application in sound absorption, such as in transportation, construction, and instrumentation.
Jinjian Wang Peng Wang Yingyu Luo Wei Huang Renjian Qian Jun Chen Peng Chen
To investigate the temperature and humidity stability of melt-blown polylactide (PLA) electret nonwovens with different crystallinity, PLA nonwovens were annealed at 70 ℃ for different time followed by the corona charging process, and decay experiments were carried out under different temperature and humidity conditions. It was found that the crystallinity of the PLA nonwovens increased from 14.0 to 50.8%, with annealing time increased from 0 to 4 h. Initial surface potential and filtration efficiency of the PLA electret nonwovens increased with increasing crystallinity (from 14.0 to 50.8%), with the maximum increment of 18% in the initial surface potential. Moreover, the temperature and humidity stability of the PLA electret nonwovens was enhanced with increasing crystallinity. As for the temperature stability, when humidity was constant and temperature increased from 30 to 50 ℃, a slight drop in the retention rate of the filtration efficiency was observed (≤ 3%) for the PLA electret nonwovens. Regarding the humidity stability, when temperature was constant and humidity exceeded 50% RH, the retention rate of the filtration efficiency for the PLA electret nonwovens decreased significantly (≥ 6%).
Geyi You Xiaoping Gao Jiawei Chen Ke Zhao
In this paper, the flow characteristics of resin in vacuum-assisted forming (VARI) process were studied by experiments and numerical simulation. The position and time of resin flow front were recorded by high-speed camera and timer. The viscosity of resin, porosity and permeability of composites were tested. Based on Darcy’s law, the resin permeability model in composite molding was derived, and the permeability was obtained by nonlinear fitting. The unit cell model of plain fabric was established and the flow characteristics of four kinds of viscosity resins were simulated by finite volume method. The flow profile and filling time were compared between experimental and numerical simulation, and the error between the model and the experiment is less than 12%, which verifies the accuracy of the model and shows that the model can be used to predict the flow behavior of resin with different viscosities in composite molding.
Stability Improvement of Betalains Recovered from Red Dragon Fruit Peels (Hylocereus polyrhizus) by Cellulose-Based Encapsulation
Trung Dang-Bao Uyen P. N. Tran
This study promoted a valorization pathway of Red Dragon Fruit Peel, including extraction of betalains and pectin, stabilization of batalains and expanding the application of betalains and pectin in jam and jellies. Betalains were extracted by the same weight of ethanol 96% at 45 ºC for 1 h and obtained with the content of 2.09 ± 0.03 mg/g of dry peels. To minimize the solid wastes, the alcohol-insoluble residues of betalains extraction were utilized to extract pectin by citric acid 0.1 M at 85 °C for 120 min with 19.8% yield and 56.8% DE (degree of esterification). Betalains stabilization focused on the encapsulation in support of the freeze-drying technique and microcrystalline cellulose (MCC) as a wall material. Freeze-dried MCC/betalains complexes were prepared by different weight ratios of betalains and MCC (1:3, 1:5, and 1:10). Encapsulation of betalains promoted significantly higher stability at different storage conditions: cold (4 °C) and room temperature (27 °C) with daylight and without daylight. The stability of encapsulated betalains was improved at high temperatures (80 °C and 100 °C), various pH levels (1.2, 3.6, 5.6, and 7.4) and water activities (0.089 and 0.898) when compared with the nonencapsulated betalains. The incorporation of encapsulated betalains into pineapple jam and gummy candy demonstrated storage stability after a two-week storage period.
Ultra-thin Metallized Glass Fabric Coated with Chitosan and Reduced Graphene Oxide for Electromagnetic Shielding with Excellent Heat Dissipation and Self-Cleaning
Meimei Chen Shan Jiang Ce Cui Wenhao Bai Jianyu Zhai Ronghui Guo
With the rapid development of modern technology, more and more electronic equipment had entered people’s life, causing serious electromagnetic pollution. In this study, a lightweight, ultra-thin and high electromagnetic shielding film was fabricated by copper electroless deposition after solution immersion coating method combining chitosan (CTS) and reduced graphene oxide on glass fabric (Cu/RGO-CTS-coated glass fabric). Chitosan and RGO had synergistic effect for copper deposition, enhancing electrical conductivity and electromagnetic shielding property. The prepared fabric showed superb conductivity of 8589.3 S/cm and the shielding effectiveness of the Cu/RGO-CTS-coated glass fabric showed as high as 93.6 dB at ultra-thin thickness of 92.4 μm (SSE/t = 3868.8 dB cm2 g-1). Thermal conductivity, antibacterial and hydrophobic properties were also studied. Compared with untreated glass fabric, thermal conductivity of Cu/RGO-CTS-coated glass fabric increased by 437%, protecting electronic equipment from adverse effects at high temperature. Cu/RGO-CTS-coated glass fabric had inhibitory effect on Staphylococcus aureus and Escherichia coli, which could prolong the service life and maintain the appearance of the fabric. Cu/RGO-CTS-coated glass fabric also showed hydrophobicity with self-cleaning function, making it possible for the composite material to be used in many fields such as aerospace industry, microelectronic devices, and transportation to resist electromagnetic interference in high humidity and high pollution environment.
Yoonjin Kim Gyu Dong Lee Song Jun Doh Jung Nam Im
In this study, activated carbon fiber (ACF) nonwovens were fabricated using a wet-laid nonwoven process to produce the gas removal layer for a face mask. Two types of polyethylene terephthalate fibers were used as binding fibers. The ammonia gas removal efficiency, mechanical properties, and particulate filtration performances of the fabricated ACF nonwovens were evaluated. The binders did not inhibit the ammonia gas removal efficiency of the ACF. The mechanical properties of the ACF nonwoven fabric could be adjusted based on the amount and composition of the binders. The composite nonwoven, including the ACF nonwoven layer, showed gas adsorption and excellent particulate filtration performances even after exposure to a moist environment. The composite nonwovens seemed to have the potential for a face mask with gas removal characteristics and excellent filtration performances.
Laser-Activated Organic Bleaching Process as an Environmentally Friendly Clean Alternative to Permanganate Bleaching in Denim Washing
Rıza Atav Öner Gündüz Sercan Yaz Gizem Çakan Bahadırhan Sevgili
Today, sustainable production has become an important concept. As the trends in the world bring about the widespread use of used-looking clothes, it has become mandatory to apply processes such as spray rodeo, which is the process done by spraying permanganate with a special spray gun or applying it with a brush to the desired area. However, permanganate has risk of causing irritation to the face and eyes, and cough, mucosal irritations, shortness of breath, etc. Therefore, it is of great importance to replace permanganate with clean alternatives. In this study, it was aimed to obtain high bleaching efficiency via laser-activated organic bleaching process and thus to obtain permanganate-like results in a sustainable way. It was found that the effects of organic bleaching agent concentration and pixel time on the degree of color fading are statistically significant and the optimum color fading could be achieved at 30% bleaching agent concentration and 300 μs pixel time. However, the bleaching agent concentration and/or pixel time can be changed according to the desired degree of color fading. Results indicated that by using laser-activated organic bleaching process, it is possible to obtain nearly same color fading effects with that of permanganate bleaching, which means a cleaner alternative has been developed.
A Sustainable Approach in the Development of Nano-silver Deposited Conductive Cellulosic Fabric: A Comparison of Various Bio-based Reductants
Zulfiqar Ali Raza Samra Rehan Muhammad Salman Naeem Kinza Hassan
The textile materials produced with nanoparticles’ mediation give them diverse functional features including antibacterial activity, optical and structural features, tensile properties, self-cleaning, electrical conductivity and so on. Accordingly, conductive textiles may promise widespread applications in electronics, sensing, diagnostics, data transfer and so on. Herein, we compared the effectiveness of three different bio-based reductants of black tea extract, chitosan and starch for the in situ synthesis and impregnation of silver nanoparticles (SNPs) on the cellulose fabric to get effective conducting textiles. The results demonstrated that the z-average of the prepared silver-based particles was found in the nanometer range and they were well stable in the aqueous media. The surface chemical analysis exhibited that the SNPs were successfully impregnated on the finished cellulose fabric and affected its surface roughness and crystalline properties. The AC conductivity scan of the finished fabrics expressed that they become conductive of electricity, however, the highest effect was seen when black tea extract as a reductant during the application of SNPs in the fabric. The SNPs-treated samples expressed slightly decreased air permeability and tensile strength as compared to the untreated sample. After silver nano-finishing, the cellulosic samples turned from whitish to yellow to dark brown. They exhibited good broad-spectrum qualitative and quantitative antibacterial activities.