scholarly journals High-Quality Natural Fibers from Cotton Stalk Bark via Limited Alkali Penetration and Simultaneous Accelerated Temperature Rise

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 422
Author(s):  
Zhen Dong ◽  
Na Li ◽  
Teye Chu ◽  
Jiangxin Ding ◽  
Junxiong Zhang ◽  
...  

High-quality cotton stalk fibers that are both fine and have a high breakage strength are extracted via limited alkali penetration in the glycerol solvent and simultaneous accelerated temperature rise by means of microwave-assisted heating. Alkali is widely used in the extraction of cotton stalk fibers. However, alkali molecules in the aqueous phase penetrate easily into the fiber bundles, resulting in a simultaneous degumming between the inner and outer layers of the fiber bundles. In previous reports, the fibers treated in the aqueous phase present a coarse fineness (51.0 dtex) under mild conditions or have a poor breakage strength (2.0 cN/dtex) at elevated temperatures. In this study, glycerol is chosen as a solvent to reduce the penetration of alkali. Simultaneously, the microwave-assisted heating form is adopted to increase the temperature to 170 °C within 22 s. The inhibited alkali penetration and accelerated temperature rise limited the delignification to the outer layer, resulting in fibers with both appropriate fineness (23.8 dtex) and high breakage strength (4.4 cN/dtex). Moreover, the fibers also exhibit a clean surface and large contact angle. In this paper, we detail a new strategy to extract high-quality lignocellulosic fibers that will be suitable for potential reinforcing applications.

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 3855
Author(s):  
Amirmohamad Abolhasani ◽  
Bijan Samali ◽  
Fatemeh Aslani

One commonly used cement type for thermal applications is CAC containing 38–40% alumina, although the postheated behavior of this cement subjected to elevated temperature has not been studied yet. Here, through extensive experimentation, the postheated mineralogical and physicochemical features of calcium aluminate cement concrete (CACC) were examined via DTA/TGA, X-ray diffraction (XRD), and scanning electron microscopy (SEM) imaging and the variation in the concrete physical features and the compressive strength deterioration with temperature rise were examined through ultrasonic pulse velocity (UPV) values. In addition, other mechanical features that were addressed were the residual tensile strength and elastic modulus. According to the XRD test results, with the temperature rise, the dehydration of the C3AH6 structure occurred, which, in turn, led to the crystallization of the monocalcium dialuminate (CA2) and alumina (Al2O3) structures. The SEM images indicated specific variations in morphology that corresponded to concrete deterioration due to heat.


Polymers ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1311 ◽  
Author(s):  
Fabio da Costa Garcia Filho ◽  
Fernanda Santos da Luz ◽  
Lucio Fabio Cassiano Nascimento ◽  
Kestur Gundappa Satyanarayana ◽  
Jaroslaw Wieslaw Drelich ◽  
...  

Natural lignocellulosic fibers and corresponding fabrics have been gaining notoriety in recent decades as reinforcement options for polymer matrices associated with industrially applied composites. These natural fibers and fabrics exhibit competitive properties when compared with some synthetics such as glass fiber. In particular, the use of fabrics made from natural fibers might be considered a more efficient alternative, since they provide multidirectional reinforcement and allow the introduction of a larger volume fraction of fibers in the composite. In this context, it is important to understand the mechanical performance of natural fabric composites as a basic condition to ensure efficient engineering applications. Therefore, it is also important to recognize that ramie fiber exhibiting superior strength can be woven into fabric, but is the least investigated as reinforcement in strong, tough polymers to obtain tougher polymeric composites. Accordingly, this paper presents the preparation of epoxy composite containing 30 vol.% Boehmeria nivea fabric by vacuum-assisted resin infusion molding technique and mechanical behavior characterization of the prepared composite. Obtained results are explained based on the fractography studies of tested samples.


2021 ◽  
pp. 131294
Author(s):  
Badr A. Mohamed ◽  
Xiaotao Bi ◽  
Loretta Y. Li ◽  
Lijian Leng ◽  
El-Sayed Salama ◽  
...  

2017 ◽  
Vol 5 (42) ◽  
pp. 10947-10954 ◽  
Author(s):  
Qi Pan ◽  
Huicheng Hu ◽  
Yatao Zou ◽  
Min Chen ◽  
Linzhong Wu ◽  
...  

A fast and efficient microwave-assisted strategy is developed to prepare high-quality CsPbX3 nanocrystals with controllable morphologies (nanoplate, nanocube, and nanorod).


2021 ◽  
Author(s):  
Karolina E. Mazur ◽  
Aleksandra Borucka ◽  
Paulina Kaczor ◽  
Szymon Gądek ◽  
Stanislaw Kuciel

Abstract In the study, polylactide-based (PLA) composites modified with natural particles (wood, bamboo, and cork) and with different levels of infilling (100%, 80%, and 60%) obtained by additive methods were tested. The effect of type fiber, infill level and crystallization rate on the mechanical properties were investigated by using tensile, flexural, and impact tests. The materials were subjected to mechanical tests carried out at 23 and 80 °C. Furthermore, hydrothermal degradation was performed, and its effect on the properties was analyzed. The addition of natural fillers and different level of infilling result in a similar level of reduction in the properties. Composites made of PLA are more sensitive to high temperature than to water. The decrease in Young's modulus of PLA at 80 °C was 90%, while after 28 days of hydrodegradation ~ 9%. The addition of fibers reduced this decrease at elevated temperatures. Moreover, the impact strength has been improved by 50% for composites with cork particles and for other lignocellulosic composites remained at the same level as for resin.


2018 ◽  
Vol 5 (10) ◽  
pp. 2641-2647 ◽  
Author(s):  
Wenna Liu ◽  
Jinju Zheng ◽  
Sheng Cao ◽  
Lin Wang ◽  
Fengmei Gao ◽  
...  

A novel microwave-assisted hot injection strategy for mass production of high quality Mn2+:CsPbCl3 NCs was reported.


2016 ◽  
Vol 86 (12) ◽  
pp. 2737-2743 ◽  
Author(s):  
B. Sakram ◽  
S. Rambabu ◽  
K. Ashok ◽  
B. Sonyanaik ◽  
D. Ravi

2019 ◽  
Vol 895 ◽  
pp. 15-20
Author(s):  
Raghavendra Subramanya ◽  
S.S. Prabhakara

Natural fibers, in particularly lignocellulosic fibers are attracting material scientists now days, due to their comparative advantages over synthetic fibers. Biodegradable composites reinforced with short banana fibre after alkali treatment along with cassava starch matrix were prepared using the hot compression method. The mechanical properties like tensile strength and impact strength were investigated. Mechanical properties of the composites made from alkali treated fibres were superior to the untreated fibres. SEM observations on the fracture surface of composites showed that the surface modification of the fibre occurred and improved fibre–matrix adhesion. Keywords: Surface modification; banana fiber; Biodegradable composites; Mechanical properties; Matrix.


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