scholarly journals An Overview of Alkali Treatments of Hemp Fibres and Their Effects on the Performance of Polymer Matrix Composites

2021 ◽  
Author(s):  
Tom Sunny ◽  
Kim L. Pickering

The alkali treatment is aimed to modify the surface chemistry of natural plant fibres effectively through several factors. This treatment has been carried out at ambient and high temperature. Natural plant fibres treated with alkali have been seen to have benefits such as improved separation of fibres from fibre bundles, improved removal of unwanted surface constituents, increased tensile strength and stiffness, better thermal stability, and enhanced interfacial adhesions compared to other standard treatments. Hemp fibres are an attractive reinforcement for natural plant fibres as they are environmentally friendly compared to other natural plant fibres and exhibit good mechanical properties. This chapter mainly provides an overview of alkali treatments on hemp fibres.

Polymers ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 117
Author(s):  
Le Thuy Hang ◽  
Do Quoc Viet ◽  
Nguyen Pham Duy Linh ◽  
Vu Anh Doan ◽  
Hai-Linh Thi Dang ◽  
...  

In this study, we present the fabrication of nitrile butadiene rubber/waste leather fiber (NBR/WLF) composites with different weight percentages of WLF and NBR (0/100, 20/80, 30/70, 40/60, 50/50, 60/40 wt/wt). WLF was prepared by cutting the scrap leathers from the waste product of the Vietnamese leather industry. Subsequently, in order to make the short fibers, it was mixed by a hammer mill. The characteristics of WLF/NBR composites such as mechanical properties (tensile strength, tear strength, hardness), dynamic mechanical properties, toluene absorption, and morphology were carefully evaluated. As a result, the tensile strength and tear strength become larger with increasing WLF content from 0 to 50 wt% and they decrease when further increasing WLF content. The highest tensile strength of 12.5 MPa and tear strength of 72.47 N/mm were achieved with the WLF/NBR ratio of 50/50 wt%. Both hardness and resistance of the developed materials with toluene increased with increasing WLF content. The SEM results showed a good adhesion of NBR matrix and the WLF. The increasing of storage modulus (E’) in comparison with raw NBR showed good compatibility between WLF and NBR matrix. This research showed that the recycled material from waste leather and NBR was successfully prepared and has great potential for manufacturing products such as floor covering courts and playgrounds, etc.


2015 ◽  
Author(s):  
Risa Yoshizaki ◽  
Kim Tae Sung ◽  
Atsushi Hosoi ◽  
Hiroyuki Kawada

Carbon nanotubes (CNTs) have very high specific strength and stiffness. The excellent properties make it possible to enhance the mechanical properties of polymer matrix composites. However, it is difficult to use CNTs as the reinforcement of long fibers because of the limitation of CNT growth. In recent years, a method to spin yarns from CNT forests has developed. We have succeeded in manufacturing the unidirectional composites reinforced with the densified untwisted CNT yarns. The untwisted CNT yarns have been manufactured by drawing CNTs through a die from vertically aligned CNT arrays. In this study, the densified untwisted CNT yarns with a polymer treatment were fabricated. The tensile strength and the elastic modulus of the yarns were improved significantly by the treatment, and they were 1.9 GPa and 140 GPa, respectively. Moreover, the polymer treatment prevented the CNT yarns from swelling due to impregnation of the matrix resin. Finally, the high strength CNT yarn composites which have higher volume fraction than a conventional method were successfully fabricated.


2021 ◽  
Vol 877 ◽  
pp. 3-8
Author(s):  
Prathumrat Nuyang ◽  
Atiwat Wiriya-Amornchai ◽  
Watthanaphon Cheewawuttipong

The effect of compatibilizer agent was studied when adding Aluminum fine powder (Al) to reinforce in Polypropylene (PP) by compared between polymer matrix composites (PMCs) and PMCs added Polypropylene graft maleic anhydride (PP-g-MAH).The average particle size of the aluminum fine powder was around 75 μm filled in polypropylene with different proportions of 2.5, 5, 7.5 and 10wt%. PMCs were prepared using the internal mixer. The results found that when the amount of aluminum fine powder increased, the mechanical properties had changed, i.e., tensile strength, and Young’s Modulus increased, while the impact strength and elongation at break decreased. But, when adding compatibilizer 1wt% it was found that the trend of tensile strength, and Young’s Modulus increased that compared with non-compatibilizer, but the impact strength and elongation at break decreased. The part of the morphology of PMCs with non-compatibilizer was found that the particle of aluminum fine powder dispersed in the matrix phase, but there were many microvoids between filler and matrix. But, PMCs with compatibilizer caused the microvoids between filler and matrix to be reduced.


Metals ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 31
Author(s):  
Hongxin Liao ◽  
Taekyung Lee ◽  
Jiangfeng Song ◽  
Jonghyun Kim ◽  
Fusheng Pan

The microstructures and mechanical properties of the Mg88.5Zn5Y6.5-XREX (RE = Yb and Ce, X = 0, 1.5, 3.0, and 4.5) (wt.%) alloys were investigated in the present study. Mg88.5Zn5Y6.5 is composed of three phases, namely, α-Mg, long-period stacking ordered (LPSO) phases, and intermetallic compounds. The content of the LPSO phases decreased with the addition of Ce and Yb, and no LPSO phases were detected in Mg88.5Zn5Y2.0Yb4.5. The alloys containing the LPSO phases possessed a stratified microstructure and exhibited excellent mechanical properties. Mg88.5Zn5Y5.0Ce1.5 exhibited the highest creep resistance and mechanical strength at both room temperature and 200 °C, owing to its suitable microstructure and high thermal stability. The yield strength of Mg88.5Zn5Y5.0Ce1.5 at room temperature was 358 MPa. The ultimate tensile strength of Mg88.5Zn5Y5.0Ce1.5 at room temperature and 200 °C was 453 MPa and 360 MPa, respectively.


Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1064
Author(s):  
Mohd Nor Faiz Norrrahim ◽  
Hidayah Ariffin ◽  
Tengku Arisyah Tengku Yasim-Anuar ◽  
Mohd Ali Hassan ◽  
Nor Azowa Ibrahim ◽  
...  

Residual hemicellulose could enhance cellulose nanofiber (CNF) processing as it impedes the agglomeration of the nanocellulose fibrils and contributes to complete nanofibrillation within a shorter period of time. Its effect on CNF performance as a reinforcement material is unclear, and hence this study seeks to evaluate the performance of CNF in the presence of amorphous hemicellulose as a reinforcement material in a polypropylene (PP) nanocomposite. Two types of CNF were prepared: SHS-CNF, which contained about 11% hemicellulose, and KOH-CNF, with complete hemicellulose removal. Mechanical properties of the PP/SHS-CNF and PP/KOH-CNF showed an almost similar increment in tensile strength (31% and 32%) and flexural strength (28% and 29%) when 3 wt.% of CNF was incorporated in PP, indicating that hemicellulose in SHS-CNF did not affect the mechanical properties of the PP nanocomposite. The crystallinity of both PP/SHS-CNF and PP/KOH-CNF nanocomposites showed an almost similar value at 55–56%. A slight decrement in thermal stability was seen, whereby the decomposition temperature at 10% weight loss (Td10%) of PP/SHS-CNF was 6 °C lower at 381 °C compared to 387 °C for PP/KOH-CNF, which can be explained by the degradation of thermally unstable hemicellulose. The results from this study showed that the presence of some portion of hemicellulose in CNF did not affect the CNF properties, suggesting that complete hemicellulose removal may not be necessary for the preparation of CNF to be used as a reinforcement material in nanocomposites. This will lead to less harsh pretreatment for CNF preparation and, hence, a more sustainable nanocomposite can be produced.


2013 ◽  
Vol 706-708 ◽  
pp. 95-98
Author(s):  
Mi Dan Li ◽  
Dong Mei Liu ◽  
Lu Lu Feng ◽  
Huan Niu ◽  
Yao Lu

Polymer matrix composites made from phenolic resin are filled with natural graphite powders. They are fabricated by compression molding technique. The density, electrical conductivity and flexural strength of composite are analyzed to determine the influences of mould pressure and mould pressing time on the physical, electrical and mechanical properties of composite. It is found that the density, electrical conductivity and flexural strength of composites increased with increasing mould pressure. Under pressure of 40 MPa for 60 min, the density, electrical conductivity and flexural strength of composites were 1.85 g/cm3, 4.35  103 S/cm and 70 MPa, respectively. The decreased gaps could be the main reason for the increasing of density, electrical conductivity and flexural strength as mould pressure increases. The results also show that the density of composites increased with increasing mould pressing time.


Molecules ◽  
2020 ◽  
Vol 25 (14) ◽  
pp. 3236
Author(s):  
Peng Yin ◽  
Wen Zhou ◽  
Xin Zhang ◽  
Bin Guo ◽  
Panxin Li

In order to improve the mechanical properties and water resistance of thermoplastic starch (TPS), a novel reinforcement of dialdehyde lignocellulose (DLC) was prepared via the oxidation of lignocellulose (LC) using sodium periodate. Then, the DLC-reinforced TPS composites were prepared by an extrusion and injection process using glycerol as a plasticizer. The DLC and LC were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), and the effects of DLC content on the properties of the DLC/TPS composites were investigated via the evaluation of SEM images, mechanical properties, thermal stability, and contact angles. XRD showed that the crystallinity of the DLC decreased due to oxidation damage to the LC. SEM showed good dispersion of the DLC in the continuous TPS phase at low amounts of DLC, which related to good mechanical properties. The tensile strength of the DLC/TPS composite reached a maximum at a DLC content of 3 wt.%, while the elongation at break of the DLC/TPS composites increased with increasing DLC content. The DLC/TPS composites had better thermal stability than the neat TPS. As the DLC content increased, the water resistance first increased, then decreased. The highest tensile strength and elongation at break reached 5.26 MPa and 111.25%, respectively, and the highest contact angle was about 90.7°.


DYNA ◽  
2019 ◽  
Vol 86 (210) ◽  
pp. 156-163 ◽  
Author(s):  
Leidy Johana Quintero Giraldo ◽  
Luis Javier Cruz ◽  
Jaime Alexis García ◽  
Alejandro Alcaraz ◽  
Eugenia González ◽  
...  

In this article, bamboo fibre bundles of "Guadua Angustifolia Kunth" specie were isolated from different locations of the basa zone: upper, middle and lower, through mechanical extraction method. The elastic modulus and the tensile strength were obtained with preliminary tensile tests. Applying the statistical analysis known as ANOVA, it was determined that the mechanical properties are similar in all the extension of the basa zone. From there, fibre bundles were extracted randomly, and a part of the fibre bundles was treated with NaOH (mercerization). Later, tensile tests with different calibration lengths were made for calculate the elastic modulus and the tensile strength of the treated and untreated fibre bundles. Best results belonged to the treated fibre bundles. A good correspondence between the results obtained in this work and the results reported in the literature was concluded. 


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