scholarly journals New Concept in Bioderived Composites: Biochar as Toughening Agent for Improving Performances and Durability of Agave-Based Epoxy Biocomposites

Polymers ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 198
Author(s):  
Bernardo Zuccarello ◽  
Mattia Bartoli ◽  
Francesco Bongiorno ◽  
Carmelo Militello ◽  
Alberto Tagliaferro ◽  
...  

Biocomposites are increasingly used in the industry for the replacement of synthetic materials, thanks to their good mechanical properties, being lightweight, and having low cost. Unfortunately, in several potential fields of structural application their static strength and fatigue life are not high enough. For this reason, several chemical treatments on the fibers have been proposed in literature, although still without fully satisfactory results. To overcome this drawback, in this study we present a procedure based on the addition of a carbonaceous filler to a green epoxy matrix reinforced by Agave sisalana fibers. Among all carbon-based materials, biochar was selected for its environmental friendliness, along with its ability to improve the mechanical properties of polymers. Different percentages of biochar, 1, 2, and 4 wt %, were finely dispersed into the resin using a mixer and a sonicator, then a compression molding process coupled with an optimized thermomechanical cure process was used to produce a short fiber biocomposite with Vf = 35%. Systematic experimental tests have shown that the presence of biochar, in the amount 2 wt %, has significant effects on the matrix and fiber interphase, and leads to an increase of up to three orders of magnitude in the fatigue life, together with an appreciable improvement in static tensile strength.


2020 ◽  
Vol 10 (3) ◽  
pp. 1159 ◽  
Author(s):  
Yingmei Xie ◽  
Hiroki Kurita ◽  
Ryugo Ishigami ◽  
Fumio Narita

Epoxy resins are a widely used common polymer due to their excellent mechanical properties. On the other hand, cellulose nanofiber (CNF) is one of the new generation of fibers, and recent test results show that CNF reinforced polymers have high mechanical properties. It has also been reported that an extremely low CNF addition increases the mechanical properties of the matrix resin. In this study, we prepared extremely-low CNF (~1 wt.%) reinforced epoxy resin matrix (epoxy-CNF) composites, and tried to understand the strengthening mechanism of the epoxy-CNF composite through the three-point flexural test, finite element analysis (FEA), and discussion based on organic chemistry. The flexural modulus and strength were significantly increased by the extremely low CNF addition (less than 0.2 wt.%), although the theories for short-fiber-reinforced composites cannot explain the strengthening mechanism of the epoxy-CNF composite. Hence, we propose the possibility that CNF behaves as an auxiliary agent to enhance the structure of the epoxy molecule, and not as a reinforcing fiber in the epoxy resin matrix.



2017 ◽  
Vol 743 ◽  
pp. 264-268 ◽  
Author(s):  
Anastasia Smirnova ◽  
Yury Pochivalov ◽  
Victor Panin ◽  
Anatoly Orishich ◽  
Aleksandr Malikov ◽  
...  

The structure and mechanical properties of welded joints of VT23 titanium alloy received by method of laser welding after modifying the surface layers by ultrasonic mechanical forging (Treatment 1 and Treatment 2) were investigated. The experimental tests have revealed that the Treatment 2 provides a multiple increase in the relaxation property in fatigue life test. The formation of nonuniform distribution of vanadium, chromium and molybdenum in the welded joint increases the strength and, at the same time, the brittleness of β-phase. Mechanical treatment of the surface layers in the second mode provides a multiple increase in ductility up to 13%, in the as-received condition up to 9.9%. In consequence of plastic deformation, the β-phase intensity reduces twice with Treatment 2 which is related to its clustering. As follows from a presented data, the fatigue life of the VT23 titanium alloy has increased more than threefold.



Author(s):  
Ying Yu ◽  
Manabu Nomura ◽  
Hiroyuki Hamada

Recent years, thermoplastics incorporated with particulate fillers have been gained high interests. To improve the mechanical properties of the natural particle reinforced polymer plastics, hybrid structure has been applied on the composite combining natural particle with stronger synthetic fibers. However, the reinforcing mechanism of the hybrid composite is quite complicated. Experiments on it may become time consuming and cost prohibitive. Therefore, researchers are interested in studying variable models to predict the elastic properties of the composites. In this study, glass short fiber/wood particle/pp hybrid composites were prepared by injection molding process at a fixed reinforcement to matrix ratio of 51:49. 4 kinds of hybrid specimens with glass fiber/wood particle ratios of 41:10, 31:20, 21:30 and 11:40 were fabricated. The effect of hybridization content on the mechanical properties of the composites was evaluated based on tensile test. Theoretically, the elastic modulus of hybrid composites was predicted by using the rule of hybrid mixtures (RoHM) equation and classical lamination theory (CLT) and the accuracy of the two estimation models has been discussed. Results showed that it can be considered the hybridization of wood powder into glass/PP composite could contribute to a similar high elastic modulus with high green degree. On the other hand, the fiber orientation factor, fiber length distribution factor, powder dispersion factor were very important factors and need to be considered in the prediction model.



2012 ◽  
Vol 486 ◽  
pp. 533-537 ◽  
Author(s):  
Hsi Hsin Chien ◽  
Kung Jeng Ma ◽  
Chien Hung Kuo

Glass molding process provides a great potential for the production of precise glass optical components at low cost. The platinum-iridium (Pt-Ir) alloys are widely used as the protective coatings to extend the service life of the mold in glass molding process. This study concentrated on the microstructure and mechanical properties of sputtered Pt-Ir alloy films. The obvious grain growth was observed in the Pt-Ir alloy films at sputtering temperature of 700. The hardness and elastic modulus of Pt-Ir alloy film decreased with the increase in Pt content.







2021 ◽  
Vol 59 (6) ◽  
pp. 357-364
Author(s):  
Godwin Kwame Ahiale ◽  
In-Seok Kye ◽  
Young Sam Kwon ◽  
Yong-Jun Oh

W-containing Ti-6Al-4V alloys (W=0, 1, and 5 wt%) were fabricated by the powder injection molding process, and the corresponding effects of tungsten content on the mechanical properties and microstructure of the alloys were investigated. The alloy powders were sintered at 1200 °C and then hot-isostatically-pressed at 900 °C. The fabricated alloys were subjected to microstructural and chemical analyses, and tensile and nano-indentation tests. The yield strength and tensile strength proportionally increased as the W content was increased from 0 wt% to 5 wt%. Ductility was not affected by the addition of up to 5 wt% W due to its complete dissolution in the matrix. Higher W addition induced finer α/β lamellar microstructures and increased the β to α phase ratio. Moreover, the added W dissolved preferentially in the β phase by solid solution hardening, increasing the hardness of the β phase, which originally was significantly softer than the α phase. For the alloys containing up to 5 wt% W, the strengthening without ductility loss was attributed to the finer α/β lamellae and the volume increase in the β phase hardened by W. These results suggest that adding W to Ti-6Al-4V alloy is a promising method for developing Ti alloys with both high strength and toughness.



Author(s):  
Adam Kramschuster ◽  
Lih-Sheng Turng ◽  
Wan-Ju Li ◽  
Yiyan Peng ◽  
Jun Peng

The current large demands for transplant organs and tissues has led to extensive research on material synthesis and fabrication methods for biodegradable polymeric scaffolds, which are required to have high porosity, well interconnected pore structure, and good mechanical properties. However, the majority of current scaffold fabrication techniques are either for batch processes or use organic solvents, which can be detrimental to cell survival and tissue growth. The ability to mass produce solvent-free, highly porous, highly interconnected scaffolds with complex geometries is essential to provide off-the-shelf availability [1]. Injection molding has long been used for mass production of complex 3D plastic parts. The low-cost manufacturing, repeatability, and design flexibility inherent in the injection molding process make it an ideal manufacturing process to create 3D scaffolds, as long as high porosity and interconnectivity can be imparted into the finished product.



Author(s):  
Pantea Kooshki ◽  
Tsz-Ho Kwok

This paper is a review on mechanical characteristics of natural fibers reinforced elastomers (both thermoplastics and thermosets). Increasing environmental concerns and reduction of petroleum resources attracts researchers attention to new green eco-friendly materials. To solve these environmental related issues, cellulosic fibers are used as reinforcement in composite materials. These days natural fibers are at the center of attention as a replacement for synthetic fibers like glass, carbon, and aramid fibers due to their low cost, satisfactory mechanical properties, high specific strength, renewable resources usage and biodegradability. The hydrophilic property of natural fibers decreases their compatibility with the elastomeric matrix during composite fabrication leading to the poor fiber-matrix adhesion. This causes low mechanical properties which is one of the disadvantages of green composites. Many researches have been done modifying fiber surface to enhance interfacial adhesion between filler particles and elastomeric matrix, as well as their dispersion in the matrix, which can significantly affect mechanical properties of the composites. Different chemical and physical treatments are applied to improve fiber/matrix interlocking.



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