Chemical Modification Of Fiber Surface Research Articles

Crack propagation analysis and mechanical properties of basalt fiber reinforced cement composites with changing fiber surface characteristics

The large-scale application of basalt fiber reinforced cement composites (BFRCC) is due to the relatively high performance and decreased CO2 footprint of basalt fiber. Still, the ultimate tensile strain of BFRCC is always difficult to exceed 1%, hindering its popularity. Chemical grafting on the basalt fiber surface is a promising way to deal with the such drawback. The crack propagation mechanism of BFRCC is also unclear. Thus, the influence of fiber interface characteristics on the tensile failure mechanism of BFRCC is analyzed. The main work of this study is to achieve ultra-high toughness BFRCC with ultimate tensile strain exceeding 2% through chemical modification of fiber surface. The decrease in bonding strength has little effect on the water absorption of BFRCC but can improve its compressive and tensile properties to 1.88 times and 1.95 times. The crack resistance mechanism of modified BFRCC was revealed. The results showed that the average crack propagation speed of modified BFRCC was one order of magnitude lower, and the initiation energy threshold and crack propagation energy were higher. Proper interfacial bonding strength and high sliding friction coefficient can suppress the cracking width and fiber breaking rate.

Natural fibres as promising environmental-friendly reinforcements for polymer composites

Polymer composites are an important class of materials widely being used for many applications. But the main concern of non-degradability and adverse environmental impact of the polymer matrices and the synthetic reinforcements have given forth the need of environmental-friendly polymer matrices and reinforcements used in them. An attempt of such kind is to use the natural plant fibres as the reinforcements that have no harmful impact on the environment and also, they are cost effective. With growing interest in natural fibres in recent years, a lot of work is being done in various directions, which need to be gathered up for a specific interest. So, the present article is an attempt to review and discuss the research works that have evaluated the natural plant fibres as reinforcements in polymer composites. Natural fibre composites show variation of properties such as fibre’s source, type and structure. Interfacial adhesion between the fibre and the matrix is the most important factor when tensile properties of natural fibre composites are under consideration. The interfacial strength can be improved by some chemical modification of fibre surface, which changes the adhesion between fibre and matrix. These features of natural fibres as compared to synthetic fibres are motivating manufacturers and the end users to switch to natural fibre-based products.

Effect of chemical modification of fiber surface on natural fiber composites: A review

Abstract The effect of different chemical modification of fiber surface on different mechanical properties of natural fibers composites are reviewed in this paper. Different fiber surface modifications like alkali, acetylation, potassium permanganate, peroxides, silane benzoylation etc. and the composition of the natural fibers components like cellulose, hemi-cellulose, lignin, pectin etc. are discussed. The main purpose of present study is to check the effect of the different fiber surface modification on natural composites. Different properties of the natural fiber composites are increases like the adhesion force between the reinforcement surface and matrix material at the surface contact, also it improve fiber strength. The water absorption properties of composites are reduced.

Design of functionalized biodegradable PHA-based electrospun scaffolds meant for tissue engineering applications

Modification of electrospun nanofibrous poly(3-hydroxyalkanoate) (PHA)-based mats was implemented through two routes to obtain biomimetic scaffolds meant for tissue engineering applications. The first strategy relied on a physical functionalization of scaffolds thanks to an original route which combined both electrospinning and electrospraying, while the second approach implied the chemical modification of fiber surface via the introduction of reactive functional groups to further conjugate bioactive molecules. The degree of glycidyl methacrylate grafting on PHA reached 20% after 300s under photoactivation. Epoxy groups were modified via the attachment of a peptide sequence, such as Arg-Gly-Asp (RGD), to obtain biofunctionalized scaffolds. SEM and TEM analysis of mats showed uniform and well-oriented beadless fibers. The electrospinning/electrospraying tandem process afforded highly porous scaffolds characterized by a porosity ratio up to 83% and fibers with a surface largely covered by the electrosprayed bioceramic, i.e. hydroxyapatite. Gelatin was added to the latter PHA-based scaffolds to improve the hydrophilicity of the scaffolds (water contact angle about 0°) as well as their biological properties, in particular cell adhesion, proliferation, and osteogenic differentiation after 5days of human mesenchymal stromal culture. Human mesenchymal stromal cells exhibited a better adhesion and proliferation on the biofunctionalized scaffolds than that on non-functionalized PHA mats.

Fiber surface treatment and its effect on mechanical and visco-elastic behaviour of banana/epoxy composite

Natural fibers offer many advantages over synthetic fibers but the notable disadvantage of natural fibers is its hydrophilic nature. Due to this nature an incompatibility between the fiber and matrix exist which decreases the properties of the composite. This defect can be overcome by chemical modification of fiber surface so as to make it less hydrophilic. In this work, alkali (NaOH) of various concentrations (0.5%, 1%, 2%, 5%, 10%, 15% and 20%) was used to treat the fiber surface and the effect of these concentrations on the mechanical and visco-elastic behaviour of the composites were carried out. From the experimental investigation, it is found that 1% NaOH treated fiber reinforced composites behaves superiorly than other treated and untreated fiber composite. Further, SEM image analysis also shows the effect of alkali concentration over the fiber surfaces which leads to improving the mechanical properties of the composite.

Effect of chemical modification on properties of hybrid fiber biocomposites

The effects of chemical modification of fiber surface in sisal–oil palm reinforced natural rubber green composites have been studied. Composites were prepared using fibers treated with varying concentrations of sodium hydroxide solution and different silane coupling agents. The vulcanisation parameters, processability conditions and tensile properties and swelling characteristics of these composites were analysed. The fiber reinforcing efficiency of the chemically treated biocomposites was compared with that of untreated composites. The extent of fiber alignment and strength of fiber–rubber interfacial adhesion was analysed from the swelling measurements. Composites containing chemically treated fibers were found to possess enhanced mechanical properties. The hardness and abrasion resistance of the untreated and treated composites were also analyzed. Surface characterization of treated and untreated sisal fibers by XPS showed the presence of numerous elements on the surface of the fiber. The fracture mechanism of treated and untreated fiber reinforced rubber biocomposites was investigated from SEM studies.