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.
The effect of sodium carbonate (Na 2 CO 3 ) treatment of short bamboo fibres on mechanical properties and water absorption character of polyester composite is investigated. Treatment time and Na 2 CO 3 concentration were optimised to 6 h and 5 wt-% respectively. Microscopy of the treated fibres showed a significant change in surface texture whereas; FTIR suggested the removal of amorphous compounds from the fibres that resulted in enhanced interfacial bonding between fibres and the polyester matrix. Removal of amorphous compounds was also confirmed by TGA where material loss for untreated fibres was 15% higher than the treated fibres. Composites were prepared using 10, 20 and 30 wt-% of treated and untreated fibres. Good interfacial bonding, achieved by the fibre treatment, enhanced the strength (∼24 MPa),( decreased the impact energy (from ∼36×10 −3 KJ/m 2 to ∼33×10 −3 KJ/ m 2 ) and improved the water absorption resistance (∼2%) in case of 20 wt-% fibres composite.
Nanocellulose is the most abundant material extracted from plants, animals, and bacteria. Nanocellulose is a cellulosic material with nano-scale dimensions and exists in the form of cellulose nanocrystals (CNC), bacterial nanocellulose (BNC), and nano-fibrillated cellulose (NFC). Owing to its high surface area, non-toxic nature, good mechanical properties, low thermal expansion, and high biodegradability, it is obtaining high attraction in the fields of electronics, paper making, packaging, and filtration, as well as the biomedical industry. To obtain the full potential of nanocellulose, it is chemically modified to alter the surface, resulting in improved properties. This review covers the nanocellulose background, their extraction methods, and possible chemical treatments that can enhance the properties of nanocellulose and its composites, as well as their applications in various fields.
Life‐changing illnesses and fatalities caused by inefficient personal protective clothing and equipment are increasing day by day. The discrepancy between the test standards, environmental conditions, and infield collision is the reason why personal protection equipment and clothing have not yet decreased the number of injuries in various fields such as military and sports. To further increase the efficiency of personal protection materials, auxetic materials are suggested because of their high energy absorption, good permeability, form‐fitting ability, and high indentation resistance. Auxetic materials are nonconventional materials with a negative Poisson's ratio and can shrink under compression and expand when subjected to stretching. In comparison to nonauxetic conventional materials, auxetic materials have improved properties that can be useful for personal protection applications. This review focuses on the importance of auxetic materials for personal protection, focusing on reducing the chances of injury and what possible ideas can further benefit the protection products. The first part of the review discusses the auxetic structures and their protection applications followed by the fabrication of auxetic structures. The review will conclude with limitations, economic prospects, and what possible work can further improve the potential use of auxetic materials in personal protection.
Epoxy-bamboo long natural fibres composites were prepared by hand lay-up method to study the influence of fibre's treatment on their characteristics. SEM showed increased surface roughness due to the removal of amorphous compounds from the treated fibre as confirmed by the disappearance of certain peaks in FTIR spectroscopy. Resultantly, ∼52% increase in crystallinity was observed by XRD analysis. TGA results also showed the effectiveness of the treatment as mass loss for treated fibres was ∼15% lesser than the untreated fibres. Moreover, thermogravimetric analysis of composites showed highest mass loss in untreated fibres composites and lowest in neat epoxy. The DSC-DTA curves indicated an early start of initiation temperature in treated fibre composite. Tension tests showed ∼12% and ~16% increase in tensile strength and modulus respectively for treated fibres composite due to increased interfacial strength caused by fibre treatment. Treatment also resulted in decreased impact energy and water absorption level.
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