ReviewBamboo fibre reinforced biocomposites: A review
Introduction
The soaring prices of raw materials for engineering and standard plastics, the future sustainability of natural reservoirs and threat to environment have forced to use natural redeemable materials for development and fabrication of polymer composites [1], [2]. The use of synthetic fibres had dominated the recent past of reinforcement industry; however the natural fibre reinforcement had gained much impetus to substitute this synthetic fibre in various applications [3]. The combination of natural fibres with polymer matrices from both non renewal (petroleum based) and renewal resources used to produce polymer composites that are competitive with synthetic composites is gaining attention over the last decade [4]. Biodegradable plastics and bio-based polymer products from renewal resources can form sustainable and eco-friendly products than can compete and capture current market which is dominated by petroleum based products [5]. Researchers have exploited both softwoods as well as hardwoods to extract the fibres for reinforcement in various composites [3]. For some developing countries, natural fibres are of vital economic importance: for example, cotton in some West African countries, jute in Bangladesh and sisal in Tanzania [1].
The countries where there is scarcity of forest resources, agricultural crops have been utilized for developments and research on polymer composites. Bamboo is one of the agricultural crops which can be exploited for the design and development of polymer composites [6]. Bamboo is found in abundance in Asia and South America. In many Asian countries bamboo has not been explored fully to its extent although it is considered as natural engineering material. This sustainable material has evolved as backbone for socio-economical status of society as it takes several months to grow up. Traditionally bamboo has been used in various living facility and tools, which owes to its high strength to its weight. This property is due to the longitudinal alignment of fibres. In practice, it is mandatory to fabricate the bamboo based composites in addition to the extraction of bamboo fibres in controlled way from bamboo trees [7], [8]. The bamboo fibres are naturally possessed with finer mechanical properties, but are brittle in nature as compared to other natural fibres due to the extra lignin content covering the bamboo fibres.
Presently bamboo is considered important plant fibre and has a great potential to be used in polymer composite industry. Its structural variation, mechanical properties, extraction of fibres, chemical modification, and thermal properties had made it versatile for the use in composite industry [9], [10]. On the basis of earlier reports, bamboo has 60% cellulose with high content of lignin and its microfibrillar angle is 2–10°, which is relatively small. This characteristic property has made bamboo fibre as fibre for reinforcement in variety of matrices [9], [11]. A variety of methods have been developed by researchers to extract the bamboo fibre for reinforcement of composites. Alkaline treatment was used as a tool for facilitation of bamboo fibre extraction and optimizes separation of bamboo fibres for preparation of bamboo fibre reinforced polymer composites [12], [13]. Researchers investigated the changes occurring in fine structure of bamboo fibre due to treatment with different concentration of alkali solution [14]. In an interesting study, researchers investigated effect of mercerization of bamboo fibres on mechanical and dynamical mechanical properties of bamboo composites [15], [16]. The common approach towards fabrication of composites from bamboo is to obtain better properties as compared to synthetic fibres. Bamboo fibres used as filler and twin-screw extruder was used for compounding of bamboo and biodegradable polymer for fabrication of bamboo reinforced polymer composites [9]. In another study, researchers used orthogonal bamboo fibre strip mats for fabrication of bamboo fibre reinforced epoxy and polyester composites by using hand lay-up technique [17], [18]. Dried bamboo fibres were used for preparation of short bamboo fibres reinforced epoxy composites and their chemical resistant and tensile properties with fibre length have been studied [19]. Researchers used bamboo belongs to species of Bambusa Paravariabilis, which grows abundantly in Asia for development of bamboo fibre reinforced polypropylene composites [20]. In an interesting study, bamboo which commonly grown in Singapore and can be abundantly throughout Southeast Asia was used together with E-glass fibres as reinforcement in the hybrid composites [21]. Researchers studied the effect of fibre length on the mechanical properties of polymer composites by using starch resin and short bamboo fibres [22].
A considerable effort has been made by researchers in good use of bamboo fibre as reinforcement in polymer composites. Bamboo fibres extracted from raw bamboo tress by steam explosion technique used for development of eco-composites and evaluated mechanical properties of bamboo fibre reinforced polymer composites [23]. Biodegradable and environment-friendly green composites developed by utilizing micro/nano-sized bamboo fibrils possessing moderate strength and stiffness [24]. Flexural properties of bio-based polymer composites made from bamboo and biodegradable resin were evaluated and it compared with kenaf composites [25]. They also calculated flexural modulus by Cox’s model that incorporates the effect of fibre compression were in good agreement with experimental results. Morphological and mechanical properties of bamboo flour filled HDPE based composites were investigated in respect of crystalline nature of maleated elastomer modifier, combined EPR-g-MA and PE-g-MA modifier systems and loading rate of bamboo flour in the presence of combined modifier [26]. Researchers investigated thermal properties of jute/bagasse hybrid composites and observed that thermal properties of hybrid composites increased by increasing char residue at 600 °C [27]. Polypropylene/polylactic acid/bamboo fibres blend composites were fabricated and morphological, and thermal properties of blend composites compared with neat polymers [28].
The presence of different functionalities particularly hydroxyl groups in the bamboo fibres would lead to the weak interfacial bonding between fibres and the relatively hydrophobic polymers, therefore researchers have tried to improve these properties by different interfacial treatments [29]. The strengthening effects on the bamboo fibres containing various matrices such as polystyrene, polyester and epoxy resins have been extensively studied. The economic value, light weight, high specific strength and non hazardous nature of bamboo fibres are among most attractive properties of this material which makes researchers to work in the direction of composite technology. Therefore, it can be revealed that bamboo fibre based composites have potential use in automotive industry, can replace the non-renewable, costly synthetic fibres in composite materials, particularly in the automotive industry and including household sectors. Presently an ecological threat has forced many countries to pass laws for using 95% recyclable materials in vehicles. The current era is the time for using natural fibres, particularly bamboo fibre based composites in daily lives. The extensive research from every field either engineering, biotechnological (genetic engineering), cultivation, etc. are trying to make one goal of utilizing these bamboo fibres in better way in composite Industry.
Section snippets
Socio-economic aspects of bamboo and bamboo fibre reinforced composites
The diversity of bamboo is itself reflected by its number of species, there are roughly 1000 species of bamboo found word wide. Bamboo grows very fast rather it is better to say extremely fast growing grass. Since, ancient time’s bamboo has been utilized in many Asian countries as well as South America for centuries. Bamboo can be considered an ecological viable substitute for commonly used wood in many ways. Bamboo attains maturity in 3 years as compared to wood which takes almost more than 20
Global distribution of bamboo
The bamboo is grown in various continents of the world, it has been divided accordingly; Asia–Pacific bamboo region, American bamboo region, African bamboo region and European and North American region (Table 2). The Asia–Pacific bamboo region is the largest bamboo growing area in the world. In Asian countries, bamboo is known by different names, In China it is known as “friend of people”, “wood of the poor” in India, “the brother” in Vietnam [33], [34]. FAO provided the data of bamboo
Eco bamboo fibre composites
Scientists have welcomed the move of imposing regulations for better and safer environment and had given a new direction to researchers towards generation of new ideas in eco-composite technology [47], [48], [49]. Eco-composite can be defined as composites with better environmental and ecological advantages over synthetic or conventional composites. Eco-composites can be fabricated from natural fibres or variety of natural polymers and polymer matrices. This field has gained enough popularity
Thermal characterization of bamboo fibre reinforced composites
Although a large number of reports based on characterization of plant natural fibre based composites, have been explored tremendously, but the reports on thermal characterization of fibres based composites, particularly, bamboo is quite scare. In this study, thermogravimetric analysis of alkali treated bamboo reinforced novolac resin exhibited better thermal stability as compared to untreated composites [65]. They explained that the better thermal stability was an outcome of interaction of
Bamboo fibre reinforced composites and design applications
In recent years the utilization of bamboo has been strengthened to exploit bamboo as non-wood renewable fibre. Agro-forestry has been boosted by this renewable fibre as bamboo attains full growth and maturity in one and 2 years, respectively. The fast growing and renewability of bamboo lead to an evolution in theoretical and applied research on bamboo based products, particularly in housing, furniture, packaging, transport, etc. (Fig. 13, Fig. 14). These composites have replaced traditional wood
Comparison of bamboo fibre reinforced composites with conventional composites
Bamboo fibres are well known for strong, stiff, inferior microfibrillar angle with the fibre axis and thicker cell wall and are considered as “nature’s glass fibre” [109]. The production of large quantity of synthetic fibre reinforced composite, e.g. glass/carbon fibre reinforced polymer composites, conventional composites and petroleum based plastics have posed serious threat to ecosystem. The disposition or recycling of glass fibre reinforced composites is not easy and safe for environment,
Conclusion
The exploitation of bamboo fibres in various applications has opened up new avenues for both academicians as well as industries to design a sustainable module for future use of bamboo fibres. Bamboo fibres have been extensively used in composite industries for socio-economic empowerment of peoples. The fabrication of bamboo fibre based composites using different matrices has developed cost effective and eco friendly biocomposites which directly affecting the market values of bamboo. To design
Future developments in bamboo fibre reinforced composites in advance technology
The sustainable tomorrow for future generation lies with the present industrial development towards eco efficiency of industrial products and their process of manufacturing. High performance, biodegradable materials and renewable plant materials can form new platform for sustainable and eco-efficient advance technology products and compete with synthetic/petroleum based products presently dominated in market which are diminishing natural petroleum feedstock. Natural fibres and biocomposites
Acknowledgements
The author H.P.S Abdul Khalil highly acknowledge and pay gratitude to the Department of Forest Products, Faculty of Forestry, Kampus IPB, Darmaga, Bogor Agricultural University, Bogor, 16001, West Java, Indonesia, for providing technical support and facilities during his short visit as a visiting professor.
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