Biocomposites structural applications

The mechanical performance required of biocomposites is dependent on specific structural applications. Crude inferences can be made by comparing properties of materials that these biocomposites are intended to substitute. Mechanical data and/or allowable design values of wood and engineered wood products were used to evaluate potential applications of hemp fabric/cellulose acetate composites and hemp fabric/poly (hydroxybutyrate) composites (Table 13.2). From the comparisons, it can be inferred that these biocomposites, despite not passing the design values of wood structural material, can potentially substitute engineered wood products (of the same size) such as plywood and oriented strand boards to partially capture existing markets as crates, pallets, and formwork [38]. 

The experiences made have shown that biocomposites can be excellently processed to make structural material. The weight-related mechanical properties make it possible to strive for application areas that are still dominated by glass fibre-reinforced plastics. At this time, limitations must be accepted in areas with extreme environmental conditions. Main target groups therefore are, for example, panelling elements in automobile and freight car manufacturing, the furniture industry and the entire market of the sports and leisure industry. 

It is important to emphasize that many natural tissues are essentially composed of nanoscale biopolymers or biocomposites with hierarchical architectures. Therefore, by mimicking the structure and property of their natural counterparts, synthetic nanopoiymers and nanocomposites are very likely to enhance/regulate the functions of specific cells or tissues. This principle has been demonstrated by the success of bioinspired polymers and composites in both clinical practice and in laboratory research. In particular, bone is the hierarchical tissue that has inspired a myriad of biomimetic materials, devices, and systems for decades. This chapter focuses on this well-developed area of biomimetic or bioinspired nanopoiymers and nanocomposites for bone substitution and regeneration, especially those with high potentials for clinical applications in the near future. 

Most of the previous research on natural fibre composites has focused on reinforcements such as flax, hemp, sisal and jute, and thermoplastic and thermoset matrices. Some of these composites have been produced using matrices made of derivatives from cellulose, starch and lactic acid to develop fully biodegradable composites or biocomposites [52]. The emerging diversity of applications of natural fibre composites has seen the production of sandwich structures based on natural fibre composite skins (see Fig. 23.10). 

The current knowledge related to the structure and chemistry of cellulose, and the development of innovative cellulose derivatives for different applications (coatings, films, membranes, building materials, pharmaceuticals, foodstuffs), as well as the new perspectives, including environmentally-friendly cellulose fiber technologies, bacterial cellulose biomaterials, in-vitro syntheses of cellulose, and cellulose-based biocomposites were highlighted in several important works [30-34]. 

Lungu, A. Albu, M.G. Trandafir, V. (2007). New biocomposite matrices structures based on collagen and synthetic polymers designed for medical applications. Materiale Plastice, Vol.44, No.4, pp. 273-277, ISSN 0025-5289 Ma, P.X. Elisseeff, J. (Eds.). (2005). Scaffolding in Tissue Engineering, Taylor and Francis, ISBN 9781574445213, Florida, United States of America Martinko, B. (1987). Determination of Thermal Stability of Polymers for Water Base Muds. 

Alternative routes, due to environmental awareness and increasing interest in sustainable material concepts, have led to the development of bio- and green composites for structural composite applications, the so-called all-polymer composites or self-reinforced polymer composites . These new materials promise to overcome the critical problem of fiber-matrix adhesion in biocomposites by using chemically similar or identical cellulose materials for both matrix and reinforcement and are designated as all-cellulose composites [39, 40]. 

---