Biocomposite mechanical properties

Keywords Natural fiber, biocomposites, mechanical properties, environmental effect... 

The results of mechanical properties (presented later in this section) showed that up to 20 phr, the biofillers showed superior strength and elongation behavior than CB, cellulose being the best. After 30 phr the mechanical properties of biocomposites deteriorated because of the poor compatibility of hydrophilic biopolymers with hydrophobic natural rubber(results not shown). While increasing quantity of CB in composites leads to constant increase in the mechanical properties. Scanning electron micrographs revealed presence of polymer-filler adhesion in case of biocomposites at 20 phr. 

The results of the mechanical properties can be explained on the basis of morphology. The scanning electron micrographs (SEM) of fractured samples of biocomposites at 40 phr loading are shown in figure. 3. It can be seen that all the bionanofillers are well dispersed into polymer matrix without much agglomeration. This is due to the better compatibility between the modified polysaccharides nanoparticles and the NR matrix (Fig. 4A and B). While in case of unmodified polysaccharides nanoparticles the reduction in size compensates for the hydrophilic nature (Fig. 3C and D). In case of CB composites (Fig. 3E) relatively coarse, two-phase morphology is seen. 

Amaral, M., Lopes, M.A., Silva, R.F., Santos, J.D., Densification route and mechanical properties of Si3N4-bioglass biocomposites, Biomaterials, 23, 2002, 857-862. 

The interactions between the whiskers and the matrix are very significant The high form ratio of the nanoparticles (50-200) and the high specific surface area ( 170 m. g ) enable us to obtain major phenomena at the interphase. Indeed, in relation to traditional biocomposites based on cellulose fibers or microfibrils, the overall behavior of whisker-based materials is primarily linked to the interface/interphase between the matrix and the nanofiller, which controls the properties and overall performances of the material (mechanical properties, permeability, etc.). 

In nature, fibrous biopolymers have long been used in the reinforcement of extracellular biocomposites, inspiring the reproduction of this technology using native CNs as filler in a range of host polymer matrixes. Due to the highly crystalline nature of the cellulose nanoparticles, they possess attractive mechanical properties, such as an axial Young s Modulus of around 140 GPa, which is dependent on cellulose crystallinity and axial ratio [36]. When... 

Torres, F.G., Arroyo, O.H., Gomez, C. Processing and mechanical properties of natural fiber reinforced thermoplastic starch biocomposites. J. thermoplast. compos, mater. 20,... 

Ghanbarzadeh, B., Oromiehi, A.R. Biodegradable biocomposite films based on whey protein and zein barrier, mechanical properties and AFM analysis. Int. J. Biol. Macromol. 43, 209-215 (2008)... 

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. 

The demand for better fuel efficiency based on the strict governmental regulations on safety and emission has led to the wide application of composites and plastics in the automotive industry in the place of the traditionally used steels [32]. Thermoplastic materials reinforced with natural fibers have reported to have excellent mechanical properties, recycling properties, etc. [33-36]. Several natural and biorenewable fibers such as wheat, isora, soybean, kenaf, straw, jute, and sisal are used in the fiber/plastic composite industry, and the use of namral fibers as reinforcements for composite has attracted many industries [37, 38]. Compared to polymer resin, polymer biocomposites that are reinforced with natural fibers have many applications due to its ease of processing, comparatively lower cost, and excellent mechanical properties [39]. For more than a decade, European car manufacturers and suppliers have been using natural fiber-based composites with thermoplastic and thermoset matrices. These biocomposites and bionanocomposites... 

Biomaterials have been defined as materials which are compatible with living systems. In order to be biocompatible with host tissues, the surface of an implant must posses suitable chemical, physical (surface morphology) and biological properties. Over the last 30 years, various biomaterials and their applications, as well as the applications of biopolymers and their biocomposites for medical applications have been reported. These materials can be classified into natural and synthetic biopolymers. Synthetic biopolymers are cheaper and possess better mechanical properties. However, because of the low biocompatibility of synthetic biopolymers compared with that of natural biopolymers, such as polysaccharides, lipids, and proteins, attention has turned towards natural biopolymers. On the other hand, natural biopolymers usually have weak mechanical properties, and therefore much effort has been made to improve them by blending with some filler. 

Both treatments result in superior mechanical properties in comparison to the untreated fiber reinforced composites. The deflection temperature of the PLA laminated composites is significantly higher than that of the resin. So, standard PLA resins are very useful in the manufacture of kenaf fiber reinforced laminated biocomposites (29). 

Shen, L., Yang, H., Ying, J., Qiao, F, and Peng, M. (2009) Preparation and mechanical properties of carbon fiber reinforced hydroxyapatite/polylactide biocomposites. J. Mater. Sci. - Mater. Med., 20 (11), 2259-2265. 

Hyun SL, Donghwan C (2008) Effect of natural fiber surface treatments on the interfacial and mechanical properties of henequen/polypropylene biocomposites. Macromol Res 16 411 17... 

Yang HS, Wolcott MP, Kim HS, Kim S, Kim HI (2007) Effect of different compatibilizing agents on the mechanical properties of lignocellulosic material filled polyethylene biocomposites. Compos Struct 79 369-375... 

Figure 17.6 shows the tensile mechanical properties of biocomposites based on different fillers (LCPq i, LCFo o.i, and LCFo.i-i) with different content (from 0 to 30 wt%). Stress-strain evolutions show that PBAT is at room temperature a ductile material with a high elongation at break (ei,), more than 200%. This is consistent with Tg and Tf values. 

Lu Y, Weng L, Cao X (2005) Biocomposites of plasticized starch reinforced with cellulose crystallites fromcottonseed linter. Macromol Biosci 5 1101-1107 Lu Y, Weng L, Cao X (2006) Morphological, thermal and mechanical properties of ramie crystallites-reinforced plasticized starch biocomposites. Carbohydr Polym 63 198-204 Malainine ME, Mahrouz M, Dufi esne A (2005) Thermoplastic nanocomposites based on cellulose microfibrils from Opuntia ficus-indica parenchyma cell. Compos Sci Technol 65 1520-1526 Mangalam AP, Simonsen J, Benight AS (2009) Cellulose/DNA hybrid nanomaterials. Biomacromolecules 10 497-504... 

Chapters 15-18 focus on the weathering/mechanical study of lignocellulosic fiber-reinforced polymer composites. The effect of different environmental conditions on the physico-chemical and mechanical properties of the polymer composites is discussed in detail in these chapters. Chapter 15 mainly focuses on the effect of weathering conditions on the properties of lignocellulosic polymer composites. Most of the focus of this chapter is the effect of UV radiation on different properties of composites. Chapter 16 describes the effect of layering pattern on the physical, mechanical and acoustic properties of luffa/coir fiber-reinforced epoxy novolac hybrid composites, and Chapter 17 summarizes the fracture mechanism of wood plastic composites. Chapter 18 focuses on the mechanical behavior of biocomposites xmder different environmental conditions. 

Y. Lu, L. Weng, and X. Cao, Morphological, thermal and mechanical properties of ramie crystallites—Reinforced plasticized starch biocomposites. Carbohydr. Polym. 63, 198-204 (2006). 

M. Khalid, A. Salmiaton, T.G. Chuah, C.T. Ratnam, and S.Y.T. Choong, Effect of MAPP and TMPTA as compatibilizer on the mechanical properties of cellulose and oil palm fiber empty fruit bunch-polypropylene biocomposites. Compos. Interfaces 15, 251-262 (2008)... 

S. Shinoj, R. Visvanathan, S. Panigrahi, and N. Varadharaju, Dynamic mechanical properties of oil palm fibre (OPF)-linear low density polyethylene (LLDPE) biocomposites and study of fibre-matrix interactions. Biosyst. Eng. 109,99-107 (2011). 

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