Chitin whiskers fillers

Dufresne et al. studied stress vs strain curves (nominal data) for the chitin whiskers/unvulcanized NR evaporated composites, shown in Figure 14.12."" The polymeric matrix is in the rubbery state and its elasticity from entropic origin is ascribed to the presence of numerous entanglements due to high molecular weight chains. They further observed that the incorporation of anhydride and isocyanate modified chitin whiskers into NR lead to composite materials with improved mechanical properties. The study of the morphology of these nanocomposites leads to the conclusion that the various chemical treatments improve the adhesion between the filler and the matrix (Figure 14.13). However in some cases there is loss of performance, which could be due to the partial or total destruction of the three-dimensional network of chitin whiskers assumed to be present in the unmodified composites. 

The reinforcing effect of starch nanocrystals was compared to the one of other fillers for NR pubhshed in the literature such as clays, organoclays, carbon black, fly ash and chitin whiskers. 

Chitin nanowhiskers obtained from crab shells were incorporated into SPI to improve the thermomechanical properties and to decrease water sensitivity of the SPI (Lu et al. 2004). A relatively uniform distribution of the chitin whisker in the SPI matrix can be observed when the chitin content is lower than 15 wt%. With an increase of chitin whiskers in the SPI matrix from 0 to 30 wt%, enhanced thermal, mechanical, and water resistance of the soy protein composite was observed. The water diffusion coefficients (D) of the nanocomposites decrease from 2.56 x 10 to 1.23 X 10 ° cm s . The tensile strength and Young s modulus of the composites increase from 3.3 to 8.4 MPa and from 26.4 to 158 MPa with increasing chitin content from 0 to 20 wt%, whereas the elongation at break of the filled composites decreases from 205 to 29 %. The improvement in all of the properties of these novel SPI/chitin whisker nanocomposites may be ascribed to three-dimensional networks of intermolecular hydrogen bonding interactions between filler and filler and between filler and SPI matrix. 

For example, Lu et al. [195] developed environmentally friendly thermoplastic nanocomposites using a colloidal suspension of chitin whiskers as a filler to reinforce SPI plastics. Chitin whiskers prepared from commercial chitin by acid hydrolysis were added to SPI. The authors reported that SPI/chitin whisker... 

Abstract Nature is gifted with several nanomaterials which could be obtained from different animal and plant sources. Cellulose, chitin and starch are abundant, natural, renewable and biodegradable polymers. By intelligent processing techniques they could be used as classical nano reinforcing fillers in polymers i.e., composites. They are often called whiskers. 

Fibrous fillers for biomedical PLA-based FRPs include carbon and inorganic fibres [406], PLLA (i.e. self-reinforcement) [407,408], poly(p-dioxane) fibre [409], chitin [410], biodegradable fibre (e.g. bioactive glass, chitosan fibre, polyester amides) [411], hydroxyapatite fibre [412], hydroxyapatite whiskers [413], halloysite (Al2Si205(0H)4) nanotubes [414] and the fibre from different tissue types of Picea sitchensis [415],... 

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