Starch nanocrystal

Angellier-Coussy,H.,Putaux, J.-L.,Molina-Boisseau,S.,Dufresne,A.,Bertoft,E., Perez,S. (2008). The molecular structure of waxy maize starch nanocrystals. Carbohydr. Res. (In press). 

Angellier, H., Choisnard, L., Molina-Boisseau, S., Ozil, P, Dufresne, A. (2004). Optimization of the preparation of aqueous suspensions of waxy maize starch nanocrystals using a response surface methodology. Biomacmmolecules, 5, 1545-1551. 

Song, S., Wang, C., Pan, Z., Wang, X. (2008). Preparation and characterization of amphiphilic starch nanocrystals. Journal of Applied Polymer Science, 107,418-422. 

ANG 06] Angeller H., Molina-Boisseau S., Dole P., etal, Thermoplastic starch-waxy maize starch nanocrystals nanocomposites . Biomacromolecules, vol. 7, no. 2, pp. 531-539,2006. 

Angellier, H., Boisseau, S.M., Lebrun, L., Dufresne, A. Processing and structural properties of waxy maize starch nanocrystals reinforced natural rubber. J. Macromolecules. 38, 3783-3792 (2005a)... 

Kristo, E., Biliaderis, C.G. Physical properties of starch nanocrystal-reinforced pullulan films. Caibohydr. Polym. 68, 146-158 (2007)... 

The reinforcing effect of starch nanocrystals was attributed to strong filler/matrix interactions due to the hydrogen bonding. The decrease of the permeability suggests that the nanocrystals were well dispersed, with few filler/filler interactions. 

The incorporation of platelet-Uke starch nanocrystals into natural rubber may remarkably enhance the barrier performances, e.g., of water vapor and oxygen (16,17). 

The preparation, properties and applications of polysaccharide nanocrystals in advanced functional nanomaterials have been reviewed (27). Cellulose based nanocrystals decompose and undergo a carbonization reaction over 250°C, whereas starch nanocrystals... 

TPS Waxy-maize/Glycerol/ Water cast film Reseach" starch nanocrystals [151]... 

Cellulose, Composites, Nanocomposites, Natural fibres, Lignocellulosic fibres. Cellulose whiskers, Chitin Whiskers, Starch nanocrystals... 

Compared to cellulose or chitin, the morphology of constitutive nanocrystals obtained from starch is completely different. Figure 19.12 shows a TEM obtained from a dilute suspension of waxy maize starch nanocrystals. They consist of 5-7 nm thick platelet-like particles with a length ranging 20-40 nm and a width in the range of 15-30 nm. The detailed investigation on the stmcture of these platelet-like nanoparticles was reported [36]. 

The barrier properties of starch nanocrystals/natural rubber nanocomposites were also investigated [39]. For these systems, the water vapour transmission rate, the diffusion coefficient of oxygen, the permeability coefficient of oxygen and its solubility, were measured. It was observed that the permeabiUty to water vapour, as well as to oxygen, decreased when starch nanocrystals wctc added These effects were ascribed to the platelet-like morphology of the nanocrystals. 

Starch occurs as a flour-like white powder, which is insoluble in cold water after its extraction from plants. Native starches contain between 15 and 45% of crystalline material. Starch crystallite, starch nanocrystal, microcrystalline starch and hydrolysed starch all refer to the crystalline part of starch, which are obtained by different extents of acidic hydrolysis. We will focus on starch nanocrystals. Cellulose nanocrystals are 100% crystalline materials, but starch nanocrystals consist of 45% crystalline portion. 

Waxy starch nanocrystal (wt% ) Tensile strength (MPa) Elongation at break (Vo) Ref. 

NR composites and nanocomposites can be fabricated by three main techniques, namely latex compounding, solution mixing and melt blending. A variety of nanofillers, such as carbon black, silica, carbon nanotubes, graphene, calcium carbonate, organomodified clay, reclaimed rubber powder, recycled poly(ethylene terephthalate) powder, cellulose whiskers, starch nanocrystals, etc. have been used to reinforce NR composites and nanocomposites over the past two decades. In this chapter, we discuss the preparation and properties of NR composites and nanocomposites from the viewpoint of nanofillers. We divide nanofillers into four different types conventional fillers, natural fillers, metal or compound fillers and hybrid fillers, and the following discussion is based on this classification. 

Preparation of starch nanocrystal-reinforced NR nanocomposites is often by the solution mixing method. The general steps are depicted as follows the first step is preparation of starch nanocrystals. Starch nanocrystals were usually extracted from natural starch crops (such as maize,cassava, potato, wheat, eZc.) by hydrolysis in the presence of strong acids (such as sulfuric acid or hydrochloric acid).The second step is the mixing of the starch nanocrystal... 

To allow the processing of composite materials from an organic solvent instead of aqueous suspensions and to achieve maximum interaction and adhesion between the filler and the matrix, the surface chemical modification of starch nanocrystals was carried out. Contact angle measurements have shown that the surface chemical modification of waxy maize starch nanocrystals with isocyanate and anhydride functions enhanced the non-polar nature of original starch nanocrystals. 

Some NR-based nanocomposites with bio-based nanoreinforcements like chi-tin whiskers, starch nanocrystals, cellulose whiskers. A lot of work on bionanocomposites of NR has been reported by Alain Dufresne and coworkers.But most of these studies use latex blending technique without vulcanization, for the bionanocomposites preparation. There are less reports available on vulcanized rubber-based bionanocomposites prepared by master batch processing and two-roll mill mixing, which have the potential to be adapted for commercial use. ... 

Waxy maize starch nanocrystals appeared to be an effective reinforcing agent for NR at temperatures higher than the glass transition temperature of the... 

Nominal (a) elongation at break, (b) strength, (c) nominal strength vs nominal elongation at break (the starch nanocrystal contents are indicated in panel) and (d) tensile modulus for waxy starch nanocrystals/ NR nanocomposite films vs starch content. 

Figure 14.15 Typical nominal stress vi nominal strain curves of waxy maize starch nanocrystals/NR nanocomposite films. The starch nanocrystal contents are indicated in the figure.

Figure 14.16 SEM of the fractured surfaces of (a) unfilled NR, NR filled with (b) 5 and (c, d) 30 wt% of starch nanocrystals, NR filled with (e) 5 and (f) 30 wt% of ASA-modified particles, and NR filled with (g) 5 and (h) 30 wt% of Pl-modified starch nanoparticles.

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