Structure and properties of starch nanocrystal‐reinforced soy protein plastics

Abstract

Pea starch nanocrystals (StNs) were incorporated into a soy protein isolate (SPI) matrix to produce a class of full‐biodegradable nanocomposites. The StN with low loading level (2 wt%) showed a predominant reinforcing function, resulting in an enhancement in strength and Young's modulus. This was attributed to uniform dispersion of StN in the amorphous region of the SPI matrix, as well as maintaining stress of the rigid StN and transfer of stress mediated by interfacial interaction between the active StN surface and the SPI matrix. As a result, the nanocomposite containing 2 wt% StN had the maximum strength and Young's modulus in all the materials. With an increase in StN content, the number and the size of StN domains simultaneously increased due to a strong self‐aggregation tendency of StN. It lowered the effective active StN surface for interaction with the SPI matrix and destroyed the ordered structure in the SPI matrix, resulting in a gradual decrease of strength and Young's modulus. The introduction of relatively hydrophilic StN did not cause an obvious decrease of water resistance for any of the nanocomposites. The water uptake behavior of all the nanocomposites similar to that of neat SPI material was attributed mainly to the strong interfacial interaction between the StN filler and the SPI matrix. POLYM. COMPOS., 2009. Published by the 2008 Society of Plastics Engineers

Effects of layered silicate structure on the mechanical properties and structures of protein‐based bionanocomposites

“…The resultant viscous solution (dark-gray for the REC/PPI blends and light-yellow for the MMT/PPI blends) was freeze-dried for 48 h to obtain the nanocomposites (gray REC/PPI powder or yellow MMT/PPI powder), which preserved the original complex state in solution. According to the REC content in solid powders of 2,4,8,12,16,20, and 24 wt %, the gray nanocomposite powders were coded as RP-2-P, RP-4-P, RP-8-P, RP-12-P, RP-16-P, RP-20-P, and RP-24-P, respectively. Meanwhile, the yellow nanocomposite powders containing 2,4,8,12,16,20, and 24 wt % MMT were coded as MP-2-P, MP-4-P, MP-8-P, MP-12-P, MP-16-P, MP-20-P, and MP-24-P, respectively.…”

“…6,7 The nano-clusters of aggregated spherical SiO 2 nanoparticles 8 and flexible carbon nanotubes 9 played a role on reinforcing and toughening soy protein plastics simultaneously. Meanwhile, the biodegradable polysaccharide nanoparticles, such as rod-like cellulose 10 and chitin 11 whiskers, and platelet-like starch nanocrystal, 12 were used to reinforce soy protein as well as enhancing water resistance. In addition, the hydroxylpropyl lignin can spontaneously assemble as oblate supramolecular nanoaggregates in soy protein matrix to enhance the strength of materials.…”

Cellulose-reinforced composites: From micro-to nanoscale

“…Starch nanocrystals (StNs) were used to reinforce a soy protein isolate (SPI) [43] or cassava starch [44] or waterborne polyurethane [45] matrices, in order to produce a class of full-biodegradable nanocomposites. Soy protein isolate was found to be efficiently reinforced even with very low StNs loading level (<2 wt%).…”

Effects of starch nanocrystal‐graft‐polycaprolactone on mechanical properties of waterborne polyurethane‐based nanocomposites

“…The starch nanocrystals (StNs) were prepared, as previously reported, 30 by H 2 SO 4 hydrolysis of native pea starch granules. Pea starch granules (14.69 g) were dispersed in 100 mL of 3.16M H 2 SO 4 , and stirred at 100 rpm for 5 days at 40 C. The resultant suspension was washed by successive centrifugation with distilled water until approximate neutrality.…”

“…These films were coded, according to the StN-g-PCL content in the blends, as WPU/StN-g-PCL(5), WPU/StN-g-PCL(10), WPU/ StN-g-PCL(15), WPU/StN-g-PCL (20), WPU/StN-g-PCL (25), and WPU/StN-g-PCL (30), where the numbers in brackets represent the theoretical weight percentage of StN-g-PCL in the films. The neat WPU film without StN-g-PCL was coded as WPU-F.…”