Effects of nanoscale hydroxypropyl lignin on properties of soy protein plastics

ABSTRACT:The modified waterborne polyurethane (WPU) with enhanced mechanical properties has been prepared after introducing lignosulfonate calcium (LS). Meanwhile, the LS was associated with WPU component by chemical grafting and/or physical attraction and hence produced a star-like network with LS and its supramolecular complexes as center. Especially, when the LS content was 1.5 wt %, the strength and elongation of WPU/LS blends (WLS) simultaneously increased. At this time, the center of network was dominated by the single molecules of spherical LS. Thereafter, with the increase of LS content, the strength of WLS blends increased unceasingly up to 6.0-7.5 wt % of LS loading while the elongation gradually decreased. Because the LS tend to aggregate as supramolecular complexes spontaneously, the center of network was gradually replaced by the LS supramolecular complexes. The structural changes of WLS blends were characterized by FTIR, DSC, and DMA. The results suggested that the LS component was mostly fused with hard-segments of WPU component and hence induced the formation of physical interaction, importantly for hydrogen bonding, depending on the compulsive association of chemical grafting and the impulse of similar hydrophilicity between the hard-segment and LS.

Section: Introductionmentioning

confidence: 94%

Enhanced mechanical performances of waterborne polyurethane loaded with lignosulfonate and its supramolecular complexes

Cui

Xia

Chen

et al. 2007

“…25 Recently, the prominent reinforcing effects of nanometric scale and low loading content draw attentions to developing the soy-protein based bionanocomposite. Wei et al 29 and Chen et al 30 had enhanced the strength of soy protein plastics by virtue of the supramolecular nano-aggregates of hydroxylpropyl lignin. It was widely accepted that there existed the high affinity of clays to proteins and amino acids bearing neutral, positive, and even negative charges in soils.…”

Section: Introductionmentioning

confidence: 98%

Facile exfoliation of rectorite nanoplatelets in soy protein matrix and reinforced bionanocomposites thereof

Cui

Wei

et al. 2007

ABSTRACT:The rectorite (REC), a form of layered silicate, was facilely intercalated and even exfoliated in soy protein isolate (SPI) matrix. Furthermore, the reinforced biodegradable nanocomposite sheets were produced, in which the exfoliated REC lamellae plays a key role. After solution-mixing, XRD patterns showed that the REC lamellae were intercalated and even completely exfoliated for 4 wt % REC added, but the expanded gallery gradually became narrower with increasing REC content. FT-IR also verified the molecular-level associations between SPI molecules and REC lamellae by vibration variances of hydrogen bonding. The compression-molding further promoted intercalation and exfoliation, namely the 8 wt % REC can also be almost dispersed as exfoliated lamellae, while the interlayer of RECs also further separated for nanocomposites with higher REC content. TEM images visualized the transfer from exfoliation to intercalation and the decrease of interlayer distance with increasing REC content. The thicker and longer exfoliated REC lamellae resulted in high load and easy-to-yield of material. The maximum strength of nanocomposite sheets occurred at the addition of 12 wt % REC. Thereafter, the SPI chain can move more easily because of weak interaction between free negative-charge rich domain of SPI and REC surface in gallery, which did not favor enhancing mechanical performance.

“…In addition, the hydroxylpropyl lignin can spontaneously assemble as oblate supramolecular nanoaggregates in soy protein matrix to enhance the strength of materials. 13,14 A considerable attention has been concentrated on exploring the mechanisms of intercalation and exfoliation in academic opinions and developing highperformance and low-cost materials for meeting practical applications, owing to the great improvement of performances over pristine polymer, 15 such as reinforcing function, 16 reducing gas permeability, 17 enhancing thermal stability 18 and self-extinguishing fire-retardance, 19 and other interesting properties. Montmorillonite (MMT) is currently the most popular in the family of layered silicates, 20 and its nylon-based nanocomposite was taken as a representative example for the reinforcing effect.…”

Section: Introductionmentioning

confidence: 99%

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

Chang

Yang

Huang

et al. 2009

In this work, a nonconventional protein source of pea protein isolate (PPI) was filled with montmorillonite (MMT) and rectorite (REC) by solution intercalation respectively, and then the reinforced PPI-based nanocomposites were produced by hot press. The structure and interaction in the nanocomposites were investigated by FTIR, XRD, DSC, DMA, and pH and Zeta-potential tests whereas the reinforcing effect was verified by tensile test. Furthermore, the origin of enhancing mechanical performances and the effects of layered silicate structure were explored. Although the MMT with lower negative-charge surface and smaller apparent size of crude particles was easier to be exfoliated completely, the exfoliated REC nanoplatelets with more negative-charge could form stronger electrostatic interaction with positive-charge-rich domains of PPI molecules, and hence produced the highest strength in two series of nanocomposites. In this case, the newly formed hydrogen bonds and electrostatic interaction on the surface of silicate lamellas guaranteed the transferring of the stress to rigid layered silicates. The cooperative effect of newly formed physical interaction between layered silicates and PPI molecules as well as the spatial occupancy of intercalated agglomerates of layered silicates destroyed the original microphase structure of PPI matrix and cleaved the entanglements among PPI molecules. It was not in favor of enhancing the elongation and strength.