Effects of cellulose whiskers on properties of soy protein thermoplastics

Environmentally-friendly SPI/cellulose whisker composites were successfully prepared using a colloidal suspension of cellulose whiskers, to reinforce soy protein isolate (SPI) plastics. The cellulose whiskers, having an average length of 1.2 microm and diameter of 90 nm, respectively, were prepared from cotton linter pulp by hydrolyzing with sulfuric acid aqueous solution. The effects of the whisker content on the morphology and properties of the glycerol-plasticized SPI composites were investigated by scanning electron microscopy, dynamic mechanical thermal analysis, differential scanning calorimetry, ultraviolet-visible spectroscopy, water-resistivity testing and tensile testing. The results indicated that, with the addition of 0 to 30 wt.-% of cellulose whiskers, strong interactions occurred both between the whiskers and between the filler and the SPI matrix, reinforcing the composites and preserving their biodegradability. Both the tensile strength and Young's modulus of the SPI/cellulose whisker composites increased from 5.8 to 8.1 MPa and from 44.7 to 133.2 MPa, respectively, at a relative humidity of 43%, following an increase of the whisker content from 0 to 30 wt.-%. Furthermore, the incorporation of the cellulose whiskers into the SPI matrix led to an improvement in the water resistance for the SPI-based composites.     

Effects of calcium carbonate polymorph on the structure and properties of soy protein-based nanocomposites

Novel protein-based nanocomposites were well prepared by in vivo synthesis and co-precipitation of soy protein isolate (SPI) with calcium carbonate (CaCO3) in an aqueous solution. The resultant CaCO3 in the nanocomposites was identified as calcite- and aragonite-type, respectively. The morphology and structure of the CaCO3/SPI composites were investigated by means of wide-angle X-ray diffraction, Fourier transform infrared spectra, scanning electron microscopy, and high-resolution transmission electron microscopy. The results revealed that the polymorph and the size of CaCO3 in the nanocomposites were dependent on its content, pH, and the conformation of soy protein. At the content of more than 5%, CaCO3 was changed into calcite crystal with the preference of growing along (104) plane. However, at lower content of less than 5%, CaCO3 preferred to form aragonite in the composite as a result of the modulation by soy protein. The aragonite nanocrystals were arrayed in the direction of (111) plane and self-assembled along beta-sheet planes of soy protein polypeptides. The mechanical properties, thermal stability, and water resistance of the CaCO3/SPI nanocomposites were significantly improved as a result of the nanosized effects. Interestingly, the aragonite/SPI nanocomposite exhibited higher tensile strength (about 50 MPa) than that of calcite/SPI, owing to a good compatibility and strong interaction between aragonite and soy protein polypeptides. This work provided a simple pathway to develop the soy protein-based bio-hybrid materials with high mechanical strength and valuable information on their structure-properties relationship.     

Banana fiber-reinforced biodegradable soy protein composites

Banana fiber, a waste product of banana cultivation, has been used to prepare banana fiber reinforced soy protein composites. Alkali modified banana fibers were characterized in terms of density, denier and crystallinity index. Fourier transformed infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA) were also performed on the fibers. Soy protein composites were prepared by incorporating different volume fractions of alkali-treated and untreated fibers into soy protein isolate (SPI) with different amounts of glycerol (25%–50%) as plasticizer. Composites thus prepared were characterized in terms of mechanical properties, SEM and water resistance. The results indicate that at 0.3 volume fraction, tensile strength and modulus of alkali treated fiber reinforced soy protein composites increased to 82% and 963%, respectively, compared to soy protein film without fibers. Water resistance of the composites increased significantly with the addition of glutaraldehyde which acts as cross-linking agent. Biodegradability of the composites has also been tested in the contaminated environment and the composites were found to be 100% biodegradable.     

Properties and biodegradability of water-resistant soy protein/poly(?-caprolactone)/toluene-2,4-diisocyanate composites

Water-resistant composite plastics were prepared from soy protein isolate (SPI) or soy dreg (SD), poly(?-caprolactone) (PCL) and toluene-2,4-diisocyanate (TDI) as the compatibilizer by blending and one-step reactive extrusion (REX) followed by compression-molding. The structure and properties of the materials (SPI series and SD series) were investigated by Fourier transform infrared spectroscopy, scanning electron microscopy, differential scanning calorimetry, dynamic mechanical thermal analysis and tensile testing. The results indicated that SPI and SD series exhibited high water resistance and good tensile strength (14.8 MPa for SPI35 and 16.3 MPa for SD35). Moreover, the SD series sheets containing cellulose possessed higher tensile strength than those of SPI series when SD content was 30-35%, whereas the latter had a better biodegradability and water resistance. By burying the two series of sheets in soil and culturing them in a mineral salt medium containing microorganisms, both of them were almost completely degraded. This paper provides a convenient way to prepare new soy protein plastics with good biodegradability and water resistivity.     

Investigation into hemp fiber- and whisker-reinforced soy protein composites

Whiskers, designated as W, were prepared from hemp fibers. Both fibers and whiskers were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis. Scanning electron microscopy and transmission electron microscopy were used to evaluate the dimensions of the fibers and whiskers, respectively. By incorporating different weight fraction of the fibers and whiskers into soy protein isolate, we prepared two different composites designated as SC and SC-W, respectively. Thiodiglycol was used as a plasticizer for the preparation of composites. The SC and SC-W composites were characterized and compared in terms of mechanical properties, volume fraction of porosity, and water uptake. The results indicated that there was not much significant difference in the properties of the composites. In fact, mechanical properties of fiber-reinforced composites were higher than whisker-reinforced composites at optimum weight fractions. This study can give us the idea about the judicious use of fibers or whiskers as reinforcement materials.     

Natural rubber composites reinforced with basic magnesium oxysulfate whiskers: Processing and ultraviolet resistance/flame retardant properties

The Magnesium sulfate whiskers (MOSw) were first modified by Stearic acid or Si69, and Natural rubber (NR)/modified-MOSw composites were prepared by blending the modified-MOSw with natural rubber latex. By adding modified-MOS_W into NR, the mechanical properties, the anti-ultraviolet aging property, flammability, and thermal stability of composites were improved obviously. The mechanical properties, crosslink density and thermal stability of composites reach the highest value at 4 wt% Si69-MOS_W. The composite with MOS_W addtion had a higher retention rate after ultraviolet irradiation and the MOS_W could improve the anti-ultraviolet aging property of rubber matrix. The modified MOS_W can effectively improve the oxygen index and the flame retardant grade of rubber composites.     

Effect of soy protein isolate on the thermal, mechanical and morphological properties of poly (-caprolactone) and corn starch blends

The development of biodegradable polymers is considered to be a good alternative to decrease the volume of the plastic waste disposed into the environment every year. The use of natural polymers as raw materials to develop polymer blends and composites has increased the demand for renewable sources such as starch and soy protein.In this work, the authors prepared and characterized the thermal, mechanical and morphological properties of blends based on poly (-caprolactone) and modified corn starch, with added soy protein isolate (SPI) and sorbitol. All samples were processed by extrusion in a single-screw extruder and hot pressing. It was observed that the addition of modified corn starch and SPI were responsible for the reduction of thermal and mechanical properties of the materials, compared to pristine PCL. However, with increasing amounts of SPI and the reduction of starch incorporated into the samples, their properties tend to recover. The insertion of soy protein isolate in the formulations was done with the aim of balancing the C/N ratio of the blend, which plays a key role in the biodegradation process of these materials.     

Structure and properties of the nanocomposite films of chitosan reinforced with cellulose whiskers

Bio‐based nanocomposite films were successfully developed using cellulose whiskers as the reinforcing phase and chitosan as the matrix. Cellulose whiskers, with the lengths of 400 ± 92 nm and diameters of 24 ± 7.5 nm on average, were prepared by hydrolyzing cotton linter with sulfuric acid solution. The effects of whisker content on the structure, morphology and properties of the nanocomposite films were characterized by SEM, XRD, FTIR, UV‐vis spectroscopy, DMA, TG, tensile testing, and swelling experiment. The results indicated that the nanocomposites exhibited good miscibility, and strong interactions occurred between the whiskers and the matrix. With increasing whisker content from 0 to 15–20 wt %, the tensile strength of the composite films in dry and wet states increased from 85 to 120 MPa and 9.9 to 17.3 MPa, respectively. Furthermore, the nanocomposite films displayed excellent thermal stability and water resistance with the incorporation of cellulose whiskers. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1069–1077, 2009     

聚苯乙炔基苯基硅氧硼烷树脂及其复合材料的性能

将双(N-间乙炔基苯基邻苯二甲酰亚胺)醚(DAIE)和双酚A型氰酸酯(CE)分别加到聚苯乙炔基苯基硅氧硼烷(PSOB)和三苯乙炔基苯基硅烷(PTPES)混合体系中进行改性,制得两种纤维增强复合材料PSOB-PTPES-DAIE和PSOB-PTPES-CE.研究了固化后树脂的热稳定性能、力学性能、介电性能和耐水性能.结果...     

Thermal properties of polyfurfuryl alcohol absorbed/adsorbed on arylated soy protein films

In this study, polyfurfuryl alcohol was absorbed/adsorbed on soy protein isolate films by immersing the SPI films in acid-catalysed furfuryl alcohol solution for 60 h followed by complete curing at 145–150 °C for 2 h. PFA absorbed/adsorbed soy protein films designated as SPI-PFA were then arylated in the presence of 0.5% (w/v) 2,2-diphenyl-2-hydroxyethanoic acid for 4 h to fabricate arylated soy protein films designated as SPI-PFA-Ar. The incorporation of PFA and introduction of aromatic backbone through arylation is revealed from Fourier transform infrared study. Thermal studies of SPI, SPI-PFA and SPI-PFA-Ar were carried out by thermogravimetric analysis, differential scanning calorimetry and dynamic mechanical thermal analysis. In addition, mechanical properties, surface morphology and water uptake of all the three different types of the films were evaluated. Results indicated that PFA absorbed/adsorbed arylated soy protein films showed higher thermal stability than native SPI films.     

Obtaining nanocomposites of polyamide 6 and cellulose whiskers via extrusion and injection molding

Nanocomposites of polyamides with cellulose whiskers are difficult to obtain by conventional processing of extrusion and injection molding because of the low thermal stability of the cellulosic nanostructures and the relatively high processing temperature of polyamides, which is higher than the temperature of thermal degradation of cellulose whiskers. Thus, in this study cellulose whiskers were coated with polyamide 6 (PA6) in order to increase their thermal stability and prevent the formation of agglomerates. This coating on cellulose whiskers allows their application to obtain nanocomposites with polyamides, whose processing temperatures are relatively high, around 250 °C. Cellulose whiskers (CWs) were obtained from cotton fibers by acid hydrolysis. The freeze-dried CWs were coated with PA6 by dispersing them in formic acid; PA6 was solubilized in this suspension. The cellulose-coated whiskers (CCWs) were characterized by X-ray diffraction, differential scanning calorimetry (DSC), thermogravimetry (TG), scanning electron microscopy (SEM-FEG) and infrared spectroscopy. SEM-FEG and TG results showed that the PA6 coating on CWs prevented high agglomeration of dried CWs and promoted an increase in their thermal stability from 180 to 280 °C, allowing the use of CCWs to obtain nanocomposites with PA6 using conventional processing routes, such as extrusion and injection molding, at appropriate processing temperatures. In this way, 1 wt% CCWs was used to prepare nanocomposites with PA6. The PA6 + 1CW nanocomposites were compared to neat PA6 without CWs. The samples were characterized by tensile tests and DSC, and the results showed that the PA6 coating on CWs was effective in raising the thermal stability of CWs, improving the dispersion of CWs in the matrix of PA6, resulting in a 45 % increase in the elastic modulus of the nanocomposite with only 1 wt% of coated cellulose whiskers in comparison to neat PA6.     

Electrochemical capacitance study of cellulose-manganese dioxide nano-composite

In this study, cellulose-manganese dioxide nano-composites were synthesized and their electrochemical behavior studied as electrode in an electrochemical supercapacitor (ECS). The morphology of composites were investigated by scanning electron microscopy (SEM). Thermal gravimetric analysis (TGA) was used to determine the thermal stability and water content of the composites. The electrochemical capacitance of the composites is studied by cyclic voltammetry (CV) in Na₂SO₄ electrolyte (0.5 M) at room temperature. The results show that the capacitance of the composites are strongly affected by the nano-structure, structural continuity, thermal stability and surface/structural water of manganese dioxide. A high specific capacitance of 171 F/g was obtained for cellulose-manganese dioxide nano-composite which has higher structural continuity, lower water content and better thermal stability.     

PREPARATION AND CHARACTERIZATION OF SOY PROTEIN ISOLATE(SPI)/MONTMORILLONITE(MMT) BIONANOCOMPOSITES

 The bionanocomposites of soy protein isolate (SPI)/montmorillonite (MMT) have been prepared successfully via simple melt mixing, in which MMT was used as nanofiller and glycerol was used as plasticizer. Their structures and properties were characterized with X-ray diffraction (XRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), thermogravimetric analysis and tensile testing. XRD、TEM and SEM results indicated that the MMT layers could be easily intercalated by the SPI matrix even by simple melt processing. The exfoliated MMT layers were randomly dispersed in the protein matrix as MMT content was low (less than 5 wt%), an incomplete exfoliation was evident from SEM results, and some primary particles were observed as the MMT content was high (from 5 wt% to 9 wt%). A significant improvement of the mechanical strength and thermal stability of SPI/MMT nanocomposites has been achieved. Our work suggests that simple melt processing is an efficient way to prepare SPI/MMT nanocomposites with exfoliated structure.     

Performance of high-temperature thermosetting polyimide composites modified with thermoplastic polyimide

The preparation of polyimide (PI) resin with high heat resistance and toughness is a significant challenge. In this study, thermoplastic PI (TPI) was used to toughen thermosetting PIs, and toughened PI (TPI/PI) blends were prepared. The modified PI resin system exhibited good thermal stability, excellent heat resistance, and high toughness. The results indicated that the TPI/PI blends maintained the curing behavior and characteristics of the PI oligomer. The T_g of the cured TPI/PI blend exceeded 395 °C, and the T_5% values were in the range of 533–563 °C, suggesting excellent thermal stability and heat resistance. The maximum impact strength was increased by 46% compared with that of pure PI, indicating the excellent toughening effect of the TPI. Carbon fiber-reinforced PI composites were prepared using the toughening system as a matrix. The compression-after-impact values of the carbon fiber-reinforced PI composites were up to 190 MPa, indicating the excellent toughness of the materials.     

超细全硫化粉末丁腈橡胶对聚氯乙烯性能的影响

制备了PVC/超细全硫化粉末丁腈橡胶(NBR-UFPR)二元、PVC/NBR-UFPR/纳米CaCO3三元复合材料,研究了3种NBR-UFPR(平均粒径分别为150nm、90nm和70nm)对硬质PVC性能的影响.测试结果表明,3种NBR-UFPR均可同时提高硬质PVC的热稳定性、耐热性和韧性.透射电镜(TEM)照片显示,3种NBR-UFPR均能以单个粒子均匀分散在PVC基体中,NBR-UFPR与PVC相间的界面积大于传统的PVC/弹性体共混物.PVC/NBR-UFPR/纳米CaCO3三元复合材料具有更高的热稳定性、耐热性和韧性,TEM照片显示,在三元复合材料中,分散相粒子间的平均距离进一步减小.     

Viscoelastic properties of ionic polymer composites reinforced by soy protein isolate

Both linear and nonlinear viscoelastic properties of ionic polymer composites reinforced by soy protein isolate (SPI) were studied. Viscoelastic properties were related to the aggregate structure of fillers. The aggregate structure of SPI is consisted of submicron size of globule protein particles that form an open aggregate structure. SPI and carbon black (CB) aggregates characterized by scanning electron microscope and particle size analyzer indicate that CB aggregates have a smaller primary particle and aggregate size than SPI aggregates, but the SPI composites have a slightly greater elastic modulus in the linear viscoelastic region than the CB composites. The composite containing 3–40 wt % of SPI has a transition in the shear elastic modulus between 6 and 8 vol % filler, indicating a percolation threshold. CB composites also showed a modulus transition at <6 vol %. The change of fractional free volume with filler concentration as estimated from WLF fit of frequency shift factor also supports the existence of a percolation threshold. Nonlinear viscoelastic properties of filler, matrix, and composites suggested that the filler‐immobilized rubber network generated a G′ maximum in the modulus‐strain curves and the SPI formed a stronger filler network than the CB in these composites. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 3503–3518, 2005     

Synthesis and characterization of sulfonated polyimide membranes for direct methanol fuel cell

The sulfonated polyimide (SPI) membranes for direct methanol fuel cell (DMFC) were synthesized with 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (BTDA), 2,2′-benzidinedisulfonic acid (BDSA), 4,4′-oxydianiline (ODA) through classical two-step methods: (1) preparation of sulfonated poly(amic acid) (SPAA) precursors with different sulfonation levels by controlling the molar ratio of BDSA to ODA, and (2) thermal imidization of the SPAA films. The chemical structure and the imidization from SPAA membranes were characterized by FT-IR with temperature, and the sulfonation levels were determined by elemental analysis. The thermal stability of the membranes was also characterized by TGA. From water uptake and small angle X-ray scattering (SAXS) experiments for different sulfonation levels, it was found that the number of water clusters in SPI membranes increased as the water uptake of membranes increased, but the size of water cluster was not changed with the sulfonation levels. The proton conductivity and the methanol permeability of SPI membrane showed a sudden leap like a percolation phenomenon around 35 mol% of sulfonation level. The SPI membranes exhibited relatively high proton conductivity and extremely low methanol permeability, and showed the feasibility of suitable polymer electrolyte membranes (PEM) for DMFC.     

DSC study on the thermal properties of soybean protein isolates/corn starch mixture

The use of soybean protein isolates (SPI) and corn starch (CS) for the manufacturing of textured protein by thermo-mechanical means requires a characterization of their thermal properties. SPI and CS mixtures were examined at starch mass fractions from 0 (pure SPI) to 100 (pure CS). The blends were determined by means of differential scanning calorimetry, with water content of 30, 50, and 70 % and heating rate of 5 and 10 °C min^?1 over 20 to 130 °C. The results obtained showed that protein in the blend increased the onset (T _o) and peak (T _p) temperatures of the starch gelatinization, while starch in the blend decreased the ΔH and ΔT_1/2 of the protein. T _o , T _p, and ΔT_1/2 of SPI and CS decreased significantly with the increase of water content. T _p and ΔT_1/2 of SPI and CS had a marked increase with an increase of heating rate from 5 to 10 °C min^?1. These results suggested that there was no chemical reaction between SPI and CS when they were heated from 20 to 130 °C. SPI in the blend restricted the CS gelatinization, while the presence of CS protected the SPI from denaturation. The increasing water content did promote thermal transition of the mixture. Higher heating rate leads to higher transition temperature.     

磺化聚芳醚砜/磺化聚酰亚胺复合质子交换膜的制备与性能研究

利用溶液浇铸法制备了一系列双磺化型磺化聚芳醚砜/磺化聚酰亚胺(SPAES/SPI)复合质子交换膜.扫描电子显微镜(SEM)结果显示复合膜不存在明显的相分离,表明二者具有很好的相容性.由于SPI的引入,复合膜在甲醇中稳定性较纯SPAES具有大幅的提高,比Nafion112低得多的甲醇吸收率表明了这些复合膜具有比后者更低的甲醇透过率.复合膜显示了与单组分膜相类似的高温分解稳定性,磺酸基团的分解温度达到了290℃以上.复合膜显示出远高于纯SPAES膜的尺寸稳定性能,在130℃高温中200h处理后,所有的复合膜均保持了高的机械性能,而此时纯SPAES膜已经溶解于水中.而且由于两种磺化聚合物间的复合,复合膜维持了较高的IEC水平,显示了较高的质子导电率,在80%相对湿度时的质子导电率与Nafion112相近,而在水中的质子导电率均高于Nafion112.     

Effects of flower-like ZnO nanowhiskers on the mechanical, thermal and antibacterial properties of waterborne polyurethane

A novel waterborne polyurethane/flower-like ZnO nanowhiskers (WPU/f-ZnO) composite with different f-ZnO content (0-4.0 wt%) was synthesized by an in-situ copolymerization process. The f-ZnO consisting of uniform nanorods was prepared via a simple hydrothermal method. In order to disperse and incorporate f-ZnO into WPU matrix, f-ZnO was modified with γ-aminopropyltriethoxysilane. Morphology of f-ZnO in WPU matrix was characterized by scanning electron microscope. The properties of WPU/f-ZnO composites such as mechanical strength, thermal stability as well as water swelling were strongly influenced by the f-ZnO contents. It was demonstrated that appropriate amount of f-ZnO with good dispersion in the WPU matrix significantly improved the performance of the composites. The mechanical property was enhanced with an increase of f-ZnO content up to the optimum content (1 wt%) and then declined. Incorporation of f-ZnO enhanced the water resistance of the composites remarkably. It was amazing to observe that the thermal degradation temperatures of the composites initially decreased significantly and then leveled off with content increase of f-ZnO, which was different from the results of other WPU composite systems reported. Antibacterial activity of WPU/f-ZnO composite films against Escherichia coli and Staphylococcus aureus was also tested. The results revealed that the antibacterial activity enhanced with the increasing f-ZnO content, and the best antibacterial activity was obtained at the loading level of 4.0 wt% f-ZnO.