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Abstract Spinnability and rheological properties of soy protein are studied for potential application in food products. It has been considered impossible to spin globular proteins due to the difficulty in extending the molecules to achieve high degree of intermolecular entanglement. In order to improve the spinnability of globular proteins, other polymers were incorporated. This paper shows a good spinnability of 100% globular soy protein. In this work, aqueous urea/reductant system is selected for efficient stretch and entanglement globular soy proteins for fiber spinning. In this system, hydrogen bonds, hydrophobic and electrostatic interaction were disrupted by urea, while disulfide bonds were cleaved by reductants. Moreover, the backbones of globular soy proteins were not severely destroyed, rendering the stretched globular protein spinnable and the spun fibers mechanically robust. Relationship between rheological properties and spinnability of globular soy protein solutions is quantified. In order to be spinnable, globular soy proteins should be highly stretched, and thus entangled with preserved backbones. Graphical abstract Image 1 Highlights • Globular soy protein could be spun to fibers after proper dissolution. • A solvent system selected for efficient intermolecular entanglement of soy protein. • Relationship quantified between rheological property and spinnability of soy protein. • Soy protein fibers are potential candidates for various food applications. [ABSTRACT FROM AUTHOR]

• Keratin films were reinforced by interfacially-compatible nano-cysteine particles. • Cysteine particles with smaller sizes showed better reinforcing effects. • The keratin composite films were tough, pliant and stable in high humidity. • Keratin composite films demonstrated good biocompatibility in vitro study. Keratin films with wet stability and strength suitable for biomedical applications were developed via reinforcement with submicron cysteine particles for improved interfaces. Keratin products regenerated from wool or human hair were widely investigated as wound dressing and tissue engineering scaffolds for their satisfactory biomedical properties. However, regenerated keratin scaffolds usually did not have good mechanical properties, and also could not stand humid or wet biological environment due to poor moisture stability. Reinforcements for keratin materials were usually polysaccharides or synthetic polymers, and thus usually had non-ideal interfacial properties due to limited compatibility. In this research, submicron cystine particles were employed to reinforce keratin films for their high compatibility with keratin and bio-safety. Transition of primary and secondary structures of keratin due to matrix-reinforcement interaction was analyzed. The keratin films showed unprecedented pliancy, good tensile properties under humid conditions and biocompatibility, and thus had good potential for biomedical engineering applications. [ABSTRACT FROM AUTHOR]

Graphical abstract Without pretreatment, chemically substituted cellulose has a fast hydrolysis rate for biomass conversion. Highlights • The substituted cellulose has a high hydrolysis rate. • The substituted cellulose does not need pretreatments for bioconversion. • Hydrolysis rate is quantitatively correlated to structures of substituents. • Dyed cotton has a comparable hydrolysis rate to other catalytic methods. Abstract This paper investigates the accelerated acidic hydrolysis of cellulose by its substituents for potential biomass conversion. Insufficient pretreatments and slow cellulose hydrolysis are major obstacles that impede efficient hydrolysis of cellulose. Substituted cellulose, such as dyed cotton, has large availability. It is susceptible to acidic hydrolysis and can be used for biomass conversion without any pretreatments. To understand the mechanism of accelerated hydrolysis of cellulose by its substituents is a prerequisite for cellulosic biomass conversion with high efficiency. Substituents with different charge properties were synthesized and their interactions with oxocarbenium ions were studied based on Density Functional Theory. Results indicate that hydrolysis rate is affected by field effect from substituents. Such field effect is dominated by amounts of negative charges on substituents and distance between negatively charged groups and oxocarbenium. Hydrolysis rate of dye-substituted cotton is higher than or comparable to that applied with other catalytic approaches. [ABSTRACT FROM AUTHOR]

One-hundred percent stereo-complexation in poly( l-lactide) (PLLA)/poly( d-lactide) (PDLA) fibers with non-equivalent molecular weights could be achieved via thermal treatment. Stereo-complexed polylactide (sc-PLA) fibers exhibited excellent hydrolysis resistance and thermal resistance. Till now, preparation of sc-PLA fibers with satisfactory qualities required both PLLA and PDLA with equivalently high molecular weights. Moreover, the high-molecular-weight PDLAs are expensive, restricting industrial-scale production and applications of sc-PLA products. In this study, equal-weight mixtures of low-molecular-weight PDLA (L-PDLA) and high-molecular-weight PLLA (H-PLLA) were melt spun into sc-PLA fibers and then completely stereo-complexed via thermal treatment. The hydrolysis resistance of L3/D1 fibers [PLLA ( M = 3.0 × 10)/PDLA ( M = 1.0 × 10)] was similar to that of L3/D3 fibers [PLLA ( M = 3.0 × 10)/PDLA ( M = 3.2 × 10)], but much higher than that of L3 fibers [PLLA ( M = 3.0 × 10)]. Melting temperature and softening temperature of L3/D1 fibers (223 and 126 °C) were also similar to those of L3/D3 fibers (224 and 131 °C), but higher than that of L3 fibers (172 and 72 °C). Utilizing H-PLLA and L-PDLA to prepare sc-PLA fibers with excellent performance is conducive to the wide industrial application of sc-PLA. [ABSTRACT FROM AUTHOR]

A clean and cost-effective method for 100% stereo-complexation in polylactide (PLA) fibers with molecular weight (MW) as high as 6 × 10 5 demonstrates good potential for industrial-scale continuous manufacture. Polylactide, a widely recognized biodegradable and renewable biopolymer, has a negligible share of plastic markets due to its poor hydrolytic and thermal resistance. Stereo-complexation is effective in overcoming these challenges. However, current stereo-complexation approaches usually require solvents and/or external nucleation reagents, and are expensive and complicated. Moreover, high-MW PLAs favored for developing durable products are difficult to be stereo-complexed. In this research, enantiomeric PLAs both with MW up to 6 × 10 5 were completely stereo-complexed via a facile thermal treatment on pilot-scale devices. Neither solvent nor nucleation agent was used. For poly(L-lactide) (PLLA) fibers with MW of 6 × 10 5 , percentage retention of MW and percentage retention of tensile strength after hydrolysis under simulated textile dyeing condition increased from 39% to 93% and from 20% to 89%, respectively, after complete stereo-complexation. The melting point, softening point and percentage retention of MW after hydrolysis of stereo-complexed PLA (sc-PLA) fibers were up to 51 °C, up to 59 °C and up to 183% higher than that of PLLA fibers with the same MW, respectively. The mechanism of thorough stereo-complexation in high-MW PLA fibers was proposed and verified. It is promising to use this approach to broaden industrial applications of renewable and degradable biopolymers for sustainable development of material industries. [ABSTRACT FROM AUTHOR]

In this research, compression‐molded composites were developed from discarded polypropylene (PP) carpets and showed good mechanical properties, water stability and acoustic property. Compared to jute/PP composites, the composites from PP carpets had 14%, 20%, and 40% higher flexural strength, impact resistance, and elastic modulus, respectively. In addition, with 58.3% and 14.5% higher sound absorption and water stability than jute/PP composites, the composites from carpets demonstrated good potential for industrial applications and could promote sustainability of material industries. POLYM. COMPOS., 39:595–605, 2018. © 2016 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

A facile and clean technology for stereo-complexation of polylactides (PLAs) shows potential to be readily incorporated into continuous industrial processes for manufacture of films, fibers and other plastic products. Using this approach, complete stereo-complexation of high-molecular-weight PLAs could be achieved via simple thermal treatment, rendering the production of durable PLA commodities inexpensive and industrially scalable. Currently, due to their high susceptibility to water and heat, PLA products have restricted industrial applications, and cannot compete with their petroleum-derived counterparts. Stereo-complexation of poly( l -lactic acid) (PLLA) and poly( d -lactic acid) (PDLA) could effectively decrease water and heat sensitivity of common PLLA products. However, many stereo-complexation processes required harmful solvents or nucleating agents, and thus, were costly, complicated, and had low potential for short-term industrialization. Moreover, complete stereo-complexation was mostly achieved for PLAs with weight-average molecular weight lower than 1 × 10 5 . In this research, PLLA and PDLA both with viscosity-average molecular weight of 3 × 10 5 were completely stereo-complexed (sc) via simple thermal treatment. Comparing to PLLA fibers, sc-PLA fibers had softening points 60 °C higher, and their thermal and hydrolytic stability significantly enhanced. Relationship among temperature of thermal treatment, degree of stereo-complexation and performance properties of sc-PLA fibers were also established. This clean technology makes possible industrial-scale production of commercializable biobased plastics. [ABSTRACT FROM AUTHOR]

High-efficiency and recyclable three-dimensional bioadsorbents were prepared by incorporating cellulose nanocrystal (CNC) as reinforcements in keratin sponge matrix to remove dyes from aqueous solution. Adsorption performance of dyes by CNC-reinforced keratin bioadsorbent was improved significantly as a result of adding CNC as filler. Batch adsorption results showed that the adsorption capacities for Reactive Black 5 and Direct Red 80 by the bioadsorbent were 1201 and 1070 mg g −1 , respectively. The isotherms and kinetics for adsorption of both dyes on bioadsorbent followed the Langmuir isotherm model and pseudo-second order model, respectively. Desorption and regeneration experiments showed that the removal efficiencies of the bioadsorbent for both dyes could remain above 80% at the fifth recycling cycles. Moreover, the bioadsorbent possessed excellent packed-bed column operation performance. Those results suggested that the adsorbent could be considered as a high-performance and promising candidate for dye wastewater treatment. [ABSTRACT FROM AUTHOR]

Fully biodegradable textile sizes with satisfactory performance properties were developed from soy protein with controlled hydrolysis and dis-entanglement to tackle the intractable environmental issues associated with the non-biodegradable polyvinyl alcohol (PVA) in textile effluents. PVA derived from petroleum is the primary sizing agent due to its excellent sizing performance on polyester-containing yarns, especially in increasingly prevailing high-speed weaving. However, due to the poor biodegradability, PVA causes serious environmental pollution, and thus, should be substituted with more environmentally friendly polymers. Soy protein treated with high amount of triethanolamine was found with acceptable sizing properties. However, triethanolamine is also non-biodegradable and originated from petroleum, therefore, is not an ideal additive. In this research, soy sizes were developed from soy protein treated with glycerol, the biodegradable triol that could also be obtained from soy. The soy sizes had good film properties, adhesion to polyester and abrasion resistance close to PVA, rendering them qualified for sizing applications. Regarding desizing, consumption of water and energy for removal of soy size could be remarkably decreased, comparing to removal of PVA. Moreover, with satisfactory degradability, the wastewater containing soy sizes was readily dischargeable after treated in activated sludge for two days. In summary, the fully biodegradable soy sizes had potential to substitute PVA for sustainable textile processing. [ABSTRACT FROM AUTHOR]

For the first time, rheological behavior of soy protein isolate (SPI) solution with high concentration for fibers and films was studied. The results showed that SPI could be readily dissolved in urea/sodium sulfite aqueous system, and the SPI solution is suitable for wet spinning and film casting. The effects of concentration, temperature, and shear rates on the rheological properties of SPI solution were studied. Viscosity of SPI solution decreases with increasing temperature, which is good for the preparation of solution with high concentration and regenerated SPI fibers/films with good properties. All solution samples exhibited thixotropic behavior, which were different from traditional polymer solution for wet spinning and film casting process. Both in forward and backward measurements were carried out by the Power Law model. Under constant shear rates (80-160 s −1 ), 18 wt% SPI solution was chosen to study the dependence of viscosity on time. Second order structural kinetic model, Weltman model, first-order stress decay models with zero and none-zero equilibrium stress values were used to fit the rheological data. Among the four models, Weltman model is more appropriate to fit the thixotropic data. [ABSTRACT FROM AUTHOR]

All-green textile sizes with satisfactory weaving performance and biodegradability were developed from soy protein and glycerol, two major byproducts from soy-based biodiesel production. Polyvinyl alcohol has long dominated textile sizing chemical market due to its excellent sizing performance, despite its non-biodegradability. Efforts have been devoted to replace polyvinyl alcohol for a more sustainable textile industry. Recently, substitute size developed from soy protein after using high amount of petro-based triethanolamine showed acceptable sizing properties. However, triethanolamine was not an eco-friendly additive, due to its petroleum origin and non-biodegradability. In this research, glycerol was used to plasticize soy protein to develop all-green soy size. Glycerol interrupted hydrogen bonds in the soy globulin, allowing them to extend in the films. Resultantly, the soy size films possessed high stretchability and work of rupture. Lab-scale experiments and industrial weaving proved that the all-green soy size had similar or better weaving performance and remarkably better degradability, comparing to polyvinyl alcohol and triethanolamine plasticized soy protein size. For the first time, a possible logarithmic relationship was found between work of rupture of the size film and relative weaving efficiency. [ABSTRACT FROM AUTHOR]

Graft polymerization of acrylic acid endowed soy protein films with good tensile properties and water solubility without sacrificing biodegradability. In this research, soy protein was grafted with acrylic acid and cast into biodegradable films as substitutes of non-biodegradable Poly(vinyl alcohol) (PVA) films. The grafted soy protein films had 318%, 114%, 60% and 9% higher tensile strength, elongation, dissolving rate and transmittance, compared to ungrafted ones, respectively. Acrylic acid grafting provided soy protein films with biodegradability, flexibility, and adhesion to yarns substantially higher than PVA, while water solubility and abrasion resistance similar to PVA, leading to high potential applications of the grafted soy proteins in the fields of water soluble packaging films and slashing to substitute PVA. [ABSTRACT FROM AUTHOR]

Soymeal, which contains natural plasticizer and tackifier, has been used to fabricate biodegradable and low-cost warp sizes, with potential for replacing non-biodegradable polyvinyl alcohol (PVA) sizes for large-quantity industrial applications. Warp sizes from soyprotein isolates (SPI) have been reported as a potential substitute for PVA sizes, which contribute to high chemical oxygen demand in textile effluents and cause serious water pollution. However, sizes from SPI are high in cost and need additional plasticizers to overcome brittleness of films. In this research, the developed low-cost soymeal sizes contain soyprotein as majority and saccharides/saponified-oil from soymeal as minorities. Comparing to films from triethanolamine-plasticized SPI sizes, the soymeal size had about 30.1, 25.2 and 8.3% higher film flexibility, adhesion to yarns and abrasion resistance, respectively. Saccharides in soymeal and saponified oil formed during size extraction functioned as plant-based additives with capability of improving adhesion of protein sizing pastes to cotton and/or polyester yarns and increasing elongation of protein-based size films. Successful utilization of soymeal in textile sizing will lead to its large-quantity application, resulting in high value addition to agricultural byproducts and profound impact on soybean industry and textile industry. [ABSTRACT FROM AUTHOR]

In this work, kinetics of substitution accelerated cellulose hydrolysis with multiple reaction stages was investigated to lay foundation for mechanism study and molecular design of substituting compounds. High-efficiency hydrolysis of cellulose is critical for cellulose-based bioethanol production. It is known that, substitution could substantially decrease activation energy and increase reaction rate of acidic hydrolysis of glycosidic bonds in cellulose. However, reaction kinetics and mechanism of the accelerated hydrolysis were not fully revealed. In this research, it was proved that substitution therefore accelerated hydrolysis only occurred in amorphous regions of cellulose fibers, and was a process with multiple reaction stages. With molar ratio of substitution less than 1%, the overall hydrolysis rate could be increased for around 10 times. We also quantified the relationship between the hydrolysis rate of individual reaction stage and its major influences, including molar ratio of substitution, activation energy of acidic hydrolysis, pH and temperature. [ABSTRACT FROM AUTHOR]

For the first time, mechanism and kinetics of citric acid crosslinking of protein in neutral aqueous condition under low temperature are reported. Crosslinking was a conventional method to improve properties of protein products to replace petroleum-derived polymers. However, current crosslinking methods were toxic, expensive or required harsh conditions. Non-toxic carboxylic acid could effectively enhance wet performance properties of multiple protein products under mild conditions, which were critical for preserving the activities during immobilization of enzymes. In this study, more than one carboxyl groups in one citric acid molecule were found capable of reacting with protein in aqueous medium at pH 6.8 under 50 and 75 °C, verifying occurrence of crosslinking. The pseudo second-order reaction had activation energy as low as 24.956 kJ mol −1 , indicating its easy occurrence. Mild crosslinking using citric acid might provide alternative to accelerate low-cost and efficient enzyme immobilization as well as industrial utilization of protein-based products. [ABSTRACT FROM AUTHOR]

For the first time, mechanical properties of cross-linked protein products were quantitatively correlated with cross-linking degrees and molecular structures of polycarboxylic acids. Non-toxic polycarboxylic acids could effectively improve performance properties of multiple protein products via cross-linking. However, the reaction mechanism and relationship between reaction and performance properties remained unclear. In this study, the cross-linking reaction between gliadin, and polycarboxylic acids was verified. Natural logarithm relationship was found between the cross-linking degree and tensile strength of protein films. The polycarboxylic acids with more carboxyl groups and shorter backbones could more effectively increase the tensile strength of gliadin films. [ABSTRACT FROM AUTHOR]

Oxidized sucrose, an un-traditional biobased crosslinker, was proved as effective as glutaraldehyde in improving water stability of ultrafine fibrous proteins without causing cytotoxicity. Proteins from agricultural byproducts, such as zein, are abundantly available for production of industrial and medical products, but are restricted by their poor water stability and wet properties. An effective and safe crosslinking method became indispensable for protein-based materials, especially biomaterials. Fibrous basic units with sub-micron scale were critical for biomaterials to resemble native extracellular matrices (ECMs) structurally. In this research, sucrose was oxidized into polar polyaldehydes to crosslink ultrafine fibrous scaffolds from corn protein. The control groups were crosslinked with glutaraldehyde, a known highly effective crosslinker with considerable toxicity. With similar improvement in water stability, the oxidized sucrose crosslinked scaffolds showed much better cytocompatibility than the glutaraldehyde crosslinked ones via in vitro study with preosteoblast cells. [ABSTRACT FROM AUTHOR]

For the first time, pure protein fibers with good mechanical properties were obtained from waste wool after effective de-crosslinking and disentanglement of the highly crosslinked keratin. Every year, more than 1.6 billion pounds of wool keratin-based materials were discarded. Effort has been devoted to convert the keratin resources into high value-added products, especially fibers. In 1940s, pure keratin fibers had been developed from feathers. However, after trying the method, we found the results were not repeatable and did not find any other successful repetition. So far, no effective dissolution and spinning methods have been developed to obtain pure keratin fibers with potential for real applications. In this research, keratin with preserved backbones after de-crosslinking was obtained. Subsequently, surfactant endowed the keratin with satisfactory stretchability for fiber spinning. Fibers of 20 μm with good tensile strength were successfully developed. The technology could be applied onto other highly crosslinked proteins, including feather keratin from poultry industry, sorghum protein and soy protein in bioenergy co-products for production of various industrial products. [ABSTRACT FROM AUTHOR]

Intrinsically water-stable scaffoldscomposed of ultrafine keratin fibers oriented randomly and evenlyin three dimensions were electrospun for cartilage tissue engineering.Keratin has been recognized as a biomaterial that could substantiallysupport the growth and development of multiple cell lines. Besides,three-dimensional (3D) ultrafine fibrous structures were preferredin tissue engineering due to their structural similarity to nativeextracellular matrices in soft tissues. Recently, we have developeda nontraditional approach to developing 3D fibrous scaffolds fromalcohol-soluble corn protein, zein, and verified their structuraladvantages in tissue engineering. However, keratin with highly cross-linkedmolecular structures could not be readily dissolved in common solventsfor fiber spinning, which required the remarkable drawability of solution.So far, 3D fibrous scaffolds from pure keratin for biomedical applicationshave not been reported. In this research, the highly cross-linkedkeratin from chicken feathers was de-cross-linked and disentangledinto linear and aligned molecules with preserved molecular weights,forming highly stretchable spinning dope. The solution was readilyelectrospun into scaffolds with ultrafine keratin fibers orientedrandomly in three dimensions. Due to the highly cross-linked molecularstructures, keratin scaffolds showed intrinsic water stability. Adipose-derivedmesenchymal stem cells could penetrate much deeper, proliferate, andchondrogenically differentiate remarkably better on the 3D keratinscaffolds than on 2D PLA fibrous scaffolds, 3D soy protein fibrousscaffolds, or 3D commercial nonfibrous scaffolds. In summary, theelectrospun 3D ultrafine fibrous scaffolds from keratin could be promisingcandidates for cartilage tissue engineering. [ABSTRACT FROM AUTHOR]

Abstract: In this study, biodegradable hollow zein nanoparticles with diameters less than 100 nm were developed to remove reactive dyes from simulated post-dyeing wastewater with remarkably high efficiency. Reactive dyes are widely used to color cellulosic materials, such as cotton and rayon. Wastewater from reactive dyeing process contains up to 50% dye and electrolytes with concentrations up to 100 g L−1. Current methods to remove reactive dyes from wastewater are suffering from low adsorption capacities or low biodegradability of the sorbents. In this research, biodegradable zein nanoparticles showed high adsorption capacities for dyes. Hollow zein nanoparticles showed higher adsorption for Reactive Blue 19 than solid structures, and the adsorption amount increased as temperature decreased, pH decreased or initial dye concentration increased. At pH 6.5 and pH 9.0, increasing electrolyte concentration could improve dye adsorption significantly. Under simulated post-dyeing condition with 50.0 g L−1 salt and pH 9.0, maximum adsorption of 1016.0 mg dye per gram zein nanoparticles could be obtained. The adsorption capacity was much higher than that of various biodegradable adsorbents developed to remove reactive dye. It is suggested that the hollow zein nanoparticles are good candidates to remove reactive dye immediately after dyeing process. [Copyright &y& Elsevier]

In this work, novel electrospun scaffolds with fibersorientedrandomly and evenly in three dimensions (3D) including in the thicknessdirection were developed based on the principle of electrostatic repulsion.This unique structure is different from most electrospun scaffoldswith fibers oriented mainly in one direction. The structure of novel3D scaffolds could more closely mimic the 3D randomly oriented fibrousarchitectures in many native extracellular matrices (ECMs). The cellculture results of this study indicated that, instead of becomingflattened cells when cultured in conventional electrospun scaffolds,the cells cultured on novel 3D scaffolds could develop into stereoscopictopographies, which highly simulated in vivo 3D cellular morphologiesand are believed to be of vital importance for cells to function anddifferentiate appropriately. Also, due to the randomly oriented fibrousstructure, improvement of nearly 5 times in cell proliferation couldbe observed when comparing our 3D scaffolds with 2D counterparts after7 days of cell culture, while most currently reported 3D scaffoldsonly showed 1.5- to 2.5-fold improvement for the similar comparison.One mechanism of this fabrication process has also been proposed andshowed that the rapid delivery of electrons on the fibers was thecrucial factor for formation of 3D architectures. [ABSTRACT FROM AUTHOR]

• Keratin filaments were developed from poultry feather wastes. • Dual-functional dithiols endow filaments with higher ductility than feathers. • Filament regeneration potentially creates more than 100-billion-dollar revenue. • Poultry wastes can be substantially reduced. Technology for the transformation of waste feathers to quality regenerated filaments has been developed. Regardless of superior properties of natural keratin materials, previously developed regenerated materials from keratin had tensile properties much lower than their natural counterparts due to backbone hydrolysis and inefficient reconstruction of disulfide crosslinkages. In this work, tough keratin filaments have been regenerated from white duck feathers via efficient restoration of disulfide crosslinkages using a dithiol reducing agent. Dithiol substantially reserves free thiol groups in the extraction and formed lengthy intermolecular crosslinkages in regenerated keratin filaments. Due to the high degree of intermolecular reconstruction of disulfide bonds and formation of lengthy crosslinkages via dithiol chain-extension, the keratin filaments exhibited considerable improvements in mechanical properties, especially for ductility and water stability. The tenacity and elongation at break were 160.7 MPa and 14%, respectively. The filaments retained about 80% of the tenacity of natural feathers at either dry or wet conditions and demonstrated stretchability 150% higher than natural feathers. The fiber regeneration technology makes it possible to substitute primary fiber sources by renewable poultry feathers. Successful filament substitution or addition can bring more than 88-billion-dollar revenue. The technology not only contributes to a sustainable fiber and poultry industry but adds substantial values to poultry feathers. [ABSTRACT FROM AUTHOR]

A urea-cysteine based system is developed to extract densely crosslinked sorghum proteins from sorghum distillers grains with high efficiency and quality. Due to the high crosslinking degrees, sorghum proteins are expected to possess better tensile properties and aqueous stabilities than common proteins, thus become a promising candidate to replace the unsustainable petroleum products. However, due to the long-standing difficulty in dissolution of densely crosslinked proteins, to extract sorghum proteins with high efficiency and quality for satisfactory properties in end products has not been achieved by previous methods In this paper, a urea-cysteine based system is used to replace the most widely used ethanol based system. The urea-cysteine based system endows sorghum proteins with high purity and yield, which are 14% and 42% higher than those from the ethanol based system. Based on amine and thiol group analysis, the urea-cysteine based system provides sorghum proteins with preserved peptide backbones, full breakage of disulfide bonds for linear structures and sufficient thiol groups for re-oxidation. Due to such unique structures and thus regular arrangement of protein molecules during film casting, sorghum protein films from the urea-cysteine based system have crystallinity 21% higher than those from the ethanol based system. Tensile properties and water-vapor-barrier properties of sorghum protein films are improved by 27% and 28% compared to the ethanol based system. Sorghum protein films derived from sorghum distillers grains are first reported and their tensile properties are better than those of all sorghum protein films developed previously. Quantified effects of preservation of protein peptide backbones and recovery of disulfide bonds on tensile strength are also compared. With the unique structures, sorghum proteins from the urea-cysteine based system have great potential to achieve excellent properties in various applications, such as films and fibers, which account for a total market share of over $100 billion worldwide. [ABSTRACT FROM AUTHOR]

Using chitosan as pretreatment agent, the dyeing properties of peanut skin extracts (PSE) to flax fabrics were improved. Flax fabrics have excellent comfort property and are loved by many people. However, flax is different to dye, especially with natural dye. In this research, chitosan was used to pretreat flax fabrics and PSE was used to dye the pretreated flax fabric. The optimal conditions of the chitosan pretreatment and dyeing conditions of PSE were investigated according to the K/S value of the dyed flax fabrics. Comparing the original flax fabric, the chitosan pretreated flax fabric significantly improved the absorption to PSE, and the dyed fabrics had an increased K/S value from 0.9 to 3.9, and had good color fastnesses. The main chemical constitution in PSE such as catechin, chitosan, and cellulose of flax fabrics may form hydrogen bond and ionic bond. Chitosan pretreated and dyed flax fabrics had a stronger ability to UV resistance and scavenging free radicals. The fluorescence intensity of the dyed flax fabrics was improved while it was decreased after chitosan pretreatment. Chitosan pretreatment combined PSE dyeing can be used to develop functional flax textiles without using metallic mordants. [ABSTRACT FROM AUTHOR]

Without additional matrix or reinforcement, compression molded composites from waste polypropylene (PP) carpets/nylon (PA) carpets or PP carpets/polyester (PET) carpets have higher mechanical properties and sound absorption than traditional jute/PP composites. Large amount of carpets have been discarded every year, leading to waste of petro-based materials and serious environmental pollution. Fabrication of composites from discarded carpets via compression molding could save petroleum resources and alleviate environmental pressure. In this research, the compression molded composites from waste PP/PA carpets or PP/PET carpets showed good mechanical properties, sound absorption and water stability. Compared to the jute/PP composites, nylon 6,6 (PA66)/PP carpet composites had 37% and 9% higher flexural strength and impact resistance, as well as 45% and 10% higher sound absorption and water stability, indicating their potential for transportation and construction industries. [ABSTRACT FROM AUTHOR]

Discarded carpets with high amount of petroleum-based fibers are usually disposed in landfills, leading to waste of high value petro-polymers and environmental pollution. A novel method to reuse nylon carpet targeting environmental protection and material saving was developed. Recent studies showed that melt blended nylon carpet composites by screw extruder had low mechanical properties and disqualified carpet composites in transportation and construction industries. In this research, compression molded composites from discarded nylon 6/nylon 6,6 carpets had good sound absorption, mechanical properties and water stability. As compared with jute/PP composites, the compression molded composites from nylon 6/nylon 6,6 carpets had up to 40%, 59%, 124% and 32%, higher sound absorption, flexural strength, elastic modulus and impact resistance, respectively. Unshredded nylon 6,6 carpet yarns and styrene-butadiene-rubber/calcium-carbonate binders in carpets reinforced nylon 6 and polypropylene, and thus made the composites strong. Styrene-butadiene-rubber particles and multiple interfaces in the multi-component composites endowed compression molded nylon 6/nylon 6,6 carpet composites with good sound absorption. Developing compression molded carpet composites with good mechanical properties and sound absorption provides a new method of reusing carpets. [ABSTRACT FROM AUTHOR]

Cellulosic fibers with high aspect ratio have been firstly obtained from cornhusks via controlled swelling in organic solvent and simultaneous tetramethylammonium hydroxide (TMAOH) post treatment within restricted depth. Cornhusks, with around 42% cellulose content, are a copious and inexpensive source for natural fibers. However, cornhusk fibers at 20 tex obtained via small-molecule alkaline extraction were too coarse for textile applications. Continuous NaOH treatment would result in fine fibers but with length of about 0.5–1.5 mm, too short for textile use. In this research, post treatment using TMAOH and under controlled swelling significantly reduced fineness of cornhusk fibers from 21.3 ± 2.88 to 5.72 ± 0.21 tex. Fiber length was reduced from 105.47 ± 10.03 to 47.2 ± 27.4 mm. The cornhusk fibers had more oriented microstructures and cellulose content increased to 84.47%. Besides, cornhusk fibers had similar tenacity, longer elongation, and lower modulus compared to cotton and linen, which endowed them with durability and flexibility. [ABSTRACT FROM AUTHOR]

A novel strategy adaptive to 3D printing of stereo-complexed polylactide matrix for simultaneous toughness and stiffness was designed. Stereo-complexation is a potent way to enhance both aqueous stability and heat resistance of polylactide, but also aggravates brittleness problem of polylactide. Though poly(butyleneadipate- co -terephthalate) elastomer with epoxidized compatibilizer improved stiffness and toughness of common polylactide, their effectiveness on mechanical and crystallization properties of stereo-complexed polylactide remained unknown. More importantly, incorporation of above techniques into 3D printing kept a fundamental challenge. Both stereo-complexation of polylactide and co valent coupling of polylactide and poly(butyleneadipate-co-terephthalate) by epoxidized compatibilizer are easy to occur when preparing the filaments for printing, impeding the following 3D printing procedure. The hypothesis for this research is that controlled hierarchical crystallization and reaction in three thermal processes could ensure simultaneous toughness and stiffness, and complete stereo-complexation in polylactide matrices. Reinforcing effects of a selected epoxidized compatibilizer, POSS (epoxy)8 , on crystallinities, thermal properties, mechanical properties and morphologies were systematically studied. Such a strategy not only removed the obstacles in incorporating stereo-complexation and coupling techniques of polylactide into 3D printing, but also revealed the mechanism to produce high-performance 3D printed polylactide matrix via hierarchical crystallization and reaction. • A novel strategy adaptive to 3D printing of stereo-complexed PLA was designed. • Hierarchical crystallization and reaction ensured feasibility of the strategy. • Improvement in composite ductility coincides with increase in strength. • Reinforcing effects of epoxidized POSS on PLA properties were systematically studied. • Complete stereo-complexation was achieved in 3D printed PLA matrices. [ABSTRACT FROM AUTHOR]

Cellulose nanocrystals (CNCs), acrylamide (AAm) and poly (ethylene glycol) (PEG) can be co-assembled and photopolymerized into responsive, patterned photonic films with chiral nematic (N*) structures. Here, we report stimuli-responsive CNC/AAm/ PEG composite films (CFs) for use in humidity sensing. With the increase of AAm content, the CFs had an increased helical pitch and showed a red shift. With the adding of PEG, the CFs can quickly capture or release water molecules in air, which resulted in the changes of the helical pitch in N* structures and the structural color. After photopolymerization, the elastic modulus, hardness by nanomechanical testing and tensile strength of polymer films (PFs) were improved compared with CFs. The elastic modulus and hardness of PFs increased with the increase of AAm content. PFs and CFs showed different swelling properties in solutions with different EtOH / H 2 O ratio. Due to the swelling properties difference between CFs and PFs, partial photopolymerized photonic film showed photonic pattern. This research provides a new method to prepare photonic films with sensitive color response to humidity and photonic pattern, which has potential applications in the fields of sensing, anti-counterfeiting, and decoration. [Display omitted] • CNC/AAm/PEG composite film (CF) shows a red shift with increase of AAm content. • CF responses to humidity due to capturing or releasing water molecules in the air. • After photopolymerization, polymer film (PF) was cross-linked and blue-shifted. • The elastic modulus and hardness of PF are significantly enhanced. • Different swelling of CF before and after polymerization resulted in pattern. [ABSTRACT FROM AUTHOR]

A novel strategy adaptive to 3D printing of PLA matrix for complete stereo-complexation was designed. Stereo-complexation has been demonstrated for its effectiveness in simultaneously improving aqueous stability and heat resistance of PLA. However, current techniques could not be directly incorporated into 3D printing of stereo-complexed PLA since stereo-complexed crystallites are easily formed before printing. High printing temperatures are thus required but decompose PLA materials at the same time. The hypothesis for this research is that controllable hierarchical crystallization in three thermal processes, the filament preparation, 3D printing and post annealing, could ensure feasibility of the strategy and a 100% stereo-complexation level in PLA matrices. Effects of extrusion, ambient and annealing temperatures on material structures were analyzed via WAXD, DSC and DMA. Resistance to hydrolysis and heat of the 3D printed PLA matrix was evaluated under practical conditions. It was showed that homo-crystallites anchored molecular chains of PLA during the post-annealing process for a high retention of tensile properties, while stereo-complexed crystallites provided stronger intermolecular interactions for improved hydrolytic and thermal resistance. This novel strategy via incorporating controlled hierarchical crystallization into 3D printing would enrich the fabrication and exploration of high-performance 3D printed PLA materials. • A novel strategy adaptive to 3D printing of stereo-complexed (sc) PLA was designed. • Hierarchical crystallization in three thermal processes ensured feasibility of the strategy. • Effects of homo- and sc-crystallites on PLA properties were systematically studied. • 100% sc-level was achieved in 3D printed PLA matrices. • 3D printed sc-PLA exhibited strong resistance to both hydrolysis and heat. [ABSTRACT FROM AUTHOR]

In this study, silk was dyed into a bright green shade with a natural dye derivative, sodium copper chlorophyllin (SCC). Kinetics and thermodynamics of SCC adsorption on silk in dye bath with and without sodium chloride at different temperatures were investigated. The pseudo second-order kinetic model fitted experimental data well. Addition of sodium chloride increased SCC adsorption at equilibrium qe, increased the diffusion coefficient D and decreased the half dyeing time t1/2. The Langmuir isotherm agreed well with a high correlation coefficient (R2 > 0.99) for dyeing temperatures of 70, 80, and 90 °C with SCC concentration varying from 0.1 to 2.9 g/L. The thermodynamic parameters of SCC adsorption with and without sodium chloride showed significant difference. The adsorption affinity (−Δμ°) and enthalpy change (ΔH°) of SCC dye on silk indicated that the adsorption is a spontaneous and exothermic process. SCC could be a good candidate as a natural green dye for protein fibers. [ABSTRACT FROM AUTHOR]

Abstract: A potential problem for the atmospheric pressure plasma treatment is that the moisture absorbed by the substrate may influence plasma surface modification processes. This study evaluated the effect of moisture regain on the surface morphology change of polyamide fibers by plasma etching. Polyamide 6, poly(p-phenylene terephthalamide) (PPTA, aromatic polyamide), wool (polyamide 2), and ultrahigh modulus polyethylene (UHMPE, polyamide infinity) fibers, were selected to represent various polyamide molecular structures. The fibers were plasma treated at three moisture regains corresponding to three different relative humidity levels (10, 65, and 100%). Scanning electron microscope (SEM) showed that no apparent morphology change was observed on the surface of UHMPE and PPTA fibers. Under the nano-scale surface analysis of atomic force microscopy (AFM), however, rougher surface of UHMPE and PPTA fibers appeared with elevated relative humidity or higher moisture regain. In terms of polyamide 6 and wool, SEM images revealed that compared to the slight plasma etching effect of fibers with the lowest moisture regain, a thin surface layer of the treated fibers with higher moisture regain was partially or completely peeled off. It may be concluded that fiber moisture regain plays an important role in atmospheric pressure plasma etching of polyamide fibers, which may be mainly due to the interaction between the absorbed water and the polymer molecules. It can be concluded that the etching rate of atmospheric pressure plasma for a polymer depends on its moisture regain, intermolecular forces, crystallinity, and molecular structure. [Copyright &y& Elsevier]

• Crosslinkers were developed from oligosaccharides for valorization of keratin wastes. • Oligosaccharide crosslinkers were more effective than other non-toxic crosslinkers. • Crosslinking simultaneously improved strength and elongation of keratin films. • Reaction mechanism between sugar crosslinker and keratin was revealed using analogs. • Relationship between tensile properties and crosslinking degree was quantified. Oligosaccharide derivatives were developed to crosslink keratin materials from poultry feathers, swine bristles and ox hairs to valorize these major wastes from meat industry. Global butchery generates more than 8,600,000 tons of keratinous wastes annually. Keratin was considered a promising resource for developing bio-based products as alternatives to petroleum products. Regenerated keratin products, such as films, usually showed insufficient mechanical properties, and required external crosslinking. However, most crosslinkers for proteins are either toxic, expensive, or with low efficiencies under mild conditions. In this research, regenerated keratin films were crosslinked by oxidized sucrose, a safe and potent bio-polyaldehyde. The crosslinker with verified low toxicity improved both tensile strength and elongation of keratin films, surpassing many other safe crosslinkers. Mechanism of the crosslinking reaction was proposed as forming Schiff bases and aminals and verified via 1H NMR and 13C NMR. Relationship between tensile properties and crosslinking degree of keratin films was also quantified. [ABSTRACT FROM AUTHOR]

PLA bio-composites reinforced by oligo(d -lactic acid) grafted chitosan has been developed for simultaneously improved ductility, strength and modulus. Brittleness problem greatly limits the applications of PLA, a polymer derived from corn. Various methods have been developed to solve the brittleness problem. Unfortunately, these methods have their limitations, such as sacrifice of strength and modulus of PLA, use of toxic chemicals and high costs. Bio-based elastomers such as chitosan also have poor compatibility with PLA, leading to poor mechanical properties. The hypothesis for this research is that CS-g-oligo(D-LA) particles with good ductility could form strong interfacial interactions with PLLA matrix. Reinforcing effect of CS-g-oligo(D-LA) particles on PLLA matrix was systematically studied. Compatibility and intermolecular interactions between CS-g-oligo(D-LA) particles and PLLA matrix were studied by SEM, DSC and 13C NMR analyses. The reinforcing mechanism was summarized. Due to effective transfer of stress from PLLA matrix to the strong but ductile skeletons of CS-g-oligo(D-LA), ductility, strength and modulus of PLLA bio-composites were substantially improved. This novel reinforcing strategy via formation of strong interactions between enantiomeric lactyl units would enrich the fabrication and exploration of high-performance PLA-based bio-composites. Unlabelled Image • PLLA bio-composites reinforced by oligo(D-LA) grafted CS are developed. • Improvement in composite ductility coincides with increase in strength and modulus. • Such result is due to good properties of grafted CS and its compatibility to PLLA. • A small addition of oligo(D-LA)-g-CS is enough to achieve good reinforcing effect. [ABSTRACT FROM AUTHOR]

A new method of combined steam flash-explosion and alkaline treatment (SFE-AT) was developed to extract cellulose fibers from bark of cotton stalks, and lightweight composites with favorable properties were made from the obtained fibers and polypropylene (PP). It was reported that the cellulose fibers from bark of cotton stalks had higher mechanical properties than those from most lignocellulosic byproducts. However, conventional method of using strong alkaline condition (30–100 g/L NaOH) for extraction of cellulose fibers from lignocellulosic byproducts led to environmental pollution and high cost. In this study, bark of cotton stalks were treated using three methods, including alkaline treatment (AT), steam flash-explosion (SFE) and SFE-AT. The different cotton stalk fibers were blended with PP fibers and compression-molded into composites under optimized conditions (temperature of 170 °C, pressure of 3 MPa, 4 min). The results showed that PP composites reinforced by cotton stalk fibers from SFE-AT had the best mechanical properties and stability to water, attributing to the largest surface area and highest cellulose content of cotton stalk fibers by SFE-AT. SFE could separate bark of cotton stalks with high efficiency and subsequent mild AT could sufficiently remove the non-cellulose impurities by using NaOH solution with concentration as low as 5 g/L. Ultra-lightweight PP composites with the bulk density of 0.27 g/cm 3 could be prepared with cotton stalk fibers by SFE-AT. Overall, the method of SFE-AT with high efficiency and low cost could be very useful in exploring industrial applications of bark of cotton stalks and other lignocellulosic byproducts. [ABSTRACT FROM AUTHOR]

A novel toughening technique for 3D printed completely stereo-complexed PLA was devised. Stereo-complexation improves heat and hydrolysis resistance of traditional PLA but intensify its brittleness. Though PBAT elastomer with non-reactive compatibilizer PMMA enhances toughness of traditional PLLA, effects of the two components on crystalline structures and thus heat and hydrolysis resistance of stereo-complexed PLA kept unknown. To add to the challenge, technical difficulties occurred when trying to make stereo-complexation and controlled dispersion of PBAT in the enantiomeric PLA/PBAT/PMMA quaternary system adaptive to 3D printing. The hypothesis is that controlled compatibilization effect of PMMA endows PBAT with good dispersibility in the quaternary system, without affecting the hierarchical crystallization of enantiomeric PLA matrices for complete stereo-complexation. To analyze compatibilization effect of PMMA, interfacial, viscoelastic, crystalline, thermal, thermodynamical, mechanical, and rheological properties were systematically studied. Such a technique provides a new and facile solution to manufacture high-performance 3D printed PLA matrix. [Display omitted] • Strategy adaptive to 3D printing of toughened stereo-complexed PLA was designed. • Controlled compatibilization of PMMA determined the toughening effect. • Controlled compatibilization did not affect hierarchical crystallization of sc-PLA. • Effects of compatibilization effect on PLA properties were systematically studied. • 100% sc-level and high toughness was achieved in 3D printed PLA matrices. [ABSTRACT FROM AUTHOR]

Abstract: We report a novel application of using orange peel as a new natural dyestuff with strong ultraviolet absorbance. Orange peel (OP) is an abundant, cheap and readily available agricultural byproduct. Water extracts from OP were used to dye wool fabrics. Effects of extraction temperature and time on UV–Vis absorbance of the extracted liquor, and effects of dyeing methods and conditions, including pH value, temperature, time and concentration of OP extracts on the colors of the dyed wool fabrics, were studied. OP extracts can be readily sorbed by wool directly, with aluminum or iron mordants, both of which are benign to the environment and human health. The optimum dyeing conditions included dyeing temperature of 100 °C, dyeing time of 120 min, pH 3 for direct dyeing and pH 7–9 for one-bath mordant dyeing. All the dyed wool fabrics demonstrated good colorfastness to washing with soap, good colorfastness to rubbing and acceptable colorfastness to light. Furthermore, OP extracts had strong and durable UV-protection properties. The value of UV-protection Factor (UPF) of the wool fabric dyed with OP extracts using direct dyeing method was about 6 times higher than that of the wool fabric dyed with normal synthetic dyes with similar shade and depth of shade. After 30 home laundering cycles, the UPF value of the former was still about 4 times higher than that of the latter. In general, the abundantly available agricultural byproduct OP has great potential to be utilized as a natural textile dyestuff that could impart textiles with remarkable UV-protection properties. [Copyright &y& Elsevier]

To circumvent wastewater concern of textile industry and cost-effectively utilize waste cooking oil, this study replaced water with waste cooking oil (WCO) in reactive dyeing, and enabled circulated utilization of WCO without jeopardizing dyeing quality, as well as value addition to WCO industry. Current textile dyeing process discharges tremendous amount of wastewater comprised of high concentrations of salts and hydrolyzed dyes. However, none of the existing remediation methods, such as optimization of dyeing processes, chemical modifications of fibers and post-dyeing treatments, showed effectiveness or efficiency. In a dual-phase reactive dyeing, oil and water were used to disperse dye particles and swell cotton fibers. Dyes could be quickly dissolved in water phase and adsorbed into cotton fibers from the interface of water and oil. Though non-edible WCO could be used as a medium for salt-free reactive dyeing, WCO degraded during dyeing and showed gradually deteriorated dyeing quality if repeatedly used. For the first time, this work quantified influence of glycerol and sodium fatty acid, two main WCO hydrolysates, on dyeing results, and revealed the influencing mechanism. As a solution, alkaline refinement was applied after each dyeing cycle to revive functionality of the WCO medium, and could effectively enable WCO reusable in reactive dyeing. Effluent from conventional reactive dyeing could contain up to 100 g/L electrolytes and 50% of initially added dyes, while effluent from WCO reactive dyeing contained no electrolytes and minimal amount of dyes, and could be discharged after simple treatment. Regarding value addition to WCO, textile route might also be economically favorable than biodiesel route. Overall, the WCO reactive dyeing system could have good industrialization potential as a cleaner textile wet process. Image 1 • Waste cooking oil (WCO) was used for cotton dyeing with constantly good quality. • Circulated dyeing of cotton could be realized with minimal waste discharge. • Application of WCO in cotton dyeing had high industrialization potential. • Effluent of WCO dyeing met highest discharge standard with simple treatment. [ABSTRACT FROM AUTHOR]

• GTs were used to prepare CS/GTs composite fiber by blended solution spinning. • CS/GTs fiber has higher dry and wet breaking strength. • Higher breaking strength was due to ionic cross-linking between chitosan and GTs. • CS/GTs fiber has significantly higher antimicrobial and fluorescent properties. Natural extracts gallnut tannins (GTs) were used as functional components to prepare chitosan/gallnut tannins (CS/GTs) composite fiber by blended solution spinning. Chitosan fiber has great potential to be used as absorbent suture and dressing due to its good biocompatibility. However, the weak mechanical properties limited its application. Chitosan and GTs were blended in aqueous solution of acetic acid to spin the composite fiber. The results indicated that CS/GTs fiber can be easily prepared due to the appropriate rheology characteristics for blended solution. Compared with pure chitosan fiber, CS/GTs fiber with 10% GTs showed lower hydrophilicity and higher dry, wet breaking strength by more than 40% due to ionic cross-linking between chitosan and GTs. The bacterial reduction to Staphylococcus aureus increased from 49.0 to 99.7% and about double green and red fluorescent intensity were observed for CS/GTs fiber. GTs have great potentiality in improving the properties of chitosan fiber. [ABSTRACT FROM AUTHOR]