Biodegradable sizing agents from soy protein via controlled hydrolysis and dis-entanglement for remediation of textile effluents.

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.

Halloysite-based inorganic-organic hybrid coatings for durable flame retardant, hydrophobic and antibacterial properties of cotton fabrics.

Developing durable protective cotton fabrics (CF) against potential environmental dangers such as fire hazards and bacterial growth remains an imperative but tough challenge. In this study, flame retardant, antibacterial and hydrophobic CF were successfully prepared via two-step coating. The inner coating entailed polyelectrolyte complexes consisting of polyethyleneimine and ammonium polyphosphate with the goal of enhancing the flame retardancy of CF. Halloysite nanotubes (HNTs), a kind of tubular silicate mineral, were creatively modified and introduced to multifunctional coatings to improve flame retardant and antibacterial properties of CF. N-halamine modified HNTs (HNTs-EA-Cl) and polydimethylsiloxane were applied as the outer coating to endow CF with antibacterial and hydrophobic properties and further improve the flame retardancy of CF. After halloysite-based inorganic-organic hybrid coatings, the limiting oxygen index of the treated samples (PAHP-CF) was over 28 %, and the release of heat and smoke was significantly inhibited. PAHP-CF could inactivate 100 % E. coli and S. aureus within 2 h. More importantly, PAHP-CF showed excellent hydrophobicity with a water contact angle of 148° and exhibited great prevention of bacterial adhesion. PAHP-CF exhibited excellent washing durability undergoing 5 washing cycles. This study promotes the development of multifunctional coatings and offers a new way to manufacture multifunctional cotton fabrics.

Simultaneous toughness and stiffness of 3D printed nano-reinforced polylactide matrix with complete stereo-complexation via hierarchical crystallinity and reactivity.

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 covalent 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.

Hierarchical crystallization strategy adaptive to 3-dimentional printing of polylactide matrix for complete stereo-complexation.

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.

Chitosan/gallnut tannins composite fiber with improved tensile, antibacterial and fluorescence 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.

Effects of monomers and homopolymer contents on the dry and wet tensile properties of starch films grafted with various methacrylates.

Starch grafted with four different methacrylates was compression molded to form thermoplastic films with good strength and water stability. Starch is an inexpensive and biodegradable polymer but is nonthermoplastic and needs to be chemically modified to make starch suitable for various applications. In this research, starch was grafted with four methacrylates (methyl, ethyl, butyl, and hexyl), and the effect of the length of the alkyl ester group on grafting parameters, thermoplasticity, and properties of thermoplastic films developed have been studied. Influence of grafting conditions on % grafting efficiency, % homopolymers, and % monomer conversion were studied, and the grafted starch was characterized using thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and nuclear magnetic resonance ((1)H NMR). At similar grafting ratios, butyl methacrylate (BMA) provided better strength and elongation to the starch films than the other three methacrylates. Grafting of methacrylates appears to be an economical approach to develop thermoplastic products from starch.

Development and characterization of thermoplastic films from sorghum distillers dried grains grafted with various methacrylates.

Distillers Dried Grains (DDG) obtained during production of ethanol from grain sorghum were grafted with methacrylates and compression molded into films with good dry and wet tensile properties. Since sorghum DDG contains up to 45% proteins that are indigestible by animals, it is necessary to find alternative applications to make sorghum ethanol economically competitive. In this research, sorghum DDG was grafted with methyl, ethyl, and butyl methacrylates, the grafted DDG was compression molded into films, and the properties of the grafted DDG and films were studied. At a grafting ratio of 40%, butyl methacrylate (BMA) grafted films had a strength of 4.8 MPa and elongation of 1.8% when dry and 3.1 MPa and 8.1% when wet, indicating that the films had good strength and wet stability. Films developed from grafted DDG show the potential to overcome the brittleness and poor water stability of biopolymer-based films and be useful for various applications.