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This study examined the use of softwood mill residues (50–90%) with two thermosetting resins (i) urea-formaldehyde (UF) and (ii) phenol-resorcinol-formaldehyde (PRF) resin, for potential use in additive manufacturing (AM) of wood composite materials. The curing behavior of these blends was evaluated using differential scanning calorimetry and dynamic rheology. Curing kinetics was determined using the Kissinger and Cranes method. The presence of wood fibers reduced the curing peak temperatures for both resin blends at the same heating rates but curing peak temperatures increased with heating rates. The activation energy (Ea) increased with the addition of wood for the wood-PRF blends but reduced for the wood-UF blends in comparison to the neat resins. Ea values were 51 and 271 kJ/mol for PRF and wood-PRF samples and 100 and 367 kJ/mol for UF and wood-UF samples. Frequency sweep flow curves of the green wood-resin blends showed shear thinning behaviors with viscosity values between 103–108 Pa.s at 30°C. Mechanical properties of the wood-resin composites generally showed a reduction in flexural modulus with an increase in wood content. Wet wood (50%)-PRF blend was successfully extruded and showed promise for use in AM; however, the wood-UF blend was not successful. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the use of waste natural fibers from milled hop bines and hemp stalks, without chemical treatment, and compare them to a commercial wood fiber for use in wood–plastic composite (WPC) materials. The fibers were characterized (density, fiber size and chemical composition). WPCs were produced by the extrusion of a blend of fibers (50%), high-density polyethylene (HDPE) and coupling agent (2%). The WPCs were characterized for their mechanical, rheological, thermal, viscoelastic and water resistance properties. Pine fiber was about half the size of hemp and hop fibers and thus had a higher surface area. The pine WPC melts had a higher viscosity than the other two WPCs. Additionally, the tensile and flexural strengths of the pine WPC were higher than those of hop and hemp WPCs. The pine WPC was also shown to have the least water absorption followed by hop and hemp WPCs. This study highlights that different lignocellulosic fibers influence their WPC properties. The properties of the hop- and hemp-based WPCs were comparable to commercial WPCs and can be improved by further milling/screening the fibers to a smaller particle size (volumetric mean of ~88 μm) to increase their surface area, fiber–matrix interactions and improve stress-transfer. [ABSTRACT FROM AUTHOR]

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) with various 3-hydroxyvalerate (3HV) contents biosynthesized by mixed microbial consortia (MMC) fed fermented dairy manure at the large-scale level was assessed over a 3-month period. The thermal, mechanical, and rheological behavior and the chemical structure of the extracted PHBV biopolymers were studied. The recovery of crude PHBV extracted in a large Soxhlet extractor with CHCl3 for 24 h ranged between 20.6% to 31.8% and purified to yield between 8.9% to 26.9% all based on original biomass. 13C-NMR spectroscopy revealed that the extracted PHBVs have a random distribution of 3HV and 3-hydroxybutyrate (3HB) units and with 3HV content between 16% and 24%. The glass transition temperature (Tg) of the extracted PHBVs varied between −0.7 and −7.4 °C. Some of the extracted PHBVs showed two melting temperatures (Tm) which the lower Tm1 ranged between 126.1 °C and 159.7 °C and the higher Tm2 varied between 152.1 °C and 170.1 °C. The weight average molar mass of extracted PHBVs was wide ranging from 6.49 × 105 g·mol−1 to 28.0 × 105 g·mol−1. The flexural and tensile properties were also determined. The extracted polymers showed a reverse relationship between the 3HV content and Young's modulus, tensile strength, flexural modulus, and flexural strength properties. [ABSTRACT FROM AUTHOR]

ABSTRACT Poly(3-hydroxybutyrate) (PHB) and poly( l-lactic acid) (PLLA) were individually cross-linked with dicumyl peroxide (DCP) (0.25-1 wt %) by reactive melt processing. The cross-linked structures of the polymer gel were investigated by nuclear magnetic resonance (NMR) and Fourier transform infrared (FTIR) spectroscopies. The size of the polymer crystal spherulites, glass transition temperature ( Tg), melting transition temperature ( Tm), and crystallinity were all decreased as a result of cross-linking. Cross-linking density (ν e) was shown to increase with DCP concentration. Based on parallel plate rheological study (dynamic and steady shear), elastic and viscous modulus ( G″ and G′), complex viscosity (η*) and steady shear viscosity (η) were all shown to increase with cross-linking. Cross-linked PHB and PLLA showed broader molar mass distribution and formation of long chain branching (LCB) as estimated by RheoMWD. Improvements in melt strength offer bioplastic processors improved material properties and processing options, such as foaming and thermoforming, for new applications. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41724. [ABSTRACT FROM AUTHOR]

Three industrial lignins (Indulin AT Kraft softwood, Protobind 1000, and corn stover) were fractionated in methanol to obtain soluble and insoluble fractions. The original lignin and obtained lignin fractions were characterized chemically by a combination of FTIR spectroscopy, pyrolysis-gas chromatography–mass spectrum (py-GC–MS), and derivatization followed by reductive cleavage (DFRC). The methanol soluble lignin fractions contained fewer condensed structures than the original lignin and methanol insoluble fractions. The thermal (e.g. glass transition temperature ( T g ) and thermal stability) and rheological properties of the lignins were characterized by a combination of DSC, TMA, TGA and parallel plate rheology. TMA and modulated temperature DSC (MTDSC) proved to be sensitive techniques in determining T g . The methanol soluble lignin fractions had the lowest T g values relative to the original lignin and methanol insoluble fractions. The original lignin and methanol insoluble fractions had a higher thermal degradation temperature relative to the methanol soluble lignin. Solvent partitioning offers a practical approach to fractionate lignin into low M w and T g fractions which show promise as starting materials for making lignin-copolymers. [ABSTRACT FROM AUTHOR]

The popularity and demand for wood plastic composites (WPC) has focused research on fiber properties associated with performance. In this study, maple wood fibers (WF) were ball milled and classified into discrete size fractions. Fiber analyses showed only three distinct WF size classes (80-100, 100-200 and <200 mesh). High density polyethylene (HDPE) based WPC were made from classified WF (10 to 50%). The effect of WF size, loading, and maleated polyethylene (MAPE) coupling agent on WPC rheological behavior (torque rheometry and melt flow rate (MFR)) and flexural properties were examined. The WPC MFR decreased with wood loading, increased with a reduction in WF size. The modulus of rupture (MOR) was shown to increase with a reduction in WF size and increase with the addition of MAPE. The increase in MOR is likely due to an increase in the interfacial interaction between the polymer and WF. Modulus of elasticity (MOE) was shown to increase with an increase in wood loading and decrease with a decrease in WF size. The toughness of the WPC was shown to increase with a decrease in WF size and increase upon addition of MAPE. [ABSTRACT FROM AUTHOR]

Abstract: Complete use of all major components of biomass is critical to make algal biofuel feasible. Therefore, a sequential hydrothermal liquefaction process was developed as an extraction technology to fractionate the polysaccharides and the lipids from algal cells. This technology was used to process Chlorella sorokiniana biomass by extracting polysaccharides from the biomass at lower temperature followed by liquefaction of the extracted residue to bio-oil at higher temperatures. The extracted polysaccharides were characterized to evaluate its potential industrial applications. Structural and chemical characteristics of crude polysaccharides were determined by different spectroscopic analysis. Monosaccharide composition and linkage analysis revealed that >90% of the polysaccharide is composed of 1→4 linked glucan. As quantified based on molecular weight cut off of the dialysis bag, 68–70% of the ethanol insoluble polysaccharide showed to have a molecular weight >10,000g/mol. The polysaccharide exhibited pseudoplastic behavior at 0.05g/ml which could be maintained over a NaCl concentration of 0.1 to 3M. Thermogravimetric analysis (TGA) and differential scanning calorimetric analysis (DSC) were also conducted to evaluate the thermal property of the polysaccharide. Various industrial applications were suggested based on the measured characteristics of the polysaccharides. [Copyright &y& Elsevier]

Utilisation of lignin in plastic based blends offers a sustainable alternative to non-renewable materials as well as value-added use of technical lignin obtained from pulping operations. To overcome poor compatibility between lignin and plastic, in this study, two industrial lignins (softwood Kraft and agricultural fiber soda) were esterified (with acetic, propionic, butyric, and hexanoic anhydrides) and subsequently blended with poly(3-hydroxybutyrate- co -3-hydroxyvalerate) (PHBV) or polypropylene (PP) at a weight ratio of 3:7. This paper systematically characterized C 2 –C 6 anhydrides esterified lignins (molar mass, glass transition temperature (T g ), hydrophobicity, and polarity), and provides a comprehensive evaluation of the effect of different lignin esters in the blends on tensile properties, water absorption, thermal transitions, for the first time, spherulite morphology, and dynamic rheological behaviour. Generally, compared to blends with unmodified lignin, a progressive increase of tensile strength (25%) and elongation at break (26%) could be observed with increasing ester carbon chain length in PHBV based systems, while no improvement was seen in PP based systems. Water absorption of PHBV and PP blends decreased by about 50% after lignin esterification. The effect of lignin esterification on the crystallization process was matrix dependent: depression of melting crystallization and occurrence of cold crystallization was observed in PHBV based blends, while the melting crystallization shifted to higher temperature in PP based blends. The lignin acetate and propionate blends were partially miscible showing two-stage glass transitions by thermal mechanical analysis. Esterification led to more uniform dispersion of lignin in the plastic matrix. The frequency of PHBV spherulites increased and their size decreased from 700 μm to less than 100 μm with addition of lignin acetate and propionate. Lignin hexanoate blends showed a T g depression and smaller dynamic elastic and viscous moduli than the other lignin esters, suggesting that it acted as a plasticizer. [ABSTRACT FROM AUTHOR]

Inthis work we report on the preparation, characterization, andproperties of a thermally treated lignin-derived, phenolic-rich fraction(PRF) of wood pyrolysis bio-oil obtained by ethyl acetate extraction.The PRF was characterized for viscoelastic and rheological behaviorusing dynamic mechanical analysis (DMA) and cone and plate rheology.A unique thermoplastic behavior was evidenced. Heat-treated PRFs acquirehigh modulus but show low temperatures of thermal flow which can besystematically manipulated through the thermal pretreatment. Lossof volatiles, changes in molecular weight, and glass transition temperature(Tg) were investigated using thermogravimetricanalysis (TGA), mass spectrometry (MS), and differential scanningcalorimetry (DSC), respectively. Underlying mechanisms for the thermaland rheological behavior are discussed with regard to interactionsbetween pyrolytic lignin nanoparticles present in the system and therole of volatile materials on determining the properties of the materialresembling in several aspects to colloidal suspension systems. Lowthermal flow temperatures and reversible thermal effects can be attributedto association of pyrolytic lignin particles due to intermolecularinteractions that are easily ruptured at higher temperatures. Thethermoplastic behavior of PRF and its low Tgis of particular interest, as it gives opportunities for applicationof this fraction in several melt processing and adhesive technologies. [ABSTRACT FROM AUTHOR]