增容剂PE-LD-g-MAH对低密度聚乙烯／木质素共混体系性能的影响

研究了低密度聚乙烯(PE-LD)与马来酸酐(MAH)的接枝共聚物PE-LD-g-MAH对低密度聚乙烯/木质素共混体系微观形态、流变行为、热性能和力学性能的影响。DSC-TC综合热分析表明,添加增容剂的共混体系的熔融温度降低,热稳定性提高;流变性能分析表明,共混体系的加工性能良好;扫描电子显微镜(SEM)分析显示,添加增容剂后木质素分散相尺寸明显减小,分散程度提高;PE-g-MAH可以有效提高低密度聚乙烯/木质素吹塑薄膜的力学性能,且当木质素、低密度聚乙烯和PE-LD-g-MAH质量比为25/75/10时,力学性能最优。     

Effect of lignin on mechanical,biodegradability, morphology,and thermal properties of polypropylene/polylactic acid/lignin biocomposite

ABSTRACT

The effects of lignin on mechanical, biodegradability, morphology, and thermal properties of PP/PLA/lignin were investigated. PP/PLA/lignin film were manufactured by adding PP, PLA, lignin and compatibilizer into rheomix at 200°C, at 70?rev?min^?1 for 30?minthen pressed using Hydraulic Hot Press at 200°C–210°C, at 6 bar for 20?min. The functional groups of PP/PLA/lignin were analyzed using FTIR. The surface morphology, mechanical properties and thermal stability was measured by SEM, tensile strenght and TGA respectively. TThe FTIR intensity of vibration peak of –CH₃?cm^-1 from PP/lignin and PP/PLA/lignin at 997–993, 1458–1451 and 2966–2904?cm^-1 was lower than neat PP. The addition of lignin into PP/lignin, PLA/lignin and PP/PLA/lignin can reduce tensile strength and elongation at break. The thermal stability PP/PLA/lignin was lower than the PP/lignin but higher compared to PP/PLA biocomposites. The biodegradability of PP/PLA/lignin biocomposites was two times higher than that of PP/lignin.     

Investigation of oil palm based Kraft and auto-catalyzed organosolv lignin susceptibility as a green wood adhesives

The aim of this study is to highlight the application and potentiality of oil palm based lignins in the synthesis of green phenolic resins. The delignification processes were conducted using Kraft and auto-catalyzed ethanol–water pulping processes. The extracted lignins were characterized using elemental analysis, Fourier transform-infrared, ¹H and ¹³C nuclear magnetic resonance (NMR) spectroscopy, molecular weight distribution (M_n, M_w and polydispersity), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The obtained FTIR results revealed that the Kraft lignin contained substantial amounts of guaiacyl units with smaller amounts of syringyl units. The molecular weight of Kraft lignin was 1564 g mol⁻¹ which is higher than organosolv lignin at 1231 g mol⁻¹. The activated free ring position (2.99%) of Kraft lignin was comparatively higher than that of organosolv lignin (2.06%) which was measured using Mannich reactivity analysis. Thermal analysis of Kraft lignin showed higher thermal stability compared to organosolv lignin. The structural and thermal characteristics implied that Kraft lignin had higher potential for the production of green phenolic resins when compared with organosolv lignin.     

Multtphase Materials with Lignin. III. Polyblends with Ethylene-Vinyl Acetate Copolymers

Abstract

Organosolv lignin (OSL) from red oak, and its corresponding hydroxypropyl lignin (HPL) derivative, were blended in the melt with polyethylene and with ethylene-vinyl acetate (EVA) copolymer, and injection molded. Lignin (derivative) content and vinyl acetate (VA) content both served as process variables. All mixtures produced immiscible blends, both by scanning electron microscopy and dynamic mechanical analysis. However, the compatibility of the two polymers increased with VA content. Both lignin products proved to be effective modulus builders, but. HPI, was more effective than OSL at VA contents above 20%. Modulus increased roughly in accordance with the rule of mixing. Inferior tensile strength properties were observed with the EVA copolymer if VA content was below 10%, and superior characteristics were noted in materials containing more than 25% VA and between 5 and 20% HPL.     

Reduction of Formaldehyde Emission from Particleboard by Phenolated Kraft Lignin

The aim of this study was the reduction of formaldehyde emission from particleboard by phenolated Kraft lignin. For this purpose, the lignin was extracted from black liquor and then modified by phenolation. During the urea formaldehyde (UF) resin synthesis different proportions of unmodified and phenolated Kraft lignins (10%, 15%, and 20%) were added at pH = 7 instead of the second urea. Physicochemical properties and structural changes of resins so prepared, as well as the internal bond (IB) strength and formaldehyde emission associated with the panels bonded with them were measured according to standard methods. The Fourier transform infrared (FTIR) analysis of lignin indicated that the content of O–H bonds increased in phenolated lignin while the aliphatic ethers C–O bonds decreased markedly in the modified lignin. Since both synthesis of UF resins and lignin phenolation are carried out under acid conditions, phenolation is an interesting way of modifying lignin for use in wood adhesive. The panels bonded with these resins showed significantly lower formaldehyde emission compared to commercial UF adhesives. The UF resin with 20% phenolated lignin exhibited less formaldehyde release without significant differences in internal bond strength and physicochemical properties compared to an unmodified UF resin. XRD analysis results indicated that addition of phenolated lignin decreased the crystallinity of the hardened UF resins.     

Lignin in jute fabric–polypropylene composites

In this work, the feasibility of using lignin as a compatibilizer for composites made from jute fiber fabric and polypropylene (PP) was studied. Since lignin contains polar (hydroxyl) groups and nonpolar hydrocarbon, it was expected to be able to improve the compatibility between the two components of the composite. It was found that lignin acted as β nucleation, fire retardant, and toughening agent for PP matrix. Jute composites exhibit higher stiffness, tensile strength, and impact behavior in respect to those of neat PP. Although scanning electron micrographic observations indicate that PP‐jute adhesion was slightly improved by lignin addition, additional benefits were only obtained from impact behavior. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Separation of Alcohols from Solution by Lignin Gels

Abstract

Partition relationships of radioisotope labeled ethanol and 1-butanol between aqueous solutions and a hydrated commercial Kraft softwood lignin gel are presented. These initial evaluations indicate that lignin hydrogels preferentially concentrate 1-butanol and, to a lesser extent, ethanol. The process implications and potential use of lignin as an inexpensive extractant are discussed.     

Epoxidation of Methanol-Soluble Kraft Lignin for Lignin-Derived Epoxy Resin and Its Usage in the Preparation of Biopolyester

Most commercial epoxy resins have been produced using toxic bisphenol A. Lignin can be utilized as green substitute for bisphenol A to produce bio-epoxy resins. Methanol-soluble kraft lignin was extracted by methanol fractionation for lignin epoxidation, and epoxidized into lignin-derived epoxy resin via two-step epoxidation consisting of epichlorohydrin addition and epoxide ring restructuring. Epoxidized lignin was selectively separated from non- or less-reacted lignin based on their solubility differences in organic solvents. The existence of epoxide groups in the lignin-derived epoxy resin was confirmed using FT-IR, ¹H-NMR, and TGA analyses. Epoxidized lignin was used as a reactive lignin macromonomer to prepare biopolyester. The characteristics of the synthesized biopolyester were analyzed using FT-IR, and the thermal properties were analyzed by TGA. The thermal decomposition temperature of 5% weight loss (T_d5) was determined to be 257.1°C, which is comparable to epoxy resins that are used in electronic applications.     

增容剂LDPE-g-MAH对木质素/聚乙烯吹塑薄膜形貌与性能的影响

研究了低密度聚乙烯与马来酸酐的接枝共聚物LDPE-g-MAH对木质素/低密度聚乙烯共混体系热性能、红外光谱分析力学性能、流变行为以及微观形态的影响.DSC-TG综合热分析表明添加增容剂的共混物的熔融温度降低,热稳定性提高;红外光谱分析表明木质素与LDPE-g-MAH之间存在分子间氢键相互作用,流变性能分析表明共混物体系具有可加工性;扫描电子显微镜（SEM）照片显示添加增容剂后分散相尺寸明显减小,分散程度提高;PE-g-MAH有效提高了木质素/聚乙烯吹塑薄膜的力学性能,且当木质素、聚乙烯和LDPE-g-MAH质量比为25/75/10时,力学性能最优.     

Sulfonation of Phenolated Kraft Lignin to Produce Water Soluble Products

Kraft lignin is water insoluble and has limited end-use applications. To produce water soluble lignin-based products, the modification of softwood kraft lignin through phenolation followed by sulfonation of sulfuric acid or sodium sulfite treatment were investigated in this work. Fourier transform infrared (FTIR) spectrophotometer, nuclear magnetic resonance (NMR), and thermo-gravimetric analysis were also considered for characterizing the lignin-based products. The results showed that phenolation pretreatment was effective to generate sulfonated lignin (SAP-lignin) by sulfuric acid treatment with a high charge density (3.12 meq/g) and solubility, which is due to the addition of sulfonation sites on the phenolic ring. However, sodium sulfite treatment of phenolated lignin generated sulfonated lignin (SSP-lignin) with the charge density of 1.20 meq/g due to hindered sulfonation by occupation of reactive α-position. SAP-lignin was soluble across the tested pH range of 1–13, but SSP became insoluble at a pH lower than 3. Thermogravimetric analysis revealed that phenolation pretreatment reduced the thermal resistance of modified lignin when compared to kraft lignin, while SAP-lignin exhibited the highest thermal resistance due to condensation under sulfuric acid treatment. SAP- and SSP-lignin were successfully used as a coagulant for dye removal from simulated solutions as they could remove 72.1 and 90.4% of ethyl violet from a simulated dye solution, respectively.     

Preparation and Characterization of Poly (vinyl chloride) Polyblends with Fractionated Lignin

Soda lignin was divided into three fractions by sequential extraction with i-propanol/ethanol mixture (4:1v/v) and methanol. Blends of poly (vinyl chloride) (PVC) and lignin were prepared from these lignin fractions. The influences of lignin on the processabilities of the blends, as well as on their mechanical performances and thermal properties, were investigated. The lignin fraction with low molecular weight accelerates the plasticization of blend. It can be dispersed in a rather uniformly form in PVC matrix than any other fractions. The blend prepared from low-molecular-weight lignin fraction exhibits higher mechanical performances than those of blends prepared from any other fractions. The initial decomposition temperature of blends shows a slight decrease, while the incorporation of high-molecular-weight lignin fraction improves the maximum decomposition temperature of blend. The heterogeneity of soda lignin results in the deteriorated mechanical performances of the blend prepared from un-fractionated lignin.     

Liquid Lignin from the SLRPTM Process: The Effect of Processing Conditions and Black-Liquor Properties

CO₂ acidification of Kraft black liquors was performed at temperatures of 100–150°C and pressures of 5–8 bar in an investigation of the SLRP^TM process. At these conditions, a highly hydrated, lignin-rich liquid (vs. the usual solid) separated out to form a new phase. The solids content/ionic strength of the starting black liquor was found to be a key variable for controlling the bulk and molecular properties of the ?liquid-lignin” (LL) phase. For example, black liquors of lower ionic strengths (20% solids) produced LLs with lower ash contents and higher molecular weights, albeit in lower yields. In contrast, higher ionic strengths/solids content (40%) produced LLs in higher yields with higher aromatic and aliphatic hydroxyl contents. Temperature effects were significant only at the highest levels. The degree of hydration of the LL phase was found to be a useful measure of the water available for hydration of ionized/polarizable groups in lignin.     

Scale of Homogeneous Mixing in Miscible Blends of Organosolv Lignin Esters with Poly(ϵ-caprolactone)

Abstract

Organosolv lignin (OSL) esters (side-chain carbon number, n = 3, 4, and 5) have been demonstrated to be miscible with poly(?-caprolactone) (PCL) on a scale (20–30 nm) for detecting glass transition temperature (T _g) by differential scanning calorimetry (Polym. J. 2009, 41(3), 219–227). Further precise quantification of homogeneity was conducted for the OSL propionate (OSL-Pr, n = 3)/PCL and OSL butyrate (OSL-Bu, n = 4)/PCL blends by means of dynamic mechanical analysis (DMA) and solid-state nuclear magnetic resonance (NMR). DMA revealed a composition-dependent T _g for these blend samples, which implies the attainment of an intimate mixing of the ingredients on a scale of ≤15 nm. From the measurements of proton spin-lattice relaxation times (T _1ρ ^H) using solid-state NMR, the blends were estimated to be substantially homogeneous on a scale of ～6 nm. But the equalization of the T _1ρ ^H for the components of OSL-Pr/PCL was not remarkable; that is, the constituents of OSL-Pr/PCL were relatively imperfectly miscible with each other.     

Bio-renewable precursor fibers from lignin/polylactide blends for conversion to carbon fibers

Lignin, a highly aromatic biopolymer extracted as a coproduct of wood pulping, was investigated as a suitable precursor for carbon fibers. Lignin was chemically modified and blended with poly(lactic acid) (PLA) biopolymer before melt spinning into lignin fibers. The chemical modification of raw lignin involved butyration to form ester functional groups in place of polar hydroxyl (–OH) groups, which enhanced the miscibility of lignin with PLA. Fine fibers were extracted and spooled continuously from lignin/PLA blends with an overall lignin concentration of 75 wt.%. The influence of chemical modification and physical blending of lignin with PLA on the resulting fiber was studied by analyzing the microstructure of the fibers using transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The influence of blend composition on the phase behavior was studied by differential scanning calorimetry (DSC). The effect of composition on the mechanical properties was studied by tensile tests of the lignin/PLA blend fibers. The thermal stability and carbon yield of the blended fibers with different concentrations of lignin were characterized by thermogravimetric analysis (TGA). The microstructure analysis of carbon fibers produced from lignin/PLA blends revealed composition dependent microporous structures inside the fine fibers.     

Influence of Lignin Type on the Mechanical Properties of Lignin Based Compounds

Several types of sulfur‐free lignins were melt compounded in a Werner & Pfleiderer twin screw extruder (ZSK 25) together with polyamide 11 (PA11), a biodegradable polyester (Ecoflex®) and a biodegradable polyesteramide (BAK®). Sulfur‐free lignins, precipitated from black liquors of alkaline pulping of annual plants, like sisal and abaca, were compared to a sulfur‐free lignin (Alcell™) obtained by organosolv wood pulping. Lignin content and lignin type were varied systematically in order to examine stress/strain characteristics and impact behavior. Compounds with lignins from annual plants showed similar or better mechanical properties in comparison to compounds with Alcell™ lignin. A polyamid 11 compound containing 30 wt.‐% abaca lignin gave a Young's modulus of 1 890 MPa, compared to 1 420 MPa for PA11 and a 28% increase of yield stress. The morphology of the lignin compounds was investigated by means of environmental scanning electron microscopy (ESEM) and transmission electron microscopy (TEM).     

Kraft Lignin-Based Rigid Polyurethane Foam

Abstract

Kraft pine lignin was derivatized to a liquid polyol through oxypropylation. The resulting polyol was characterized by GPC, FT-IR, H¹, C¹³, and P³¹ NMR and was compared to commercial polyols in view of the mechanical property of the corresponding rigid polyurethane foams for the first time. A series of lignin-based PU was synthesized by replacing varying weight percentages of the amount of sucrose polyol and glycerol polyol, two commonly used commercial polyols employed in the control foam preparation. All foams had a low density of ～30 Kg m^?3 and showed typical linkages of PU in the FT-IR spectra. The diameter of closed-cells was ～650 μm for most of the foams as revealed by SEM images. The optimal compressive property of rigid PU foams was obtained using lignin polyol without the addition of any other commercial polyols primarily attributed to the rigidity of lignin aromatic structure and the high functionality of lignin hydroxyl groups.     

Esterification of Kraft lignin as a method to improve structural and mechanical properties of lignin‐polyethylene blends

Lignin is a promising candidate for blends with thermoplastic polymers. Still, this endeavour is a challenge due to poor compatibility between both components. In this article, the effect of lignin esterification on the improvement of the compatibility between hardwood Kraft lignin and high‐density polyethylene (PE‐HD) is investigated. For this purpose, lignin was esterified with acetic, propionic, and butyric anhydride; its amount in the blends varied from 10 to 40%. Light microscopic images of blends show a reduction in particle size and a more homogeneous distribution with increasing length of the ester carbon chains (C2 to C4). Modification of lignin enhances the moduli and strength characteristics of the blends. Butyrated lignin performs best, as tensile strength of blends can be retained near that of pure PE‐HD with up to 40% lignin content. An additional investigation of unmodified lignin with reduced particle size confirms that modification is the decisive factor to enhance blend properties; a sole reduction of particle size is insufficient. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44582.     

Lignin liquefaction under microwave heating

Organosolv lignin from olive tree pruning was subjected to liquefaction under microwave heating and modifying the experimental conditions (time, temperature, and concentration of catalyst) according to an experimental design. The organosolv lignin and obtained polyols were characterized using attenuated‐total reflection infrared spectroscopy (ATR‐IR), thermogravimetric analysis (TGA), gel permeation chromatography, and another parameter such as the hydroxyl number (I_OH). The ATR‐IR and the TGA results showed that the solvents (polyethylene glycol #400 and glycerol) reacted with the lignin being present in the final product. The optimal polyol showed a liquefaction yield of 99.07% that was obtained in 5 min of reaction at 155°C with 1% of sulphuric acid. The liquefaction product showed a hydroxyl number of 811.8 mg KOH/g, suitable to be used as a precursor in polyurethane foam synthesis. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3292–3298, 2013     

Reactive compatibilization of PLA/TPU blends with a diisocyanate

This study focuses on the compatibilization of poly(lactic acid) (PLA)/thermoplastic polyurethane (TPU) blends by using 1,4 phenylene diisocyanate (PDI) for the first time, as the compatibilizer. Because of the potential interactions of diisocyanates with ? OH/? COOH, they are useful for reactive processing of PLA/TPU blends in the melt processing. To have insight on the reactively compatibilized structure of PLA/TPU blends, phase morphologies are observed by means of scanning electron microscopy. The mechanical, thermal, and rheological responses of the blends are investigated. The observations are that the brittle behavior of PLA changes to ductile with the addition of TPUs. The addition of PDI improves the tensile properties of the blends. The compatibilization action of PDI is monitored with DMA and rheological experiments. Cross‐over in the G′ and G″ curves of compatibilized blends indicates the relaxation of branches formed in the presence of PDI. The dispersed phase size of TPU decreases in PLA in the presence of PDI due to the improved compatibility. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40251.     

Effect of kraft lignin on protein aggregation,functional, and rheological properties of fish protein‐based material

The main drawbacks of protein‐based bioplastics are a high sensitivity to water, insufficient mechanical properties, and a narrow window of processing conditions. The objective of this work was to study the effect of Kraft lignin (KL) on protein aggregation, functional, and rheological properties of fish protein (FP)‐based bioplastic. FP powder was blended with 30% glycerol and 0–70% KL. Then, blends were thermoformed by compression molding. KL addition increased protein solubility in sodium dodecyl sulfate buffer, indicating a decrease of protein molecular weight. An introduction of KL in protein blend increased mechanical properties and decreased water absorption of materials. KL addition resulted in a decrease in storage modulus in rubbery state of protein blends. It also resulted in a decrease in viscosity of protein blends at processing temperature, as determined by capillary rheometry. Therefore, KL is an alternative additive to enlarge the protein thermal processing window and improve functional properties of FP‐based materials. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013