废旧硬质聚氨酯泡沫塑料的木质素改性及再生

采用含有二乙二醇(DEG)和乙醇胺(ETA)的双组分解交联剂降解废旧硬质聚氨酯泡沫塑料(PU硬泡),并利用降解得到的低聚物多元醇与木质素复合制备出性能增强的再生PU硬泡。通过对制备的再生PU硬泡的红外光谱、密度、吸水率、抗压强度、热稳定性、导热系数、热重曲线等进行分析测试,考察m(DEG)∶m(ETA)对再生PU硬泡性能的影响。实验结果表明:m(DEG)∶m(ETA)=1∶3时废旧PU硬泡的降解效果最好;木质素加入量为2.0%(w)时再生PU硬泡的密度低、抗压强度高、保温性能良好,达到国家标准《建筑绝热用硬质聚氨酯泡沫塑料》(GB/T 21558—2008)的品质要求。     

Effects of Wood Fiber and Microclay on the Performance of Soy Based Polyurethane Foams

Various polyurethane (PU) foams were prepared by in situ reaction of isocyanate and soy-based polyol. The effects of wood fiber and microclay on the foam morphologies, mechanical properties and thermal behaviors of PU foams were investigated. NCO index had fundamental impacts on the influences of wood fiber and microclay on the performance of PU foams. The reinforcement behavior of flexible foams was different to that of both semi-rigid and rigid foams. Both fiber and microclay improved the compressive strength at a high NCO index of 140–250, and contributed to relative high decomposition temperatures. Unlike the compressive strength, the tensile strength was decreased due to the amount of hard polyurea formation from secondary reactions at the highest NCO level. In addition, wood fiber had different reinforcement mechanism from microclay. Wood fiber desired to form chemical bonds during foaming while microclay had potential to form physical insertions. This difference was expressed by the change of their thermal degradation temperature.     

Thermal and Mechanical Properties of Polyurethane Rigid Foam Based on Epoxidized Soybean Oil

A soypolyol based on epoxidized soybean oil (ESO) was prepared in the presence of HBF₄ and diethanolamine (DEA) was used as ring opener. A series of polyurethane rigid foam were prepared by mixing polyol with TDI using an isocyanate index of 1.1. The polyol used in this paper were a mixture of soypolyol and a commercial PL-5601 polyester polyol and the mass fraction of PL-5601 was in the range of 0–60%. The thermal properties of the resins were characterized by DSC and TG. The results showed that these rigid foams possess high thermal stability. There were two glass transition temperature of each foam and Tg₁ was increasing with the increasing of OH value. The compression strength of the foam was also recorded, and the effect of mass ratio of soypolyol and PL-5601 polyester polyol on the compression strength was discussed.     

Structure,Mechanical, Thermal and Fire Behavior Assessments of Environmentally Friendly Crude Glycerol-Based Rigid Polyisocyanurate Foams

In this work, rigid polyisocyanurate foams were prepared at partial substitution (0–70 wt%) of commercially available petrochemical polyol, with previously synthesized biopolyol based on crude glycerol and castor oil. Influence of the biopolyol content on morphology, chemical structure, static and dynamic mechanical properties, thermal insulation properties, thermal stability and flammability was investigated. Incorporation of 35 wt% of crude glycerol-based polyol had reduced average cell size by more than 30% and slightly increased closed cell content, simultaneously reducing thermal conductivity coefficient of foam by 12% and inhibiting their thermal aging. Applied modifications showed also positive impact on the mechanical performance of rigid foams. Increase of crosslink density resulted in enhancement of compressive strength by more than 100%. Incorporation of prepared biopolyol resulted in enhancement of thermal stability and changes in degradation pathway. Up to 35 wt% share of crude glycerol-based polyol, foams showed similar flammability as reference sample, which can be considered very beneficial from the environmental point of view.     

A Novel and Formaldehyde-Free Preparation Method for Lignin Amine and Its Enhancement for Soy Protein Adhesive

In this work, a novel two-step process to prepare primary lignin amine was developed. The lignin used in this study was obtained from the residue of cellulosic sugar fermentation for bioethanol (referred as “lignin”). The lignin was initially oxidized through Fenton oxidation. The oxidized lignin was further converted to lignin amine by reductive amination. Ammonia was used in the second step leading to give the highly active primary lignin amine. The oxidation and reduction exhibited relatively high yields of 80.0 and 91.2 % respectively. For comparison, lignin was partially depolymerized via mild hydrogenolysis and then the partial depolymerized lignin was also converted to lignin amine using the same method. The obtained lignin amines were characterized in detail using elemental analysis, proton nuclear magnetic resonance (¹H NMR), and Fourier transform infrared spectroscopy (FTIR). Further, modification of soy protein adhesive by lignin amine was exemplified in wood bonding, and the results indicated that addition of lignin amine greatly increased water resistance of soy protein adhesives.     

Influence of Palm Oil-Based Polyol on the Properties of Flexible Polyurethane Foams

This paper describes the effect of the modification of polyurethane system with palm oil-based polyol on the cell structure and physical?Cmechanical properties of polyurethane foams. Flexible polyurethane foams were prepared by substituting a part of petrochemical polyether-polyol with the palm oil polyol. Selected physical?Cmechanical properties of these foams were examined and compared to the properties of reference foam. The properties such as apparent density, tensile strength, elongation at break, resilience, compressive stress and thermal stability were analyzed. It was found that the modifications of polyurethane formulation with palm oil polyol allow to improve selected properties of final products.     

Sugarcane Bagasse Paper Reinforced by Cellulose Nanofiber (CNF) and Bleached Softwood Kraft (BSWK) Pulp

This study explores the effects of bleached softwood kraft pulp (BSWK) as a conventional reinforcing material in comparison with cellulose nanofiber (CNF) as an emerging bionanomaterial on the bleached soda sugarcane bagasse (BSSB) paper furnish. Cationic polyacrylamide was selected as a retention aid along with the CNF addition to retain it on fiber surfaces during the papermaking process. The results showed that though the effects of CNF were similar to those of BSWK in the most of properties but there were some important differences which can industrially be noticeable. In one hand, both of cellulosic elements, when substituted for the BSSB at the 5 or 10 % levels, gave increases in the paper strength, i.e. samples containing 10 % CNF yielded similar tensile strength (53 N m/g) and a more consolidated structure (14 % increment of the density) than those produced with 10 % BSWK. CNF addition had opposite effects on the air-permeability of the resulting paper. Unlike BSKW, the addition of CNF had a strong favorable effect on tear strength, but it was markedly slowed the rate of drainage time when it was especially added at 10 % level of the final furnish.     

Study on Properties of Poly(urethane-ester) Synthesized from Prepolymers of ε-Caprolactone and 2,2-Dimethyl-1,3-Propanediol Monomers and Their Biodegradability

Poly(urethane-ester) was prepared by polymerization of 4,4′-methylenebis(phenyl isocyanate) (MDI) and prepolymers of ε-caprolactone and 2,2-dimethyl-1,3-propanediol monomers P(CL-DP) with various chain lengths as polyol sources. Characterizations of poly(urethane-ester) were carried out by analysis of functional groups (FTIR), thermal properties (DTA/TGA), mechanical properties (Tensile tester), crystallinity (XRD), and biodegradability. The chain length of prepolymers used in polymerization has a significant effect in properties of poly(urethane-ester) as well as their biodegradability. The formation of poly(urethane-ester) was indicated by the presence of new absorption peaks at wave number of 3,348.2 and 1,596.9 cm^?1 for urethane (–NH–) and aromatic groups in chain of polymers, respectively. The increase chain length of prepolymer used in polymerization with 4,4′-methylenebis(phenyl isocyanate) was observed the increase thermal property and crystallinity of poly(urethane-ester). However, the maximum mechanical property and also biodegradability in activated sludge were observed in poly(urethane-ester) prepared by polymerization of 4,4′-methylenebis(phenyl isocyanate) (MDI) and P(CL-DP) prepolymers with DP/CL ratio of 1/20. Apparently, the amorphous parts of polymers are rapidly decomposed by enzymes of microorganisms, so the crystallinity on the whole of poly(urethane-ester) increases after incubation time of 30 days.     

Improvement of Synthesis and Dielectric Properties of Polyurethane/Mt-QASs<Superscript>+</Superscript> (Novel Synthesis)

Polyurethane-based nanocomposites were prepared and their dielectric properties were characterized. Polyurethane (PU) composites were prepared with different organoclay content (1, 3, 5, and 10 wt% for all cases). The composites included quaternary ammonium salts such as 1-methyl-di-octyl-1 phenyl ammonium iodide (QAS-1), 1-methyl-di-nonyl-1 phenyl ammonium iodide (QAS-2), and 1-methyl-di-dodecyl-1 phenyl ammonium iodide (QAS-3) which were newly synthesized for modification of Na⁺-montmorillonite. Addition of aluminum silicate enhanced the dielectric properties at a constant concentration. Dielectric constants of nanocomposites compounded with 3 %- and 5 %-organoclay were close in value. The characterization of PU/organoclay composites was carried out using Fourier transform infrared and X-ray diffraction.     

A Comparison of Modified and Unmodified Cellulose Nanofiber Reinforced Polylactic Acid (PLA) Prepared by Twin Screw Extrusion

The goal of this work was to evaluate the effect of chemical modification of cellulose nanofibers (CNF) on the properties of polylactic acid (PLA) nanocomposites. Acetylated nanofibers (ACNF), with degree of substitution 1.07, were isolated from acetylated kenaf fibers by mechanical treatments. Acetylated nanofibers showed more hydrophobic properties compared to non-acetylated ones. The results showed that both crystallinity and thermal stability of acetylated nanofibers were lower than non-acetylated ones. The nanocomposites were prepared by premixing two PLA master batches, one with a high concentration of ACNF and the second with CNF. These were diluted to final concentrations (5?wt%) during the extrusion. The morphology studies of PLA and its nanocomposites showed nanofiber aggregates in both materials. The results showed that the tensile and dynamic mechanical properties were enhanced for both acetylated and non-acetylated nanocomposites compared to the neat PLA matrix while no significant improvement was observed for the acetylated nanocomposites compared to non-acetylated ones. However, the storage modulus increased slightly for acetylated nanocomposites compared to non-acetylated ones.     

Synthesis of Soy-Polyol by Two Step Continuous Route and Development of Soy-Based Polyurethane Foam

Soy-polyol has been synthesized via a low energy two-step continuous route thus avoiding intermediate steps and chemicals. The functional groups of soy-polyol thus produced were identified by Fourier transform infrared (FTIR) spectroscopy which confirmed the cleavage of the double bonds, the formation of new epoxy linkages and the presence of hydroxyl groups. The change in chemical structure and physical properties of the soy polyol was further characterized and the results indicated a successful conversion with reduced unsaturation, increased hydroxyl number and increased viscosity. Polyurethane foam was prepared from soy-polyol using isocyanate and thermogravimetric analysis was used to study its thermal decomposition behaviour. Multiple transitions were identified in relation to depolymerization and bond dissociation. Density and compressive strength of the soy-foam were found to be satisfactory. An investigation of microstructure of soy foam by scanning electron microscope and X-ray computed tomography revealed the internal cell morphology and cell structure.     

Thermo-Chemical Decomposition Study of Polyurethane Elastomer Through Glycerolysis Route with Using Crude and Refined Glycerine as a Transesterification Agent

Due to the increasing amount of polyurethane waste, chemical recycling of these materials is a topic of growing interest for many researchers. The primary purpose of polyurethane feedstock recycling is to recover the starting polyol. In this study glycerolysis using glycerine from two sources and two purity grades is proposed as a method of chemical recycling. The main effort of this paper focuses on the employment of commercial glycerine of analytical grade and waste glycerine without purification derived from the biodiesel production, as a decomposing agent for polyurethane recycling. In this study, the influence of polyurethane to glycerine mass ratio (PU/GL) and the type of decomposing agent on the chemical structure by FTIR, ¹H NMR and GPC was examined. FTIR analysis of the glycerolysates showed absorption peaks similar to the virgin polyol. Those results are in compliance with GPC chromatograms, which showed for all samples, well-defined peak at ca. 13 min of retention time. The molecular weight of glycerolysates was ranging from 800 to 1300 g mol^?1 depending on PU/GL mass ratio. The novel decomposition agent, namely waste glycerine derived from biodiesel production was successfully used in glycerolysis process.     

Interactive Influence of Biofiber Composition and Elastomer on Physico-Mechanical Properties of PLA Green Composites

The objective of this work was to improve the impact and thermal properties of polylactic acid (PLA)-based biocomposite by appropriate application of cellulosic fiber and a bioelastomer. Biocomposites formulations with fiber contents of up to 20% in combination with a bioelastomer were extrusion-compounded in a twin-screw extruder followed by molding in an injection molding system. Fibers used in the formulations included three types of cellulosic fiber; namely, raw fiber from oat hull biomass (RF), hydrolysis byproduct (ATF) which was the solid fraction obtained from an acid-catalyzed hydrolysis of RF, and delignified fibers (AD30, AD65, AD100) which were the products of delignification of ATF. Formulated biocomposites were characterized for thermal (glass transition and melting temperatures, and enthalpy of melting) and physico-mechanical (tensile and bending strengths, stiffness, impact energy, and water absorption) properties. Among all types of biofibers, RF resulted in poor properties in the biocomposites due to the high hemicellulose content in the structure. On the other hand, the ratio of lignin to cellulose (in the absence of hemicellulose) in the modified fibers did not significantly affect the physico-mechanical and thermal properties of the biocomposites. The elastomer applied in the formulations improved the impact energy, thermal properties, and elongation at break of the composites. However, it adversely affected the strength and water resistance of biocomposites, especially in the presence of hemicellulose. The results indicated that, depending on the application, a wide range of PLA green composites with different physico-mechanical properties can be achieved.     

Degradation Study of Biobased Polyester–Polyurethane and its Nanocomposite Under Natural Soil Burial,UV Radiation and Hydrolytic-Salt Water Circumstances

The current study focuses on the development of a formulation of polyester polyurethane (PEPU) samples using castor oil (CO) modified polyester polyol and partially biobased aliphatic isocyanate. The CO modified polyester polyol was synthesized employing transesterification reaction between CO and diethylene glycol in the presence litharge (PbO) catalyst. Subsequently, the modification of CO was confirmed using proton nuclear magnetic resonance (¹HNMR) spectra analysis. In the next stage, the biobased polyester polyurethane nanocomposites (PEPUNC) were prepared by incorporating 3 wt% OMMT nanoclay within PEPU through in situ polymerization technique. The produced PEPU was confirmed by Fourier transform infrared spectroscopy (FTIR) and ¹HNMR spectra analysis. Further, the degradation properties of developed PEPU subjected to soil-burial, UV exposure and hydrolytic-salt water medium were noted by FTIR spectroscopy. Corresponding weight loss, mechanical measurements and morphological studies through scanning electron microscopy (SEM) analysis were studied. The results showed that the addition of OMMT nanoclay within the PEPU matrix produces significant improvement in the degradation rate which indicated the susceptibility of OMMT nanoclay to humidity upon exposure to soil burial. The produced microorganisms from the soil resulted in significant chemical and morphological changes in the entire structure of the PEPU. Additionally, the highest degradation and percentage of weight loss was observed under soil burial as compared to UV exposure and hydrolytic-salt water medium.     

Simplified Fabrication of Optically Transparent Composites Reinforced with Nanostructured Chitin

Optically transparent films reinforced with micro to nano scale chitin particles were successfully developed in this study. Chitin composites based on micro scale particles which are larger than the optical wavelength do not cause light scattering provided that chitin particles are composed of nano structure networks which allow monomer impregnation and polymerization. This could lead a simplified process for fabricating transparent composites. The composites reinforced by the chitin micro particles not only retained the transparency of the plastic but also helped the effectiveness of its co-efficient of thermal expansion as similar to chitin nanofibers. Furthermore, chitin nanofibers transparent films are thermally stable against temperature as high as 200 °C for a long period of time. This could lead to number of important commercial applications, and is a significant move towards the sustainable utilization of marine bio-resources.     

Biocompatible Polyurethane Scaffolds Prepared from Glycerol Monostearate-Derived Polyester Polyol

Biodegradable polyester polyol was synthesized from oleochemical glycerol monostearate (GMS) and glutaric acid under a non-catalyzed and solvent-free polycondensation method. The chemical structure of GMS-derived polyester polyol (GPP) was elucidated by FTIR, ¹H and ¹³C NMR, and molecular weight of GPP was characterized by GPC. The synthesized GPP with acid value of 3.03 mg KOH/g sample, hydroxyl value of 115.72 mg KOH/g sample and M_n of 1345 g/mol was incorporated with polyethylene glycol (PEG) and polycaprolactone diol (PCL diol) to produce a water-blown porous polyurethane system via one-shot foaming method. The polyurethanes were optimized by evaluating glycerol as a crosslinker, silicone surfactant and water blowing agent on tensile properties of polyurethanes. All polyurethanes underwent structural change, and crystalline hard segments of polyurethanes were shifted to higher temperature suggested that hard segments undergone re-ordering process during enzymatic treatment. In terms of biocompatibility, polyurethane scaffold produced by reacting 100% w/w of GPP with isophorone diisocyanate and additives showed the highest cells viability of 3T3 mouse fibroblast (94%, day 1), and MG63 human osteosarcoma (107%, day 1) and better cell adhesion as compared to reference polyurethane produced by only PEG and PCL diol (3T3 cell viability: 8%; MG63 cell viability: 2%). The current work demonstrated GPP synthesized from renewable and environmental friendly resources produced polyurethanes that allows improvement in physico-chemical, mechanical and biocompatibility properties. By blending with increasing content of GPP, the water-blown porous polyurethane scaffold has shown great potential as biomaterial for soft and hard tissue engineering.     

Biobased Polyurethanes from Rapeseed Oil Polyols: Structure, Mechanical and Thermal Properties

Biobased polyols were synthesized from rapeseed oil (RO) with diethanolamine (DEA), triethanolamine (TEA) and glycerol (GL) at different molar ratios. The structures of the synthesized polyols were analyzed using FTIR-ATR spectroscopy. Polyurethane (PU) networks from RO/DEA polyols and polymeric MDI showed higher tensile strength, modulus and hardness, but their elongation at break decreased, compared to the case of the PU obtained from RO/TEA and RO/GL polyols. The tensile strength and modulus of PU networks increased with increasing PU cohesion energy density (CED) and decreasing molecular weight between crosslinks M _c . From the thermogravimetric analysis and its derivative thermograms, at the first stage of destruction (below 5 % weight loss) in the air and inert atmosphere, the PU obtained from RO polyols were ranked in the following order: PU RO/GL > PU RO/TEA > PU RO/DEA, and their thermostability was higher than that of the PU based on propylene oxide.     

New Multi-Scale Hybrid System Based on Maple Wood Flour and Nano Crystalline Cellulose: Morphological,Mechanical and Physical Study

In the first part of this work, composites based on polypropylene (PP) and maple wood flour (MF) were prepared by melt compounding using twin-screw extrusion followed by compression molding. The morphological and mechanical properties of the composites were analyzed for three samples: PP, MF/PP and MF/PP containing maleic anhydride grafted polypropylene (MAPP) as coupling agent. The results showed that MF/PP composites have improved mechanical properties, especially tensile modulus (+33 %), with only 8 % increase in density. The addition of MAPP further improved the mechanical properties, in particular tensile modulus (up to 51 %), which could be related to better fiber/matrix adhesion. In the second step, nano crystalline cellulose (NCC) was added to all samples to produce NCC-MF/PP hybrid composites. From the mechanical analysis performed, the hybrid composites with MAPP have improved properties, especially tensile (+53 %) and flexural (+40 %) moduli. These results confirmed that multi-scale hybrid NCC-MF composites can substantially improve the mechanical properties of polyolefins with limited increase in density (14 %) leading to high specific properties.     

Laccase-Assisted Grafting of Acrylic Acid onto Lignin for its Recovery from Wastewater

The acrylic acid (AA) in the wastewater from paint manufacturing could be recovered by grafting to lignosulfonate in the presence of laccase and tert-butyl hydroperoxide (t-BHP). The low concentration of t-BHP did not inhibit the laccase activity, but improved the radical formation on lignin by laccase reaction, then initiated AA polymerization on lignin. The results showed laccase took a significant role for AA grafting to lignin. 94 % of AA could be polymerized on lignin by laccase/t-BHP, while only 32 % of AA was grafted on lignin with the same condition without laccase. The ratio of lignin to acrylic acid also affected AA recovery, and higher concentration of acrylic acid led to high recovery rate of AA. In this reaction system, the suitable range of temperature was 30–40 °C for the chemo-enzymatic reaction. The AA grafted on lignin could be precipitated by calcium ion and recovered.