Ionic liquid modified lignin-phenol-glyoxal resin: a green alternative resin for production of particleboards

The aim of this research was to evaluate the properties of particleboard panels bonded with ionic liquid treated lignin- phenol- glyoxal (LPG) resin. For this purpose, soda bagasse lignin was modified by 1-ethyl-3-methylimidazolium acetate ([Emim][OAc]) ionic liquid and then various contents of virgin and modified lignin (20, 30 and 40 wt% based on weight of phenol), phenol and glyoxal were used for synthesis of LPG resins. After resin synthesis, thermal and physicochemical properties of the synthesized resins such as curing behavior, gelation time, viscosity, solid content and density were measured. Finally, the resins so prepared were used for laboratory particleboard manufacturing. The panels physical (water absorption, thickness swelling) as well as mechanical (MOE, MOR and internal bond strength) properties were measured according to standard methods. The resins tests indicated that modification of lignin with ionic liquid not only can accelerate the gelation time and increase viscosity, density and solid content of LPG resins but also decrease the temperature required for curing the LPG resins. Based on the results of this work, the mechanical strength and dimensional stability of the particleboards bonded with a LPG resin can be improved by using modified lignin. The particleboards prepared with the LPG resin, using either modified or virgin lignin, presented higher water absorption as well as weaker mechanical strength than those prepared with the control PF resin. However, there does not appear to be any statistically significant difference between the some properties of the panels bonded with the control PF resin and those bonded with the LPG resin containing modified lignin.     

木质素改性脲醛树脂胶粘剂合成工艺及性能研究

以木质素作为改性剂,采用正交试验法探讨了n(甲醛)∶n(尿素)、木质素加入量和木质素加入时间对UF(脲醛树脂)胶粘剂的游离甲醛含量和胶接强度的影响,并优选出制备改性UF胶粘剂的最佳工艺条件。结果表明:当n(F)∶n(U)=1.6∶1、w(木质素)=40%(相对于尿素质量而言)和前期加入木质素时,UF胶粘剂的游离甲醛含量(0.052 8%)满足室内装饰装修材料用胶粘剂中有害物质限量要求(GB 18583—2001)、胶接强度为6.65 MPa且耐水性明显提高。     

Improving the properties of ionic liquid-treated lignin-urea-formaldehyde resins by a small addition of isocyanate for wood adhesive

The aim of this research was to investigate the effect of polymeric 4, 4 diphenyl methane diisocyanate (pMDI) on the physical and mechanical properties of plywood panels bonded with an ionic liquid (IL)-treated lignin-urea-formaldehyde resin. Soda lignin modified by 1-ethyl-3-methylimidazolium acetate ([Emim][OAc]) IL was added to a urea formaldehyde (UF) resin during resin synthesis to prepare a lignin-urea-formaldehyde (LUF) resin. pMDI at various contents (2, 4, and 6% on resin solids) was then added to prepare a LUF resin. The thermal and physicochemical properties of the resins prepared as well as the water absorption, shear strength, and formaldehyde emission of the plywood panels bonded with them were measured according to standard methods. DSC analysis indicated that the addition of pMDI decreases the gel onset and curing temperatures of the LUF resin. According to the results obtained, the addition of pMDI significantly increased the viscosity and solid content and accelerated the gelation time of LUF resins. Based on the findings of this research, the addition of pMDI dramatically improves the performance of LUF resins as a new adhesive for wood-based panels. The LUF resins with isocyanate added yielded panels presenting lower formaldehyde emission and lower water absorption content when compared to those bonded with the control LUF resins. Greater dry and wet shear strength can be obtained by a small addition of pMDI to LUF resins.     

Influence of nanoclay on urea–glyoxalated lignin–formaldehyde resins for wood adhesive

In this research, the influence of nanoclay on urea–glyoxalated lignin–formaldehyde (GLUF) resin properties has been investigated. To prepare the GLUF resin, glyoxalated soda baggase lignin (15 wt%) was added as an alternative for the second urea during the UF resin synthesis. The prepared GLUF resin was mixed with the 0.5%, 1%, and 1.5% nanoclay by mechanically stirring for 5 min at room temperature. The physicochemical properties of the prepared resins were measured according to standard methods. Then the resins were used in particleboard production and the physical and mechanical properties of the manufactured panels were determined. Finally, from the results obtained, the best prepared resin was selected and its properties were analyzed by differential scanning calorimetry (DSC), Fourier transform infrared spectrometry (FTIR), and X-ray diffractometry (XRD). Generally the results indicated that the addition of sodium-montmorillonite (NaMMT) up to 1.5% appears to improve the performance of GLUF resins in particleboards. The results also showed that nanoclays improved mechanical strength (modulus of elasticity (MOE), Modulus of Rupture (MOR), and internal bond (IB) strength) of the panels bonded with GLUF resins. The panels containing GLUF resin and nanoclay yielded lower formaldehyde emission as well as water absorption content than those made from the neat GLUF resins. XRD characterization indicated that NaMMT only intercalated when mixed with GLUF resin. Based on DSC results, the addition of NaMMT could accelerate the curing of GLUF resins. The enthalpy of the cure reaction (ΔH) of GLUF resin containing NaMMT was increased compared with neat GLUF resin. Also the results of FTIR analysis indicated that addition of NaMMT change the GLUF resins structures.     

The effect of soda bagasse lignin modified by ionic liquids on properties of the urea–formaldehyde resin as a wood adhesive

The aim of this research was to investigate the influence of lignin modified by ionic liquids on physical and mechanical properties of plywood panels bonded with the urea–formaldehyde (UF) resin. For this purpose, soda bagasse lignin was modified by the 1-ethyl-3-methylimidazolium acetate ([Emim][OAc]) ionic liquid and then the various contents of unmodified and modified lignins (10, 15, and 20%) were added at pH=7 instead of second urea during the UF resin synthesis. The physicochemical properties of the prepared resins as well as the water absorption, shear strength, and formaldehyde emission of the plywood panels made with these adhesives were measured according to standard methods. According to Fourier Transform Infrared (FTIR) Spectrometry, by treatment of lignin, the C=O, C–C, and C–H bonds decrease while the content of the C–N bond dramatically increases. Based on the finding of this research, the performance of soda bagasse lignin in UF resins dramatically improves by modification by ILs; as the resins with modified lignin yielded lower formaldehyde emission and water absorption when compared to those made from unmodified lignin and commercial UF adhesives, respectively. The shear strength as well as wood failure percentages are lower for the panels produced with modified lignin than for the panels produced with UF resins alone.     

微波辅助离子液体EmimOAc提取毛竹木质素

毛竹细胞壁强的抗解构特性大大限制了毛竹作为原料在生物质能源、生物质基材料等领域的应用,因此有必要对其进行包括主要组分分离在内的预处理以提高它的使用效率。本研究采用微波辅助1-乙基-3-甲基咪唑乙酸盐（EmimOAc）法从毛竹中分离出木质素,分析所获得的木质素的物理化学特性,并与用5% NaOH（50℃,5h）提取的毛竹木质素、油浴加热（110℃,16h）EmimOAc提取的毛竹木质素进行对比。结果表明：微波辅助EmimOAc处理80min后木质素得率14.7%,比油浴加热EmimOAc提取木质素的得率（6.2%）提高了2倍以上;离子液体提取的木质素（ILL）和碱提木质素（AL）具有相似骨架结构,但在离子液体的作用下,ILL结构中有更多的酯键链接发生断裂;与AL相比,ILL具有更高的热稳定性。     

离子液体中木质素的酯化及其对环氧树脂的改性

以麦草醇解木质素为原料,丁二酸酐(SA)为酯化剂,1-丁基-3-甲基咪唑氯盐离子液体为反应介质,在不添加其他反应助剂和催化剂的条件下,对木质素进行酯化改性,制备了酯化木质素。研究了温度、时间、n(SA)/n(—OH)等对酯化木质素接枝率的影响,并探讨了酯化木质素对环氧树脂(EP)热稳定性、耐热性能、弯曲应力及黏接性能的影响。结果表明:酯化木质素的接枝率随n(SA)/n(—OH)增大而提高,当酯化反应在80℃持续2.0 h时,接枝率高达68%;酯化木质素中出现明显的酯基特征峰,且其热稳定性得到改善;加入酯化木质素使EP的热稳定性得到改善,维卡软化温度提高近5.0℃,弯曲应力和拉伸剪切强度均有所增加。     

离子液体[BMIm]Cl中H_2O_2改性碱木质素的结构及热稳定性

采用等体积质量分数30%的H2O2溶液和离子液体[BMIm]Cl的混合液对提取自造纸黑液的碱木质素氧化改性后,清液加水再生,所得氧化改性碱木质素结构上发生解聚和活化,热稳定性显著降低。FT-IR分析表明,改性后碱木质素发生了部分解聚并仍保留着木质素的主要官能团结构,且邻位二取代酚类结构含量增多;XRD分析表明,改性后杂质盐被脱除,晶体衍射强度减弱,碱木质素解聚使有机结构复杂性增强,其紫丁香基结构经氧化降解产物类似2,6-二羟基苯甲酸结构;由SEM分析可知,碱木质素团聚结构由氧化改性前的杂乱紧簇晶体状转变为改性后较为规则的层状叠加结构,颗粒粒径则大幅减小。而TG/DTG/DTA分析发现氧化改性后的碱木质素热分解温区收窄为533—649 K,最大分解速率加快1倍,969 K时总质量损失率上升约15%。研究表明,经离子液体[BMIm]Cl中H2O2氧化改性后的碱木质素,降低了其在材料合成和热解制备化学品的工艺操作条件,可进一步拓展其在化工产品中的应用。     

离子液体与树脂催化合成醋酸正丁酯的动力学比较

以阳离子交换树脂AMBERLYST15和各种离子液体为催化剂,研究了醋酸和正丁醇反应生成醋酸正丁酯的动力学。实验测定了催化剂种类、反应温度和催化剂量对反应速率的影响,并用拟均相模型对实验数据拟合。在实验条件下,发现AMBERLYST15和己内酰胺四氟硼酸盐催化效率很高,表观活化能分别为36.69,37.06kJ/g,指前因子分别为120.0,61.50m3/(g.h)。结果表明,树脂AMBERLYST15和己内酰胺四氟硼酸盐离子液体二类催化反应的活化能相近,指前因子却相差很大,2种催化剂在相同的催化机理下有不同的催化效率。     

脲醛改性酶解木质素对丁苯橡胶阻燃性能的影响

以脲醛改性酶解木质素配合自制的微胶囊红磷(MRP)制得高分子膨胀阻燃剂,用傅里叶变换红外光谱和差示扫描量热法对其进行了表征,并将其添加到丁苯橡胶(SBR)中,研究了SBR的阻燃性能和力学性能。结果表明,脲醛改性酶解木质素在280℃附近出现了1个较强的吸热峰;随着改性酶解木质素或MRP用量的增加,SBR的阻燃性能提高;当改性酶解木质素用量为60份、MRP用量为10份时,或当改性酶解木质素用量为40份、MRP为12份时,SBR的阻燃级别均可达到FV-0级;SBR/改性酶解木质素/MRP共混物的燃烧残渣表面生成了连续而致密的炭层,孔洞很少且细小。当改性酶解木质素用量为40份时,SBR硫化胶具有最佳的拉伸性能;当MRP用量为10份时,SBR硫化胶的综合性能较好。     

质量连接性指数改进的基团贡献法预测咪唑类离子液体的熔点

离子液体（ILs）由于其优越的性能目前已成为多个领域的研究热点,但热力学基础数据的缺乏是其应用的障碍之一,除实验测定外,基团贡献等思想也为设计和筛选ILs提供了重要的性质预测方法。采用相对简单的质量连接性指数区分ILs不同基团的连接方式,在考虑离子液体的结构特征基础上利用相对成熟的基团贡献思想,建立了一个新的基团贡献模型用于预测咪唑类ILs的熔点。对121种咪唑类ILs熔点的预测结果的平均相对偏差为5.15%,方差检验所得的R2和RMSD分别为0.8686和相似文献   

Separation and recovery of cellulose and lignin using ionic liquids: a process for recovery from paper‐based waste

BACKGROUND: The production of paper makes use of cellulose and lignin as a raw material, and almost all cellulose and lignin production comes from raw wood materials, contributing to deforestation and resulting in potential environmental harm. It is therefore beneficial to develop technologies for cellulose and lignin recovery for re‐use and sustainability of resources. RESULTS: Three imidazolium based ionic liquids (ILs), 1‐(2‐cyanoethyl)‐3‐methylimidazolium bromide (cyanoMIMBr), 1‐propyl‐3‐methylimidazolium bromide (propylMIMBr) and 1‐butyl‐3‐methylimidazolium chloride (butylMIMCl), were synthesised by microwave technology and fully characterised by mass spectrometry, thermogravimetric differential scanning calorimetry, thin layer chromatography, nuclear magnetic resonance and Fourier transform infrared spectroscopies. Cellulose and lignin were soluble in all three ILs with solubility being greatest in cyanoMIMBr. Regeneration of cellulose and lignin was achieved from saturated solutions of cellulose in IL and lignin in IL for all three ILs. The ILs propylMIMBr and butylMIMBr have been used for the first time in the separation and recovery of cellulose and lignin and regeneration of the IL from a mixture of cellulose and lignin in IL. FTIR analysis confirms successful recovery. CONCLUSIONS: This work demonstrates the ability of ILs to separate and recover cellulose and lignin from a mixed system. Copyright © 2009 Society of Chemical Industry     

Development and characterization of a wood adhesive using bagasse lignin

Bagasse is spent fiber left after extraction of sugar. It is mainly used as a fuel to concentrate sugarcane juice. In the present work, the possibility of preparing wood adhesives from bagasse has been explored. The parameters for the preparation of a lignin phenol formaldehyde (LPF) adhesive, (lignin concentration, formaldehyde to phenol molar ratio, catalyst concentration, reaction time and reaction temperature) have been optimized. It was found that up to 50% of phenol can be substituted by bagasse lignin to give LPF wood adhesive having better bonding strength in comparison to a control phenol formaldehyde (CPF) wood adhesive. Prepared resins were characterized using IR, DSC and TGA. IR spectra of LPF resin showed structural similarity with CPF resin. Thermal stability of LPF resin was found to be lower as compared to CPF resin. DSC studies reveal a lower curing temperature for LPF adhesive in comparison to CPF adhesive. A shelf-life study reveals that LPF exhibits consistent behavior as compared to CPF in respect to adhesive strength.     

Hydrolysis reaction of poly(ethylene terephthalate) using ionic liquids as solvent and catalyst

The hydrolysis of poly(ethylene terephthalate) (PET) was studied using ionic liquid 1‐n‐butyl‐3‐methylimidazolium chloride ([Bmim][Cl]) as solvent and acid‐functionalized ionic liquid 1‐methyl‐3‐(3‐sulfopropyl)‐imidazolium hydrogen sulfate ([HSOpmim][HSO₄]) as catalyst. The effects of temperature, time, and dosages of solvent and catalyst on hydrolysis results were examined. Under the optimum conditions of m(PET) : m(H₂O) : m([Bmim][Cl]) : m([HSOpmim][HSO₄]) = 3 : 4 : 6 : 0.6, reaction temperature 170°C and time 4.5 h, the conversion of PET and the yield of terephthalic acid (TPA) were almost 100% and ≥88%, respectively. After easily separated from the product, the ionic liquids could be reused eight times without obvious decrease in the conversion of PET and yield of TPA. Hence, an environmental friendly strategy for chemical recycling of PET was developed. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

氯铝酸型离子液体催化烷基化的研究进展及工业化前景

总结了近20年来国内外在氯铝酸型离子液体的酸性表征和烷基化催化方面的研究,在综述了大量实验室研究工作的基础上,结合少数中试研究讨论了氯铝酸型离子液体的工业化应用前景。     

红外光谱与热重分析法研究腐植酸改性脲醛树脂

将腐植酸(HA)进行羟甲基化改性,然后按照m(HA羟甲基化溶液)∶m[脲醛树脂(UF)]=1∶4比例将两者混合均匀,制得腐植酸-脲醛树脂(HUF)。采用红外光谱(FT-IR)、热重分析(TGA)及差示扫描量热(DSC)法等对UF和HUF的结构、热稳定性及玻璃化转变温度(Tg)等进行表征。结果表明:HUF与UF的FT-IR曲线基本相同,前者的FT-IR特征峰均有不同程度增强,热失重峰向高温区移动,说明HUF既保留了UF的原有结构,又具有较强的耐热性;当w(改性HA)=5%～30%时,HUF胶粘剂的胶接强度相对较大;与未改性UF相比,HUF价格更低(节约350元/t)、更环保(甲醛释放量达到GB 18 580-2001标准中E1级指标要求),故HUF具有较强的市场竞争力和良好的应用前景。     

Evaluation and mechanism of cationic/anionic dyes extraction from water by ionic liquids

Dispersive liquid–liquid micro-extraction (DLLME) using three different imidazolium-based ionic liquid (IL) was applied for extraction of recalcitrant dyes, Eriochrome black T (anionic azo dye), and Crystal Violet (cationic triphenylmethane dye) from aqueous solutions, not previously reported. Effects of process parameters such as initial dye concentration, pH of aqueous phase, amount and type of IL on fraction extracted, and distribution ratio of dyes were studied. Further, dyes interaction with ILs and extraction mechanism were explored. Considering the high cost of ILs, regeneration and reuse study for ILs was also performed using reverse DLLME. The fraction extracted for both the dyes with all the ILs varied significantly with pH change. Maximum dyes fraction extracted were observed nearly at neutral pH (pH =7). However, the fraction extracted were different for different IL.     

离子液体中固体酸催化合成四氢呋喃和四氢吡喃衍生物

在固体酸SO4^2-／SnO2—Fe2O3或S2O8^2-／SnO2-Fe2O3或钨磷酸（H3PW12O40）催化下，由离子液体介质中不饱和醇出发，以高收率制得四氢呋喃和四氢吡喃衍生物。讨论了硫酸、对甲基苯磺酸、三氟甲基磺酸、固体酸SO4^2-／SnO2-Fe2O3或S2O8^2-／SnO2-Fe2O3或钨磷酸对反应转化率的影响。结果表明，在固体酸和离子液体催化体系中，利用不饱和醇成功地制得了四氢呋喃和四氢吡喃衍生物，收率达到90％以上，且反应体系可循环使用。     

Performances of larch (larix gmelini) tannin modified urea–formaldehyde (TUF) resin and plywood bonded by TUF resin

Tannin from larch (Larix gmelini) bark extracts, as a natural renewable resource, was used to prepare tannin–urea–formaldehyde (TUF) resin. The chemical structures of larch tannin and TUF resin were characterized by matrix‐assisted laser desorption/ionization‐time of flight mass spectrometry and ¹³C nuclear magnetic resonance. The thermal behaviors of TUF resin were evaluated by differential scanning calorimetry (DSC) and thermomechanical analysis (TMA). The performances of TUF resin were investigated by measuring the bond strength and formaldehyde emission of its bonded plywood. It was clearly shown that larch tannin is mainly composed of prodelphinidin repeating units. Phenolic groups were introduced into TUF resin mainly linked by methylene bond. Larch tannin has an adverse effect on the resin curing. However, it promoted the rigidity and flexibility of the glued system and upgraded the properties of plywood. Therefore, larch tannin could be applied in the modification of urea–formaldehyde resin. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41064.