Preparation of liquefied wood-based resins and their application in molding material

To investigate value in use of liquefied wood-based resin applications in molding material, Chinese fir （Cunninghamia lanceolata） and poplar （Populus tomentosa） wood meal were liquefied in phenol. The reactant was co-condensed with formaldehyde to obtain liquefied wood-based resin. For this paper, we investigated the characterization of the resin and its application in molding material. The result shows that the basic properties of liquefied wood-based resin were satisfactory; the bonding strength of plywood prepared with liquefied Chinese fir and liquefied poplar resin can reach 1.54 and 1.00 MPa, respectively. The compression strengths of the molding material prepared with two kinds of liquefied wood resin were 73.01 and 73.58 MPa, almost the same as that of PF resin molding material. The limiting volume swelling of molding material made with liquefied Chinese resin and liquefied poplar resin were 8.5% and 8.3%, thickness swelling rates of water absorption were 3.3% and 4.2%, and the maximum weight ratios of water absorption were 25.9% and 26.2%, respectively. The soil burial test result shows that the weight loss rate of the molding materials made with liquefied Chinese resin and liquefied poplar resin were 8.3% and 9.1% and that of the PF resin molding material was 7.9%. After the soil internment test, the reduction ratio of compression strength of the two kinds of molding material achieved 16.9% and 17.7%, while that of the PF resin molding material was 15.4%. The test results of wood fungi inoculation on the three surfaces of the molding material indicate the breeding rate of molding material prepared with liquefied Chinese resin and liquefied poplar resin were at level 4 and that of PF resin molding material was at level 1 of the ISO standard.     

油茶饼粕苯酚液化物的树脂化研究

以油茶饼粕苯酚液化物为原料制备酚醛树脂,测定树脂的理化性能,评价树脂的胶合性能.考察了甲醛与苯酚的摩尔比(F/P)、氢氧化钠与苯酚的摩尔比(NaOH/P)和树脂化时间对树脂理化性能和胶合性能的影响.结果显示,在F/P 1.8、NaOH/P 0.6、树脂化时间70 min的条件下合成的酚醛树脂压制的胶合板能满足Ⅰ类胶合板强度要求.FTIR分析显示液化物树脂具有常规酚醛树脂典型的官能团特征,树脂中含有较多的羟甲基等活性官能团.     

思茅松的苯酚液化及树脂化研究

研究了硫酸催化条件下,将恩茅松在苯酚中液化用于制备酚醛树脂的技术工艺,分析了各工艺参数对思茅松液化效率的影响,测定了由液化产物制备的液化木基酚醛树脂的物理化学性质和胶合强度。结论如下：1）．液比、反应温度、时间和木粉目数是影响液化反应效率的重要因素,液化产物的残渣率均随上述工艺参数值的升高而降低。2）．残渣含量对树脂物化性质和胶合强度均有影响,残渣含量降低,树脂粘度减小,聚合时间缩短,游离酚含量降低,胶合强度升高。3）．甲醛／苯酚摩尔比对树脂的物化性质和胶合强度也有影响,甲醛／苯酚摩尔比增加,树脂粘度增加,聚合时间减少,游离酚含量减低,胶合强度升高。     

竹材加工剩余物液化及液化产物制备发泡树脂的工艺研究

采用苯酚和聚乙二醇-400复合液化试剂,对竹材加工剩余物进行液化和液化产物的树脂化试验。采用单因素法,探讨主要工艺因素对液化效果及对树脂性能的影响,得到竹材酚醇复合液化工艺及树脂化工艺的优化参数。利用液化产物制备的树脂,可用于制造建筑用发泡材料,提高竹材加工剩余物的附加值。     

人工林木材的苯酚液化及树脂化研究Ⅱ.液化木基酚醛树脂的制备和性能表征

研究液化产物树脂化合成工艺,表征液化木基酚醛树脂的物化性质,评价树脂的胶合强度和木破率.结果表明,采用一次缩聚的投料方式能简化操作工艺,缩短合成时间.木材液化产物中残渣的过滤与否,对树脂性能有一定程度的影响:残渣含量高时,影响较大;残渣含量低时,影响较小.当甲醛与苯酚的量比为1.5和1.8时,利用含11.0%残渣的杉木液化产物和含16.5%残渣的杨木液化产物,制备了性能优良的酚醛树脂.     

杉木粉液化与液化产物树脂化的研究

以硫酸为催化剂、苯酚为液化剂采用溶剂热法对杉木粉进行液化,用杉木粉液化产物制备出酚醛树脂;考察了反应温度、反应时间、液比(苯酚-木粉的质量比)和催化剂用量对杉木粉液化效率的影响,并初步探讨了液化产物残渣率对所制酚醛树脂性能的影响。实验结果表明,杉木粉液化的最佳工艺条件是:反应温度160℃,液化时间12 h,液比值3,催化剂用量3%,在此条件下残渣率约为10%。液化产物残渣率的测定表明,升高反应温度、延长反应时间、增加液比和催化剂用量可以降低残渣率,提高液化效率;液比值为0.5~1.5时残渣率随液比增加而显著降低,催化剂用量为0.5%~2%时液化效率的变化明显。红外光谱结果表明,由液化产物所合成的酚醛树脂中羟甲基含量较高。液化产物残渣率低时制备的酚醛树脂残碳率较高。     

不同物质的量之比乙二醛⁃尿素⁃甲醛共缩聚树脂的合成与性能

为了降低木材胶黏剂中的甲醛含量,减小胶合板甲醛释放对人体健康和环境造成的危害,采用乙二醛与单羟甲基脲(MMU)反应,合成了MMU与乙二醛物质的量之比分别为0.7∶1.0,0.9∶1.0,1.1∶1.0和1.3∶1.0的乙二醛?尿素?甲醛(GUF)共缩聚树脂;采用傅里叶变换红外光谱(FT?IR)和X射线衍射(XRD)对树脂的结构进行了表征,对树脂的基本性能、固化性能、润湿性能及胶合性能进行测定,并进行对比分析。结果表明,合成制备的GUF树脂稳定性较好,均超过了10 d;外观均为酒红色均一液体。MMU与乙二醛的物质的量之比对树脂固体含量和黏度有较大影响,固体含量随着物质的量之比增大而增大,当MMU与乙二醛物质的量之比为1.3∶1.0时,树脂的固体含量为63.12%;当MMU与乙二醛物质的量之比为0.9∶1.0时,树脂黏度的最小值为23.91 mPa·s。树脂的主要官能团(N—H、O—H、C??O、C—O—C和C—N)的红外吸收峰基本不受物质的量之比的影响。树脂对杨木单板的润湿性能良好,接触角为50.8°~57.3°;MMU与乙二醛的物质的量之比为1.3∶1.0时合成的GUF树脂性能较优,胶合板干状胶合强度和湿强度分别为1.81和1.47 MPa;低物质的量之比的GUF树脂固化后会出现晶体结构。     

PMUF树脂胶黏剂的制备与性能

以尿素和三聚氰胺作为酚醛树脂改性单体制备苯酚-三聚氰胺-尿素-甲醛(PMUF)树脂胶黏剂,研究甲醛、苯酚、尿素、三聚氰胺及氢氧化钠用量对PMUF树脂胶黏剂性能的影响,并采用DSC和13C-NMR对其进行表征.结果表明:PMUF树脂游离甲醛含量低,能满足耐水、耐候性能要求较高的人造板产品的生产.当甲醛、苯酚、尿素、三聚氰胺、NaOH的摩尔比为3.1∶1∶0.7∶0.3∶0.5时胶黏剂性能最佳,其最佳固化温度为135.5℃.     

杉木液化产物制备环保型PF树脂的研究

用硫酸和苯酚将杉木液化,采用傅立叶变换红外光谱和凝胶渗透色谱技术对液化产物进行了分析,并对用液化产物代替苯酚制备PF树脂的工艺进行了探讨。研究结果表明:杉木液化产物中含有大量的具有苯环结构的小分子活性物质,分子量主要分布在800～2 300之2;原料配比、树脂化温度、升温方式和残渣率等因素对PF树脂的质量有明显影响,采用优化工艺制备的PF树脂的游离酚和游离醛的含量分别为0.5%和0.3%,且胶合性能优良。     

Preparation of phenol formaldehyde resin from phenolated wood

The technique for preparing phenol formaldehyde resin from phenolated wood (PWF) and its characters were studied and analyzed. Poplar (Populus spp) wood meal was liquefied by phenol in the presence of sulfuric acid as a catalyst. After the liquefied products were cooled, alkaline catalyst and formaldehyde were added. The mixture was kept at (60±2)°C for 1h and then was heated to (85±2)°C for 1h. The influence of molar ratio of formaldehyde to phenol (F/P) was investigated. The results showed when the molar ratio of formaldehyde to phenol was over 1.8, the PWF adhesives had high bond quality, bond durability and extremely low aldehydes emissions. Foundation item: The research was supported by Sino-Japanese Technical Cooperation Project (2-1-b) and the key technologies R & D Program for the 10th Five-Year Plan (325-11). Biography: LI Gai-yun (1974-), female, Assistant professor in Research Institute of Wood Industry, Chinese Academy of Forestry, Beijing 100091, P. R. China Responsible editor: Zhu Hong     

用酚化木材制备酚醛树脂的研究

本文研究了用酚化木材制备酚醛树脂的技术,并对其性能进行分析。在硫酸催化作用下,用苯酚对中国人工林杨树木粉进行液化。待液化产物冷却后,加入一定量的碱性催化剂和福尔马林,在(60?2)C下1小时,然后升温至(85?2)C继续反应1小时,冷却。同时观察了甲醛与苯酚的配比对树脂性能的影响。结果表明当甲醛与苯酚的摩尔比超过1.8时,用酚化木材制备的酚醛树脂具备较高的胶合强度和很强的胶合耐久性,并具有极低的醛类释放量。图4参13。     

Effects of phosphoric acid on liquefaction of wood in phenol and optimum liquefaction processing parameters

To clarify the influencing factors of liquefaction of wood in phenol using phosphoric acid as a catalyst and get its liquefaction technology, a study on the liquefaction technology of Chinese fir (Cunninghamia lanceolata) and poplar (triploid Populus tomentosa Carr) under different conditions was conducted. The results indicate that the residue rate decreases with the increase of liquefaction temperature, liquefaction time, catalyst content or liquid ratio. It is also found that the optimum condition of liquefaction for poplar is estimated as: the reaction temperature of 180 ℃, the reaction time of 2.5 h, liquid ratio (phenol/wood ratio)of 4.5 and catalyst content of 8%, and 4.2% residue rate could be obtained. Under the processing parameters of temperature 180 ℃, the reaction time of 2.5 h, liquid ratio (phenol/wood ratio) of 4 and catalyst content of 10%, the residue rate of Chinese fir can reach 5.6%.     

Dynamic wettability and curing characteristics of liquefied bark-modified phenol formaldehyde resin (BPF) on rice straw surfaces

Larch bark was liquefied in the presence of phenol and the obtained liquefied resultant was reacted with formaldehyde to prepare the liquefied bark-modified phenol formaldehyde resin (BPF) in an attempt to apply for preparing straw boards. The dynamic wettability of the BPF resin was evaluated on the surfaces of rice straw; either on the alkali solution treated or untreated rice straw surfaces. A new wetting model was employed to quantify the resins’ penetration performances using the spreading–penetration parameters (K value) as a constant to characterize penetration rate. The bigger the K value was, the stronger the penetration and spreading capacity was. Moreover, the curing kinetics of the BPF resin was also investigated with dynamic differential scanning calorimetry. The results showed that the K value of BPF resin was the highest, followed by those of BPF mixed with polymethylene diphenyl diisocyanate PMDI resin and conventional phenol formaldehyde (PF) resin, indicating that the BPF resin had the best wettability. The activation energy of BPF was close to that reported for wood/phenol/formaldehyde resins, but was higher than that of PF resin. The curing reaction was almost complete at 40 % conversion.     

C NMR 定量分析

按酚醛(PF)树脂的制备工艺,采用CaO和NaOH为复合催化剂,在碱性条件下制备了95%～200%的系列尿素改性酚醛(PUF)树脂,贮存期达30 d以上。该系列PUF树脂压制的杨木三合板,胶合强度符合Ⅱ类胶合板要求,甲醛释放量<0.5 mg/L,符合E0级。其中选用尿素/苯酚(U/P)质量比为1.5∶1,甲醛与尿素-苯酚(F/(U+P))物质的量的比值为0.97的配方制胶,结合13C NMR分析手段,监控投料甲醛在反应过程中形成的亚甲基、羟甲基和亚甲基醚键的含量变化,以及最终PUF树脂的亚甲基(32.4%)、羟甲基(57%)和亚甲基醚键(10%)的结构比例。     

等离子体改性热塑性树脂薄膜制备环保胶合板试验

为获得无甲醛释放的环保胶合板,将热塑性树脂薄膜(低密度聚乙烯(LLDPE)、聚丙烯(PP)、聚氯乙烯(PVC))用作胶黏剂,并利用空气介质阻挡等离子体对热塑性树脂薄膜进行表面改性处理以提高薄膜与杨木单板的界面相容性,从而获得性能良好的环保胶合板。研究了等离子体处理对胶合板胶合性能的影响,并从等离子体处理对热塑性树脂薄膜表面化学组分及其对胶合板界面形貌的影响分析其胶合机理。结果表明:在等离子体处理功率为4.5 kW、处理时间为8 m/min的条件下处理热塑性树脂薄膜,胶合板的胶合强度得到显著提高,LLDPE/杨木胶合板的胶合强度从0.49 MPa增至0.81 MPa,PP/杨木胶合板的胶合强度从0.65 MPa提高到0.84 MPa,均达到Ⅱ类胶合板标准要求。其中用等离子体处理后PVC与杨木制备的胶合板能满足Ⅰ类胶合板的标准要求,胶合强度达到0.79 MPa。XPS分析表明,等离子体改性热塑性树脂薄膜的表面发生了氧化反应,引入了含氧官能团,提高了薄膜表面极性,有利于提高薄膜与杨木单板之间的相互作用,从而使得胶合板的界面胶合更为紧密,说明等离子体处理后树脂与杨木单板的相容性提高,树脂能在单板表面更好地附着。热塑性树脂薄膜与杨木单板制备的胶合板仅有极微量甲醛释放,其主要源于木材自身,远低于国家标准对人造板甲醛释放限量的要求。研究证明等离子体处理能明显改善热塑性树脂薄膜与杨木单板的界面相容性。     

Curing behavior and adhesion properties of epoxy resin blended with polyhydric alcohol-liquefied <Emphasis Type="Italic">Cryptomeria japonica</Emphasis> wood

Cryptomeria japonica (Japanese cedar) wood was liquefied using polyethylene glycol (PEG-400 and PEG-600)/glycerol as the solvent with H₂SO₄ as a catalyst. The blended epoxy resins were prepared by mixing the liquefied wood with epoxy resin of various weight ratios and used for wood gluing. The results showed that blended epoxy resins could cure under room temperature with an exothermic reaction. DSC thermoanalysis showed that increasing the blending amount of liquefied wood would shift the peak of curing reaction to a higher temperature but with less heat released. Blended epoxy resins had a good dry bonding strength for wood when cured at room temperature. However, curing with heat treatment could improve the wet bonding strength of blended epoxy resins, especially for those prepared with PEG-400-liquefied wood.     

Properties of Wood/Montmorillonite Nanocomposites

INTRODUCTIONWood possesses many special properties, such asbeautiful grain, natural color, high strength-to-weightratio, good electricity and heat insulation; and it can beeasily processed, glued or dyed. It is biodegradable,recyclable and environmental-friendly (Wang Tianminet al. 2002). But as a biomaterial, it also has intrinsicdefects as easy decaying, burning and deforming,which largely limits its usage. Nano science andtechnology opens a completely new way to developwood composites…     

Rapid wood liquefaction by supercritical phenol

Wood was rapidly liquefied at the supercritical temperature of phenol. Under these conditions, wood was liquefied by over 90% for 0.5 min, and the combined phenol content of the obtained liquefied wood reached about 75%. The effects of various reaction conditions on liquefaction were investigated. With increases in reaction temperature, phenol/wood weight ratio, and the charged mass-to-reactor capacity (w/v) ratio, the amount of methanol-insoluble residue decreased and combined phenol content increased. The range of molecular weights and polydispersity of the products obtained after the time at which sufficient liquefaction was achieved were from 400 to 600 and from 1.5 to 2.5, respectively. Wood showed a marked decomposition to low molecular weight components early in the reaction, and then the molecular weight increased slightly with increasing reaction time. The properties of liquefied wood were investigated and compared with those obtained with conventional liquefaction methods. Combined phenol content was similar to that obtained by other liquefaction methods, except the sulfuric acid–catalyzed method, which resulted in flow properties comparable to those of other liquefaction methods. The flexural strength of moldings prepared using liquefied wood was also comparable to those prepared by other liquefaction methods.     

Liquefaction and product identification of main chemical compositions of wood in phenol

To clarify liquefaction ratios and their construction variations of the main chemical compositions of wood in phenol using phosphoric acid as a catalyst, the chemical ingredients of wood such as holocellulose, cellulose and lignin, were measured and extracted according to GB methods. With Fourier transform infrared （FTIR）, the product identification of reactant before and after liquefaction in phenol was investigated. The molecular weights and their distributions of the liquefaction results （acetone soluble parts） were studied by gel permeation chromatography （GPC）. Results show that the molecular weights and their distributions of poplar and Chinese fir are almost the same. In poplar, the distribution of cellulose is the largest, and that ofholocellulose the smallest after liquefaction. For Chinese fir, the distribution of holocellulose is the largest, and that of cellulose the smallest. After liquefaction of poplar cellulose, the change bands of FTIR spectrum observed below 1 600 cm^-1, can be attributed to new substitute groups. The same is true for poplar lignin. For Chinese fir, the spectra of liquefaction results of all chemical compositions differ from that of wood meal. This reveals the more activity groups were produced because of the reactions between Chinese fir and phenol. The research shows that the liquefaction ratios of poplar decrease in the following order： holocellulose 〉 lignin 〉 cellulose, and those of Chinese fir in the order： lignin 〉 cellulose 〉 holocellulose.     

高支化聚脲对脲醛树脂胶黏剂耐水性能和甲醛释放量的影响

引入高分子量、高支化度以及端基为尿素的高支化聚脲(HBPU)用于低摩尔比脲醛树脂(UF)改性,利用HBPU与游离甲醛的反应以及与UF组分的共缩聚反应实现树脂耐水性能的提升和人造板甲醛释放量的降低,有效平衡胶合性能和甲醛释放量之间的矛盾。在无溶剂、无催化剂条件下,通过尿素(U)与三(2-氨基乙基)胺(TAEA)的脱氨缩合反应,一步合成了具有尿素端基的HBPU,并对HBPU的分子量分布和结构进行了表征。使用HBPU水溶液,采用UF合成反应后期加入和共混2种方法对UF进行改性,通过胶合板性能测试以及甲醛释放量测定,考察了HBPU添加量和添加方式的影响。凝胶渗透色谱和碳-13核磁共振分析表明,通过本研究的合成方法可以获得具有高分子量、高支化度、尿素为端基且水溶性良好的HBPU,并且随着U与TAEA摩尔比的提高,更多尿素封端产物形成。电喷雾电离质谱对改性树脂的分析结果表明,HBPU不仅与UF中的一部分游离甲醛发生羟甲基化反应,同时与UF组分反应生成了部分共缩聚产物。胶合板性能测试结果表明,共混以及反应后期加入HBPU两种方式得到的改性树脂耐水性能均显著提升。同时,使用添加5%HBPU改性树脂制备...