Factors affecting the resinification of liquefied phenolated wood

Wood of Chinese fir and poplar were liquefied in phenol at 150℃ and atmospheric pressure. The liquefied wood were reacted with formaldehyde to synthesize the liquefied wood-based resin. The factors affecting the resinification and the properties of new resin were investigated. The results show that the formaldehyde/liquefied wood molar ratio, reaction temperature, reaction time and sodium hydroxide/liquefied wood molar ratio have important influence on the resin characteristics. With the increase of formaldehyde/liquefied wood molar ratio, the yield of resin increases, and the flee phenol content of resins decreases, showing that the resinification of liquefied wood is more complete at higher formaldehyde/liquefied wood molar ratios. The reaction temperature on the viscosity of the liquefied resin has considerable effect; the viscosity of resin increased with increasing reaction temperature, and the amount of liquefied poplar resin increased more quickly than that of liquefied Chinese fir resin. The resinification time also has obvious influence on the viscosity of resin; the viscosity of liquefied poplar resin is more sensitive to resinification time compared with that of liquefied Chinese fir. The amount of sodium hydroxide can improve the water miscibility of liquefied wood resin. The optimum sodium hydroxide/liquefied wood molar ratio for preparation of liquefied wood-based resins exceeds 0.4.     

Properties of wheat straw particleboards bonded with different types of resin

Wheat straw particleboard bonded with a urea–formaldehyde (UF) resin, usually employed in the manufacture of wood-based particleboards, or with a resin based on epoxidised oil was manufactured using a compression molding machine. The effects of resin type on internal bond strength, flexural modulus, and thickness swelling were examined. The properties of boards using UF resins were poor. Internal bond strength and thickness swelling, linked to adhesion quality, were especially low. The high compatibility between straw particles and oil-based resin was explained in terms of straw surface free energy. In straw, this parameter exhibits a much lower polar component than wood species and leads to higher compatibility with resins based on oil than with water-soluble systems like UF.     

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.     

Determination of melamine content in amino resins by near-infrared spectroscopy

Melamine-urea-formaldehyde resin production has increased in the last years due to low formaldehyde emissions and improved moisture resistance when applied on wood-based panels. Melamine is a relatively high-cost raw material in the resin formulation and has a significant effect on wood-based panel properties. It is important for industry to implement efficient quality control methods to determine melamine content in resins. The main objective of this work was to develop chemometric techniques for off-line monitoring of melamine content using near-infrared spectroscopy. The use of interval partial least squares regression allowed identifying the most interesting spectral ranges for analysis (4,400–4,800 and 5,200–5,600 cm^?1) and the best preprocessing methods to use in the determination of this property. When the appropriate spectral range and preprocessing methods are selected, it is possible to obtain calibration models with high correlation coefficients.     

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。     

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。     

三聚氰胺树脂性能变化的研究

对人造板饰面过程中常用的三聚氰胺树脂在贮存和使用过程中性能的变化进行了测定。确定了树脂的性能变化趋势、贮存期、适用期和最终有效性能指标。     

竹材液化树脂发泡材料的性能测试及应用评价

对竹材液化树脂发泡材料及人造板覆面的复合发泡材料的性能进行测试.结果显示:树脂发泡材料的性能优良,表现密度为0.128 g/cm3,压缩强度为0.22 MPa,导热系数为0.032 W/(m·K),氧指数最小值为41.7.制成的水泥纤维板覆面复合发泡材料,隔声效果良好,隔声量为37 dB;竹帘板覆面复合发泡材料达到B1级难燃材料的要求,为市场提供一种全新的建筑墙体材料.     

竹材液化树脂发泡材料发泡工艺的研究

利用竹材液化产物树脂发泡,制备新型墙体材料。在已进行竹化液化和树脂化优化工艺试验的基础上,通过单因素试验,筛选出发泡剂为正戊烷;再通过正交试验,分析发泡剂、填料和固化剂等用量,对发泡材料表观密度和压缩强度的影响。在试验得出优化工艺的条件下,制得发泡材料的表观密度约0.14g/cm3,压缩强度达454.5kPa。     

三聚氰胺甲醛浸渍树脂的改性研究

为提高三聚氰胺甲醛（MF）浸渍树脂的储存稳定性和柔韧性,联合二甘醇和己内酰胺,对MF树脂进行改性。分析甲醛与三聚氰胺的量比,水、二甘醇和己内酰胺的加量等因素,对改性树脂性能的影响。结果表明,二甘醇和己内酰胺联合改性的方法,可同时提高MF树脂的储存稳定性和柔韧性;并提出最优化工艺参数。     

Characterization of wood-based molding bonded with citric acid

The wood-based moldings were fabricated by using only citric acid as an adhesive. The mechanical properties, water resistances, thermal properties and chemical structure were investigated. Wood powder obtained from Acacia mangium was mixed with citric acid under certain weight ratios (0–40 wt%), and each powder mixture was molded using two types of metal molds at 200°C and 4 MPa for 10 min. The modulus of rupture and the modulus of elasticity values of the wood-based molding containing 20 wt% citric acid were 35.8 MPa and 5.4 GPa, respectively. The maximum impact strength was 0.94 kJ/m² with the same citric acid content. The water resistance increased with increasing citric acid content, and the good resistance to boiling water was also recognized. However, some elution of substances derived from citric acid was observed at high levels of citric acid, causing a decrease in the thermal properties. The ester linkages were detected by Fourier transform infrared spectroscopy, indicating that the citric acid reacted with the wood. Our results demonstrated that citric acid brought about good adhesiveness for fabricating the wood-based molding.     

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℃.     

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.     

偶氮二甲酰胺发泡剂对脲醛树脂性能的影响

采用单因素试验方法,将偶氮二甲酰胺发泡剂与脲醛树脂复配制备发泡型胶黏剂,测试胶黏剂的基本性能及拉伸剪切强度,利用热重分析仪(TG)和同步热分析仪(TG-DSC)对胶黏剂的热稳定性和固化特性进行表征。结果表明:偶氮二甲酰胺发泡剂的加入有利于提升树脂体系的流动性,降低树脂的初期固化速度,提高树脂的热稳定性,且对树脂的固体含量及黏度无明显影响;较优的发泡剂添加量为6%;拉伸剪切强度为2.45 MPa。开发的偶氮二甲酰胺/脲醛树脂发泡胶黏剂在轻质人造板领域具有较大的应用潜力。     

竹材液化树脂发泡材料的性能与技术要求

根据生产性试验,对竹材液化树脂发泡材料及复合发泡材料的制备工艺进行修正和完善,并对其性能和技术要求进行探讨.分析结果表明:竹材液化树脂发泡材料及复合发泡材料的制备工艺成熟,可实现重复性生产；参考或借鉴相应的国家标准测试方法,可全面测试材料的性能；产品规格尺寸能够满足装配式建筑工程要求.     

热压工艺参数对三聚氰胺饰面刨花板甲醛释放量的影响

以市售刨花板和三聚氰胺浸渍纸为原料,制备三聚氰胺饰面刨花板.采用L9（34）正交试验考察热压温度、热压时间、热压压力3个热压工艺参数对三聚氰胺板甲醛释放量的影响.采用国家标准（GB/T 17657-1999）《人造板及饰面人造板理化性能试验方法》干燥器法检测甲醛的释放量.试验结果表明,热压温度对甲醛释放量影响最大、热压时间其次、热压压力影响最小,其中热压温度对甲醛释放量有显著影响,热压时间和热压压力的影响并不显著.热压工艺参数提高,会引起热压后的三聚氰胺板前期的甲醛释放量明显升高.确定饰面刨花板甲醛低释放的最优化生产工艺参数为热压温度170℃、热压时间40s、热压压力2.5 MPa.     

国外人造板甲醛散发研究现状

本文根据大量的国外文献资料综述了人造板中游离甲醛产生的原因、甲醛散发量的定量测试方法、影响甲醛向外界散发的诸种因素以及降低人造板甲醛散发量的各种措施。     

预处理对废旧人造板再生材料化学特性的影响

对粉碎后的废旧人造板原料进行冷水、热水、1％NaOH处理，通过测定预处理后材料的pH值、缓冲容量、胶固化时间，探讨预处理对废旧人造板材料化学特性的影响。试验结果表明：（1）相对于冷水和热水处理来说，1％NaOH处理使得3种木质材料的pH值极显著升高，最高可达10．41；（2）酸碱缓冲容量、UF胶固化时间在3种预处理方式间均有较显著差异，即随酸缓冲容量的增加UF胶固化时间缩短，而随碱缓冲容量的增加固化时间则延长。     

竹丝模压刨花板生产工艺初探

以竹丝为原料,以脲醛树脂和石蜡等为辅助材料,在一定的工艺参数下进行模压,然后对模压板材的物理力学性能进行检测和评价。结果表明,本研究设计的工艺方案可行,制成的竹丝模压制品性能可以达到在干燥状态下使用的家具及室内装修用刨花板要求。经分析发现,模压温度是最大的影响因素。     

生态木竹纤维复合装饰板材成型工艺

天然纤维复合材料是国内外近年蓬勃兴起的一类新型绿色复合材料。本文研发了一种用于家具及室内装饰的多层复合板,其利用竹、木等植物纤维、原生态树脂、重钙粉为原料,采用共挤复合一次成型工艺实现产品其表层（植物纤维同质透心柔性卷材）与芯层（植物纤维微发泡材料）一次复合成型。同时,结合开炼、捏合和无胶黏剂复合等多项成型工艺新技术。产品生产和使用过程绿色环保,具有广阎的发展前景。