Properties of Bark Particleboard Bonded with Demethylated Lignin Adhesives Derived from Leucaena leucocephala Bark

Lignin extraction from bark can maximize the utilization of biomass waste,offer cost-effectiveness,and promote environmental friendliness when employed as an adhesive material in bark particleboard production.Particles of fine(0.2 to 1.0 mm),medium(1.0 to 2.5 mm),and coarse(2.5 to 12.0 mm)sizes,derived from the bark of Leucaena leucocephala,were hot-pressed using a heating plate at 175℃for 7 min to create single-layer particleboards measuring 320 mm×320 mm×10 mm,targeting a density of 700 kg/m^(3).Subsequently,the samples were trimmed and conditioned at 20℃and 65%relative humidity.In this study,we compared bark particleboard bonded with urea formaldehyde(UF)adhesive to fine-sized particleboard bonded with demethylated lignin adhesive.The results indicated that bark particleboards utilizing demethylated lignin and UF adhesives exhibited similar qualities.Coarse particleboard showed differences in modulus of elasticity(MOE)and modulus of rupture(MOR),while medium-sized particles exhibited significant variations in moisture content(MC)and water absorption(WA).Furthermore,the thickness swelling of coarse and medium-sized particles under wet and oven-dried conditions exhibited notable distinctions.Overall,the demethylated lignin adhesive extracted from L.leucocephala bark demonstrated similar quality to UF adhesive,with particle size correlating inversely to the strength of the bark particleboard.

Effect of Multi-Hydroxyl Polymer-Treated MUF Resin on the Mechanical Properties of Particleboard Manufactured with Reed Straw

The poor bonding performance between aqueous adhesives represented by melamine-urea formaldehyde(MUF)resins and reed straw hinders their applications in the field of non-wood-based panels.Multi-hydroxyl polymers are highly reactive and are often used as crosslinkers.This study fabricated a resin with a strengthened crosslinked structure by combining a multi-hydroxyl polymer and MUF resin prepolymer.The reed particleboard was prepared by using this resin as an adhesive and reed stalk as the matrix.The results show that neighboring molecules combined to form C–O–C bonds that strengthened the cross-linked structure of the resin.In addition,the viscosity of the resin was increased,and a continuous adhesive layer on the surface of reed particles was formed,which slowed the penetration of reed particles.The adhesive layer significantly improved the mechanical properties of the reed particleboard.The maximum modulus of rupture(MOR),modulus of elasticity(MOE),and internal bonding strength(IB)of the reed particleboard were 33.53,4126,and 0.79 MPa,respectively.The IB of the board was 3.3 times higher than that of the reed particleboard prepared with a conventional MUF resin.Reed straw is a non-wood biomass material that has the advantage of sustainable development and may replace woodbased materials to produce particleboard.This resin-prepared reed particleboard is expected to be used in areas such as custom furniture and engineering materials.

Self-Cross-Linked Tannin-Aminated Tannin Surface Coatings for Particleboard

Aminated tannins were prepared by reacting mimosa condensed tannin extract with ammonia yielding the substitution of many,if not all of the tannin hydroxyl groups with–NH_(2)groups.A tannin-aminated tannin(ATT)particleboard coating was then prepared by reacting raw tannin extract with aminated tannin extract and thus cross-linking the two by substituting tannin’s hydroxyl groups with the–NH_(2)groups on the aminated tannin to form–NH-bridges between the two.The resulting particleboard coating gave encouraging results when pressed at 180℃for 3 min.Conversely,the system in which tannin was reacted/cross-liked with urea(ATU)by a similar amination reaction did not perform as well as the ATT system,and this even when a higher curing temperature and longer hot press time were used.In particular its water repellence was worse probably due to the presence of urea and such a system with lower reactivity.Nonetheless,substituting the tannin–OHs with the urea–NH_(2)groups appeared to also take place.ATT gave better results than ATU as regards water repellence and mechanical resistance as shown by the cross cut test.The ATT system was shown to be between 95%and 98%biosourced.The difference appeared to be due,by TMA analysis,to the much faster formation of the ATT hardened network leading to a better cross-linked polymer coating.The chemical species formed for both the ATT and ATU system were studied by MALDI ToF and CP MAS^(13)C NMR.

玉米秸秆刨花板压制工艺优化及吸水厚度膨胀率

农作物秸秆用作人造板原材料,可减少环境污染,缓解木材供需紧张,秸秆中纤维素与木质素含量可以满足人造板生产要求。以玉米秸秆刨花为原料,在一定热压压力、热压时间、刨花密度、热压温度下,采用不同施胶量无机胶黏剂压制玉米秸秆刨花板,探索最优工艺参数及玉米秸秆刨花板吸水厚度膨胀率变化规律。结果显示:压制玉米秸秆刨花板的最优工艺参数为刨花含水率12%、热压压力1.6MPa、热压时间9min、刨花密度1.0g/cm^(3)、施胶量20%、热压温度90℃;影响玉米秸秆刨花板吸水厚度膨胀率的因素依次为刨花含水率>热压压力>热压时间>刨花密度>施胶量>热压温度。试验结果表明:在吸水厚度膨胀率合格的前提下,玉米秸秆刨花板的内结合强度、弹性模量、静曲强度均符合国家标准规定的性能要求。

中国刨花板产业创新发展近况及展望

从产业发展和创新两个方面阐述了“十三五”以来中国刨花板产业快速发展的原因和特点,展望了中国刨花板产业未来的发展趋势,提出了中国刨花板产业未来发展应该关注的重点。

印刷装饰纸透气度对浸渍胶膜纸饰面刨花板表面耐开裂性能的影响

对比研究了不同透气度印刷装饰纸,经相同浸渍、压贴工艺制成饰面刨花板的表面耐龟裂性能和表面耐冷热循环性能。结果表明,印刷装饰纸透气度(单位s/100 mL)数值越低,透气性能越好,相同工艺条件制备浸渍胶膜纸时上胶越容易,透气度为16.37 s/100 mL的样品比透气度为65.02 s/100 mL的浸胶量提高了8.4%。当印刷装饰纸透气度大于35 s/100 mL时,由其浸胶后饰面制得的饰面刨花板表面耐龟裂性能和耐冷热循环性能不合格率分别为87.5%和75.0%。

葡萄藤化学组分及藤/木复合刨花板性能研究

在我国,每年可以产生多达600万t的葡萄藤,它们大多被废弃在田地间,造成了巨大浪费。利用废弃的葡萄藤作为木质刨花板原料的部分替代材料可变废为宝,因此,研究了葡萄藤碎料添加量、施胶量以及等离子体预处理技术对复合刨花板性能的影响。结果表明,由于葡萄藤碎料自身性能较差且无法与木刨花很好地结合,葡萄藤碎料的加入会使得复合刨花板性能下降,在葡萄藤碎料添加量达到25%时葡萄藤/木复合刨花板的静曲强度、弹性模量、内结合强度分别下降了35.9%,35.0%,13.1%,吸水厚度膨胀率增幅为31.2%。施胶量的增大可以改善葡萄藤碎料加入带来的板材性能下降问题。葡萄藤碎料经等离子体预处理改性之后的润湿性能提高,对胶液的吸收能力增强,压制出的葡萄藤/木复合刨花板相比未改性的葡萄藤/木复合刨花板,在施胶量为10%的情况下,其静曲强度、弹性模量、内结合强度分别提升了23.0%,21.6%,10.7%;在施胶量为14%的情况下,分别提升了17.4%,11.8%,7.4%。等离子体处理后葡萄藤碎料与木刨花之间的结合也更加紧密,吸水厚度膨胀率也分别由9.32%和6.85%降至8.68%和5.86%。

不同摩尔比脲醛树脂的制备及其在刨花板中的运用

为了探究不同F/U摩尔比在同一制备工艺下对脲醛树脂的影响,采用0.9、1.0、1.05、1.1不同摩尔比分别制备脲醛树脂,以此分析脲醛树脂的理化性能,同时为了更好地探索脲醛树脂的应用性,制备刨花板并分析刨花板力学性能。结果表明:1.05摩尔比条件下综合性能最佳。在最佳工艺下制备脲醛树脂游离甲醛质量分数为0.21%,刨花板板材MOR与MOE为14.07MPa和1933MPa,IB为0.48MPa,甲醛释放量为2.1mg(100g)^(-1),所制备刨花板都满足国家标准P2型,该研究为脲醛树脂的制备工艺以及刨花板实际应用生产提供了科学依据.

油茶果壳生物基材料研究进展及展望

油茶作为木本食用油料树种在南方各省被广泛种植,其加工剩余物油茶果壳若未合理有效利用,将对空气、水体等生态造成污染。油茶果壳富含中孔结构,用其制备活性炭,可用于吸附或电池、电极与电容器领域;油茶果壳去除木质素得到的综纤维素,可制备综纤维素膜材料或纳米纤维素膜材料,用于包装、纺织和医疗等领域;油茶果壳富含木质素及茶皂素等天然活性物质,可制备油茶果壳基树脂用作做胶合材料并具有耐恶劣气候及阻燃等特性;油茶果壳经热压工艺制备刨花板,可用于家具及建筑等领域;油茶果壳作为增强相与塑料复合制备木塑复合材料,可用于园林和室内装潢等领域。本文综述了油茶果壳在上述领域的研究进展,并对油茶果壳生物基材料提出了展望。

基于电子鼻技术评定刨花板气味等级方法初探

以刨花板为研究对象,通过PEN3电子鼻对不同气味等级的刨花板样品进行气味检测和数据分析。结果表明,PEN3电子鼻结合主成分分析法(PCA)可对刨花板气味等级进行区分,但对LY/T 3236—2020《人造板及其制品气味分级及其评价方法》中的“气味明显,但气味不令人难受”“明显让人感觉难受的气味”这2个等级未能准确区分。建议扩充各气味等级刨花板样本量,并以此建立样品LY/T 3236—2020气味等级检测结果与电子鼻数据间的模型,完善刨花板气味等级电子鼻检测数据库,实现新样品气味的电子鼻快速检测。

刨花板含水率对板材质量的影响

刨花板含水率,如果不能与生产或使用地域空气湿度形成平衡,就会造成刨花板翘曲变形或者开料后出现香蕉弯(月亮弯);如果暂时没有出现变形,经过二次加工并做成家具,也会导致家具部件扭曲、缩胀,或者家具部件表面装饰纸产生龟裂,尤其是采用异氰酸酯(pMDI)胶黏剂生产的无醛添加刨花板更容易出现类似的情况,所以必须从根本上解决刨花板含水率问题,才能避免给刨花板后续加工、使用造成不必要的麻烦。

机器视觉在刨花板表面缺陷检测中的应用现状与建议

介绍了国内刨花板表面缺陷机器视觉检测技术的研究现状,并指出了当前该技术存在的缺陷,如识别准确率偏低、易受环境干扰等问题。针对这些问题,本文提出了相应的机器视觉缺陷检测技术改进建议,旨在为刨花板表面缺陷的快速、精准检测提供有价值的参考。

提高刨花板内胶合强度5%分位值的措施

介绍刨花板国家标准关于内胶合强度5%分位值的计算方法,并分析了影响内胶合强度5%分位值的主要因素,提出提高内胶合强度5%分位值措施,以期为刨花板企业生产提供参考。

低醛阻燃防潮家具用刨花板生产工艺探讨

介绍了一种家具用低醛阻燃防潮刨花板生产工艺。生产过程中,芯层采用低物质的量比三聚氰胺改性阻燃脲醛树脂,辅以少量聚异氰酸酯(pMDI)以促进固化;表层则使用低物质的量比三聚氰胺改性脲醛树脂,并添加少量阻燃剂。所制得的刨花板物理力学性能符合GB/T 4897—2015《刨花板》标准中潮湿状态下使用的家具型(P6型)刨花板的要求,甲醛释放量满足日本JIS A5908:2022《刨花板》中F☆☆☆☆标准,阻燃性能达到美国ASTM E84《建筑材料表面燃烧特性测定方法》A类标准。

竹木复合低密度细表面定向刨花板的研制

探讨了以毛竹、杉木为原料,以异氰酸酯为胶黏剂并添加增黏剂等多种助剂,制备竹木复合低密度细表面定向刨花板的生产工艺。研究结果表明,在适当增加施胶量的前提下,以毛竹和杉木混合生产竹木复合低密度细表面定向刨花板是可行的,刨花板的密度最低可以做到600 kg/m^(3),且本试验中所制备的竹木复合细表面定向刨花板的物理力学性能随密度加大而提高,优化热压温度、热压压力以及热压时间可明显改善其性能。

Cement-bonded particleboard with a mixture of wheat straw and poplar wood

We investigated the hydration behavior and some physical/mechanical properties of cement-bonded particleboard （CBPB） containing particles of wheat straw and poplar wood at various usage ratios and bonded with Portland cement mixed with different levels of inorganic additives. We determined the setting time and compression strength of cement pastes containing different additives and particles, and studied the effects of these additives and particles on thickness swelling, internal bond strength and modulus of rupture of CBPB by using RSM （Response Surface Methodology）. The mathematical model equations （second-order response functions） were derived to optimize properties of CBPB by computer simulation programming. Predicted values were in agreement with experimental values （R2 values of 0.93, 0.96 and 0.96 for TS, IB and MOR, respectively）. RSM can be efficiently applied to model panel properties. The variables can affect the properties of panels. The cement composites with bending strength 〉 12.5 MPa and internal bond strength 〉 0.28 MPa can be made by using wheat straw as a reinforcing material. Straw particle usage up to 11.5% in the mixture satisfies the minimum requirements of International Standard, EN 312 （2003） for IB and MOR. The dose of 4.95% calcium chloride, by weight of cement, can improve mechanical properties of the panels at the minimum requirement of EN 312. By increasing straw content from 0 to 30%, TS was reduced by increasing straw particle usage up to 1.5% and with 5.54% calcium chloride in the mixture, TS satisfied the EN 312 standard.

Biological performance of particleboard incorporated with boron minerals

We compared resistance to decay, mold fungi, termites and insect larvae of particleboards incorporated with the raw boron minerals ulexite and colemanite to that of particleboards impregnated with the commercial boron preservative zinc borate, or boric acid plus a borax mixture. We also quantified water absorption, thickness swell and boron release of particleboards. Ulexite had the best decay resistance, and colemanite had the best termite resistance. However, ulexite and colemanite were not as effective as zinc borate or the boric acid/borax mixture in preventing mold growth. In general, the boric acid/borax mixture combination was more effective against Anobium larvae than the other treatments. Less boron was released by specimens containing zinc borate and colemanite than by those containing ulexite or the boric acid/borax mixture. In general, water absorption and thickness swell were similar among the different treatments, but both were slightly higher in the ulexite-incorporated specimens. Further mechanical tests will be needed to evaluate the particle- board properties and thereby the compatibility of these boron minerals with various manufacturing processes.

Preparation and properties of waste tea leaves particleboard

Urea-formaldehyde （UF） adhesive is the main source of formaldehyde emission from UF-bonded boards. The components in waste tea leaves can react with formaldehyde to serve as a raw material in the production of low formaldehyde emission boards. In our study, waste tea leaves and UF adhesive were employed in the preparation of waste tea leaves particleboard （WTLB）. An orthogonal experimental method was applied to investigate the effects of process parameters on formaldehyde emission and mechanical properties of WTLB. The results indicated that： 1） waste tea leaves had the ability to abate formaldehyde emission from boards; and 2） density of the WTLB was a significant factor affecting its modulus of rupture （MOR）, modulus of elasticity （MOE） and internal bonding （IB）.

Use of amino silane coupling agent to improve physical and mechanical properties of UF-bonded wheat straw(Triticum aestivum L.) poplar wood particleboard

We evaluated the potential use of amino silane coupling agent （SiNH） to improve physical and mechanical properties of UF-bonded wheat straw （Triticurn aestivum L.） poplar wood particleboard. We examined the effects of varied content of silane coupling agent content and ratios of straw to poplar wood particles on particleboard prop- erties. The ratios of straw to poplar wood particles were 100：0, 85：15, 70：30 and 55：45. Silane coupling agent content was tested at three levels, 0, 5 and 10 %. The experimental panels were tested for their mechanical strength, including modulus of elasticity （MOE）, modulus of rupture （MOR）, intemal bonding （IB） and physical properties according to procedures specified in DIN 68763 （Chipboard for special purposes in building construction： concepts, requirements, testing, 1982-03, 1982）. All board properties were improved by the addition of silane cou- pling agent. The use of poplar wood particles had a positive effect on the mechanical properties of wheat straw parti- cleboard but had a negative effect on physical properties （thickness swelling and water absorption）.

Observation and Analysis of Gypsum Particleboard using SEM

The microstructures of gypsum board and gypsum particleboard were observed by SEM. The effects of retarder and waterproof agent on the shape and the average dimension of the gypsum crystal were discussed. The mechanism was investigated as well. Four typical instances, i e, the gypsum crystal shape, the gypsum combined with particles on the particles surface, the gypsum combined with particles on the wood cross section and the gypsum combined with particles inside the wood cell cavity were selected and observed. Furthermore, the agglomeration and cementation mechanism between gypsum and particle were studied.