木质素改性树脂制备刨花板的工艺探究

采用工业木质素酚醛树脂作为胶黏剂,通过设计正交试验,研究制备工艺对刨花板物理力学性能的影响。结果表明:热压时间对刨花板静曲强度和内结合强度影响最大;固化剂添加量对弹性模量的影响最大;木质素改性胶黏剂耐水性较差,其施加量对24h吸水厚度膨胀率的影响最大。本试验范围内,最佳制备工艺为:热压温度160℃、热压时间600s、施胶量9%,不用添加固化剂。     

马来酸酐偶联剂对麦秸／废旧聚丙烯复合材料性能的影响

以麦秸和废旧聚丙烯为原料,以马来酸酐作为偶联剂,异氰酸酯(MDI)作为胶黏剂,采用热压工艺压制麦秸/废旧聚丙烯复合材料,通过正交实验研究了偶联剂对该复合材料力学性能的影响。结果表明:单独施用马来酸酐偶联剂,内结合强度极低,静曲强度较低,吸水厚度膨胀率较高,板材性能差;与施用马来酸酐偶联剂相比较,单独施用MDI胶黏剂,内结合强度提高,吸水厚度膨胀率值降低,材料的综合性能好于施用马来酸酐偶联剂的情况,但还不能完全达到刨花板国家标准(GB/T4897.1-4897.7-2003)要求;同时施用马来酸酐偶联剂和MDI胶黏剂时,除密度对内结合强度影响较大外,聚丙烯含量对内结合强度、马来酸酐用量对内结合强度、施胶量对静曲强度和吸水厚度膨胀率均有显著影响,其中马来酸酐用量对内结合强度的影响最为显著。但过多的马来酸酐不但起不到促进作用,反而影响了胶黏剂的胶结性能。     

废胶膜纸用于刨花板制备研究

采用废浸渍胶膜纸作为胶黏剂替代部分脲醛树脂制备刨花板,探索了废胶膜纸添加量、添加位置以及废胶膜纸尺寸对刨花板理化性能(静曲强度、弹性模量、内结合强度、2 h吸水厚度膨胀率、甲醛释放量)的影响。结果表明,废胶膜纸可以作为胶黏剂替代部分脲醛树脂制备合格刨花板;添加到刨花板芯层的效果优于添加到刨花板表层;片状废胶膜纸的效果优于粉末状废胶膜纸。本研究使用15%的片状废胶膜纸(预固化度为50%)替代约3%的脲醛树脂加入到芯层刨花中,所制备的刨花板满足P2型干燥状态下家具用刨花板的要求,但加入废胶膜纸后刨花板的甲醛释放量会增加。     

木质素基豆粕胶黏剂胶合板热压工艺研究

以酶解木质素和豆粕为原料制备了木质素基豆粕胶黏剂,优化了木质素基豆粕胶黏剂应用于杨木胶合板的热压工艺参数,探讨了不同工艺参数对胶合板胶合强度的影响。试验结果表明,木质素基豆粕胶黏剂制备胶合板的优化热压工艺参数为热压温度120℃、热压时间7.5 min(75 s/mm)、热压压力0.9 MPa、单面施胶量180 g/m2;影响胶合板胶合强度的工艺参数主次顺序是热压温度、热压压力、施胶量、热压时间;采用优化热压工艺条件制备3层胶合板,其Ⅱ类胶合强度大于1.0 MPa,符合GB/T 9846—2015《普通胶合板》中Ⅱ类胶合板要求。     

定向刨花板饰面工艺初探

以定向刨花板(OSB)为研究对象,采用单因素试验方法,探讨OSB表面砂光程度、施胶量及饰面材料类型对饰面OSB物理力学性能的影响。结果表明:采用不同饰面工艺制得的饰面OSB,其静曲强度值40 MPa、弹性模量4 500 MPa、表面胶合强度0.50 MPa;饰面OSB的静曲强度、弹性模量及表面胶合强度随基材OSB表面砂光平整度的提高而增大,随施胶量的增加呈现先增加而后降低的规律,随饰面材料种类不同而不同;基材砂光处理和施胶量对饰面OSB的24 h吸水厚度膨胀率的影响不显著。     

一种栲胶刨花板的制备方法

采用栲胶和聚乙烯亚胺配置的胶黏剂与木材刨花按照一定比例搅拌均匀后热压成一种新型栲胶刨花板。制备的刨花板内结合强度、静曲强度、密度偏差和甲醛释放量完全符合国家标准要求,并具有加工工艺简单、灵活、方便,不受生产工序调整的影响等优点,可在拌胶后的较长时间内完成板材制备。     

脲醛胶杨木/麦秸复合刨花板的工艺研究

采用正交试验的方法,研究了施胶量、热压温度、热压时间、杨木/麦秸刨花质量比例等工艺因素对脲醛胶杨木/麦秸复合刨花板的静曲强度、弹性模量、内结合强度、吸水厚度膨胀率等性能的影响。结果表明:采用杨木和麦秸为原料制造脲醛胶杨木/麦秸复合刨花板是可行的,其优化工艺参数为施胶量14%、单位热压时间40s/mm、热压温度180℃,杨木/麦秸刨花质量比例7/3。     

脲醛胶杨木/麦秸复合刨花板的工艺研究

采用正交试验的方法,研究了施胶量、热压温度、热压时间、杨木/麦秸刨花质量比例等工艺因素对脲醛胶杨木/麦秸复合刨花板的静曲强度、弹性模量、内结合强度、吸水厚度膨胀率等性能的影响。结果表明：采用杨木和麦秸为原料制造脲醛胶杨木/麦秸复合刨花板是可行的,其优化工艺参数为施胶量14%、单位热压时间40s/mm、热压温度180℃,杨木/麦秸刨花质量比例7/3。     

改性山核桃外果皮/竹刨花板制造工艺研究

以漆酶改性处理的山核桃外果皮,代替部分胶黏剂添加到竹刨花中,研究山核桃外果皮粉用量、胶黏剂用量、漆酶用量、防水剂用量,板坯含水率、热压温度、热压压力、热压时间对山核桃外果皮/竹刨花板性能的影响;确定最优化的制板工艺参数:山核桃外果皮添加量10%、漆酶用量60 U/g、施胶量6%、防水剂用量1%,板坯含水率27%、热压温度200℃、热压压力3 MPa、热压时间为16 min。     

三聚氰胺改性脲醛树脂胶黏剂在E0级强化木地板基材中的使用特性分析

生产E0级强化木地板基材的三聚氰胺改性脲醛树脂胶黏剂对热压温度和热压时间非常敏感。当热压温度和热压时间在较小范围内波动时,使用此类胶黏剂制造的中/高密度纤维板内结合强度和24h吸水厚度膨胀率均变化较大。少量固化剂的添加也会影响强化木地板基材的两项指标。相同工艺制造的不同批次的胶黏剂其凝胶时间变化较大,不同的凝胶时间应对应不同的热压温度和热压时间。     

Physical and mechanical properties of gypsum particleboard reinforced with Portland cement

High thickness swelling, high water absorption and low mechanical properties of gypsum particleboard limit its utilization in building construction. Gypsum particleboard reinforced with Portland cement could result in a product with higher mechanical properties and an acceptable resistance to moisture. Physical and mechanical properties of gypsum-cement particleboards were analyzed for specimens previously conditioned at 20?°C and 60% relative humidity and then soaked in water for 24 hours. The results showed that Portland cement incorporation increased the mechanical resistance of the boards. In the dry state, Portland cement addition generated a modulus of rupture increase ratio of 53% and an internal bond strength increase ratio of 206%. Higher increase ratios were obtained after 24 hours water soaking. An increase ratio of 642% was obtained for the modulus of rupture and 97% for hardness. Furthermore, the addition of Portland cement resulted in a reduction ratio of 21% for water absorption after 2 hours water soaking and 26% after 24 hours water soaking. Moreover, reduction ratios of 43% and 61% in thickness swelling and 33% and 46% in linear variation were observed after 2 and 24 hours water soaking. It can be concluded that Portland cement is a suitable reinforcing material for improving the performance of gypsum particleboard.     

The manufacture of particleboards using mixture of reed (surface?layer) and commercial species (middle layer)

This research was conducted to investigate the suitability of reed (Arundo donax) as a substitute for wood in laboratory made 3-layer particleboard in order to supplement the supply of raw material for the Iranian particleboard industries. The ratio of the mixture of reed and wood particles were 20:80, 30:70, and 40:60, respectively, in the surface and middle layers. Press temperatures were chosen at two levels of 165 and 185?°C. Three levels of urea formaldehyde resin were selected for the surface layers, namely: 8, 10, and 12 percent. The experimental panels were tested for their mechanical strength including modulus of elasticity (MOE), modulus of rupture (MOR), internal bonding (IB) and physical properties (thickness swelling and water absorption) according to the procedure in DIN 68763. In general, the results show that reed has a positive effect on the mechanical and physical properties of boards. In this research, the treatment with 40% reed, 12% resin in the surface layers and a 185?°C press temperature has resulted in an optimum reed board product.     

Particleboards production from date palm biomass

Date palm biomass is a renewable natural resource that has not widely been utilized in industry. The objective of this study was to examine some chemical properties of date palm trunk and rachis (holocellulose, cellulose, lignin and extractives) and to evaluate their suitability to produce composite panels. Particleboards were produced using trunk and rachis as an alternative raw material for forest products industry in the presence of two types of polycondensation resins (phenol–formaldehyde and melamine urea–formaldehyde) which were selected as binding agents. The panels were tested for their physical (water absorption and thickness swelling) and mechanical (modulus of rupture, modulus of elasticity and internal bond strength) properties. The internal bond strength of date palm trunk and date palm rachis based boards met the requirements of the general purpose product standards (EN 312) at 0.70 g/cm³ density. The panels made with phenol–formaldehyde resin showed better performance with respect to the panels made with melamine urea–formaldehyde. In addition, the particleboard made with date palm trunk particles had better quality compared to the particleboard made from date palm rachis particles. Based on preliminary results of this work, raw materials from date palm trunks and rachis can have a promising potential in the manufacture of particleboards and as a substitute for wood in board production.     

Influence of processing parameters on some properties of oil palm trunk binderless particleboard

The objective of the study was to evaluate some properties of experimental binderless particleboards produced from various processing parameters. Three different temperatures (160, 180, 200 °C), two different hot pressing times (15, 20 min) and two different pressures (5, 10 MPa) were applied in manufacturing the binderless particleboard. Three replications of each of the 12 different types of boards with a target density of 0.60 g cm^?3 were produced. The thickness swelling, dimensional changes associated with changes in relative humidity, bending strength, internal bonding strength, and soil burial decay test were evaluated. Increase of temperature, duration of hot pressing and pressure increased the properties of specimens. Thickness swelling nearly met the requirement of European Standard for use in humid condition. Some of the specimens showed promising mechanical properties and met the requirement of European Standard.     

芦苇／木材复合包装材料制造工艺的研究

研究利用芦苇为原料制造单层刨花板的可行性。分别制备了纯杨木、纯芦苇、杨木/芦苇刨花板,按照国家标准的要求,对板材的物理性能（吸水厚度膨胀率）和力学性能（静曲强度、弹性模量、内结合强度）进行了测试。测试了芦苇添加量及热压时间对芦苇/木材复合材料性能的影响。试验结果表明,纯芦苇制造的刨花板的质量最差。杨木/芦苇刨花板的性能随着混合原料中芦苇含量的上升而下降,而适当延长热压时间可提高板材的物理力学性能。芦苇添加量不高于50％时,杨木/芦苇刨花板的力学性能达到国家标准的要求。     

Versuche zur Verringerung der Dickenquellung von Spanplatten bei der Wasserlagerung und in feuchter Luft

Investigations on the sorptional behaviour, thickness swelling, and mechanical properties of particleboards prepared from UF-resinated wood particles treated with 1% and 2% paraformaldehyde prior to pressing led to the following conclusions: Addition of paraformaldehyde decreased the hygroscopicity of particleboard only insignificantly. However, it led to a pronounced reduction in the thickness swelling of particleboards in water as well as in humid air. The reduction in thickness swelling due to treatment with paraformaldehyde was higher for particleboards prepared without paraffin as a sizing agent than for particleboards containing this additive. Moreover, the treatment with paraformaldehyde increased the transverse tensile strength of the particleboards to a high extent (35% to 50%).     

Steps to make the natural adhesive of Acacia mimosa tannin resistant to boiling water using Tinnevelly senna for particleboard production

Adding a small amount of Tinnevelly senna seed flour to the natural adhesive of condensed tannin from acacia mimosa type decreases the thickness swelling and water absorption in particleboards significantly. Likewise, internal bond, modulus of rupture and modulus of elasticity increase. FTIR did not show any change in the adhesive structure. DSC and TGA showed a link between the additive of Tinnevelly senna and natural adhesive of acacia mimosa tannin, which obviously brings about the resistance to boiling water in particleboard manufacturing when using this adhesive mix.     

Improving the physical and mechanical properties of particleboards made from urea–glyoxal resin by addition of pMDI

The effect of pMDI on physical and mechanical properties of the particleboards made from urea–glyoxal resin was investigated. The nontoxic and ecofriendly urea–glyoxal (UG) resin was synthesized under weak acid conditions, and its different properties were measured. Then, pMDI at various contents (4, 6 and 8% on resin solids) was added to the UG resin prepared. The thermal and physicochemical properties of the resins prepared as well as their water absorption, flexural properties (flexural modulus and strength) and internal bond (IB) strength of the particleboard panels bonded with them were measured according to standard methods. According to the physicochemical results obtained, the addition of pMDI significantly accelerated the gel time and increased the viscosity and solids content of UG resins. Differential scanning calorimetry indicated that the addition of pMDI decreases the onset and curing temperatures of the UG resin. Physical analysis results of the panels indicated that the particleboards made from UG resins with isocyanate yielded lower water absorption when compared to those bonded with the control UG resins. Based on the findings of this research work, the mechanical properties of particleboard panels bonded with UG resins could be significantly enhanced by the addition of increasing percentages of pMDI. The panels having 8 wt% pMDI exhibited the highest flexural modulus, flexural strength and IB strength value and the lowest water absorption among all the panels prepared.