MUF胶黏剂的稀释对降低纤维板施胶量的影响

研究了三聚氰胺改性脲醛树脂(MUF)胶黏剂稀释前后低施胶量纤维板的物理力学性能,结果表明:随着施胶量的降低,纤维板的弹性模量(MOE)、静曲强度(MOR)和内结合强度(IB)有所降低,而吸水厚度膨胀率(TS)则有所上升。加水稀释至1.5倍的MUF胶黏剂可以明显提高施胶量为9%的纤维板的MOE、MOR和IB,降低纤维板的TS,而对甲醛释放量影响不大(E1级),并与12%施胶量的纤维板性能相当。而进一步稀释的MUF胶黏剂将使纤维板出现分层鼓泡等现象。     

工艺参数对无机胶黏剂稻草板性能的影响

以自主研发的无机胶黏剂和稻草碎料为原料,利用冷压成型工艺制备稻草板。通过单因素试验研究了胶黏剂与秸秆比例、稻草形态、板材结构和密度对稻草板物理力学性能的影响规律。试验结果表明,胶黏剂与细料、粗料、粗细混合料的质量比分别为2.2,2.0和2.0时,稻草板的性能最佳,均满足国家标准要求。在同等施胶量的情况下,粗料制备稻草板的静曲强度(MOR)和弹性模量(MOE)最大,混合料制备稻草板的内结合强度(IB)最大,吸水厚度膨胀率(TS)最小。同等细粗料比例下,单层结构稻草板的MOR、MOE、IB和TS均比3层结构稻草板大。稻草板的MOR、MOE、IB和TS与密度均呈密切线性相关,并得回归方程分别为y=19.148x-2.941 1,y=3 711.495x-343.151 2,y=1.902x-1.052 1和y=-2.336x+4.706 0。当密度大于1.0 g/cm3,稻草板的各项物理力学性能均符合GB/T 21723—2008的要求。另外,无机胶黏剂实现了稻草板的高效阻燃和抑烟特性。     

施胶量对无机杨木碎料板力学性能的影响

研究了施胶量对无机杨木碎料板物理力学性能的影响,并通过扫描电镜、红外光谱仪、X射线衍射仪、热重分析仪等分析了施胶量对无机杨木碎料板性能影响机制。结果表明:随着施胶量的增大,板材静曲强度(MOR)、弹性模量(MOE)均先增大后减小,施胶量为57%时板材MOR和MOE分别达到最大值21.5MPa、4 360MPa。而内结合强度(IB)随着施胶量的增大而逐渐增大,24h吸水厚度膨胀率(TS)随着施胶量的增加而减小。     

预埋PVC管空心刨花板平压成型技术

针对现有空心刨花板纵向强度低,对刨花要求高和需脱膜等缺陷,以不同板材厚度、空心孔距和芯层比例(芯层刨花质量比)作为影响因素,采用预埋PVC管平压成型的方式制造空心刨花板,对板材主要物理力学性能进行测试和分析。研究表明:采用预埋PVC管进行平压式空心刨花板制造是可行的,对板材性能有较大的增强作用。相同密度下厚度为16 mm的板材力学性能最好,芯层所占比例为2/3时,PVC管孔截面变形最小,空心孔距对板材力学性能影响不显著。板材的24 h吸水膨胀率(TS)随着厚度的增大呈下降趋势,力学性能随着厚度的增大而先下降后上升。当厚度为16 mm时,板材静曲强度(MOR)达到12.66 MPa,弹性模量(MOE)达到1.444 GPa,而24 h TS达到11.80%。板材的MOR和MOE随空心孔距的增大呈先下降后上升的变化趋势,对24h TS无明显影响,当空心孔距为20 mm时,板材的MOR达到12.47 MPa、MOE达到1.336 GPa、而24 h TS达到11.62%。板材的MOR和MOE随芯层比例的增大呈先下降后上升的变化趋势,对24 h TS无明显影响,当芯层比例为2/3时,板材的MOR达到12.04 MPa,MOE达到1.302 GPa,而24 h TS达到了10.68%。     

木质素和聚糖的酶催化交联产物在纤维板中的应用

利用木质素前驱物协同果胶在漆酶体系作用下处理麦草纤维,以湿法工艺制造高强度中密度纤维板.实验结果表明:经处理后,纤维板的24 h吸水厚度膨胀率(TS),纤维板的内结合强度(IB),静曲强度(MOR),弹性模量(MOE)分别达到16.7％,0 6MPa,25.1MPa,2 500 MPa.各项物理性能指标均达到或超过国家...     

浸胶工艺对绿竹重组竹材性能的影响

讨论胶黏荆固体含量、浸胶方式、浸胶时间等因素,对重组竹材物理力学性能的影响.结果表明:在本试验范围内,随着胶黏剂固体含量的降低,重组竹材的物理力学性能降低;随着浸胶压力的增大.重组竹材的静曲强度(MOR)和内结合强度(IB)均呈先增后减的趋势,弹性模量(MOE)基本不变;随着浸胶时间的延长,重组竹材的MOR和MOE无显著变化,IB提高.     

中密度纤维板/橡胶阻尼层状夹心复合材料的力学与隔声性能

将中密度纤维板与橡胶材料层合制备成层状夹心复合材料,并优化其制备工艺。结果表明:涂胶量对复合材料的弹性模量(MOE)、弯曲强度(MOR)、内结合强度(IB)具有极显著影响,热压压力对MOE、MOR影响极显著、对IB影响较小;热压时间对MOE、MOR的影响显著。随着涂胶量增加,复合材料的隔声性能提高;热压压力过大将导致橡胶厚度变薄,隔声性能降低。优化工艺条件下得到的层状夹心复合材料的隔声性能优于同等厚度MDF。     

聚乙烯醇/三聚氰胺改性脲醛树脂胶黏剂制备芦苇刨花板及性能研究北大核心

为解决普通脲醛(UF)树脂对芦苇材料胶合性能差的问题,以聚乙烯醇/三聚氰胺改性脲醛(PVA/MUF)树脂为胶黏剂制备芦苇刨花板。通过正交试验,研究密度、热压温度、热压时间、施胶量等因素对板材内结合强度(IB)、静曲强度(MOR)以及2 h吸水厚度膨胀率(TS)的影响。结果表明:芦苇刨花板的优化制备工艺为:密度0.85 g/cm3、热压温度160℃、热压时间5 min、施胶量12%。所制得的芦苇刨花板IB和MOR分别为1.00 MPa和21.4 MPa,与木材刨花板相当。未来,使用PVA/MUF树脂改性胶黏剂制备的芦苇刨花板有望替代传统木材刨花板。     

耐盐竹柳中密度纤维板的研究

以耐盐竹柳为原料,对其进行纤维形态分析,并分别将剥皮竹柳纤维和不剥皮竹柳纤维试制中密度纤维板,探讨胶粘剂施加量和板材密度对纤维板弹性模量(MOE)、静曲强度(MOR)、内结合强度(IB)和吸水厚度膨胀率(TS)的影响。结果表明:密度和施胶量均对其性能指标具有显著的影响,板材性能随着密度和施胶量的增加而提高;剥皮的竹柳纤维制得的纤维板性能优于未剥皮纤维制得的板材;剥皮竹柳纤维制造的纤维板在板密度为0.75 g/cm3、施胶量为12%时,其物理力学性能指标MOE、MOR、IB、TS都达到了国家标准GB/T11718-2009的要求;而未剥皮纤维制得的纤维板在施胶量为14%、板密度为0.75 g/cm3时,其性能指标达到国家相关标准的要求;树皮对纤维板的物理力学性能有明显的影响。     

原竹增强空心刨花板材性分析及其轴向抗压稳定性设计

以小径级原竹为增强材料,改善空心刨花板(EP)主要物理力学性能。同时,通过LVL和胶合板,对原竹增强刨花板进行覆面改性,为新材料的开发利用提供参考。通过对复合材料物理、力学指标进行测试,评定材料性能。并基于欧拉公式,对其作为轴向抗压材料进行稳定性设计。结果表明:原竹结构对EP材性有显著性影响,力学性能和尺寸稳定性均显著提高。其中,竹青对复合材料的内结合强度(IB)具有一定影响;原竹和覆面材料的加入可综合改善EP尺寸稳定性。不同覆面材料对吸水厚度膨胀率(TS)影响不显著,但对长度方向尺寸变化(LDC)影响显著;LVL改性材(LBRP)抗弯性能优于胶合板改性材(PBRP)。其中LBRP材料静曲强度(MOR)达到37.84 MPa,弹性模量(MOE)达14 577 MPa;不同覆面材料对MOR和MOE均有显著影响,但对MOE影响更为显著。此外,通过理论设计和计算,得到了轴向抗压材料的安全设计参考值范围。     

UF/PDMI组合胶黏剂在刨花板生产中的应用

采用脲醛树脂(UF)/聚合异氰酸酯(PDMI)组合胶黏剂,以不同的组合配比在较低热压温度(160℃)条件下用高含水率(9.0%)杂木刨花制备刨花板,检测其静曲强度、内结合强度以及2h和24h吸水厚度膨胀率。结果表明:聚合异氰酸酯(PDMI)的引入,可以显著提高刨花板的物理力学性能和耐水性能;将刨花终含水率提高至9.0%可节约刨花干燥能耗达13.0%以上;与脲醛树脂胶黏剂(UF)相比,使用PDMI/UF配比为1∶9的(10.0wt%PDMI)组合胶黏剂可以提高刨花板静曲强度80%,提高内结合强度150%;在不添加防水剂的条件下,可以将板材的2h吸水厚度膨胀率由31.0%提高至21.0%。该研究可为刨花板节能环保生产提供新思路。     

广宁县竹香骨下脚料制备竹碎料刨花板及其复合改性研究

采用竹香骨下脚料为原料,以脲醛树脂和三聚氰胺改性脲醛树脂胶粘剂制备竹碎料刨花板,并与木纤维复合改性,检测并分析了内结合强度、静曲强度、弹性模量和吸水性。结果表明,在热压温度为160℃时,竹碎料板和竹木复合碎料板的物理力学性能均满足国标规定在干燥状态下使用的普通用板要求。当木纤维与竹碎料复合后,复合板材的静曲强度和弹性模量有一定程度提高,但内结合强度降低。     

稻壳形态对稻壳--木材复合材料性能的影响

测试了稻壳形态对稻壳-木材复合材料物理力学性能的影响。试验结果表明，以20网日、30网日和40网目的稻壳为补充材料制备的密度为0．80g／cm^3的板的物理力学性能均达到国标二级品的要求。确立20网目的稻壳适宜于稻壳-木材复合材料。     

Manufacture of Light-weight Composite Panel from Kenaf

Light-weight composite panels were manufactured using kenaf core particles as core material and kenaf bast fiber-woven sheets as top and bottom surfaces. Methylene diphenyldiisocyanate （MDI） resin was used as the adhesive with the resin content of 4% for core particles and 50 g/m^2 for bast fiberwoven sheets. The target board densities were set at 0.35.0.45 and 0.55 g/cm^3. The composite panels were evaluated With Japanese Industrial Standard for Particleboards （JIS A 5908- 2003）.The results show that the composite panel has high modulus of rupture and internal bonding strength. The properties of 0.45 g/cm^3 density composite panel are： MOR 20.4 MPa. MOE 1.94 MPa, IB 0.36 MPa, WA142%, TS 21%. Kenaf is a good raw material for making light-weight composite panels.     

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).     

Formation of the density profile and its effects on the properties of particleboard

Summary Two types of particleboards bonded with an isocyanate resin, one with uniform vertical density profile (homo-profile), and the other with conventional U-shaped profile, were fabricated to various density levels using lauan (Shorea spp.) particles. The fundamental relationships between the density profile and the board properties were determined, and the results are summarized as follows: 1. In homo-profile boards, the moduli of rupture (MOR) and elasticity (MOE), internal bond (IB) strength, and screw withdrawal resistance (SWR), are highly correlated to the board mean density. 2. The bottom limit of the board density is estimated to be ca. 0.25 g/cm³, based on the correlation regressions between mechanical properties and mean density. 3. At equal mean density level, the MOR and MOE of the conventional particleboards are higher than the homo-profile boards, due to the higher density near the faces. However, the reverse is true for IB, owing to the presence of the low density core in the former. 4. The net impact of peak density on MOR and MOE is greater at higher mean density level while raising the core density results in more pronounced improvement in IB at lower density. 5. In addition to the compaction ratio, the dimensional stability of the board is also affected by the peak area and mat moisture content. Received 9 January 1997     

Investigation of a new natural adhesive composed of citric acid and sucrose for particleboard

The development of a natural adhesive composed of materials derived from non-fossil resources is a very important issue. In this study, only citric acid and sucrose were used as adhesive materials for particleboard. A water solution in which citric acid and sucrose were dissolved was used as an adhesive, and the manufacture of particleboard with a target density of 0.8 g/cm³ was attempted under a press condition of 200 °C for 10 min. The optimum mixture ratio of citric acid and sucrose and the optimum resin content was 25–75 and 30 wt%, respectively. The modulus of rupture (MOR) and the modulus of elasticity in bending were 20.6 MPa and 4.6 GPa, respectively. The internal bond strength (IB) was 1.6 MPa, indicating that the adhesive had excellent bond strength. The thickness swelling (TS) after water immersion for 24 h at 20 °C was 11.9 %. The board did not decompose even under more severe accelerated treatments. This meant that the adhesion had good water resistance. The MOR, IB and TS of the board were comparable to or higher than the requirement of the 18 type of JIS A 5908 (2003). Consequently, there is a possibility that a mixture of citric acid and sucrose can be used as a natural adhesive for particleboard.     

Improvement on the properties of gypsum particleboard by adding cement

Gypsum particleboard (GPB) has high thickness swelling (TS), high water absorption (WA), and low mechanical properties compared with cement-bonded particleboard. The properties of GPB were improved by adding cement. The experimental results showed that GPB with the added cement had good physical and mechanical properties compared with those of gypsum particleboard with no added cement. The TS and WA of gypsum particleboard with added cement were reduced by 10%. The mechanical properties of GPB, such as internal bond strength (IB), modulus of rupture (MOR), and modulus of elasticity (MOE), increased when the GPB was made with added cement. The properties of GPB improved relative to the quantity of cement added. With an increase of cement content from 5% to 10%, the TS and WA were reduced, and the IB, MOR, and MOE were increased. In contrast, the TS and WA increased and the IB, MOE, and MOR decreased when the cement content was increased from 15% to 30%. Thus the physical and mechanical properties of GPB were successfully improved when the added cement content was 10%.An outline of this paper was presented at the 47th Annual Meeting of the Japan Wood Research Society in Kochi, April 1997     

Reducing resin content and board density without adversely affecting the mechanical properties of particleboard through controlling particle size

Density and resin content are two factors that have a signifi- cant effect on the production cost of wood composite. However, particle size affects resin content and density, which suggests that the interaction of these three factors can be manipulated to reduce the board density and resin content of particleboard without adversely influencing its mechani- cal properties. Some mathematical functional forms based on resin con- tent, board density and slenderness ratio were regressed and an appropri- ate form was chosen. According to analysis of the results using SHA- ZAM 9 software, the exponential function best fit the experimental data. Finally, "indifference curves" of mechanical properties were illustrated and analyzed. The results indicated that negative effects of density or resin content reduction on mechanical properties could be compensated for by controlling particles’ slenderness ratio. Interestingly, increases in slenderness ratio compensated for the negative effects of decreases in resin content or board density on module of rupture (MOR) and module of elasticity (MOE). Moreover, this "compensation ratio" intensified as resin content or density decreased and/or as the MOR or MOE increased. On the other hand, reduction in slenderness ratio indicated a comple- mentary effect on reducing internal bond (IB) strength, a result of de- creases in resin content or density. Moreover, this "complementary ratio" was intensified as resin content or density decreased and/or as IB strength increased.     

Some of the properties of particleboard made from paulownia

The objective of this study was to determine some of the properties of experimental particleboard panels made from low-quality paulownia (Paulownia tomentosa). Chemical properties including holocellulose, cellulose, lignin contents, water solubility, and pH level of the wood were also analyzed. Three-layer experimental panels were manufactured with two density levels using urea–formaldehyde as a binder. Modulus of elasticity (MOE), modulus of rupture (MOR), internal bond strength (IB), screw-holding strength, thickness swelling, and surface roughness of the specimens were evaluated. Panels with densities of 0.65 g/cm³ and manufactured using a 7-min press time resulted in higher mechanical properties than those of made with densities of 0.55 g/cm³ and press times of 5 min. Based on the initial findings of this study, it appears that higher values of solubility and lignin content of the raw material contributed to better physical and mechanical properties of the experimental panels. All types of strength characteristics of the samples manufactured from underutilized low-quality paulownia wood met the minimum strength requirements of the European Standards for general uses.