【作者】 陈玲；

【导师】 江泽慧；

【作者基本信息】 中国林业科学研究院 ， 木基复合材料科学与工程， 2009， 博士

【摘要】 马尾松(Pinus massoniana Lamb.)是我国亚热带地区特有的、资源丰富的乡土树种,是我国松树资源中分布最广、数量最多、用途广泛的主要树种之一,是我国重要用材树种。开发结构胶合板可以适应木材原料变化的现状,充分利用人工林资源,提高木材利用率。大力发展用速生树种制造高强度、高弹性、耐气候、耐室外四季变化的自然条件的结构胶合板,对我国具有现实意义。本研究以马尾松不同厚度单板制结构胶合板为研究对象,对其进行性能进行研究,探讨单板厚度对性能的影响。本文首先研究了马尾松单板的物理力学性质、吸水厚度膨胀率及润湿性,之后对马尾松不同厚度单板制造的结构胶合板的力学性能、尺寸稳定性及胶合性能进行了研究。本研究得出以下结论:(1)随着马尾松单板厚度的增加,其密度及顺纹弹性模量和静曲强度有增加的趋势,单板的也逐渐增加。(2)随着马尾松单板厚度的增加,其润湿性变好。在相同厚度的情况下,松面的润湿性优于紧面,顺纹方向的润湿性优于横纹,早材优于晚材。(3)随着组成单板厚度增加,板坯的中间层的升温速率逐渐升高。(4)随着涂胶量增大,胶合板的胶合强度增大,当达到某一值之后,趋于稳定或略有下降。在涂胶量相同情况下,随着单板厚度增加,胶合强度降低。而且随着单板厚度增加,较优涂胶量增大。(5)随着热压时间增加或热压温度升高或胶合板密度的升高,马尾松胶合板的吸水厚度膨胀率逐渐降低。随着组成单板厚度的增加,吸水厚度膨胀率逐渐升高。(6)随着热压时间延长或热压温度升高或胶合板密度增加,胶合强度,静曲强度及弹性模量均逐渐增加,之后趋于稳定或略有下降。(7)得出马尾松结构胶合板的较优工艺为:涂胶量为A类(1.7mm)350g/m2,B类(3.2mm)400g/m2,C类(5mm)和D类(7mm)均为500g/m2;热压时间为1.0-1.2min/mm,热压温度为140℃左右,胶合板密度为0.75g/ cm3左右。(8)芯层厚度百分比对弹性模量与静曲强度影响较大。芯层厚度百分比越小,顺纹弹性模量和静曲强度逐渐越高,横纹弹性模量和静曲强度越低。(9)通过数字散斑法进行应变分析得出,在胶合强度拉伸测试中,发生最大变形的区域在裂隙处,即在裂隙处破坏。在弯曲测试中,从位移场相关系数的图可以看出,其相关系数均在0.95以上,有很好的相关性。因此,利用数字散斑的方法,可以从微小的应变过程分析和推断木材破坏位置。(10)马尾松结构胶合板大板弯曲刚度近似服从Weibull分布。(11)采用不同标准测试MOE和MOR的结果存在差异。(12)建立了马尾松结构胶合板快速预测模型,预测结果与ASTM D3043方法D的结果相关性较好。(13)单位面积上涂胶量随组成单板厚度增加逐渐减少。厚单板组坯的结构胶合板的顺纹弹性模量及静曲强度高。可以使用在对顺纹弹性模量及静曲强度要求高的地方。而且随着单板厚度的增加,组坯形式可以更加多样以满足不同的需要。因此厚单板制造结构胶合板优势明显,有发展前景。更多还原

【Abstract】 As specific and resource-rich native tree species in subtropical regions in China, Masson pine (Pinus massoniana Lamb.) is the most extensively distributed, it is the largest in number, and its use is extensive. It is the important commercial species in China. The development of the structural plywood can meet the changes in the situation of wood raw materials, the plantation resources can be used well, and the timber utilization can be improved. It has great meaning to develop structural plywood with high strength, high flexibility, resistance to climate, and resistance to outdoor conditions with fast-growing tree species. In this study, the performances of structural plywood made of Masson pine veneer with different thickness are researched. The effect of the veneer thickness on the performances of the plywood is discussed.In this study the physical and mechanical properties, thickness swelling after soaked in water, and the wettability of veneer are studied at first. Then the mechanical properties, dimensional stability, and bond performance of structural plywood made of Masson pine veneer with different thickness are researched.The conclusions are as follows:(1) With the increase of the thickness of veneer, veneer density increase, the MOE and MOR parallel to grain also increase.(2) With the increase of the veneer thickness, the wettability becomes good. When the veneer thickness is same, the wettability of loose side is better than that of the tight side, the wettability parallel to grain is better than that perpendicular to grain, the wettability of early wood is better than that of late wood.(3) With the increase of the veneer thickness, the heating rate of middle layer increases.(4) The bond strength increases with the increase of the glue spread. When the glue spread reached some value, the bond strength gets stable or decreases slightly. When the glue spread is same, the bond strength decreases with the increase of the veneer thickness. The thicker the veneer is, the more the glue spread is. (5) The water absorption thickness swelling decreases with the increase of the hot-press time, temperature or plywood density. The thickness swelling after soaked in water increases with the increase of veneer thickness.(6) With the increase of the hot-press time, temperature or plywood density, the bond strength, modulus of elasticity (MOE) and modulus of rupture (MOR) increase gradually, then get stable or decrease slightly.(7) The best technology is as follows: the glue spread of A-type veneer (1.7mm) is 350g/m2, B-type (3.2mm) is 400g/m2, C-type (5mm) and D-type (7mm) are 500g/m2; hot pressing time is 1.0-1.2min/mm, hot-pressing temperature is about 140℃, the plywood density is about 0.75g/cm3.(8) The percentage of core layer thickness has great effect on the MOE and MOR. The smaller the percentage of core layer thickness is, the larger the MOE and MOR parallel to grain are, the lower the MOE and MOR perpendicular to grain are.(9) The Digital Speckle Correlation Method (DSCM) is used to study the tiny strain of the Masson pine structural plywood. In the bonding strength test, In the middle region where the deformation is larger, the largest deformation is not coherent. That is affected by lathe-check. When the bonding strength tests are carried out, the region where the deformation is largest is at the lathe-check. In the bending test, from the correlation coefficient diagram of the displacement field, we can notice that the correlation coefficient is above 0.95, the correlation is good. Therefore, the place where the timber is damaged can be analyzed and deduced from the tiny strain process by using DSCM.(10) The data of he bending test of big panel similarly obey Weibull distribution.(11) The performances of Masson pine structural plywood that are tested according to different testing methods are different.(12) The prediction model of MOE of Masson pine structural plywood is built. The predicted value is correlated with the results of ASTM D3043 method D.(13) With the increase of veneer thickness the glue spread in unit area decreases gradually. The MOE and MOR parallel to grain of the structural plywood made of thick veneer is high. That can be used in the situation where the demand of MOE and MOR parallel to grain is high. With the increase of veneer thickness the assembly is various to meet different demand. The advantage of structural plywood made of thick veneer is obvious. The structural plywood made of thick veneer has great foreground.更多还原