山桐子木材材性研究

Wood properties of Idesia polycarpa

【目的】对山桐子木材的解剖性质、物理力学性质及抽提物进行较为系统的研究,以全面了解山桐子木材的材性状况。【方法】以四川省古蔺县35年生山桐子为研究对象,按照相关的国家标准进行试验材料采集、年轮宽度测定和木材主要物理力学性质测定,采用永久切片法和离析法进行木材解剖性质的测定与分析,利用无水乙醇和乙酸乙酯对木材进行抽提,并对抽提物成分用气相色谱与质谱联用仪(GC-MS)进行分析。【结果】山桐子木材为散孔材,平均年轮宽度3.94 mm,最大宽度可达13.0 mm,属于优质速生用材树种。山桐子纤维形态指标平均值分别为:长度1420.12μm,宽度32.51μm,腔径14.40μm,双壁厚5.57μm,长宽比43.68;导管形态指标平均值分别为:长度594.34μm,宽度89.86μm,腔径72.22μm,双壁厚7.58μm,长宽比6.96。山桐子的气干密度为0.44 g/cm 3,质地轻软,干缩率小,从气干到绝干,径向、弦向、轴向干缩率分别为1.61%,3.52%和0.44%;从湿材到绝干,径向、弦向、轴向干缩率分别为3.29%,6.91%和0.89%。山桐子木材端面、径面、弦面硬度的平均值分别为3377.39,1814.09和1903.64 N,顺纹抗压强度为35.07 MPa,抗弯强度为64.52 MPa。山桐子木材心材、过渡层、边材无水乙醇抽提物的质量分数分别为0.25%,0.75%和1.15%,其中最主要成分为2,2′-亚甲基双-(4-甲基-6-叔丁基苯酚);山桐子木材心材、过渡层、边材乙酸乙酯抽提物的质量分数分别为0.56%,1.29%和0.75%,其中主要成分为2,4-二叔丁基苯酚和γ-谷甾醇,此外还含有少量的醇类和酯类物质。【结论】山桐子木材呈黄白色-浅黄褐色,质地轻软,木材尺寸稳定性较好,易干燥,但抗压和抗弯强度较小,内含物含量较少,适用于制造纸浆或纤维板、胶合板、刨花板等人造板材,也可作为实木装饰材料,但不适宜用作承压构件和弯曲结构构件。

【Objective】The wood properties of Idesia polycarpa were comprehensively investigated by systematical analysis on the anatomical characteristics,physico-mechanical properties and extract composition.【Method】The 35-year-old I.polycarpa wood in Gulin,Sichuan was selected for material collection and measurement of growth ring width and physico-mechanical properties according to national standards.Anatomical characteristics were analyzed by microtomy and fibre segregation process.The ethyl acetate and anhydrous ethanol extracts were prepared and their constituents were identified using Gas Chromatograph-Mass Spectrometer(GC-MS).【Result】I.polycarpa wood was diffuse-porous wood with average ring width of 3.94 mm and the maximum width of 13.0 mm,indicating that I.polycarpa was a high-quality and fast-growing timber species.The average fibre length,width,lumen diameter,double cell wall thickness,aspect ratio and cavity width ratio were 1420.12μm,32.51μm,14.40μm,5.57μm and 43.68,respectively.Those values for vessel were 594.34μm,89.86μm,72.22μm,7.58μm and 6.96,respectively.The average air-dry density of I.polycarpa wood was 0.44 g/cm 3,suggesting that I.polycarpa belonged to soft wood.From air drying to oven drying,the radial,tangential,axial and volume were reduced by 1.61%,3.52%and 0.44%,respectively;while the reduction rates from wet to oven-dry were 3.29%,6.91%and 0.89%,respectively.The average hardness of the end-section,radial-section and tangential-section were 3377.39,1814.09 and 1903.64 N,respectively.The parallel-to-grain compressive strength and bending strength were 35.07 MPa and 64.52 MPa,respectively.The ethanol extract contents for heartwood,transition layer and sapwood were 0.25%,0.75%and 1.15%and the main components were 2,2′-methylenebis-(4-methyl-6-tert-butylphenol).The ethyl acetate extract contents for heartwood,transition layer and sapwood were 0.56%,1.29%and 0.75%and the main component was 2,4-Di-tert-butylphenol and(3beta,24 S)-stigmast-5-en-3-ol.Small amounts of alcohols and esters were also identified in extracts.【Conclusion】I.polycarpa wood was yellowish-white to yellowish-brown in color,light and soft in texture and easy to dry,while the compressive strength,bending strength and extract contents were low.I.polycarpa wood was suitable as decoration material,pulping material and artificial boards such as fibreboard,plywood,and particleboard.It was not suitable for compression or curved structures.