【摘要】 <正> 木材主要由纤维组成^**。在针叶树材中占整个木材体积的90～95％^[9],阔叶树材占50—80％^[9]。纤维胞壁的层次结构对木材的性质和工业加工、利用有很大影响。纤维胞壁是由构造和物理、化学性质不同的许多层次组成,常包括初生壁（P）、次生壁（S）和相邻两细胞间的胞间质。初生壁微纤丝排列无定向。次生壁是胞壁主要部分,含大量纤维素,具强度向异性。它分为外（S₁）、中（S₂）及内（S₃）三层;其中S₂层最厚,约占全壁厚度70％以上,是构成胞壁的主体。微纤丝环绕细胞轴呈螺旋状排列。微纤丝（或纤丝）角是指S₂层中微纤丝和细胞轴之间所构成的角度^[4,8,14]。更多还原

【Abstract】 The mean microfibril angle of Pinus massoniana was measured by meansof diffractometer technique using（002）reflection.The methods of X-raydiffraction are easy to measure.The wood samples can be free from themodification as a result of chemical treatment.The comparison between themean microfibril angle measured by iodine staining and the values obtained by（002）reflection was studied.The former is somewhat smaller than the latter.Because the mean microfibril angle of Pinus massoniana is smaller than 20°,M₄₀ agrees well with M_0.6t.Since the longer the tracheid the steeper will bethe pitch of the helices of the microfibrils to the longitudinal axis of the fiber,the mean microfibril angle of latewood is smaller than the earlywood,and themean value of sapwood is larger than the heartwood.更多还原