不同介质对毛竹润胀效果的影响

Swelling of Phyllostachys edulis with different treatments

以毛竹Phyllostachys edulis为研究对象,采用不同浓度无水碳酸钠(Na_2CO_3),氢氧化钠(NaOH),氯化锌(ZnCl_2)水溶液(结合硝酸蒸煮)及去离子水对毛竹材进行润胀处理,以体积、面积变化率作为润胀效果的影响指标,观察毛竹宏观、微观构造的变化,探究在不同水溶液中毛竹材的润胀效果。结果表明:氢氧化钠水溶液与碳酸钠水溶液对毛竹的润胀效果较好;润胀效果随水溶液浓度的变化而变化,氢氧化钠水溶液浓度越低,润胀效果越好,而碳酸钠水溶液则相反,其中0.5 mol·L^(-1)氢氧化钠水溶液和1.0 mol·L^(-1)碳酸钠水溶液对毛竹的润胀效果最佳,体积增大率分别为9.69%和10.57%;直接使用氯化锌水溶液对毛竹进行润胀,润胀效果较差,但低浓度硝酸水溶液预处理可提高氯化锌水溶液对毛竹的润胀效果,其中500 g·L^(-1)氯化锌水溶液浸泡后(100 g·L^(-1)硝酸水溶液预处理)体积增大率为7.98%。同时,通过对润胀前后毛竹横切面不同区域面积的计算,显示在润胀过程中,纤维鞘区域面积变化幅度明显大于薄壁细胞区域面积变化幅度,说明毛竹润胀后体积变化的因素主要来源于纤维鞘分布面积的变化。

To determine the degree of swelling for bamboo (Phyllostachys edulis) in different aqueous solutions,bamboo samples were soaked in different concentrations of Na2CO3,NaOH,ZnCl2 (combined with HNO3 hydrothermal treatment),and deionized water.Changes in macro-and micro-structure were observed with the volume and area expansion rates used as evaluation indexes for the degree of swelling.Results indicated that NaOH and Na2CO3 both showed a good effect on the swelling of bamboo,meanwhile,the swelling effect of bamboo was proportional to concentration of Na2CO3,but inversely proportional to concentration of NaOH.Among the treatments,optimal volume increase rate were found with 0.5 mol·L^-1 NaOH (9.69%) and with 1.0 mol·L^-1 Na2CO3 (10.57%).Unsatisfactory swelling effect for swelling occurred when ZnCl2 was used alone,but pretreatment with a low concentration of HNO3 solution (500 g·L^-1 ZnCl2 with 100 g·L^-1 HNO3) improved swelling effect.Meanwhile,area of the bamboo in transverse sections before and after swelling showed that the area of fiber sheath distribution increased,but the area for parenchyma cell distribution after swelling was increased relatively small.Thus,changes in volume of bamboo after swelling was mainly due to changes in the fiber sheath distribution area.[Ch,6 fig.19 ref.].