Effect of Hydroxyethyl Methacrylate/Citric Acid Modification on Mildew Resistance of Bamboo
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摘要: 竹材由于内含淀粉等营养源而容易引起霉变,进而降低其外观品质和商品价值,限制竹制品的应用范围。笔者采用甲基丙烯酸羟乙酯/柠檬酸(HEMA/CA)的混合溶液浸渍竹材,使单体发生原位聚合—交联反应,从而提高改性竹材的防霉性能。研究结果表明,当HEMA的浓度为6%,且HEMA与CA的摩尔比为4∶1,交联温度为130 ℃时,竹材防霉改性效果最优,其对混合霉菌的防治效力达到100%。研究不同浓度、不同配比、不同热处理温度等不同处理条件下竹材的防霉性能及改性竹材防霉性能提高的主要原因;并通过红外光谱、热重分析和扫描电镜对其进行表征,结果说明:(1) HEMA与CA的原位聚合交联反应发生在竹材内部;(2)改性竹材的平衡含水率略有下降,而热稳定性并无明显提高;(3)改性前后竹材内的淀粉颗粒的形态基本保持不变。综上分析,推测改性竹材防霉效果的提升是由于侵入竹材的HEMA/CA生成的聚合物在营养源表面形成保护膜,隔绝了霉菌菌丝体的直接接触,从而达到防霉的效果。Abstract: Because bamboo contains starch and other nutrients,it is easy to get mildewed which reduces its appearance quality and commercial value and limits the application of bamboo products.In this study,the mixed solution of hydroxyethyl methacrylate (HEMA) and citric acid (CA) was used to impregnate bamboo.The monomers underwent in situ polymerization and crosslinking reactions,so as to enhance the mildew resistance of the modified bamboo.The results showed that the bamboo modification was optimized when the concentration of HEMA solution was 6%,the molar ratio of HEMA to CA was 4:1,and the crosslinking temperature was 130℃,which achieved 100% efficiency of mildew resistance.The concerned bamboo materials were characterized by IR,TGA and SEM.The results indicated that (1)in situ polymerization and crosslinking reactions between HEMA and CA occurred in bamboo;(2) The equilibrium moisture content of the modified bamboo decreased slightly,but the thermal stability was not improved significantly;(3) The morphology of starch granules in bamboo remained largely intact after the modification.In summary,it is speculated that the improvement of mildew resistance of the modified bamboo is due to the fact that the HEMA/CA polymers impregnate bamboo and form protective films on the surfaces of starch granules,which prevent the direct contact with mold mycelia and hence achieving the anti-mildew effect.
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Key words:
- Bamboo /
- Hydroxyethyl methacrylate /
- Citric acid /
- Mildew resistance
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