Abstract:

Calcium alginate fibers nonwoven fabrics which could absorb plenty of water and then transformed into gels were prepared by using two-step chemical modification methods. Calcium alginate fibers nonwoven fabrics were dipped into hydrochloric acid aqueous solution and sodium hydroxide solution using ethanol as the solvent. The comprehensive properties of gels derived from calcium alginate fibers nonwoven fabrics were the best, when concentration of hydrochloric acid solution was 0.05%-0.1%(mass) and concentration of sodium hydroxide solution was 0.008%-0.016%(mass). Under this condition, absorbing water capacity of calcium alginate nonwoven fabrics increased by 1.45 times after being modified chemically, and the ratio of preserving water capacity to absorbing water capacity of calcium alginate nonwoven fabrics increased by 10.67 times after modification. Thickness, mass of per unit area, air permeability and breaking strength of modified calcium alginate nonwoven fabrics changed a little before absorbing water, but the size of modified calcium alginate nonwoven fabrics after absorbing water adequately improved about 3 times. It indicated that the reason for formation of gel was related to structure and properties of calcium alginate fibers but not to fabric texture. At the stage of treatment with hydrochloric acid solution, the formed “egg-box” structure in calcium alginate fibers, and the crystal structure of these fibers were damaged partially and the degree of crystallinity and Ca²⁺ content of these fibers were decreased, but ester bond formed in these fibers. At the stage of treatment with sodium hydroxide solution, the formed ester groups changed into carboxyl groups and hydroxyl groups and intermolecular forces of fibers weakened for this change. Crosslinking degree and intermolecular forces of modified calcium alginate fibers were adjusted to appropriate states, so plenty of water molecules were absorbed by modified calcium alginate fibers and the absorbed water molecules could interact with fibers molecules in the form of hydrogen bond. For these reasons, modified calcium alginate fibers nonwoven fabrics changed into gels as soon as they were put in water.

Key words: calcium alginate fibers, nonwoven fabrics, gels, biomass, preparation, chemical modification

摘要：

采用HCl水溶液和NaOH乙醇溶液，通过两步法对海藻酸钙纤维针刺非织造布进行水凝胶化改性，研究改性工艺对样品结构与性能的影响，并探究改性机理。结果表明，HCl水溶液的最佳浓度为0.05%～0.1%（质量），NaOH乙醇溶液的最佳浓度为0.008%～0.016%（质量），此时改性样品的遇水凝胶性能最佳，吸水量提高了1.45倍，但厚度、断裂强力等物理性能变化不大。HCl处理破坏了纤维的“egg-box”结构和结晶结构，降低了其结晶度和Ca²⁺含量，但在纤维分子间形成了酯键。NaOH处理使新形成的酯键水解，削弱纤维分子间的作用力，使得大量水分子扩散进入到纤维大分子之间，并通过氢键作用形成三维网络结构，从而转变成凝胶体。

关键词: 海藻酸钙纤维, 非织造布, 凝胶, 生物质, 制备, 化学改性