辛胺改性海藻酸钠薄膜的制备及理化性能研究

Preparation and Physicochemical Properties of Sodium Alginate Film Modified by Normal Octylamine

目的为了提升海藻酸钠薄膜的力学性能和疏水性能。方法以1–(3–二甲氨基丙基)–3–乙基碳二亚胺(EDC)/N–羟基琥珀酰亚胺(NHS)为催化剂,将辛胺(OA)通过酰胺化反应共价连接到海藻酸钠的分子中,利用疏水烃基链分子之间的“缔合作用”来提升海藻酸钠薄膜的力学性能,并且降低其水溶性。通过流延的方法制备辛胺改性海藻酸钠膜(OASA),探究辛胺的接枝率与成膜性能的关系,以及辛胺添加量对膜的力学性能、水溶性、水蒸气透过率、颜色及热力学性能的影响。辛胺改性海藻酸钠的分子结构通过红外光谱(FTIR)、核磁共振氢谱(1HNMR)得到证明;改性海藻酸膜的结构通过X射线衍射(XRD)和扫描电镜(SEM)进行分析。结果在辛胺的接枝率为19.94%以下时,可以得到均匀透明的薄膜;与纯海藻酸钠薄膜相比,辛胺改性膜的拉伸强度和断裂伸长率分别提升了23.1%和35.5%;热力学数据表明,在最终加热温度为700℃时,残留量增加,最大失重速率对应温度下降,膜的热力学稳定性增加;辛胺改性膜的含水量、水溶性和水蒸气透过率比纯海藻酸钠薄膜分别下降了37.2%、17.5%和81.3%。结论通过共价改性在海藻酸钠的分子中引入长烃基链的方式,是一种有效提升膜材料理化性能的策略。

The paper aims to improve the mechanical and hydrophobic performance of sodium alginate film.In this paper,n-octylamine(OA)was covalently connected to sodium alginate molecule through amidation reaction by using EDC/NHS as catalyst in order to improve the mechanical and hydrophobic performance of sodium alginate film.The mechanical properties of sodium alginate film were improved and its water solubility was reduced by the"associa-tion"between hydrophobic molecules.The grafting rate of octane amine and the film forming performance was investi-gated,and the effects of the addition amount of octyl amine on the mechanical properties,water solubility,water vapor transmittance,color and thermodynamic properties of the film were investigated.The molecular structure of octyl amine modified sodium alginate was confirmed by FTIR and 1HNMR.The structure of modified alginate film was analyzed by XRD and SEM.The results showed that uniform transparent films can be obtained when the grafting rate was less than 19.94%.Comparing to the pure alginate film,the strength(TS)and elongation at break of the modified film were in-creased by 23.1%and 35.5%,respectively.The thermodynamic data showed that the thermodynamic stability of the film increased with the increase of residual amount at the final heating temperature of 700℃and the decrease of the maximum decomposition rate temperature.Comparing to native alginate film,water content,water solubility and water vapor transmittance of the OA modified alginate film decreased by 37.2%,17.5%and 81.3%,respectively.It is an effective strategy to improve the physical and chemical properties of film materials through covalent modification to introduce long hydrocarbon chain into sodium alginate.