蒙脱土对纤维素基吸湿衬垫结构与性能的影响

目的在羧甲基纤维素钠(CMC-Na)与壳聚糖(CS)基材中添加纳米蒙脱土(MMT),制备安全无毒、具有良好吸水性的海绵衬垫,可用于鲜肉的保鲜包装。方法将不同比例的MMT添加到CMC-Na和CS混合溶液中,冻干后采用氯化钙交联得到海绵衬垫,测定衬垫在水中的溶胀率和可溶物含量以优化配比,然后测定最优衬垫的吸湿速率、红外光谱、形貌、压缩强度以及色差等。结果当MMT质量分数为5%时,衬垫在水中的溶胀率最高,可溶物含量较低,且与空白对照品相比,由于MMT在高分子基材表面形成大量微米级团聚粒子,所以其比表面积增大,吸湿速率加快。同时,由于MMT良好的力学强度,且与CMC-Na和CS基材结合良好,因此MMT的添加大大提高了衬垫的压缩强度。加入MMT后,虽衬垫的颜色有所加深,但肉眼观察并不明显。结论 MMT的加入可改善CMC-Na/CS衬垫的性能,促进其在鲜肉包装中的实际应用。

Effects of Montmorillonite Addition on the Structure and Properties of CMC-Na/CS Sponge Absorbent Pad

A novel CMC-Na/CS sponge absorbent pad with the addition of MMT was prepared for fresh under stirring. Then, the mixtures were freeze-dried and crosslinked using CaCl2 to obtain the sponge pads. The swelling ratio and soluble content of the sponge pads in water were tested to determine the optimal ratio of MMT, followed by performing moisture adsorption rate measurement, FTIR, SEM, chromatism analysis and compressive strength test on the resultant sponge pad. The optimal addition ratio of MMT was 5%, which gave the highest swelling ratio and relatively low soluble content to the sponge pad, compared with other samples. CMC-Na/CS sponge pad containing 5% MMT (CMC-Na/CS/MMT-5) showed faster moisture adsorption compared to the blank pad (CMC-Na/CS). The compressive strength of CMC-Na/CS/MMT-5 was also higher than that of CMC-Na/CS due to the excellent strength of MMT and the good interfacial adhesion between MMT and polymer matrix. Although the color of the sponge pad was slightly deepened with the addition of MMT, it was hardly visible to naked eyes. Addition of 5% MMT improved the properties of CMC-Na/CS sponge pads, thus accelerating their practical applications in fresh meat packaging.