两性淀粉的取代度与吸湿保湿性能关系的研究

Study of relation between the degree of substitution of amphoteric starch and the ability of moisture absorption,moisture retention

以淀粉为母体,3-氯-2-羟丙基三甲基氯化铵和氯乙酸为改性剂,通过清洁的半干法工艺合成出不同羧甲基取代度高的水溶性两性淀粉,并对其吸湿、保湿性能进行研究。结果表明,两性淀粉的吸湿、保湿性能均随着羧甲基取代度的增加而增强。当RH为81%,阴离子取代度大于0 08时,两性淀粉的吸湿性与甘油相当,而保湿性在RH81%和RH38%下均优于甘油;两性淀粉的吸湿速率随着羧甲基阴离子含量增加而提高。初步探讨了两性淀粉的吸湿动力学,水分子在两性淀粉中的扩散属于non-Fickian类型。

Water-soluble amphoteric starch with different degree of substitution (DS) of carboxymethyl group was prepared by hemi-dry process,from starch as starting material and modified by treating with 3-chloride-2-hydroxypropyltrimethyl ammonium chloride and chloroactic acid.The capability of moisture absorption and moisture retention was investigated.The results show that the moisture retention and moisture absorption were boosted up with the increasing content carboxylmethyl group incorporated.Moisture absorption of amphoteric starch is as good as that of glycerine when relative humidity (RH) 81 %,and DS of carboxymethyl group is up to 0.081.The moisture retention capability of amphoteric starch was better than that of glycerine when RH is 81 % as well as RH is 38 %.For a given DS of cationic group,the rate of moisture-absorption increased with the increasing of content of carboxyl-methyl group incorporated.The moisture absorption kinetics of amphoteric starch was discussed and the diffussion of water molecule in amphoteric starch looks likely to be non-Fickian type.