影响羟丙基瓜尔胶HPG性能的因素

Factors for influencing the performances of modified guar HPG

在瓜尔胶改性,即制备羟丙基瓜尔胶的过程中,降低水不溶物含量与保持粘度之间存在着矛盾,因此必须对反应物的加量和反应条件进行优化试验。研究了影响羟丙基瓜尔胶产品性能的因素,考察了改变碱的加量、水的加量、反应温度、反应时间及环氧乙烷的加量对改性瓜尔胶水不溶物含量的影响。试验结果表明,影响瓜尔胶改性产品性能的因素很多,其中的关键因素是碱的加量,碱的加量越大,水不溶物含量越低,但相应地改性瓜尔胶粘度受到的影响也越大,因此为了得到较低的水不溶物含量和较高的粘度,碱的加量应控制在10％以内;反应物中必须加入一些水,以保证瓜尔胶稍微膨胀,但是过多的水会使瓜尔胶增粘,导致改性瓜尔胶粘度下降,合适的醇水比例为3:1-4:1左右;环氧乙烷的加量越大,水不溶物含量越低,但增加到一定量时对水不溶物含量降低不明显,却会降低产品的粘度,所以较适宜的环氧乙烷加量为10 mL;反应温度和反应时间也是控制产品质量的重要因素,合适的反应时间为4h,合适的反应温度为60℃,在这样的条件下能使瓜尔胶改性产品的水不溶物含量从25％降到8％以下。

There are contradictions between reducing the water insoluble matter content and maintaining the viscosity, during the process of modification of guar gum, or preparation of the mixed derivatives of polygalac-tomannans. Laboratory tests are conducted to investigate the factor for influencing the performances of modified guar products, i. e. , the dosage of alkali, water and epoxyethane, temperature and time to the content of water insoluble matters. Tests results show that the key factor is the dosage of alkali, the more alkali added, the lower content of insoluble matters, yet the viscosity of HPG is also negatively influenced. To achieve a lower content of water insoluble matters and higher viscosity simultaneously, the dosage of alkali should be controlled within 10%. A suitable proportion of alcohol to water is required, say 3:1 to 4:1, to inflate guar gum and maintain the viscosity of HPG at the same time. In addition, the temperature and reacting time are also important and should be controlled to 4 hours and 60℃ respectively.