Starch has good adhesion to hydrophilic natural fibers, also has a certain film forming ability, low price, rich resources, and is very common in warp sizing. However, the starch slurry sizing performance is not ideal, such as the poor thermal stability of the slurry, the film is not hard and brittle wear, etc., need to use physical or chemical methods to make the starch degeneration or mixed with other pulp to improve the sizing effect and Expand its use. Guar gum is a degradable natural polysaccharide polymer that is soluble in cold and hot water and is widely used in the food industry to improve the performance of starch. Viscosity tester for the determination of the viscosity of starch, the biggest advantage of the additives for textile pulp is very similar to the structure of cellulose, has direct nature to cellulose, but also biodegradable, thermal stability.
A dry weight of 3.0 g of corn starch was precisely weighed, and 0.015 g of guar dry weight was placed in an aluminum sample measuring tank, and 25.7 ml of distilled water was added. The solid mass concentration of the system is 10.5%, wherein the mass fraction of guar gum/starch is 0.5%. The sample measurement tank was placed in an RVA-Ezi viscosity tester and placed in a stirrer at a rotational speed of 160 rpm. Run the temperature control software, that is, the starch slurry is heated to 50°C to start timing. After one minute, raise the temperature to 95°C (to 4.81 min) at 11.80°C/min, hold 2.5 minutes (to 7.31 minutes), and then cool down at 11.8°C/min. To 50 °C (11.12 min), keep warm to 13 min. The starch paste viscosity was read once every half minute during this period and the starch gelatinization curve was plotted. The solid mass concentration of the system was unchanged, and the mass fraction of guar gum/starch in the mixed sample series was increased by 0.5% from 0.5% to 7.5% and the gelatinization curve was determined.
The analysis by the viscosity tester found that the viscosity of the low concentration pure guar gum solution was not very high, but the low concentration of guar gum caused a large change in the RVA viscosity curve of the guar gum/starch mixed system. With the increase of the mass fraction of starch in guar gum, the peak viscosity of the mixed system continued to increase; the gelatinization temperature of the starch remained unchanged at the initial stage, then increased, and decreased at a later stage; the viscosity of the mixed slurry at the low temperature continued to increase, but decreased. The tendency of the low temperature viscosity to increase over time. These phenomena indicate that the interaction of guar gum with water or with starch molecules affects the gelatinization and viscosity behavior of the mixed system. The addition of guar gum to the starch helps to reduce the low temperature rejuvenation rate of the starch slurry, but it is not conducive to the high-consistency and low-viscosity sizing process. It is necessary to denature the guar gum and reduce its molecular weight. This is our next research work.
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