| Poluvinyl alcohol(PVA), polyacrylic acid(PAA) and starch are the three kinds of sizing agents. The sizing property of polyvinyl alcohol(PVA) is excellent, but it is difficult to biodegree, having environmental problem.The moisture absorption and viscosity of polypropylene was serious, which is often used as an auxiliary material.The starch slurry consumption accounted for more than 70% of the total consumption of sizing agent.Compared with the native starch, the sizing performance of modified starch was significantly improved.The mature of starch modified method is chemical modification method, the chemicals reagent by cutting, molecular rearrangement, oxidation or introducing substituent effect on raw starch, changed the structure of the starch, improve performance of starch slurry.The use of chemical reagents to produce the inevitable environmental pollution has attracted the attention of researchers. In order to solve this problem, we studied the method of enzymatic hydrolysis of starch to produce modified starch.In this paper, the structure performance, process of starch modified with ?-amylase,size performance and sizing property of enzymolysed starch were discussed. We could obtain a modified products with good sizing performance.Firstly, the key factors affecting the catalytic performance of ?-amylase(include p H value, reaction temperature, reaction time and substrate concentration), and the relationship between the dose of ?-amylase and the viscosity of starch were discussed,and designed the process of producing enzymolysed starch.Secondly,the viscosity of S-9.0m Pa was prepared,and the size performance,sizing property and size film performance were studied. The following aspects are studied:(1)The optimum reaction conditions of the ?-amylase were studied. And the best modification process were following :Raw starch concentration was 15%.The dose of?-amylase(starch dry weight ratio) was 1.17%~2.29%.The p H value is 6.0.The temperature of reaction was 60?, and the time of reaction is 50 min.The inactivation process of ?-amylase were following:The p H value is 4.0.The temperature of reaction was60?, and the time of reaction is 15 min.(2)The viscosity of S-9.0m Pa was prepared,and the basic physical properties of starch were tested.(3)Infrared spectrum method is used to study the structure of the enzymolysed starch,the result shows that the enzymatic hydrolysis of starch in the 3330.1 cm-1, 2928 cm-1,1146.1 cm-1, 1646.2 cm-1, 1000.8 cm-1 has obvious absorption peak. They represent the O-H, C-H and C=O stretching vibration and bending vibration C-H, and the Spectrum of transmitted light intensity increased.It could conclude that the original starch surface and internal alcohol-based, hydroxyl, carbonyl, C-O-C chemical bonds had broken.Observation of the microstructure of starch by using scanning electron microscope,the result shows that the shape of the enzymolysed starch was kept constant, but the surface distribution of the particles was small.Amylase was hydrolyzed in the amorphous region of starch, and the shape of starch was complete.(4)The viscosity heat stability of starch slurry was more than 90%.Selecting oxidized starch as contrast sample and the anticoagulation of slurry to sink, the cotton roving adhesion and film performance were tested.The result shows that the anticoagulant retrogradation, adhesion and film properties of roving are excellent, and the enzymolysed starch could meet the requirements of warp sizing slurry.(5)The sizing experiments were carried out on the 14.6tex pure cotton yarn by using the enzymatic hydrolysis of starch and oxidized starch. It could conculde that the enzymatic hydrolysis of starch can improve the abrasion and fracture of raw yarn strength,significantly reducing raw yarn hairiness.And it can be used as warp sizing slurry.In this paper,... |
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