Development of Acrylic Copolymer Modified Corn Starch Adhesive II

2.1.3 Effect of AA-AAm Copolymer Dosage on Viscosity (see Figure 3)

As can be seen from FIG. 3, the viscosity of the system increases as the amount of AA-AAm copolymer increases. Because AA and AAm are both very water-soluble, they can be easily polymerized into polymers. Copolymers contain hydrophilic groups such as -COOH, -COO-, -CONH2, which easily form hydrogen bonds with water molecules. The carbon chain structure in the copolymer forms a network structure between the molecules through association and cooperation, so that the macromolecular chains further aggregate to form a huge hydrodynamic volume centered on the polymer, which increases the viscosity of the system. However, the amount of AA-AAm copolymer cannot be too large, otherwise the system gels and loses its viscosity. The mass fraction of polymer is controlled at 06% and 8%.

2.1.4 Effect of Starch Dosage on Viscosity

Increase the amount of starch, the viscosity of the system increases. Experiments have shown that it is appropriate to control the starch mass fraction at around 25%.

2.2 Effect of Value on Adhesive Stability (see Figure 4)

As can be seen from Figure 4, the stability of the system increases as the pH increases. Because of the addition of ammonia water, the carboxyl group (-COOH) in the copolymer is converted into ammonium salt of carboxylic acid (-COO-NH4+), which increases the negative charge density of the copolymer, increases the repulsion between the copolymers, and reduces the aggregation. At the same time, it also increases the hydrogen bonding interaction with water and increases the water solubility of the AA-AAm polymer, thus increasing the stability of the system.

2.3 Effect of the amount of copolymer on the bond strength (see Figure 5)

As can be seen from FIG. 5, the adhesive strength increases with the increase of the amount of AA-AAm copolymer, and reaches the maximum when the mass fraction of AA-AAm copolymer is 8%) and then decreases. Because the introduction of a small amount of polar groups in the adhesive increases the adsorption of the glue on the corrugated cardboard, thereby increasing the bonding strength. However, when the amount is too large, the probability of reaction between AA and AAm increases, the molecular mass of the copolymer increases, and the penetration of glue into corrugated paperboard decreases, resulting in a decrease in adhesive strength. In addition, the bonding strength is improved and the drying speed is also improved.

3 Conclusion

Through experiments and production practices, AA-AAm modified corn starch adhesive has good adhesive strength, drying speed, stability and fluidity, uniform coating, easy gluing, easy use, and the bonding strength exceeds the national standard requirements. The 0.06MPa quality standard can meet the actual needs of production.

(Author/Ye Chuping Wang Niangui College of Chemistry and Materials Science, Hubei University)

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