The Research Of CMC Compounds Starch Adhesive

Starch is a non-toxic and environmental-friendly raw material which is cheapand easy to get. It is used in adhesive industry with low-cost, non-pollutingadvantages. However, there are drawbacks on original starch regardless of its physicalor chemical properties. This study improve the initial viscosity of original starch,shorten its drying time, increase bond strength, while improving other properties. Theprocess is adopting oxidation, gelatinization treatment to the original starch, and thencomplexing with CMC. At last, the adhesive achieve industrial application standard.At first, the oxidation and the gelatinization process of the starch is discussed andstudied. By analyzing and contrasting, potassium permanganate is selected as oxidantand sodium hydroxide is selected as gelatinization agent. The effect of starchconcentration, reaction temperature, reaction time to its viscosity is inspected and thebest process parameters is got. The microstructure changes before and after oxidationand gelatinization is compared through infra-red spectra which is got before and afteroxidation and gelatinization process.The results show that viscosity increased continuously with the increasing ofstarch concentration in the solubility range.The reaction temperature is selected65℃.In the infra-red spectra can be seen that little amount of hydroxyl is oxidized intocarboxyl. Part of starch chain units change into straight-chain from ring afteroxidation, and after gelatinization the hydrogen bonding has been damaged.After determining process parameters such as temperature and concentration, theeffects of polymers on modified starch adhesive is studied.Orthogonal design testmethod is used to inspect the results which sodium tetraborate,CMC consumptionaffect on several key indicators of the adhesive.The reasons why the amount of eachcomponent influence the property is discussed.And the best ratio range of eachcomponent is obtained through comprehensive consideration.The orthogonal design study drew the following conclusions:1)Under the test-setcondition, the impact of compounding polymers is most obvious to the apparent viscosity.In a certain range,viscosity increases while the CMC increases.2) Under thetest-set conditions, the amount of CMC and sodium tetraborate affect the drying timesignificantly, while reaction time is weak. The CMC and sodium tetraborate areplayed to the role which reduce and improve the drying rate.3) Under the conditionsof the test set, the amount of CMC and sodium tetraborate affect the bond strengthsignificantly, and other factors do less.The bond strength at first increase and thenreduced while the reaction time increases.Excellent and modified starch adhesive is made based on the ratio got fromorthogonal test while also need adding relative ingredient.The better dosageproduction formulations is as follows starch50g,potassium permanganate0.5g,sodium hydroxide5g,CMC10g, sodium tetraborate3g, carbamide and alcohol is in itsmoderate.Such products have many advantages such as high initial viscosity,betteradhesive force,short drying time,non-toxic non-polluting to environment etc. There isa very broad application prospect in industrial production.