Research On The Modification Of Wood Adhesive Made From Oil-tea Cak

Camellia oleifera cake is a by-product of oil extraction from Camellia oleifera seeds,which has the conditions and potential for preparing adhesives.It can not only reduce the dependence of the artificial board industry on synthetic resin adhesives based on petrochemical resources,but also has the advantages of environmental protection,renewability and wide source of raw materials compared with formaldehyde-based adhesives,which is of great significance to the development of biomass adhesives.In this paper,Camellia oleifera cake is used as raw material to study the degradation of Camellia oleifera cake,Degradation and crosslinking combined modification and protein polypeptide stabilization and enhancement of Camellia oleifera cake adhesive.The chemical composition,curing property,water resistance,heat resistance and other physical and chemical properties of the modified adhesive are studied,and the bonding performance of the prepared plywood is tested.The results are as follows:（1）Camellia oleifera cake adhesive was prepared by thermal degradation,acid degradation,alkali degradation and enzyme degradation respectively.The experimental results showed that the degradation effectively broke the structural bonding bonds and interactions between protein polypeptide chains,and exposed more hydrophobic groups,which was conducive to the improvement of water resistance.At the same time,the breaking of protein spheroid structure exposed active groups and generated active sites.The viscosity of hot degraded Camellia oleifera cake adhesive was higher（708.3 m Pa·s）,while the viscosity of acid and enzyme degraded Camellia oleifera cake adhesive was lower（311.6m Pa·s and 324.3m Pa·s）.All the treatment methods meet the national standards for wood-based panels and decorative panel bonding strength requirements of 0.7MPa,acid degradation of Camellia oleifera cake adhesive strength is the highest,1.36MPa.The bonding strength of the Camellia oleifera cake pulp adhesive after enzymatic treatment was the lowest,which was 0.82MPa.The crystallisation degree of the adhesive is higher,and the bonding property is better.Alkali degraded Camellia oleifera cake adhesive has relatively high reactivity,it is an effective degradation method for Camellia oleifera cake.（2）The effects of NaOH addition on the hydrolysis degree of Camellia oleifera protein,the reaction capacity of formaldehyde in the degradation solution,the viscosity and the bonding property of the adhesive were investigated.The experimental results showed that when the amount of NaOH was less than 8%,the degradation degree increased rapidly at first and then gradually.When the alkali content is 5%,the degradation degree reaches 25.18%,which indicates that NaOH can effectively degrade the cake and produce active groups and active sites.Before adding NaOH,the formaldehyde reaction capacity was as low as 13.1 mg·g^-1.After the addition of alkali（5%）,the formaldehyde reaction capacity at this stage increased most significantly,reaching 44.2 mg·g^-1.When the amount of NaOH was increased by8%,the increase of formaldehyde reaction capacity slowed down.The wet wood breaking rate of the Camellia oleifera adhesive prepared by alkali degradation was more than 60%.According to the results of degradation degree,viscosity,formaldehyde reactivity and bonding strength,the degraded protein has higher reactivity,greater cohesion strength,better sizing property and excellent bonding property when the addition of NaOH is 7%.（3）In order to solve the problem of poor initial viscosity and stability of alkali-degraded Camellia oleifera adhesive,respectively mixing the Camellia oleifera cake meal with defatted soybean protein,separated soybean protein,oligopeptide and casein,and then preparing the adhesive by alkali degradation and crosslinking.The experimental results showed that:The modified adhesive curing reaction temperature is lower,the heat release is significantly increased,the initial viscosity and stability of the adhesives are increased,and the application period is shortened.The whole flexibility of the modified adhesive is enhanced,Cross-linked products can be better elastic contact and regular arrangement,the crosslinking structure and the crosslinking density are further strengthened,the cured adhesive layer forms a dense and compact network structure,bonding strengths of the modified adhesives were all met the strength requirements of Class II plywood in GB/T 17657-2013（≥0.70MPa）.The adhesive strength of oil tea cake modified with defatted soybean protein was the highest,reaching 0.93MPa.