Study On Preparation And Peformance Of Guar Gum And Gelatin Complex Films By Cross-linking Method

The source of natural polymer is very rich,they are biocompatibility and can be degraded by microorganisms,so they are more and more needed in daily life and scientific research.Polysaccharides and polypeptide are two extensive and improtant types of biopolymers.There are many hydrophilic groups on the backbone of the polymer chain,such as hydroxyl carboxyl and amino groups etc.These features help them possess a better hydrophilic property.But raw polysaccharides and protein materials often have the lower strength and poor water resistance,so it is very necessary to take some modification.this paper,guar gum which are common in polysaccharides,and polypeptide gelatin,are chosen as research objects.Guar gum and gelatin composites were synthesized by two modification methods,and the mechnial properties and practical applications of the composites were studied.Main tasks as follows:In this study,an superhydrophilic/underwater superoleophobic membranes for oil-water separation are prepared by coating a layer with guar gum(GG)and citric acid(CA)on a stainless steel mesh(SSM)via a one-step dip-coating method.Citric acid was added as a cross-linking agent.FTIR and TGA tests indicated that the esterification reaction occurred between the GG and CA at 100°C to form a insoluble film.SEM and XPS showed that the surface chemical comp osition and the surface morphologies of mesh have been changed after coating.The contact angle test illustrate the surfaces of h CAGG@SSM are superhydrophilic and underwater superoleophobic.The separation experiments were measured by self-made equipment and the results showed the h CAGG-coated mesh exhibits exceptional separation property.A flux of 14000 L·m^-2·h^-1 and separation efficiency>98.0%are achieved while using the modified mesh.Moreover,it has ultra-low oil adhesive properties and can be easily cleaned.The mesh retain its oil-water separation performance after 10separation cycles.Furthermore,the mesh exhibits superior anti-salt properties and can maintain the separation performance while the p H value was between 4 and 10.A novel gelatin-based nanocomposite was created by adding NA-montmorillonite(Na-MMT)as a reinforcing material and ethylene glycol diglycidyl ether(EGDE)as a cross-linking agent.FTIR indicated that EGDE had reacted with gelatin to form a network structure.SEM revealed that the surface of pure gelatin films are smooth.After Na-MMT was added,there were some pore apperaed in the surface.TGA test showed that thermal stability was improved by adding the Na-MMT and EGDE.The gelatin composites exhibited a lower swelli ng ratio,lower water solubility and lower water vapor permeability compared with pure gelatin,whic indicated the water resistance property was ipmproved.Results of tensile test indicated that the addition of NA-MMT and EGDE caused increase in the tensil e strength(TS)and decreased the elongation at break(EAB),which leading to stronger films than neat gelatin.