Preparation And Property Investigation Of Antibacterial Bio-based Polyurethane Composite Packaging Film

Polyurethane film is widely used in domestic food,medical health,clothing and other fields,and people’s requirements for its functional application are also increasing rapidly.Polyurethane is currently consumed in a huge amount in various industries,and the use of environmentally friendly and renewable bio-based raw materials to replace petroleum-based raw materials to prepare polyurethane has also become a research hotspot.In this paper,it was proved that polyhydroxylated bio-based polyols(ESO-polyols)were prepared by using epoxidized soybean oil(ESO)as raw material,using polyethylene glycol(PEG)to open its ring,using FT-IR and ~1H-NMR analysis.Measuring its hydroxyl value to be 127 mg KOH/g.And bio-based polyols were used instead of petroleum-based polyols to react with isocyanate(IPDI)to synthesize bio-based polyurethane(BPU),its Mw measured by GPC is about 22000,so as to achieve the purpose of saving energy and protecting the environment.By adjusting the R value and the film-forming temperature during casting and curing,BPU films with different R values and film-forming temperatures were prepared.The effects of R value and temperature on the properties of BPU films were studied through mechanical testing,DSC and TGA testing,water contact angle testing,moisture and oxygen permeability performance testing,SEM testing and so on.With the increase of R value and film forming temperature,the mechanical strength,water contact angle and microphase separation degree of BPU films gradually increased,the transparency,oxygen permeability and moisture permeability coefficient gradually decreased,and the barrier properties and thermal stability gradually improved.In order to make BPU film better used in food preservation packaging,the antibacterial agent hexahydro-1,3,5-tris(hydroxyethyl)-s-triazine(TNO)was mixed into BPU by chemical bonding method to obtain antibacterial BPU-TNO composite film,and prepared BPU-TNO composite film with different TNO content to study its effect on performance.The test results show that with the increase of TNO content,the mechanical properties,hydrophobicity,thermal stability and barrier properties of BPU-TNO composite film are effectively improved.With the increase of TNO content,the light transmittance of BPU-TNO films gradually decreased.The antibacterial effect of the antibacterial BPU-TNO composite film on Escherichia coli,Staphylococcus aureus,black mold and Penicillium were tested by the zone of inhibition method.The results showed that the inhibitory effect on Escherichia coli,Staphylococcus aureus,Black mold and Penicillium relatively best when the content of antibacterial agent was 0.8%.The antibacterial effect of the antibacterial BPU-TNO composite film on Escherichia coli is better than that on Staphylococcus aureus;the antibacterial effect on Penicillium is better than that on black mold.The carrot samples were packaged with BPU-TNO composite film for shelf-life test to evaluate their food packaging preservation ability.The results showed that the color and odor of carrot slices packaged with BPU-TNO composite film were always better than those of carrot slices in the bare state and those packaged with commercial PLA/PHBV film,and the quality remained above 90%on the 8th day.Finally,the hydrolytic degradation of the BPU-TNO composite film shows that the reaction between the ester group of the soft segment of the BPU molecular chain and the hydroxide ion destroys the cross-linked network structure and destroys the surface structure of the BPU-TNO composite film,making the BPU-TNO composite film is degraded.