| Polyvinyl alcohol is a kind water-soluble and biodegradable of polymer materials,it is with high strength and high toughness,solvent resistance,air permeability,etc.,and it is widely used in the field of pharmaceutical packaging,water transfer printing,embroidery substrate carrier and medical since absorbing foamed material and anti-static film,etc.The film prepared by solution casting method has good precision,transparency and uniformity.Citric acid and sulfuric acid two methyl ester are used traditionally,their plasticizing effect is stronger than glycerol,but biodegradability of the film reduces.The crosslinking agent with glutaraldehyde has been crosslinked,but the water absorbability of the film reduces.Used by glycerol and propylene glycol as the plasticizer,surfactant twelve sodium dodecyl sulfate as foaming agent,water soluble of PVA/ starch films were prepared by solution casting method;combined with mechanical mixing method,PVA/ starch foam liquid were prepared by the twelve surfactant sodium dodecyl sulfate as foaming agent,PVA/ starch foam films by solution were prepared by casting method,applied to the water solubility of film fields such as embroidery substrate,water transfer printing.First of all,water-soluble PVA/starch films were prepared by casting method,using PET film instead of steel belt to realize flexible transfer of at low temperature,and adding starch and compound plasticizer glycerin and propylene glycol,surfactant,sodium dodecyl sulfate and defoaming agent etc.Results show that viscosity of solution increased with the decrease of temperature during the cooling process,starch can produce crystallization at 49 ?;during the heating process,viscosity of solution decreases with the increase of temperature.Viscosity of solution decreases with the extension of time,finally to keep constant at 50 ? after 150 minutes.The drying process was divided into three stages: uniform drying stage,slow drying stage,and gradually approaching 0 of volatile rate of stage.When drying at 50 ?,the drying rate in the first stage is close to the uniform velocity,and the velocity of moisture volatilization on the surface of the film is similar to the velocity of moisture diffusion from the inside of the film.The tensile strength of the film(thickness of 34 ?m)is 26.490 MPa,the elongation is 195.25%,under this condition,the tensile strength of film is the best.It is continuous,less particles,pore-free and no obvious wrinkles on the surface of the film,aging phenomenon of the starch did not happen in the glue.When the mass ratio of PVA and starch was 6:1,the amount of the plasticizer was 3%,the strength of film is highest,its value is 28.56 MPa,it can meet the requirements of the strength of the film.On this basis,water-soluble of PVA/starch foamed film were prepared by adding starch as nucleating agent,sodium dodecyl sulfate as foaming agent,carboxymethyl cellulose as thickening agent,and so on,adopted the method of foaming by foaming machine and coating.It can be seen that,foaming time is at 100 second,in the 10% of PVA/ starch glue prepared by 0.30% content of the SDS,The foam liquid can't stick the scraper,volume of foam is the largest.When the glue liquid concentration was 10%,the content of SDS was 0.30%,the content of CMC was 0.125%,the tensile strength of foamed film was the strongest,its value was 3.48 MPa,the tensile strength decreased by 70%,water soluble was longest,its value is 1.67 minutes,the bubble is small and uniform,the bubble diameter is about 100 ?m,form is closer to the round shape,which is an ideal technological condition. |
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