Preparation Of Composite Films Using Alkali-soluble Hemicellulose From The Chemical Fiber Industry

The price-rising of cotton pulp led the chemical fiber factory to use relatively cheap wood pulp as raw material.The hemicellulose dissolved in alkali impregnated wood pulp produced a large amount of alkaline waste liquid rich in hemicellulose.Therefore,it is of great significance to analyze the composition of waste liquid and make use of it with high value for solving the environmental problems brought by waste liquid and increasing the economic benefit of enterprises.The main components of waste liquid from chemical fiber factory were studied.The results showed that the concentration of sodium hydroxide was 10.67 g/L and the concentration of hemicellulose was 98.60 g/L.The results of acidolysis showed that in every100 parts of hemicellulose,the content of monosaccharide is 76.0,glucose is 13.2,mannose is7.8,galactose is 1.7,arabinose is 1.4.And the waste liquid basically does not contain the benzene alcohol extract and the lignin.The number-average molar mass and weight-average molar mass of hemicelluloses is 1.19×10~4g/mol and 1.59×10~4g/mol respectively.In order to make full use of alkali-soluble hemicellulose which has high degree of polymerization and high purity in the waste liquor,the alkali-soluble hemicellulose with high purity was isolated from the waste liquor of chemical fiber plant by ethanol precipitation method.In this paper,the grafted hemicellulose(ASH-g-PCL)was prepared from alkali soluble hemicellulose,and then the biodegradable biofilm was obtained by blending it with polylactic acid(PLA).The results show that ASH-g-PCL can improve the moisture permeability and toughness of the polylactic membrane and reduce the light transmittance and tensile strength of the polylactic acid film.Adding glycerol,diatomite and nano-silica to the film,it was found that the tensile strength,toughness,oxygen resistance and moisture permeability of polylactic acid film were obviously improved by adding 10wt.%glycerol.The tensile strength,elongation at break,water vapor transmittance and oxygen transmittance are 12.71MPa?25.59%?502.9 cm~3*?m/(m~2*d*kPa)and 348.75 g/m~2*24h respectively,but at the same time,the transmittance of the films is also decreased.The tensile strength,elongation at break and water vapor transmittance of the film added 5wt.%diatomite are 15.08MPa?73.11%and174.56 g/m~2*24h respectively.The tensile strength,elongation at break and water vapor transmittance of the film added 5wt.%nano-silica.are 16.94MPa?69.73%and 68.88g/m~2*24h respectively.It can be seen that adding diatomite can improve the tensile strength,toughness and moisture permeability of polylactic acid film,while nano-silica can improve the tensile strength,toughness and moisture barrier of PLA film.It is found that the structure of the films prepared by blending ASH-g-PCL with PLA is significantly different from that of pure PLA.From the SEM photos of different film sections,it can be seen that ASH-g-PCL has significant pore-forming function in PLA materials,and the density of pores increases with the increase of ASH-g-PCL content.The addition of glycerol will continue to increase the mesh structure and pore density.The results show that ASH-g-PCL,glycerol,diatomite and nano-silica can improve the properties of PLA film,and are expected to be used in the production of food atmosphere modified packaging film materials.In this study,the polymer ASH-g-PAS and AH-g-PAS was prepared from alkali soluble hemicellulose(ASH)and acrylated hemicellulose(AH)under the condition of free radical copolymerization,respectively.And the recycled films with high strength,high transmittance and high oxygen resistance were obtained.The oxygen resistance,light transmittance,micromorphology and mechanical properties of the above four films were investigated.The photo-transmittance and oxygen resistance of the films F-0?F-0.1AH?F-0.2AH?F-0.3AH?F-0.4AH prepared with the ratio of 0.05g/ml?0.1g/ml?0.15g/ml?0.2g/ml were also compared.The results show that the oxygen transmittance of the films F-0 is 4.38 cm~3*?m/(m~2*d*kPa),the OTR of the F-0.1AH decreases to 2.49 cm~3*?m/(m~2*d*kPa).And the OTR of the film decreased from 0.61 cm~3*?m/(m~2*d*kPa)to 0.25 cm~3*?m/(m~2*d*kPa)when AH was added from 0.1 g to 0.4 g.It can be seen that AH can significantly enhance the oxygen resistance of the films than ASH,and the greater the feed ratio,the better the oxygen resistance of the films were abtained.The OTR of F-0.1AH-10%is 0.27 cm~3*?m/(m~2*d*kPa),which is 55.55%lower than that of F-0.1AH,indicating that the performance of oxygen resistance is improved significantly.The tensile strength of F-0.1AH is 36.85 MPa.which is 35.18%higher than F-0,indicating that ah can significantly increase the tensile strength of the film.F-0.1AH-10%tensile strength is 79.08 MPa.Compared with F-0.1AH,the tensile strength increases 114.6%and the elongation is almost zero.The results show that the addition of 10wt.%sorbitol can greatly improve the strength of the film,but also decrease the toughness significantly.The effect of three factors on the tensile strength of the polymer film was established by using the response surface method.The optimum condition that ratio of 0.17g/ml,reaction temperature of 55.10?and reaction time of 81.99 min were determined by model analysis.The predicted tensile strength of the prepared membrane material is 55.1MPa.The results showed that the reaction temperature and the reaction time were more obvious than the influence of the feed ratio on the tensile strength of the film.The results showed that the reaction temperature and the reaction time were more obvious than the influence of the feed ratio on the tensile strength of the film.