The Influence Of Molecular Weight And Different Degree Of Hydrolysis On Biodegradation Of PVA

PVA(Poly vinyl alcohol) is considered as one of the most excellent slurry.Using less or none of PVA becomes the development trend of slurry because it can contaminate the environment.We have difficulties to use the size which has none of PVA in a long time.First of all,environmental size which can substitute PVA drastically has not been produced at home and abroad presently.Second,the prices of polycyclic size and starch graft copolymer which are produced successfully are high.Research on the degradability of PVA has been developed by all of the country recently.The influences of every fact on the biodegradability become the focus due to the better way which can degrade PVA by biology.But rearserch on the influence of the structure of PVA on the biodegradability is little.This word is concentrated in influences of structure on biodegradation of PVA.BOD and COD are the major way to appraise biodegradability of the Polymer Material.The word discussed major method of BOD and COD,and chooses the one which is best for this word.Then we choose the appropriate condition of the experiment and the point to make up stabilized solution for example dilution water,vaccinal water and dilution inoculation water on BOD by experiment.By measuring the BOD/COD value of five different kinds of PVA,we can gain the influences of every fact on the biodegradability.Then we measure the oxygen demand of them in ten days.For the sake of appraising the biodegradability of PVA comprehensively,we decide to adopt a way of spectrophotometry method which can research the progress and mechanism of biodegradation in the condition of degree and speed of biodegradation.So it can reinforce the method that so you say powerfully.We can make sure the wavelength,the compound of colorant,the dosage of colorant and react time by experiment.Then we measure the image of four different kinds of PVA between time and concentration of PVA.From the experiment,we can conclude molecular weight and different degree of hydrolysis is important facts to affect the biodegradation of PVA.The PVA of smaller molecular weight is excel the bigger one as biodegradability,the PVA of alcoholics incompletely is excel the absolutely one as biodegradability.But it goes against the biodegradability if the degree of hydrolysis was low.In principle we can conclude the magnitude of hydrogen bond force is dependence on the molecular weight.If the molecular weight is big,the hydrogen bond force is big too.The hydrogen bond force will affect water-solubility and the ability which microbe come into the inner molecule.These two sides have great influence on biodegradation of PVA.The degree of hydrolysis is the measurement of the number of hydroxyl and carbethoxy.The existence of carbethoxy debases the hydrogen bond force for one side.For the other side,as a hydrophobic groupe,it can induce worst for the water-solubility of some little molecule.This goes against the biodegradation of PVA.Those two sides work together.The biodegradation mechanism of PVA is the major molecule chain of PVA degrades as smaller segments in the function of the cell ectoenzym.Then the smaller segment comes into the inner of cell. The carbethoxy change into ascetic acid in the work of Cytoplasm ester enzyme.And it has more metabolized.So the time is hysteretic.