Study On The Hydrolysis Of Poly 6-hydroxycaproic Acid

Due to poly 6-hydroxycaproic acid own good biodegradability and biocompatibility,it is applied to study of biomedicine and tissue engineering field widely.The final degradation products of poly 6-hydroxycaproic acid are CO2 and H2 O,and no toxicity to human body and no harm to health.It can be used as drug delivery carrier material,a cell and tissue culture,fully degradable plastic surgical suture and so on.Poly 6-hydroxycaproic acid have a good mutual solubility with polymer material such as PE,PP,ABS,AS,PC,PVAC,PVB,PVE,PA,crude rubber and so on,and can prepared to a variety of excellent properties of copolymers or blends,so in recent years,the study about poly 6-hydroxycaproic acid and its copolymers have been more appreciated.As a representative of degradable materials,the quantity demanded of poly6-hydroxycaproic acid will be larger.Meanwhile,discarded polyester material will bring serious environment problems.Although poly 6-hydroxycaproic acids own a good biodegradability,in the natural environment,the degradation rate is very low,and also can cause the waste of resources and environmental pollution.Facing to society problems that resource depletion,energy shortage,environmental pollution,for junked poly6-hydroxycaproic acid material we should make reasonable recycling.Poly6-hydroxycaproic acid material can be converted to low molecular weight products by chemical recycling method,and the products can be recycled as raw material.So the polyester material can put out the maximum recycling value.This paper studies the hydrolysis mechanism and optimum condition that poly6-hydroxycaproic acid under different alkalinity conditions of sodium hydroxide,sodium carbonate,sodium bicarbonate.In the whole reaction system,choose glycol as solvent.The qualitative analysis of hydrolysis products was realized by the machine of gas chromatography-mass spectrometry,and the quantitative analysis of hydrolysis products was realized by the machine of gas chromatograph.The major achievements as follows:1.The greater the alkalinity(such as sodium hydroxide),the greater the concentration of OH-,and affinity groups [OH-] direct attack on poly 6-hydroxy acid ester group structure,make the ester bond cleavage reaction occurs,generating small molecule 6-hydroxy acid;Reaction process conditions are relatively mild,In the collector constant heating magnetic stirrer can complete disaggregation with the temperature of 100 ?.2.The smaller the alkalinity(such as sodium carbonate,sodium bicarbonate),the smaller the concentration of OH-,and in the early stage of the reaction,the affinity group [-OCH2CH2OH] was dominant,and the probability of occurrence of alcoholysis reaction is great,and alcoholysis reaction and alkaline reaction are mutually promoting in the entire reaction system;Reaction process conditions are relatively harsh,must be fully depolymerization at 180? sealed autoclave.3.Finding out the analysis method of hydrolysis products: Eliminating the interference that the effects of water on the measuring results by complexation extraction.The experimental results showed that the extraction rate of products could reach above 97%,Under the conditions that oil and water phase ratio of 1,mixing time of 1h,the mixing temperature of 25,used TOA as extrantant.4.The optimum technical conditions of sodium hydroxide: sodium hydroxide /poly 6-hydroxy-acid molar ratio of 4.4:1,glycol / poly 6-hydroxy-acid molar ratio of6.5:1,catalyst of 0.1g,the reaction temperature of 100 ?,reaction time of 2h,the depolymerization rate of poly 6-hydroxy-acid reaches 96.06%,the productivity of6-hydroxy-acid reaches 84.58%.5.The optimum technical conditions of sodium carbonate: sodium carbonate /poly 6-hydroxy-acid molar ratio of 1.3:1,glycol / poly 6-hydroxy-acid molar ratio of6:1,catalyst of 0.1g,the reaction temperature of 180~190 ?,reaction time of 1h,the depolymerization rate of poly 6-hydroxy-acid reaches 92.11%,the productivity of6-hydroxy-acid reaches 78.13%.6.The optimum technical conditions of sodium bicarbonate: sodium bicarbonate /poly 6-hydroxy-acid molar ratio of 3:1,glycol / poly 6-hydroxy-acid molar ratio of 3:1,catalyst of 0.1g,the reaction temperature of 180 ?-190?,reaction time of 1h,the depolymerization rate of poly 6-hydroxy-acid reaches 98.53%,the productivity of6-hydroxy-acid reaches 90.38%.7.On the basis of laboratory research,enlaging the process design of the optimum technical conditions of sodium bicarbonate,and determining the design parameter,and forming the process flow chart(PIDs)of the whole process.8.Using the hazard and operability analysis(HAZOP)method to analyse the causes,the consequance,and control measures of risk factors in the process engineering,and putting forward the safety control measures of processing installations.