Investigation On The Chain Extension Of Polyamide 6 With Bis(2-oxazoline) And The Blending Modification Of Polyamide

In the first part of this paper, two chain extenders, 2,2' -bis(2-oxazoline) (BOZ) and 2,2' -(1,3-phenylene)bis(2-oxazoline) (PBO), were synthesized by a more simple and moderate route. The optimum technology of synthesis two chain extenders have been found through the orthogonal experiment. For the preparation of 2,2' -bis(2-oxazoline) (BOZ), the results showed that the solution of ethanolamine in ethanol was slowly dropped in a solution of diethyl oxalate in ethanol with the molar ratio of reactants was 2.5:1, the yield of N,N ' -bis(2-hydroxyethyl)oxamide was up to 94.1%; The yield of N,N' -bis(2-chloroethyl)oxamide could reach 73.7% when the toluene was used as solvent and the molar ratio of reactants was 3:1; the overall yield of 2,2'-bis(2-oxazoline) could reach 82.3% when benzene was used as water-removing agent with the molar ratio of reactants was 2.25:1. For the preparation of 2,2' -(1,3-phenylene)bis(2-oxazoline) (PBO), the optimum prescription and technology was 1,3-dicyanogen benzene:2-aminoethanol=1:3 (mole ratio), catalyst content was 2.5%mol to cyano,reacting time was 4 h and reacting temperature was 130℃, the product yield reached 63.6%. Furthermore, the two chain extenders were used in the study of the chain extension of Polyamide. The effects of the amount of the chain extenders, reaction time and temperature on the intrinsic viscosity([η]), terminal carboxyl content(CV) and terminal amine content were studied, and the physics properties of chain-extended Polyamide 6 were investigated. Furthermore, the actual kinetic model of chain extension of Polyamide 6 with 2,2' -(1,3-phenylene)bis(2-oxazoline) (PBO) was also investigated. The coupling results showed that there existed an optimal dosage of chain extender, lack of which caused deficiency of chain extension and excess of which led to more blocking reaction. For the chain extension of Polyamide 6 with BOZ, the optimum amount of chain extender in PA6 was 1.156wt.% (1.5 times as much chain extender as theoretical amount), at the same time, the carboxyl content of chain-extended products decreased to 40% of initial carboxyl content of PA6, correspond to the intrinsic viscosity of PA6 increased to 1.636 dl/g while the control sample was 1.384 dl/g. For the chain extension of Polyamide 6 with PBO, the optimum amount of chain extender in PA6 was 0.773wt.% (theoretical amount), at the same time,the carboxyl content of chain-extended products decreased to 51.6% of initial carboxyl content of PA6, correspond to the intrinsic viscosity of PA6 increased to 1.787dl/g while the control sample was 1.632 dl/g. The effect of temperature on the chain extension reaction time accorded with the Arrhenius exponential formula. The chain-extended products were dissociated at high temperature with long time, due to the ester-amide group in the PA6 chain occurred other reactions at high temperature.The effect of BOZ on the chain extension of Polyamide was better than that of PBO, due to the different diffusion effect of two bis-oxazolines in melting PA. The mechanical properties of chain-extended PA6 showed a quite increasing in wet condition, because the interaction between water and oxazoline ring resulted in the increasing intermolecular action of PA6. The chain-extended PA6 showed a depression in crystallinity due to the introduction of the ester-amide group in the PA6 chain. The actual kinetic model of chain extension of Polyamide with PBO lead to almost good fits between theoretical cures with the experimental results.In the second part of this paper, the preparation of Super-tough Polyamide and the structure and properties of barrier material of Polyamide/Polyolefin were also investigated. In chapter 2, the results showed that the brittle to ductile transition of PA6/(POE/PP)-g-MAH blends occurred when the mass fraction of (POE/PP)-g-MAH in the blends was 20wt.%, the mechanical properties of blends were optimum at the same condition. The SEM results showed that the dispersed phase in PA6/(POE/PP)-g-MAH exhibits a smaller size and a more uniform distribution with the increasing mass fraction of (POE/PP)-g-MAH in blends. The barrier material of HDPE/MPA was prepared by two screw extruder, where the high viscosity nylon(MPA) was prepared by chain extension with BOZ and PBO, HDPE matrix was chosen by the rheology of forming barrier materials. The obvious layer structure of the barrier materials was observed by SEM.