Polymerization And Process Of Copolyamide PA 6/66

Polyamide has good overall performance and forming property, it plays an important role in the actual production. The tenacity of polyamide is not good enough and the melting point is somewhat high, which restricts the application range of it. In our study, we used caprolactam and nylon 66 salt as raw materials to synthesize copolyamide 6/66. We took use of solid state polymerization(SSP) method to improve the viscosity of copolyamide 6/66 to 4.0 and studied the relationship between molecular weight,melting point and monomer ratio. And we used injection molding and melt spinning method to study the technology and property of copolyamide 6/66.It was found that as the content of nylon 66 salt increases,the melting point of copolyamide decreases. When the SSP temperature is 165 ℃,the relative viscosity of copolyamide 6/66 increases as reaction time increases while its melting point changed little. The cold crystallization time of copolyamide 6/66 is shorter compared to that of polyamide 6. And as the content of nylon 66 salt decreases, the cold crystallization time decreases.Copolyamide 6/66 with relative viscosity of 4.0 was chosen as the study obeject. And we found that copolyamide 6/66 melt is a pseudo-plastic flow with non-Newtonian index between 0.55-0.69 during 270℃ to 290 ℃.The shearing rate sensitivity of copolyamide melt tends to decrease with higer temperature. The flow activation energy of copolyamide 6/66 is 42.96~78.98 k J.mol-1 when the shearing rate is between 115~3686s-1, and the temperature sensitivity of melt tends to decrease with higher shearing rate. In a broad frequency range, the Storage Modulus of copolyamide 6/66 is lower than that of polyamide 6, which means that the elastic deformation ability of copolyamide 6/66 is better.The Loss Modulus of copolyamide 6/66 is higher than that of polyamide 6, which means that the deformation of copolyamide 6/66 is larger under stress and the damping effect is better. Both the Storage Modulus of copolyamide 6/66 and polyamide 6 decreases as the temperature increases, the Sotrage Modulus of copolyamide 6/66 is lower than that of polyamide, and its damping effect is better when the temperature is low.When the charing barrel temperature was well controlled within 260~275 ℃ and the injection pressure was 75 MPa during the injection molding process of copolyamide 6/66,molding effect was good. The impact strength of breaking elongation of the splines we got was respectively 9.68 k J.m-2 and 340%.During the melt spinning process of copolyamide 6/66 filament, copolyamide 6/66 had good extrusion stability at 280~300℃.When the processing temperature was 280℃ with a screw speed of 15r/min and a spinning speed of 10m/min and a drawing ratio of 3.68, the filament we got showed good overall performance. The breaking strength, knot strength and hook joint strength was respectively 432.4MPa, 125.4MPa and 328.98 MPa.During the melt spinning process of copolyamide 6/66 multifilament,when the processing temperature was well controlled within 275-280℃ with a spinning speed of 130m/min and a drawing ratio of 3.46, copolyamide had good spinning stability. The breaking strength and breaking elongation of copolyamide 6/66 filament was respectively 3.84 c N/dtex and 16.7%.