Star Nylon 6, The Star Nylon 12 Synthesis And Characterization

Star-shaped polymers are the simplest non linear polymers. Compared with the corresponding linear macromolecules, a consequence of this architecture is a reduction of their viscosity both in solution and in the melt. It allows for processing at lower temperatures and pressures as well as for processing higher molecular weight polymers. Reduced viscosity allows also for improved injection moulding. These properties are important especially for high-melting polycondensation polymers. Moreover, Reduced viscosity allows also for manufactured articles with complex configuration and decrease expenditure of energy for processing. In this paper, star-shaped nylon 6 and star-shaped nylon 12 were prepared respectively in the presence of trimesic acid by hydrolytic polymerization of caprolactam and laurolactam. The main conclusions are as follows:1. In the presence of trimesic acid, star-shaped nylon 6 and star-shaped nylon 12 were prepared respectively by hydrolytic polymerization of caprolactam and laurolactam. The structure of polymerization product were ascertained by the spectra of FTIR, ¹H-NMR.2. Mechanical properties and rheological properties of star-shaped nylon 6 and star-shaped nylon 12 were determined. The properties of star-shaped nylon 6 and star-shaped nylon 12 were compared with PA6 and PA12 respectively. Relationship between structure and property was studied. Tensile strength, bending strength, Izod impact strength and elongation at break decreased with increasing content of trimesic acid. Compared with the corresponding linear nylon, star-shaped nylon has significantly decreased viscosity in solution and in the melt ,yet most of the mechanical properties are retained. Equilibrium torques of star-shaped nylon was also significantly decreased. Star-shaped nylon have the balance of processing vs. material properties.3. The melting crystallization behavior and thermogravimetry analysis of star-shaped nylon 6 and star-shaped nylon 12 were investigated by DSC and TG. The results showed that the T_m and T_c of star-shaped nylon 6 and star-shaped nylon 12 decrease obviously with increasing the content of tremisic acid and the crystallization rate of star-shaped nylon 6 and star-shaped nylon 12 werr slower than that of the corresponding linear nylon. The results of thermogravimetric (TG) analysis showed that The stability of star-shaped nylon was as good as that of the corresponding linear nylon.4. The dynamic mechanical properties of star-shaped nylon 6 and star-shaped nylon 12 were investigated by dynamic mechanical analyzer(DMA). The results showed the storage modulus(E') of star-shaped nylon and the corresponding linear nylon are different below the glass transition temperature. Compared with the corresponding linear nylon, the a relaxation temperature of star-shaped nylon 6 and star-shaped nylon 12 decreased with increasing the content of trimesic acid,βandγrelaxation temperature of star-shaped nylon 6 and star-shaped nylon 12 were similar.αrelaxation activation energy of star-shaped nylon 6 and star-shaped nylon 12 respectively were abtained.5. Non-isothermal crystallization processes and kinetics of star-shaped nylon 6 star-shaped nylonl2 were investigated by DSC. Peak temperature of the DSC curves gradually decreases with increasing cooling rate. Half-crystallization time, t_1/2, decreased by exponentially with increasing cooling rate, thus the crystallization rate was enhanced with the increasing of cooling rate. The Avrami index of star-shaped nylon 6, n₁, fluctuated from 2.41 to 2.61 with different cooling rates. The Avrami index of star-shaped nylon 12, n₂, fluctuated from 1.73 to 2.19 with different cooling rates. Diffusion activation energy of nylon 6 and star-shaped nylon 6 are -269.0KJ/mol,-231.5 KJ/mol. Diffusion activation energy of nylon 12 and star-shaped nylon12 are -249.1KJ/mol,-239.3 KJ/mol.