Polymer by anionic polymerization of epsilon-caprolactam with the presence of bisphenol-A polycarbonate: Characterization and properties

This thesis deals with the anionic polymerization of epsilon-caprolactam in the presence of polycarbonate by using a Grignard reagent as initiator. Previously a "liquid-solid" method was used and the so-formed polymer was found to have strong tensile properties and good adhesion to glass fiber. In this research a change has been made to a "liquid-liquid" system; comparison between the two methods on the basis of tensile properties showed that the "liquid-liquid" method was preferred.; To investigate the possible reaction route, model reactions were conducted and evidence has shown that the activating species came from the interaction between polycarbonate and caprolactamate anion. GPC, FTIR and NMR spectroscopic results were used to support the proposed reaction route. The final material was also characterized by SEM to show its single-phase morphology; solubility properties were investigated in various solvents and thermal stability examined by TGA results. Diphenyl carbonate (DPC) was used to synthesize pure nylon 6 to be used as a comparison polymer. The polymer made from polycarbonate has better thermal stability than pure nylon 6 in both dry and wet conditions.; The effect of environmental (i.e. oil bath) temperature during polymerization (Toil) was studied in the range of 95°C--160°C. The original reactive mixture contained 75g epsilon-caprolactam/0.75g polycarbonate (SPP)/10mmol iso-Bu-MgCl. Various properties of the nascent polymers were measured and compared. Monomer conversion changed little (over 95%) with different Toil's while intrinsic viscosity data in 90% formic acid was higher for polymers made at higher Toil's. In the polymers made at T oil's above 147°C there was gel formation. Melt viscosity data showed the same trend as intrinsic viscosity with the polymer made at 160°C showing the highest value. There was a decrease in degree of crystallinity for polymers when Toil increased. Both DSC and X-ray showed the same trend. The alpha crystal structure was the major form in this series of polymers while the one made at 160°C contained more gamma structure than the others. It has been found that at lower Toil's, there were more voids formed in the nascent materials. This led to the poorer tensile properties and higher moisture absorption for polymers made at lower Toil's (under both "dry" and "wet" test conditions).; The influence of the type and amount of polycarbonate and Grignard reagent was also studied. An optimal ratio between polycarbonate and Grignard reagent has been found in order to have higher monomer conversion and rate of polymerization, i.e. 8 mmol initiator/g polycarbonate. Results have shown that more polycarbonate in the reaction system led to faster rate of polymerization and lower intrinsic viscosity. Melt complex viscosity was used to show the reinforcement of final polymer by the existence of polycarbonate blocks. There was a decreasing trend in melting temperature and degree of crystallinity as the concentration of polycarbonate increased while the ones using DPC showed the reverse trend due to the existence of gamma form in the nascent polymers. The difference between iso-Bu-MgBr and iso-Bu-MgCl and the difference between two polycarbonates with different MW on various final properties were also evaluated.