Study On The Structure And Properies Of MC Nylon6/TPU In-Situ Composites

In-situ nylon 6 composte were prepared through the anionic ring-opening polymerization ofε-caprolactam, taking full advantage of the low viscosity and strong polarity of theε-caprolactam solvent. The in-situ blends of MCPA6 and thermoplastic polyurethane elastomer(TPU) and polyether polyol (PEG) were prepared and studied respectively. Melt blends of PA6/TPU were perepared for comparison, through co-extrusion and the subsequent injection molding. A series of characterization by using FTIR,SEM,DMA,DSC,WAXD and PLM were carried out to investigate the changes in the chemical and supermolecular structures of PA6 as a result of blending.We discussed the side-reaction of ester and urethane groups in the anionic ring-opening polymerization process ofε-caprolactam. FTIR result indicated that the product of those side-reaction, acted as macroactivator to initiate MCPA6 chains to form copolymers. SEM result showed that copolymers were effectively improved the compatibility of MCPA6 and dispersed phase. The morphology of PA6/TPU melt blend were different from the in-situ ones. Dispersed phase in the in-situ blends had a finer and uniform dispersant than that in the melt mixing ones. More over, the notched impact strength and enlongation at break of in-situ alloy were greatly improved compared to melt blends, under the same content.At the same time, a series of MCPA6/thermoplastic polyester-based polyurethane elastomer(PAUR) blend were synthesized at different polymerization condition. The results indicated that sodium hydroxide content, percent of PAUR and polymerization temperature all had significant impact on structure and properties of MCPA6/PAUR alloy.We found that hard segments of thermoplastic polyether based polyurethane elastomer (TPUE) play a more important role in toughening MCPA6 than soft segments, by compared MCPA6/TPEU blends with MCPA6/PEG blends. As showed in SEM, it had hardly distinguished the dispersing phase from the MCPA6 matrix. In contrast, PEG shown very poor compatibility with MCPA6 matrix. The DSC results also accorded with those of blends with improved compatibility. Finally, we proposed a new toughening mechanism according to experimental phenomena. Consequently, a reasonable explanation for impact strength and enlongation at break which were obtained by incorporated only a small quantity of PAUR. The MCPA6/PAUR blends after quantitative stretched were studied. WAXD result indicated that hight enlongation reduced the density of hydrogen bonding and enhanced crystallinity of MCPA6 matrix.