Effects Of Molecular Weights On Properties Of Nylon 12

Nylon 12 with its excellent physical and mechanical properties has been widely used in the automotive industry,the chemical industry,electronic industry,medical devices and other areas.With the rapid development of 3D printing,the importance of nylon 12 becomes more and more prominent.Therefore,the study of the effects of molecular weights on the properties of nylon 12 has a distinctive feature of the times.This topic is the starting point and the relevant work has been carried out.The following results are obtained:(1)The polymerization process and the synthesis of different molecular weights nylon 12 were studied by hydrolysis and ring opening polymerization using laurolactam as raw material.The results showed that six different molecular weights of nylon 12 were synthesized by using reaction temperature 260 ~ 270 ℃,reaction time 6 hours and sodium hypophosphite as the catalyst.(2)The melt crystallization behavior of nylon 12 with different molecular weights was studied by DSC.The results showed that the crystallinity of nylon 12 decreased with the increase of molecular weight,and the crystallization temperature increased gradually,which indicated that the increase of molecular weight was beneficial to the formation of crystal nuclei.(3)The thermal degradation of nylon 12 with different molecular weights was studied by TG.The results showed that the thermal degradation temperature of nylon 12 increased with the increase of molecular weight,and the thermal degradation process was completed by one step reaction,which conformed to the mechanism of random fracture.(4)The effects of different molecular weights nylon 12 on the processing technology and mechanical properties were studied,and the effects of water absorption and low temperature on physical and mechanical properties were studied.The results showed that with the increase of the molecular weight of nylon 12,the temperature and pressure required for the process increased gradually.After the absorption of nylon 12,the tensile strength and flexural strength decreased,the elongation at break and the notched impact strength increased;the tensile strength improved greatly at low temperature.(5)The relaxation of nylon 12 was studied by DMA.The results showed that there were two different relaxation changes in nylon 12,which were the α transition peak near 50℃ and the β transformation peak near-46℃.