关键词: 聚酰胺6, 三聚氰胺氰尿酸, 阻燃改性, 动态流变

Abstract: Polyamide 6 (PA6) is a polymer with excellent properties, and is widely used in the field of the textile industry due to its excellent abrasion and fatigue resistance as well as excellent elastic recovery rate, but it is a flammable product and also produces flaming molten droplets during combustion, which is highly susceptible to fire hazard. At present, research on flame-retardant PA6 focuses on plastic products, while research on fiber products is less. 
Rheological performance is an important index for evaluating the spinnability of materials. To investigate the spinnability of flame-retardant PA6, a twin-screw extruder was used to co-extrude 2%, 5% and 8% of flame-retardant PA6 with PA6 and flame retardant melamine cyanurate (MCA) as the raw materials. The melt crystallinity, thermal stability and rheological properties of the specimens were studied by a scanning calorimeter, a thermogravimetric analyzer and a rotational rheometer, and the effects of different frequency scans, MCA addition ratios and temperatures on the polymer properties were analyzed. The results show that MCA makes the flame-retardant PA6 have higher crystallization temperature, and the crystallinity increases and then decreases with the addition of MCA, which indicates that the low addition ratio of MCA can promote the crystallization behavior of PA6, while the high ratio of MCA will hinder the crystallization of PA6; the maximum decomposition rate of the flame-retardant PA6 decreases with the increase of the ratio of MCA, there is no much difference in T5% and T50%, and the residual carbon rates are not much different, which indicates that MCA reduces the thermal decomposition rate of PA6, and improve its thermal stability, but does not affect the residual carbon. To ensure the performance of the material, it is recommended that the processing temperature is selected below 300℃; the addition of MCA has a greater impact on the rheological properties of the material, flame-retardant PA6 is a pseudo-plastic fluid with shear thinning phenomenon. The larger the amount of MCA added, the greater the viscosity of the material. The addition of 8% can double the viscosity of the material, resulting in  poor melt fluidity, which is not conducive to subsequent spinning. However, the addition of MCA also makes the material rigidity and strength better. The higher the temperature, the lower the viscosity of the material. And when the temperature reaches 275℃, the viscosity will be too small for spinning. 
The results of the study are of theoretical significance for the practical production of MCA flame-retardant and modified PA6 fibers.

Key words: PA6, MCA, flame-retardant and modified, dynamic rheology