|
With the rapid development of science and technology, the automotive industry needs to be lightweight, electronic product miniaturization, precision and reduce the cost of cables and wires need more weathering. Therefore, the organic materials used in heat resistance, precision moldability, and dimensional stability of the more stringent requirements. Polyamides have a wide range of applications in various fields, the polyamide fibers continue to research and development, and plays an important role in electronic communications, cars, clothing, and other industries. In order to adapt to the new requirements of its heat resistance, water absorption, dimensional stability, etc., when people during molecular structure design introduced in the molecular main chain with a thermal stability, good aromatic ring with an aromatic acid or amine in place of the aliphatic acid or amine, to synthesize a semi-aromatic polyamide, the advantages of both the aromatic and aliphatic polyamides such new polyamide, has become one of the hotspot. By selecting a suitable semi-aromatic polyamide materials and their thermal degradation mechanism and non-isothermal crystallization kinetics analysis, to provide a reference for the spinning process parameters selection. Through a twin screw extruder, to adjust appropriate process parameters, a semi-aromatic polyamide was prepared nascent fiber, and using the heat treatment of the fiber subsequent processing. The results showed that: 1, through the melt index (MI), DSC, TG test results compare, select a melt index 17.72g/min, a melting point of 290 ° C, thermal decomposition temperature above 450 ℃ semi-aromatic polyamide as a spinning raw materials. 2, semi-aromatic polyamide thermal degradation process step reaction, semi-aromatic polyamide thermal degradation kinetics of the sample can be analyzed using the Kissinger method and Flynn-Wall-Ozawa method, calculated semi-aromatic polyamides obtained by the two methods sample thermal decomposition activation energy 258.37kJ/mol and 227.41 kJ / mol. And analysis of the degradation of the two possible mechanisms. 3, DSC nonisothermal crystallization process and its dynamics of semi-aromatic polyamide. A crystallization peak of the trend is to move towards low, and the width of the crystallization peak widens with increasing cooling rate that the cooling crystallization process by nucleation control. The semi-crystallization period t1 / 2 is decreased with the increase of the cooling rate. Under non-isothermal conditions may be in accordance with the semi-aromatic polyamide crystalline lamellae form of growth, as the cooling rate increases, into a three-dimensional spherulite growth. 3, through a twin screw extruder of a semi-aromatic polyamide pellets spinning process, the slow cooling means of the increase of a length of 40cm below the spinneret, the melt difficult problem into fiber can solve slow cooling means controlling the temperature at about 220 ℃. Spinning temperature between 295-320 ℃, the mechanical properties of the fiber test found protofibers already have a certain mechanical properties. The semi-aromatic polyamide fiber is subjected to a heat treatment, and found that its elongation at break is greatly decreased, the strength and modulus is greatly increased, indicates that the latter process can improve the mechanical properties of the semi-aromatic polyamide fibers. 160 ° C, 60min heat treatment conditions is more appropriate considering the impact of heat treatment on the thermal and mechanical properties of the semi-aromatic polyamide, and ultimately obtained a melting point of about 300 ° C, the elongation at break of about 6% of the initial modulus and The tensile strength of about 12.3GPa and 0.77GPa, comprehensive performance is much improved semi-aromatic polyamide fibers.
|