退火对PA6结晶和拉伸性能的影响

通过调节退火时间和退火温度,研究了退火工艺对尼龙(PA)6结晶性能以及PA6在不同拉伸速率下的拉伸性能的影响。结果表明,在100℃恒温退火时,随着退火时间的增加,PA6初始熔融温度逐渐升高,熔限减小,γ晶的晶粒尺寸增大,但结晶度变化不大;在5 h退火时间下,随着退火温度的增加,PA6结晶度呈现先增加后降低的趋势,而α晶晶粒尺寸逐渐增大。总体上看,不同拉伸速率下退火时间和退火温度对拉伸强度的影响较小,相对来看,退火温度为100℃时拉伸强度较高,而当退火温度达到200℃时,拉伸强度显著下降;当拉伸速率较高或较低时,不同退火时间下的PA6断裂伸长率相差不大,而当拉伸速率为20,50 mm/min时,随退火时间的增加,断裂伸长率逐渐降低;退火温度为100,130℃的PA6断裂伸长率保持在相对较高值,且拉伸速率越低,其值越高,但随着拉伸速率增加,其下降趋势也最快;高拉伸速率下,退火温度对PA6断裂伸长率影响较小。以上结果表明,当对PA6进行退火处理时,在拉伸性能方面需要考虑拉伸速率的影响。

Effect of Annealing on Crystallinity and Tensile Properties of PA6

By adjusting the annealing time and annealing temperature,the influences of annealing process on crystallinity performances and tensile properties under different tensile rates of nylon (PA) 6 were researched. The results show that when PA6 is treated by constant temperature annealing at 100℃,with the growth of annealing time,the initial melting temperature of PA6 in-creases gradually,melting limit minishes,grain size ofγ-form crystal increases,while the degree of crystallinity of PA6 changes much little. Meanwhile,with the increase of annealing temperature when annealing time is 5 h,the degree of crystallinity of PA6 presents the trend of the first increase and then decrease,grain size ofα-form gets large gradually. Overall,the effect of annealing time and annealing temperature under the different tensile rates on tensile properties of PA6 is slight. But comparatively speaking, when the annealing temperature is 100℃,the tensile strength reaches a higher value,when temperature amounts to 200℃,the ten-sile strength of PA6 declines sharply. In addition,when the tensile rate is higher or lower,the difference value of elongation at break of PA6 under the different annealing time is smaller,but when the tensile rate is 20,50 mm/min,the elongation at break declines gradually with the growth of annealing time. The elongation at break of PA6 remains a relative higher value when annealing tempera-ture is 100,130℃and the lower the tensile rate is,the higher the value is,however,the value decline trend is the fastest with the increase of the tensile rate. Under high tensile rate,annealing temperature has less impact on elongation at break of PA6. The results mentioned above indicate that when treating PA6 by annealing,the effects of the tensile rate need to be considered in the aspect of its tensile properties.