钛酸钾晶须增韧尼龙66及其断面分形研究

FRACTAL RESEARCH OF FRACTURE SURFACES OF POTASSIUM TITANATE WHISKERS TOUGHENED NYLON 66

钛酸钾晶须用弹性体表面改性后实现了对尼龙 66的有效增韧。改性剂环氧树脂用量为晶须的1.5% (质量 )时 ,复合体系的冲击强度比纯尼龙 66提高 132 % ,同时弯曲、拉伸强度分别提高 55%和4 8%。采用显微图像灰度法 ,对晶须增韧尼龙进行了基于断面小岛周长 -面积关系的分形研究 ,考察了小岛选取对断面分维数测量结果的影响。研究表明 ,测得的分维数随选取小岛的面积阈值的增加而增大 ,面积阈值达 50 0 η2 ( η为测量码尺 )后 ,分维数趋于稳定。晶须增韧尼龙的力学强度与材料断面分维数之间的变化规律一致 。

Nylon 66 was effectively toughened with potassium titanate whiskers which were surface modified with an elastic epoxy resin. When the content of epoxy resin was of 1.5 mass% of whiskers, impact strength of the composite increased 132% compared with neat nylon, while bending and tensile strengths increased 55% and 48% respectively. Image gray level method was adopted to carry out fractal research of fracture surfaces of the composites. Fractal dimensional calculations were based on perimeter area relation. The influence of the sizes of measured slit islands on result fractal dimensions was discussed. It was found that with the area threshold of measured slit islands increasing, calculated fractal dimension increases first and becames stable after area threshold reaches about 500 η 2( η was yardstick). The relationships between mechanical properties of the composites and fractal dimensions of fracture surfaces were further examined. There was good consistence between mechanical properties and fractal dimension, which was explained from the fracture mechanism of composites and fracture morphology.