基于超声信号的无机粒子高填充聚合物分散状态表征研究

发布时间：2018-12-30 19:42

【摘要】：无机粒子填充改性是聚合物基新材料开发的重要手段,填充改性后的复合材料能否达到预期效果主要受到填充粒子的分散状况的影响,因此对填充粒子在复合材料中的分散状态的测量表征十分重要。超声波测量信号对材料内部微观结构十分敏感,另外超声波具有无损,实时等特点,非常适合于对粒子填充复合材料的表征。通过研究超声波检测信号与填充粒子分散状态的量化关系,优化改进适用的表征模型,拓展超声波检测技术在聚合物填充改性材料中的应用,形成一种快捷、方便表征填充粒子分散状况的方法,具有重大的实际应用价值和显著的科学意义。相比声速而言,超声波测量中得到衰减系数与填充体系微观结构的关系更为显著。本文在对比了不同描述超声波在复合体系中传播所产生衰减的理论模型后,选择微分模型作为研究对象,进行了实验验证研究。通过改变加入聚合物基体中填充粒子的体积分数(6%、10%、20%、30%、40%、50%)、粒径大小(70μm、160μm)及分布状况(单峰分布、双峰分布)等方面因素,获得内部有着不同分散状态的复合材料样品。本文采用超声波脉冲回波法对样品进行超声波检测,用频谱分析方法对不同频率下的不同样品的声学衰减系数进行分析,得到不同频率下的声衰减系数,并将实验测得的结果与微分模型计算值进行对比,验证其模型适用范围。研究表明:(1)对于粒径呈单峰分布的粒子填充复合材料,粒子的粒径越大,其声衰减系数越大,而声速越小;随着体积分数的增加其声衰减系数先增加后减小,而声速增加。将实验测得的声衰减系数与微分模型进行对比,填料体积分数达50%时两者的结果仍然较为吻合,证明了微分模型适用于不同含量、不同粒径粒子填充的复合材料。(2)对于粒径呈双峰分布的粒子填充复合材料,粒子体积分数相同时,粒径大的粒子所占比例越高其声衰减系数越大,而声速越小;粒子粒径分布相同时,随着体积分数增加其声衰减系数先增加后减小,而声速增加。通过对微分模型进行修正,其声衰减系数可以看作两个组分的声衰减系数的线性加和,并与实验值进行对比,填料体积分数达30%时两者结果仍然较为吻合,证明了修正后的微分模型适用于粒径呈双峰分布的粒子高填充复合材料,扩大了原有模型的适用范围。
[Abstract]:Inorganic particle filling modification is an important method for the development of new polymer-based materials. Whether the modified composites can achieve the desired results is mainly affected by the dispersion of the filled particles. Therefore, it is very important to measure and characterize the dispersed state of filled particles in composites. The ultrasonic measurement signal is sensitive to the microstructure of the material. In addition, the ultrasonic wave has the characteristics of nondestructive and real-time, so it is very suitable for the characterization of particle filled composites. By studying the quantitative relationship between ultrasonic testing signal and dispersed state of filled particles, optimizing and improving the suitable characterization model, expanding the application of ultrasonic detection technology in polymer filled modified materials, forming a kind of fast, It is of great practical value and scientific significance to characterize the dispersion of filled particles. Compared with the velocity of sound, the relationship between the attenuation coefficient and the microstructure of the filled system is more significant. After comparing the different theoretical models describing the attenuation of ultrasonic wave propagation in the composite system, the differential model is selected as the object of study, and the experimental verification is carried out. By changing the volume fraction of the particles filled in the polymer matrix (610%), the particle size (70 渭 m 160 渭 m) and the distribution (single peak distribution, double peak distribution), etc., Composite samples with different dispersion states were obtained. In this paper, ultrasonic wave echo method is used to detect the samples. The acoustic attenuation coefficient of different samples at different frequencies is analyzed by spectrum analysis method, and the acoustic attenuation coefficients at different frequencies are obtained. The experimental results are compared with the calculated values of the differential model to verify the applicability of the model. The results show that: (1) the larger the particle size, the larger the sound attenuation coefficient and the smaller the sound velocity for the particle filled composites with single peak particle size distribution; With the increase of volume fraction, the sound attenuation coefficient first increases and then decreases, while the sound velocity increases. Comparing the experimental acoustic attenuation coefficient with the differential model, the results of the two models are still in good agreement with each other when the packing volume fraction reaches 50. It is proved that the differential model is suitable for different contents. (2) for the composite with bimodal particle size distribution, the larger the particle volume fraction is, the higher the sound attenuation coefficient is and the smaller the sound velocity is. When the particle size distribution is the same, the sound attenuation coefficient increases first and then decreases with the increase of volume fraction, while the sound velocity increases. By modifying the differential model, the acoustic attenuation coefficient can be regarded as the linear sum of the sound attenuation coefficients of the two components, and compared with the experimental results, the results are still in good agreement with each other when the packing volume fraction reaches 30%. It is proved that the modified differential model is suitable for high filling composites with bimodal particle size distribution, which extends the scope of application of the original model.
【学位授予单位】：华南理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB33

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