【摘要】：無(wú)機(jī)粒子填充改性是聚合物基新材料開(kāi)發(fā)的重要手段,填充改性后的復(fù)合材料能否達(dá)到預(yù)期效果主要受到填充粒子的分散狀況的影響,因此對(duì)填充粒子在復(fù)合材料中的分散狀態(tài)的測(cè)量表征十分重要。超聲波測(cè)量信號(hào)對(duì)材料內(nèi)部微觀結(jié)構(gòu)十分敏感,另外超聲波具有無(wú)損,實(shí)時(shí)等特點(diǎn),非常適合于對(duì)粒子填充復(fù)合材料的表征。通過(guò)研究超聲波檢測(cè)信號(hào)與填充粒子分散狀態(tài)的量化關(guān)系,優(yōu)化改進(jìn)適用的表征模型,拓展超聲波檢測(cè)技術(shù)在聚合物填充改性材料中的應(yīng)用,形成一種快捷、方便表征填充粒子分散狀況的方法,具有重大的實(shí)際應(yīng)用價(jià)值和顯著的科學(xué)意義。相比聲速而言,超聲波測(cè)量中得到衰減系數(shù)與填充體系微觀結(jié)構(gòu)的關(guān)系更為顯著。本文在對(duì)比了不同描述超聲波在復(fù)合體系中傳播所產(chǎn)生衰減的理論模型后,選擇微分模型作為研究對(duì)象,進(jìn)行了實(shí)驗(yàn)驗(yàn)證研究。通過(guò)改變加入聚合物基體中填充粒子的體積分?jǐn)?shù)(6%、10%、20%、30%、40%、50%)、粒徑大小(70μm、160μm)及分布狀況(單峰分布、雙峰分布)等方面因素,獲得內(nèi)部有著不同分散狀態(tài)的復(fù)合材料樣品。本文采用超聲波脈沖回波法對(duì)樣品進(jìn)行超聲波檢測(cè),用頻譜分析方法對(duì)不同頻率下的不同樣品的聲學(xué)衰減系數(shù)進(jìn)行分析,得到不同頻率下的聲衰減系數(shù),并將實(shí)驗(yàn)測(cè)得的結(jié)果與微分模型計(jì)算值進(jìn)行對(duì)比,驗(yàn)證其模型適用范圍。研究表明:(1)對(duì)于粒徑呈單峰分布的粒子填充復(fù)合材料,粒子的粒徑越大,其聲衰減系數(shù)越大,而聲速越小;隨著體積分?jǐn)?shù)的增加其聲衰減系數(shù)先增加后減小,而聲速增加。將實(shí)驗(yàn)測(cè)得的聲衰減系數(shù)與微分模型進(jìn)行對(duì)比,填料體積分?jǐn)?shù)達(dá)50%時(shí)兩者的結(jié)果仍然較為吻合,證明了微分模型適用于不同含量、不同粒徑粒子填充的復(fù)合材料。(2)對(duì)于粒徑呈雙峰分布的粒子填充復(fù)合材料,粒子體積分?jǐn)?shù)相同時(shí),粒徑大的粒子所占比例越高其聲衰減系數(shù)越大,而聲速越小;粒子粒徑分布相同時(shí),隨著體積分?jǐn)?shù)增加其聲衰減系數(shù)先增加后減小,而聲速增加。通過(guò)對(duì)微分模型進(jìn)行修正,其聲衰減系數(shù)可以看作兩個(gè)組分的聲衰減系數(shù)的線性加和,并與實(shí)驗(yàn)值進(jìn)行對(duì)比,填料體積分?jǐn)?shù)達(dá)30%時(shí)兩者結(jié)果仍然較為吻合,證明了修正后的微分模型適用于粒徑呈雙峰分布的粒子高填充復(fù)合材料,擴(kuò)大了原有模型的適用范圍。
[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.
【學(xué)位授予單位】：華南理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TB33

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