聚乙烯支化結(jié)構(gòu)對無機填料在聚乙烯基體中分散性的影響
發(fā)布時間：2018-08-27 09:12
【摘要】：填料在復(fù)合材料中的分散情況很大程度上決定了復(fù)合材料成品的最終性能。本文選取兩種微觀結(jié)構(gòu)不同的無機填料(滑石粉、碳酸鈣)分別填充四種支化結(jié)構(gòu)存在較大差異的聚乙烯(HDPE、LDPE、LLDPE以及mPE)制備填充復(fù)合材料,通過動態(tài)流變測試以及SEM觀察等方法表征不同填料含量以及聚乙烯支化結(jié)構(gòu)的差異對填料粒子在復(fù)合體系中分散性的影響;通過DSC測試研究不同復(fù)合材料的熔融及結(jié)晶行為,并通過力學(xué)性能測試分析了在填料不同的分散情況對材料力學(xué)性能的影響。研究結(jié)果如下:研究結(jié)果表明:較高填充量滑石粉的加入對HDPE、LLDPE及mPE三種體系的動態(tài)流變行為有較大的影響,其在小應(yīng)變區(qū)域都呈現(xiàn)出明顯的Payne效應(yīng),儲能模量在低頻區(qū)對頻率變化十分敏感,表現(xiàn)出似固體行為,這表明三種高填充體系出現(xiàn)了滑石粉大量團(tuán)聚的現(xiàn)象;對于長支鏈結(jié)構(gòu)的LDPE復(fù)合體系,在小應(yīng)變區(qū)域都沒有出現(xiàn)Payne效應(yīng),低頻區(qū)域也沒有出現(xiàn)似固體行為,而剪切變稀行為在高頻區(qū)域則更加明顯。SEM觀察發(fā)現(xiàn),在HDPE、LLDPE及mPE三種基體中,滑石粉與基體間存在不同程度的空隙,滑石粉間的集聚現(xiàn)象較為明顯;對于LDPE/Talc體系,斷面十分光滑,沒有凸出的滑石粉粒子,兩相間沒有任何空隙。根據(jù)DSC數(shù)據(jù)分析,低填充體系中,滑石粉加入,體系的結(jié)晶度和結(jié)晶速率都有所提升;對于PE/Talc復(fù)合材料,滑石粉含量的提升,對復(fù)合體系的結(jié)晶速率都有提升。根據(jù)力學(xué)性能分析,低填充復(fù)合材料的力學(xué)性能都所提升;而在高填充體系,對HDPE、LLDPE及mPE三種復(fù)合材料,由于滑石粉間嚴(yán)重的團(tuán)聚行為,極大的降低了其力學(xué)性能。對于高填充LDPE/Talc復(fù)合材料中,其力學(xué)性能的損失相對較少。這得益于滑石粉在具有長支鏈結(jié)構(gòu)的LDPE基體中良好的分散性。PE/CaCO3復(fù)合材料流變行為與PE/Talc復(fù)合材料基本類似,但當(dāng)碳酸鈣填充量為30 vol%時,LDPE/CaCO3體系也出現(xiàn)了明顯的Payne效應(yīng)和似固體行為,其復(fù)合材料的力學(xué)性能也有較大的損失。這可能是由于碳酸鈣粒子更高的比表面積使得粒子間更易團(tuán)聚導(dǎo)致的。未使用偶聯(lián)劑改性填料填充體系的填料粒子存在更明顯的Payne效應(yīng),從SEM微觀形貌圖也可以看出其更容易發(fā)生團(tuán)聚行為,與基體的相容性也更差。
[Abstract]:The dispersion of fillers in the composites largely determines the final properties of the composites. In this paper, two inorganic fillers with different microstructure (talc powder and calcium carbonate) were used to prepare the filling composites, which were filled with polyethylene (HDPE,LDPE,LLDPE) and polyethylene (mPE) with different branched structure respectively. The effects of different filler content and polyethylene branching structure on the dispersion of filler particles in the composite system were characterized by means of dynamic rheological test and SEM observation, and the melting and crystallization behaviors of different composites were studied by DSC test. The effects of different dispersion of filler on mechanical properties of materials were analyzed by mechanical properties test. The results are as follows: the results show that the addition of high content talc powder has a great influence on the dynamic rheological behavior of HDPE,LLDPE and mPE systems, and the Payne effect is obvious in the small strain region. The energy storage modulus is very sensitive to the frequency change in the low frequency region, and shows solids like behavior, which indicates that the three kinds of high filling systems have the phenomenon of mass agglomeration of talcum powder, and for the LDPE composite system with long branched chain structure, the energy storage modulus is very sensitive to the frequency change in the low frequency region. There is no Payne effect in the small strain region, and no solids like behavior in the low frequency region, while the shear thinning behavior is more obvious in the high frequency region. It is found that in the three kinds of matrix, HDPE,LLDPE and mPE, the shear thinning behavior is more obvious. For the LDPE/Talc system, the section is very smooth, there is no protruding talc particles, and there is no void between the two phases. According to the analysis of DSC data, the crystallinity and crystallization rate of the low filling system increased with the addition of talcum powder, and the crystallization rate of the composite system increased with the increase of talcum powder content in the PE/Talc composite. According to the analysis of mechanical properties, the mechanical properties of low filling composites were all improved, while in high filling systems, the mechanical properties of HDPE,LLDPE and mPE composites were greatly reduced because of the serious agglomeration behavior between talc powder. For high filled LDPE/Talc composites, the loss of mechanical properties is relatively small. This is due to the good dispersion of talc powder in LDPE matrix with long branched structure. The rheological behavior of PE- / CaCO3 composites is similar to that of PE/Talc composites. However, when the content of calcium carbonate is 30 vol%, the Payne effect and solid-like behavior of LDPE / CaCO3 system are obvious, and the mechanical properties of the composites are also greatly lost. This may be due to the higher specific surface area of calcium carbonate particles, resulting in easier aggregation between particles. The Payne effect of the filler particles without coupling agent was more obvious, and the aggregation behavior and the compatibility with the matrix were also easy to occur from the SEM micrograph.
【學(xué)位授予單位】：湘潭大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：O632.12
本文編號：2206796
[Abstract]:The dispersion of fillers in the composites largely determines the final properties of the composites. In this paper, two inorganic fillers with different microstructure (talc powder and calcium carbonate) were used to prepare the filling composites, which were filled with polyethylene (HDPE,LDPE,LLDPE) and polyethylene (mPE) with different branched structure respectively. The effects of different filler content and polyethylene branching structure on the dispersion of filler particles in the composite system were characterized by means of dynamic rheological test and SEM observation, and the melting and crystallization behaviors of different composites were studied by DSC test. The effects of different dispersion of filler on mechanical properties of materials were analyzed by mechanical properties test. The results are as follows: the results show that the addition of high content talc powder has a great influence on the dynamic rheological behavior of HDPE,LLDPE and mPE systems, and the Payne effect is obvious in the small strain region. The energy storage modulus is very sensitive to the frequency change in the low frequency region, and shows solids like behavior, which indicates that the three kinds of high filling systems have the phenomenon of mass agglomeration of talcum powder, and for the LDPE composite system with long branched chain structure, the energy storage modulus is very sensitive to the frequency change in the low frequency region. There is no Payne effect in the small strain region, and no solids like behavior in the low frequency region, while the shear thinning behavior is more obvious in the high frequency region. It is found that in the three kinds of matrix, HDPE,LLDPE and mPE, the shear thinning behavior is more obvious. For the LDPE/Talc system, the section is very smooth, there is no protruding talc particles, and there is no void between the two phases. According to the analysis of DSC data, the crystallinity and crystallization rate of the low filling system increased with the addition of talcum powder, and the crystallization rate of the composite system increased with the increase of talcum powder content in the PE/Talc composite. According to the analysis of mechanical properties, the mechanical properties of low filling composites were all improved, while in high filling systems, the mechanical properties of HDPE,LLDPE and mPE composites were greatly reduced because of the serious agglomeration behavior between talc powder. For high filled LDPE/Talc composites, the loss of mechanical properties is relatively small. This is due to the good dispersion of talc powder in LDPE matrix with long branched structure. The rheological behavior of PE- / CaCO3 composites is similar to that of PE/Talc composites. However, when the content of calcium carbonate is 30 vol%, the Payne effect and solid-like behavior of LDPE / CaCO3 system are obvious, and the mechanical properties of the composites are also greatly lost. This may be due to the higher specific surface area of calcium carbonate particles, resulting in easier aggregation between particles. The Payne effect of the filler particles without coupling agent was more obvious, and the aggregation behavior and the compatibility with the matrix were also easy to occur from the SEM micrograph.
【學(xué)位授予單位】：湘潭大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：O632.12
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