聚苯乙烯論文碳納米管選擇性分散及其誘導(dǎo)不相容共混物結(jié)晶的研究

1、聚苯乙烯論文：碳納米管選擇性分散及其誘導(dǎo)不相容共混物結(jié)晶的研究【中文摘要】聚合物共混改性可以使單一聚合物的性能優(yōu)化組合,并且獲得一些特殊性能,成為開發(fā)新型高分子材料的有效途徑。對于大部分的聚合物在熱力學(xué)上是不相容的,不相容共混物增容改性的方法很多,添加無機(jī)納米填料是一種實(shí)際有效的方法。碳納米管(Carbon Nanotubes, CNTs)自從被發(fā)現(xiàn)以來,由于其具有優(yōu)異的力學(xué)、導(dǎo)電、導(dǎo)熱特性而備受關(guān)注,此外碳納米管對結(jié)晶聚合物是很好的成核劑,少量的碳納米管可以誘導(dǎo)結(jié)晶,降低結(jié)晶活化能,提高結(jié)晶速率。聚苯乙烯(Polystyrene, PS).聚丙烯(Polypropylene, PP)、聚對苯

2、二甲酸乙二醇酯(Polyethylene terephthalate, PET)在生活、工程應(yīng)用上很廣泛,對其進(jìn)行共混改性具有現(xiàn)實(shí)意義。本論文以PS/PP、PS/PET不相容共混物作為研究對象,多壁碳納米管(Multi-Walled Nanotubes, MWCNTs)做為無機(jī)納米填料來制備納米復(fù)合材料。首先對碳納米管進(jìn)行化學(xué)改性,改善其與基體之間的相互作用,控制其在復(fù)合材料中的分布；研究了加工共混條件、增容劑的添加、界面條件等對碳納米管在不相容共混物中選擇性分布的影響,并進(jìn)一步探討了碳納米管的分布對結(jié)晶相的結(jié)晶行為以及對復(fù)合材料微觀相形貌的影響。主要研究結(jié)果如下：(1)對碳納米管先酸化處理,

3、然后與馬來酸酐反應(yīng),使其表面接枝上羰基、羥基、羧基等活性基團(tuán),得到改性的多壁碳納米管(Functionalized Multi-walled Carbon Nanotubes, F-MWCNTs)。(2)把F-MWCNTs加入到PS/PP不相容共混物中,PS與F-MWCNTs通過溶液法配制母料,再與其他組分?jǐn)D出注塑制備復(fù)合材料。對PP結(jié)晶行為的研究發(fā)現(xiàn),PS/PP共混物中,PP在低溫、高溫處出現(xiàn)兩個(gè)結(jié)晶峰,有分級結(jié)晶現(xiàn)象,但添加F-MWCNTs后PP只有一個(gè)高溫結(jié)晶峰,分級結(jié)晶現(xiàn)象消失；同時(shí),PS/PP/F-MWCNTs復(fù)合材料中PP相的結(jié)晶溫度比PS/PP共混物中PP相的結(jié)晶溫度高,復(fù)合材料

4、中PP相的結(jié)晶溫度隨著PP含量的增加而逐漸提高,表明F-MWCNTs跟PP間相互作用更強(qiáng),F-MWCNTs從PS相遷移到了PP相中,F-MWCNTs作為很好的異相成核劑誘導(dǎo)PP結(jié)晶。另外動態(tài)力學(xué)分析(Dynamic Mechanical Analysis, DMA)數(shù)據(jù)表明,復(fù)合材料中PS、PP的玻璃化溫度有所降低,說明F-MWCNTs充當(dāng)了增塑劑的作用。掃描電子顯微鏡(Scanning Electron Microscope, SEM)對復(fù)合材料相形貌研究表明F-MWCNTs的引入在一定程度上促進(jìn)了PS/PP相形貌從“海島”相向雙連續(xù)相的轉(zhuǎn)變。(3)在80PP/20PS不相容共混物中添加馬來

5、酸酐接枝苯乙烯-乙烯-丁二烯-苯乙烯(Maleic Anhydride Grafted Styrene-Ethylene-Butylenes-Styrene, SEBS-MA)作為增容劑,降低了兩相的界面張力,增強(qiáng)了兩相間的粘結(jié)力,分散相粒徑變小,分散更均勻。同時(shí)研究了加工共混條件以及增容劑對F-MWCNTs在復(fù)合材料中選擇性分布情況的影響。以PP/F-MWCNTs作為母料制備的納米復(fù)合材料,SEBS-MA加入后PP的結(jié)晶溫度降低,表明F-MWCNTs與SEBS-MA的相互作用比較強(qiáng),部分的F-MWCNTs被SEBS-MA誘導(dǎo)而從PP相中遷移出來；DMA表征發(fā)現(xiàn)PS玻璃化溫度沒有變化,F-MW

6、CNTs并沒有遷移到PS相中。以PS/F-MWCNTs作為母料制備的納米復(fù)合材料,各個(gè)組分中PP的結(jié)晶溫度變化不大,DMA結(jié)果發(fā)現(xiàn)PP玻璃化溫度也沒有變化,說明F-MWCNTs沒有遷移到PP相中,主要還是分布在PS相中,SEBS-MA的存在可以阻止F-MWCNTs的遷移。以PP-MA為基體,PS/F-MWCNTs為母料制備的納米復(fù)合材料,PP-MA結(jié)晶行為的研究也說明SEBS-MA與F-MWCNTs之間的相互作用力比PP-MA與F-MWCNTs之間的作用力更強(qiáng)。(4)制備了PS/PET/F-MWCNTs納米復(fù)合材料,通過熱力學(xué)潤濕系數(shù)計(jì)算表明F-MWCNTs傾向于分布在PET相中。對復(fù)合材料中

7、PET的結(jié)晶行為的研究表明F-MWCNTs誘導(dǎo)PET結(jié)晶,起到了很好的異相成核作用,F-MWCNTs從PS相往PET相遷移；通過SEM直觀的反映了F-MWCNTs主要分布在PET相中及兩相界面,驗(yàn)證了F-MWCNTs在復(fù)合材料中的分布情況。【英文摘要】Polymer blending is a convenient and efficient route for the development of new polymeric materials, which can combine the excellent and special properties of the constituent

8、 polymers. Many polymer blends are immiscible and their blends exhibit poor mechanical properties. Among various techniques used to compatibilize polymer blends, adding inorganic nanofillers is proved to be one of the most efficient methods. Since their discovery, carbon nanotubes (CNTs) attracted t

9、remendous attention due to their superior mechanical, electrical and thermal properties. CNTs have been proved to be a good nucleating agent for crystallization of polymers. The addition of a few CNTs in semicrystalline polymer can efficiently promote the crystallization by decreasing the nucleation

10、 activation energy and accelerating crystallization rate. Polystyrene (PS), polypropylene (PP) and polyethylene terephthalate (PET) are important engineering polymers used in a wide variety of applications, and melt blending of them are of practical significance. In this research, nanocomposites of

11、PS/PP and PS/PET containing Multi-walled nanotubes (MWCNTs) were mainly prepared by direct melt blending. MWCNTs were firstly functionalized to improve the adhesion with polymer matrices, so we can control the localization and dispersion of MWCNTs in immiscible polymer blends. The selective localiza

12、tion of MWCNTs in nanocomposites was realized by the different blending sequences, the use of compatibilizer, etc. Furthermore, the effect of selective localization of MWCNTs on the crystallization and morphology behaviors of nanocomposites were discussed. The main results obtained in this work are

13、listed as follows:(1)The pristine carbon nanotubes were first acidified in nitric acid and then reacted with maleic acid, to introduce carbonyl, carboxyl and hydroxide groups onto the surface of carbon nanotubes and the final products are called Functionalized multi-walled carbon nanotubes (F-MWCNTs

14、).(2)PS/PP blends containing F-MWCNTs were prepared using a twin screw extruder followed by injection molding, the F-MWCNTs was firstly dispersed in solvent to obtain PS/F-MWCNTs master batch and then the master batch was melt blended with different contents of PP and PS to obtain samples with corre

15、sponding compositions. For the PS/PP blends without F-MWCNTs, two exothermic peaks were presented in the cooling curve of PP phase, indicating fractionated crystallization of PP. The PS/PP/F-MWCNTs nannocomposites exhibited only one exothermic peak indicating that only bulk crystallization of PP pha

16、se occurred during the cooling process. Furthermore, the nanocomposite exhibited higher crystallization temperature compared with the corresponding blends without F-MWCNTs, and the crystallization temperature shifted to higher temperatures at higher content of PP. It proved that F-MWCNTs migrated fr

17、om the PS phase to the PP phase, and nucleated the crystallization of PP. The DMA results showed that F-MWCNTs exhibited as a plasticizer for both PS and PP, decreasing the glass-transition temperature of both PP and PS in PS/PP/F-MWCNTs nanocomposites. SEM results showed that the presence of F-MWCN

18、Ts induced the morphology of the immiscible blends to change from sea-island morphology to co-continuous morphology to a certain degree.(3)Addition of maleic anhydride grafted styrene-ethylene-butylenes-styrene (SEBS-MA) as compatibilizer to 80PP/20PS blends can compatibilize the blends by reducing

19、the interfacial tension and enhancing the interfacial adhesion, and consequently result in smaller dispersed particles with better distribution. The different blending sequences and usage of compatibilizer on the selective localization of F-MWCNTs was discussed. When the F-MWCNTs were first disperse

20、d in PP and then blended with other components, the crystallization temperature of PP phase shifted to lower temperature when SEBS-MA are added, indicating the migration of F-MWCNTs to the SEBS-MA, which characterized high affinity. Due to the migration of F-MWCNTs into the SEBS-MA, less F-MWCNTs re

21、mained in the PP phase, leading to decreased temperature of PP phase. The DMA results showed that glass-transition behaviors of PS had not changed, meaning that F-MWCNTs remained on the interface instead of migrating into the PS phase. When the F-MWCNTs were first dispersed in PS and then blended wi

22、th other components to prepared the nanocomposites, the crystallization temperature of PP in different composites are nearly the same, and the DMA results showed that glass-transition behaviors of PP had not changed, indicating that the F-MWCNTs stayed in the PS phase due to obstruction of F-MWCNTs

23、imposed by the SEBS-MA. For the 80PP-MA/20PS/SEBS-MA/F-MWCNTs nanocomposites with PS master batch, the crystallization behavior of PP-MA showed that F-MWCNTs had better affinity with SEBS-MA than PP-MA in 80PP-MA/20PS/SEBS-MA/F-MWCNTs nanocomposite.(4)The PS/PET/F-MWCNTs nanocomposites were prepared

24、, and the wetting coefficients predicted that the F-MWCNTs should selective localized in PET. And the DSC test showed that F-MWCNTs exhibited obvious nucleating effect for the crystallization of PET. So, for PS/PET/F-MWCNTs nanocomposites, F-MWCNTs have higher affinity with the PET phase, it could m

25、igrate from the PS phase to the PET phase. The SEM observations showed that the localization of the F-MWCNTs at the interface and in PET phase, and the experimental results confirmed the results of prediction.【關(guān)鍵詞】聚苯乙烯 聚丙烯 聚對苯二甲酸乙二醇酯 碳納米管 馬來酸酐接枝苯乙烯-乙烯-丁二烯-苯乙烯 選擇性分散 結(jié)晶【英文關(guān)鍵詞】Polystyrene Polypropylene

26、 Polyethylene terephthalate Carbon nanotubes Maleic anhydride grafted Styrene-ethylene-butylenes-styrene Selective localization Crystallization【目錄】碳納米管選擇性分散及其誘導(dǎo)不相容共混物結(jié)晶的研究摘要7-9Abstract9-11第1章 緒論14-411.1 聚合物共混物的形態(tài)結(jié)構(gòu)15-171.1.1 非結(jié)晶聚合物/非結(jié)晶聚合物體系15-161.1.2 結(jié)晶聚合物/非結(jié)晶聚合物體系161.1.3 結(jié)晶聚合物/結(jié)晶聚合物體系16-171.2 不相容共混物結(jié)晶的研究17-261.2.1 高分子材料結(jié)晶理論17-201.2.2 分級結(jié)晶20-231.2.3 受限結(jié)晶23-241.2.4 共混物組分相互影響結(jié)晶24-261.3 調(diào)控不相容共混物結(jié)晶的方法26-301.3.1 成核劑26-271.3.2 增容劑27-281.3.3 熱處理28-291.3.4 加工條件29-301.4 無機(jī)納米粒子改性不相容共混物研究進(jìn)展30-361.4.1 無機(jī)納米粒子對不相容共混物的增容作用30-321.4.2 無機(jī)納米粒子在不相容共混物中選擇性分散與遷移32-361.5 碳納米管/聚合物復(fù)合