用户名: 密码: 验证码:
熔融插层聚乙烯—蒙脱土纳米复合材料形态结构及流变行为
详细信息    本馆镜像全文|  推荐本文 |  |   获取CNKI官网全文
摘要
采用两步法熔融插层工艺,在双螺杆挤出机上制备了以乙烯—醋酸乙烯共聚物(EVA)为增容剂的低密度聚乙烯(LDPE)基蒙脱土纳米复合材料。通过X-衍射(XRD)、热重分析(TG)、透射电子显微镜(TEM)、扫描电子显微镜(SEM)以及傅立叶变换红外光谱(FT-IR)的表征结果讨论了影响蒙脱土剥离的因素,分析了复合材料的形态结构和性能。用高级流变扩展系统(ARES)及毛细管流变仪对复合体系熔体的线性粘弹行为、稳态剪切流变行为进行了表征,并对熔体粒子网络结构的形成与演化作了较系统的研究。
     研究发现,非极性聚合物LDPE很难插层于无机蒙脱土片层间,即使用烷基季铵盐类的有机插层处理剂对蒙脱土进行有机化处理后,也较难与LDPE作用而良好剥离分散于基体中。而加入EVA作为增容剂后,聚合物分子易于插层。
     复合材料的制备受多种因素的影响,其中蒙脱土结构的不稳定性不容忽视。由于在高热(200℃以上)或强机械剪切作用下,蒙脱土层状堆叠结构会坍塌,导致不能与聚合物分子作用生成聚合物—层状硅酸盐纳米复合材料,因此熔融插层的温度选择显得十分重要。另一方面,EVA与LDPE的配比、添加方式等因素,均对复合材料中蒙脱土的最终分散状况造成影响。实验结果表明,LDPE/EVA=77/20是一比较理想的配比,可以兼顾插层效果和工艺的可行。在该配比下,可通过双螺杆挤出机,先将EVA与有机蒙脱土熔融挤出复合后,再与LDPE熔融挤出复合,制备具有剥离结构的LDPE基蒙脱土纳米复合材料。
     TEM、FT-IR等表征发现,复合材料中蒙脱土片层可以很好地剥离分散于聚合物基体中,但片层并非完全以单片层分散状态剥离,而是以片层堆叠形成“准粒子”;同时,还存在一定量的团聚体。蒙脱土片层之间、蒙脱土片层与聚合物基体间均具有强烈的相互作用。由于片层在基体中不呈单片层分散状,故复合材
    
    浙江大学博上学位论文
    摘要
    料的拉伸模量大大低于由加加动一Tsa艺连续方程得到理论计算值。尽管如此,复
    氛菜馨摹氰摆默氢篡资鼎迄饭琴氰黔耀零髯
    的特殊性能均得益于由径厚比较大的蒙脱土片层在基体中良好的分散。
     复合材料熔体呈现独特的线性粘弹行为。在蒙脱土含量低至3叭%时,体系
    低频率区域(末端区域)的动态模量出现近似于固体的粘弹行为尸类固
    (s olid-li毅的”行为),模量对频率依赖性降低甚至无依赖性。然而当蒙脱土含量低
    于和脸或蒙脱土片层在基体中呈完全团聚状态,则复合材料表现出与聚合物
    基体类似的线性粘弹特性。实验发现,在熔体经大振幅振荡剪切后,上述“类固..
    行为会明显减弱。表明良好剥离分散的蒙脱土片层在聚合物基体中由于强烈相互
     子网络结构是其独特粘弹行为的关键。研究结果表明仁复合体系
     G‘和动态损耗模量宁的对数关系性呀G‘一109夕,_印维乖温
     动态模量满足时温叠加原理,频率移动因子(aT)的对数与塌度
    的倒攀即种马与了一‘有良好的线性关系·一_
     面,复合体系熔体的稳态剪切流变行为具有不同于普通粒子填充聚合
     性。在低剪切速率下,复合体系熔体仍存在牛顿流动区。同时可观察
    到填充舞合物体系特有的屈服和剪切变稀现象·与普通粒子填充聚合物体系相
    比,耳9辉基蒙脱土纳米复合体系在相对较低的填充量时剪切变稀即十分明显宁
     黑翼器钾纂器纂粱鬓攀鬓耀馨鬓告片
    。粼翼踪艾需囊簇是翼暴攀黯黯纂袅
    作用的存在,是该体系结构一性能关系的根源。___
The nanocomposites with exfoliated structure composed of low density polyethylene (LDPE), of organically modified montmorillonite and ethylene vinyl acetate copolymer (EVA) were prepared through two steps melt intercalating technique using a twin-screw extruder. The factors relevant to montmorillonite intercalation and exfoliation were analyzed through X-ray diffraction (XRD), thermogravimetry (TG), transmission electron microscope (TEM), scanning electron microscope (SEM) and Fourier transform infraredspectroscopy (FT-IR). The morphology, structure and properties for the composites were discussed. And the linear viscoelastic behavior, steady rheological behavior and the formation/evolvement of particles net structure for molten nanocomposites were studied using an advanced rheometric expansion system (ARES) and capillary rheometry.
    It is believed that the melt intercalation is a more efficient processing for formation of nanophase in polymer-layered silicates hybrids. LDPE intercalated into the space between the layers of organically modified montmorillonite (org-MMT), especially in the presence of compatibilizer EVA. The unstable stacking of layers of org-MMT was easily damaged under force and heat. Hence, it is very important to decide the process temperature for preparing the composites, and it was found that 200 ℃ was a upper limitation of temperature. On the other hand, the proportion of LDPE/EVA and adding of EVA were very important factors for composites preparing. The results shown that the nanocomposites with exfoliated structure could be prepared in the case of LDPE/EVA=77/20, EVA/org-MMT melted firstly and then extruded with LDPE using a twin-screw extruder.
    
    
    The layers of montmorillonite could disperse into polymer matrix uniformly rather than individually. Based on TEM images and FT-IR characteristics, it is found that most of layers formed as "pseudoparticles", which connected due to very strong
    interaction. As a result, the tensile modulus of the composites were more tower than the corresponding values calculated by using Halpin-Tsai continuous equation, but higher than those of polymer matrix. While the steam barrier of films prepared by casting from the composites were enhanced as compared with that of the matrix film.
    The linear viscoelastic behavior of melts for nanocomposites with different content of montmorillonite modified by cetyltrimethylammonium bromide and octadecyltrimethylammonium bromide was studied. The results obtained through examining the dynamic storage module G', dynamic loss module G" and stress relaxtion module G(t) of the composites revealed that the linear viscoelastic properties of composites strongly depended on the loadings of montmorillonite exfoliated into the composites. With the increasing of montmorillonite content ,the
    composites showed a trend of pseudo-solidlike at lower frequencies, The montmorillonite layers could align along the stress direction, and as a result, the dependence of dynamic modules on the frequency was quite different before and after suffering from large amplitude oscillatory shear.
    The results obtained through examining loss tangent tan at deferent temperature and G' dependence on frequency ω of the composites revealed that the secondary
    relaxation asd G' of samples depended on the loadings of montmorillonite exfoliated into the composites. With the increasing of montmorillonite loading, the peak position corresponding to secondary relaxation for composites moved to higher and the peak values appeard higher, too. Time-temperature superposition principle could bee applied to G' dependence on CD, and the dependence of shifted factor aT on temperature demonstrated a linear relationship by a plot of In aT vs. T-1.
    The steady rheological measurements for nanocomposites melts were conducted.
    The results revealed that the melts of exfoliated nanocomposites with lower loading of
    org-MMT exhibited shear-thinning even at lower shear rate as compared with polymers filled with common particles, while the melts flow depended weakl
引文
1 R.Roy, S.Kormarneni, et al, Mater, Res. Soc. Symp, Proc. 1984, 32
    5 R.A. Vaia, E. R Giannelis, Polymer, 2001.42:1281
    6 G.-M. Kim, D.-H. Lee, et al, Polymer. 2001.42:1095
    7 D. J. Sub, Y. T. Lim, O. O. Park, Polymer, 2000, 41:8557
    8 Jian-Xiong Li, Jingshen Wu, Chi-Ming Chan, Polymer, 2000,41:6935
    9 漆宗能,等,中国专利,CN1138593A,1996
    10 陈光明,沈德言,等,高等学校化学报,2000,21(4):657
    11 周重光,李桂芝,等,高分子材料科学与工程,2000,16(2):109
    12 董元彩,孟卫,等,塑料工业,1999,27(6):37
    13 刘立敏,朱晓光,漆宗能,高分子学报,1999,(3):274
    14 舒中俊,陈光明,漆宗能,塑料工业,2000,28(3):24
    15 Yoshitsugu Kojima, Arimitsu Usuki, MasayavKawasumi, et al, Journal of Polymer Science: Part A: Polymer Chemistry, 1993, 31:983~986
    
    
    16 Yoshitsugu Kojima, Arimitsu Usuki, MasayavKawasumi, et al, Journal of Polymer Science: Part A: Polymer Chemistry, 1993, 31:1755~1758
    17 Masaya Kawasumi, Naoki Hasegawa, et al, Macromolecules, 1997, 30:6333~6388
    18 Yang Y, Zhu ZK, Yin J, Wang XY, Qi ZN, Polymer, 1999, 40:4407~4414
    19 Strawhecker KE, Manias E, Chem. Mater. 2000, 12:2943~2949
    20 王胜杰,李强,等,高分子学报,1998,(2):149~153
    21 邹志明,章永化,龚克成,中国塑料,2000,14(11):81~83
    22 Tsai HL, Schindler JL, Kannewurf CR, Kanatzidis G, Chem. Mater., 1997, 9:875~878
    23 Gilman JW, Jackson CL, Morgan AB, et al, Chem. Mater., 2000, 12:1866~1873
    24 罗谷风主编,基础结晶学与矿物学,南京大学出版社,1993
    25 Richard A. Vaia, Emmanuel P.Giannelis, Macromolecules, 1997, 30:7990~7999
    26 Cheon Il Park, O Ok Park, et al, Polymer, 2001, 42:7465
    27 吴人杰主编,现代分析技术,上海科技出版社
    28 M. Okamoto, S. Morita, T. Kotaka, Polymer, 2001, 42:2685
    29 E. Reynaud, T. Jouen, et al, Polymer, 2001, 42:8759
    30 Masami Okamoto, Satoshi Morita, et al, Polymer, 2000, 41:3887
    31 赵竹第,李强,等,高分子学报,1997,(5):519
    32 J.S. Shelley, P. T. Mather, K. L. DeVries, Polymer, 2001, 42:5849
    33 T. Agag, T.Koga, T. Takeichi, Polymer, 2001, 42:3399
    34 X. Kornmann, H. Lindberg, L. A.Berglund, Polymer, 2001, 42:1303
    35 T.-K. Chen, Y.-I. Tien, K.-H. Wei, Polymer, 2000,41:1345
    36 Richard A. Vaia, Emmanuel P. Giannelis, Macromolecules, 1997,30:8000~8009
    37 J.W. Cho, D. R. Paul, Polymer, 2001,42:1083~1094
    38 T.D.Fornes, P.J.Yoon, H. Keskkula et al, Polymer, 2001, 42:9929
    
    
    39 Richard A. Vaia, Klaus D. Jandt, et al, Macromotecutes, 1995, 28:8080
    40 M. Zanetti, G. Camino, et al, Polymer, 2001, 42:4501
    41 T.D. Fornes, P.J. Yoon, et al, Polymer, 2001,42:9929
    42 Jun-Chao Huang, Zi-Kang Zhu, Jie Yin, Xue-feng Qian, Polymer. 2001,42:873~877
    43 Michael Alexandre, Philippe Dubois, Materials Science and Engineering, 2000,28:1~63
    44 R.A. Vaia, R.K. Teukolsky, E.P.Giannelis. Chem. Mater. 1994,6:1017~1022
    45 卢红斌,杨玉良,高分子通报,2001,(6):18~26
    46 A. J. Poslinski, M. E. Ryan, R. K. Gupta, S. G. Seshadri and F. J. Frechette. Journal of Rheology, 1988.32(7):703~735
    47 Mirta I. Aranguren, Elsi Moro. Jon V. Degroot. et al, Rheotogy, 1992, 36(6): 1165~1182
    48 A.J. Poslinski. M.E. Ryan. R.K. Gupta, et al. Journal of Rheology, 1988, 32(7):703~735
    49 R. Krishnamoorti. and E. P. Giarmelis, Macromolecules, 1997. 30, 4097~4102
    50 J. Ren. A. S. Silva, and R. Krishnamoorti, Macromotecutes, 2000, 33, 3739~3746
    51 M.J. Solomon, A.S. Almusallam, K.F. Seefeldt, Macromotecutes, 2001, 34: 1864~1872
    52 R. Krishnamoorti, K. Yurekli, Current Opinion in Colloid & Interface Science. 2001,6:446~470
    53 E. P. Giannelis, R. Krishnamoorti, E. Manias, Adv. Polym. Sci. 1999, 138:107~147
    54 B. Hoffmann, C. Dietrich, Thomann, C. Friedrich, et al, Macromotecute Rapid Communication, 2000, 21:57~61
    55 G. Galgali, C. Ramesh, A. Lele, Macromolecutes, 2001, 34:852~858
    56 R. Krishnamoorti, J. Ren, A.S. Silva. J. Chem. Phys. 2001,114:4968~4973
    
    
    57 漆宗能,尚文宇,聚合物/层状硅酸盐纳米复合材料理论与实践,化学工业出版社,2002, 114~116
    58 P. Dubois, M. Alexandre, F. Hindryckx, R. Jéróme, Homogeneous polyolefin-based composites, J. Macromol. Sci.:Rev. Macromol. Chem. Phys. 1998, C38:511~565
    59 Shaofeng Wang, Yuan Hu, Qu Zhongkai, et al, Materials Letters, 2003, 57:2675~2678
    60 Jinguo Zhang, Charles A. Wilkie, Polymer Degradation and Stability, 2003, 80:163~169
    61 T.G. Gopakumar, J.A. Lee, M. Kontopoulou, J. S. parent, Polymer, 2002, 43:5483~5491

© 2004-2018 中国地质图书馆版权所有 京ICP备05064691号 京公网安备11010802017129号

地址:北京市海淀区学院路29号 邮编:100083

电话:办公室:(+86 10)66554848;文献借阅、咨询服务、科技查新:66554700