纳米二氧化硅／MC尼龙6原位复合材料非等温结晶动力学

通过阴离子开环聚合法制各纳米二氧化硅／MC尼龙6原位复合材料,采用差示扫描量热法研究MC尼龙6及其原位纳米复合材料非等温结品行为,并利用修正Avrami方程的Jeziomy和Liu的方法进一步处理原位纳米复合材料的非等温结晶动力学,结果表明在纳米二氧化硅／MC尼龙6原位复合材料中,纳米二氧化硅对基体MC尼龙6的结晶有一定的成核作用,并提高了其结品速率。     

Mechanical and rheological properties of PP/SEBS/OMMT ternary composites

The microstructure and mechanical properties of polypropylene (PP)/OMMT binary nanocomposites and PP/styrene‐6‐(ethylene‐co‐butylenes)‐6‐styrene triblock copolymer (SEBS)/OMMT ternary nanocomposites were investigated using X‐ray diffraction (XRD), transmission electron microscopy (TEM), and rheology and electromechanical testing machine. The results show that the organoclay layers are mainly intercalated and partially exfoliated in the PP‐based nanocomposites. The additions of SEBS and OMMT have no significant effect on the crystallization behavior of PP. At the same time, it can be concluded that the polymer chains of PP and SEBS have intercalated into the organoclay layers and increase the gallery distance after blending process based on the analytical results from TEM, XRD, and rheology, which result in the form of a percolated nanostructure in the PP‐based nanocomposites. The results of mechanical properties show that SEBS filler greatly improve the notched impact strength of PP, but with the sacrifice of strength and stiffness. OMMT can improve the strength and stiffness of PP and slightly enhance the notched impact strength of PP/PP‐g‐MA. In comparison with neat PP, PP/OMMT, and PP/SEBS binary composites, notched impact toughness of the PP/SEBS/OMMT ternary composites significantly increase. Moreover, the stiffness and strength of PP/SEBS/OMMT ternary nanocomposites are slightly enhanced when compared with neat PP. It is believed that the synergistic effect of both SEBS elastomer and OMMT nanoparticles account for the balanced mechanical performance of the ternary nanocomposites. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Studies on crystallization behaviors and crystal morphology of polyamide 66/clay nanocomposites

X‐ray diffraction methods, DSC thermal analysis, and polarized light microscopy (PLM) were used to investigate the structural changes of nylon 66/clay nanocomposites. PA 66/clay nanocomposites were prepared by the method of melt intercalation. The results indicate that the addition of the intercalated organo‐montmorillonite (OMMT) can induce generation of the β‐form crystal of PA 66 and substantially affect the arrangement of molecules in the α‐form crystal, although the crystallinity scarcely changes. Also, the DSC results indicate that the addition of OMMT in the PA 66 matrix leads to increases of crystallization temperatures and the full width at half maximum (FWHM) of the exothermic peaks. Moreover, the viscosity factor is the main influence on FWHM of the exothermic peaks of PA 66/clay nanocomposites. The results of nonisothermal crystallization kinetics show that OMMT has the effect of heterogeneous nucleation and leads to the decrease of the size of the spherocrystal. The heterogeneous nucleation effects of OMMTs influence the mechanism of crystallization and the growth mode of PA 66 crystals. PLM photographs verify that the size of spherocrystal is decreased and visually confirm the theory of crystallization kinetics. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 756–763, 2005     

Non-isothermal crystallization of monomer casting polyamide 6/functionalized MWNTs nanocomposites

Monomer casting polyamide 6(MCPA6)/toluene 2,4-diisocyanate functionalized multi-walled carbon nanotubes (MWNTs-NCO) nanocomposites were prepared via in situ anionic ring opening polymerization, and the non-isothermal crystallization behavior of the nanocomposites were investigated by differential scanning calorimetry with various cooling rates. The commonly used Avrami, Ozawa, Mo, and Urbanovici–Segal models were employed to analyze the non-isothermal crystallization data and the validity of the models on the process of MCPA6 and its nanocomposites was discussed, where Mo and Urbanovici–Segal models could well describe the non-isothermal crystallization process for the samples. The results revealed that MWNTs could accelerate the crystallization process of MCPA6, attributing to the nucleating effect of the nanofillers. Finally, the effective energy barrier for non-isothermal crystallization was evaluated as a function of the relative crystallinity by applying an isoconversional method.     

Polypropylene/montmorillonite composites and their application in hybrid fiber preparation by melt‐spinning

Polypropylene (PP)/organomontmorillonite (OMMT) nanocomposites have been successfully prepared by melt intercalation by using the conventional method of twin‐screw extrusion and subsequently submitted for melt‐spinning. The structure and properties of the PP/clay nanocomposites and hybrid fibers were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X‐ray diffraction (XRD), differential scanning calorimetry (DSC), and crystallization dynamics, etc. The organoclay layers were found to disperse in the PP resin at the nanometer level. The nanoscaled OMMT layers, dispersed in the PP matrix, actually played the role of heterogeneous nuclei species in the process of PP crystallization and increased the nucleation speed of the composites, hereby leading to the increase of crystallization rate of the as‐spun fiber. Meanwhile, it was found that the crystallinity of PP/OMMT hybrid fibers is much higher than that of pure PP fiber at the same draw ratios, whereas the orientation of PP/OMMT hybrid fibers is much lower than that of pure PP fiber at the same draw ratios. Because of the effective intercalation of OMMT into PP matrix, the nanocomposites have good spinnability, and the moisture absorption of the final PP fiber is improved. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 552–558, 2004     

Non-isothermal crystallization kinetics of polypropylene/MAP-POSS nanocomposites

Non-isothermal crystallization kinetics of polypropylene (PP)/methylacryloypropy polyhedral oligomeric silsesquioxanes (MAP-POSS) nanocomposites (PP/MAP-POSS) were investigated by DSC at various cooling rates. Jeziorny and Mo method were used to study the non-isothermal crystallization kinetics. The results show that the Jeziorny and Mo method are all successful in describing the non-isothermal crystallization kinetics of PP/MAP-POSS nanocomposites. The MAP-POSS can act a role of heterogeneous nucleation and increase the crystallization rate constant Z _c and decrease crystallization half time t _1/2, and the spherulite crystal size decreases, the inter-spherulitic action or crosslinking structure each other appear at the appropriate content. The DSC peak temperature T _p increase about 5 °C, t _1/2 reduce 0.21 min at 6 % content of MAP-POSS and heating rate of 10 °C/min. The MAP-POSS can also increase the mechanical property of PP/MAP-POSS nanocomposites, the tensile strength and impact strength increase from 12.97 to 19.93 MPa and from 33.2 to 52.6 kJ/m², respectively, at 4 % content of MAP-POSS. But the spherulitic crystal becomes larger and boundaries become clearer again; the macrophase separation will occur and mechanical properties decrease when more and more MAP-POSS was added. The nanocomposite has the best mechanical property at 4 % content of MAP-POSS.     

BR/CB/OMMT纳米复合材料的结构与性能研究

采用溶液插层法与双辊混炼法制备了顺丁橡胶/炭黑/有机蒙脱土（BR/CB/OMMT）纳米复合材料,用透射电子显微镜（TEM）以及X射线衍射（XRD）方法对复合材料的亚微观结构进行了表征,并研究了复合材料的力学特性、耐磨耗性能以及硫化特性。结果表明：BR/CB/OMMT为插层型纳米复合材料;在OMMT含量小于4份时,BR/CB/OMMT纳米复合材料具有优异的力学性能和耐磨耗性能;OMMT起到了硫化促进剂的作用,降低了BR的焦烧时间（TS）和正硫化时间（T90）;低填充量OMMT可提高复合材料的交联密度。     

Effect of functionalized SWCNTs on microstructure of PP‐g‐MA/OMMT/f‐SWCNTs nanocomposite

The aim of this work was to study the effect of functionalized single‐walled carbon nanotubes (f‐SWCNTs) on the microstructure of PP‐g‐MA/organic modified montmorillonite (OMMT)/f‐SWCNTs ternary nanocomposite. Pristine SWCNTs were chemically modified by maleic anhydride to improve the interaction between PP‐g‐MA and nanotubes. The dispersion states of OMMT in the different nanocomposites were investigated by wide angle X‐ray diffraction. The morphologies of the nanocomposites were characterized by scanning electron microscopy. Crystallization behaviors of nanocomposites were studied through differential scanning calorimetry and polarizing optical microscopy. Different than the PP‐g‐MA/OMMT binary nanocomposite, in which the OMMT is mainly in an exfoliated state, the ternary PP‐g‐MA/OMMT/f‐SWCNTs nanocomposite exhibits mostly intercalated OMMT. Furthermore, in the ternary nanocomposite, the crystallization of polymer is mainly induced by f‐SWCNTs rather than by OMMT. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

OMMT对PE-HD/PA6合金的结晶性能和相容性的影响

研究了不同含量的有机蒙脱土（OMMT）对高密度聚乙烯/聚酰胺6（PE-HD/PA6）合金的结晶性能和微观结构的影响。X射线衍射和差示扫描量热仪分析表明,随着OMMT的含量的增加,PA6倾向于生成γ晶型;扫描电镜分析表明,对于PE-HD/PA6合金,PA6以球状分散在PE-HD基体中,相尺寸直径较大,为30~40 μm;添加OMMT后,PA6分子链的极性基团可以与OMMT层间表面产生强的相互作用,使得大分子链在熔融过程中进入OMMT层间,得到PE-HD/PA6/OMMT纳米复合材料。当添加3份OMMT后,复合材料中分散相PA6的相尺寸降低至10 μm,尺寸分布均匀,说明OMMT起到了相容剂的作用。同时,适量的OMMT提高了PE-HD/PA6合金对有机溶剂的阻透性。     

Rheology,Crystallization Kinetics and Mechanical Properties of HDPE/Vinyl-POSS Nanocomposites

Polyhedral oligomeric silsesquioxane (POSS) is usually prepared from the hydrolytic condensation of organotrialkoxysilanes. The rheology, non-isothermal crystallization kinetics and mechanical properties of high density polyethylene (HDPE)/vinyl-containing POSS (V-POSS) nanocomposites were investigated. The results show that the molten HDPE/V-POSS belong to pseudoplastic fluid. The V-POSS can accelerate the nucleation of HDPE at starting stage of crystallization. However, it will decrease the crystallization ability of HDPE in the subsequent crystallization process. The modified Avrami analysis by Jeziorny can well explain the crystallization behaviour of HDPE/V-POSS. The yield strength and tensile modulus of nanocomposites both increase when V-POSS content is 6%.     

PA6/POE/OMMT纳米复合材料的流变行为

使用毛细管流变仪研究了尼龙6/乙烯-辛烯共聚物/有机改性蒙脱土(PA6/POE/OMMT)纳米复合材料的流变行为,并对lgΥω-lgγω、lgηα-lgγω、lgηα-1/T曲线进行了分析.研究结果表明,PA6/POE/OMMT纳米复合材料为假塑性流体,其表观粘度随着剪切应力的增加而降低;OMMT使得PA6/POE纳米...     

原位增容PA6/PE-HD共混物的非等温结晶动力学研究

利用差示扫描量热仪研究了原位增容的聚酰胺6/高密度聚乙烯（PA6/PE-HD）共混物的非等温结晶过程,用经Jeziorny 修正的Avrami方程和Mo法对其非等温结晶动力学进行了研究,计算并得到非等温结晶动力学参数。结果表明,该方程和方法适合于处理纯PA和PA6/PE-HD共混物的非等温结晶过程;在PA6/PE-HD共混物非等温结晶过程中, 在其初期结晶阶段可能同时包含了均相成核和异相成核, 在二次结晶阶段结晶生长可能是一维生长,并且PE-HD的加入,起到异相成核的作用,促进了晶核的生长。此外, 还利用Vyazovkin的方法求出PA6/PE-HD共混物结晶活化能与温度之间的关系。     

Preparation of PET/clay nanocomposites via in situ polymerization in the presence of monomer‐activated organoclay

Various polyethylene terephthalate (PET)/clay nanocomposites containing a commercial organoclay (organophilic montmorillonite nanoclay [OMMT]) and a monomer‐activated OMMT (remodified OMMT) were prepared via in situ interlayer polycondensation of dimethyl terephthalate and ethylene glycol. In order to remodify the commercial OMMT nanoparticles, a diacid chloride monomer was applied. The prepared nanocomposites were characterized by diverse methods, including X‐ray diffraction, differential scanning calorimetry, thermogravimetric analysis, and intrinsic viscosity measurements. The results of the study revealed that the PET/(remodified OMMT) nanocomposites possess a better state of clay dispersion as well as significantly better thermal properties as compared with the PET/OMMT nanocomposites. Moreover, the PET/(remodified OMMT) nanocomposites showed higher crystallization temperature, degree of crystallinity, maximum degradation temperature, and lower half‐time of crystallization than that of the PET/OMMT nanocomposites. It was found that the remodification process for OMMT led to less of a foaming problem during in situ polymerization. J. VINYL ADDIT. TECHNOL., 21:70–78, 2015. © 2014 Society of Plastics Engineers     

Structure and properties of polypropylene/clay nanocomposites compatibilized by solid‐phase grafted polypropylene

Polypropylene/organic‐montmorillonite (PP/OMMT) nanocomposites were prepared via a solid‐phase PP graft (TMPP) with a higher grafting level as the compatibilizer. The effects of the compatibilizer on the structure and properties of PP/OMMT nanocomposites were investigated. The structure of the nanocomposites were characterized by X‐ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The results showed that when the weight ratio of TMPP and OMMT is greater than 1:1, the OMMT can be dispersed in PP matrix uniformly at the nanoscale. The mechanical properties of the nanocomposites reached a maximum when the weight ratio of TMPP and OMMT is 1:1, although more uniform dispersion was achieved at a higher content of TMPP. The mechanical properties of the nanocomposites decrease with the content of TMPP. The crystallization behavior, dynamic rheological property, and thermal stability of the nanocomposites were investigated by differential scanning calorimetry (DSC), dynamic rheological analysis, and thermal gravimetric analysis (TGA), respectively. Due to the synergistic effects of TMPP and OMMT on the crystallization of PP, the crystallization peak temperature of the nanocomposites increased remarkably compared with that of the neat PP. TMPP shows β‐phase nucleating ability and OMMT promotes the development of β‐phase crystallite. The nanocomposites show restricted melt flow and enhanced temperature sensitivity compared with the neat PP. The thermal stability of the nanocomposites is obviously improved compared with that of the neat PP. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers.     

PEN／MMT纳米复合材料结晶动力学的研究

采用熔融插层法制备聚2,6-萘二甲酸乙二酯(PEN)/蒙脱土(MMT) 纳米复合材料,用Avrami方程和张志英方法对所得数据进行了等温结晶和非等温结晶动力学的研究.结果表明,在PEN/MMT共混物中由于MMT的加入,降低了PEN/MMT的结晶活化能,导致共混物的结晶速率提高;MMT含量影响共混物的结晶速度,加入少量的MMT可以明显提高共混物的结晶速率;共混物的表面活化能的变化与Avrami方程得出的n值变化相似,MMT的含量影响共混物成核结晶速度.     

Study of polypropylene/montmorillonite nanocomposites prepared by solid‐state shear compounding (S3C) using pan‐mill equipment: the morphology of montmorillonite and thermal properties of the nanocomposites

In this paper, polypropylene (PP)/organophilic montmorillonite (OMMT) nanocomposites were successfully prepared without any compatibilizers by solid‐state shear compounding (S³C) using pan‐mill equipment. X‐ray diffraction (XRD) patterns show that the OMMT characteristic (001) peak at 2θ equal to 4.59 degrees disappeared for the milled OMMT and corresponding composites. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) photographs show that the thickness of pan‐milled OMMT decreased from ca 100–200 nm to ca 30–50 nm, and OMMT was partly exfoliated in the PP matrix because the pan‐type mill can exert fairly strong squeezing force in the normal direction and shearing force in both radial and tangential directions on milled materials. PP/OMMT nanocomposites at low OMMT loading have higher melting point, crystallization temperature, thermal degradation temperature and heat distortion temperature than those of neat PP. Moreover, addition of OMMT accelerates crystallization of PP significantly. S³C is a novel approach to prepare polymer/layered silicate nanocomposites with high performances at low filler loading. Copyright © 2004 Society of Chemical Industry     

PP/PA6/OMMT复合材料力学性能与结晶性能的研究

采用3种不同有机改性过的蒙脱土(牌号为DK2,DK3,DK5)熔融插层法制备了PP/PA6/OMMT纳米复合物材料,在此基础上使用1%～7%的DK2的蒙脱土再次制备PP/PA6/OMMT纳米复合物材料,借助力学性能测试和差示扫描量热法(DSC)对体系的力学性能和结晶性能进行了研究。结果表明:使用DK2制备的复合材料的力学性能优于使用DK3和DK5制备的复合材料的力学性能;相对于纯PP,PP/PA6/OMMT纳米复合物材料随OMMT含量的增加,拉伸强度和弯曲强度是先增加后降低,最大下降幅度分别为8.7%和5.3%;冲击韧性一直上升达到9.61kJ/m2。OMMT的加入,对PP/PA6有异相成核的作用,提高PP/PA6的结晶速率和结晶度。     

Water absorption and hygrothermal aging study on organomontmorillonite reinforced polyamide 6/polypropylene nanocomposites

The water absorption and hygrothermal aging behavior of organomontmorillonite (OMMT) reinforced polyamide 6/polypropylene (PA6/PP ratio = 70/30), with and without maleated PP (MAH‐g‐PP), was studied at three different temperatures (30, 60, and 90°C). The water absorption and hygrothermal aging response of the composites was studied and analyzed by tensile tests and morphology assessment (scanning electron microscopy and transmission electron microscopy), indicating the effect of the immersion temperature, OMMT, and MAH‐g‐PP compatibilizer. The mathematical treatment used in analyzing the data was the single free phase model of diffusion, which assumed Fickian diffusion and utilized Fick's second law of diffusion. The kinetics of water absorption of the PA6/PP nanocomposites conformed to Fickian law behavior, whereby the initial moisture absorption follows a linear relationship between the percentage gain at any time t and t^1/2 (the square root of time), followed by saturation. It was found that the equilibrium moisture content and the diffusion coefficient are dependent on the OMMT loading, MAH‐g‐PP concentration, and immersion temperatures. Both the tensile modulus and strength of the PA6/PP nanocomposites deteriorated after being exposed to hygrothermal aging. MAH‐g‐PP acted as a good compatibilizer for PA6/PP/OMMT nanocomposites, which was attributed to its higher retention ability in modulus and strength (in the wet and redried states), lower equilibrium moisture content, and reduced water diffusivity of the nanocomposites. Morphological sketches for both uncompatibilized and MAH‐g‐PP compatibilized PA6/PP/OMMT nanocomposites, toward water uptake are proposed. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 780–790, 2005     

Non-isothermal crystallization kinetics of Nylon 10T and Nylon 10T/1010 copolymers: Effect of sebacic acid as a third comonomer

Nylon 10T and Nylon 10T/1010 samples were synthesized by direct melt polymerization.The non-isothermal crystallization kinetics of Nylon 10T and Nylon 10T/1010 was investigated by means of differential scanning calorimetry (DSC).Jeziomy equation and Mo equation were applied to describe the non-isothermal crystallization kinetics of the Nylon 10T and the Nylon 10T/1010.The activation energies for non-isothermal crystallization were obtained by Vyazovkin's method and Friedman's method,respectively.These results showed that Jeziorny equation and Mo equation well described the non-isothermal crystallization kinetics of the Nylon 10T and the Nylon 10T/1010.It was found that the values of the activation energy for non-isothermal crystallization of the Nylon 10T/1010 were lower than those of the Nylon 10T at a given temperature or relative crystallinity degree,which revealed that crystallization ability of the Nylon 10T/1010 was higher.The crystal morphology was observed by means of a polarized optical microscope (POM) and X-ray diffraction (XRD).It was found that the addition of sebacic acid comonomer not only did not change the crystal form of the Nylon 10T,but also significantly increased the number and decreased the size of spherulites.Comparing with the Nylon 10T,the crystallization rate was increased with the addition of the sebacic acid comonomer.