A solution mixing technique along with three organically modified montmorillonites (O-MMTs, denoted 15A, 20A and 30B), respectively,
were used to prepare polypropylene (PP)-based composites. X-ray diffraction (XRD) and transmission electron microscopy (TEM)
analyses confirmed the O-MMTs were intercalated and/or partially exfoliated within the PP matrix to different extents. The
PP/O-MMT nanocomposites were thus achieved without employing any compatibilizer. The 15A was noted to exhibit the best nano-scaled
dispersion status among the O-MMTs used, which was attributed to its more organophilic characteristic. Differential scanning
calorimetry (DSC) results indicated the O-MMTs improved the crystallization ability of PP slightly in the composites, whereas
the melting temperature of PP hardly changed. Thermogravimetric analysis (TGA) confirmed the thermal stability enhancement
of PP after adding the O-MMTs; the enhancement followed the order of PP/20A system > PP/15A system > PP/30B system. XRD results
also revealed the existence of predominant α form PP crystals along with a minor amount of γ form crystals in the composites. 相似文献
PA6/PP nanocomposites with either polyethylene octene elastomer grafted maleic anhydride (POEgMAH) or PP grafted maleic anhydride (PPgMAH) as compatibilizer were prepared using co-rotating twin-screw extruder followed by injection molding. The mechanical and microstructural properties of the composites were investigated by means of tensile, flexural, and impact testing and by scanning electron microscopy (SEM). X-ray diffraction (XRD) was used to characterize the formation of nanocomposites. The result indicated that the miscibility of PA6/PP nanocomposites was improved with the addition of POEgMAH and PPgMAH. The impact strength of PA6/PP nanocomposite with POEgMAH increased about 5 times higher than uncompatibilized composite. Increment in tensile properties was observed when PPgMAH was used as compatibilizer. XRD results revealed that PA6/PP nanocomposites were successfully formed. Uniform dispersion of PP in matrix were observed through SEM, which showed the improvement of the compatibility between polymers. 相似文献
Morphological, thermal and mechanical properties of blends prepared from polypropylene (PP) and 1, 3 and 5 wt% of vermiculite (VMT) were studied. The samples were prepared in a twin-screw extruder. The addition of maleic anhydride-functionalized polypropylene (PP-g-MAH) was also investigated. The blend morphologies were determined by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The thermal properties of the composites were investigated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The DSC results showed that PP crystallizes on cooling at higher temperatures as VMT content increases. The increase in crystallization temperature was most evident for blends with 5 wt% VMT. The TGA results showed that the use of VMT particles to fill polypropylene increased the thermal stability of the composite. The mechanical properties, tensile modulus and tensile strength at yield point of the PP improved by the presence of VMT. 相似文献
Acrylonitrile‐butadiene‐styrene (ABS)/clay nanocomposites have been prepared using two types of ABS with different AN contents and a chemically modified clay, Cloisite 20A. The composites were prepared by melt mixing in a twin‐screw extruder. Their morphological properties were characterized by XRD and TEM. The thermal stability of the polymer nanocomposites was studied using TGA and flammability tests. The results were analyzed in terms of the effect of the clay content and the type of ABS used on the clay dispersion and the thermal stability of the nanocomposites. Experimental results confirmed that better dispersion and intercalation and/or exfoliation can be obtained when using an ABS with a higher AN content. The study using TGA and flammability tests showed that the nanodispersed layers of silicate enhanced the thermal stability of the ABS matrix, and that an ABS with higher AN content was more effective in providing fire retardancy. This suggests that when using higher AN contents, more polar groups are present within the polymer matrix, allowing a more homogeneous dispersion and intercalation of the chain polymers into the organomodified montmorillonite clay (MMT), and even some exfoliation of the nanoclay.
Ferroelectric strontium barium niobate (SBN)-doped Na2O–B2O3–SiO2 (NBS) glass nanocomposites were prepared by dispersing sol–gel-derived SBN powder into fused NBS glass. Their structures were characterized by X-ray diffractometry and Raman spectroscopy. The dielectric constants were measured as functions of frequency and temperature using an impedance analyzer. The ferroelectric-to-paraelectric-phase transition was studied by differential scanning calorimetric analysis. Our results revealed that the embedded SBN has lower phase transition temperature and phase transition heat than those of SBN bulk materials. Their activation energy, however, is larger than that of SBN ultra-fine powders. Pure tetragonal-phase SBN nanocomposites can be obtained at annealing temperatures of 750°–1000°C. Their dielectric constants are ∼32–46 and ∼20–25 at low frequencies and radio frequencies, respectively, and the loss tangent is <0.1 at room temperature in the radio frequencies range. Our studies suggested that additional reduction in the loss properties must be made before these systems can be considered for application as microwave dielectric materials. 相似文献
In this work we report the investigation of the dynamics of maleic anhydride grafted polypropylene (PPgMA) and PPgMA-based nanocomposites by means of dielectric relaxation spectroscopy (DRS) and dynamic mechanical thermal analysis (DMTA). After characterization of neat PPgMA, we study the effect of organically modified silicate filler on the dynamics of PPgMA with dynamic mechanical thermal analysis. Our results suggest that the β-relaxation process, corresponding to the glass transition of PPgMA, is affected by the clay loading. The glass-transition temperature of PPgMA increases in a composition with filler content of 30 wt.%, probably because of polymer-filler interactions, which reduces the polymer chain mobility. In the nanocomposite materials a separate high temperature process due to Maxwell-Wagner-Sillars (MWS) polarization was observed with dielectric relaxation spectroscopy. 相似文献
Both polypropylene (PP) and PP/organo-montmorillonite (OMMT) masterbatch containing antistatic agent (3–9 wt%) were prepared by using co-rotating twin screw extruder followed by injection molding. PP/OMMT masterbatch was prepared by mixing PP, OMMT and maleated PP (PPgMAH). The PP nanocomposites were characterized by using X-ray diffractometer (XRD), differential scanning calorimeter (DSC), thermogravimetry analyzer (TGA), hardness and surface resistivity tests. XRD results indicated that AA could promote the intercalation in PP/OMMT nanocomposites. The decomposition temperature of PP/OMMT/AA nanocomposites is higher than that of PP/OMMT. The hardness, degree of crystallinity and surface resistivity of PP nanocomposites was influenced by the addition of antistatic agent. 相似文献
Bentonite was modified with trialkylaluminum to prepare polypropylene/clay nanocomposites. Treated clay, commercial polypropylene, and a coupling agent were mixed in miniextruder. To obtain the masterbatches and dilutions, two polypropylene grades were used to analyze the influence of molar mass on clay dispersion. The screw rotation varied from 30 to 200?rpm, and the clay content was 1, 2, and 5?wt%. For samples prepared with higher molar mass, increasing speed from 30 to 200?rpm improved the clay dispersion. For processing with lower molar mass, decreasing speed from 60 to 30?rpm caused an increase in viscosity, resulting in better dispersion. 相似文献