The effect of polypropylene (PP) molecular weight on the properties of styrene-butadiene-styrene block copolymer (SBS)/PP blends was studied. All SBS/PP blends (50/50 and 90/10) exhibited a sandwich structure where the co-continuous SBS/PP layer was between the top and bottom PP layers. Solvent extraction tests suggested that the continuous phase structure of PP was independent of the blending ratio and PP molecular weight, while the SBS phase changed from a dispersed phase to a continuous phase as the SBS content increased. The decrease in PP molecular weight decreased the PP layer thickness but increased the phase domain size of SBS in SBS/PP(50/50) blends. As a result, less noticeable "stress-hardening" phenomenon was observed. The mechanism for the structural change was attributed to the different melt viscosities of each component. The crystallinity of the blends did not change with the variable PP molecular weight but decreased with the increasing SBS content.
Polycarbonates (PCs) are commonly used as a blend and a composite to achieve pecuniary advantages and dimensional stability. While the toughness of a homogeneous PC matrix has been extensively investigated, examination for the toughness of heterogeneous blend systems such as PC/polypropylene (PP) blends has been limited. Furthermore, recent interest in highly flowable PCs (low-molecular-weight PCs with low ductility) has surfaced due to the large and geometrically complex plastic parts. Herein, the toughness for PC/PP blends and PC/PP/talc composites in a ductile and a brittle PC matrix was explored by using various toughness measurements such as notched Izod impact strength, falling dart impact, boss quasi-static energy/impact energy, and tensile toughness tests. In a ductile PC matrix [melt flow index (MFI)=8], the incorporation of PP gradually reduced the toughness. On the other hand, the toughness was improved by 450% at 2 wt % PP in a brittle PC matrix (MFI=19). Similarly, in the talc-induced brittle PC matrix, the toughness was enhanced at the PP loading from 2 to 10 wt %. The density of PC/PP blends was gradually reduced from 1.19 to 1.10 gcm(-3) with increasing PP concentration from 0 to 20wt %. Degradation, density, thermal behaviors, and morphology were also investigated. (c) 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47110.
来源期刊：Polymer: The International Journal for the Science and Technology of Polymers
Grafting polyolefin chains onto the surface of silica nanoparticles to form satisfactory polyolefin/silica nanocomposites still remains a challenge, even after the complicated functionalization of the polyolefin chains and surface modification of the silica. In this study, an efficient route for the preparation of polypropylene-grafted nanosilica (PP-g-SiO2) masterbatch was presented through the reactive melt blending of maleic-anhydride-grafted polypropylene (PP-MAH) and amino-functionalized silica (SN-NH2) synthesized by the co-condensation method. The amount of grafted PP chains could achieve to 80.8 wt%. And PP-g-SiO2 exhibited fine dispersion in PP matrix. The shear and extension rheology results of PP/PP-g-SiO2 nanocomposites showed that melt strength of PP could be enhanced remarkably by incorporation of PP-g-SiO2 masterbatch, which revealed the strong interactions between PP-g-SiO2 and PP matrix. These findings provide a facile way to prepare polyolefin-grafted nanosilica, while expanding the potential applications of nanosilica in polyolefin nanocomposites. (C) 2018 Elsevier Ltd. All rights reserved.
A uniform, monodispersed superfine cuprous oxide (Cu2O) sphere with a mean diameter of 850 nm has been synthesized by solution reduction. The study reported the synthesis and thermal properties of Cu2O/PP composites for the first time. The surface modification of the superfine Cu2O sphere was carried out by using a silane coupling agent KH-570. Fourier-transform infrared (FTIR) spectroscopy and the thermogravimetric analysis (TGA) curve revealed that the Cu2O had been successfully modified by silane coupling agent KH570. The scanning electron microscope (SEM) shows that the modified Cu2O can be uniformly dispersed in the polypropylene (PP) matrix, because through surface modification, there are some active functional groups on its surface, such as the ester group, which improves its compatibility with the PP matrix. The thermal stability of Cu2O/PP composites was improved by adding a small amount of Cu2O (1 wt % of PP). Therefore, based on the potential bacteriostasis of cuprous oxide, the low cost of PP and the results of this study, it is predicted that Cu2O/PP composites can be used in infant preparation (such as milk bottles) with low cost and good thermal stability in the near future.
Polypropylene/thermoplastic polyurethane (PP/TPU) blends of different weight ratios (75/25 and 25/75) were processed by melt blending using a maleic anhydride-grafted polypropylene (PP-g-MA) copolymer as coupling agent. The influence of the amount of the coupling agent (0, 3, 5, 7, 9, 11 phr) on the mechanical, frictional, and wear properties of the blends were characterized through tensile test, three-point bending, dynamic mechanical analysis (DMA), and ball-on-disc wear tests. PP-g-MA was found to be an effective compatibilizer for PP/TPU blends, and mechanical and wear properties of the blends were proved to be strongly impacted by the amount of coupling agent. Tensile strength of the blends tends to increase with increasing the PP-g-MA content and 9 phr is found to be optimal for both concentrations of the blends. Good miscibility of the blends with increasing compatibilizer content was also verified by DMA. From the wear test results, the compatibilizer was found to be more effective in PP75/TPU25 blends, in parallel with the results of the mechanical tests. The PP75/TPU25 blend with 11 phr PP-g-MA content was superior to the other blends. In addition, in this work, a new model based on image processing is proposed that provides accurate and fast wear rate measurement and detailed information of the wear track, especially in heterogeneous materials. Using the model, the homogeneity of the wear track widths was proved to be strongly impacted and improved by the use of a coupling agent.
Guopeng Sui;Mengfan Jing;Jing Zhao;Ke Wang;Qin Zhang;Qiang Fu
来源期刊：Polymer: The International Journal for the Science and Technology of Polymers
Exerting high shear force and adding compatilizer are two different methods used for regulating the size of dispersed phase of polymer blends. Nevertheless, the comparison of the effect of the high shear force and adding compatilizer on the phase morphologyies and properties is less studied, not to mention the synergistic effect. In this work, the incompatible PP/PLA binary blends with large polarity differences were prepared using high-shear processing, compared with the effect of adding ethylene-(methyl acrylate)-(glycidyl methacrylate) (EMA-GMA) as reactive compatibilizer for PP/PLA blends. It was found that adding compatilizer under relative low shear force was more efficient on improving the interface, showing blurred boundaries, compared with the reduction of the dispersed phase size under high shear force without compatilizer. As a result, the blends with the compatilizer presented a higher elongation at break; yet the yield strength of the binary blends prepared under high shear force was higher than that of the ternary blends. Furthermore, the synergistic effect of adding compatibilizer and high shear force was limited, which could be attributed to the fact that the degree of reactive compatibilization had already reached saturation under the rotation speed of 100?rpm due to the high efficiency of EMA-GMA.
Ramazanov, M. A.;Hajiyeva, F. V.;Maharramov, A. M.;Hasanova, U. A.
The influence of corona discharge on the structure and photoluminescence properties of nanocomposites based on polypropylene and zirconium dioxide nanoparticles has been studied. It is shown that after the polarization under the influence of corona discharge surface roughness of polarized sample was for 40-60 nm whereas for unpolarized compositions it was 80-120 nm, i.e. the grinding of structural element took place. It was found that, after the polarization, the intensity of the photoluminescence increases depending the concentration. In order to determine the cause of the increase in the intensity of the luminescence by TSD method the stored charge at the interface between the components of the nanocomposite was studied. It has been shown that the polarization process led to accumulation of sufficiently large amount of electric charges at the interface between the components of the nanocomposite PP + ZrO2. The intensity of the internal local field of charges was calculated, and it was found that it creates a high internal local field due to the border charges. As a result, the luminescence intensity rose after increasing the value of the polarization.
For advanced water treatment, effects of pH and pure polypropylene (PP) beads packing concentration on membrane fouling and treatment efficiency were observed in a hybrid process of alumina ceramic microfiltration (MF; pore size 0.1m) and pure PP beads. Instead of natural organic matters and fine inorganic particles in natural water source, a quantity of humic acid (HA) and kaolin was dissolved in distilled water. The synthetic feed flowed inside the MF membrane, and the permeated water contacted the PP beads fluidized in the gap of the membrane and the acryl module case with outside UV irradiation. Periodic air back-flushing was performed to control membrane fouling during 10s per 10min. The membrane fouling resistance (R-f) was the maximum at 30g/L of PP bead concentration. Finally, the maximum total permeated volume (V-T) was acquired at 5g/L of PP beads, because flux maintained higher all through the operation. The treatment efficiency of turbidity was almost constant, independent of PP bead concentration; however, that of dissolved organic materials (DOM) showed the maximal at 50g/L of PP beads. The R-f increased as increasing feed pH from 5 to 9; however, the maximum V-T was acquired at pH 6. It means that the membrane fouling could be inhibited at low acid condition. The treatment efficiency of turbidity increased a little, and that of DOM increased from 73.6 to 75.7% as increasing pH from 5 to 9.
Melt-mixing of immiscible polymers can form a broad range of heterogeneous blend system. In this study, polypropylene (PP)/cyclic olefin copolymer (COC) blends were processed in a co-rotating twin screw extruder by melt processing technique. PP/COC blends were prepared without compatibilizer as COC is expected to be compatible with polypropylene due to its olefinic behaviour. Effects of COC blending with PP on mechanical, dynamic mechanical, rheological and morphological behaviour were investigated thoroughly. An increasing fraction of stiffened COC in the PP/COC blends is responsible for the enhancement of tensile strength and modulus, flexural strength and modulus and of a decrease in the elongation at break and impact energy. Various blend system models, such as Parallel, Series, Coran, Takayanagi, Kerner and Halpin Tsai models, have been used to predict tensile strength and modulus and compared with experimental data. When COC is added, shear viscosity of PP/COC blends increases compared to pure PP. The high shear rheological behaviour of PP/COC blends displayed non-Newtonian and shear-thinning behaviour. Shear viscosity as functions of blend composition shows negative deviation from the expected log linearity. DMA results established immiscibility of PP and COC in the blend system, by providing independent glass transition (Tg) for PP and COC component. Scanning electron microscopy results revealed fibrillar morphology for PP/COC blends and co-continuous behaviour in the PP50/COC50 blend composition. The intention of the prepared PP/COC blends is to enhance polypropylene properties by forming COC co-continuous phase, which should impart to the polypropylene phase higher tensile strength, tensile modulus, flexural strength and flexural modulus. The application of optimized PP/COC blend composition is to fabricate dimensionally stable artifacts compared to that of pure PP.