Crystallization of PP in PP/Ni composites and its correlation with tensile properties

The effect of nickel (Ni) powder on crystallization of polypropylene (PP) in PP/Ni composites is studied through differential scanning calorimetry (DSC) and wide-angle X-ray diffraction techniques. Interpretation of crystallization exotherm peaks in terms of nucleation and growth rates of crystallization, crystallite size distribution, and crystallinity indicated differences in the morphology of PP in all the composites. Crystallinity and tensile behavior decreased on nickel addition. There is a good qualitative agreement in the crystallinity determined by X-ray diffraction and DSC exotherms, and the variation in both cases, with the volume percent of filler is similar. An attempt has been made to correlate the various tensile properties with the crystallization parameters such as the crystallinity and crystallite size distribution.     

Impact and tensile properties of SEBS copolymer compatibilized PS/HDPE blends

In this study, polystyrene–hydrogenated polybutadiene–polystyrene (SEBS) triblock copolymer was used as a compatibilizer for the blends of polystyrene (PS) and high-density polyethylene (HDPE). The morphology and static mechanical and impact properties of the blends were investigated by means of scanning electron microscopy, uniaxial tension, and instrumented falling-weight impact measurements. Tensile tests showed that the yield strength of the PS/HDPE/SEBS blends decreases considerably with increasing HDPE content. However, the elongation at break of the blends tended to increase significantly with increasing HDPE content. The excellent tensile ductility of the HDPE-rich blends resulted from shield yielding of the matrix. Charpy impact measurements indicated that the impact strength of the blends increases slowly with HDPE content up to 50 wt %; thereafter, it increases sharply with increasing HDPE content. The impact energy of the HDPE-rich blends exceeded that of pure HDPE, implying that the HDPE polymer can be further toughened by the incorporation of brittle PS minor phase in the presence of SEBS compatibilizer. The correlation between the impact property and morphology of the blends is discussed. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 1099–1108, 1998     

Tensile yield behavior of PP/SEBS blends

Tensile yield behavior of the blends of polypropylene (PP) and styrene–ethylene butylene–styrene block copolymer (SEBS) is studied in blend composition range 0–25 wt % SEBS. Three sets of samples, (i) solution-blended compression-molded (SBCM), (ii) melt-blended compression-molded (MBCM), and (iii) melt-blended injection-molded (MBIM), were studied to investigate the relative merits of solution blending and melt blending and the effect of subsequent mixing during injection moulding. Systematic changes with varying blend composition were found in stress–strain behavior in the yield region, viz., in yield stress, yield strain, width of yield peak, and work of yield. Growth of shear bands before necking also showed some systematic variation with blend composition. Shapes and sizes of dispersed-phase (SEBS) domains at various blend compositions were studied by scanning electron microscopy. Analysis of yield stress data on the basis of the various expressions of first power and two-thirds power laws of blend composition dependence and the porosity model (i.e., the exponential law) led to consistent results from all expressions about the variation of stress concentration effect in these sample sets; the stress concentration effect increased in the following order: MBIM < SBCM < MBCM. Furthermore, in addition to revealing relative suitability of the various expressions to the present system, this analysis also showed a transition around the blend composition 5 wt % SEBS from a continuous to a discontinuous structure. Solution blending produces lower degree of discontinuity in the structure of this two-phase blend than the melt blending, and this discontinuity in melt blended samples is reduced on subsequent mixing during injection-molding process.     

Influence of processing conditions on the mechanical properties of SEBS/PP/oil blends

A common type of thermoplastic elastomer is a blend of styrene-ethylene-butylene-styrene copolymer (SEBS) with polypropylene and mineral oil. The knowledge about the processing parameters that influence the blend of these components is important to achieve the best material properties. In this study, were evaluated the influence of screw configuration (low and high shear) and speed (200, 300, and 400 rpm), molding form (compression and injection) and SEBS type (high and low molecular weight). The specimens were characterized according to their morphology, crystallinity, thermomechanical and mechanical properties. Samples processed in a screw with more kneading zones had a lower modulus value. Compression molded specimens had lower mechanical performance than injected samples. Samples prepared with low molecular weight SEBS presented a loss of mechanical properties. It was possible to correlate processing form with all the properties evaluated. The analyzed variables influenced the morphology, crystallinity and thermomechanical properties, but had low influence on the tensile properties.     

Rheological properties,tensile properties,and morphology of PP/EPDM/lonomer ternary blends

The rheological and tensile properties and the morphology of polypropylene (PP)/ethylenepropylene-diene terpolymer(EPDM)/ionomer ternary blends were investigated, using a rheometric dynamic spectrometer (RDS), a dynamic mechanical thermal analyzer (DMTA), a tensile tester, and a scanning electron microscope (SEM). Two kinds of poly(ethylene-co-methacrylic acid) (EMA) ionomers, neutralized with different metal ions (Na⁺ and Zn⁺⁺), were used. Blends were melt-mixed, using a laboratory internal mixer at 190°C. The composition of PP and EPDM was fixed at 50/50 by wt % and the EMA ionomer contents were varied from 5 to 20 wt %, based on the total amount of PP and EPDM. It was found that the ternary blends, containing Na-neutralized ionomer, showed considerably different rheological properties and morphology as compared to the PP/EPDM binary blends, due to the compatibilizing effect of the ionomer for PP and EPDM, while the ternary blends, containing the Zn-neutralized ionomer, did not. The compatibilizing effect was most prominent at 5 wt % ionomer concentration. © 1994 John Wiley & Sons, Inc.     

SEBS在PP共混物中的研究进展

综述了氢化苯乙烯－丁二烯－苯乙烯嵌段共聚物作为塑料改性剂和共混相容剂，在聚丙烯及其共混物中对共混体系的屈服，冲击，断裂力学等性能的影响及研究进展。     

纳米CaCO3在SEBS／PP中的应用研究

以苯乙烯-乙烯-丁二烯-苯乙烯嵌段共聚物（SEBS）和聚丙烯（PP）为基体树脂,以纳米碳酸钙和普通重质碳酸钙为填充材料,在一定的工艺条件下用开炼机混炼。通过对SEBS／PP力学性能的测试及扫描电镜的比较,研究了纳米碳酸钙和普通重质碳酸钙对SEBS／PP共混料性能的影响及在基体中的分散情况。实验结果表明,纳米碳酸钙对共混物起到补强作用且其在共混物体系内呈纳米分散,随着纳米碳酸钙用量的增加,材料性能呈上升趋势,至12份时达到最大值。     

SEBS/PP/OMMT纳米复合材料的制备及性能

通过对蒙脱土的有机化处理,利用熔融插层的方法制备了苯乙烯-乙烯/丁烯-苯乙烯三嵌段聚合物(SEBS)/聚丙烯(PP)/有机蒙脱土(OMMT)纳米复合材料,对其结构、热性能及力学性能进行了研究.结果表明,少量有机化蒙脱土能够大幅度提高SEBS中聚苯乙烯嵌段的玻璃化转变温度,而对材料的力学性能影响很小.     

Dynamic mechanical and impact properties of PP/SEBS blend

Studies on impact behaviour of the blend of isotactic polypropylene (PP) with styrene-b-ethylene-co-butylene–b-styrene triblock copolymer (SEBS) in the composition range 0–25 wt % SEBS at three temperatures, viz., ambient, ?30°C, and ?190°C, are presented. Dynamic mechanical properties on a torsion pendulum in the temperature range ?100?100°C are also studied for this blend at various compositions. Scanning electron microscopic studies of the impact-fractured surfaces are presented to illustrate the differences in the mode of fracture at the three temperatures of impact tests. Choice of the three temperatures for impact tests was such that the effect of shear yielding mechanism of toughening of PP at ambient temperature remains suppressed at ?30°C, whereas at the lowest temperature (i.e., ?190°C) the elastomeric role of the inclusion SEBS is suppressed. The observed considerably large difference in impact toughening at ambient temperature and at ?;30°C seems not entirely accountable by the prevalence of shear yielding or crazing mechanisms in the respective temperature regions. A third mechanism, viz., viscoelastic energy dissipation, is invoked to account for the observed large difference of impact toughening at these two upper temperatures. Correlation of peak area of dynamic mechanical loss peaks occurring below the impact test temperature with the impact strength is also shown. This suggests greater significance of viscoelastic energy dissipation mechanism in the toughening of this blend at ambient temperature than at ?30°C.     

聚丙烯/含氟聚丙烯层状共混物的制备

采用熔融接枝技术制备含氟聚丙烯（FPP），然后将聚丙烯（PP）与FPP共混造粒制备PP／FPP共混物。用锥板流变仪分析PP和FPP的流变行为，探讨PP／FPP共混物层状形态形成的条件；用扫描电子显微镜、紫外光测试仪和万能材料试验机分析PP／FPP共混物层状形态、抗紫外光辐射性能和力学性能。结果表明，在200℃．剪切速率为125s^-1时，PP和FPP的流变曲线相交于一点，此条件有利于PP／FPP共混物形成层状形态。与纯PP相比，PP／FPP共混物的力学性能和抗紫外光透过能力明显提高。     

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     

Effect of reactive compatibilisation on the phase morphology and tensile properties of PA12/PP blends

Both uncompatibilized and compatibilized blends based on polyamide 12 (PA12) and isotactic polypropylene (PP) were prepared in a Brabender Plastograph®. The compatibiliser used was maleic anhydride functionalized polypropylene (PP‐g‐MA). Phase morphology of the blends was inspected in scanning electron microscope (SEM) on cryogenically fractured etched surfaces of the specimens. PA12/PP blends possessed a nonuniform and unstable morphology owing to the incompatibility between their constituents. Addition of compatibiliser improved the interfacial characteristics of the blends by retarding the rate of coalescence. So, the phase morphology became more fine, uniform, and stable. Tensile properties of both uncompatibilized and compatibilized blends were measured as a function of blend composition and compatibiliser concentration. Uncompatibilized blends displayed inferior mechanical properties to compatibilized ones; especially for those containing 40–60 wt % of PP. Reactive compatibilisation of blends was found to be efficient and improved the tensile strength of the blends considerably. Addition of PP‐g‐MA improved the interfacial adhesion, decreased the interfacial tension, and thereby, enhanced the tensile strength by 85%. Finally, various models were adopted to describe the tensile strength of the blends. The experimental data exhibited a reasonably good fit with Nielsen's first power law model. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

聚乳酸（PLA）／三醋酸甘油酯（TAc）的结晶性能研究

用三醋酸甘油酯（TAc）增塑聚乳酸（PLA）,研究了TAc对PLA在不同温度结晶时的结晶性能的影响。随着TAc的添加,PLA的结晶度与其球晶生长速率逐渐增加,断裂伸长率增大,抗张强度降低。TAc的最佳添加量为25％。研究不同温度等温结晶时PLA/TAc的机械性能以及晶体形态的影响,发现结晶温度升高,PLA/TAc的球晶生长速率减小,抗张强度增大,断裂伸长率降低。     

E-MA-GMA增容PP/PC体系的形态与性能

采用直接混合法和分级注入法制备了乙烯-丙烯酸酯-甲基丙烯酸缩水甘油酯共聚物增容聚碳酸酯/聚丙烯共混物.比较了两种混合方法对增容体系形态和性能的影响.结果表明,相比直接混合法,利用分级注入法所得混合体系的拉伸断裂应变大幅提高,且共混体系中分散相粒子与基体问有更强的界面作用,分散相粒子尺寸明显变小.用裂纹扩展功(G1C)评...     

Structure and properties of PP/POE/HDPE blends

This work was aimed to counteract the effect of ethylene‐α‐olefin copolymers (POE) by reinforcing the polypropylene (PP)/POE blends with high density polyethylene (HDPE) particles and, thus, achieved a balance between toughness and strength for the PP/POE/HDPE blends. The results showed that addition of HDPE resulted in an increasing wide stress plateau and more ductile fracture behavior. With the increase of HDPE content, the elongation at break of the blends increased rapidly without obvious decrease of yield strength and Young's modulus, and the notched izod impact strength of the blends can reach as high as 63 kJ/m² at 20 wt % HDPE loading. The storage modulus of PP blends increased and the glass transition temperature of each component of the blends shifted close to each other when HDPE was added. The crystallization of HDPE phase led to an increase of the total crystallinity of the blend. With increasing HDPE content, the dispersed POE particle size was obviously decreased, and the interparticle distance was effectively reduced and the blend rearranged into much more and obvious core‐shell structure. The fracture surface also changed from irregular striation to the regularly distant striations, displaying much obvious character of tough fracture. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Mechanical properties of HDPE/(PEC/PS)/SEBS blends

Various amounts of a styrene-butadiene-based triblock copolymer (SEBS) was used to compatibilize immiscible blends of high density polyethylene (HDPE) and an amorphous glassy phase consisting of either pure polystyrene (PS) or a miscible blend of PS and a polyether copolymer (PEC). PEC is structurally similar to poly(2,6-dimethyl-1,4-phenylene oxide) (PPO). Mechanical properties were determined for blends fabricated by injection and compression molding. The inherently brittle two-phase HDPE/(PEC/PS) blends show significant increases in ductility and impact strength resulting from addition of SEBS. These improvements coincide with a slight loss in modulus and yield strength. If the amount of HDPE and SEBS is held constant, impact strength and ductility increase with the amount of PEC in the glassy phase. These trends evidently result from the added ductility of glassy phases containing PEC and perhaps from better interfacial adhesion in blends after adding SEBS. The latter stems from the thermodynamic miscibility between PEC and PS endblocks of SEBS which provide an enthalpic driving force for compatibilization. Differences between the properties of compression and injection-molded blends can be attributed to the degree of crystallinity and orientation induced during molding.     

PP/iPB共混物的性能

采用自制的不同熔体流动速率的全同聚1-丁烯(iPB)改性聚丙烯(PP),研究了共混物的力学性能、热性能和结晶性能.结果表明:随着w(iPB)的增加,共混物的冲击强度明显增大,韧性得到改善,而刚性有所下降,共混物的晶体明显细化.     

Comparison of mechanical properties of PP/SEBS blends at intermediate and high strain rates with SiO2 nanoparticles vs. CaCO3 fillers

The present article focuses on the effect of two types of inorganic fillers (SiO₂ and CaCO₃) on the mechanical properties of PP/SEBS blend. The nominal particle diameters of SiO₂ and CaCO₃ are 7 nm and 1 μm, respectively. The studied blend ratios were PP/SEBS/SiO₂ (CaCO₃) = 75/22/3 and 73/21/6 vol %. The morphology of polymer blends was observed and the distributions of the SEBS, SiO₂, and CaCO₃ particles were analyzed by transmission electron microscopy (TEM). Tensile tests were conducted at nominal strain rates from 3 × 10^?1 to 10² s^?1. The apparent elastic modulus has the local strain‐rate dependency caused by SiO₂ nanoparticles around SEBS particles in the blend of PP/SEBS/SiO₂. The yield stress has weak dependency of morphology. The absorbed strain energy has strong dependency of the location of SiO₂ nanoparticle or CaCO₃ fillers and SEBS particle in the morphology. It is considered that such morphology, in which inorganic nanoparticles are located around SEBS particles, can prevent the brittle fracture while the increased local strain rate can enhance the apparent elastic modulus of the blend at the high strain rate. On the basis of the results of this study, the location and size of inorganic nanoparticles are the most important parameters to increase the elastic modulus without decreasing the material ductility of the blend at both low and high strain rates. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Morphology and properties of PP/EPDM binary blends and PP/EPDM/nano‐CaCO3 ternary blends

In this article, the morphology, crystallization, and rheological behaviors of polypropylene (PP)/ethylene‐propylene‐diene terpolymer (EPDM) binary blend and PP/EPDM/calcium carbonate nanoparticles (nano‐CaCO₃) ternary blend were investigated. Two processing methods, i.e., direct extrusion and two‐step extrusion, were employed to prepare the PP/EPDM/CaCO₃ blend. The influence of EPDM and nano‐CaCO₃ respectively on phase morphology and properties of PP/EPDM blend and PP/EPDM/CaCO₃ blend were characterized by scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and dynamic rheometer. The crystallinity and crystallization temperature of PP/EPDM blend were improved in comparison to pure PP due to addition of EPDM, but kept invariable with the increased EPDM loading. As the EPDM content was increased, the mobility of PP molecular chains was weakened. Compared with direct extruded blend, less and finer nano‐CaCO₃ was dispersed in matrix of two‐step extruded blend. Accordingly, the increased nano‐CaCO₃ in matrix gave rise to a weaker increment in crystallinity and crystallization temperature of two‐step extruded blend, and a later platform of tanδ curve. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

PP／PS／SEBS三元共混物的研究

以PS、SEBS为改性剂对PP进行改性。加入PS,体系的强度和刚度得到提高,断裂伸长率和冲击性能下降,对其改变的原因采用SEM进行了结构分析;SEBS是PS的良好相容剂,也是PP很好的增韧剂。同时使用PS和SEBS,体系拉伸强度为24．4MPa,弯曲模量810．6MPa,冲击强度82．0J／m,熔体流动速率12．7g/10min。