首页 | 官方网站   微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 296 毫秒
1.
In this article, the dynamic vulcanization process was applied to polypropylene (PP)/Novolac blends compatibilized with maleic anhydride‐grafted PP (MAH‐g‐PP). The influences of dynamic cure, content of MAH‐g‐PP, Novolac, and curing agent on mechanical properties of the PP/Novolac blends were investigated. The results showed that the dynamically cured PP/MAH‐g‐PP/Novolac blend had the best mechanical properties among all PP/Novolac blends. The dynamic cure of Novolac improved the modulus and stiffness of the PP/Novolac blends. The addition of MAH‐g‐PP into dynamically cured PP/Novolac blend further enhanced the mechanical properties. With increasing Novolac content, tensile strength, flexural modulus, and flexural strength increased significantly, while the elongation at break dramatically deceased. Those blends with hexamethylenetetramine (HMTA) as a curing agent had good mechanical properties at HMTA content of 10 wt %. Scanning electron microscopy (SEM) analysis showed that dynamically cured PP/MAH‐g‐PP/Novolac blends had finer domains than the PP/MAH‐g‐PP/Novolac blends. Thermogravimetric analysis (TGA) results indicated that the incorporation of Novolac into PP could improve the thermal stability of PP. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007  相似文献   

2.
Dynamic vulcanization was successfully applied to epoxy resin reinforced polypropylene (PP)/ethylene‐octene copolymer (POE) blends, and the effects of different compatibilizers on the morphology and properties of dynamically cured PP/POE/epoxy blends were studied. The results show that dynamically cured PP/POE/epoxy blends compatibilized with maleic anhydride‐grafted polypropylene (MAH‐g‐PP) have a three‐phase structure consisting of POE and epoxy particles dispersed in the PP continuous phase, and these blends had improved tensile strength and flexural modulus. While using maleic anhydride‐grafted POE (MAH‐g‐POE) as a compatibilizer, the structure of the core‐shell complex phase and the PP continuous phase showed that epoxy particles could be embedded in MAH‐g‐POE in the blends, and gave rise to an increase in impact strength, while retaining a certain strength and modulus. DSC analysis showed that the epoxy particles in the blends compatibilized with MAH‐g‐PP were more efficient nucleating agents for PP than they were in the blends compatibilized with MAH‐g‐POE. WAXD analysis shows that compatibilization do not disturb the crystalline structure of PP in the blends. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012  相似文献   

3.
利用差示扫描量热方法研究了马来酸配接枝聚丙烯(PP-g-MAH)增容动态固化聚丙烯(PP) /环氧树脂(EP)共混物非等温结晶过程,并运用(hawa方程和Kissinger方程进行相关数据处理,同时研究共混物晶体结构。结果表明,动态固化PP/PP-g-MAH/EP共混物中EP颗粒可明显促进PP的结晶,(hawa方程可以有效处理PP和共混物非等温结晶过程,在相同温度下共混物中PP的结晶速率常数[K}(T)〕大于纯PP的[K} (T)]。依据Kissinger方程,共混物中PP的结晶活化能(4E)明显小于纯PP的,在EP含量为20份(质量份数,下同)时,4E有一极小值。偏光显微镜显示PP的晶粒是典型的球形结构,其晶粒尺寸明显大于动态固化PP /PP-g-MAH/EP共混物中PP晶粒尺寸。  相似文献   

4.
The dynamic vulcanization process, usually used for the preparation of thermoplastic elastomers, was used to prepare polypropylene (PP)/epoxy blends. The blends had crosslinked epoxy resin particles finely dispersed in the PP matrix, and they were called dynamically cured PP/epoxy blends. Maleic anhydride grafted polypropylene (MAH‐g‐PP) was used as a compatibilizer. The effects of the reactive compatibilization and dynamic cure were studied with rheometry, capillary rheometry, and scanning electron microscopy (SEM). The crystallization behavior and mechanical properties of PP/epoxy, PP/MAH‐g‐PP/epoxy, and dynamically cured PP/epoxy blends were also investigated. The increase in the torque at equilibrium for the PP/MAH‐g‐PP/epoxy blends indicated the reaction between maleic anhydride groups of MAH‐g‐PP and the epoxy resin. The torque at equilibrium of the dynamically cured PP/epoxy blends increased with increasing epoxy resin content. Capillary rheological measurements also showed that the addition of MAH‐g‐PP or an increasing epoxy resin content increased the viscosity of PP/epoxy blends. SEM micrographs indicated that the PP/epoxy blends compatibilized with PP/MAH‐g‐PP had finer domains and more obscure boundaries than the PP/epoxy blends. A shift of the crystallization peak to a higher temperature for all the PP/epoxy blends indicated that uncured and cured epoxy resin particles in the blends could act as effective nucleating agents. The spherulites of pure PP were larger than those of PP in the PP/epoxy, PP/MAH‐g‐PP/epoxy, and dynamically cured PP/epoxy blends, as measured by polarized optical microscopy. The dynamically cured PP/epoxy blends had better mechanical properties than the PP/epoxy and PP/MAH‐g‐PP/epoxy blends. With increasing epoxy resin content, the flexural modulus of all the blends increased significantly, and the impact strength and tensile strength increased slightly, whereas the elongation at break decreased dramatically. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1437–1448, 2004  相似文献   

5.
The melting behavior, nonisothermal crystallization behavior, and morphology of pure polypropylene (PP) and its blends were investigated by differential scanning calorimetry and polarized optical microscopy. The nonisothermal crystallization kinetics was analyzed using the Avrami equation modified by Jeziorny and the equation combining the Avrami and Ozawa method. The surface fold free energy and the effective activation energy for both PP and its blends were obtained by Hoffman‐Lauritzen theory and Vyazovkin's approach, respectively. The results showed that the presence of nylon 11 hindered the mobility of PP chains but accelerated the overall crystallization rate. The POM observation confirmed that the addition of nylon 11 decreased the spherulites size of PP matrix. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008  相似文献   

6.
Polypropylene/polypropylene‐grafted‐maleic anhydride/glass fiber reinforced polyamide 66 (PP/PP‐g‐MAH/GFR PA 66) blends‐composites with and without the addition of polypropylene‐grafted‐maleic anhydride (PP‐g‐MAH) were prepared in a twin screw extruder. The effect of the compatibilizer on the thermal properties and crystallization behavior was determined using differential scanning calorimetry analysis. The hold time was set to be equal to 5 min at 290°C. These conditions are necessary to eliminate the thermomechanical history in the molten state. The crystallization under nonisothermal conditions and the plot of Continuous‐Cooling‐Transformation of relative crystallinity diagrams of both PP and PA 66 components proves that PP is significantly affected by the presence of PP‐g‐MAH. From the results it is found that an abrupt change is observed at 2.5 wt % of PP‐g‐MAH as a compatibilizer and then levels off. In these blends, concurrent crystallization behavior was not observed for GFR PA66. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1620–1626, 2007  相似文献   

7.
Qing-Xin Zhang  Jian-Bin Song  Zhi-Shen Mo 《Polymer》2005,46(25):11820-11828
Polypropylene (PP) was blended with polyoxyethylene nonylphenol (PN) in a twin-screw extruder and injection moulded. The dynamic mechanical properties of PP/PN blends were characterized by dynamic mechanical analyser (DMA). The glass transition temperature (Tg) of PP showed a slight decrease with incorporation of PN. Differential scanning calorimetry (DSC), wide angle X-ray diffraction (WAXD) and polarized optical microscopy (POM) were employed to investigate the effects of PN on crystallization of PP. In a study of nonisothermal crystallization of PP and PP/PN blends, crystallization parameter analysis showed the addition of PN reduced the peak temperature of crystallization. β-form crystals of PP coexisted with α-form crystals in PP/PN blends, and oriented on the surface layer of injection moulded bar as revealed by WAXD. The degree of orientation was determined using Hermans orientation function. The thermal stability of β-form crystals was evaluated using high temperature WAXD and POM.  相似文献   

8.
Abstract

A new method concerning the simultaneous reinforcing and toughening of polypropylene (PP) is reported. Dynamic cure of the epoxy resin with 2-ethylene-4-methane-imidazole was successfully applied in the PP/maleic anhydride grafted styrene–ethylene–butylene–styrene (MAH-g-SEBS) triblock co-polymer, and the obtained blends were named as dynamically cured PP/MAH-g-SEBS/epoxy blends. The stiffness and toughness of the blends are in a good balance, and the smaller size of the epoxy particle in the PP/MAH-g-SEBS/epoxy blends shows that MAH-g-SEBS was also used as a compatibiliser. The structure of the dynamically cured PP/MAH-g-SEBS/epoxy blends is the embedding of the epoxy particles by MAH-g-SEBS. The cured epoxy particles as organic filler increase the stiffness of the PP/MAH-g-SEBS blends, and the improvement in the toughness is attributed to the embedded structure. The tensile strength and flexural modulus of the blends increase with increasing epoxy resin content, and the impact strength reaches a maximum of 342 J m?1 at the epoxy resin content of 10wt-%. Differential scanning calorimetry analysis shows that the epoxy particles in the dynamically cured PP/MAH-g-SEBS/epoxy blends could have contained embedded MAH-g-SEBS, decreasing the nucleating effect of the epoxy resin. Wide angle X-ray diffraction analysis shows that the dynamical cure and compatibilisation do not disturb the crystalline structure of PP in the blends.  相似文献   

9.
A maleic anhydride grafted thermoplastic elastomer (TPEg) was prepared. The effect of the TPEg on the morphology and performance of polypropylene (PP)/polyamide 6 (PA‐6) blends was studied. The final properties of the blends were tuned through variations in the TPEg/PA‐6 ratios and TPEg and PA‐6 percentages in the blends. Scanning electron micrographs showed that the TPEg greatly improved the homogeneity of the blends, and this led to better mechanical performance. The nonisothermal crystallization behaviors of PP and PA‐6 in the blends, revealed by differential scanning calorimetry, were different from those of pure PP and PA‐6. The crystallization temperature and rate of PP were promoted by the PA‐6 component because of its nucleating effect, whereas stepwise crystallization was detected for PA‐6 in the PP/PA‐6 blends when the TPEg was added. On the basis of these observations, a schematic model was proposed for these blends. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1806–1815, 2004  相似文献   

10.
A method concerning with the simultaneous reinforcing and toughening of polypropylene (PP) was reported. Dynamical cure of the epoxy resin with 2‐ethylene‐4‐methane‐imidazole (EMI‐2,4) was successfully applied in the PP/maleic anhydride‐grafted ethylene‐vinyl acetate copolymer (MAH‐g‐EVA), and the obtained blends named as dynamically cured PP/MAH‐g‐EVA/epoxy blends. The stiffness and toughness of the blends are in a good balance, and the smaller size of epoxy particle in the PP/MAH‐g‐EVA/epoxy blends shows that MAH‐g‐EVA was also used as a compatibilizer. The structure of the dynamically cured PP/MAH‐g‐EVA/epoxy blends is the embedding of the epoxy particles by the MAH‐g‐EVA. The cured epoxy particles as organic filler increases the stiffness of the PP/MAH‐g‐EVA blends, and the improvement in the toughness is attributed to the embedded structure. The tensile strength and flexural modulus of the blends increase with increasing the epoxy resin content, and the impact strength reaches a maximum of 258 J/m at the epoxy resin content of 10 wt %. DSC analysis shows that the epoxy particles in the dynamically cured PP/MAH‐g‐EVA/epoxy blends could have contained embedded MAH‐g‐EVA, decreasing the nucleating effect of the epoxy resin. Thermogravimetric results show the addition of epoxy resin could improve the thermal stability of PP, the dynamically cured PP/MAH‐g‐EVA/epoxy stability compared with the pure PP. Wide‐angle x‐ray diffraction analysis shows that the dynamical cure and compatibilization do not disturb the crystalline structure of PP in the blends. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009  相似文献   

11.
PP/纳米TiO2复合材料的晶体形貌和非等温结晶行为   总被引:2,自引:0,他引:2  
用熔融共混法制备了聚丙烯(PP)/纳米TiO2复合材料,用透射电子显微镜、偏光显微镜、差示扫描量热仪和广角X射线衍射仪对其纳米粒子分散性、晶体形貌和非等温结晶行为进行了研究。结果表明,纳米TiO2以纳米级尺寸均匀分散于PP基体中;130 ℃冷却和室温冷却时,PP/纳米TiO2复合材料的晶粒比纯PP的细,并且随着纳米TiO2含量的增加,PP/纳米TiO2复合材料的晶粒尺寸先减小后增大,纳米TiO2含量为2 %(质量分数,下同)时晶粒最细;纳米TiO2对PP结晶具有加速作用;复合材料的结晶活化能高于纯PP的,并且纳米TiO2含量多且均匀时复合材料结晶活化能高;纳米TiO2含量较少时可诱导较多的β晶生成,当纳米TiO2含量为1 %时,复合材料中β晶含量达到25.2 %。  相似文献   

12.
Moderate cross‐linked blend (LLDPE‐PP) of linear low‐density polyethylene (LLDPE) and polypropylene (PP) with benzoyl peroxide (BPO) were prepared by the reactive melt mixing in HAAKE mixer. Effect of LLDPE‐PP as compatibilizer on the morphology, crystallization behavior and mechanical properties of LLDPE/PP (87/13) blends were studied using scanning electron microscopy (SEM), polarized optical microscopy (POM), wide‐angle X‐ray diffraction (WAXD), differential scanning calorimetry (DSC) and mechanical testing machines. The results showed that LLDPE‐PP not only improved the interfacial adhesion between the LLDPE and PP but also acted as selective nucleating agent for crystal modification of PP. In the blends, the sizes of LLDPE and PP spherulites became smaller, and their melting enthalpies reduced in the presence of LLDPE‐PP. Furthermore, the mechanical properties of LLDPE/PP blends were improved with the addition of LLDPE‐PP, and when the concentration of LLDPE‐PP was 2 phr, the ternary blend had the best mechanical properties. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011  相似文献   

13.
The effects of the glass‐bead content and size on the nonisothermal crystallization behavior of polypropylene (PP)/glass‐bead blends were studied with differential scanning calorimetry. The degree of crystallinity decreased with the addition of glass bead, and the crystallization temperature of the blends was marginally higher than that of pure PP at various cooling rates. Furthermore, the half‐time for crystallization decreased with an increase in the glass‐bead content or particle size, implying the nucleating role of the glass beads. The nonisothermal crystallization data were analyzed with the methods of Avrami, Ozawa, and Mo. The validity of various kinetic models for the nonisothermal crystallization process of PP/glass‐bead blends was examined. The approach developed by Mo successfully described the nonisothermal crystallization behavior of PP and PP/glass‐bead blends. Finally, the activation energy for the nonisothermal crystallization of pure PP and PP/glass‐bead blends based on the Kissinger method was evaluated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2026–2033, 2006  相似文献   

14.
The mechanical properties and crystal morphological structures of dynamically photocrosslinked polypropylene (PP)/ethylene‐propylene‐diene terpolymer (EPDM) blends have been studied by mechanical tests, wide‐angle X‐ray diffraction (WAXD), scanning electron microscopy (SEM), and differential scanning calorimetry (DSC). Dynamically photocrosslinking of PP/EPDM blends can improve the mechanical propertiess considerably, especially the notched Izod impact strength at low temperature. Data obtained from mechanical tests show that the notched Izod impact strength of a dynamically photocrosslinked sample with 30% EPDM at ?20°C is about six times that of an uncrosslinked sample with the same EPDM component. The results from the WAXD, SEM, and DSC measurements reveal the enhanced mechanism of impact strength for the dynamically photocrosslinked PP/EPDM blends as follows: (i) the β‐type crystal structure of PP is formed and the interplanar distance of β‐type crystal increases slightly with an increase in the EPDM component; (ii) the droplet size of the EPDM phase in the photocrosslinked PP/EPDM blends is obviously reduced and the droplet number is increased with an increase in the EPDM component during the dynamical photocrosslinking process; (iii) the graft copolymer of PP‐g‐EPDM is formed at the interface between PP and EPDM components. All the above changes from the crystal morphological structures are favorable for increasing the compatibility and enhancing the toughness of PP/EPDM blends at low temperatures.  相似文献   

15.
Summary A melt-grafting approach was employed to prepare a novel functional polypropylene(FPP)—amino-terminated polyurethane grafted polypropylene (PP-g-ATPU). The crystallization behaviors of PP and PP/FPP blends were characterized using differential scanning calorimetry (DSC), wide angle X-ray scattering (WAXS) and polarized optical microscopy (POM). The effects of FPP composition on crystallization behavior, crystal transformation, and morphology of PP/FPP crystalline were investigated. The results showed that at a low dosage (<2.0 wt%) ATPU acted as a heterogeneous nucleation agent during the crystallization of PP/FPP blends. However, when the content of ATPU reached 2.0 wt% or higher, ATPU deteriorated the crystallization of PP or PP/FPP blends. The crystallite size decreased and the number of crystallites increased as the ATPU content increased. The Avrami analysis was adopted to describe the isothermal crystallization process. The difference in the exponent n between PP and PP/FPP suggested that the isothermal crystallization kinetics of PP/FPP blends followed a three-dimensional growth via heterogeneous nucleation. In terms of the half-time of the crystallization, t1/2, the crystallization rate of functional PP blends was faster than that of PP homopolymer at a given crystallization temperature.  相似文献   

16.
The melting, crystallization behaviors, and nonisothermal crystallization kinetics of the ternary blends composed of poly(ethylene terephthalate), poly(trimethylene terephthalate) (PTT) and poly(buthylene terephthalate) (PBT) were studied with differential scanning calorimeter (DSC). PBT content in all ternary blends was settled invariably to be one‐third, which improved the melt‐crystallization temperature of the ternary blends. All of the blend compositions in amorphous state were miscible as evidenced by a single, composition‐dependent glass transition temperature (Tg) observed in DSC curves. DSC melting thermograms of different blends showed different multiple melting and crystallization peaks because of their various polymer contents. During melt‐crystallization process, three components in blends crystallized simultaneously to form mixed crystals or separated crystals depending upon their content ratio. The Avrami equation modified by Jeziorny and the Ozawa theory were employed to describe the nonisothermal crystallization process of two selected ternary blends. The results spoke that the Avrami equation was successful in describing the nonisothermal crystallization process of the ternary blends. The values of the t1/2 and the parameters Zc showed that the crystallization rate of the ternary blends with more poly(ethylene terephthalate) content was faster than that with the lesser one at a given cooling rate. The crystal morphology of the five ternary blends investigated by polarized optical microscopy (POM) showed different size and distortional Maltese crosses or light spots when the PTT or poly(ethylene terephthalate) component varied, suggesting that the more the PTT content, the larger crystallites formed in ternary blends. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007  相似文献   

17.
The crystallization behaviors, non-isothermal crystallization kinetics, and the morphology of poly(trimethylene terephthalate)/Polypropylene (PTT/PP) blends using a maleic anhydride grafted polypropylene (PP-g-MAH) as a compatibilizer were investigated by differential scanning calorimeter (DSC) and scanning electron microscope (SEM), respectively. The results suggested that the blends exhibited different crystallization and melting behaviors due to different content of PP-g-MAH. All of the DSC curves of the blends exhibited two exothermic peaks and endothermic peaks. The commonly used Avrami equation modified by Jeziorny, Ozawa theory and the method developed by Mo were used, respectively, to fit the primary stage of non-isothermal crystallization process. The results suggested that the crystallization rate of PTT component was increased, whereas, that of PP component was retarded with the introduction of PP-g-MAH. The effective activation energy was calculated by differential iso-conversional method developed by Vyazovkin. The SEM result suggested that the introduction of PP-g-MAH greatly improved the compatibility between PTT and PP, and decreased the size of dispersed particles.  相似文献   

18.
A highly novel nano‐CaCO3 supported β‐nucleating agent was employed to prepare β‐nucleated isotactic polypropylene (iPP) blend with polyamide (PA) 66, β‐nucleated iPP/PA66 blend, as well as its compatibilized version with maleic anhydride grafted PP (PP‐g‐MA), maleic anhydride grafted polyethylene‐octene (POE‐g‐MA), and polyethylene‐vinyl acetate (EVA‐g‐MA), respectively. Nonisothermal crystallization behavior and melting characteristics of β‐nucleated iPP and its blends were investigated by differential scanning calorimeter and wide angle X‐ray diffraction. Experimental results indicated that the crystallization temperature (T) of PP shifts to high temperature in the non‐nucleated PP/PA66 blends because of the α‐nucleating effect of PA66. T of PP and the β‐crystal content (Kβ) in β‐nucleated iPP/PA66 blends not only depended on the PA66 content, but also on the compatibilizer type. Addition of PP‐g‐MA and POE‐g‐MA into β‐nucleated iPP/PA66 blends increased the β‐crystal content; however, EVA‐g‐MA is not benefit for the formation of β‐crystal in the compatibilized β‐nucleated iPP/PA66 blend. It can be relative to the different interfacial interactions between PP and compatibilizers. The nonisothermal crystallization kinetics of PP in the blends was evaluated by Mo's method. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011  相似文献   

19.
The nonisothermal crystallization, melting behavior, and morphology of isotactic polypropylene (PP)/linear bimodal polyethylene (LBPE) blends were studied with differential scanning calorimetry, scanning electron microscopy, and polarized optical microscopy. The results showed that PP and LBPE were miscible to a certain extent, and there was no obvious phase separation in the blends. The modified Avrami analysis, Ozawa equation, and Mo method were used to analyze the nonisothermal crystallization kinetics of the blends. The values of the Avrami exponent indicated that the crystallization nucleation of the blends was homogeneous, the growth of spherulites was three‐dimensional, and the crystallization mechanism of PP was not affected much by LBPE. The crystallization activation energy was estimated by the Kissinger method. The results obtained with the modified Avrami analysis, Mo method, and Kissinger method agreed well. The addition of a minor LBPE phase favored an increase in the overall crystallization rate of PP, showing some dilution effect of LBPE on PP. The PP spherulites decreased obviously with increasing content of LBPE. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008  相似文献   

20.
The effect of crystallization on the structure and morphology of maleic anhydride grafted polypropylene (PP‐MA)/clay (montmorillonite) nanocomposites (PPCNs) is presented. Wide‐angle X‐ray diffraction (WAXD) measurements of PPCNs crystallized at different temperatures show that the extent of intercalation increases with the crystallization temperature. The enhancement of intercalation occurs with lower clay content PPCNs, and maximum intercalation takes place for 4 wt% clay content. The mechanism of intercalation has been proposed through crystallization. Excess γ‐form of the crystallite of PP‐MA appears in presence of clay, possibly because of the confinement of the polymer chain between the clay particles. WAXD data also reveals that d‐spacing increases gradually with clay content. The decrease of spherulitic size is observed with increasing clay content, which indicates that clay particles act as nucleating agents. Lamellar textures have been explored by using small angle X‐ray scattering (SAXS) and transmission electron microscopy (TEM), which exhibit that both the lamellar thickness and long period of the PPCNs are higher than those of PP‐MA.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司    京ICP备09084417号-23

京公网安备 11010802026262号