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采用直接离子交换反应制备直接改性水滑石(DLDH)和超声离子交换反应制备超声改性水滑石(CLDH)。运用差示扫描量热(DSC)仪、偏光显微镜(PLM)分析纯聚丙烯(PP)、PP/未改性水滑石(LDH),PP/DLDH,PP/CLDH复合材料的等温结晶行为和结晶形态,并计算其等温结晶动力学。结晶动力学结果表明:相较于纯PP,三种改性PP复合材料的半结晶时间及最大结晶时间缩短,半结晶速率提高,说明LDH,DLDH及CLDH对PP具有异相成核作用。其中在120℃等温结晶时,添加CLDH的改性PP复合材料的结晶速率常数由纯PP的3.344 2min~(-1)提高至36.904 4min~(-1),半结晶时间由纯PP的0.53min缩短至0.20min,最大结晶时间由纯PP的0.50min降低至0.18min,而半结晶速率由纯PP的1.89min~(-1)增加至5.09min~(-1)。对改性PP复合材料晶体形貌的PLM观察说明,DLDH和CLDH均能细化PP球晶尺寸,增加晶粒数量,其中CLDH对PP结晶性能的提升最为显著。 相似文献
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为了研究水滑石(LDH)与β成核剂组成的复配成核剂对等规聚丙烯(PP)的成核效果,采用差示扫描量热(DSC)仪研究了β成核剂和LDH/β改性等规PP的等温结晶动力学。实验结果表明,在等温结晶温度(120,122,124,126,128℃)下,复配成核剂使等规PP达到最大结晶速率时的时间和半结晶期缩短了83%~95%,大幅度提高了等规PP的动力学结晶速率常数(例如当等温结晶温度为120℃时,使等规PP的动力学结晶速率常数从0.35 min-1提高到57.74 min-1)。在等温结晶过程中得到的Avrami指数n在2.28~3.41之间,在等温结晶条件下,纯等规PP及改性等规PP的晶体可能是二维盘状生长和球晶三维生长。复配成核剂在等规PP中起到了良好的异相成核作用,显著地提高了等规PP的结晶速率。 相似文献
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PP/PET/POE-g-MAH共混合金的等温结晶动力学特性 总被引:1,自引:0,他引:1
应用差示扫描量热法(DSC),研究了加入不同份数增容剂POE-g-MAH的PP/PET共混合金及纯PP的等温结晶行为,采用Avrami方程处理等温结晶过程,计算结晶动力学参数。结果表明,随着结晶温度的升高各体系的结晶速率下降,结晶速率常数K、n降低,半结晶时间t1/2延长。同一温度下PET有明显的异相成核作用,提高了基体的结晶速率;POE-g-MAH的加入降低了基体的结晶速率,并且随着增容剂含量的增加,基体的结晶速率逐渐下降。纯PP的等温结晶过程具有异相成核与均相成核的机理,共混合金的等温结晶过程属于异相成核机理。 相似文献
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滑石粉、碳酸钙填充聚丙烯复合材料等温结晶行为的对比研究 总被引:3,自引:0,他引:3
邹燕;纪彬彬;温变英 《中国塑料》2010,24(2):26-29
用熔融共混法分别制备了聚丙烯(PP)/滑石粉、PP/碳酸钙(CaCO3)复合材料,用差示扫描量热法(DSC)考察了PP及其复合材料的等温结晶过程,并用Avrami方程对纯PP及PP/滑石粉、PP/CaCO3复合材料的等温结晶动力学行为进行了分析。结果表明,PP、PP/滑石粉及PP/CaCO3复合材料的Avrami指数均小于2.3,存在均相成核和异相成核双重成核机理,且其结晶速率常数和结晶速率均随着结晶温度的升高而减小;在该体系中,滑石粉对基体PP有明显的异相成核作用,使PP的结晶速率加快、结晶时间缩短;而CaCO3则没有明显的异相成核作用。 相似文献
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《塑料工业》2017,(9)
利用差示扫描量热仪(DSC)研究了热还原氧化石墨烯(TRG)对聚丙烯/乙烯-辛烯无规共聚物(PP/POE)等温结晶的影响,并用Avrami方程分析了PP/POE和加入石墨烯的PP/POE/TRG两个体系的结晶动力学。结果表明,Avrami指数n在这两个体系中的数值接近,在结晶温度升高时两个体系的半结晶时间会相应增大,其中PP/POE/TRG复合体系的半结晶时间比PP/POE明显减小,结晶速率更大,表明加入的石墨烯具有较好的异相成核作用。此外,PP/POE/TRG复合体系中PP的相对结晶度比在PP/POE中增大,结晶温度对PP/POE/TRG复合体系熔融温度的影响较小。 相似文献
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松香型成核剂成核聚丙烯的非等温结晶动力学研究 总被引:2,自引:0,他引:2
采用 DSC 法研究了聚丙烯(PP)和松香型成核剂成核 PP 在不同的降温速率下的非等温结晶动力学。采用修正的 Avrami 方程对 DSC 的测试结果进行了分析。结果表明,松香型成核透明剂和分散剂能显著提高 PP 的结晶温度,用 Jeziorny 法来处理松香型成核 PP 的非结晶等温结晶行为是较为吻合的。加入松香型成核透明剂和分散剂后,PP 的半结晶时间减少,结晶动力学常数 Zc 增加,结晶速率增加;同一降温速率,松香型成核透明剂和分散剂成核PP 的 n 值较纯 PP 减少,说明结晶成核方式发生了改变。 相似文献
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用超重力法制备的纳米CaCO3和PP熔融共混制备了PP/CaCO3复合材料,并对PP/CaCO3复合材料的结晶行为进行了详细研究。差示扫描量热分析表明,纳米CaCO3粒子的加入加快了PP的结晶速率,缩短了半结晶时间,130℃时含15份纳米CaCO3的PP/CaCO3复合材料的半结晶时间比纯PP的减少了8.92 min;结晶度有轻微下降,结晶温度为126.5 ℃时纯PP的结晶度为44.33 %,含15份纳米CaCO3的PP/CaCO3复合材料的结晶度为35.9 %。动力学研究数据表明,等温结晶过程符合Avrami方程,PP/CaCO3的n和k值都大于纯PP的;利用偏光显微镜观察了PP/CaCO3复合材料的结晶形貌及结晶生长过程,纳米CaCO3粒子的加入使球晶数量明显增多,意味着CaCO3起到了结晶成核剂的作用。 相似文献
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田瑶珠;王松;秦军;罗筑;于杰 《中国塑料》2010,24(12):98-101
用差式扫描量热仪和偏光显微镜研究了分散剂对聚丙烯(PP)和松香成核PP的非等温结晶行为,并比较了它们的透明性能。结果表明,不同的分散剂对PP和松香成核PP的结晶行为影响不一样,分散剂A和分散剂C能提高松香成核PP的结晶温度、结晶速率和结晶初始速率,能显著降低其球晶尺寸提高其透明性;而分散剂B不能提高松香成核PP的结晶速率和结晶初始速率,不能降低其球晶尺寸,对松香成核PP的透明性提高没有作用。 相似文献
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Effects of halloysite nanotubes on kinetics and activation energy of non-isothermal crystallization of polypropylene 总被引:1,自引:1,他引:0
Mingliang Du Baochun Guo Jingjing Wan Quliang Zou Demin Jia 《Journal of Polymer Research》2010,17(1):109-118
Halloysite nanotubes (HNTs), a kind of naturally occurring silicates possessing typical fibular structure, were introduced
to fabricate polypropylene (PP)/HNTs nanocomposites. The non-isothermal crystallization behaviors were investigated by differential
scanning calorimetry (DSC) method according to different treatments. The results suggest, with the inclusion of HNTs in PP
matrix, the nanocomposites crystallize at higher temperature regime, which are correlated with the heterogeneous nucleating
effects of HNTs during the crystallization process of PP. The kinetics studies of crystallization show that PP nanocomposites
possess faster crystallization process and higher activation energy due to the nucleating effect and hindrance effect of HNTs
to the motion of PP chains. The polarized light microscopy (PLM) observations further show that HNTs serve as nucleation sites
and accelerate the crystallization process. 相似文献
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In this paper, the crystallization characteristics of polypropylene and low ethylene content polypropylene copolymers with and without nucleating agents were studied by differential scanning calorimetry (DSC) and polarized light microscopy (PLM). In order to determine the nonisothermal crystallization rate of these materials, a new estimation method was introduced. Comparing with the crystallization rate coefficient (CRC), which was proposed by Khanna, we found the new approach is more reasonable. From the analysis of results of DSC and PLM, it can be concluded that nucleating agent is more efficient than it is in PP homopolymer. © 1994 John Wiley & Sons, Inc. 相似文献
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The non‐isothermal crystallization behavior, the crystallization kinetics, the crystallization activation energy and the morphology of isotactic polypropylene (iPP) with varying content of β‐nucleating agent were investigated using differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). The DSC results showed that the Avrami equation modified by Jeziorny and a method developed by Mo and co‐workers could be successfully used to describe the non‐isothermal crystallization process of the nucleated iPPs. The values of n showed that the non‐isothermal crystallization of α‐ and β‐nucleated iPPs corresponded to a tridimensional growth with homogeneous and heterogeneous nucleation, respectively. The values of crystallization rate constant showed that the rate of crystallization decreased for iPPs with the addition of β‐nucleating agent. The crystallization activation energy increased with a small amount (less than 0.1 wt%) of β‐nucleating agent and decreased with higher concentration (more than 0.1 wt%). The changes of crystallization rate, crystallization time and crystallization activation energy of iPPs with varying contents of β‐nucleating agent were mainly determined by the ratio of the content of α‐ and β‐phase in iPP (α‐PP and β‐PP) from the DSC investigation, and the large size and many intercrossing lamellae between boundaries of β‐spherulites for iPPs with small amounts of β‐nucleating agent and the small size and few intercrossing bands among the boundaries of β‐spherulites for iPPs with large amounts of β‐nucleating agent from the SEM examination. Copyright © 2010 Society of Chemical Industry 相似文献