滑石粉、碳酸钙填充聚丙烯复合材料等温结晶行为的研究

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。     

聚丙烯／滑石粉复合材料的等温结晶动力学

用差示扫描量热法(DSC)研究聚丙烯(PP)及PP／滑石粉复合材料的等温结晶过程。用Avrami方程全面分析PP／滑石粉的等温结晶动力学，并由此获得相关的动力学参数；用Kissinger方程研究滑石粉对PP／滑石粉复合材料结晶活化能的影响。研究表明：加入滑石粉后明显提高PP／滑石粉复合材料的结晶速率和结晶度；证明滑石粉能促进PP材料的结晶，并在PP结晶过程中起到异相成核作用。PP／滑石粉复合材料的等温结晶过程属于典型的异相成核机理。     

PP/稻壳粉复合材料的等温结晶行为研究

采用差示扫描量热法研究了聚丙烯(PP)及PP/稻壳粉复合材料的等温结晶行为,同时利用Avrami方程分析了纯PP和PP/稻壳粉复合材料的等温结晶动力学。结果表明:结晶温度对PP及PP/稻壳粉复合材料的结晶行为具有明显的影响,随着结晶温度的升高,结晶时间延长、结晶速率下降;在等温结晶过程中得到的Avrami指数在2.03~2.5之间,PP及PP/稻壳粉复合材料的晶体为二维盘状生长;稻壳粉在复合材料中起到了良好的异相成核作用,显著地提高了PP的结晶速率。     

超声改性无水硫酸钙晶须对聚丙烯等温结晶行为的影响

用超声法对无水硫酸钙晶须(ACSW)进行改性,并利用差示扫描量热法(DSC)研究了聚丙烯(PP)、PP/ACSW和PP/超声改性无水硫酸钙晶须(UACSW)复合材料的等温结晶行为;用Avrami方程全面分析了复合材料的等温结晶过程,并计算出其结晶动力学参数。结果表明:超声改性后的PP/UACSW复合材料的结晶时间缩短,结晶速率显著提高,证明UACSW能促进PP材料的结晶,并在PP结晶过程中起到异相成核作用。     

聚丙烯/聚磷酸铵复合材料的等温结晶行为

采用差示扫描量热法研究了聚丙烯(PP)聚/磷酸铵(APP)复合材料的等温结晶过程。引入APP后,PP/APP复合材料的平衡熔点升高,结晶速率大幅度提高。采用Avrami方程研究了该体系的结晶动力学,发现PP/APP复合材料呈现明显的异相成核特征,随w(APP)的增加,Avrami结晶速率常数增大,半结晶时间降低。     

聚丙烯/纳米碳酸钙原位聚合复合材料非等温结晶动力学研究

用原位聚合复合法制备PP/纳米CaCO3复合材料,用DSC法研究了不同纳米粒子含量的等速结晶性能和非等温结晶行为。对所得数据分别用修正Avrami方程的Ozawa法和Mo法进行处理,表明Mo法处理PP/CaCO3纳米复合材料非等温结晶过程比较理想。Mo法所得的参数F(T)随结晶度的增加而增大,a随结晶度的增加而增大,但幅度不大。表明降温速率越快,单位结晶时间达到的结晶度越高,各降温速率下的结晶方式基本不变。等速结晶研究表明,纳米碳酸钙的加入起到了结晶成核剂作用。用Kissinger方法计算出PP/纳米CaCO3原位复合材料的活化能为202 4kJ/mol。     

聚丙烯/纳米CaCO3复合材料的结晶行为研究

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。     

PP/PET/POE-g-MAH共混合金的等温结晶动力学特性

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。     

赤泥/聚丙烯复合材料非等温结晶动力学研究

采用DSC研究了聚丙烯(PP)及聚丙烯/赤泥复合材料的非等温结晶动力学,对所得的数据采用了Avrami方程的Jeziorny法及Mo法进行处理.结果表明:赤泥的加入提高了PP的结晶温度和结晶速率,PP的结晶活化能降低,赤泥成核活性高于改性的赤泥.在同样含量下,经钛酸酯偶联剂改性的赤泥使PP结晶温度增加,结晶活化能与赤泥/聚丙烯复合材料相比有小幅的增加.赤泥具有异相成核作用,经表面修饰的赤泥异相成核效果降低.     

SEBS/PP/TPEE共混材料非等温结晶动力学研究

采用双螺杆挤出机制备了SEBS/PP/TPEE共混材料,利用差示扫描量热法(DSC)研究组分PP非等温结晶动力学,研究TPEE在组分PP结晶过程中的作用。结果表明:随着降温速率的增大,组分PP的结晶温度都向低温移动,且结晶峰变宽。TPEE既起阻碍PP分子链运动和排列的作用,降低PP的结晶度和熔点,又起成核剂的作用,降低PP结晶所需能量,提高PP的结晶温度和结晶速率。用Avrami法处理SEBS/PP/TPEE共混材料中组分PP的非等温结晶曲线,n值约为3,TPEE对组分PP起到了异相成核的作用。     

Mechanical properties,morphology, and crystallization behavior of polypropylene/elastomer/talc composites

In this study, polypropylene/ethylene–octene copolymer (PP/POE) blends, PP/talc, and PP/POE/micro‐talc (MT) composites were fabricated using a twin screw. To estimate the performances of the PP/POE blends, PP/talc, and PP/POE/MT composites, mechanical properties, heat deflection temperature (HDT), thermomechanical analysis, and isothermal crystallization characterization were conducted. Incorporating talc particles increased the tensile strength, flexural properties, and HDT of the PP matrix, but reduced the elongation at break and notched impact strength. The inclusion of POE elastomers in the PP matrix yielded the opposite effect on PP/talc composites. PP/POE/MT composites provide a compromise that improves both the flexural properties and notched impact strength. Moreover, the inclusion of talc particles in PP/POE blends induced heterogeneous nucleation and considerably reduced the crystallization time. Consequently, the time required for processing was also greatly reduced. POLYM. COMPOS., 36:69–77, 2015. © 2014 Society of Plastics Engineers     

双单体改性对纳米CaCO3/PP结晶与熔融行为的影响

制备了界面改性纳米CaCO3／PP复合材料，用DSC研究了在有、无过氧化二异丙苯(DCP)存在下，反应单体丙烯酸(AA)及苯乙烯(St)对PP结晶与熔融行为的影响。结果表明：AA改性纳米CaCO3／PP可使结晶温度提高；St改性使纳米CaCO3／PP的结晶温度降低，但在DCP存在下结晶温度反而提高。AA和St双单体改性使纳米CaCO3／PP的结晶温度明显降低，但加有DCP的双单体改性却使纳米CaCO3／PP的结晶温度大幅提高，说明双单体接枝物有促进纳米CaCO3表面成核的作用。     

聚乳酸/可反应性纳米SiO2复合材料的等温结晶动力学

采用熔融共混法制备了聚乳酸/可反应性纳米二氧化硅(PLLA/RNS)复合材料。利用差示扫描量热仪研究了RNS对PLLA等温结晶行为的影响;用Avrami 方程研究了PLLA及其复合材料的等温结晶动力学。结果表明,加入RNS对PLLA结晶起到了异相成核作用,随着RNS含量的增加,PLLA的结晶速率(K)提高,半结晶时间(t1/2)减小,而Avrami指数(n)变化不大,说明RNS没有改变PLLA结晶的成核机理;利用Arrhenius方程和Lauritzen-Hoffman理论分别对PLLA及其复合材料的结晶活化能(ΔE)、成核参数(Kg)和折叠链端表面自由能(σe)进行计算后发现,复合材料的ΔE比纯聚乳酸的小,Kg 、σe略有增加。这表明加入RNS降低了复合材料的ΔE,从而有效地促进了PLLA基体的结晶。     

The rheological modification of talc‐filled polypropylene by epoxy‐polyester hybrid resin and its effect on morphology,crystallinity, and mechanical properties

Reactive mixing of polypropylene (PP) and talc with epoxy‐polyester resin was preformed using a corotating twin screw extruder, and the rheology, morphology, crystallization behavior, and mechanical properties of composites were evaluated. The melts of composites mixed with resin exhibited yield stress and the variation of viscosity against frequency can be approximated in two lines with various slopes. The measurement of the suspension viscosity can be used to characterize the microstructural state of dispersion. Empirical formula was used to relate viscosity with particle concentration, and the analysis showed that the maximum volume fraction increases by using small amount of epoxy resin in the formulations. The morphological study of composites by scanning electron microscopy revealed that the use of resin improved the dispersion of talc in PP, which leads to the arrangement of talc platelets in the direction of flow even close to wall of the mold. The differential scanning calorimetry showed that the epoxy resin suppressed the nucleation effect of talc on PP while the degree and rate of crystallization increased. The compatibilization by maleic anhydride‐grafted polypropylene showed a noticeable increase in tensile strength of composites reactively mixed with epoxy resin. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers     

Crystallization behavior of polypropylene filled with surface-modified talc

Talc-filled polypropylene (PP) composites were prepared by extrusion in a wide composition range (0–40 wt %). To improve the affinity relation between talc and the PP matrix, we modified the talc surface with silane coupling agents. Differential scanning calorimetry investigations on test samples, prepared by injection moulding, revealed that the talc content and its surface modification had a pronounced effect on the crystallization behavior of the filled PP composites. The experimental results indicate that a talc concentration of 2 wt % strongly affects the nonisothermal crystallization process of the PP, especially when talc is silane treated Isothermal crystallization experiments on samples with minimum amounts of talc (2 wt %) revealed an improved nucleation activity with silane-treated talc. © 1996 John Wiley & Sons, Inc.     

聚丙烯/蒙脱土纳米复合材料的结晶性能研究

采用差示扫描量热法研究蒙脱土(MMT)对聚丙烯(PP)等温结晶性能的影响。结果表明：加入MMT后提高了PP的结晶速率，使结晶度增大，但对PP熔点的影响不大；加入相容剂PP-g-MAH后，使有机MMT对PP的成核作用更加明显，从而提高了PP／MMT。纳米复合材料的结晶度；PP／MMT纳米复合材料的n值在3左右，其成核方式是异相成核方式。     

Crystallization kinetics of polypropylene composites filled with nano calcium carbonate modified with maleic anhydride

The subject of this study was the crystallization behavior and thermal properties of polypropylene (PP)/maleic anhydride (MAH) modified nano calcium carbonate (nano‐CaCO₃) composites. In this study, 5 wt % nano‐CaCO₃ modified with different contents of MAH was filled into a PP matrix. X‐ray diffraction and differential scanning calorimetry were used to characterize the crystal morphology and crystallization kinetics of a series of composites. The results demonstrate that the nano‐CaCO₃ modified with MAH had an important effect on the thermal and morphological properties of the nanocomposites. The Avrami exponent of the pure PP was an integer, but those of the composites were not integers, but the crystallization rate constant decreased as the content of MAH in the nano‐CaCO₃ filler increased in isothermal crystallization. In nonisothermal crystallization, the kinetic parameter F(T) and the degree of crystallinity of pure PP were compared with those of the PP composites filled with nano‐CaCO₃. We suggest that heterogeneous nucleation existed in the PP composites and that the transformation and retention of the β‐form crystal into the α‐form crystal took place in the composite system and the β‐form crystal had a higher nucleation rate and growth process than the α‐form crystal in the PP composites. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Crystallization Behaviors of amino-terminated polyurethane (ATPU)-grafted polypropylene

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, t_1/2, the crystallization rate of functional PP blends was faster than that of PP homopolymer at a given crystallization temperature.