聚丙烯/共聚酯/蒙脱土复合材料结晶行为的研究

采用热台偏光显微镜研究了聚丙烯(PP)/共聚酯(COPET)以及PP/COPET/蒙脱土(MMT)复合材料等温结晶时的结晶形态,结果表明:两样品均呈现清晰的球晶所特有的黑十字消光图像,PP/COPET/MMT复合材料的球晶尺寸比PP/COPET样品的球晶尺寸大大减小。采用差示扫描量热法对PP/COPET以及PP/COPET/MMT复合材料的非等温结晶行为进行了研究,结果表明:随着MMT含量的增加,复合材料样品的结晶初始温度和结晶峰温基本呈现逐渐降低趋势,结晶放热焓随MMT含量增加先增加后减小;在不同的降温速率下结晶,两种样品结晶峰温均随降温速率的增大而降低,结晶放热焓也随着结晶速率的增大而降低。采用Jeniorny法处理了PP/COPET和PP/COPET/MMT样品的非等温结晶过程,得出了两体系的结晶速率总体上随着冷却速率的增加而加快,为多维结晶生长体系。     

聚丙烯/海泡石复合材料的等温结晶行为

采用熔融共混的方法制备聚丙烯（PP）/海泡石复合材料,通过示差扫描量热仪和偏光显微镜研究有机化改性海泡石填充PP复合材料在不同温度下的等温结晶行为,考察海泡石对PP结晶行为的影响,采用Avrami方程处理等温结晶过程,并计算结晶动力学参数。结果表明,海泡石的加入使复合材料的结晶时间缩短,结晶度增大;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n、K降低,并且随着结晶温度（Tc）的升高,半结晶时间（t1/2）增大;在同一结晶温度（Tc）下,海泡石的加入提高了基体的结晶速率,加快了PP的异相成核过程,使得PP球晶尺寸减小。     

PBT/OMMT共混体系的非等温结晶行为

通过熔融共混法制备了聚对苯二甲酸丁二醇酯/有机蒙脱土(PBT/OMMT)复合材料,并对其非等温结晶性能和力学性能进行了研究。结果表明:随着OMMT含量的增加,PBT/OMMT复合材料的结晶峰温向高温方向移动,结晶峰变得狭窄且半结晶时间变得更短;随着冷却速率的增加,PBT/OMMT复合材料的结晶峰温度向低温移动且半结晶时间变得更短。利用热台偏光显微镜观察PBT和PBT/OMMT复合材料的球晶形态,PBT/OMMT复合材料球晶相比纯PBT变得更小,且边界更不清晰。     

分散剂对松香型成核透明PP结晶行为和透明性的影响

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。     

等规聚丙烯在静态条件下的结晶行为北大核心

采用热台偏光显微镜研究了等规聚丙烯(i PP)结晶形态随时间的变化。通过控制目标结晶温度,比较了不同结晶温度条件下,成核速率、球晶生长速率随时间的变化以及温度对结晶完成时间的影响,并讨论了相对分子质量对结晶速率的影响。结果表明:等温结晶时,晶核数目和球晶直径都与时间呈良好的线性关系;成核速率与球晶生长速率均随温度的升高而逐渐降低;结晶完成时间实际上是球晶生长速率的反映,随温度的升高而增加;相对分子质量对i PP结晶速率的影响程度具有明显的温度依赖性,温度较低时,影响不明显,随着温度的升高,影响逐渐增大,并且成核时间和结晶完成时间均随着相对分子质量的增加而增加。     

等规聚丙烯在静态条件下的结晶行为

采用热台偏光显微镜研究了等规聚丙烯(i PP)结晶形态随时间的变化。通过控制目标结晶温度,比较了不同结晶温度条件下,成核速率、球晶生长速率随时间的变化以及温度对结晶完成时间的影响,并讨论了相对分子质量对结晶速率的影响。结果表明:等温结晶时,晶核数目和球晶直径都与时间呈良好的线性关系;成核速率与球晶生长速率均随温度的升高而逐渐降低;结晶完成时间实际上是球晶生长速率的反映,随温度的升高而增加;相对分子质量对i PP结晶速率的影响程度具有明显的温度依赖性,温度较低时,影响不明显,随着温度的升高,影响逐渐增大,并且成核时间和结晶完成时间均随着相对分子质量的增加而增加。     

新型复合成核剂对PP/POE共混物结晶行为的影响

以低分子量聚酰胺6为主体制备了新型复合成核剂,采用高级流变仪、差示扫描量热仪、偏光显微镜等分析手段研究了几种成核剂对聚丙烯/乙烯-1-辛烯共聚物(PP/POE)共混物结晶温度、结晶形态及流变行为的影响。结果表明:新型复合成核剂均可以提高PP/POE共混物的结晶温度、结晶度和结晶速率,减小共混物的球晶尺寸,增加晶核密度,显著提高了PP/POE共混物的结晶性能。     

聚丙烯/聚苯乙烯/膨润土共混体系的结晶性能和热性能研究

通过偏光显微镜(PLM)和光学解偏振仪对聚丙烯/聚苯乙烯/膨润土三元共混体系的结晶形态和等温结晶速率进行了研究。结果表明:共混体系所形成的球晶比纯聚丙烯(PP)所形成的球晶尺寸小,聚苯乙烯(PS)/膨润土(Garamite)复合粒子的加入导致PP的结晶成核和生长发生了改变,加快了PP的结晶速率。同时采用差示扫描量热仪(DSC)对该三元共混体系的热性能进行了研究,结果表明,随着膨润土含量的增加,共混体系熔融温度变高,结晶温度变高,结晶度下降。     

高相对分子质量聚丙烯的成核行为

在反应器内合成了不合成核剂及含有成核剂的高相对分子质量聚丙烯(HMWPP)，将其与均聚聚丙烯(F401)混合制备了成核改性的PP。用差示扫描量热计和偏光显微镜分析了混合体系的结晶行为和形态。结果表明，HMWPP可以诱导β晶形成，细化PP球晶，使材料冲击强度增加50％。而成核剂与HMWPP共同作用使PP的结晶温度和结晶速率显著升高，球晶尺寸细化，弯曲模量增加32％，热变形温度提高18℃。     

PET/PTT合金结晶形态的研究

采用XP-201热台偏光显微镜研究了对苯二甲酸乙二醇酯（PET）/对苯二甲酸丙二醇酯（PTT）合金等温结晶时的结晶形态及影响因素。研究结果表明：随着等温结晶温度的升高,PET/PTT(40/60)合金的结晶诱导期变长;在观察的时间范围内各样品的球晶尺寸随着时间的延长而增大;随着PTT含量的增加,样品球晶的线生长速率增大,球晶尺寸增大;对比不同温度下等温结晶的球晶形态,PET/PTT(100/0)样品在190℃结晶时球晶尺寸最大, PET/PTT(40/60)样品和PET/PTT(100/0)样品在180℃结晶时球晶尺寸最大; PET/PTT(0/100)样品等温结晶时呈现出了复杂的条带球晶。     

PP/纳米TiO2复合材料的晶体形貌和非等温结晶行为

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 %。     

Study on the crystallization kinetics of PP/GF composites

The crystallization kinetics and morphology of glass fiber-reinforced polypropylene (PP/GF) were investigated in this work. Both isothermal and nonisothermal crystallization behaviors of 90PP/10GF, 80PP/20GF, and 70PP/30GF were examined with a DSC instrument. It was found that the addition of glass fiber would increase the crystallization rate of PP and increase the content of β spherulite, which was most likely formed at temperatures between 390 and 400 K. The morphology of spherulites of PP/GF composites were examined with SEM and a polarized microscope. All experimental observations conformed rather well with the theoretical approach, a dynamic crystallization model, proposed in our previous work. The size of α spherulites of PP would decrease at lower crystallization temperature, or at higher cooling rate, or by adding glass fiber in it.     

Melting and crystallization behaviors,morphology, and mechanical properties of β‐polypropylene/polypropylene‐graft‐maleic anhydride/calcium sulfate whisker composites

The melting and crystallization behaviors, morphology, and mechanical properties of polypropylene (PP)/surface‐treated calcium sulfate (CaSO₄) whisker (T‐CSW), β‐PP/T‐CSW, and β‐PP/polypropylene‐graft‐maleic anhydride (PP‐g‐MAH)/T‐CSW composites had been investigated via differential scanning calorimetry (DSC), wide angle X‐ray diffraction (WAXD), polarized light microscopy (PLM), scanning electron microscopy (SEM), and mechanical tests. We found that T‐CSW was an α‐nucleating agent and increased the crystallization temperatures of PP, but PP‐g‐MAH and high loadings of T‐CSW had weakly negative effects on the crystallization rates of PP. The T‐CSW restrained the formation of β‐spherulites, and the spherulitic size decreased in the composites. PP‐g‐MAH improved the compatibility and adhesion between T‐CSW and the matrix. The notched impact strength was improved, and the tensile strength was enhanced at low levels of T‐CSW, while the flexural modulus was weakened for β‐PP/T‐CSW and β‐PP/PP‐g‐MAH/T‐CSW composites versus PP/T‐CSW composites. POLYM. COMPOS., 37:2121–2132, 2016. © 2015 Society of Plastics Engineers     

Effect of nylon 6 inclusions on the crystalline morphology of polypropylene–nylon 6 blends

Crystallization behavior and crystalline morphology of plain polypropylene (PP) and its blend with 0 to 30 wt % nylon 6 were studied by the hot‐stage polarized light microscopy method. Radial growth rate and the size and number of PP spherulites were measured as a function of both the isothermal crystallization temperature and the nylon 6 content of the blend. The study revealed that a reduction in the isothermal crystallization temperature from 135 to 120°C, for both the plain PP and its blend with nylon 6, leads to the formation of a large number of fast‐growing, small spherulites. Moreover, the size and growth rate of PP spherulites decreased on increasing the nylon 6 content of the blend; whereas the number of PP spherulites decreased sharply on initial addition of 10% nylon 6 and, thereafter, increased slightly by further addition of nylon 6. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 1769–1775, 2000     

Development of Crystalline Morphology,Structure, and Impact Property of Isotactic Polypropylene and Poly(cis-Butadiene) Rubber Blends During Mixing

The development of crystalline morphology, structure, and impact property of isotactic polypropylene (PP) and poly(cis-butadiene) rubber (PcBR) (vol. %: 80/20) blends during mixing were investigated and compared to neat PP. It was found by polarized optical microscopy (POM) and small-angle light scatter (SALS) that the incorporation of PcBR into PP caused small and imperfect PP spherulites and more diffused spherulite boundaries, which sharply exhibited in the initial 2 min of mixing but remained almost unchanged in the rest of the mixing time. Crystalline structure of neat PP and blends was studied by wide-angle x-ray diffraction (WAXD). The addition of PcBR into PP induced formation of PP β-form spherulites. As mixing time developed, the relative degree of crystallization decreased whereas interplanar distance increased. Impact strength of PP and blends was tested. The result showed that impact strength of blends significantly improved with increase of the mixing time.     

Supermolecular morphology of polypropylene filled with nanosized silica

The supermolecular morphology of injection‐molded SiO₂/polypropylene (PP) nanocomposites was investigated via thin sections analyzed under polarized light and the systematic development of an appropriate etching technique, which allowed the study of the supermolecular morphologies with light microscopy (LM) and high‐resolution field emission scanning electron microscopy (FESEM). In parallel, information regarding the dispersion, distribution state, and morphology of SiO₂ particles was investigated via transmission electron microscopy (TEM) and scanning electron microscopy (SEM) of the ion‐polished and fractured surfaces of SiO₂‐filled PP. The TEM/SEM results demonstrated an almost homogeneous dispersion and distribution of SiO₂ particle agglomerates in the PP matrix. With polarized transmitting LM, reflecting LM, and FESEM, the spherulitic structure of the nanocomposites could be visualized to obtain information on the nanoparticle influence on the crystallization and structural behavior. The size and size distribution of the spherulites analyzed with transmitting light (thin sections) and reflecting light (etched specimens) showed an excellent correlation. With increasing filler loading, the mean size of the spherulites decrease as did the degree of crystallinity. This was a clear indication that the particles acted as nucleation agents and, on the other hand, hindered the arrangement of the molecules during the crystallization. As a result, the particles were most likely located in three areas: the center of the spherulites, the areas between the highly crystalline branches, and the spherulite boundaries. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39655.     

PP/稀土铝酸锶发光材料的制备及性能研究

采用熔融共混的方法制备了聚丙烯（PP）/稀土铝酸锶复合材料,研究了稀土铝酸锶用量对PP/稀土铝酸锶复合材料结晶性能、力学性能和光学性能的影响。结果表明,稀土铝酸锶的加入没有改变PP的晶型;稀土铝酸锶起异相成核作用,结晶度随着稀土铝酸锶含量的增加有不同程度的增加,与PP相比,复合材料的球晶尺寸细小而均匀;PP/稀土铝酸锶复合材料的拉伸强度和断裂伸长率均随着稀土铝酸锶含量的增加出现先增大后减小的趋势;随着稀土铝酸锶含量的增加,复合材料的初始光强度逐渐增大,而发光强度衰减曲线均呈指数规律衰减。     

Crystallization behavior of polypropylene in polypropylene/nylon 6 blend

This article describes the crystallization behavior of polypropylene (PP) in the presence of a crystallizable polymer, namely, nylon 6, in the binary blend of PP/nylon 6 in the composition range from 0 to 30 wt % of nylon 6 content in the blend. The crystallization behavior was studied through variation of the crystallinity with the blend composition and changes in the crystallization exotherms were recorded by differential scanning calorimetry (DSC) and the spherulite morphology was observed via polarized light microscopy (PLM). Comparison of the crystallization exotherms and melting endotherms revealed some differences which are attributed to the role of a sufficiently high thermal energy of the nylon 6 crystals on the melting of PP. The crystallinity of PP decreased in the presence of nylon 6, whereas the crystallinity of nylon 6 increased considerably in the presence of PP. The rate of nucleation of PP on addition of nylon 6 decreased rapidly in the region 0–10 wt % nylon 6 content, and, thereafter, at a higher nylon 6 content, decrease of the nucleation rate was relatively slow. PLM observation revealed the presence of composite spherulites with PP spherulites grown on the surface of the already‐formed nylon 6 spherulites. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1153–1161, 1999     

Deformation and pore formation mechanism under tensile loading in isotactic polypropylene

Four different polypropylene (PP) samples were prepared through isothermally crystallizing at 0 °C (PP‐Q), 80 °C (PP‐80), 100 °C (PP‐100) and 120 °C (PP‐120). The results of differential scanning calorimetry, wide‐angle X‐ray diffraction, polarized light microscopy and tensile testing indicate that the spherulite structure gradually improves with increasing isothermal crystallization temperature. Meanwhile, the interface between spherulites becomes more obvious due to the larger dimension and the higher strength of spherulites. Therefore, the trend of interfacial debonding during stretching is enhanced distinctly. In addition, based on the structural characterization of samples at different draw ratios, two completely distinct morphological changes are demonstrated. There are no defects generated after longitudinal stretching within PP‐Q, because intra‐spherulitic deformation predominates, which is caused by the imperfect spherulites of PP‐Q. As a result, no microporous structure is produced after sequential biaxial stretching. And the improvement of the crystalline structure makes interfacial debonding more likely to occur. Therefore, fully developed crazes and cracks disperse between microfibril structures after longitudinal stretching. Furthermore, numerous microporous structures are produced through debonding of fully developed crazes and cracks after sequential biaxial stretching. Meanwhile, the quantity, dimension and uniformity of the microporous structures and the porosity are gradually improved. © 2017 Society of Chemical Industry