透明成核剂对聚丙烯的非等温结晶行为的影响

采用热分析方法研究了透明成核剂TM-3对聚丙烯(PP)非等温结晶行为的影响,并与纯PP样品作了比较.结果表明,TM-3能够提高聚丙烯的结晶温度12℃左右;分别采用了Avrami和莫志深方法对非等温结晶过程作了分析处理;对含有成核剂的PP样品的非等温结晶行为分析显示,成核剂的加入改变了聚丙烯的结晶行为,使其成核与结晶生长过程复杂化.     

成核剂对1-丁烯聚合及聚1-丁烯结晶性能的影响

采用齐格勒-纳塔催化剂,在2 L聚合釜中进行1-丁烯的本体聚合,聚合过程中加入成核剂,考察了成核剂种类对聚合性能和聚1-丁烯结晶性能的影响。结果表明:釜内添加成核剂使催化剂活性下降,对聚1-丁烯的相对分子质量造成一定影响;加入成核剂使聚1-丁烯的熔融温度及结晶度均提高,未加成核剂时熔融温度为126.8℃,加入成核剂后熔融温度最高达130.6℃,结晶度由49.0%提高到56.2%;加入酰胺类和磷酸酯盐类成核剂对加快聚1-丁烯晶型转变效果最佳。     

一种新型复合成核剂对PET结晶性能和摩尔质量的影响

采用双螺杆挤出机,以熔融挤出法制备了含不同结晶成核剂的聚对苯二甲酸乙二醇酯(PET)样品.利用差示扫描昔热法(DSC)、黏度法研究了成核剂对PET结晶行为和摩尔质量的影响,并对比了复合成核剂(苯甲酸钠/酯交换剂A)与常用成核剂苯甲酸钠及乙烯/甲基丙烯酸共聚物的离聚物(Surlyn)对PET结晶行为和摩尔质量的影响.研究结果表明:在成核能力方面,复合成核剂的效果优于苯甲酸钠和Surlyn;同时,复合成核剂的加入还能有效地降低PET摩尔质馈的损失程度,加入复合成核剂的PET摩尔质量明显高于加入苯甲酸钠的PET样品,与加入Surlyn成核剂的PET样品摩尔质量接近.     

取代芳基杂环磷酸酯类成核剂在薄壁注塑煤基聚丙烯中的应用研究

针对两种取代芳基杂环磷酸酯类成核剂NA21、TD531对薄壁注塑煤基聚丙烯K1860的结晶性能、力学性能以及光学性能的影响进行研究。结果表明:不同浓度成核剂的加入使得结晶峰温度、拉伸强度、弯曲模量较空白样品有了明显提升,尤其是在低质量分数为0.075%时,结晶峰温度分别较空白样品提升5.08%、5.81%,拉伸强度分别较空白样品提升了10.6%、11.5%,弯曲模量分别较空白样品提升了24.2%、21.1%,为薄壁注塑煤基聚丙烯专用料的开发中关于成核剂的优选提供一定的工业参考价值。     

α成核剂和β成核剂对高流动性聚丙烯结晶行为的影响

研究了α成核剂和β成核剂对高流动性聚丙烯(PP)结晶行为的影响,采用偏光显微镜、差示扫描量热法和广角X衍射对其微观结构和结晶形态进行了表征。结果表明:α成核剂的加入细化球晶而不改变结晶形态;β成核剂的加入改变球晶的形态,使部分α晶型向β晶型转变;两种成核剂的加入使高流动性PP的结晶速率加快结、晶过程的成核方式和生长机理发生改变,结晶活化能降低。     

β成核剂改性iPP的熔融结晶行为与力学性能研究

采用3种β成核剂(NT-A,NT-B和NT-C)制备了β晶等规聚丙烯(β-iPP)样品,应用差示扫描量热仪(DSC)分析、偏光显微镜(POM)观察和力学性能测试研究了β-iPP的熔融、结晶行为和力学性能。结果表明:加入β成核剂后,诱导iPP由α晶向β晶转变,结晶温度提高,球晶明显细化。3种β成核剂的成核效率和改性样品的缺口冲击强度顺序为NT-C>NT-B>NT-A,添加NT-C质量分数0.050%时,样品的最大缺口冲击强度可达纯iPP的3.7倍。     

成核剂对聚丙烯力学性能与结晶行为的影响

研究了两种类型的成核剂对国产共聚聚丙烯的结晶形态以及拉伸强度、冲击强度的影响。结果表明:加入TMB-5型成核剂,聚丙烯的冲击强度有一定程度改善,w(TMB-5)为0.1%时,改性聚丙烯的缺口冲击强度达到最大;TMX-2型成核剂可改善聚丙烯的拉伸性能,但抗冲击性能降低较大;TMB-5型成核剂可显著地改变聚丙烯的结晶行为,诱导聚丙烯在结晶过程中主要形成β晶;TMX-2型成核剂可诱导聚丙烯在结晶过程中主要生成α晶,与纯PP相比,α晶的形成能力增强。     

透明成核剂作用下的等规聚丙烯的结晶形态

利用偏光显微镜观察了等规聚丙烯（iPP）在透明成核剂TM-3作用下的等温结晶形态，并与普通成核剂苯甲酸钠的影响作了对比。结果表明：等温和等成核剂含量条件下，含有TM-3样品的最佳结晶完善程度出现在结晶时间为10h时；其他条件相同时，TM-3／iPP样品的最佳结晶完善程度出现在140℃；而TM-3／iPP样品的结晶完善程度在成核剂含量为0．3％（质量分数）时最好。作为一种新型成核剂，TM-3的成核机理不再是简单的异相成核，而是提供少量而有效的生长点，使PP链段进行附着生长。结果证实，TM-3具有明显促进iPP球晶生长的能力。     

成核剂对PET晶体形态及力学性能的影响

通过高温下聚对苯二甲酸乙二酯(PET)熔体的结晶速率常数和球晶出现时间研究了不同成核剂对成核速率的影响,利用偏光显微镜、X射线衍射分析了成核剂对晶体形态的影响,结合退火处理研究了晶粒尺寸、成核剂对PET力学性能的影响。结果表明,成核剂的加入起到了快速成核和晶粒细化的效果,提高了材料的拉伸强度与缺口冲击强度,其中0.5%的成核剂Aclyn对PET的增韧改性效果最好,可使冲击强度增大2.2倍,同时使拉伸强度增大1.9倍。样品退火处理2 h后由于晶粒尺寸的增大其缺口冲击强度下降34%。     

β成核剂对聚丙烯发泡材料的结晶行为和发泡性能的影响

在聚丙烯(PP)中加入β成核剂(TMB-5),以超临界二氧化碳(CO2)作为发泡剂,用高压发泡釜对其进行间歇发泡。研究β成核剂用量、饱和温度、饱和压力对β成核/PP发泡材料的结晶和发泡性能的影响。结果表明,β成核剂有效促进了β晶的形成,发泡材料中β晶相对含量最高可达到92.4%,但增大饱和压力却会抑制β晶产生。β成核剂同时起到异相成核作用,使泡孔成核更容易,制得的样品发泡性能较好。另外,饱和温度的升高会使PP熔体强度降低,导致泡孔的尺寸增大、密度减小;而随着饱和温度降低,饱和压力升高,气体在熔体中的溶解度增大,泡孔成核数量增多,使泡孔密度增大、泡孔尺寸减小。饱和压力为22 MPa时,泡孔密度可达2.72×108个/cm3。     

Study on Mechanical Properties and Crystallization Behavior of Polypropylene and Its Blends Modified by β Crystalline Form Nucleating Agent

The influence of β crystalline form nucleating agent (β nucleator) on the mechanical properties of homo-polymerized polypropylene (PPH), random-copolymerized polypropylene (PPR), block-copolymerized polypropylene (PPB), and PPH/PPR/PPB blends was studied. Polarized optical microscopy (POM), differential scanning calorimetry (DSC), and wide angle X-ray diffraction (WAXD) were used to characterize the crystalline morphology and behavior. The results indicated that α crystalline form of polypropylene (PP) had transformed to β crystalline form by adding 0.5% β nucleator; in the meantime, the toughness of PP and its blends was enhanced. That is, 0.5% β nucleator helped to improve the notched impact strength of PPH, PPR, and PPH/PPR/PPB blends by 130%, 40%, and 40%, respectively, without losing the tensile strength and flexural strength.     

基体性质对GMT-PP复合材料力学性能的影响

研究了基体树脂的性质及基体配方中炭黑、结晶成核剂、接枝极性基团的功能化聚丙烯（ＰＰ）等对玻璃纤维毡增强ＰＰ复合材料力学性能的影响。结果表明：提高基体树脂熔体的流动性,有利于复合体系的浸渍过程;复合材料的弯曲强度及模量随基体树脂强度及模量的增大而提高;采用韧性较好的ＰＰ或ＰＰ增韧体系作为基体,可获得抗冲性能较好的复合材料;随着炭黑加入,复合体系的弯曲及冲击强度有所下降;结局成核剂的加入,可改善复合体     

Interactions between sorbitol-type nucleator and additives for polypropylene

The thermal properties of a sorbitol-type nucleating agent (viz. 1,2,3-trideoxy-4,6:5,7-bis-O-[(4-propylphenyl)methylene]-nonitol (TBPMN)) were examined in this study, and the influence of common processing additives assessed. In addition, we describe a novel approach to monitor in situ the self-assembly of the nucleator in presence of additives by optical microscopy. The performance of sorbitol compounds is closely associated to their chemical structure and ability to self-assemble. TBPMN formed elongated fibrils from the melt under inert atmosphere, in molted polypropylene, or in presence of antioxidants. However, calcium stearate (CaSt) and glycerol monostearate hampered growth, and yielded thinner fibrils. In presence of the additives, melting point depression of the nucleator occurred, and resulted in a lower degree of crystallinity upon cooling. Performance evaluation of the nucleator in polypropylene blends revealed an increased crystallization temperature when antioxidants were present, while CaSt inhibited nucleator activity. The effect of mono-glycerides was found highly dependent on the processing conditions. Noteworthy, blends containing all the additives displayed the highest performance. This study highlights the importance of the preparation method of polymer additive blends to achieving the best performance in the final product. Characterization was performed by thermogravimetric analysis, Fourier-transform infrared spectroscopy, optical microscopy, and differential scanning calorimetry.     

Combined effect of specific nucleation and rubber dispersion on morphology and mechanical behavior of isotactic polypropylene

This study aims to explore the joint effects of specific β‐nucleation and rubber dispersion on morphology and mechanical behavior of materials derived from isotactic polypropylene. A β‐nucleator (N,N′‐dicyclohexylnaphthalene‐2,6‐dicarboxamide) and an amorphous EPM rubber were used for the modification of isotactic polypropylene. Four samples were investigated: neat polypropylene, the same polymer modified with 0.03 wt % of β‐nucleator or with 15 wt % of dispersed rubber particles, and finally polypropylene containing both the β‐nucleator and the rubber particles. Tensile and impact behavior were followed at room and cryogenic temperatures. It has been observed that the β‐nucleation and rubber modification have brought about a similar macroscopic softening effect on the tensile mechanical behavior. Microscopy of fracture surfaces, however, has shown different toughening mechanisms caused by specific nucleation on one hand and by rubber dispersion on the other. While a distinct synergy effect of nucleation and rubber modification on the resulting toughness was found at low temperature, no such cooperative effect manifested itself at room temperature. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3539–3546, 2007     

Effect of the composition ratio of pimelic acid/calcium stearate bicomponent nucleator and crystallization temperature on the production of β crystal form in isotactic polypropylene

The influence of the composition ratio of pimelic acid/calcium stearate bicomponent nucleator on the β crystal form content of isotactic polypropylene (iPP) had been studied at the crystallization temperature of 120°C and duration of 30 min. It was found that the β crystal form content increased continuously with increasing amount of calcium stearate at the constant amount of 0.15% pimelic acid. High β crystal form content polypropylene could be produced when the amount of calcium stearate was greater than 0.30% (the mass composition ratio of pimelic acid/calcium stearate was less than 1/2, the mole ratio was less than 1.89/1). It was shown that pimelic acid and calcium stearate could react to produce a high effective β nucleator (calcium pimelate) “in situ” during the melt‐mixing of iPP and the bicomponent nucleator. The influence of crystallization temperatures (100–140°C) on the β crystal form content of iPP had also been studied at the constant composition ratio of 0.15% pimelic acid/0.5% calcium stearate (the calcium pimelate produced in situ was 0.16%, which was calculated from stoichiometry). It was found that the β crystal form content increased continuously with increasing crystallization temperature and it maximized at 130°C. β Crystal form content decreased sharply at the crystallization temperature of 140°C. It was shown that β → α modification transformed between 130 and 140°C. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

几种国产聚丙烯透明成核剂性能的研究

研究了采用国产三代山梨醇透明成核DMDBS制备的透明聚丙烯的光学性能、结晶性能、机械性能与热性能。研究表明,在0~2500ppm内随着添加量的增加,国产三代山梨醇透明成核剂与美利肯3988i具有相似的浊度变化曲线。在同样的添加量下,国产三代山梨醇透明成核剂具有与3988i相近的光学性能、结晶性能、机械性能与热变形温度,且无气味,可作为替代进口透明剂、降低生产成本的有效途径。     

Effect of β-phase nucleating additives on structure and properties of blow extruded polypropylene

The structure development and mechanical properties of blow extruded polypropylene containing β-phase nucleating additives was studied. Quinacridone red and cadmium red were both found to nucleate the β phase in polypropylene, the former being a much more efficient nucleator than the latter. The β-phase spherulites formed in the presence of these nucleating agents were small and extensively volume filled, yielding high crystallinity. The modulus increased 2–3 times, elongation at break decreased, and there was a sharp break point without much yield when the β-phase nucleating agents were added as compared to the pure α-phase polypropylene. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 1247–1253, 1997     

耐热高抗冲聚丙烯结晶行为及微观形态研究

β成核剂能对聚丙烯进行改性,考察β成核剂改性共聚聚丙烯的结晶行为及微观形态。结果表明,β成核剂只改变β晶型含量,对β晶型内部结构没有影响,且对共聚聚丙烯中α晶型的影响不明显。偏光显微镜观察发现,辐射β球晶和环带β球晶均呈略微彩色,有明显Maltese黑十字。     

Effect of nucleating duality on the formation of γ‐phase in a β‐nucleated isotactic polypropylene copolymer

BACKGROUND: It is a challenge for polymer processing to promote the formation of γ‐phase under atmospheric conditions in isotactic polypropylene (iPP) copolymer containing chain errors. Incorporation of an α‐nucleator in iPP copolymer seems reasonable since it can enhance non‐isothermal crystallization. Up to now, however, the issue regarding a β‐nucleated iPP copolymer still remains unclear, which is the subject of this study. RESULTS: The results indicate that the γ‐phase indeed occurs in a β‐nucleated random iPP copolymer with ethylene co‐unit (PPR) sample and becomes predominant at slow cooling rates (e.g. 1 °C min^?1) where the formation of the β‐form is suppressed to a large extent. With detailed morphological observations the formation of γ‐phase in the β‐nucleated PPR sample at slow cooling rate is unambiguously attributed to the nucleating duality of the β‐nucleator towards α‐ and β‐polymorphs. The α‐crystals, induced by the β‐nucleator, serve as seeds for the predominant growth of the γ‐phase. Moreover, the presence of the β‐nucleator, acting as heterogeneous nuclei, promotes the formation of γ‐phase in the nucleated PPR sample, at least to some extent. CONCLUSION: The findings in this study extend our insights into the formation of γ‐phase in β‐nucleated iPP copolymer and, most importantly, provide an alternative route to obtain iPP rich in γ‐phase. Copyright © 2008 Society of Chemical Industry     

Physico-Mechanical,Interfacial, Degradation,and Dielectric Properties of Jute/PP Composites: Effect of Dye and Gamma Radiation

Jute fabrics/polypropylene composites were prepared by compression molding. Jute fabrics were treated with red dye solutions (0.1–1%, w/w) for different soaking times and we found that 0.5% red-dye-treated jute/PP composite for 5 min soaking time showed better results. Gamma radiation (250-1000 krad dose) was applied on both jute and matrices. Composites were fabricated with non-irradiated jute/non-irradiated PP (C-0), non-irradiated jute/irradiated PP (C-1), irradiated jute/non-irradiated PP (C-2), and irradiated jute/irradiated PP (C-3). It was found that a C-3 composite made using 500 krad dose showed the best results. Simulating weathering and dielectric properties of the composites were also performed.