聚丙烯酸盐成核剂制备及在聚丙烯中的成核效果

制备了一类新型高分子型聚丙烯酸盐类成核剂。通过分子量为300万～700万的聚丙烯酸钠分别与氯化钡、氯化钙和氯化锌进行反应,制得了聚丙烯酸钡、聚丙烯酸钙和聚丙烯酸锌三种成核剂,通过傅立叶变换红外光谱仪、X射线光电子能谱分析仪表征合成产物的结构。利用差示扫描量热仪分析了成核剂对等规聚丙烯(iPP)成核效果的影响,结果表明,在制备的三种聚丙烯酸盐成核剂中,聚丙烯酸钡能够明显提高iPP的结晶峰温度。同时,研究了聚丙烯酸钡成核剂在iPP中的最佳添加量,发现聚丙烯酸钡添加量为0.3%时,改性iPP的结晶峰温度比空白iPP增加了6.5℃。非等温结晶动力学研究结果表明,加入聚丙烯酸钡成核剂没有改变iPP结晶的生长方式。综合来看,聚丙烯酸钡是一种优良的iPP α成核剂。     

辛二酸钙成核改性等规聚丙烯研究

研究了1种高效β晶型成核剂辛二酸钙(CaSu)的用量对等规聚丙烯(iPP)熔融、结晶行为和力学性能的影响。结果表明,CaSu为良好的β晶型成核剂,添加0.20%(质量分数)CaSu,β晶型含量可以达到84.02%;添加CaSu可以使iPP的成核能力增强,使其结晶温度增加;CaSu诱导iPP产生大量β晶型,同时降低了球晶的尺寸;添加CaSu可使iPP的缺口冲击强度、拉伸强度以及断裂伸长率提高,但弯曲模量降低。     

辛二酸/硬脂酸钙双组分成核剂对等规聚丙烯中β晶生成的影响

研究了在120 ℃等温结晶30 min 的条件下,辛二酸/硬脂酸钙双组分成核剂对等规聚丙烯中β晶含量的影响。当加入0.15 %的辛二酸时,等规聚丙烯的β晶消失。固定辛二酸含量为0.15 %、硬脂酸钙含量超过0.525 %时,等规聚丙烯中又开始出现β晶,当硬脂酸钙含量为0.675 %时,β晶含量达到最大值。红外分析表明,辛二酸和硬脂酸钙在双螺杆挤出机中发生原位化学反应,生成高效成核剂辛二酸钙。     

庚二酸类成核剂对等规聚丙烯β晶结晶行为的影响

研究了结晶温度（100～140℃）对添加庚二酸钠、庚二酸锌、庚二酸钙、庚二酸钡成核剂的等规聚丙烯中β晶结晶行为的影响。发现庚二酸钠、庚二酸锌、庚二酸钙和庚二酸钡是有效的β晶型成核剂，随着结晶温度的提高，成核改性聚丙烯的β晶型含量持续增大，并在130℃时达到最大值，结晶温度在130℃～140℃之间，成核改性的聚丙烯发生明显的β→α晶型转变。β晶型成核效率由大到小的顺序为：庚二酸钙〉庚二酸钡〉庚二酸锌〉庚二酸钠，庚二酸钙是最佳β晶型成核剂。     

脱氢枞酸盐透明改性聚丙烯研究

以脱氢枞酸钾和脱氢枞酸钾成核剂对透明聚丙烯（PP）进行改性，研究了脱氢枞酸盐对PP光学性能、力学性能及结晶特性的影响，并与山梨酸类成核剂改性PP的性能进行了比较。实验结果表明，加入脱氢枞酸钾或脱氢枞酸钠后，聚丙烯的雾度大幅度降低，光泽度提高，但透光率变化不大；弯曲模量大幅度提高，而拉伸强度和缺口冲击强度略有下降；球晶尺寸大幅度减小；结晶温度提高，结晶度略有上升。脱氢枞酸盐改性聚丙烯与山梨醇类成核剂改性聚丙烯的性能相当，但脱氢枞酸盐克服了山梨醇类成核剂的缺点，可以作为山梨醇类成核剂的理想替代品。     

熔体挤出-拉伸iPP薄膜的结晶行为和性能

通过挤出-拉伸法分别制备了iPP和β成核剂改性iPP薄膜,研究了β成核剂和拉伸速率对薄膜结晶行为和力学性能的影响。采用二维广角X射线衍射、二维小角X射线散射、差示扫描量热法、扫描电镜(SEM)和拉伸试验对薄膜微观结构和力学性能进行了相关分析测试。结果表明:β成核剂的加入使得iPP薄膜中的晶型发生改变;当β成核剂质量分数为0.2%且拉伸速率为30cm/min时,薄膜内部β晶发生明显支化现象,并且在其内部至少形成了三种不同形貌的β晶;试样的断裂伸长率和韧性均增大;随着拉伸速率的增加,试样中β晶含量减小。     

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。     

β成核剂对抗冲聚丙烯共聚物的结晶和力学性能研究

分别用α晶型成核剂和β晶型成核剂对抗冲聚丙烯共聚物（iPP）的结晶和力学性能进行研究,并用偏光显微镜（POM）、广角X射线衍射仪（WAXD）和差示扫描量热仪（DSC）对其进行了详细的表征。结果表明,α和β成核剂使iPP的起始结晶温度（ton）提高15.3℃和12.7℃,结晶峰温度（tp）提高17℃和13.7℃,结晶速率加快。两种成核剂都能使球晶细化,使结晶更加均匀化、规整化,从而使结晶度增加。α成核剂（TMA-3）使iPP的拉伸强度、冲击强度和断裂伸长率分别提高到23.43MPa、22.27kJ/m2和788%;β成核剂因主要是改变球晶的形态,形成与α球晶完全不同的β晶型,使iPP的拉伸强度、冲击强度和断裂伸长率的提高比α成核剂显著,分别达到24MPa、32.81kJ/m2和861%。     

降冰片烯苄酰胺酸盐对等规聚丙烯力学性能和结晶性能的影响

采用差示扫描量热仪(DSC)和偏光显微镜(POM)考察了降冰片烯苄酰胺酸的不同金属盐在等规聚丙烯(iPP)中的成核效果,并研究了这些成核剂对iPP力学性能和光学性能的影响。结果表明,降冰片烯苄酰胺酸盐对ipp熔融峰值温度和结晶峰值温度的影响规律完全一致,降冰片烯苄酰胺酸钠盐(BHBC11)具有有较好的成核效果,添加浓度在0.2%时可使iPP的拉伸强度提高4.6%,弯曲模量提高18.6%;同时可使iPP的结晶峰值温度提高11.5℃;BHBC11的加入可以显著降低球晶的尺寸并大大缩短结晶时间;应用Caze方法对iPP和BHBC11成核iPP的非等温结晶动力学进行了研究,其Avrami指数都接近4。     

等规聚丙烯与液晶成核剂的共混改性研究

以单丙烯酸酯液晶单体（RLC）为成核剂,通过共混反应法对等规聚丙烯（iPP）进行改性,制备含β晶型的聚丙烯产品（β-iPP）。首先介绍了β-iPP的制备工艺,然后通过偏光显微镜、广角X射线衍射对纯iPP、iPP/RLC共混物的球晶结构进行了分析;最后通过X射线衍射、差示扫描量热分析等测试方法研究共混物的结晶结构、结晶行为和热性能。结果表明,液晶成核剂RLC能够诱导iPP生成β晶型;制备β-iPP的最佳工艺条件是RLC含量为0.5 %（质量分数,下同）,结晶温度为110 ℃;β晶型相比于α晶型处于热力学亚稳态,在升温过程中,会发生β晶向α晶的转变,但较高的升温速率会抑制这一转变。     

取代芳基杂环磷酸金属盐类成核剂在等规聚丙烯中的成核效应

采用DSC考察了2,2′-亚甲基双（4,6-二叔丁基苯基）磷酸的不同金属盐在等规聚丙烯中的成核效应,并研究了这些成核剂对等规聚丙烯力学性能和光学性能的影响.结果表明,一价的取代芳基杂环磷酸金属盐如钠盐、锂盐、钾盐具有很好的成核效果,添加0.2%（质量）的钠盐、锂盐或钾盐,可使聚丙烯的结晶峰温度分别提高13.5、13.6℃和15.0℃,结晶度提高5％左右,结晶速率显著提高;同时可使聚丙烯的拉伸强度提高10％左右,弯曲模量提高30％左右,雾度降低40％左右.而二价的钙盐、镁盐、锌盐和三价的铝盐的成核效果不明显.同时非等温结晶动力学研究表明一价的钠盐、锂盐和钾盐的加入可使聚丙烯的结晶方式发生明显的改变.     

各种羧酸二盐对嵌段共聚聚丙烯的β成核研究

合成了6种己二酸盐、庚二酸盐作为嵌段共聚聚丙烯(PP-B)的成核剂,研究其对PP-B的β成核影响。结果表明,庚二酸钙、庚二酸钡、庚二酸镁均具有明显β成核PP-B的效果,且成核效应由大到小次序为:庚二酸钙、庚二酸钡、庚二酸镁;庚二酸钠是低活性的β成核剂;己二酸盐类中己二酸钠和己二酸钡对PP-B是高效的β-成核剂,二者的成核效果相当。通过差示扫描量热分析(DSC)和力学性能测试表明,当己二酸钠的用量为0.2%(质量分数)时,经β成核改性产物的缺口冲击性能最佳,且KDSC(β晶型相对含量)最大。     

Ionomers: Two formation mechanisms and models

The FT IR spectra for different degrees of neutralization of ionomers based on poly(ethylene–methacrylic acid) copolymer were obtained. They involve the alkali metal ions (such as lithium, sodium, potassium, rubidium, and cesium), the alkaline earth metal ions (such as magnesium, calcium, strontium, and barium), and the transition metal ions (zinc and copper). Through the analysis of these spectra it can be deduced that there are two formation mechanisms and corresponding models for the ionomers: a cluster–multiplet model and a coordinated complex model. Also, it can be seen that the metal cations play an important role in the structure of an ionomer. By comparing the spectra of the metal ionomers at different temperatures as well as the spectra of the metal ionomers before and after water immersion, the existence of the two formation mechanisms and models can be inferred further.     

MOLYBDENUM IN ENAMELS: II,ADHERENCE PRODUCED WITH SOLUBLE AND INSOLUBLE MOLYBDATES*

The experiments made with the molybdates of ammonium, sodium, potassium, lithium, calcium, barium, lead, zinc, cadmium, bismuth, and cerium as mill additions to vitreous enamels are described. The properties of these compounds and their behavior as mill additions with or without the addition of antimony compounds are given, and typical smelter batches and mill batches are also included.     

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     

A novel highly efficient β‐nucleating agent for polypropylene using nano‐CaCO3 as a support

In order to increase the isotactic content of β‐nucleated polypropylene (β‐iPP) and decrease the cost of its production, the investigation and development of novel highly efficient β‐nucleators are important issues. Nano‐CaCO₃ was used as a support to prepare a supported β‐nucleator, nano‐CaCO₃‐supported calcium pimelate. Fourier transform infrared spectral analysis shows that an in situ chemical reaction takes place between nano‐CaCO₃ and pimelic acid. Differential scanning calorimetry results indicate that the crystallization and melting temperatures of β‐phase in supported β‐nucleator‐nucleated iPP are higher than those of calcium pimelate‐nucleated iPP. The β‐nucleating ability of the supported β‐nucleator is little influenced by the cooling rate and crystallization temperature over a wide range. The decreased content of pimelic acid in the supported β‐nucleator slightly decreases the crystallization temperature of iPP but it has no influence on the content of β‐phase in nucleated iPP. A novel supported β‐nucleator has been successfully synthesized via pimelic acid supported on the surface of CaCO₃. The crystallization temperature of iPP and melting temperature of β‐phase in iPP nucleated using the supported β‐nucleator are higher than those of iPP nucleated using calcium pimelate. The concept of a supported nucleator will provide a new way to increase the efficiency of polymer additives and to decrease the amounts of them that need to be used by using nanoparticles as supports. Copyright © 2010 Society of Chemical Industry     

Effects of substituted aromatic heterocyclic phosphate salts on properties,crystallization, and melting behaviors of isotactic polypropylene

Nucleation effects of 2,2′‐methylene‐bis (4,6‐di‐tert‐butylphenyl) phosphate metal salts as a nucleating agent for isotactic polypropylene (iPP) were investigated with differential scanning calorimeter and polarized optical microscope, and their effects on mechanical, optical, and heat resistance properties of iPP were also studied. The results showed that monovalent metal salts of substituted aromatic heterocyclic phosphate such as sodium salt, lithium salt, and potassium salt had a good performance. With 0.2 wt % of sodium salt, lithium salt, or potassium salt incorporated into iPP, the crystallization peak temperature of iPP could be increased by 13.5, 13.6, and 15.0°C, respectively; the mass fraction of crystallinity of iPP could be increased by about 5%; and crystallization rate was enhanced increasingly. Meanwhile the tensile strength and flexural modulus of iPP could be increased by about 10 and 30%, respectively, and the clarity and heat distortion temperature of iPP could also be improved significantly. But bivalent and trivalent metal salts of substituted aromatic heterocyclic phosphate had little effect on properties of iPP. Meanwhile the morphology study showed that the addition of monovalent sodium salt could decrease the spherulite size of iPP significantly. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4868–4874, 2006     

Determination of Potassium in Glass with the Hydrogen Flame Photometer

Use of the hydrogen flame attachment and the Beckman Model DU spectrophotometer to determine potassium in soda-lime and boro-silicate glasses in the order of 0.01 to 2.5% K₂O is described. Data are presented showing the effect of varying concentrations of sodium, calcium, magnesium, barium, zinc, aluminum, and iron on the potassium flame emission. The potassium emission is relatively free from interference effects except from zinc and large amounts of barium. The method is rapid, precise, and accurate to 2% of the K₂O present in the sample.