成核剂二-(3,4-二甲基苄叉)山梨醇在聚丙烯中的成核效应

研究成核剂二-(3,4-二甲基苄叉)山梨醇(DMDBS)对等规聚丙烯力学性能、光学性能和结晶行为的影响.结果表明:DMDBS可以大幅度提高聚丙烯的力学性能、光学性能和结晶峰温度,具有很好的成核性能.当成核剂DMDBS添加浓度为0.2%时,与空白聚丙烯相比,成核聚丙烯的拉伸强度和弯曲模量可分别提高7.46%和11.96%,雾度可降低52.32%,结晶峰温度T_c可从119℃左右提高到130℃左右.同时,DMDBS的加入可大幅度降低聚丙烯的球晶尺寸.     

木糖醇醛类化合物对聚乙烯结晶结构及性能的影响

分别以木糖醇与对甲基苯甲醛、3,4-二甲基苯甲醛、对乙基苯甲醛为合成原料,利用缩醛反应机理,合成了3种不同的木糖醇醛类化合物,包括1,3-2,4-二亚(对甲基)苄基木糖醇(MDBX)、1,3-2,4-二亚(对乙基)苄基木糖醇(EDBX)、二(3,4-二甲基二苄叉)木糖醇(DMDBX).使用溶液沉淀法制备含有0.3%(质量分数)DMDBX、EDBX、MDBX的聚乙烯(PE)粉末样品.采用X衍射仪、红外光谱仪、偏光显微镜、差示扫描量热仪研究样品的结晶结构和结晶性质.结果表明该类木糖醇醛化合物能够促进PE的异相成核,减小PE球晶尺寸,提高PE结晶度,可以作为PE的结晶成核剂.根据Avrami模型,采用Kissinger方程计算了动力学数据.该类成核剂能提高PE的结晶速率,降低活化能.DMDBX成核结晶效果最明显,EDBX其次,MDBX最小.     

复合成核剂对聚丙烯物理力学性能的影响

研究了1,3:2,4-二(对甲基二苄叉)山梨醇/1,3:2,4-二(3,4-二甲基二苄叉)山梨醇(MDBS/DMDBS)复合成核剂、DMDBS/2,2'-亚甲基-二(4,6-二叔丁基苯酚)磷酸盐(NA-1)复合成核剂、NA-1/2,2'-亚甲基-双(2,4-二叔丁基苯酚)磷酸盐(NA-2)复合成核剂的协同效应对聚丙烯(PP)透明性及力学性能的影响。结果表明:当MDBS与DMDBS的复配比为0.15:0.10时,改性PP的雾度达到最小值9.6%;当DMDBS与NA-1的复配比为0.20:0.05时,改性PP的雾度达到最小值10.3%。此外,NA-1的加入提高了PP的弯曲强度和弯曲模量;NA-1/NA-2复合成核剂对PP透明性的改善效果不明显,但能使PP的弯曲模量显著提升,最高可达1.96 GPa。     

山梨醇衍生物对聚乙烯结晶行为的影响

分别以山梨醇与对甲基苯甲醛、对乙基苯甲醛、3,4-二甲基苯甲醛为原料,利用缩醛反应机理,合成出3种不同的山梨醇衍生物——1,3-2,4-二亚(对甲基)苄基山梨醇(MDBS)、1,3-2,4-二亚(对乙基)苄基山梨醇(EDBS)、二(3,4-二甲基二苄叉)山梨醇(DMDBS)。使用溶液沉淀法制备含DMDBS、EDBS、MDBS质量分数分别为0.3%的3种粉末聚乙烯(PE)样品;采用X衍射仪、红外光谱仪、偏光显微镜、差示扫描量热仪对其进行了结晶结构及性质考察;用Avrami模型、Kissinger方程计算了各PE样品的结晶动力学参数。结果表明,山梨醇衍生物没有改变PE的晶体结构,保持了PE晶体的稳定性,提高了成核密度,使PE球晶尺寸由65μm平均降至53μm。动力学数据表明,山梨醇衍生物能提高PE的结晶速率,降低结晶活化能,PE的Avrami指数由4减小至3~3.6。在添加量相同的条件下,DMDBS、EDBS和MDBS可分别令PE结晶度提高4.83%、4.42%、1.25%。DMDBS对PE的改性效果最明显,EDBS次之,MDBS最小。     

DBS类凝胶因子的合成及性能

以取代的苯甲醛和山梨醇为原料,环己烷为溶剂和夹带剂,甲醇为促进剂,对甲苯磺酸为催化剂,用共沸脱水法合成了1,3∶2,4-O-二苄叉-D-山梨醇(DBS),收率91.2%;1,3∶2,4-O-二(4-甲基苄叉)-D-山梨醇(MDBS),收率90.5%;1,3∶2,4-O-二(3,4-二甲基苄叉)-D-山梨醇(DMDBS),收率89.0%。用原甲酸三甲酯作化学脱水剂,合成了1,3∶2,4-O-二(2,4,6-三甲基苄叉)-D-山梨醇(2,4,6-TMDBS),收率37.1%;1,3∶2,4-O-二(2,4,5-三甲基苄叉)-D-山梨醇(2,4,5-TMDBS),收率30.9%;1,3∶2,4-O-二(5,6,7,8-四氢萘-2-亚甲叉)-D-山梨醇(DTHNS),收率74.1%。其结构经1HNMR确认。测定了它们对21种有机溶剂的凝胶性能。发现苯环上取代基的位置、数量、大小等因素对凝胶性能有重要影响。2,4,6-TMDBS无凝胶性能,其余化合物对多种溶剂具有良好的凝胶性能,DTHNS对非极性化合物有极优良的凝胶性能。测试并比较了上述化合物的最低凝胶浓度,证实了凝胶-溶胶解缔温度随凝胶因子质量分数增加而增加;随着溶剂(一元直链伯醇)碳原子数的增加而增加。     

成核剂二(3,4-二甲基二苄叉)山梨醇对聚丙烯结晶性能的影响

以二(3,4-二甲基二苄叉)山梨醇(DMDBS)为成核剂,使用溶液沉淀法制备 DMDBS 质量分数分别为0.1%、0.3%、0.5%、0.7%、0.9%的粉末聚丙烯(PP)样品,采用红外光谱仪、差示扫描量热仪,X 衍射仪和偏光显微镜等技术进行结晶性能的研究。结果表明,透明成核剂 DMDBS 是 PP 的有效α诱导剂,DMDBS 的加入能诱导大量球晶生成,使结晶峰尖锐,结晶温度区间变窄,提高 PP 的结晶速率和结晶度,其中熔融吸收峰温度提高1.7～3.1℃,结晶度提高16%左右。在 PP 中添加0.3%DMDBS 时,PP 的改性效果最好,结晶度达到最大值。     

透明聚丙烯的结晶行为

采用差示扫描量热仪、偏光显微镜和X射线衍射仪等研究了透明成核剂和透明聚丙烯的结晶行为和结晶形态。结果表明:山梨醇类透明成核剂第二次升温比第一次升温熔融温度下降10~50℃,熔融焓下降50%~90%;纯聚丙烯结晶温度约为110℃,熔融温度约为152℃,球晶尺寸约50μm,晶型为α晶;加入透明成核剂后,聚丙烯的结晶温度升高约10℃,熔融温度升高约3℃,晶粒尺寸约1μm,晶型仍为α晶。     

成核剂对共聚甲醛MC90结晶与力学性能的影响

利用差示扫描量热仪、偏光显微镜和万能材料试验机等研究了不同成核剂用量对聚甲醛MC90的结晶行为和力学性能的影响。结果表明,成核剂的加入可有效减小POM的球晶尺寸,提高POM的结晶温度和缺口冲击强度。当成核剂添加量为0.8%时,最大结晶温度由139.2℃提高到143.3℃,球晶平均尺寸约60μm,为未加成核剂的POM球晶尺寸的1/2,缺口冲击强度由5.5k J·m~(-2)增加到6.1k J·m~(-2)。     

二苄叉山梨醇衍生物对PP/OBC共混材料的影响

以均聚聚丙烯(PP)为原料,乙烯-辛烯嵌段共聚物(OBC)为增韧材料,二苄叉山梨醇衍生物(YS-688)为成核剂,采用双螺杆挤出和注塑成型方法制备PP/OBC共混材料,用DSC、WAXD和POM分析了YS-688对PP/OBC共混材料结晶性能、晶型和晶体形态的影响,测试了共混材料的力学性能。结果表明:随着YS-688含量的增加,PP/OBC共混材料的缺口冲击强度呈先上升后下降趋势,拉伸强度和弯曲强度有所提高;含3.0%YS-688母粒的PP/OBC共混材料,与纯PP相比,熔融温度降低了2.32℃,结晶温度提高了12.30℃,α晶型的衍射峰强度增大,PP球晶尺寸减小,缺口冲击强度提高了204.23%,韧性较大幅度提高。     

成核剂YS-688改性抗菌PP薄膜的研究

以聚丙烯（PP）为基体树脂,改性载银磷酸锆为抗菌剂,YS-688（二苄叉山梨醇衍生物）为成核剂,制备抗菌剂母粒、成核剂母粒和抗菌PP薄膜,研究了成核剂改性抗菌PP薄膜性能。结果表明：经YS-688改性的抗菌PP薄膜,球晶尺寸减小,结晶密度增大,结晶温度提高;含0．9％改性载银磷酸锆和0.3％YS-688的PP薄膜,其拉伸强度（纵向／横向）51．16／31．88MPa,透光率88．8％,雾度2．9％,对金黄色葡萄球菌和大肠杆菌抗菌率为99．26％和99．57％,物理力学性能和抗菌性能优良。     

挤出裂解工艺对聚乙烯蜡性能的影响

以单螺杆挤出机为裂解设备,聚乙烯951-050及2426 H为裂解原料,制备了聚乙烯蜡(PEW)产品,研究了聚乙烯蜡黏均分子量和熔点随螺杆的转速、裂解温度的变化规律,分析了氮气保护以及冷却工艺对聚乙烯蜡性能的影响。结果表明,聚乙烯蜡的熔点和黏均分子量均随着螺杆转速的增加而增加,随着裂解温度的增加而降低。在较高的螺杆转速内,裂解温度对聚乙烯蜡产物熔点的变化影响较小。当空气存在的条件下,聚乙烯裂解程度加深,产物颜色加深;相对于自然冷却法,聚乙烯蜡喷粉法降低了聚乙烯蜡的结晶能力,使聚乙烯蜡熔点降低。     

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.     

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     

PEW-g-MAH的制备及其对PP/Talc的改性

由线型低密度聚乙烯裂解反应制备了低相对分子质量聚乙烯蜡，考察了工艺条件的影响因素。得出了反应温度、反应时间与相对分子质量、熔点、软化点之间的关系。在锅中用熔融接枝法制备马来酸酐接枝聚乙烯蜡，研究了反应时间、温度、引发剂和马来酸酐用量对产物接枝率、接枝效率的影响。结果表明在引发剂质量分数0．1％、马来酸酐质量分数4％、反应温度150℃、反应时间3h的条件下，聚乙烯蜡的接枝率达到1.49％。接枝的聚乙烯蜡可作为一种新型偶联剂用于改性聚丙烯与填料复合材料的力学性能，使改性后的聚丙烯复合材料的悬臂粱缺口冲击强度提高了50％。     

Dilatometric investigations of fatty acid methyl esters

Summary The coefficients of expansion and melting dilations were measured for methyl palmitate, methyl stearate, methyl arachidate, methyl behenate, and methyl oleate. The dilatometric curve for the heating cycle of methyl palmitate and methyl stearate in the solid state was composed of a linear section to 49 degrees below the melting point, followed by a curvilinear section to the melting point. The heating and cooling cycle curves for methyl palmitate show the same volume change from −38°C. to 29°C., but the shape of the curves is different. The same relation holds for methyl stearate from −38°C. to 37.5°C. “After-contractions” were found in volume measurements within a few degrees of the melting point of both esters. Equilibrated points were found within 0.5 degrees of the final melting temperature of methyl stearate. A striking similarity exists between curves for variation of the dielectric constant with temperature for long chain linear molecules and the dilatometric data. Presented at the fall meeting, American Oil Chemists' Society, Mnneapolis, Minn., October 11, 1954. Issued as Paper No. 196 on the “Uses of Plant Products” and as N.R.C. No. 3671.     

Effect of zinc stearate on the rheology of ionic elastomer based on carboxylated nitrile rubber

Monsanto rheometry, melt viscometry, differential scanning calorimetry, and dynamic mechanical spectroscopy have been used to study the effects of zinc stearate on the rheological behavior of ionomer based on carboxylated nitrile rubber (XNBR) - zinc oxide (ZnO) system. At temperatures below its melting point, zinc stearate functions as a reinforcing agent for ionomer formation. Above its melting point, it acts as a plasticizer for the ionic domains, thereby facilitating easy processing of the ionomer.     

Phase behavior of homologous series of monoesters of polyols

Phase behavior of anhydrous monopalmitates and stearates and of most laurates, myristates and behenates of ethylene glycol, erythritol, xylitol, sorbitol, and mannitol has been studied. The compounds, substantially free of diesters, are mostly not isomerically pure but are predominantly primary esters. Also studied were the (nonisomeric) palmitate and stearate of pentaerythritol (Pe) and the oleate of erythritol. Mesomorphism, absent in anhydrous monoglycerides unless of short chain length and symmetrical, is a prominent feature of the members of the present group of compounds containing at least three unesterified hydroxyls. In general, crystal melting points rise with length of polyol, and mesomorphic melting points rise faster. Crystal melting points rise with acyl chain length while mesomorphic melting points run through a maximum. Heats of fusion are of the order 40 cal/g for crystal melting and 0.5 cal/g for melting of mesomorphic states. In the range explored, mesomorphic values fall with both polyol length and acyl length. At higher acyl chain length, notably with behenates, there are new features of mesomorphic behavior. Crystalline phase, from solvent, melts to a neat or lamellar phase, which in turn melts to liquid with subsequent appearance of higher melting middle or cylindrical phase. Polymorphism is general among the crystal states and tends to be complex. In a brief study of solvent crystallized 50–50 binary mixes of xylitol stearate with other xylitol esters and other stearates, considerable evidence of solid solution in Form I crystals (of xylitol stearate type) was observed with very modest eutectic lowering of crystal melting point. Mesomorphic points were almost linearly intermediate between those of components. Of particular interest were mixtures of xylitol stearate and 1-monostearin (50–50 and 25–75), for which mesomorphic melting points were realized, and for which an extrapolation to 100% monostearin leads to a hypothetical mesomorphic melting point far below any monoglyceride crystalline melting point. A brief examination of an aqueous xylitol palmitate system explored to a maximum temperature of 165 C shows extensive occurrence of aqueous mesomorphic state somewhat after the manner of monoglyceride systems. Mesomorphic melting level rises rapidly from the value for anhydrous ester.     

Temperature modulated DSC studies of melting and recrystallization in poly (oxy‐1,4‐phenyleneoxy‐1,4‐phenylenecarbonyl‐1,4‐phenylene) (PEEK)

The thermal and crystal morphological properties of amorphous and melt crystallized poly(oxy‐1,4‐phenyleneoxy‐1,4‐phenylenecarbonyl‐1,4‐phenylene) (PEEK) were investigated. Two different molecular weights were studied by Temperature Modulated DSC (TMDSC) over a broad range of annealing times and temperatures. The lower molecular weight PEEK under all crystallization conditions was found to exhibit secondary crystal melting in the low endotherm region, followed by melting of primary crystals melting in the low endotherm region, followed by melting of primary crystals superimposed with a large recrystallization contribution. Primary crystal melting broadly overlapped with melting of the recrystallized species and contributed to the broad highest endotherm. Recrystallization contributions and the interpretation of TMDSC were partially confirmed by independent rapid heating rate melting point determinations and variable heating rate DSC. The higher molecular weight PEEK showed many similarities but generally had smaller levels of reorganization above the annealing temperature under most higher temperature crystallization conditions. TMDSC provides excellent resolution of recrystallization and related events compared to standard DSC. The broad and substantial exothermic recrystallization in amorphous samples was also examined, showing that recrystallization continues through the final melting region.     

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     

乙烯/乙酸乙烯酯/甲基丙烯酸离聚体的合成、表征及性能

以乙烯/乙酸乙烯酯/甲基丙烯酸三元嵌段聚合物为基体合成了它的钠、锌盐离聚体。通过FT IR谱图以及DSC、TGA曲线证明了钠、锌离子与甲基丙烯酸发生了反应,玻璃化温度、熔点有提高;同时经过力学性能测试表明合成的离聚体在力学性能方面有改进。硬脂酸锌是离聚体的有效增塑、增强剂,离聚体的拉伸强度随着硬脂酸锌用量的增加而增加,其最大用量为30%。