Effect of Oleic Acid-modified Nano-CaCO3 on the Crystallization Behavior and Mechanical Properties of Polypropylene

Oleic acid (OA)-modified CaCO3 nanoparticles were prepared using surface modification method. Infrared spectroscopy (IR) was used to investigate the structure of the modified CaCO3 nanoparticles, and the result showed that OA attached to the surface of CaCO3 nanoparticles with the ionic bond. Effect of OA concentration on the dispersion stability of CaCO3 in heptane was also studied, and the result indicated that modified CaCO3 nanoparticles dispersed in heptane more stably than unmodified ones. The optimal proportion of OA to CaCO3 was established. The effect of modified CaCO3 nanoparticles on crystallization behavior of polypropylene (PP) was studied by means of DSC. It was found that CaCO3 significantly increased the crystallization temperature, crystallization degree and crystallization rate of PP, and the addition of modified CaCO3 nanoparticles can lead to the formation of β-crystal PP. Effect of the modified CaCO3 content on mechanical properties of PP/CaCO3 nanocomposites was also studied. The results showed that the modified CaCO3 can effectively improve the mechanical properties of PP. In comparison with PP, the impact strength of PP/CaCO3 nanocomposites increased by about 65% and the flexural strength increased by about 20%.

稀土β晶成核剂改性nano-CaCO3/PP复合材料的结晶行为

讨论了稀土β晶成核剂(WBGⅡ)对nano-CaCO3/PP复合材料结晶性能的影响,并借助WAXD、DSC及PLM对PP、nano-CaCO3/PP和WBGⅡ/nano-CaCO3/PP复合材料的结晶行为及晶体形态进行了表征。结果表明:加入少量WBGⅡ后,聚丙烯基复合材料的晶型和球晶形态发生明显变化,提高了材料的起始结晶温度和结晶温度,降低了材料的过冷度,半结晶期延长。

PPS/GF/Nano-CaCO3三元复合材料的结晶性能

研究了纳米级碳酸钙(Nano-CaCO3)含量及表面处理对玻璃纤维增强聚苯硫醚(PPS/GF)三元复合材料结晶性能的影响。结果表明:随着Nano-CaCO3质量分数(φf)的增加,经硬脂酸和钛酸酯偶联剂作表面处理的PPS/GF/Nano-CaCO3三元复合体系(SI和SII)的起始结晶温度、结晶温度和结晶度均发生了不同的变化。当φf小于4%时,SII复合体系的结晶度最高。

圆管内三角翼涡流发生器CaCO3污垢特性

采用CFD软件模拟研究管内三角翼涡流发生器CaCO3污垢特性,考察涡流发生器排列间距、攻角、翼长及夹角对污垢热阻的影响。结果表明,在涡流发生器翼片两侧产生2个对称的运动方向相反的涡旋,且装有涡流发生器的强化管的污垢热阻小于光管的污垢热阻,说明涡流发生器对壁面边界层的扰动可有效抑制污垢的沉积。渐近污垢热阻随间距的增加而增大,且增速逐渐变缓;渐近污垢热阻在攻角小于90°时,随攻角的增加而增大,在攻角大于90°时,随攻角的增加而减小;渐近污垢热阻随翼长的增加而减小,且减小的速度逐渐增大;渐进污垢热阻随夹角的增加而减小,且减小趋势逐渐变缓。

纳米CaCO3／PP／PS复合材料的结晶与熔融行为

熔融方法制备了纳米CaCO3／PP／PS复合材料，DSC研究了PP／PS、增容PP／PS共混物及其纳米CaCO3填充共混物的结晶与熔融行为。研究结果表明加入PS对PP结晶行为影响不大，但导致PP熔点下降，熔融峰从单峰变为双峰。纳米CaCO3和增容剂对PP／PS共混物中PP结晶存在异相成核作用，提高PP结晶温度和熔点，PP—g—MA和PP—g—AA的异相成核作用比CaCO3的大。PP—g—MA增容的PP／PS共混物和CaCO3填充共混物有利于PP形成β晶，但CaCO3填充共混物、PP—g—AA的增容PP／PS共混物和CaCO3填充共混物无β晶形成。

The Effect of Ionic Liquids on the CaCO_3 Crystal Growth

In this paper, the effect of ionic liquids on the CaCO3 crystal growth has been studied for the first time. The obtained CaCO3 crystals were charactered by the X-ray diffraction and scanning electron micrographs. The results showed that the control ability of ionic liquids for CaCO3 crystals growth was dependent on the counter anion very much.

羧甲基菊粉对CaCO3晶体表面Zeta电位及微观形貌的影响

羧甲基菊粉(CMI)是一种含有羧基(—COOH)的多糖类聚合物,探讨了其作为新型水处理药剂对CaCO3晶体结垢形成的影响。研究了其对CaCO3晶体表面Zeta电位的影响,将等浓度的Ca2+与CO32-的溶液混合,适时测定CaCO3晶体生长过程中表面Zeta电位及溶液中pH的变化。实验结果表明,CaCO3晶体表面带有负电荷,在CaCO3晶体生长过程中加入CMI,对CaCO3晶体表面Zeta电位没有明显影响,使CaCO3溶液pH降低的趋势稍有减缓。并利用扫描电镜(SEM)、X射线衍射(XRD)等分析方法对新生成的CaCO3晶体进行表征,探讨CMI对CaCO3晶体微观形貌的影响。

CaCO3纳米粒子在45#钢表面的摩擦学性能

在Tween-80／C10H21OH／H2O体系层状液晶中合成出平均粒径为30～40nm的CaCO3纳米粒子，用四球磨损试验机考察了CaCO3纳米粒子作为润滑添加剂在Tween-80／C10H21OH／H2O体系层状液晶中的摩擦磨损行为，并用X射线光电子能谱对其抗磨减摩机理进行了研究。研究结果表明：CaCO3纳米粒子能提高Tween-80／C10H21OH／H2O体系层状液晶的摩擦学性能，在摩擦过程中，摩擦表面生成了化学反应膜。

Effect of Oleic Acid-modified Nano-CaCO_3 on the Crystallization Behavior and Mechanical Properties of Polypropylene

Oleic acid OA-modified CaCO3 nanoparticles were prepared using surface modification method. In- frared spectroscopy IR was used to investigate the structure of the modified CaCO3 nanoparticles, and the result showed that OA attached to the surface of CaCO3 nanoparticles with the ionic bond. Effect of OA concentration on the dispersion stability of CaCO3 in heptane was also studied, and the result indicated that modified CaCO3 nanoparticles dispersed in heptane more stably than unmodified ones. The optimal proportion of OA to CaCO3 was established. The effect of modified CaCO3 nanoparticles on crystallization behavior of polypropylene PP was studied by means of DSC. It was found that CaCO3 significantly increased the crystallization temperature, crystal- lization degree and crystallization rate of PP, and the addition of modified CaCO3 nanoparticles can lead to the for- mation of β-crystal PP. Effect of the modified CaCO3 content on mechanical properties of PPCaCO3 nanocompo- sites was also studied. The results showed that the modified CaCO3 can effectively improve the mechanical proper- ties of PP. In comparison with PP, the impact strength of PPCaCO3 nanocomposites increased by about 65% and the flexural strength increased by about 20%.

超细CaCO_3的粒子尺寸对PP结晶行为的影响

The effects of CaCO\-3 on the crystallization behavior of polypropylene (PP) were studied by means of DSC and WAXD.The average sizes of the CaCO\-3 powders used were 0\^1?μm (UC) and 0\^5?μm (GC),respectively.The PP/CaCO\-3 composites at compositions of 1?phr and 10 phr were investigated.The results showed that the addition of CaCO\-3 reduced the supercooling,the rate of nucleation and the overall rate of crystallization (except for the 10?phr UC/PP sample).The crystallinity of PP was increased and the size distribution of the crystallites of α \|PP was broadened.On the other hand,the crystallization rate of 10?phr UC/PP is 1\^5 times higher than that of neat PP.It has an overall rate of crystallization 2 times as much as that of the neat PP and has the maximum crystallinity.The sizes of crystallites and the unit cell parameters of α \|PP were varied by the addition of CaCO\-3. β \|PP was formed by addition of GC and was not detected by addition of UC.The differences of crystallization behaviors of PP might be attributed to the combined effects of the content and size of CaCO\-3 filled.

PP/PA6/nano-CaCO_3三元复合材料的结晶行为

通过应用偏光显微镜、广角X射线衍射、差示扫描量热(DSC)等手段分析和表征了PP/PA6/nano-CaCO3聚丙烯三元复合材料共混体系各组分对其结晶性能的影响。研究发现,PA6、nano-CaCO3对改性聚丙烯复合材料均有诱导成核结晶的作用,加入nano-CaCO3的复合材料的诱导结晶作用要高于加入PA6的复合材料,同时复合材料的结晶温度和结晶速率得到提高。改性后的复合材料结晶度都有不同程度的下降,其中PP/PA6/POE-g-MAH的结晶度为31.83%,PP/PA6/nano-CaCO3/POE-g-MAH的为33.83%。

60℃静态时碳酸钙析晶污垢初始阶段生长机理

以余热利用换热器为研究对象,在60℃CaCl2-Na2CO3溶液中改变浓度、pH值和材料,通过静态反应生长法,采用称重法和扫描电子显微镜分别获得不同浸入时间挂片的结垢量和污垢形貌。结果表明:较高的浓度、pH值和材料表面自由能,会产生较高的晶体生长动力和能量,前者促进细长的柱状或针状晶体形成并提高其生长速率;后者使系统能量降低,促进其他晶相转变为方解石。碳酸钙析晶污垢生长可分为结垢前期(表面反应机理),结垢中期(表面反应机理与颗粒粘附机理竞争期)和结垢后期(颗粒粘附机理)。结垢前期和结垢中期在诱导期内,污垢热阻为负值或零且对流体还没有阻力,而结垢后期则对应生长期,属于污垢快速生长阶段。

P123/SDS水溶液中碳酸钙结晶及形貌的研究

仿生合成是模拟生物矿化合成人工晶体的一种方法。在生物矿化中的无机矿物往住是在有机基质的参与下形成的。它们在有机基质上成核．并且在整个结晶过程中受到有机基质及其他生命活动的调控，因而在晶体的形态、尺寸、以及取向上都具有高度的统一性和有序性．而这些特性又使生物矿化无机材料比一般天然矿物材料具有更优越的性能。在纷繁的有机体系中已经发现了60多种无机矿物．例如在软体动物的贝壳中存在着蛋白质／碳酸钙的杂化材料．这种材料有着很好的机械性能。碳酸钙是一种重要的无机材料，在造纸、橡胶、医药、涂料等领域有着广泛的应用。碳酸钙属ABO3类的多型晶体，有方解石型、文石型、球霰石型，其堆积方式略有区别。

针状纳米级碳酸钙的工业生产与应用

经小试、中试(70t/a装置)、工业化试验(25kt/a工业装置),在自研的多组分结晶导向剂的作用下,较高温度(35～75℃)、较高浓度(7%～12%)碳化工艺条件下合成粒度分布均匀,粒径为10～20nm,长径比为15～20,比表面积≥90m2/g,总孔容≥0.26cm3/g的针状(晶须)纳米碳酸钙。经在乳胶漆、PVC制品中试用,均取得理想效果。文中还给出了10kt/a针状(晶须)纳米级碳酸钙新建与改建设计方案。

几种翼型涡流发生器对CaCO_3污垢特性影响的数值模拟

为研究翼型涡流发生器结构以及布置对换热面污垢的影响,对矩形通道内布置翼型涡流发生器后壁面CaCO3析晶污垢的沉积进行了模拟。计算并分析了在温度为50℃,流速为0.2m·s-1,浓度为1000mg·L-1的CaCO3过饱和溶液下,翼形涡流发生器的翼型、攻角和纵向间距等几何因素对表面污垢沉积的影响。结果表明:表面单位面积结垢量随着翼型涡流发生器攻角的增大而减小,随着涡流发生器列间距的增大而增大,当间距为60mm时达到最大,超过60mm后表面单位面积结垢量呈现下降趋势。

大分子相容剂改性纳米CaCO_3/PP复合材料的非等温结晶行为

熔融混炼制备了4种大分子相容剂改性的纳米CaCO3/PP复合材料,用DSC和WXRD研究了复合材料中PP的结晶与熔融行为。结果表明,纳米CaCO3对PP结晶存在异相成核作用,并诱导PP形成β晶。相容剂丙烯酸接枝聚丙烯(PP-g-AA)和马来酸酐接枝聚丙烯(PP-g-MA)也存在异相成核作用,提高PP结晶温度。PP-g-AA、PP-g-MA和马来酸酐接枝乙烯-辛烯共聚物(POE-g-MA)与纳米CaCO3存在异相成核协同作用,进一步提高PP的结晶和熔融温度,PP-g-MA和POE-g-MA还促使纳米CaCO3诱导PP生成β晶。但马来酸酐接枝乙烯-醋酸乙烯酯共聚物(EVA-g-MA)则阻碍纳米CaCO3对PP的异相成核作用。实验结果表明纳米CaCO3/PP复合材料中PP结晶的异相成核作用与纳米CaCO3/PP界面的相互作用有关,而纳米CaCO3/PP界面的相互作用与相容剂的结构有关。

纳米碳酸钙改性聚丙烯的结晶行为

采用DSC、WAXD及偏光显微镜(PLM)对纳米CaCO_3改性PP的等温结晶、等速降温结晶过程及熔融行为进行了研究。结果表明:纳米CaCO_3对聚丙烯的结晶成核有诱导作用,增加了β晶含量,提高了聚丙烯的冲击韧性。

光电催化降解印染废水的羟基自由基机理研究

光电协同催化的主要作用原理为羟基自由基机理,但羟基自由基的分析较为困难。以水杨酸为分子探针,以分光光度法对光电协同催化处理印染废水过程中的羟基自由基进行测定,通过改变光照时间、光照强度、外加电压和pH进行试验。结果表明,光电催化降解酸性紫红比单独的光催化和电催化效果好;.OH是酸性紫红降解的主要因素。水杨酸分子探针浓度升高时,酸性紫红的脱色率相应减少;一定的光照时间内.OH生成量与时间成正比关系;光照强度增大,羟基自由基产生量也相应增加;外加电压10 V,pH为6～8时.OH有较高的生成量。

PA6／无机纳米复合材料的力学性能研究

通过熔融共混法制备了尼龙6(PA6)/SiO2包覆纳米CaCO3、PA6纳/米SiO2、PA6纳/米CaCO3复合材料,对其力学性能进行比较分析研究。结果表明,3种纳米复合体系的力学性能与纯PA6相比都有不同程度的提高。三者相比较,PA6/SiO2包覆纳米CaCO3体系的力学综合性能最优,当SiO2包覆纳米CaCO3的添加量为0.5份时,缺口冲击强度提高了13%,断裂伸长率提高了169%,拉伸强度和弯曲弹性模量也有所提高。另外,差示扫描量热法(DSC)研究发现,无机纳米粒子对PA6的结晶性能影响不大。

磁场对碳酸钙结晶过程及晶型影响的研究

通过测定电导率变化研究了磁场对碳酸钙结晶过程的影响,利用扫描电子显微镜(SEM)和X射线衍射仪(XRD)对碳酸钙晶型进行了表征。结果表明,当Ca2+浓度低于2.5 mmol/L时,磁处理抑制碳酸钙的结晶速度;当Ca2+浓度高于2.5 mmol/L时,磁处理促进了碳酸钙的结晶速度且抑制了晶粒的长大。随着磁场强度的增大,磁处理对碳酸钙结晶的影响更明显。