不同改性剂对聚丙烯/碳酸钙复合材料性能的影响

以马来酸酐(MAH)、聚丙烯蜡(PPW)为主要原料,采用原位固相接枝改性法制得PP/CaCO3-MAH-PPW复合材料,并与添加相容剂聚丙烯接枝马来酸酐(PP-g-MAH)所制得的PP/PP-g-MAH/CaCO3复合材料进行比较。结果表明,CaCO3良好的分散性及其与PP基体适宜的界面粘接是复合材料具有较好韧性的关键因素。与PP/PP-g-MAH/CaCO3复合材料相比,PP/CaCO3-MAH-PPW复合材料表现出更佳的冲击、弯曲和加工性能,当m(PP)∶m(CaCO3)=100∶20时,材料缺口冲击强度达到最大值,是基体树脂的1.19倍。     

碳酸钙纳米颗粒复合超分子凝胶润滑剂的摩擦学性能研究

采用碳酸钙纳米颗粒与全氟聚醚型超分子凝胶复合得到了一种新型的纳米颗粒复合超分子凝胶润滑剂. 超分子凝胶具有错综复杂的网络结构,有效地提高了碳酸钙纳米颗粒在全氟聚醚润滑油中的分散稳定性. 此外,碳酸钙纳米颗粒作为添加剂极大地提高了超分子凝胶的润滑性能,使其表现出较好的耐高温性能,以及较高的承载力. 采用差式扫描量热仪、热重分析仪和流变分析仪对该复合润滑剂的热力学性能进行表征,结果显示该复合润滑剂具有很好的热稳定性以及较好的力学性能. 最后,通过X射线光电子能谱(XPS)对其摩擦机理进行表征,结果表明碳酸钙纳米颗粒复合超分子凝胶润滑剂优异的摩擦学性能可归因于碳酸钙纳米颗粒在摩擦副表面形成了易剪切的薄膜,以及小尺寸的纳米粒子在摩擦过程中对摩擦表面进行的自修复效应.      

Formation Process and Thermodynamic Poperties of Calcite

The fast mixing of aqueous solutions of calcium chloride and sodium carbonate resulted in crystalline forms of vaterite and calcite under vigorous stirring. Then, the vaterite was transformed to pure calcite within about 180 rain. The crystalline forms all grew with experimental time increase. Scanning electron microscopy （SEM）, Fourier transform infrared spectroscopy （FT-IR）, and X-ray diffraction spectroscopy （XRD） techniques were employed to characterize the as-prepared samples. The heat capacity of the stable as-synthesized calcite was determined by means of an adiabatic calorimeter from 80 to 390 K. The thermodynamic functions of the calcite were derived based on the relationships among the thermodynamic functions and the function of the measured heat capacity with respect to temperature.     

Nano CaCO3:An Unique Condensation Agent for the Preparation of Monosubstituted Calix[4] arene by Ring-opening Reaction

Nano CaCO3 was used as a condensation agent in the ring-opening reaction of p-tert-butylcalix[4] arene with epichlorohydrin to afford 5,11,17,23-tetra-tert-butyl1-26,27,28-trihydroxy-25-(1′-chloro-2′-hydroxy-3′-propyl)calix(4] arene regioselectively in 52% yield,The yield was less than 2% by using normal CaCO3 instead of nano one under the same conditions.     

电石渣可控制备多晶型、多形貌纳米碳酸钙的研究进展

碳酸钙有不同的晶体特征，使其在各个领域发挥不同的作用，对碳酸钙晶型、形貌和尺寸的控制是无机材料制备的研究热点。以电石渣为原料制备纳米碳酸钙能够实现变废为宝，是含钙固废综合利用的研究方向之一。因此在电石渣制备纳米碳酸钙过程中同步实现晶型、形貌的调控，能够将低附加值的电石渣固废转化为高附加值的纳米碳酸钙产品，具有良好的环境效应和经济效益。本文总结了电石渣制备纳米碳酸钙的方法，重点讨论了制备过程中晶型和形貌控制方面的研究进展。结果表明，在碳酸钙晶体成核和生长的过程中，控制工艺条件可以通过影响过饱和度进一步实现对晶型和形貌的调控，且不同种类的添加剂作用机理也不尽相同。热力学、动力学作为控制结晶各过程平衡的基础，可以用来解释各影响因素的作用机理。     

水热条件下黄磷炉渣废料制备碳酸钙晶须

本文采用黄磷炉渣制备白炭黑后的残留废液为原料,尿素作为沉淀剂制备碳酸钙晶须,系统研究了晶型控制剂(MgCl2)的浓度、反应温度、反应时间、尿素和残留废液的体积比等因素对碳酸钙晶须形貌和物相组成的影响,所得产品通过X射线衍射、扫描电镜进行了分析与表征.研究结果表明,反应温度140℃,反应时间3 h,(NH2)2CO:CaCl2体积比为1:3,晶型控制剂为0.3 mol/L的条件之下,可获得平均长度在50 p.m,长径比为10左右的碳酸钙晶须.     

Novel synthesis with an atomized microemulsion technique and characterization of nano-calcium carbonate （CaCO3）/poly（methyl methacrylate） core-shell nanoparticles

The synthesis of hard-core/soft-shell calcium carbonate （CaCO3）/poly（methyl methacrylate） （PMMA） hybrid structured nanoparticles （〈100nm） by an atomized microemulsion polymerization process is reported. The polymer chains were anchored onto the surface of nano-CaCO3 through use of a cou- pling agent, triethoxyvinyl silane （TEVS）. Ammonium persulfate （APS）, sodium dodecyl sulfate （SDS） and n-pentanol were used as the initiator, surfactant and cosurfactant, respectively. The polymeriza- tion mechanism of the core-shell latex particles is discussed. The encapsulation of nano-CaCO3 by PMMA was confirmed using a transmission electron microscope （TEM）. The grafting percentage of the core-shell particles was investigated by thermogravimetric analysis （TGA）. The nano-CaCO3/PMMA core-shell par- ticles were characterized by Fourier transform infrared （FTIR） spectroscopy and differential scanning calorimetry （DSC）. The FTIR results revealed the existence of a strong interaction at the interface of the nano-CaCO3 particle and the PMMA, which implies that the polymer chains were successfully grafted onto the surface of the nano-CaCO3 particles through the link of the coupling agent, In addition, the TGA and DSC results indicated an enhancement of the thermal stability of the core-shell materials compared with that of the pure nano-PMMA, The nano-CaCO3/PMMA particles were blended into a polypropylene （PP） matrix by melt processing. It can also be observed using scanning electron microscopy （SEM） that the PMMA chains grafted onto the CaCO3 nanoparticles interfere with the aggregation of CaCO3 in the polymer matrix （PP matrix） and thus improve the compatibility of the CaCO3 nanoparticles with the PP matrix.     

聚对苯二甲酸乙二醇酯/碳酸钙纳米复合材料的制备和表征

以聚乙二醇磷酸酯1000为表面处理剂, 采用碳化法合成了方解石型碳酸钙纳米粒子, 进一步制备了聚对苯二甲酸乙二醇酯/碳酸钙纳米复合材料. 采用透射电子显微镜(TEM)、 X射线衍射(XRD)、 傅里叶变换红外光谱(FTIR), 场发射扫描电子显微镜(FESEM)和热重分析(TGA)对样品进行了分析. 结果表明, 聚乙二醇磷酸酯1000成功地修饰到碳酸钙的表面, 并得到平均直径为60 nm, 形貌为立方体的纳米碳酸钙晶体. 与碳酸钙(空白)样品相比, 表面处理碳酸钙的复合材料表现出更好的分散性和热稳定性. 采用Friedman方法计算了复合材料热分解的活化能. 聚对苯二甲酸乙二醇酯、 聚对苯二甲酸乙二醇酯/空白碳酸钙和聚对苯二甲酸乙二醇酯/表面处理碳酸钙的活化能分别为200.58, 214.86和219.50 kJ/mol, 进一步说明了表面处理碳酸钙更好地改善了聚对苯二甲酸乙二醇酯的热稳定性.     

超声辅助的荔枝状球霰石的制备与表征

碳酸钙材料的制备过程中的形貌和物相控制对其进一步的工业应用至关重要.本文通过超声空化辅助技术在乙二醇/水溶液中合成了荔枝状的纯相球霰石微球.采用X-射线衍射(XRD)、傅里叶变换红外光谱(FTIR)以及场发射扫描电镜(FESEM)等对合成的试样进行了表征.结果表明,碳酸钙材料的物相组成和形貌与溶液中乙二醇的体积含量以及超声时间密切相关.