干燥设备在纳米碳酸钙生产中的应用

纳米碳酸钙的生产过程中，干燥方式的选择是影响产品最终质量和成本的重要因素之一。简单介绍了纳米碳酸钙生产过程中的带式干燥、喷雾干燥和旋转闪蒸干燥等几种干燥方式，重点对桨叶一微粉干燥的工艺流程、设备选型、生产特点等进行了介绍，并对几种干燥方式所存在的优缺点进行了比较。     

我国木材干燥设备制造业概况与存在的问题

介绍了我国木材干燥的市场需求与设备制造企业的概况,指出了我国木材干燥设备制造企业目前存在着技术规范还不够健全、缺乏质量监督机构、检测控制系统精度差、零部件质量差及干燥设备的能耗偏高等问题,并对提高木材干燥设备质量提出了几点建议。     

真空干燥设备的国内外发展动态

真空干燥设备种类较多，应用领域广泛，发展比较迅速。拟就其中几种真空干燥设备的国内外发展动态进行阐述，以求实现信息交流，找出发展真空干燥设备需要解决的难题，提高我国真空干燥设备的技术水平。     

高温热管热风炉在纳米碳酸钙干燥中的应用

对纳米碳酸钙的性质进行了分析，介绍了一种新型换热设备——燃煤型高温热管热风炉，该设备热效率高。能耗低，寿命长，运行可靠，供热稳定，烟尘排放达到了国家环保要求。目前已广泛应用于无机盐和非金属矿产品高温干燥，是纳米碳酸钙干燥的理想热源。     

工业用碳酸钙发展概况

本文综述了工业用碳酸钙近年来在国内外发展情况，对我国氨碱工业在发展碳酸钙产品方面提出一些粗浅看法     

干燥设备的最新进展

介绍了目前常用干燥设备的类型、工作原理、应用及发展趋势,给出了干燥操作的若干节能措施。     

关于国内干燥设备的几个问题

从干燥设备的开发设计、使用、操作及适用范围４个方面论述了干燥设备中所存在的问题,旨在推动干燥行业能以理论来指导生产、使用和操作,并能提高设备的生产能力以及出现通用性强的干燥设备。     

纳米碳酸钙粉体干燥技术现状

简要介绍了纳米碳酸钙工业生产中的烘房干燥、输送带式干燥、盘式干燥、回转圆筒干燥、喷雾干燥、真空耙式干燥、旋转快速干燥等一级干燥技术。讨论了输送带式干燥和旋转快速干燥、桨叶式干燥和旋转快速干燥、桨叶式干燥和微粉干燥、双螺旋输送干燥和盘式干燥等两级组合干燥技术。     

环己酮生产中碳酸钠回收干燥装置的设计与分析

针对环己酮生产过程中废碱碳酸钠回收利用的工艺特点,设计了一种新型干燥装置,对干燥器的干燥流程、干燥器的结构和工作原理进行了分析及计算。结果表明:循环自动干燥碳酸钠设备主要由干燥箱、供热风系统、抽湿系统、扩散系统和包装系统组成;通过温控由电烘箱进行碳酸钠干燥实验,得到了碳酸钠干燥设备的干燥曲线,该系统干燥能力达1～2 t/h,干燥后碳酸钠含水率小于2%;该系统利用工厂废烟气作热源,节省干燥成本,且无环境污染。该设备干燥能力大,热效率高,能耗低,调控性能好,很好的解决了环己酮工业中废碱处理的难题。     

世界碳酸钙工业发展近况

世界碳酸钙工业发展迅速，产能不断增加，首先介绍了近几年来重质研磨碳酸钙（GCC）产业的发展概况，重点介绍了中国、日本、马来西亚、韩国、泰国的GCC产业及国际著名GCC生产公司在中国的经营情况。其次介绍了世界轻质沉淀碳酸钙（PCC）的市场概况及国外大型PCC生产公司的基本情况。最后，重点介绍了中国大陆地区的碳酸钙生产与市场情况，并通过分析近几年中国碳酸钙产品的进出口数量及价格情况指出，开发适合碳酸钙用户需求的新产品、新技术，参与国际竞争是今后中国碳酸钙生产企业的发展方向。     

剖析碳酸钙生产"三合一"工艺及设备选型

剖析了碳酸钙生产的“三合一”工艺。对传统间歇鼓泡碳化工艺进行了创新性的改进,使之不仅可以生产轻质碳酸钙、微细碳酸钙,还可以生产纳米碳酸钙。讨论了碳化过程中的技术关键。通过TEM等手段对实际生产的产品进行了表征,并对设备的选型做出了详细的阐述。对于中小碳酸钙生产企业的钙产品更新换代,适应新材料发展的需求具有一定的指导意义。     

Polypropylene/calcium carbonate nanocomposites

Polypropylene (PP) and calcium carbonate nanocomposites were prepared by melt mixing in a Haake mixer. The average primary particle size of the CaCO₃ nanoparticles was measured to be about 44 nm. The dispersion of the CaCO₃ nanoparticles in PP was good for filler content below 9.2 vol%. Differential scanning calorimetry (DSC) results indicated that the CaCO₃ nanoparticles are a very effective nucleating agent for PP. Tensile tests showed that the modulus of the nanocomposites increased by approximately 85%, while the ultimate stress and strain, as well as yield stress and strain were not much affected by the presence of CaCO₃ nanoparticles. The results of the tensile test can be explained by the presence of the two-counter balancing forces—the reinforcing effect of the CaCO₃ nanoparticles and the decrease in spherulite size of the PP. Izod impact tests suggested that the incorporation of CaCO₃ nanoparticles in PP has significantly increased its impact strength by approximately 300%. J-integral tests showed a dramatic 500% increase in the notched fracture toughness. Micrographs of scanning electron microscopy revealed the absence of spherulitic structure for the PP matrix. In addition, DSC results indicated the presence of a small amount of β phase PP after the addition of the calcium carbonate nanoparticles. We believe that the large number of CaCO₃ nanoparticles can act as stress concentration sites, which can promote cavitation at the particle-polymer boundaries during loading. The cavitation can release the plastic constraints and trigger mass plastic deformation of the matrix, leading to much improved fracture toughness.     

碳酸钙在复合改性中的应用

无机填料碳酸钙在聚丙烯复合体系中的应用,研究了碳酸钙的加入对聚丙烯光学性能、分散性、力学性能中的冲击强度的影响,同时深入分析了无机填料对聚丙烯复合体系的增强增韧机理。     

几种纳米碳酸钙干燥工艺的比较

纳米碳酸钙新产品的干燥 ,目前大多采用烘房烘干、转筒干燥、喷雾烘干、闪蒸干燥、带式烘干等方法。实践比较证明 ,带式干燥工艺能较好地满足纳米级碳酸钙生产的品质、经济性要求 ,是一种比较适宜的工艺     

The toughening mechanism of polypropylene/calcium carbonate nanocomposites

The toughening mechanism of polypropylene (PP) filled with calcium carbonate (CaCO₃) nanoparticles is described. In a previous study (Macromolecule 2008;41:9204), we observed that intensive ligament-stretching following debonding of nanoparticles was responsible for the significant improvement in the impact toughness of the annealed PP/CaCO₃ nanocomposites. Furthermore, we hypothesized that strong ligaments, which have high fracture stresses, are needed to stabilize the crack-initiation process and to increase the energy dissipation in the crack-initiation stage. In this study, we used a high-molecular-weight PP to test this hypothesis because strong ligaments could be created from this high-molecular-weight PP. The notched Izod impact strength of the nanocomposites containing the high-molecular-weight PP and 20 wt% CaCO₃ nanoparticles with a monolayer coating of stearic acid was measured to be about 370 J/m, whereas the impact strength of the unfilled PP was 50 J/m. The size of the plastic deformation zone was found to be dependent on the molecular weight of the PP matrix because the strong ligaments of the high-molecular-weight PP enabled the expansion of the plastic deformation zone, leading to a considerable increase in the impact strength. The synergic effect of the high-molecular-weight PP and the monolayer-coated nanoparticles produced nanocomposites with high impact strength, which is much greater than the inherent impact strength of the unfilled polymer. In addition, the effect of the high-molecular-weight PP on the dispersion of the nanoparticles was investigated.     

Strengthening acrylonitrile-butadiene-styrene (ABS) with nano-sized and micron-sized calcium carbonate

ABS was reinforced by both micron-sized (MCC) and nano-sized precipitated calcium carbonate (NPCC) particles through melt compounding. The MCC/ABS composites were found to have higher modulus but lower tensile and impact strength than neat ABS. In contrast, NPCC increased modulus of ABS whilst maintained or even increased its impact strength for a certain NPCC loading range. SEM examinations revealed that NPCC particles/agglomerates were distributed in much smaller sizes in the composites than its MCC counterparts. The larger interfacial area between NPCC and ABS and cavitation-induced shear yielding in the ligament are believed to be the main reasons of the mechanical property improvement of the NPCC/ABS composites. NPCC/ABS also shows completely different rheological behavior from MCC/ABS, such as the loss of Newtonian region, high G′ at low frequencies and the appearance of yield phenomenon. A NPCC network structure was believed to be formed in the composites and induced these pseudo-solid-like rheological behaviors.     

纳米碳酸钙的生产与现状

本文介绍了纳米碳酸钙的生产、现状及其应用。