Application of ANOVA to image analysis results of talc particles produced by different milling

This study presents statistical evaluation of the shape parameters for different mill products of talc mineral using Clemex image analysis system. The aim of this study was to determine whether the image parameters of the three different mill products were statistically different from each other or not. Image analysis of talc particles ground by laboratory size ball, rod and autogenous mills was performed with a Nikon SMZ 800 stereoscopic zoom microscope and a Clemex PE image analysis system. A total of 446 particles were measured by image analysis for these three different mill products. The shape data such as area, perimeter, convex perimeter, sphericity and roughness were compared by applying one way ANOVA (analysis of variance) method followed by post hoc Tukey's test using the software SPSS (Statistical Package for Social Science) with a .05 significance level. Multiple comparison tests revealed that, the difference between the image data group for different mill products are significant with a 95% confidence level. Finally, autogenous mill products had the highest sphericity and the smoothness among the ball and rod mill products due to its abrasion effect on talc mineral studied. On the other hand, the roughest and most elongated particles of talc mineral studied were obtained by rod milling.     

Studies on Formation and Recrystallization of Intermediate Reaction Products in the System Magnesia-Silica-Water

Mixtures of magnesia and silicic acid ranging in composition from 0.5 to 2.0 M/S were treated hydrothermally at temperatures of 75° to 350°C. for various periods of time. The reaction solids were examined by differential thermal analysis, X ray, and electron microscopy and analyzed chemically. The intermediate products of reaction ranging in composition between that of talc (0.75 M/S) and chrysotile (1.5 M/S) comprised a continuous series of cryptocrystalline needle-like crystaIs matted tightly together and showing the same X-ray pattern. The initial reaction product of the 0.75 to 1.50 M/S raw mixtures was a cryptocrystalline solid having a 1.5 M/S ratio. This phase subsequently reacted with the residual silica, so long as any was available, to form a solid having the composition of the raw mix, but only at relatively moderate temperatures(100°to175°C.). As the temperature was increased the crystals of the 0.75 and 1.50 M/S compositions increased in size, but all remained submicroscopic. The compositions intermediate between 0.75 and 1.5 M/S crystallized as mixtures of talc and chrysotilelike products. The chrysotilelike product appeared as minute needles which did not possess any apparent flexibility.     

改性滑石粉对防化肥结块效果的影响

研究硬脂酸、铝酸酯、钛酸酯对滑石粉的改性效果,以活化指数和接触角作为表征指标,得到滑石粉的较好的改性工艺参数:硬脂酸、钛酸酯、铝酸酯的用量分别为3%、2.5%、3%,改性时间为1.5 h,改性温度为65 ℃.分别利用粒度分析和扫描电镜观察改性前后滑石粉的粒度和形貌,发现改性滑石粉粒径减小,分散性提高.放置42 d后,未添加滑石粉的尿素和复合肥的结块率分别为26.79%和12.96%,结块强度分别为868.38 N/kg和1974.11 N/kg;添加3%钛酸酯改性的滑石粉作为防结块剂时,尿素和复合肥的结块率分别0.59%和0.46%,结块强度分别为30 N/kg和40 N/kg.     

Effect of talc/MMA in situ polymerization on mechanical properties of PVC‐matrix composites

In this study, polymethyl methacrylate (PMMA)‐coated talc was produced by the in situ polymerization of methyl methacrylate on the talc surface. The polymerization reaction was performed by both batch and semicontinuous emulsion processes. The polymerization kinetics, particle size and distribution, grafting efficiency, and coated‐talc morphology were systematically investigated. It was found that the talc particles have no effect on the polymerization of PMMA. The PMMA produced was found to cover the talc surface well. However, only a small amount can be grafted onto the talc. The size distribution of talc particles treated by semicontinuous emulsion polymerization is more uniform than by batch polymerization. The treated talc was subsequently used as filler in a poly(vinyl chloride) (PVC) matrix, and mechanical properties of the PMMA‐coated‐talc/PVC composites were studied. Morphological structure of PVC‐matrix composites revealed that the PMMA coating on talc improved the dispersion of talc in the PVC matrix and enhanced the interfacial adhesion between the talc and PVC. The mechanical properties of the composites, especially the impact strength, were found to be improved. There appears to be a critical covering thickness of PMMA on the talc surface for optimum toughening. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2105–2112, 2001     

Transesterification of Canola Oil to Biodiesel Using CaO/Talc Nanopowder as a Mixed Oxide Catalyst

A series of heterogeneous catalysts including different molar ratios of CaO/talc was synthesized to study the transesterification reaction of canola oil and methanol under different reaction conditions. Characterization and kinetic results revealed that the activity of this catalyst was enhanced due to the increase of CaO/talc molar ratio value leading to an improvement in the biodiesel production. Moreover, the effect of various parameters on the activity of the undertaken catalysts was studied in order to determine the optimum process conditions. Leaching measurements and the durability of the CaO/talc catalyst under several reaction cycles were evaluated and proved it to be a stable catalyst.     

食品接触聚乳酸杯盖中的滑石粉迁移分析

采用国标方法对食品接触聚乳酸（PLA）杯盖进行了总迁移测试，利用原子吸收光谱法对其食品模拟液中滑石粉的迁移量进行了检测，同时采用傅里叶红外光谱法对迁移物蒸发残渣中的滑石粉进行了定性鉴定，并探讨了滑石粉在食品接触材料中的安全性问题。结果表明，本方法准确、快速、简便，可用于食品接触材料中滑石粉的快速鉴别和安全性评价；滑石粉在食品模拟液中不易迁出，因此当PLA制品与食品接触时，其中的滑石粉迁移至食品的风险较低。     

Formation of Expandable Mica from Talc Using the Intercalation Procedure

To investigate the transformation process from talc to expandable micas, mixtures of talc and Na₂SiF₆ were heated from 600° to 900°C and air-quenched at 50°C intervals. The air-quenched product at 800°C mainly consisted of expandable micas with a basal spacing of 1.25 nm, nonexpandable materials with a basal spacing of 0.96 nm, and a small amount of talc used as the starting material. A lattice fringe image by HRTEM of the product shows that the layer spacing at the edges surfaces is about 1.2 nm, but the layer spacing inside of the particles is close to that of talc. Such a nanostructure indicates a topotactic reaction from talc to expandable micas and confirms that Na⁺ ions intercalate into the structure from the edge to the core.     

Fast crystallization of poly(3‐hydroxybutyrate) and poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) with talc and boron nitride as nucleating agents

The crystallization behavior of poly(3‐hydroxybutyrate) (PHB) and poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV) induced by two kinds of nucleating agents, boron nitride (BN) and talc, was investigated by differential scanning calorimetry, polarized optical microscopy and X‐ray diffraction. Both BN and talc have good nucleating ability in the crystallization of PHB and PHBV. From these results, combined with molecular weight measurement by gel permeation chromatography, the mechanism of nucleation by BN and talc in the crystallization of PHB and PHBV has been proposed. BN acts as a nucleating agent itself and initiates nucleation in the crystallization of PHB and PHBV. Talc acts in a different way. It reacts as a chemical reagent with the molten chains of PHB/PHBV, while the reaction product acts as the true nucleating agent, which lowers the crystallization barriers of PHB and PHBV. ¹H NMR spectroscopy provides evidence for the reaction between PHB and talc and supports the proposed nucleation mechanism. Copyright © 2005 Society of Chemical Industry     

国外塑料用无机填料新产品及其应用

介绍了近年国外塑料用传统无机填料和母料新产品性能、特点及其应用,包括超细滑石、亚微米级滑石、碳酸钙母料、中空玻璃微球、片状玻纤粉等新型填料。填料微型化、超细化是无机填料技术发展方向。     

Synthetic talc advances: Coming closer to nature,added value,and industrial requirements

Over the past 2 years, the synthetic process of talc particles has evolved considerably, leading to an inexpensive, convenient, and rapid process that is compatible with industrial requirements. In addition to facilitate the synthetic talc preparation, the evolution of the synthesis process has led to an improved crystallographic arrangement of the talc particles in both the c* direction and (ab) plane. In the present study, the most recent process was investigated with respect to the reaction time, temperature, pressure, pH, and salt concentration to determine the optimal reaction parameters. In the geomaterial industry, X-ray diffraction is routinely used for powder material characterization; the crystallinity of our synthetic talc was evaluated by this technique through measurements of the Coherent Scattering Domain (CSD) size. A crystalline lamellarity index was defined as the ratio between the CSD size values in the (ab) plane and c^⁎ direction. These crystallinity characteristics were used to define the quality of the synthetic talc and its suitability for potential industrial markets.     

大豆脂肪氧合酶(LOX)的固定化及增强稳定性

以活性白土、滑石粉为载体采用吸附法固定化大豆脂肪氧合酶(LOX)的优化条件为:(1)酶液对活性白土的用量比为897U/mg,在浓度为0 05mol/L、pH=7 0的磷酸盐缓冲液中20℃搅拌吸附30min;(2)酶液对滑石粉的用量比为238U/mg,在浓度为0 05mol/L、pH=8 0的磷酸盐缓冲液中10℃搅拌吸附15min。经放大后实验重复性良好。上述固定化酶置于0～4℃保存20d,酶活损失分别为19 2%和17 7%;与游离酶相比,能加快酶促反应的速度并使产率分别提高9 6%和42 5%。以海藻酸钠为载体采用包埋法得到的固定化酶珠的耐热、耐酸碱、耐有机溶剂能力较游离酶有很大提高,在φ(甘油)=75%的水溶液中保存33d,酶活基本保持不变;在50℃热处理60min后酶活仍能保持90%。     

合成纤蛇纹石润滑油添加剂的研究

分别利用三种实验方法进行了蛇纹石的水热合成.制备的粉体分别用X射线衍射仪(XRD)、透射电子显微镜(TEM)进行成分与形貌的表征分析.结果表明以滑石与氧化镁为反应物的方法在220℃、pH=13、反应30 h条件下成功合成出纤蛇纹石纳米管,并讨论了水热合成条件对产物的影响.含有纤蛇纹石的合成产物及天然蛇纹石分别经表面修饰剂修饰后进行四球摩擦磨损实验来研究其摩擦性质,人工合成蛇纹石表现出比天然蛇纹石更好地减摩抗磨效果.     

Mixed percolating network and mechanical properties of polypropylene/talc composites

Injected polypropylene/talc composites were studied to evaluate the conditions leading to the formation of a mixed talc/polymer crystalline lamella percolating network and the influence of such a network on the nanocomposite mechanical properties. The talc was either conventional micrometer‐sized (conventional talc) or submicrometer‐sized particles (μ‐talc). In the case of μ‐talc, several talc fractions were studied, ranging from 3 to 30 wt %. The nanocomposite crystallinity was characterized with differential scanning calorimetry and wide‐angle X‐ray scattering. Talc was found to act as a nucleating agent, and only the α phase was detected. Through quantification on a Wilchinsky diagram, the talc particles were found to lie in the sample plane, the polypropylene crystalline lamellae being orthotropically distributed perpendicularly to the talc particles. The mechanical properties of the composites were tested in different directions by tensile and compression tests. The mechanical behavior of the composites confirmed the microstructural model. For low talc loadings, the composite moduli could not be well fitted by a law of mixtures. The large difference between the observed and predicted moduli was attributed to the formation of a mixed percolating network, including talc particles and polypropylene crystalline lamellae. At high talc loadings, when the mixed percolating network was completely formed, the reinforcement could well be described by parallel coupling, which indicated a classical reinforcement mechanism. Finally, the value of the critical talc fraction, at which the mixed percolating network was formed, was examined as a function of talc. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Preparation of porous material from talc by mechanochemical treatment and subsequent leaching

Synthesis of porous silica via mechanochemical treatment of talc and subsequent acid leaching was investigated by X-ray diffraction (XRD), Fourier transformation infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and N₂ adsorption techniques. Raw talc was ground for different times and then leached with 4 M hydrochloric acid (HCl) at 80 °C. Grinding for 6 h and subsequent leaching for 2 h of raw talc produced the porous silica with a specific surface area of 133 m²/g and total pore volume of 0.22 ml/g. The increase in specific surface area (S_BET) of the porous silica reflected the formation of micropores of 1.21.8 nm and mesopores of 4.05.5 nm in diameter inside the porous structure. The number of micropores decreased with prolonged leaching time, which can be attributed to a condensation reaction. The characteristic of hysteresis loop indicated mainly slit-shaped pores. The apparent activation energy for the leaching process was calculated to be about 21.6 kJ/mol, indicating that the kinetic process of talc leaching was the diffusion-controlled reaction. Mechanochemical treatment may promote the amorphization of talc, being greatly favorable to the subsequent leaching.     

Assessment of weld line performance of PP/Talc moldings produced in hot runner injection molds

Weld lines are weak regions in thermoplastic injection moldings caused by low molecular entanglement and unfavorable orientation. Their occurrence may lead to a significantly reduced mechanical performance of the products. Therefore, when weld lines are likely to occur in molded products, they must be taken into account during the mechanical and technological design processes. The weld lines become more critical when particulate fillers are compounded with the polymer. The performance of weld lines in talc‐filled polypropylene box moldings produced with a double‐gated hot runner mold is assessed in this work. The processing conditions were varied in order to cause morphology and tensile‐impact resistance changes. The weld performance at room temperature was assessed in terms of the energy absorbed in the impact tests. It was found that the performance depends on the injection temperature, the injection rate, and the orientation of the talc particles in the weld‐line plane. J. VINYL ADDIT. TECHNOL., 13:159–165, 2007. © 2007 Society of Plastics Engineers     

The effects of epoxy resin nano particles on shrinkage behavior and thermal stability of talc-filled polypropylene

Reactive mixing of epoxy resin with polypropylene (PP) and talc were carried out on a co-rotating twin screw extruder. The prepared samples were injection molded to produce the specimens for the measurements of the shrinkage rate. The microstructure of the composites was studied by scanning electron microscope and correlated to the orientation of filler particles and shrinkage behavior. The nano size epoxy resin particles are obvious in SEM images both in the PP matrix and also adhered on the talc powders. The shrinkage measurement revealed that, using epoxy resin in the formulations, leads to a reduction of 14.3% in the shrinkage rates which is isotropic in both flow and transverse directions. The oven aging test at 100 °C showed a significant effect of epoxy resin on increasing the thermal stability of composites. The stabilization effect of epoxy resin was more pronounced at higher epoxy resin content. It is believed that the metallic impurities on the surface of talc powder deactivated by the functional groups of epoxy resin and the degradation reaction rate decreased.     

Influence of talc genesis and particle surface on the crystallization kinetics of polypropylene/talc composites

Talc is a laminar silicate, considered as an excellent nucleating agent for polypropylene (PP) crystallization. However, properties of PP/talc composites depend on the morphology, size, and surface of mineral particles. In this sense, talc from several ores, having different morphology, imparts specific characteristics on these materials. Also, taking into account that PP‐talc adhesion is not necessarily good due to the apolar character of PP, talc surface has been modified in order to increase this parameter. In this work, the effects of talc genesis, geomorphologic aspects, and particle surface characteristics on crystallization of PP/talc composites are analyzed. Isothermal crystallization of PP/talc composites was studied by using differential scanning calorimetry, based on Avrami model. The final crystalline morphology of talc‐filled PP was analyzed by means optical microscopy. The results show that the blocky talc morphology favors even more the crystallization compared to the platy one, at the same particle size. Taking into account the surface treatment studied in this work, the talc surface is made hydrophobic and the particle delamination is favored. As a consequence, so‐modified talc is very effective in increasing the crystallization temperature of PP and the nuclei number that grow during the crystallization with respect to the untreated talc. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Effect of talc surface treatment on the mechanical properties of composites based on PP/LDPE blend matrices

A study has been made of property optimization of a composite based on low density polyethylene and polypropylene (PP) blend matrices with talc modified by a titanate coupling agent. Analysis shows that the flexural properties improve with increasing content of both talc and polypropylene. However, the tensile moduli show a different behavior. Tensile strength is hardly affected by the filler content at PP percentages in the matrix above 50 percent. The surface modified talc gives rise to higher mechanical properties than the unmodified talc. This improvement is more noticeable as talc and PP percentages in the composite is increased. Scanning electron microscopy has shown the effect of the coupling agent at the filler/polymer matrix interphase and the greater affinity between talc and polypropylene.     

Structure and properties of talc-filled polyethylene and nylon 6 films

Water vapor transmission rates can be reduced by as much as 50% in polyethylene by using talc as a filler. The oxygen permeability as well as water vapor transmission rates are similarly reduced by talc in nylon 6 films. The films show low elongation at break and reduced breaking strenth in the presence of talc. The yield strength and the modulus increase with the amount of talc, whereas the elongation at yield decreases. The mechanical and the barrier properties change with the size of the filler, the smaller size being more favorable. Talc probably acts as a nucleating agent and increases the crystallinity in polyethylene and nylon. Polyethylene unit cells in talc-filled films are oriented with the (110) planes parallel to the (001) planes of talc. Nylon 6 crystals, which are in the α form in the presence of talc, are oriented with the hydrogen bonded sheets, the (002) planes, parallel to the (001) planes of talc. In both polyethylene and nylon 6, talc is oriented with the c-axis normal to the plane of the film, i.e., with the broad faces of talc flakes in the plane of the film. Lattice matching between the polymer and talc suggests epitaxy to be a contributing factor for the observed orientation of polyethylene and nylon 6 crystals.     

Crystallization behavior of polypropylene filled with surface-modified talc

Talc-filled polypropylene (PP) composites were prepared by extrusion in a wide composition range (0–40 wt %). To improve the affinity relation between talc and the PP matrix, we modified the talc surface with silane coupling agents. Differential scanning calorimetry investigations on test samples, prepared by injection moulding, revealed that the talc content and its surface modification had a pronounced effect on the crystallization behavior of the filled PP composites. The experimental results indicate that a talc concentration of 2 wt % strongly affects the nonisothermal crystallization process of the PP, especially when talc is silane treated Isothermal crystallization experiments on samples with minimum amounts of talc (2 wt %) revealed an improved nucleation activity with silane-treated talc. © 1996 John Wiley & Sons, Inc.