Mineralogical and chemical properties of FGD gypsum from Florina,Greece

BACKGROUND: The aim of this work is to define the chemical and mineralogical composition of the fuel gas desulphurization (FGD) gypsum produced from the Meliti thermal power plant in the region of Florina in North West Greece, in order to investigate potential uses in the cement industry. Mineralogical and microprobe analyses were carried out on FGD gypsum samples collected from the Meliti 330 MW lignite‐fired power plant. RESULTS: Results show that the main component of the FGD gypsum is pure mineral gypsum (CaSO₄·2H₂O). The particle size of the gypsum ranges from 5 to 50 µm and the crystals are mainly of rhomboid shape. Microprobe analysis shows that the concentration of CaO and SO₃, which are the main components, range from 31.9%–32.5% and from 45.90–46.40%, respectively. CONCLUSION: This FGD gypsum can easily substitute the natural gypsum used in the production of cement. Copyright © 2007 Society of Chemical Industry     

Comparison of the physicochemical properties and mineralogy of Chinese (Beihai) and Brazilian kaolin

Beihai area (China) has about 500 million tons kaolin reserves with potential applications in ceramics, paint, plastic and rubber-filler industries, but unlike the Brazilian kaolin, it is not good in paper-coating industry. In order to understand the differences between Chinese (Beihai) and Brazilian kaolin, their individual physicochemical properties, morphologies, crystal structures, and surface characteristics were systematically investigated and compared. The results showed that the viscosity concentration, specific surface area and zeta potential of Brazilian kaolin were higher than those of Beihai kaolin. SEM and TEM images revealed that Brazilian kaolin had more regular particle shape, smoother surface and larger diameter–thickness ratio than those of Beihai kaolin. Moreover, XRD and TG/DSC analyses exhibited that Beihai kaolin was low ordered kaolinite with lower value of Hinckley index, average flake thickness along c-axis and endothermic peak temperature as compared to Brazilian kaolin. Furthermore, the crystal structures refined by the Rietveld method of Beihai kaolin showed a greater distortion of [SiO₄] tetrahedron than that of Brazilian kaolin. It can be concluded that low viscosity concentration, low degree of order, and irregular particle shape of Chinese (Beihai) kaolin are the reasons why it is not suitable for use in the paper-coating industry.     

The influence of kaolin and calcined kaolin on SBR composite properties

Kaolin is a naturally abundant and cheap ore, which can impart various properties to rubber composites besides lowering its cost. In this work, kaolin and thermally treated kaolin (especially m‐kaolinite), which is the most active species of kaolin were added to styrene–butadiene rubber composites in different concentrations ranging between 10 and 50 phr to study their effect on SBR rheometric, physical, mechanical, and thermal properties. The main aim of this study was to state whether the activity of calcined kaolin will allow it to work as a bifunctional additive (i.e., reinforcing filler and accelerator) or an adverse one (i.e., working as an active radical breaking the polymer chains). The study revealed that SBR containing calcined kaolin performed better properties than those containing kaolin indicating that calcined kaolin worked as a bifunctional additive in SBR composites. POLYM. COMPOS., 35:570–580, 2014. © 2013 Society of Plastics Engineers     

Thermal analysis of compounded poly(vinyl chloride)

Differential thermal analysis of mixtures of poly(vinyl chloride) and dioctyl phthalate shows a compound endothermic peak due to decomposition of both polymer and plasticizer. The thermal behavior of other plasticizers is similarly affected in the presence of poly(vinyl chloride). The addition of zinc oxide or ferric oxide decreases the thermal stability of the mixture and, under isothermal conditions, a resultant induction period allows the estimation of an activation energy for the dehydrochlorination of poly-(vinyl chloride) and of the relative effectiveness of thermal stabilizer systems.     

An X-ray,EPMA, and oxygen isotope study of vermiculitized micas in the ultramafic rocks at Askos,Macedonia, Greece

Extensive metasomatic zones of vermiculite-, tremolite-, chlorite-, and talc-rich rocks have been developed at the contacts of serpentinized ultramafic bodies and surrounding two-mica gneisses in the Askos area, Macedonia, Greece. These zones are probably related to the intrusion of acid magmatic bodies in the area. X-ray and EPMA studies confirmed the formation of vermiculite through a layer-by-layer transformation of original micas. In decreasing abundance, the following mixed-layer and discrete phases were identified: biotite/trioctahedral vermiculite (hydrobiotite), biotite/smectite, trioctahedral chlorite/trioctahedral vermiculite (corrensite), vermiculite/smectite and discrete biotite, vermiculite, chlorite and talc. The 2–20 μm fraction of the vermiculitic samples consists mostly of biotite/vermiculite (>40%) with the biotite percentage dominating in the mixed phase. Lower abundances (20–40%) of biotite/smectite and chlorite/vermiculite occur in both finer fractions (2–20 and <2 μm) of all vermiculitic samples. Vermiculite/smectite is very abundant in the <2 μm fractions of most vermiculitic samples. The DTA curves of the samples analyzed are characteristic of Mg-vermiculites. The electron microprobe analyses show a gradual K leaching from precursor mica with increasing degree of weathering. Oxygen isotope results confirm this assumption. Initially, hydrothermal fluids derived from the neighboring granitic intrusions, were responsible for the micatization of the primary minerals of the ultramafic bodies. Hydrothermal activity was also responsible for the partial formation of corrensite. Consequently, water moving downwards was very important for the formation of the vermiculite and other clay mineral mixed-layer phases through the alteration of micas and chlorite. The low relief and the long-lasting tectonic stability of the area were essential for the development of a significant thickness of the vermiculite zones. These vermiculites have properties desirable in certain building, agriculture, and horticulture products.     

Morphology and thermal properties of poly(ethylene terephthalate)‐modified kaolin nanocomposites

Kaolin particles were dispersed in a PET (poly(ethylene terephthalate)) matrix using a displacement procedure in which kaolin was initially treated with potassium acetate and, subsequently, melt‐blended with PEO and PET. The disappearance of characteristic peaks in XRD patterns of chemically treated particles revealed that the crystalline form and layered structure of kaolin particles were mainly destroyed. Scanning electron microscopy and transmission electron microscopy showed that the thickness of dispersed particles were generally in the range of 10–100 nm. It was also observed that the dispersion level of the chemically treated kaolin was much better than that of “as received” kaolin particles. Rheological studies showed the formation of a network‐like structure in samples containing the chemically treated kaolin as a result of improved dispersion of particles. It was also observed that both the kaolin particles and modifiers could accelerate the degradation process and lower the molecular weight of the PET. The introduction of kaolin particles shifted the crystallization temperatures of PET to higher temperatures. It was observed that the incorporation of a chain extender significantly restricted the crystallization process. The Avrami–Jeziorny analysis confirmed the alteration of the crystalline structure of the filled polymer. Based on TGA thermograms the decomposition temperature of PET–kaolin composites was slightly lower than that of the neat PET. POLYM. COMPOS., 37:1443–1452, 2016. © 2014 Society of Plastics Engineers     

复合橡胶改性聚苯乙烯的结构与性能

研究了复合橡胶对高抗冲聚苯乙烯(HIPS)结构与性能的影响,并用透射电子显微镜对HIPS进行了表征。结果表明:低顺聚丁二烯橡胶(简称低顺橡胶)能增加HIPS橡胶相体积分数,使橡胶粒子形态分布更均匀;高顺聚丁二烯橡胶(简称高顺橡胶)有利于提高产品的韧性;低顺橡胶对HIPS弯曲强度和拉伸强度的增加贡献更大;采用高顺橡胶与低顺橡胶复合,能够协调HIPS的韧性、弯曲强度和拉伸强度。     

Tensile properties of polypropylene/kaolin composites

Tensile properties of isotactic polypropylene filled with particulate kaolin fillers were evaluated in the composition range 0–60 wt % kaolin. Tensile modulus increased with filler concentration while breaking elongation and tensile strength decreased. The modulus increase was attributed to the restriction on the molecular mobility of the polymer imposed by kaolin particles. The decrease in elongation was also an effect of this restriction coupled with interference to stress transfer by the filler particles. Generation of discontinuity in the composite structure through formation of stress concentration points accounted for the tensile strength decrease. Morphology studies by SEM also indicated the introduction of stress concentration points by the presence of bare and nonadherent kaolin particles and their agglomerates with sharp edges in these composites.     

高岭土的改性及其从含砷水中除砷性能研究

以高岭土为原料通过碱熔合成得到类似于分子筛的笼状骨架结构,并将Fe3+通过离子交换吸附,负载在其骨架上,实现改性;利用改性后的吸附剂具有大的活性表面积,以及砷阴离子(AsO43-)与Fe3+的强配位能力,实现了基于配体交换的固液分离的从微量含砷水中去除砷。实验表明,改性高岭土除砷材料具有良好的吸附除砷性能,在含As(V)5~40 mg/L的水中,在实验条件下平衡除砷率可达99%以上。经测定,该材料对As(V)的吸附量可达3.7 mg/g除砷剂以上,并具有水中常见共存离子不影响砷的去除效果,以及不对水体产生二次污染等特点。处理后的水的砷含量可达到国家饮用水标准甚至更低。获得一种新的从饮用水源中去除砷的方法。     

Major- and trace-element mobility in altered volcanic rocks near Stypsi,Lesbos, Greece and genesis of a kaolin deposit

Major- and trace-element mobilities have been investigated in hydrothermally altered zones of Miocene volcanic rocks on the island Lesbos. Three types of alteration have been recognized, and are characterized by the mineralogical composition: (a) zone of illite and smectite; (a-b) transitional zone of kaolinite, illite, smectite; and (b) zone of kaolinite.The alteration zones are encountered in the Lower Lava Unit (latite—andesite) and are related to a channel (fault) which allowed the circulation of hydrothermal fluids. The zonation of hydrothermal alteration is attributed to the step-wise character of the kaolinitization process.The following relationships between mineral paragenesis of the different alteration zones and element behaviour are apparent.

• 1.(1) K and Rb enrichment relative to fresh volcanic rock occurs in zones a and a-b, while K and Rb are leached during destruction of illite in the kaolinite zone (b).
• 2.(2) Zones a and a-b are characterized by depletion of Fe, Mg, Ca, Na, P, Sr, Zn, Cu, Ni and Ba when compared with the unaltered volcanic rock.
• 3.(3) Relative to the volcanic rock, the kaolinitic zone (b) is characterized by depletion of Fe, Mg, Ca, Na, K, P, and Ti and enrichment of Al. Of the trace elements Nb, Zr, Ce, Nd and La are enriched while Sr, Rb, Zn, Cu, Ni, Cr, V, Ba and Sc are depleted.
• 4.(4) There is no evidence of Cu, Ni, Cr, Zn or Mo addition to the system by the hydrothermal fluids. Recognition of the hydrothermal origin of Stypsi Kaolin is based on the following criteria: (a) mineralogical zonation; (b) association of pyrite with hydrothermally altered zones; (c) Hg-geochemical anomalies of the alteration zones, which are indicative of postvolcanic geothermal activity; (d) comparison of the analytical data derived from the present study with relevant data on kaolins of known hydrothermal origin.

     

煅烧高岭土对EPDM性能的影响

研究煅烧高岭土对EPDM性能的影响。结果表明，煅烧高岭土对EPDM胶料的硫化有延迟作用。但并不显著；煅烧商岭土对EPDM有一定的补强作用，随着煅烧高岭土用量的增大，EPDM硫化胶邵尔A型硬度、定伸应力、拉断伸长率和拉断永久变形增大．拉伸强度和撕裂强度先增大后减小；适量的煅烧高岭土可改善EPDM硫化胶的耐溶剂性能。     

Dielectric properties and structures of melt‐compounded poly(ethylene oxide)–montmorillonite nanocomposites

The dielectric dispersion and relaxation process in melt‐compounded hot‐pressed poly(ethylene oxide) (PEO)–montmorillonite (MMT) clay nanocomposite films of 0–20 wt % MMT concentration were investigated over the frequency range 20 Hz to 1 MHz at ambient temperature. X‐ray diffraction study of the nanocomposites evidences that the PEO has been intercalated into the MMT interlayer galleries with a helical‐type multilayer structures, which results the formation of unique parallel plane PEO–MMT layered structures. The relaxation times corresponding to PEO chain segmental motion were determined from the loss peak frequencies of different dielectric formalisms and the same is used to explore the interactions compatibility between PEO molecules and the MMT nano platelets. It is revealed that the loading of only 1 wt % MMT in PEO matrix significantly increases the PEO chain segmental motion due to intercalation, which further varies anomalously with increase of MMT concentration. The real part of dielectric function at 1 MHz, relaxation time, and dc conductivity of these melt‐compounded nanocomposites were compared with the aqueous solution‐cast PEO–MMT films. Considering the comparative changes in the values of various dielectric parameters, the effect of synthesization route on the intercalated/exfoliated‐MMT structures and the PEO chain dynamics were discussed. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Novel‐modified kaolin for enhancing the mechanical and thermal properties of poly(vinyl chloride)

Novel surface‐modified kaolin with liquid‐like behavior was prepared. The characteristics of the solvent‐free kaolin fluid were evaluated by using Fourier transform infrared spectroscopy, WAXD, thermogravimetric analysis, and transmission electron microscopy. The polyvinyl chloride (PVC)/solvent‐free kaolin fluid composites were also fabricated via melt mixing. Owing to the novel surface modification, the hydrophilic kaolin surface grafted long organic chains, which made that the solvent‐free kaolin fluid could be well dispersed in PVC matrix and firmly integrated with the PVC matrix. The resulted composites exhibited better heat resistance and mechanical properties than neat PVC resins. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers     

P(AA-co-AMPS)/Kaolin复合高吸水树脂的制备及结构性能研究

以丙烯酸(AA)、2-丙烯酰胺基-2-甲基丙磺酸(AMPS)和高岭土(Kaolin)为原料,采用溶液聚合法分别制备出聚丙烯酸(PAA)高吸水树脂、聚(丙烯酸-co-2-丙烯酰胺基-2-甲基丙磺酸)(P(AA-co-AMPS))高吸水树脂、P(AA-co-AMPS)/Kaolin复合高吸水树脂,并通过傅里叶变换红外光谱、扫描电镜、X射线衍射等测试方法对其结构与性能进行表征。结果表明:Kaolin与P(AA-co-AMPS)高吸水树脂之间为物理共混;PAA高吸水树脂、P(AA-co-AMPS)高吸水树脂和P(AA-co-AMPS)/Kaolin复合高吸水树脂的吸水倍率分别为231,323,357 g/g,吸盐水倍率分别为35.6,64.1,66.4 g/g,保水率分别为51.3%,55.6%,57.9%,凝胶形变量分别为3.75,4.10,2.23 mm;树脂的吸水速率由小到大依次为PAA高吸水树脂、P(AA-co-AMPS)高吸水树脂、P(AA-co-AMPS)/Kaolin复合高吸水树脂。     

甜菜碱改性高岭土/NR复合材料的性能研究

通过甜菜碱改性高岭土悬浮液与天然胶乳混合以凝聚共沉法制备甜菜碱改性高岭土／NR复合材料，研究甜菜碱溶液质量分数、高岭土用量、碱金属离子种类等对复合材料物理性能的影响。结果表明，甜菜碱改性高岭土对硫化胶具有明显的补强作用。扫描电镜分析表明硫化胶拉伸断面出现丝网形貌，透射电镜分析表明甜菜碱改性高岭土粒子与NR基体结合紧密，界面比较模糊。