Academic literature on the topic 'Fiber-shape calcium carbonate'

Calcium sulphate is rich in natural resources and by-product of many industrial processes. However, most calcium sulphate product was only used with low added value or treated as waste, harmful to environment. If the calcium sulphate can be used as papermaking filler, very high added value can be gained and also the environment problem can be solved. In this paper calcium sulphate from by product of industry was characterized by X-ray diffractometer (XRD) and scanning electron micrograph (SEM), and then used as papermaking filler. The influence of calcium sulphate filler on pulp suspension and paper properties was studies. The results showed that the calcium sulphate fillers were composed of three crystal forms, dihydrate, hemihydrate, anhydrite, and it was needle or fiber shape, hollow in the middle; calcium sulphate showed high brightness and high conductivity in water, compared with talc or ground calcium carbonate(GCC) filler. When calcium sulphate filler was used in papermaking process the filler retention was very small because of its high solubility in water. Calcination at high temperature can lower the solubility of calcium sulphate and slightly increase the retention, but the retention was still quite small. The future work should focus on controlling the solubility of calcium sulphate.

Microscopic analysis of fossils from the Lightning Ridge district of northwestern New South Wales, Australia, shows that opal has been typically deposited in variable cavities left by the degradation of the original organic material. Fine-grained, clay-rich sediments have preserved the external morphology, and opalization has produced detailed casts with different modes of preservation of internal details. Plant remains include cones, cone scales, fruiting bodies, and seeds, but the most common specimens are twigs, stems, and wood fragments. These specimens commonly contain angular inclusions that represent small tissue fragments produced by the degradation of the original wood. Inclusions commonly have a “hollow box” structure where the organic material has decomposed after the initial opal filling of the mold. These spaces commonly contain traces of the cellular architecture, in the form of wood fiber textures imprinted on the cavity wall, degraded cellular material, and silicified tracheids. Opal casts of mollusk shells and crustacean bioliths preserve the shape but no calcium carbonate residue. Likewise, opal casts of vertebrate remains (bones, teeth, osteoderms) lack preservation of the original bioapatite. These compositions are evidence that burial in fine clays and silts, isolated from the effects of water and oxygen, caused protracted delays between the timing of burial, decomposition, and the development of vacuities in the claystones that became sites for opal precipitation. The length of time required for the dissolution of cellulosic/ligninitic plant remains, calcium carbonate items, and calcium phosphates in bones and teeth cannot be quantified, but evidence from opal-bearing formations worldwide reveals that these processes can be very slow. The timing of opalization can be inferred from previous studies that concluded that Cenozoic tectonism produced faults and fissures that allowed horizontal and lateral movement of silica-bearing groundwater. Comparisons of Australian opal-AG with opal from international localities suggest that opalization was a Neogene phenomenon. The transformation of Opal-AG → Opal-CT is well-documented for the diagenesis of siliceous biogenic sediments and siliceous sinter from geothermal areas. Likewise, precious and common opal from the late Miocene Virgin Valley Formation in northern Nevada, USA, shows the rapidity of the Opal-AG → Opal-CT transformation. Taken together, we consider this evidence to indicate a Neogene age for Lightning Ridge opalization and by inference for the opalization of the extensive opal deposits of the Great Artesian Basin in Australia. New paleontology discoveries include a surprising level of cellular detail in plant fossils, the preservation of individual tracheids as opal casts, evidence of opalized plant pith or vascular tissue (non-gymnosperm), and the first report of Early Cretaceous coprolites from New South Wales, Australia.

The leading objective of this experimental study is to perform a Short-term Creep Testing on samples (coupon test) obtained from a private company in order to learn the durability of the Unsaturated Polyester Resin (UPR) material with and without Calcium Carbonate (CaCO3) on the applied cross-arm application according to ASTM E139. Through the method of flexural test jig (three point bending test) along with the usage of the furnace chamber HK160, samples then examined with initial temperature of 30°C until it breaks down. Result has been evaluated using conventional method for predicting the life-long purpose of the samples for future reference and analysis. The configurations or the patterns of the failure through (conventional) method recorded for short term test inside HK160 Chamber furnace fails at temperature of 120°C for samples without CaCO3 the samples fails and crack. Therefore, the samples with due to the material of UPE with FRP in a bar shape are said to have Ultimate Temperature for Failure of 120°C. Further details are crucial for advance analysis in the future research purposes.

This study deal with the development and investigation of a novel hybrid nano-shell plant fiber biocomposite. Nano-calcium carbonate CaCO3 ranging from 1 to 5 wt% and 20 wt% banana fiber-filled hybrid biocomposite were prepared using a hand lay-up process followed by applying load on a closed mold. Nano-CaCO3 of near-uniform size and shape was synthesized from Achatina Fulica through a mechanochemical technique. The effect loading fiber of uniform 30 mm size on the mechanical, physical, thermal properties of greenpoxy composite was investigated. The influence of nano-CaCO3 loading (1 to 5 wt%) on banana fiber-filled greenpoxy composite, dynamic mechanical properties, tensile, flexural, impact strength was further investigated. The result showed that the loading of banana fiber improved mechanical properties and negatively affected temperature dependence storage modulus, loss modulus, and tan δ. Better load carrying and stress distribution capacity of the fiber within the biocomposites can be attributed to the high strength and stiffness observed for these series. The poor thermal properties of banana fiber can be ascribed to a decrease in the temperature dependence properties. The loading of nano-CaCO3 improved most of the banana-filled greenpoxy biocomposite, and hybrid composite with 2 wt% nano-CaCO3 offered superior properties. Uniform dispersion, excellent matrix/nano-CaCO3/banana fiber adhesion provided a strong structure, resulting in improved mechanical and temperature-dependant properties.

Abstract This study presents a laboratory experimental research to determine the characteristics of lost circulation materials (LCMs) capable of addressing thermal degradation, providing bridging and sealing in geothermal conditions. Eleven different materials were tested: Walnut Fine, Walnut Medium, Sawdust, Altavert, Graphite Blend, Bentonite Chips, Micronized Cellulose (MICRO-C), Magma Fiber Fine, diatomaceous earth/amorphous silica powder (DEASP), Cotton Seed Hulls, and a Calcium Carbonate Blend. The filtration and sealing pressure of the LCMs were measured with HPHT equipment up to 149 °C (300 °F). Besides, the particle size distribution (PSD) of fine granular materials was measured. The results show that the performance of some LCM materials commonly used in geothermal operations is affected by high temperature. Characteristics such as shape and size made some materials more prone to thermal degradation. Also, it was found that the PSD of LCMs is a key factor in the effectiveness of bridging and sealing fractures. The results suggest that granular materials with a wide particle size distribution PSD are suitable for geothermal applications.

Cette recherche vise à synthétiser différents types et formes de particules de carbonate de calcium (CaCO3) à l'échelle submicrométrique et nanométrique, et à étudier leurs applications en tant que charges renforçantes pour les composites de caoutchouc naturel (NR). L'étude a donc été divisée en deux parties. Premièrement, la procédure de préparation des particules de CaCO3 était basée sur la méthode de précipitation en solution entre les ions carbonate (CO32-) et les ions calcium (Ca2+). La deuxième partie concerne l'étude des propriétés mécaniques des composites NR/CaCO3. La première partie a commencé par la précipitation de (NH4)2CO3 et de CaCl2 dissous dans 50 % en poids de saccharose comme milieu aqueux. Cette condition a entraîné la formation de CaCO3 sphérique, ce qui a été mis en évidence au microscope électronique à balayage (MEB). L'analyse au microscope électronique à transmission (TEM) a révélé une taille de particule de 0,42 ± 0,14 µm avec un rapport d'aspect d'environ un. Lorsque la réaction de précipitation s'est produite en présence d’huile d'olive saponifiée, la propriété de surface du CaCO3 est passée d'hydrophile (angle de contact avec l'eau de 28 ± 2°) à superhydrophobe (angle de contact avec l'eau de 163 ± 2°). Les phases polymorphes typiques de CaCO3 ont été caractérisées par diffraction des rayons X (DRX), infrarouge à transformée de Fourier par réflexion totale atténuée (ATR-FTIR) et spectroscopie Raman. Ces techniques ont révélé que le CaCO3 sphérique non traité et traité représentait environ 99 % du polymorphe de la vatérite. Dans le processus de précipitation utilisant des solutions aqueuses 1 M de Na2CO3 et 1 M de CaCl2 réalisé à 80 ± 1 °C, du CaCO3 sous forme de fibres agglomérées a été obtenu avec un rapport d'aspect compris entre 8 et 9. Le CaCO3 superhydrophobe sous cette forme a également été synthétisé avec succès. L'angle de contact avec l'eau des fibres traitées et non traitées est respectivement de 29 ± 2° et 167 ± 2°. De plus, le CaCO3 sphérique dispersé dans l'eau à 80°C a donné naissance à des nanoparticules de CaCO3 en forme de fibre qui ont été obtenues via la transformation de la vatérite sphérique en aragonite nanofilaire longue avec le rapport d'aspect le plus élevé de 156,9 par rapport aux autres formes de CaCO3. La fibre CaCO3 non traitée était hydrophile avec un angle de contact avec l'eau de 31 ± 1°, tandis que la fibre CaCO3 traitée avec du savon donnait un angle de contact avec l'eau de 165 ± 5° ; elle était donc superhydrophobe similaire aux autres polymorphes de CaCO3 synthétisés. La DRX a révélé que le CaCO3 en forme de fibres, non traitées et traitées, contenait en majorité de l'aragonite et en moindre mesure de la vatérite et de la calcite. La stabilité thermique de différents types de CaCO3 a également été évaluée par analyse thermogravimétrique (TGA). Les résultats ont montré la calcination des cristaux de CaCO3, du saccharose et du savon. La deuxième partie a consisté à incorporer le CaCO3 préparé (0, 5, 10, 20, 40, à 60 pce) dans du latex naturel (NR). Il a été constaté que la vatérite CaCO3 non traitée et traitée était stable dans le milieu latex NR. De plus, les polymorphes du CaCO3 non traité et traité en forme de fibres étaient également stables dans leurs formes lorsqu'ils étaient ajoutés au latex NR. Les propriétés mécaniques du NR/CaCO3 comprenaient la résistance à la traction, l'allongement à la rupture, la résistance à la déchirure et la dureté Shore A. Il a été constaté que la résistance à la traction des composites NR/CaCO3 augmentait lorsque la charge de CaCO3 augmentait. La résistance à la traction du NR s'est améliorée de 22,68 ± 2,22 MPa de NR pur jusqu'à 23,94 ± 0,97 MPa lorsque des poudres de CaCO3 sphériques non traitées (20 phr) ont été ajoutées, et à 25,28 ± 0,80 MPa de CaCO3 sphérique traité (20 phr) de NR rempli. (...)
This research aims to synthesize different types and shapes of calcium carbonate (CaCO3) particles at a submicrometric and nanoscale, and investigate their applications as reinforcing fillers for natural rubber (NR) composites. The study was therefore divided into two parts. Firstly, the preparation procedure of CaCO3 particles was based on the solution precipitation method between carbonate ions and calcium ions. The second part focused on investigating the mechanical properties of NR/CaCO3 composites. The first part started with the precipitation of (NH4)2CO3 and CaCl2 dissolved in 50% by weight of sucrose as the aqueous medium. This condition resulted in spherical CaCO3 with particle size of 0.42±0.14 µm with an aspect ratio of about one. When the precipitation reaction occurred in the presence of olive soap, the surface property of the CaCO3 was changed from hydrophilic (water contact angle of 28±2o) to superhydrophobic powders (water contact angle of 163±2o). The typical polymorphic phases of CaCO3 were characterized. The results revealed that both untreated and treated spherical CaCO3 were about 99% of the vaterite polymorph. In the precipitation process using Na2CO3 and CaCl2 aqueous solutions performed at 80±1C, bundle-liked CaCO3 was obtained with an aspect ratio in the range of 8–9. The superhydrophobic bundle-liked CaCO3 was also successfully synthesized by soap treatment. The water contact angle of untreated and treated bundle-liked are 29±2o, and 167±2o, respectively. Furthermore, the spherical CaCO3 dispersed in water at 80C resulted in the fiber-shaped CaCO3 nanoparticles which were achieved via the polymorph transformation from spherical vaterite to long nano-wired aragonite with the highest aspect ratio of 156.9. The untreated fiber CaCO3 was hydrophilic with a water contact angle of 31±1o, while the treated fiber CaCO3 with soap resulted in 165±5o of water contact angle, hence it was superhydrophobic similar to other synthesized CaCO3 polymorphs. The XRD revealed that the untreated and treated bundle-liked and fiber-shaped CaCO3 contained the majority of aragonite followed by vaterite and calcite polymorphs. The second part was carried out to incorporate the prepared CaCO3 (0,5,10,20,40,60 phr) in NR latex. It was found that the CaCO3 polymorphs were stable in the NR latex medium. The mechanical properties of NR/CaCO3 included tensile strength, elongation at break, tear strength, and hardness Shore A. It was found that the tensile strength of NR/CaCO3 composites increased when CaCO3 loading was increased. The tensile strength of NR improved from 22.68±2.22 MPa of neat NR up to 23.94±0.97 MPa when untreated spherical CaCO3 powders (20 phr) were added, and to 25.28±0.80 MPa of treated spherical CaCO3 (20 phr) filled NR. The maximum tensile strength of NR/untreated bundle-liked CaCO3 was 30.59±3.50 MPa at 40 phr of loading while 31.51±1.02 MPa of NR/treated bundle-liked CaCO3 at filler loading 20 phr was obtained. The treated CaCO3-filled NR vulcanizates gave higher tensile strength than the untreated ones. This was caused by better compatibility of filler dispersion between the hydrophobicity of treated CaCO3 and hydrophobic property of NR. As a result, it was found that the NR filled with untreated fiber CaCO3 particle provided the highest tensile strength of 31.66±1.80 MPa at 10 phr of filler loading, over other types of CaCO3. The nanoparticle, large surface area, and high aspect ratio of fiber/ long nano wired of CaCO3 enhanced the interfacial adhesion between CaCO3 and NR matrix which could transfer stress from rubber to filler effectively during stretching. This resulted in the reinforcing efficacy of the fiber CaCO3. In summaroze, the prepared CaCO3 powders have the potential to broaden their application not only as diluents or additives but also as reinforcing agents