Nano Kaolin Research Articles

Preparation and characterization of bionanocomposite films reinforced with nano kaolin.

Effects of nano-kaolin incorporation into semolina films on the physical, mechanical, thermal, barrier and antimicrobial properties of the resulting bio-nanocomposite films were investigated. The properties included crystal structure (by X-ray diffraction), mechanical resistance, color, Fourier transform infrared spectra, decomposition temperature, water-vapor permeability (WVP), oxygen permeability (OP), and antimicrobial activity against Staphylococcus aureus and Escherichia coli. Kaolin was incorporated into biofilms at various amounts (1, 2, 3, 4, and 5%, w/w total solid). All films were plasticized with 50% (w/w total solid) combination of sorbitol/glycerol at 3:1 ratio. The incorporation of nanokaolin into semolina films decreased OP and WVP. The moisture content and water solubility of the films were found to decrease by nanokaolin reinforcement, and mechanical properties of films were improved by increasing nanokaolin concentration. Tensile strength and Young's modulus increased from 3.41 to 5.44MPa and from 63.12 to 136.18, respectively, and elongation-at-break decreased. The films did not exhibit UV absorption. In conclusion, nanokaolin incorporation enhanced the barrier and mechanical properties of semolina films, indicating the potential application of these bio-nanocomposites in food-product packaging.

Fresh State Behaviour of Cement Paste Containing Nano Kaolin

The application of nanomaterials in cement by replacement method in concrete is becoming a trend in cement research. The utilisation of nanosilica, nanoalumina, titanium oxide and others are proven to enhance properties of concrete. The major effect of nanomaterials is its size in which it contributes to the packing theory due to increase in the surface area. nanokaolin which comes from kaolin, was tansformed to the nanoform by using high energy milling. The process of developing nanokaolin by using high energy milling is referred to process top to bottom approach in nanoprocessing technique. In this research, the nanokaolin will be used as an additive in cement by 7% weight of cement. Four (4) cement replacement materials catered by using metakaolin on weight basis from 0, 10%, 20% and 30% will also be adopted. To determine the fresh state, cement paste contains nanokaolin and metakaolin are tested its standard consistency and setting time. The effect of the inclusion of the nanokaolin as additive in cement paste that also contains metakaolin as cement replacement material will be investigated. It was found the inclusion of 7% nanokaolin increases the water demand of the cement paste level of metakaolin replacement. In addition to that, the setting time namely initial and final set was been delayed as compared to that of plain OPC. The nanoparticles of nanokaolin and also finer particles of metakaolin increase the surface area and refining the internal structure of cement paste which reduce the flow capabilities of cement paste containing nanokaolin and metakaolin.

Pozzolanic and hydraulic activity of nano-metakaolin

Nano-metakaolin (NMK) was prepared by firing of Nano-kaolin (NK) at different temperatures (750–825°C) for 2h. The pozzolanic activities of NMK samples were studied using hydrated lime as an activator. The optimum firing temperature of metakaolin (MK) was established from the results of hydration kinetics and differential scanning calorimetry (DSC) and found to be 750°C; NMK, thus produced, is designated as NMK(750). This was based on the marked consumption of free calcium hydroxide by NMK fired at 750°C as well as the highest values of chemically combined water at all ages of hydration. Therefore, NMK(750) was used for partial replacement of OPC and studying the physico–mechanical properties of OPC–NMK blended cement pastes. The optimum substitution of OPC by NMK was found to be 8–10%. This was based on the development of compressive strength of the various hardened OPC–NMK blended cement pastes having different NMK contents (0–16%), where the strength increases with NMK content up to 10% and then decreases. In addition, the SEM micrographs obtained for the hardened OPC (93%)–NMK (7%) blended cement paste displayed the formation of amorphous and microcrystalline CSH which fill the pores leading to a more dense structure with higher hydraulic activity as compared to neat OPC paste.

Sol Gel Characterization of Nano Kaolin

Nano kaolin is product from kaolin also known as white clay. Kaolin was established as supplementary cementitious materials in concrete. The inclusion of kaolin in concrete enhances strength and durability properties and prolongs concrete life span. In this research, nanokaolin will be develop by using sol gel technique by that involves high energy milling. The process of milling been influenced by time of milling, ball and jar type. Ceramic type Zirconia (Zi) is been used as jar and ball type in this process. Time of milling was set from four (4) hours and one (1) days. Sample will be analyse by using particle size analyser to see the particle size and surface area of kaolin. From the result shows the optimum milling period for nanokaolin is one day base on particle size compare to 4 hours. Furthermore, one day milling produces a massive increment of surface area compare to others. In conclusion, one day can be considered as the optimum cycle time in the production of nano kaolin.

Physico-mechanical characteristics of blended white cement pastes containing thermally activated ultrafine nano clays

The aim of this work is to produce highly active and amorphous nano sized pozzolana by means of thermal activation of nano clays and to utilize the thermally activated nano clays as additives in white Portland cement pastes (WPC) to improve their thermo mechanical properties. Nano-kaolin was thermally treated at 750°C for 2h to get active activated nano-metakaolin (NMK). The effect of thermal activation on the dehydroxylation of the nano-kaolin was determined by using different techniques such as; X-ray diffraction spectroscopy (XRD) and differential thermal analysis (DTA). The surface morphologies of both nano-kaolin and NMK were studied by transmission electron microscopy (TEM).NMK were incorporated at a rate of 2%, 4%, 6%, 8%, 10%, 12% and 14% by weight of cement. Hardened blended cement pastes were prepared by using water/cement ratio (W/C) of 0.3 by weight and hydrated for various curing ages 3, 7 and 28days. In order to study the mechanical and physical characteristics of the hardened cement pastes incorporating NMK, different techniques were used such as compressive and flexural strength testing, differential scanning calorimeter (DSC), X-ray diffraction (XRD) and scanning electron microscope (SEM). The experimental results of this study showed that thermal activation of the nano kaolin leads to transformation of the kaolinite to amorphous phase accompanied with the reduction in grain size. The partial replacement of cement by NMK is helpful in enhancing the compressive and flexural strength of cement products. There was an enhancement of compressive strength by about 50% and flexural strength by 36% at 10% nanoclay. The microstructure of the cement blended with NMK was denser, compact and more uniform than that of the conventional cement.

Thermo-Mechanical Characteristics of Blended White Cement Pastes Containing Ultrafine Nano Clays

Abstract The aim of this work was to produce highly active and amorphous nano sized pozzolana by means of thermal activation of nanoclays and to utilize the thermally activated nanoclays as additives in white Portland cement pastes (WPC) to improve their thermo mechanical properties. The nanoclay used in this investigation is kaolin clay. The nano Kaolin was thermally treated at 750°C for 2 h to obtain active amorphous nano metakaolin (NMK). The effect of thermal activation on the dehydroxylation of the kaolin and the surface morphology of the resulting amorphous NMK were determined by using different techniques: X-ray diffraction spectroscopy (XRD), differential thermal analysis (DTA) and Transmission electron microscopy (TEM). NMK were incorporated at a rate of 2, 4, 6, 8, 10, 12, and 14% by weight of cement. Hardened blended cement pastes were prepared by using water/cement ratio (W/C) of 0.3 by weight and hydrated for various curing ages 3, 7, and 28 days. In order to study the mechanical and physical characteristics of the hardened cement pastes incorporating NMK, different techniques were used such as compressive and flexure strength testing, differential scanning calorimeter (DSC), x-ray diffraction (XRD), and scanning electron microscope (SEM). The experimental results of this study showed that thermal activation of the nano kaolin leads to transformation of the kaolinite to amorphous phase accompanied with the reduction in grain size. The partial replacement of cement by NMK is helpful in enhancing the compressive and flexure strength of cement products. There was an enhancement of compressive strength by about 50% and flexure strength by 36% at 10% nanoclay. The microstructure of the cement blended with NMK was denser, compact, and more uniform than that of the conventional cement microstructure.

Behavior of blended cement mortars containing nano-metakaolin at elevated temperatures

The effects of high temperatures up to 800°C on the mechanical properties and microstructure of nano-metakaolin cement mortars were investigated in this study. The blended cement used in this investigation is ordinary Portland cement (OPC) containing nano-metakaolin (NMK). The nano-metakaolin was prepared by thermal activation of nano kaolin clay at 750°C for 2h. The mortar was prepared using blended cement: sand ratio of 1:3 and water/binder ratio of 0.6. The cement mortar pastes were cured under water for 28days; then dried at 105±5°C for 24h and then exposed to 250, 450, 600 and 800°C for 2h. The compressive and flexural strengths were measured for blended cement mortar and compared with the strength of pure OPC mortar. It was found that after an initial increase in compressive strength at 250°C for the mortar specimens, the strength decreased considerably at higher temperatures.

INVESTIGATION ON CRYSTALLIZATION AND MECHANICAL PROPERTIES OF POLY(BUTYLENE SUCCINATE)/NANO KAOLIN BLENDS

In order to improve the performance of poly(butylenes succinate)(PBS) like the crystallinity and mechanical properties,PBS/nano kaolin blends were prepared by mechanical melting mixing.The microstructure,crystallinity,mechanical properties and dispersion of the PBS/nano kaolin were studied respectively with infrared spectrometer(FTIR),differential scanning calorimeter(DSC),universal material testing machine and scanning electron microscope(SEM).Infrared spectra showed picture shown that the modifier could be bonded to nano kaolin.The DSC results indicated that the onset(denoted as To,c),peak(denoted as Tp,c) and end crystallization temperature(denoted as Te,c) of PBS were increased respectively.DSC melting curves for the melt-crystallized samples were obtained at 10 K min-1.Double endothermic peaks,a high-temperature peak H and a low-temperature peak L,and an exothermic peak located between them appeared.At the same time,the crystallization degree rose first and declined finally as the nano kaolin content increased.When the content of nano kaolin was decreased,the notched impact strength,elongation at break and tensile strength of PBS/nano kaolin blends were improved obviously.The SEM results showed that at low contents nano kaolin was dispersed evenly in the blends,while agglomeration of nano kaolin was observed in blends with increasing kaolin content.The improving of the mechanical performance of PBS/nano kaolin blends is correlated with the variation of nano kaolin content.

Properties of vulcanized rubber nanocomposites filled with nanokaolin and precipitated silica

One kind of nanokaolin (NK) powder with 20–50 nm average thickness, 300–500 nm average diameter, and 32 m 2/g specific surface area, has been introduced into four types of rubber, specifically styrene butadiene rubber (SBR), natural rubber (NR), butadiene rubber (BR) and ethylene–propylene diene methylene (EPDM). Their reinforcing effects were evaluated by comparisons with those from precipitated silica (PS). The curability, mechanical properties, microstructure and the thermal stability of a variety of composites based on these rubbers were studied. This was done using vulcanization techniques, mechanical testing, thermogravimetric analysis (TGA), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The results showed that NK can greatly improve the vulcanizing process by shortening the time to optimum cure ( t 90) and prolonging the setting-up time ( t 10) of cross-linked rubbers, which improves production efficiency and operational security. The rubber composites filled with nanokaolin were found to have good mechanical properties, thermal stabilities, and elastomeric properties. The tensile strengths of the rubber/NK composites are close to those of rubber/PS composites, but the tear strength and modulus are not as good as the corresponding properties of those containing precipitated silica. Microstructural results revealed that the NK sheets are well dispersed in the rubber matrix in the parallel arrangement. The good interfacial interactions between the NK and the rubber chains give these rubber composites excellent processability, mechanical properties, and thermal stability.