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Studies on Physical Chemistry of Rubber-Rice Husk Ash Composites
No full textNowadays an alternate source of filler from renewable and plant derivatives are being thought of in rubber industries due to their reliability, environmental and economic benefits. Rice Husk Ash (RHA) a byproduct of the rice milling industry is obtained on partial and as well as full combustion of the rice husks. This ash is a good source of silica, silicates and needle shaped carbon and hence can be used as filler for cements. In the present study, a detailed investigation was carried out to understand the RHA as reinforcing material using mechanical properties and fractography using SEM. The rubbers studied were natural rubber (NR), poly chloroprene (CR) and ethylene propylene diene monomer (EPDM). Interestingly, the RHA added NR stock on open mill mixing generated considerable amount of static charges. The properties of NR were found to be as good as regular formulations. EPDM compounds behaved well during mixing. But the properties were found to be poor. CR- RHA compounds were found to result in higher viscosity and the properties were not as good. The SEM studies showed surprisingly cohesive failure as evidenced with the presence of flow lines and the fibrous filler (RHA) remains embedded in the matrix regardless of the chemistry of the repeating unit, NR, EPDM and the chlorine containing monomer inCR
Leaves Based Lubricant Additive Towards Improving Tribological Properties
No full textThree kinds of crop leaf-surface waxes were extracted from wheat, corn and broomcorn leaves, respectively. The crop leaf-surface waxes as lubricant additives were added to synthetic ester and the friction and wear properties of prepared lubricants for steel-aluminum and steel-copper friction pair were investigated in detail. The scanning electron microscopy (SEM) and secondary ion mass spectrometry (SIMS) were employed to explore the friction mechanisms. The results show that crop leaf-surface waxes could successfully reduce the friction and wear of steel-aluminum and steel-copper sliding friction pairs as compared with pure synthetic ester. For example, when the concentration of wheat leaf-surface wax as additive was 2%, the COFs was decreased by 58%; the four additives can be ranked by the anti-wear capability as follows: Corn > Wheat > Glycerol >Broomcorn to steel-aluminum sliding friction pairs. The SIMS spectra of positive and negative ions on the worn surfaces have reduced the exposure of Al and increased short chain ions counts. The good friction reduction and antiwear abilities are attributed to the adsorption or reaction films formed by leafsurface wax on worn surface
Prediction of Thermal Conductivity and Specific Heat of Native Maize Starch and Comparison with HMT Treated Starch
No full textSpecific heat (Cp) and effective thermal conductivity (λ) of native maize starch (NS) were measured by DSC and transient heat transfer method, respectively, at different moisture contents and temperatures. The dependency of temperature (T) and moisture content (W) on the two parameters were investigated. The thermophysical properties of treated starch (TS) by four hydrothermal processes (RP-HMT, IV-HMT, DV-HMT and FV-HMT) were measured and compared to native strach. Hydrothermal treatments were performed at 3 bars (133°C) for 10 min. For Cp and λ measurements, moisture content varied for NS from 5 to 21.5% d.b. and from 8.8 to 25% d.b., respectively, and was fixed at 6% d.b. for TS. Empirical models were developed to specific heat and effective thermal conductivity, using a multiple regression algorithm with subsequent statistical analysis. The proposed models for NS based on T and W predict Cp and λ with a mean absolute error of 3.5% and 1.3%, respectively. Large differences in specific heat were observed between TS and NS. In a temperature range of 40 to 160°C, Cp values varied from 1.964 to 2.699 for NS and 1.380 to 2.085 (J.g-1.°C-1) for TS. In contrast, the conductivity of NS was almost identical to that of treated starch by FV-HMT, followed in an increasing order by those treated by DV-HMT, RP-HMT, and IV-HM processes
Recent Development of Cardanol Based Polymer Materials-A Review
No full textPolymers from renewable resources are receiving tremendous attention due to the increasing concerns on the depletion of fossil oils and deteriorated environments. Cardanol, as an abundant and renewable chemical raw material, has been widely used for the production of renewable polymer materials via converting into various of chemical monomers with active functional groups. This comprehensive review deals with various aspects of cardanol as a starting material the preparing various polymer and polymer composites such as benzoxazine resins, phenolic resin, polyurethanes, epoxy resin, vinyl ester polymers, polyamide and cyanate ester resins. The assessment of the future prospects for the use of cardanol to synthesise novel and valuable renewable materials is presented
Synthesis of Water-Soluble Chitosan From Squid Pens Waste for Capsule Shell Materials
No full textWater-Soluble Chitosan (WSC) has been sucessfuly synthesized from squid pens waste. The synthesis of chitosan from chitin was carried out by optimization of deacetylation temperature and time. Chitin was obtained from squid pens waste by demineralization and deproteinization process. HCl 7% was used for demineralization and NaOH 10% at 60°C was applied for deproteinization process. Deacetylation reaction was carried out at varied temperatures i.e., 60°C, 70°C, 80°C, 90°C and 100°C in NaOH 50% solution for 10 hours. Deacetylation reaction time were varied for 2 hours, 4 hours, 6 hours, 8 hours, and 10 hours. The crude chitosan obtained then reacted with H2O2 30% to depolymerize. The synthesis product obtained then characterized by FTIR. The result of squid chitin yield was 33.9%. The optimum temperature and time of chitosan deacetylation process were 90°C for 8 hours as indicated by the value of deacetylation degree (DD) that equal to 83.94% at optimum temperature and 82.22% at optimum reaction time. The percentage of WSC yield at optimum temperature (90°C) and optimum time (8 hours) were 27.59% and 23.16%, respectively. WSC solubility test was done in water and HCl 0,1N. The solubility of 2.8325 mg/mL and 0.8125 mg/mL were obtained in acid medium and water medium, respectively
Influence and Dispersion of Nanofiber of Wood Modified on Properties of Cement Based Mortars
No full textWood nanofibers from industrial waste have been used as polymeric material to reinforce the cement paste to a content of up to 2% by weight of cement. The effect of the wood nanofibre content on the porosity, the compressive strength and the degree of hydration of the cement was studied. The results showed an improvement in compressive strength of over 50% with 1% of added fiberwood. Chemical modification of nanofiber wood by grafting alkyl chains to their surface can reduce the amount of water absorbed by the sample. Addition of an anionic additive (SDBS) to the mixing water improves the surface of the samples more and more by minimizing the pore size by emulsion effect, hence the water absorption decreases. The degree of hydration of the cement increased with the cellulose content containing nanofibrils. The analysis revealed that the presence of nanofibers favored the hydration of the cement by producing more calcium silicate gel and portlandite, probably the main reason for this improvement in compressive strength
Evaluation of Mechanical Properties of Cross-Laminated Timber with Different Lay-ups Using Japanese Larch
No full textJapanese larch is one of the main plantation tree species in China. A lack of engineered wood products made by Japanese larch , limits its application in wood structures. In this study, based on optimum process para meters, such as pressure (1.2 MPa), adhesive spread rate (200 g/m 2 ) and adhesive (one component polyurethane), the mechanical properties of Japanese larch made cross laminated timber ( with different lay ups were evaluated by means of the static method . Results of this study show ed that variations in lay ups significant ly affected the mechanical properties of CLT. The strength and modulus of bending and parallel compression for CLT increased with the thickness of lumber w hile that o f bending, parallel compression and rolling shear all decreased with the number of layers. Thickness, layup orientation and the number of layers all had an impact on the strength of CLT. Failure modes obtained from numerical simulation w ere basically the s ame as th ose of expe rimental test s . There was also strong alignment between theoretical value and test value for effective bending stiffness and shear stiffness. Thus, the shear analogy method can be used to predict the mechanical properties of CLT effecti vely. This study pro ve d great potential in using Japanese larch wood for manufactur ing CLT due to its good mechanical propertie
Applying Neural Networks for Tire Pressure Monitoring Systems
No full textA proof-of-concept indirect tire-pressure monitoring system is developed using artificial neural networks to identify the tire pressure of a vehicle tire. A quarter-car model was developed with MATLAB and Simulink to generate simulated accelerometer output data. Simulation data are used to train and evaluate a recurrent neural network with long short-term memory blocks (RNN-LSTM) and a convolutional neural network (CNN) developed in Python with Tensorflow. Bayesian Optimization via SigOpt was used to optimize training and model parameters. The predictive accuracy and training speed of the two models with various parameters are compared. Finally, future work and improvements are discussed
Analysis of the Influence of Viscosity and Thermal Conductivity on Heat Transfer By Al<sub>2</sub>O<sub>3</sub>-Water Nanofluid
No full textThe addition of nanoparticles into liquid, even at low concentrations, leads to an increase in both, dynamic viscosity and thermal conductivity. Furthermore, the increase in temperature causes an increase in thermal conductivity and a decrease in the nanofluid viscosity. In this context, a numerical investigation of the competition between viscosity and thermal conductivity about their effects on heat transfer by Al2O3-water nanofluid was conducted. A numerical study of heat transfer in a square cavity, filled with Al2O3-water nanofluid and heated from the left side, was presented in this paper. Continuity, momentum, and thermal energy equations are solved by the finite volume method. Regarding the pressure-velocity coupling, the SIMPLER algorithm was used. The working conditions, allowing the increase of heat transfer, are established. In addition, two correlations for viscosity and thermal conductivity of Al2O3-water nanofluid as functions of the concentration and diameter size based on experimental measurement are proposed. These correlations were more precisely compared to those given by the theoretical models. Moreover, other models for viscosity and conductivity depending on temperature are used and discussed. The results reveal that heat transfer by Al2O3-water nanofluid is enhanced only when the temperature exceeds 40°C and the diameter size does not exceed a certain limit of the order of 45-50 nm depending on temperature
Analysis of the Impact of the Space Guide Vane Wrap Angle on the Performance of a Submersible Well Pump
No full textIn order to study the influence of the wrap angle relating to the space guide vane of a submersible well pump (250QJ125) on the flow field and pump performance, seven possible configurations have been considered (obtained by changing the blade wrap angle while keeping unchanged all the other parameters). Such configurations have been numerically simulated in the framework of a computational model based on the Reynolds time-averaged N-S equations, the RNG k-ε turbulence approach and the SIMPLE algorithm. The impact exerted by different wrap angles of the guide vane on the performance of the pump, the internal losses of the guide vane and the flow field distribution in the bladeless area at the guide vane outlet has been assessed via cross- comparison of all these cases. The results show that the wrap angle has a significant influence: the wrap angle with the highest head is different from that with the highest efficiency, and changes in this angle have a more significant effect on the head than efficiency. A moderate raise of the wrap angle can improve the properties of the flow, reduce turbulence losses and enhance the energy conversion rate inside the guide vane. Different wrap angles can also lead to different fluid circulation modes in the bladeless area from guide vane outlet to impeller inlet, while they have a weak influence on the absolute value of the velocity of the fluid entering the impeller