DRYING KINETICS AND CROSS-LINKING OF SULFUR PREVULCANIZED THICK NATURAL RUBBER LATEX FILM

2013 ◽  
Vol 86 (1) ◽  
pp. 57-67 ◽  
Author(s):  
Chen Jing ◽  
Yang Lei ◽  
Zhong Jieping ◽  
Li Sidong ◽  
Chen Yongjun ◽  
...  
Keyword(s):  
Film Formation ◽  
Natural Rubber Latex ◽  
Type Equation ◽  
Drying Kinetics ◽  
Latex Film ◽  
Cross Linking ◽  
Drying Time ◽  
Drying Temperature ◽  
Drying Kinetic ◽  
Link Density

ABSTRACT In order to investigate drying kinetics of thick natural latex (NR) samples after film formation and the effect on cross-linking of NR latex during the drying process, we employed drying experiment methods, swelling methods, and Fourier transform infrared spectroscopy (FTIR) methods to study the drying and vulcanizing characteristics of NR latex. The results show that the drying temperature and thickness of film have obviously affected drying characteristics. The drying kinetic equation is achieved by mathematic fitting, and the Henderson and Pabis model MR = a exp(−kt) was the best fitted model for the thick NR latex film. The effect of the drying temperature on the drying constant was assessed employing an Arrhenius type equation, which can be expressed as k = 6746 exp[−39.9 × 103/(RT)] (R = 8.314 J mol−1 K−1). The drying constant exponentially decreased with the increasing film thickness. At the beginning of drying, the cross-link density increases rapidly, and up to the maximum value, it would slightly decrease with the prolonged drying time, which the results of FTIR also agree with.

scholarly journals Physicochemical, Thermomechanical, and Swelling Properties of Radiation Vulcanised Natural Rubber Latex Film: Effect of Diospyros peregrina Fruit Extracts

2013 ◽  
Vol 2013 ◽  
pp. 1-8
Author(s):  
Kazi Md Zakir Hossain ◽  
Nashid Sharif ◽  
N. C. Dafader ◽  
M. E. Haque ◽  
A. M. Sarwaruddin Chowdhury
Keyword(s):  
Natural Rubber ◽  
Natural Rubber Latex ◽  
Tensile Modulus ◽  
Decomposition Temperature ◽  
Latex Film ◽  
Cross Linking ◽  
Rubber Latex ◽  
Swelling Properties ◽  
Fruit Extracts ◽  
Control Film

A range of radiation vulcanised natural rubber latex (RVNRL) films were prepared using various concentrations of aqueous extracts of mature Diospyros peregrina fruit, which acted as a cross-linking agent. The surface of the RVNRL films exhibited an aggregated morphology of the rubber hydrocarbon with increasing roughness due to increasing fruit extract contents in the latex. An improvement in tensile strength, tensile modulus, and storage modulus of RVNRL films was observed with the addition of fruit extracts compared to the control film due to their cross-linking effect. The glass transition (Tg) temperature of all the RVNRL films was found to be at around −61.5°C. The films were also observed to be thermally stable up to 325°C, while the maximum decomposition temperature appeared at around 375°C. The incorporation of fruit extracts further revealed a significant influence on increasing the crystallinity, gel content, and physical cross-link density of the RVNRL films.

scholarly journals Impact of citric acid on the drying characteristics of kiwifruit slices

2020 ◽  
Vol 42 ◽  
pp. e40570
Author(s):  
Ibrahim Doymaz
Keyword(s):  
Regression Analysis ◽  
Citric Acid ◽  
Effective Diffusivity ◽  
Type Equation ◽  
Moisture Diffusion ◽  
Moisture Diffusivity ◽  
Diffusivity Coefficient ◽  
Drying Time ◽  
Drying Temperature ◽  
Drying Behaviour

Kiwifruit slices were dried at four different air drying temperatures of 50, 55, 60 and 70ºC and at 2 m s-1 air velocity by using a cabinet dryer in this study. The drying, rehydration and colour characteristics were significantly influenced by pretreatment and drying temperature. The drying time decreased with the increase in drying temperature. The drying rate curves showed that the entire drying process took place in the falling rate period. Five well-known thin-layer models were evaluated for moisture ratios using nonlinear regression analysis. The results of regression analysis indicated that the Midilli & Kucuk model the best to describe the drying behaviour with the lowest c2 and RMSE values, and highest R2 value. The effective moisture diffusivity of the dried kiwifruit slices was calculated with Fick’s diffusion model, in which their values varied from 4.19×10–10 to 6.99×10-10 m2 s-1 over the mentioned temperature range. The dependence of effective diffusivity coefficient on temperature was expressed by an Arrhenius type equation. The calculated values of the activation energy of moisture diffusion were 10.37 and 19.08 kJ mol-1 for citric acid and control samples, respectively

Comparison of Drying Kinetics of Maize in Oven and in Pilot Silo Dryer: Influence on Moisture Content and Physical Characteristics

2016 ◽  
Vol 12 (6) ◽  
pp. 599-606 ◽  
Author(s):  
Flávia Daiana Montanuci ◽  
Raphaela Mulato Cavalcante ◽  
Camila Augusto Perussello ◽  
Luiz Mario de Matos Jorge
Keyword(s):  
Moisture Content ◽  
Temperature Increase ◽  
Drying Kinetics ◽  
Final Moisture Content ◽  
Drying Rate ◽  
Drying Time ◽  
Drying Temperature ◽  
Design And Optimization ◽  
Process Kinetics ◽  
Kinetics Of

Abstract The study of process kinetics may aid the design and optimization of drying systems. This paper evaluated the influence of drying temperature (40, 60 and 80 °C) on the moisture content, drying rate, density, shrinkage and breakage of maize dried in two different dryers: oven and silo dryer. In both dryers, the temperature increase reduced drying time, final moisture content and shrinkage of the grains, however increased breakage. Drying rate was higher in the oven (6.4×10−4±2.3×10−4s−1 versus 5.4×10−4±1.2×10−4s−1), while shrinkage (15.2±4.7 % versus 24.4±5.6 %) and density increase (16.6±5.9 % versus 33.4±5.8 %) were more intense in the silo. There was a large release of husk in the silo dryer and the moisture content was slightly smaller in the lower layers respective to the upper ones.

scholarly journals The Experimental Research of Drying Kinetics of Nagpur Orange Fruit (Citrus Sinesis- L) by Hot Air Electrical Dryer

2019 ◽  
Vol 8 (6S4) ◽  
pp. 1131-1134
Keyword(s):  
Thin Layer ◽  
Drying Kinetics ◽  
Drying Time ◽  
Drying Characteristics ◽  
Drying Temperature ◽  
Hot Air ◽  
Thin Layer Drying ◽  
Drying Behavior ◽  
Orange Fruit ◽  
Kinetics Of

The study is aimed experimentally and compared with the theoretical results of drying kinetics of Nagpur orange fruit dried in a hot air electrical dryer. Orange fruit is highly perishable and needs to be consumed or processed immediately after harvest. Drying or dehydration is one of the most practical methods of preserving food products. Therefore, thin layer drying characteristics of falling rate of Nagpur orange are determined experimentally under different conditions of drying air temperatures, relative humidity and air velocities for different moisture contents. Thin layer models like Wang and Singh, Page and Henderson have been compared with Experimental results. The knowledge of drying kinetics helps for identification of exact drying time and air flow velocity for different moisture content. Here drying operation is carried out at a velocity of 1m/sec and 1.25 m/sec for different temperature of 55°C, 65°C and 75°C. This analysis reveals that drying temperature has a more significant effect on moisture removal while velocity has the least effect. Drying rate is found to increase with the increase in drying temperature and reduce with drying time. Experimental data is statistically correlated by plotting the drying characteristics curve. The analysis reveals that Wang and Singh's model is a better model to explain the drying behavior of Nagpur Orange fruit (R2=0.9888).

scholarly journals Drying kinetics and thin layer modeling of ogi produced from six maize varieties at varying soaking period and drying temperature

Food Research ◽  
2021 ◽  
Vol 5 (1) ◽  
pp. 431-440
Author(s):  
O.T. Bolaji ◽  
P.A. Adepoju ◽  
E.O. Adelana ◽  
B.S. Adesina
Keyword(s):  
Activation Energy ◽  
Moisture Content ◽  
Thin Layer ◽  
Research Work ◽  
Initial Moisture Content ◽  
Moisture Diffusivity ◽  
Drying Kinetics ◽  
Drying Time ◽  
Drying Temperature ◽  
Maize Varieties

The drying kinetics of ogi produced from six varieties of maize at varying soaking period (12, 24 and 36 hrs) and drying temperature of 40, 50 and 60oC, respectively were studied. Seven common thin layer models were evaluated, and the best models were selected. The moisture content of ogi decreased with increased drying temperature and drying time while the drying rate increased with an increase in drying temperature and decreased with an increase in drying time. Logarithmic and two term models best fitted about 40.77% (22 samples each). However, where two term models were selected best, the R2 values ranged from 0.9858-0.99999999, χ 2 = 0.03715-0.000412, RMSE = 0.02206-0.0000677, unlike Logarithmic model that ranged from 0.8876-0.9964, χ 2 = 0.07045-0.001447, RMSE = 0.1084-0.01098. There was no definite pattern for effective moisture diffusivity (Deff) and Activation energy (Ea). This research work strongly suggests that the drying process was predominantly in the falling rate period (FRP) and was significantly affected by the change in temperature and moisture gradient. The activation energy obtained for ogi at varying soaking period and drying temperature ranged from 2.58-12.00 kJ/mol (A4Y), 7.72-44.95 kJ/mol (A4W), 14.53-35.88 kJ/mol (S7Y), 6.02-20.10 kJ/mol (D2Y), 14.024- 45.31 kJ/mol (DIY) and 19.34-64.22 kJ/mol (T3W). It was obviously indicated in this research that the soaking period had less or no impact on the drying behavior of ogi compared with the influence of drying temperature, drying time and initial moisture content.

scholarly journals Convective Hot Air Drying of Chilli Pepper: Process Optimization and Modelling the Drying Kinetics and Quality Attributes of Dried Product

2020 ◽  
Author(s):  
Felix Ajuebor ◽  
Oluwafunmilayo Aworanti ◽  
Oluseye Agbede ◽  
Samuel Agarry ◽  
Tinuade Afolabi ◽  
...  
Keyword(s):  
Quality Attributes ◽  
Drying Kinetics ◽  
Interactive Effects ◽  
Optimum Process ◽  
Process Conditions ◽  
Air Velocity ◽  
Chilli Pepper ◽  
Drying Time ◽  
Drying Temperature ◽  
Hot Air

Abstract The objectives of this study were to evaluate the individual and interactive effects of air velocity, relative humidity, drying temperature, and drying time on the cabinet hot air drying and quality attributes of chilli pepper as well as to determine the optimum process conditions using the rotatable central composite design (RCCD) of response surface methodology (RSM). The drying kinetics was also modelled. Four factors with three levels of RCCD were utilized: air velocity (0.5-1.5 m/s), relative velocity (65-75%), drying temperature (50-70 o C), and drying time (180-360 min). Product moisture content (PMC), total plate count (TPC), protein content (PC), and carbohydrate content (CC) were evaluated as the quality attributes (responses). The results showed that the drying experimental data significantly ( p ≤ 0.001) and adequately fitted into second-order quadratic regression models with (>0.95) to describe and predict all the responses. Drying time and drying temperature are the most significant drying conditions that exerted more pronounced linear and interactive effects on the dried chilli pepper quality attributes. The predicted optimum process conditions for the production of dried chilli pepper with minimum PMC and TPC as well as maximum PC and CC were obtained to be: drying temperature, 69.98 o C, air velocity, 1.46 m/s, relative humidity, 66.57%, and drying time, 359.86 min. Four empirical models (Page, Newton, Logarithmic, and Henderson and Pabis) were fitted to the drying data and the Page model with (>0.95) best fitted the data to describe the drying kinetics.

scholarly journals Grafting of n-butyl acrylate with natural rubber latex film by gamma radiation: a reaction mechanism

1970 ◽  
Vol 5 (1) ◽  
pp. 81-88 ◽  
Author(s):  
KMZ Hossain ◽  
AM Sarwaruddin Chowdhury
Keyword(s):  
Reaction Mechanism ◽  
Natural Rubber ◽  
Butyl Acrylate ◽  
Natural Rubber Latex ◽  
Latex Film ◽  
Cross Linking ◽  
Swelling Ratio ◽  
Cross Link ◽  
Rubber Latex ◽  
The Cross

Natural rubber latex (NRL) and n-butyl acrylate (n-BA) were blended and irradiated at various absorbed doses by gamma rays from Co-60 source at room temperature. The stabilizing effect was determined by measuring the pH and viscosity of NRL with n-BA with the storage time of five weeks. The cross-link density, swelling ratio of the radiation vulcanized rubber film were measured. The cross-link density of the n-BA grafted NRL film was found increasing and the swelling ratio of that film decreasing with the increased absorbed dose. The optimum radiation dose for better cross-linking of natural rubber latex blended with five parts per hundred rubber (phr) n-BA was found 15 kGy absorbed dose. Based on the cross-linking properties a probable cross-linking reaction mechanism for the n-BA grafted natural rubber latex film was developed. Keywords: Natural rubber latex, n-butyl acrylate, Irradiation, Swelling ratio, Cross-link, Reaction mechanism. DOI: 10.3329/diujst.v5i1.4386 Daffodil International University Journal of Science and Technology Vol.5(1) 2010 pp.81-88

scholarly journals Mathematical modeling and thermodynamic properties in the drying of citron watermelon seeds

2022 ◽  
Vol 26 (1) ◽  
pp. 67-74
Author(s):  
Daniela D. de F. Leite ◽  
Alexandre J. de M. Queiroz ◽  
Rossana M. F. de Figueirêdo ◽  
Francislaine S. dos Santos ◽  
Semirames do N. Silva ◽  
...  
Keyword(s):  
Thermodynamic Properties ◽  
Effective Diffusivity ◽  
Type Equation ◽  
Titratable Acidity ◽  
Drying Kinetics ◽  
Agricultural Product ◽  
Air Velocity ◽  
Drying Temperature ◽  
Physicochemical Composition ◽  
Nutritional Characteristics

ABSTRACT Citron watermelon is an agricultural product of excellent economic potential. Its seeds are widely used for oil extraction, serving as an energy source, showing nutritional characteristics that make them a suitable product to be studied. Thus, the objective was to characterize citron watermelon seeds regarding their physicochemical composition, in addition to determining drying kinetics, fitting mathematical models to the data, and determining the effective diffusivity coefficients and thermodynamic properties. The seeds were dried in a convective dryer, varying the drying temperature, with air velocity of 1.0 m s-1. With the increase in drying temperature, there were reductions in moisture content, water activity (aw), ash concentration, total titratable acidity, lipids and reducing sugar. Citron watermelon seeds are rich in lipids and ash, have low sugar concentration and low acidity; their drying kinetics was very well described by the Two Terms and Approximation of Diffusion models, followed by the models of Midilli and Page, which resulted in acceptable fits. Effective diffusivity accompanied the increase in drying temperature, and this behavior was well fitted by an Arrhenius-type equation. Enthalpy and entropy variations were reduced with drying temperature, with increments in Gibbs free energy.

scholarly journals Modelling the Thin-Layer Drying Kinetics of Untreated and Blanch-Osmotic Pre-treated Tomato Slices

2016 ◽  
Vol 4 (10) ◽  
pp. 850 ◽  
Author(s):  
Samuel Enahoro Agarry
Keyword(s):  
Linear Regression Analysis ◽  
Drying Kinetics ◽  
Coefficient Of Determination ◽  
Drying Rate ◽  
Drying Time ◽  
Drying Temperature ◽  
Hot Air ◽  
Thin Layer Drying ◽  
Pre Treatment ◽  
Air Dryer

The objective of this study was to investigate the effect of pre-treatment and drying temperature on the drying kinetics and nutritional quality of tomato (Lycopersicon esculantum L.) under hot air drying. Tomato samples were blanched at 80oC and osmotically dehydrated using 20% w/w sodium chloride solutions at 30oC for 20 min. The blanch-osmotic pre-treated and untreated tomato slices were dried at temperature of 40, 50, 60, 70 and 80oC, respectively in a hot air-dryer. The results showed that blanch-osmotic pre-treatment offered a higher drying rate and lower or faster drying time than untreated condition. The tomato drying regime was characteristically in the constant and falling rate period. The tomato drying rate curve showed characteristics of porous hygroscopic solids. The optimum drying temperature for tomato was found to be 60oC. Four semi-empirical drying models of Newton, Page, Henderson and Pabis, and Logarithmic were fitted to the drying data using non-linear regression analysis. The most appropriate model was selected using the coefficient of determination (R2) and root mean square error (RMSE). The Page model has shown a better fit to the drying kinetics data of tomato in comparison with other tested models. Transport of moisture during drying was described by Fick’s diffusion model application and the effective moisture diffusivity (Deff) thus estimated. The Deff at 60oC was 4.43 × 10-11m2/s and 6.33 × 10-11m2/s for blanch-osmotic pre-treated and untreated tomato slices, respectively.

scholarly journals Effects of Vacuum Drying on Structural Changes of Banana Slices

2013 ◽  
Vol 13 (1) ◽  
pp. 1 ◽  
Author(s):  
Wannapit Junlakan ◽  
Ram Yamsaengsung ◽  
Supawan Tirawanichakul
Keyword(s):  
Optimum Condition ◽  
Thin Layer ◽  
Chamber Pressure ◽  
Vacuum Drying ◽  
Drying Time ◽  
Drying Temperature ◽  
Overall Acceptability ◽  
Thin Layer Drying ◽  
Drying Kinetic ◽  
Drying Condition

The objective of this research was to study the optimum condition for the vacuum drying of banana slices using a vacuum dryer and to find out the appropriate thin layer equation for predicting the drying kinetic of bananas. The experiments were carried out at the drying temperatures of 60, 70, 80 and 90oC and absolute chamber pressure of 30 mmHg. The drying experiments were performed until the samples moisture content was lower than 3.4% (w.b.). Next, the dried products were analyzed for physical quality (in terms of color, shrinkage, and texture) and sensory quality (in terms of color, texture, flavor, crispness and overall acceptability). These data were used in choosing the optimum condition for the vacuum drying of banana slices. From experimental results, the drying time at the highest drying temperature was the shortest. At this condition, the dried banana slices showed the highest degree of yellowness, lower shrinkage, and more crispness compared to lower drying temperatures. From sensory analysis, each drying condition showed significant effect on consumer acceptability with the drying temperature of 70, 80 and 90oC showing the levels of the overall acceptability sensory qualities of dried banana is not significantly different. Consequently, the drying temperature of 90oC was suggested as the best drying condition for sliced bananas. Moreover, three mathematical models (Newton, Logarithmic and Page) describing thin layer drying were investigated. It was found that the thin layer equation providing the highest coefficient of determination (R2) and the lowest chi-square (X2) and root mean square error (RMSE) was the Logarithmic equation.

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