scholarly journals The effect of drying on the mechanical properties and structure of biodegradable films

2018 ◽  
Author(s):  
Gabriela Silveira da Rosa ◽  
Sai Vanga ◽  
Yvan Gariepy ◽  
Vijaya Raghavan
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Convective Drying ◽  
Vacuum Drying ◽  
Drying Rate ◽  
Biodegradable Films ◽  
Film Forming ◽  
Rate Period ◽  
Bovine Gelatin ◽  
Kinetics Of

The aim of this study was to investigate the effect of convective and vacuum drying on properties of biodegradable films. The film-forming solutions were prepared with bovine gelatin and carrageenan. The films solutions were dried in convective and vacuum dryers at temperatures of 40, 50 and 60 oC. The results of convective drying kinetics of biofilms showed a constant drying rate period followed by a falling drying rate period. The results of thickness showed dependence with moisture content present in films.Carrageenan films showed promising results, with high values of tensile strength and elongation for convective drying at 60 oC. Keywords: gelatin; carrageenan; drying; biofilm 

Effect of Pre-Treatment on the Drying Characteristics and Kinetics of Okra (Abelmoschus esculetus (L.) Moench) Slices

2009 ◽  
Vol 5 (2) ◽  
Author(s):  
Olajide Sobukola
Keyword(s):  
Air Temperature ◽  
Sample Thickness ◽  
Hot Water ◽  
Drying Rate ◽  
Diffusivity Coefficient ◽  
Drying Characteristics ◽  
Rate Period ◽  
Pretreatment Conditions ◽  
Air Dryer ◽  
Kinetics Of

The effects of air temperature (50, 60 and 70°C), sample thickness (2, 4 and 6mm) and pretreatment conditions (hot water blanching, 1 and 3% sodium metabisulphite solutions) on the drying characteristics and kinetics of okra were investigated using a convective hot air dryer at a flow rate of 1.5m/s. It was observed that pretreatment conditions, sample thickness and drying air temperature significantly (P<0.05) affected drying rate. Drying rate increases as temperature of drying air increases from 50 to 70°C. The drying curve for all experiments occurred in the falling rate period with no constant rate period. Three thin layer drying models (Page, modified Page I and Wang and Singh) were evaluated using coefficient of determination (R2), root mean square error (RMSE) and the reduced chi square (?2). The three models can appropriately describe the drying kinetics of okra slices considering the different experimental conditions. The effective diffusivity was determined using the Fick’s model and was observed to vary between 1.125x10-8 – 9.93x10-9m2/s and 1.165x10-8 – 7.131x10-9 m2/s for treated and untreated samples. The Arrhenius-type relationship describes the temperature dependence of diffusivity coefficient and was determined to be 16.749kJ/mol and 22.437kJ/mol for treated and untreated samples respectively.

scholarly journals Dynamic Cure Kinetics and Physical-Mechanical Properties of PEG/Nanosilica/Epoxy Composites

2020 ◽  
Vol 2020 ◽  
pp. 1-10 ◽  
Author(s):  
Haleh Nowruzi Varzeghani ◽  
Iraj Amiri Amraei ◽  
Seyed Rasoul Mousavi
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Cure Kinetics ◽  
Diglycidyl Ether ◽  
Solid Particles ◽  
Scanning Calorimetry ◽  
Cure Reaction ◽  
Cure Kinetic ◽  
Cure Temperature ◽  
Kinetics Of

This study investigated the effect of polyethylene glycol (PEG) and nanosilica (NS) on the physical-mechanical properties and cure kinetics of diglycidyl ether of bisphenol-A-based epoxy (DGEBA-based EP) resin. For this purpose, tensile and viscometry tests, dynamic mechanical thermal analysis (DMTA), and differential scanning calorimetry (DSC) were carried out under dynamic conditions. The results showed that adding NS and PEG enhances the maximum cure temperature as well as the heat of cure reaction (ΔH) in EP-NS, while it decreases in EP-PEG and EP-PEG-NS. The cure kinetic parameters of EP-PEG-NS were calculated by Kissinger, Ozawa, and KSA methods and compared with each other. The Ea calculated from the Kissinger method (96.82 kJ/mol) was found to be lower than that of the Ozawa method (98.69 kJ/mol). Also, according to the KAS method, the apparent Ea was approximately constant within the 10-90% conversion range. Tensile strength and modulus increased by adding NS, while tensile strength diminished slightly by adding PEG to EP-NS. The glass transition temperature (Tg) was calculated using DMTA which was increased and decreased by the addition of NS and PEG, respectively. The results of the viscometry test showed that the viscosity increased with the presence of both PEG and NS and it prevented the deposition of solid particles.

scholarly journals STUDYING THE PROPERTIES OF GRAPE POMACE AS OF AN OBJECT OF DRYING

2018 ◽  
Vol 12 (2) ◽  
Author(s):  
V. Derevenko ◽  
G. Kasyanov ◽  
L. Pylypenko
Keyword(s):  
Grape Pomace ◽  
Biologically Active ◽  
Raw Material ◽  
Convective Drying ◽  
Drying Rate ◽  
Drying Time ◽  
Rate Period ◽  
Fresh Frozen ◽  
Red Grape ◽  
Grape Varieties

Grape pomace contains a complex of valuable and biologically active compounds. Drying is one of the main ways of microbiological stabilisation and preservation of the nutritional value of this secondary raw material. Kinetic parameters of dehydration of grape pomace from different industrially cultivated and processed varieties have been studied, namely, of the red grape varieties Cabernet and Shiraz, and of the white varieties Chardonnay and Riesling. Dependences of the moisture content in the process of convective drying at different drying agent rates have been obtained at a regulated temperature of 80 °C. The components of such an important technological parameter as the drying time have been determined. These components include the duration of the constant drying rate period Φ2 and the time of the decreasing drying rate period Φ1 of the two zones of the second drying period. The coefficients of the dehydration process have been calculated depending on the type of grape pomace processing. It has been shown that the discrepancy between the calculated and experimental results does not exceed ±3.9%. The specific features of the moisture yield of the pomace have been revealed, the pomace being viewed as a complex heterogeneous system with colloidal and capillary-porous properties. There are different types of its technological preparation: it can be fresh, frozen, fermented, and this makes for the fact that the drying time and drying rate may differ by 1.32–1.46 times. High preservation of valuable properties of grape pomace has been shown. Thus, the concentration of biologically active substances (BAS) in the total polyphenolic compounds is up to 69% of their initial concentration in the grape pomace samples, and the microbial contamination of the samples after drying is reduced by 51–82% of their initial contamination.

scholarly journals Effect of Cellulose Nanocrystals from Different Lignocellulosic Residues to Chitosan/Glycerol Films

Polymers ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 658 ◽  
Author(s):  
de Andrade ◽  
Nery ◽  
de Santana e Santana ◽  
Leal ◽  
Rodrigues ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Moisture Content ◽  
Natural Resources ◽  
Wheat Bran ◽  
Diameter Ratio ◽  
Coconut Shell ◽  
Biodegradable Films ◽  
Lignocellulosic Residues ◽  
Corn Husk

Interest in nanocellulose obtained from natural resources has grown, mainly due to the characteristics that these materials provide when incorporated in biodegradable films as an alternative for the improvement of the properties of nanocomposites. The main purpose of this work was to investigate the effect of the incorporation of nanocellulose obtained from different fibers (corncob, corn husk, coconut shell, and wheat bran) into the chitosan/glycerol films. The nanocellulose were obtained through acid hydrolysis. The properties of the different nanobiocomposites were comparatively evaluated, including their barrier and mechanical properties. The nanocrystals obtained for coconut shell (CS), corn husk (CH), and corncob (CC) presented a length / diameter ratio of 40.18, 40.86, and 32.19, respectively. Wheat bran (WB) was not considered an interesting source of nanocrystals, which may be justified due to the low percentage of cellulose. Significant differences were observed in the properties of the films studied. The water activity varied from 0.601 (WB Film) to 0.658 (CH Film) and the moisture content from 15.13 (CS Film) to 20.86 (WB Film). The highest values for tensile strength were presented for CC (11.43 MPa) and CS (11.38 MPa) films, and this propriety was significantly increased by nanocellulose addition. The results showed that the source of the nanocrystal determined the properties of the chitosan/glycerol films.

Forced Convective Drying of a Porous Cube: Non-Intrusive Temperature and Mass Transfer Measurements

2014 ◽  
Author(s):  
Eoin Fanning ◽  
Tim Persoons ◽  
Darina B. Murray
Keyword(s):  
Mass Transfer ◽  
Temperature Distribution ◽  
Moisture Content ◽  
Surface Temperature ◽  
Convective Drying ◽  
Drying Rate ◽  
Local Surface ◽  
Number Range ◽  
Rate Period ◽  
Local Surface Temperature

The evolution of the mass transfer rate and temperature of a porous body in a convective drying process shows two main stages: A constant-drying rate period and a falling-drying rate period. This study investigates the simultaneous time evolution of moisture content and local surface temperature of a porous cube inside a rectangular flow channel for a range of air flow temperatures and Reynolds numbers. The moisture content is measured using a precision mass balance. Local surface temperature distribution is measured using a thermal imaging camera. In the constant-drying rate period, an average Nusselt number in the range 7.1 ≤ Nu ≤ 13.3 and an average Sherwood number of 4.7 ≤ Sh ≤ 6.0 are calculated for a Reynolds number range of 180 ≤ Re ≤ 595. Infrared thermography shows that the falling-drying rate period begins, the temperature distribution becomes non-uniform and approaches the temperature of the surroundings. This transition occurs first near the edges of the cube and, in particular, near the leading edge of the cube, as witnessed in previous studies.

scholarly journals Evaluation of a Moisture Diffusion Model for Analyzing the Convective Drying Kinetics of Lavandula x allardii Leaves

Computation ◽  
2021 ◽  
Vol 9 (12) ◽  
pp. 141
Author(s):  
Vasileios Chasiotis ◽  
Dimitrios Tzempelikos ◽  
Andronikos Filios
Keyword(s):  
Diffusion Model ◽  
Moisture Transfer ◽  
Variable Temperature ◽  
Moisture Diffusion ◽  
Drying Kinetics ◽  
Convective Drying ◽  
Water Evaporation ◽  
Drying Rate ◽  
Computationally Efficient ◽  
Kinetics Of

In the present case study, a moisture diffusion model is developed to simulate the drying kinetics of Lavandula x allardii leaves for non-stationary convective drying regimes. Increasing temperature profiles are applied over the drying duration and the influence of temperature advancing rates on the moisture removal and the drying rate is investigated. The model assumes a one-dimensional moisture transfer under transient conditions, which occurs from the leaf center to the surface by liquid diffusion due to the concentration gradient developed by the surface water evaporation caused by the difference of water vapor partial pressure between the drying medium and the leaf surface. A numerical solution of Fick’s 2nd law is obtained by an in-house code using the finite volume method, including shrinkage and a variable temperature-dependent effective moisture diffusion coefficient. The numerical results have been validated against experimental data for selected cases using statistical indices and the predicted dehydration curves presented a good agreement for the higher temperature advancing rates. The examined modeling approach was found stable and can output, in a computationally efficient way, the temporal changes of moisture and drying rate. Thus, the present model could be used for engineering applications involving the design, optimization and development of drying equipment and drying schedules for the examined type of non-stationary drying patterns.

scholarly journals EFFECT OF PLASTICIZERS ON MECHANICAL PROPERTIES OF EDIBLE FILM FROM JANENG STARCH – CHITOSAN

2016 ◽  
Vol 16 (2) ◽  
pp. 45-49
Author(s):  
Narlis Juandi ◽  
Rahmi Rahmi ◽  
Hira Helwati
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Palm Oil ◽  
Edible Films ◽  
Ftir Spectra ◽  
Edible Film ◽  
Biodegradable Films ◽  
Elongation At Break

The interest in the development of edible and biodegradable films has increased because it is every day more evident that non degradable are doing much damage to the environment. In this research, edible films were based on blends of janeng starch in different proportions, added of palm oil or glycerol, which were used as plasticizers. The objective was to study the effect of two different plasticizers, palm oil and glycerol of edible film from janeng starch–chitosan on the mechanical properties and FTIR spectra. Increasing concentration of glycerol as plasticizer resulted tend to increased tensile strength and elongation at break. The tensile strength and elongation at break values for palm oil is higher than glycerol as plasticizer at the same concentration. FTIR spectra show the process of making edible film from janeng starch–chitosan with palm oil or glycerol as plasticizers are physically mixing in the presence of hydrogen interactions between chains.

Study of the Drying Rate and Colour Kinetics during Stepwise Air-Drying of Apricot Halves

2019 ◽  
Vol 15 (5-6) ◽  
Author(s):  
G. Xanthopoulos ◽  
A. Athanasiou ◽  
A. Sempou ◽  
D. Lentzou ◽  
Ch. Templalexis ◽  
...  
Keyword(s):  
Temperature Profile ◽  
Drying Rate ◽  
Temperature Profiles ◽  
Air Drying ◽  
Browning Index ◽  
Colour Kinetics ◽  
Levenberg Marquardt ◽  
Rate Period ◽  
Step Down ◽  
Kinetics Of

AbstractThe drying rate and colour kinetics of apricot halves were studied during stepwise air-drying compared to continuous drying. The tested stepwise temperature profiles exhibited two successive falling rate periods, which differed from the drying rate period of the constant drying temperature profile. Three chromatic indices, namely browning index, chroma and hue were analysed. The analysis showed that treatment with ascorbic acid was more effective during the step up temperature profile, whilst its antioxidant activity was lost during the step down temperature profile due to the initially used high drying temperatures. The chromatic indices were described by a modified kinetic model, the parameters of which were estimated by the Levenberg–Marquardt optimization algorithm and in all cases was derived R2adj≥ 0.88 and MRD < 4.88%.

Mechanical Properties of Methylcellulose-Based Films Containing Stearic Acids

2013 ◽  
Vol 666 ◽  
pp. 23-26
Author(s):  
Tian Zhong ◽  
Zi Xuan Lian ◽  
Zhe Wang ◽  
Yan Qing Niu ◽  
Zhong Su Ma
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Elastic Modulus ◽  
Polyethylene Glycol ◽  
Dry Matter ◽  
Smooth Curve ◽  
Polyethylene Glycol 400 ◽  
Peg 400 ◽  
Film Forming ◽  
Homogenization Methods

The effect of the homogenization conditions of the film-forming emulsions on the mechanical properties of Methylcellulose (MC)-based films containing stearic acids (SA) was studied. For this purpose, the initial emulsions were prepared in different dry matter ratios and treated by different homogenization methods. The mechanical properties, including elastic modulus (EM), tensile strength (TS) and elongation (E) became worse with the increase of the SA content. Then the mechanical properties were compared as a function of the polyethylene glycol 400 (PEG-400) contents. As a plasticizer, the increasing of PEG-400 could improved E greatly, but EM and TS both declined slightly. And finally, when homogenization conditions were more intense, EM and TS increased significantly while E showed a fairly smooth curve.

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