scholarly journals Comparison of Rheological Behaviour of Bio-Based and Synthetic Epoxy Resins for Making Ecocomposites

Fluids ◽  
2021 ◽  
Vol 6 (1) ◽  
pp. 38
Author(s):  
Samireh Vahid ◽  
Valentino Burattini ◽  
Saeed Afshinjavid ◽  
Arash Dashtkar
Keyword(s):  
Phase Angle ◽  
Epoxy Resins ◽  
Loss Modulus ◽  
Rheological Behaviour ◽  
General Tendency ◽  
Test Results ◽  
High Frequencies ◽  
Oscillatory Rheology ◽  
Linear Viscoelastic ◽  
Typical Behaviour

In this paper, the rheological behaviour of a petroleum-based epoxy (EL2 laminating epoxy) was compared with the Super Sap CLR clear bio-resin epoxy. The focus of the work was on the viscous and viscoelastic performance of these epoxy resins. Rheological tests were carried out at 15, 30, and 60 min after the mixing of the pure epoxies and the hardeners at a constant temperature of 25 °C. The results obtained from the rheometer tests showed that the viscosity of both epoxy systems decreased with increasing shear rate, which is typical behaviour of a shear thinning fluid. Regarding the oscillatory rheology tests, the viscoelastic properties of both epoxy resins were studied within their linear viscoelastic region (LVER) by amplitude sweep test, which was also carried out 15, 30, and 60 min after mixing the epoxies with the hardeners. It was noticed that the petroleum-based epoxy possessed a more significant LVER relative to the bio-based resin. Finally, the storage modulus (G′), the loss modulus (G″), and the phase angle were extracted, and these parameters were investigated over low and high frequencies. From the test results, we observed that both epoxy resins showed a liquid-like viscoelastic behaviour due to their phase angle values, which were always between 45° and 90°, and by the general tendency of the G″ predominance over G′ at low and high frequencies.

Modified Bilston Nonlinear Viscoelastic Model for Finite Element Head Injury Studies

2006 ◽  
Vol 128 (5) ◽  
pp. 797-801 ◽  
Author(s):  
F. Shen ◽  
T. E. Tay ◽  
J. Z. Li ◽  
S. Nigen ◽  
P. V. S. Lee ◽  
...  
Keyword(s):  
Finite Element ◽  
Head Injury ◽  
Brain Tissue ◽  
Loss Modulus ◽  
Viscoelastic Model ◽  
Constitutive Law ◽  
Critical Parameters ◽  
Test Results ◽  
High Frequencies ◽  
Nonlinear Viscoelastic

This paper proposes a modified nonlinear viscoelastic Bilston model (Bilston et al., 2001, Biorheol., 38, pp. 335–345). for the modeling of brain tissue constitutive properties. The modified model can be readily implemented in a commercial explicit finite element (FE) code, PamCrash. Critical parameters of the model have been determined through a series of rheological tests on porcine brain tissue samples and the time-temperature superposition (TTS) principle has been used to extend the frequency to a high region. Simulations by using PamCrash are compared with the test results. Through the use of the TTS principle, the mechanical and rheological behavior at high frequencies up to 104rad∕s may be obtained. This is important because the properties of the brain tissue at high frequencies and impact rates are especially relevant to studies of traumatic head injury. The averaged dynamic modulus ranges from 130Pato1500Pa and loss modulus ranges from 35Pato800Pa in the frequency regime studied (0.01rad∕sto3700rad∕s). The errors between theoretical predictions and averaged relaxation test results are within 20% for strains up to 20%. The FEM simulation results are in good agreement with experimental results. The proposed model will be especially useful for application to FE analysis of the head under impact loads. More realistic analysis of head injury can be carried out by incorporating the nonlinear viscoelastic constitutive law for brain tissue into a commercial FE code.

scholarly journals Rheological properties and flow behaviour of wax-stabilized water-in-oil emulsions

2021 ◽  
Author(s):  
Samira Haj-Shafiei
Keyword(s):  
Rheological Properties ◽  
Initial Temperature ◽  
Rheological Behaviour ◽  
Flow Behaviour ◽  
Paraffin Wax ◽  
Oscillatory Rheology ◽  
Initial Deposition ◽  
Oil Emulsions ◽  
Light Mineral ◽  
Glycerol Monooleate

The objective of this study was to characterize the flow and rheological behaviour of model wax-stabilized water-in-oil (W/O) emulsions consisting of light mineral oil, paraffin wax and glycerol monooleate as the oil phase and water as the dispersed aqueous phase. An[sic] laboratory-scale benchtop flowloop system was used to explore the flow behaviour of the emulsions' oil phase (oil, paraffin wax and surfactant). The key contribution from this work was that the higher initial temperature gradient (40°C compared to 19°C) experienced by the rapidly-cooled oil led to more initial deposition on the flowloop inner wall. The rheological properties of W/O emulsions with different water cuts (10-50wt%) were also studied. Rotational, oscillatory rheology and creep compliance and recovery were characterized on emulsions aged up to 28 days. Overall, the results demonstrated that emulsion composition, and age could significantly influence an emulsion's flow behaviour and rheological properties.

scholarly journals Rheological properties and flow behaviour of wax-stabilized water-in-oil emulsions

2021 ◽  
Author(s):  
Samira Haj-Shafiei
Keyword(s):  
Rheological Properties ◽  
Initial Temperature ◽  
Rheological Behaviour ◽  
Flow Behaviour ◽  
Paraffin Wax ◽  
Oscillatory Rheology ◽  
Initial Deposition ◽  
Oil Emulsions ◽  
Light Mineral ◽  
Glycerol Monooleate

The objective of this study was to characterize the flow and rheological behaviour of model wax-stabilized water-in-oil (W/O) emulsions consisting of light mineral oil, paraffin wax and glycerol monooleate as the oil phase and water as the dispersed aqueous phase. An[sic] laboratory-scale benchtop flowloop system was used to explore the flow behaviour of the emulsions' oil phase (oil, paraffin wax and surfactant). The key contribution from this work was that the higher initial temperature gradient (40°C compared to 19°C) experienced by the rapidly-cooled oil led to more initial deposition on the flowloop inner wall. The rheological properties of W/O emulsions with different water cuts (10-50wt%) were also studied. Rotational, oscillatory rheology and creep compliance and recovery were characterized on emulsions aged up to 28 days. Overall, the results demonstrated that emulsion composition, and age could significantly influence an emulsion's flow behaviour and rheological properties.

Mask Image Planning for Deformation Control in Projection-Based Stereolithography Process

2012 ◽  
Author(s):  
Kai Xu ◽  
Yong Chen
Keyword(s):  
Epoxy Resins ◽  
Lower Cost ◽  
Shape Deformation ◽  
Future Research ◽  
Test Results ◽  
Digital Micromirror Device ◽  
Research Directions ◽  
Deformation Control ◽  
Size Accuracy ◽  
Future Research Directions

In this research, we investigate the shrinkage related deformation control for a mask-image-projection-based Stereolithography process (MIP-SL). Based on a Digital Micromirror Device (DMD), MIP-SL uses an area-processing approach by dynamically projecting mask images onto a resin surface to selectively cure liquid resin into layers of an object. Consequently, the related additive manufacturing process can be much faster with a lower cost than the laser-based Stereolithography Apparatus (SLA) process. However, current commercially available MIP-SL systems are based on Acrylate resins, which have bigger shrinkages than epoxy resins that are widely used in the SLA process. Consequently controlling size accuracy and shape deformation in the MIP-SL process is challenging. To address the problem, we evaluate different image exposing strategies for projection mask images. A mask image planning method and related algorithms have been developed for the MIP-SL process. The planned mask images have been tested by using a commercial MIP-SL machine. The experimental results illustrate that our method can effectively reduce the deformation by as much as 32%. A discussion on the test results and future research directions are also presented.

SYNTHESIS AND VISCOELASTIC BEHAVIORS OF POLY(ANILINE-CO-O-ETHOXYANILINE) PARTICLES SUSPENDED ELECTRORHEOLOGICAL FLUID

2001 ◽  
Vol 15 (06n07) ◽  
pp. 649-656 ◽  
Author(s):  
H. J. CHOI ◽  
J. W. KIM ◽  
M. S. SUH ◽  
M. J. SHIN ◽  
K. TO
Keyword(s):  
Particle Size ◽  
Silicone Oil ◽  
Loss Modulus ◽  
Chemical Oxidation ◽  
Steady Shear ◽  
Rheological Parameters ◽  
Linear Viscoelastic Region ◽  
Linear Viscoelastic ◽  
Er Fluids ◽  
Poly Aniline

Copolyanilines are synthesized by a chemical oxidation of aniline and o-ethoxyaniline with various molar ratios in an acidic media, and then characteristics of these polymers such as chemical structure, particle size and the particle size distribution were examined by using FT-IR, SEM and particle size analyzer, respectively. Suspensions of copolyaniline containing ethoxy group, namely poly(aniline-co-o-ethoxyaniline), in silicone oil have been investigated as one of many potential candidates for dry-base electrorheological (ER) fluid systems. Rotational rheometer (Physica) equipped with a high voltage generator was used to characterize the rheological properties of ER fluids from both steady shear and dynamic tests. From the steady shear experiment, we obtained flow properties and found that ER fluids exhibited the yield phenomenon. On the other hand, viscoelastic property was also obtained from the dynamic experiment. Since viscoelastic properties for ER fluids are mainly dominated by the particle chain structure, the state at different time scale was analyzed from the rheological parameters such as storage modulus (G'), loss modulus (G'') and tan δ. We conducted a strain amplitude sweep at 1 Hz under an applied electric field to determine a linear viscoelastic region first. The G' and G'' were then measured by a frequency sweep from 0.1 to 100 Hz in the linear viscoelastic region.

Thermo-Mechanical Analysis of Chosen Epoxy Resins Used in Aviation Technology

2015 ◽  
Vol 1126 ◽  
pp. 187-193
Author(s):  
Kamil Prusak ◽  
Janusz Zmywaczyk ◽  
Piotr Koniorczyk ◽  
Jan Godzimirski ◽  
Marcin Cegła
Keyword(s):  
Thermal Expansion ◽  
Epoxy Resins ◽  
Loss Modulus ◽  
Testing Machine ◽  
Mechanical Analysis ◽  
Stress Strain ◽  
Temperature Range ◽  
Heating And Cooling ◽  
Tan Δ ◽  
Material Testing Machine

In this paper the results of storage modulus (E’), loss modulus (E’’) and damping parameter tan (δ)=E''/E' of epoxy resins Epidian 57 and L285 with curing agents Z1 and LH285, respectively are presented. In addition to this the stress-strain and thermal expansion characteristics of Epidian 53, 57 and L285 were obtained experimentally in order to compare Dynamic Mechanical Analysis (DMA) results. Temperature range of DMA investigations using Netzsch (Germany) DMA 242C analyzer was from-120 °C to +110 °C at the heating rate of 1 K/min with frequency of {0.1, 1, 10} Hz, respectively. Netzsch DIL 402C dilatometer was used to study the thermal expansion of the tested samples within temperature range from 30 °C to 80 °C at 1 K/min of heating and cooling rates, respectively and Huang TA computer servo control material testing machine HT-2402 was applied to determine the stress-strain characteristics. Measurements of sample elongation ΔL and physical α* were performed twice in heating and cooling cycles. The glass transition temperature Tg determined from maximum of tan (δ) curve at f = 1Hz was equal to 76.7 °C for E57 and 87.2 °C for L285. It has been observed durable deformed shape of L285 sample with deflection in the middle about 5 mm just after finishing the DMA first run of heating which significantly affected DMA results during the second run of heating

Rheology of Barium Sulfate Suspensions and Pre-thickened Beverages Used in Diagnosis and Treatment of Dysphagia

2007 ◽  
Vol 17 (3) ◽  
pp. 33137-1-33137-8 ◽  
Author(s):  
Mustapha M. Ould Eleya ◽  
Sundaram Gunasekaran
Keyword(s):  
Barium Sulfate ◽  
Loss Modulus ◽  
Diagnosis And Treatment ◽  
Creep Recovery ◽  
Frequency Spectra ◽  
Fluid Foods ◽  
Linear Viscoelastic ◽  
Dysphagic Patients ◽  
Treatment And Diagnosis ◽  
Barium Sulfate Suspension

Abstract Pre-thickened beverages and barium sulfate suspensions are used in the treatment and diagnosis of dysphagia. These liquids are labeled nectar consistency (NC), honey consistency (HC) etc. These labels are rather misleading and do not represent the actual rheological character of the liquids. We carefully investigated the rheology of these liquids to assist both in their formulation and use for dysphagic patients. Steady state flow properties, thixotropy, dynamic response, and creep recovery behavior were investigated for six beverages and two barium sulfate suspensions. All samples exhibited a shear-thinning behavior. The flow curves of all samples followed both Herschel-Bulkley and Casson models. HC barium sulfate suspension exhibited higher yield stress, σo, and higher storage modulus, G’, than their fluid food counterparts. In contrast, NC barium sulfate suspension had lower σo, and G’ than some of the liquid food counterparts. Frequency spectra of NC samples were similar to that of a macromolecular solution with both G’ and loss modulus, G’’, increasing with frequency; whereas those of HC samples were similar to that of a gel with a little dependency of G’ and G’’ over frequency. Stress sweep experiments showed that the linear viscoelastic region of fluid foods and barium sulfate suspensions extended up to 1 and 10 Pa, respectively. Thus, significant differences exist in the rheological properties of both pre-thickened and videofluoroscopy fluids currently used for diagnosis and treatment of dysphagia.

Preparation and physical characterization of strongly swellable oligo(oxyethylene) lignin hydrogels

Holzforschung ◽  
2011 ◽  
Vol 65 (3) ◽  
Author(s):  
Lars Passauer ◽  
Klaus Fischer ◽  
Falk Liebner
Keyword(s):  
Dynamic Viscosity ◽  
Loss Modulus ◽  
Gelation Time ◽  
Rheological Behaviour ◽  
Diglycidyl Ether ◽  
Cross Linking ◽  
Available Water Content ◽  
The Cross ◽  
Poly Ethylene ◽  
Tan Δ

Abstract Highly swellable, mechanically stable hydrogels were obtained by cross-linking different technical lignins with poly(ethylene) glycol diglycidyl ether (PEGDGE). The gelation time and the properties of the products can be controlled by the extent of pre-oxidation and the cross-linking conditions, namely the dynamic viscosity η*, storage and loss modulus (G′; G″), and loss factor tan δ. The highest free swelling capacities (FSC) of up to 50 g water per g xerogel were obtained from pre-oxidized pine kraft lignin Indulin® AT and spruce organosolv lignin. Dynamic rheological measurements confirmed the typical rheological behaviour of gel structures, i.e. a linear decrease of dynamic viscosity about three orders of magnitude within a frequency range of 0.08 and 20 s-1. The results furthermore revealed a good mechanical sturdiness of the cross-linked lignin hydrogels. Sandy soils supplemented with small quantities of the hydrogels were found to feature a significantly increased plant-available water content. Based on the observed effects, oligo(oxyethylene) lignins are promising materials with respect to a prolonged water retention in soils.

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