Characterization of viscoelastic properties of minced beef meat thawed by ohmic and conventional methods

Frozen minced meat samples having fat contents of 2%, 10% and 18% were thawed using different methods (refrigeration thawing at ambient temperature of +4 ℃, under running cold water (+4 ℃) thawing, ohmic thawing for 10, 13 and 16 V/cm). Viscoelastic properties were determined by using rheological tests (oscillation and creep/recovery tests). Storage modulus, loss modulus, complex modulus, loss tangent, dynamic viscosity and complex viscosity values of minced meat samples increased as fat content increased. As frequency value increased, the modulus values of meat samples increased but dynamic and complex viscosity values of the samples decreased. The minced meat samples thawed by different methods had recoverable compliance values. The compliance values of meat samples during creep region can be well characterized by Burgers model. Ohmic thawing can be used as an alternative thawing method since it resulted in similar rheological properties of minced meat samples compared to refrigeration thawing at ambient temperature of +4 ℃ and under running cold water (+4℃) thawing.

Characterization of neat and modified asphalt binders and mixtures in relation to permanent deformation

The addition of polymers on asphalt binders aims to enhance their performance, especially at high temperatures, which correspond to rutting resistance. The Superpave rutting parameter (|G*|/sinδ) has been considered to be inadequate to characterize the performance of modified materials, therefore the Multiple Stress Creep and Recovery (MSCR) test was developed, providing the parameter non-recoverable compliance (Jnr). This research has the main objective of correlating asphalt binders performance-based characterization with rutting resistance of asphalt mixtures, and presents results obtained for one conventional (50/70 penetration grade) and two modified asphalt binders (2.1% RET and 1.9% RET) regarding their rheological characteristics. With the use of the dynamic shear rheometer (DSR), master curves and MSCR results were obtained for the three binders. In addition, permanent deformation tests were performed on the asphalt mixtures by means of laboratory traffic simulation. The rutting characterization indicated higher permanent deformation resistance for the modified binders for the asphalt binder and the asphalt mixture testing. The main conclusions were that the use of modified binder reduced in approximately 50% the Jnr values and the rut depth; also, the asphalt binders’ characteristics were able to predict the asphalt mixtures rutting resistance.

Influence of processing parameters on creep and recovery behavior of FDM manufactured part using definitive screening design and ANN

Purpose The purpose of this paper is to investigate the effect of process parameters of fused deposition modelling (FDM) 3D printing process on viscoelastic responses (creep compliance and recoverable compliance) of FDM built parts using a novel experimental design technique. Design/methodology/approach As part of the process characterization, a recently developed class of three-level design methodology – definitive screening design (DSD) – was used in this study to fit a second-order polynomial regression model. Artificial neural network (ANN) was also used to determine the optimal process parameters to improve creep compliance and recoverable compliance. The relationship between layer thickness, air gap, raster angle, build orientation, road width, number of contours and creep performance of FDM fabricated part was thereafter established empirically. Scanning electron microscope (SEM) is used to examine and characterize the morphology of the structures for some samples. Findings This study found that the creep resistance of FDM-manufactured part is significantly influenced by layer thickness, air gap, raster angle and number of contours and it can be improved by optimizing the settings of the selected parameters. The relationship between FDM process parameters and creep properties was determined, with the best creep performance observed by using 0.127 mm of layer thickness, zero air gap, zero raster angle, build orientation of 17.188°, road width of 0.4572 mm and 10 contours. Finally, the result is verified by confirmation experiments. The results prove that a DSD is a very effective design in characterizing the influence of process parameters on creep properties of FDM-built part at the lowest cost. Originality/value The originality of this paper lies in characterizing and optimizing the effect of process parameters on creep performance of FDM manufactured part that has not been studied in all previous studies. The paper highlights, for the first time, how the application of DSD can overcome most of the limitations encountered in the conventional techniques. This study can be used as a guide to the different additive manufacturing users of various industries and the results provide a good technical database on how FDM process parameters influence the creep performance of manufactured parts.

Using Modified Creep and Recovery Tests to Evaluate the Foam-Based Warm Mix Asphalt Contained Nano Hydrated Lime

Two Nano Hydrated Lime (NHL) materials with particle sizes of 50 nm and 100 nm were used in this study to investigate to the effect of NHL modification on the creep and recovery of Warm Mix Asphalt (WMA) binders foamed using Advera® with respective to rutting. The NHL was added to the asphalt binder at ratios of 20%, 10%, and 5% by weight of the asphalt binder. The creep and recovery tests were performed at three different stress levels, 3Pa (creep for 100 sec. and 600 sec. recovery), 10Pa (creep for 20 sec. and 600 sec. recovery), and 50Pa (creep for 1 sec and 300 sec. recovery). The tests were performed at a temperature of 58oC. The results were also compared with the Regular Hydrated Lime (RHL) results. The overall results reveal that the neat asphalt binders foamed using advera® showed larger permanent deformation (rutting) potential compared to the binder modified with RHL and NHL foamed using Advera®. As the NHL dose increases, the non-recoverable compliance decreases (rutting decreases). It was also concluded that the application of the RHL with the normal dose (20% by weight of binder) can be replaced by adding 5% (by weight of binder) of 50 nm NHL with respective to rutting.

Correlation between permanent deformation-related performance parameters of asphalt concrete mixes and binders

This paper examines methods to predict the performance of hot asphalt concrete mixes based on performance parameters of binders. Specifically, relationships between binder parameters determined from multiple stress creep and recovery tests were correlated to the creep parameters of hot asphalt concrete mixes obtained from cyclic load compression testing. For the determination of creep parameters, a modified expression of the creep curve is proposed to cover the entire spectrum of permanent deformation; including the tertiary creep phase. Non-recoverable compliance, unrecovered strain, and recoverable strain of binders show good correlation to creep parameters of hot asphalt concrete mixes such as creep rate and high temperature performance ratio. Additionally, unrecovered strain and non-recoverable compliance of binders correlates well with mean rut depth of asphalt concrete mixes. However, no correlation has been detected between the difference in non-recoverable compliance of binders and permanent deformation parameters of asphalt concrete mixes.

Recovery of Shear-Modified Polybutadiene Solutions

We have investigated the recovery of the overshoot in the transient viscosity, the first normal stress coefficient, and the dynamic modulus for entangled polybutadiene solutions subjected to nonlinear shear flow. The molecular-weight dependences of the various time scales (linear viscoelastic relaxation time, entanglement recovery time, and timescale for decay of stress following cessation of shearing) are all consistent with the usual 3.4 power law. Nevertheless, the time for recovery of the stress overshoot and plateau value of the dynamic modulus were substantially longer (by as much as two orders of magnitude) than the linear viscoelastic relaxation time calculated from the Newtonian viscosity and the equilibrium recoverable compliance. These results indicate that complete entanglement recovery requires cooperative chain motions over a length scale exceeding that associated with linear relaxation. This persistence of a disentangled state means that a state of low viscosity and reduced elasticity is retained for an extended time, suggesting that shear modification can be used to facilitate the processing of polymers.

Rheology of Blends of a Rodlike Polymer (PBO) and its Flexible Chain Analog

ABSTRACTRheological properties of isotropic solutions of rodlike poly(p-phenylene benzbisoxazole), PBO, flexible chain poly(2,5-benzoxazole), ABPBO, and their miscible blends in solution are described. Measurements include steady state properties (the viscosity and recoverable compliance as functions of shear rate), transient properties (the recoverable compliance), and dynamic mechanical properties (the loss and storage compliances as functions of frequency). The relaxation spectrum of the blends is broader than that for the rodlike chain, and tends to occur at longer times, reflecting a viscosity enhancement that occurs with the blends. The measured zero shear viscosities for rod and blend solutions are compared with predictions based on the model of Doi and Edwards.