Physicochemical, structural, and rheological characteristics of corn starch after thermal-ultrasound processing

Thermal-ultrasound treatment is a green technology that can significantly alter the structural and functional properties of starches. This research extend the effect of at different temperatures (25 °C, 45 °C, and 65 °C) and times (30 and 60 min) on the physicochemical, structural, and rheological properties of corn starch was studied. Amylose content, solubility, swelling power, and the least gelling content increased with increasing temperature and time. Starch treated at 45 °C for 30 min had the lowest syneresis among all treatments. Thermal-ultrasound treatment at 25 °C and 65 °C for 60 min caused increasing paste clarity. Microscopic observations demonstrated that the starch granules were agglomerated at 65 °C. Although the crystallinity of samples decreased from 35.42% to 8.94%, the storage modulus was more than the loss modulus during the frequency sweep test. Pasting properties showed that pasting temperatures shifted to higher values after treatment. Nonetheless, the maximum viscosity decreased, and the final viscosity of the treated samples demonstrated that short-term retrogradation could deteriorate. Results showed that thermal-ultrasound is a viable technique for starch modification compared to conventional thermal and ultrasound treatments.

Study on Vibration Reduction Due to Pile-Raft Foundation for High-Tech Lab Based on Frequency Sweep Test

Evaluation of the vibration reduction of piled-slab is of great significance for the layout of process and power equipment in high-tech facilities. In-situ measurement was performed to study the vibration reduction of the piled-slab of a high-tech lab. Slab vibrations with frequencies of 10 Hz to 60 Hz with steps 5 Hz were induced by an electromagnetic vibration exciter. INV3062U data acquisition device and 941B sensor were used to measure the velocities in the vertical direction at six measurement locations on the slab surface. For single frequency, the measurement results showed that the peak values of the slab vibration velocities generally decayed nonlinearly as the distance increased, however, the attenuations of 25 Hz, 35 Hz, 40 Hz, 50 Hz and 60 Hz slab vibrations were not monotonically.

The Effect of pH and Concentration on the Textural and Rheological Properties of Egg Albumin Foams

The effect of different concentrations (i.e. 0.1% - 1%) and pH (7.0 and 4.0) on the textural/physical and rheological properties of egg albumin foams was investigated. The findings indicated that the stability and overrun of the foams were higher in the case of the foams made at pH = 4.0 and with the highest concentration of egg albumin (1%). The apparent viscosity of the albumin solution was significantly (p<0.05) higher at pH = 4.0 and in the presence of the higher concentrations of egg albumin (0.5% - 1%). All of the rheological parameters in amplitude sweep test indicated a weak structure of the foam made at pH = 7.0 and in the presence of a low concentration of egg albumin (0.1%). Regardless of the pH, the values for tan (δ) in the frequency sweep test indicated a weak biopolymer foam structure in the case of all samples. Yield stress was greater in the sample manufactured at pH = 4.0. Overall, the findings suggested that both protein concentration and pH had substantial effects on the rheological and physical properties of egg albumin foams.

Performance Evaluation of Anti-Ultraviolet Ageing Bitumen with Combined Modification Based on Dynamic Rheological Test

Based on the rheological property master curve, a new definition of ageing index was proposed for styrene-butadiene-styrene block copolymer (SBS) modified bitumen. The UV ageing resistance of the combined-modifier modified SBS bitumen was evaluated. Twelve different methods of combined modification were designed with three kinds of modifiers: ultraviolet absorber (Tinuvin 770), organic montmorillonite (OMMT) and layered double hydroxide (LDHs). With modified SBS bitumen, short-term ageing (TFOT) and laboratory ultraviolet ageing (UV) were performed. The dynamic shear rheometer (DSR) was used to perform frequency sweep test on the samples before and after ageing. The rheological property master curve was obtained by fitting the constitutive model equation. Based on the rheological property master curve, a new definition ageing index was proposed for SBS bitumen to evaluate the modified bitumen with different combined-modifier. The results show that the ageing index could effectively evaluate the UV ageing resistance of SBS bitumen. The evaluation results show that the combined-modifier bitumen exhibits better anti-ultraviolet ageing effects than a single modifier. Among them, the combined-modifier modes of 0.3%Tinuvin770+5%OMMT and 0.6%Tinuvin770+2.5%LDHs performed.

Rheological Properties and Application of Molasses Modified Bitumen in Hot Mix Asphalt (HMA)

The use of molasses as a replacement for bitumen could benefit the pavement industry by improving the performance of the pavement or by lowering its cost. An experimental investigation was carried out to investigate the effect of molasses with different moisture contents on the property of hot-mix asphalt (HMA). Bitumen binders (BB) containing 5%, 10%, 15%, and 20% molasses were investigated as molasses modified binders (MMB). Molasses with 24.9% and 5.02% by weight of water were used to investigate the effect of moisture on the MMBs. In addition to the conventional binder tests, additional tests such as the Fourier transform infrared (FTIR) test, amplitude and frequency sweep test, performance grade (PG) test, and multiple stress creep recovery (MSCR) test were performed. The results indicated that most of the properties of the MMBs improved with the reduction in the moisture content of molasses but worsened with the percentage replacement of molasses. The IR spectra show that the carbonyl index decreased with an increasing amount of molasses. The control grade PG58 was improved to PG64 and PG70 when the base binder was modified with molasses and aged with rolling thin film oven (RTFO) consecutively. At a temperature of 58 °C, non-recoverable creep compliance of 3.2 kPa (Jnr3.2kPa) was decreased for each MMB, which leads to improved rutting potential. At a temperature of 64 °C, the Jnr value was decreased only for the MMB containing 5% molasses, and then gradually increased for the remaining MMBs. Generally, the study revealed that low moisture content molasses could be used as a partial replacement for bitumen to enhance the rheological properties of the bitumen.

Rheological and Resistance Properties of Magnetorheological Elastomer with Cobalt for Sensor Application

Cobalt particles have been introduced as a filler due to the advantages of embedding their magnetic and electrical properties in magnetorheological elastomer (MRE). In the present research, the rheology and resistance of MRE are experimentally evaluated. Isotropic and anisotropic MRE samples containing silicone rubber and cobalt particles were fabricated. The magnetic properties of MRE are conducted using a vibrating sample magnetometer (VSM). The morphological aspects of MRE are observed by using field emission scanning electron microscopy (FESEM) and characterized by energy-dispersive X-ray spectroscopy (EDX). Rheological properties under various magnetic field strengths were measured for the magnetic field, strain amplitude, and frequency sweep test by using a parallel-plate rheometer. Subsequently, the resistance of MRE is tested under different applied forces and magnetic fields. The MRE storage modulus depicted an enhancement in field-dependent modulus across all the applied magnetic fields. The electrical resistance generated from the sample can be manipulated by external magnetic fields and mechanical loads. The conductivity of MRE is due to the existence of cobalt arrangements observed by FESEM. By introducing cobalt as filler and obtaining satisfactory results, the study might open new avenues for cobalt to be used as filler in MRE fabrication for future sensing applications.

Design and Analysis of a Magnetically Coupled Multi-Frequency Hybrid Energy Harvester

The approach to improve the output power of piezoelectric energy harvester is one of the current research hotspots. In the case where some sources have two or more discrete vibration frequencies, this paper proposed three types of magnetically coupled multi-frequency hybrid energy harvesters (MHEHs) to capture vibration energy composed of two discrete frequencies. Electromechanical coupling models were established to analyze the magnetic forces, and to evaluate the power generation characteristics, which were verified by the experimental test. The optimal structure was selected through the comparison. With 2 m/s2 excitation acceleration, the optimal peak output power was 2.96 mW at 23.6 Hz and 4.76 mW at 32.8 Hz, respectively. The superiority of hybrid energy harvesting mechanism was demonstrated. The influences of initial center-to-center distances between two magnets and length of cantilever beam on output power were also studied. At last, the frequency sweep test was conducted. Both theoretical and experimental analyses indicated that the proposed MHEH produced more electric power over a larger operating bandwidth.

Evaluation of the Rheological Property of Binder-Filler Systems after Oxidation Based on a Simple Film Oven Aging Method

Asphalt mastic is a combination of binder and filler. The binder-filler system within asphalt mixtures plays an important role in adhesion between mineral aggregates. The aging of binders in pavement always happens with fillers inside or contact with mineral aggregates, so it is critical to investigate the evolved rheological property of binder-filler systems during oxidative aging. In this study, simple film oven aging methods for the aging of mastics (binder-filler system) were conducted and verified by comparing the master-curves of aged mastics at different oven positions or different aging times. The frequency sweep test was performed to measure the changing stiffness of mastics with a different combination of binders and filler contents. Test results show that oven positions could influence the aging effect of the mastics significantly, given the influence of circulation. With increasing aging times, the complex modulus increases while phase angle decreases. Comparing the mastics which were first aged then mixed with mastics which were first mixed then aged, it was observed that fillers inside the binder could accelerate aging of the mastics. Additionally, the aging index of mastics with different combinations showed that both the modification of binders and filler contents could affect the aging rate of the mastics.

Influence of Chemical Constituents of Asphalt Binders on Their Rheological Properties

The goal of this study is to investigate the chemical constituents and rheological properties of three different binders used in the State of Qatar. Binders were designated as WL (source 1, low density), WH (source 1, high density) and AH (source 2, high density). Binder composition analysis was carried out using the saturates, aromatics, resins and asphaltene determinator (SAR-AD) technique. The percentages of saturates, aromatics, resins and asphaltenes were measured, and from those, the total pericondensed aromatics (TPA), absorbance aging index (AAI), and colloidal instability index (CII) were obtained and their relationship to rheological test results was investigated. In the rheological investigation, the linear viscoelastic properties of these binders were evaluated using a frequency sweep test. The rutting characteristics were evaluated using the percentage of recovery and non-recoverable creep compliance values from the multiple stress creep and recovery (MSCR) test, while the fatigue resistance was assessed using the linear amplitude sweep (LAS) test. The WL binder was found to have the highest stiffness, which is associated with the highest TPA content. From the MSCR test, the AH binder had the lowest rut resistance. This binder also had the lowest CII value, which represents the balanced chemical composition of this material. Out of the three binders, WH had the highest AAI value which is related to the least fatigue life as measured in the LAS test.