Loss modulus measurement of a viscoelastic polymer at acoustic and ultrasonic frequencies using vibrothermography

The objective of the present investigation is to develop and study the thermal and rheological properties of the in-house developed flexible abrasive media. It is a mixer of viscoelastic polymer and plasticizer mixed with micro-abrasive particles, used for removing debris and irregularities present on internal and external complex surfaces used in the aerospace, automotive and medical industries. This paper presents, morphology of the developed abrasive media is captured using the Scanning Electron Microscope (SEM), thermal properties of the abrasive media are studied using Thermo Gravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC) analysis along with tensile properties of the abrasive media ascertained using the universal testing machine. The rheological properties of the media play a major role in media flow over the intricate shapes and removing the material from the surface. To understand the media behavior, further rheological properties such as viscosity, shear stress, storage modulus, loss modulus, loss tangent, and complex viscosity are ascertained with varying shear rate and frequency at different temperature using rheometer. The TGA and DSC results shows abrasive media has good thermal stability and possibility of using the media for finishing process under lower temperature <100 °C. Rheological studies shows the shear thinning behaviour of the media and elastic solid behavior (G′ > G′′) at different temperatures which is suitable for finishing the complex internal and the external features efficiently and effectively. The developed abrasive media is used to finish the hydraulic components which are difficult to access with conventional tools and the results of finishing process are presented.

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Influence of κ-Carrageenan, Modified Starch and Inulin Addition on Rheological and Sensory Properties of Non-fat and Non-added Sugar Dairy Dessert

Current Nutrition & Food Science ◽

10.2174/1573401315666190301152645 ◽

2020 ◽

Vol 16 (4) ◽

pp. 462-469

Author(s):

Zhaleh Sheidaei ◽

Bahareh Sarmadi ◽

Seyede M. Hosseini ◽

Fardin Javanmardi ◽

Kianoush Khosravi-Darani ◽

...

Keyword(s):

Storage Modulus ◽

Loss Modulus ◽

Viscoelastic Behavior ◽

Textural Properties ◽

Complex Viscosity ◽

Sensory Properties ◽

Modified Starch ◽

Consumer Health ◽

Added Sugar ◽

Textural Parameters

Background: The high amounts of fat, sugar and calorie existing in dairy desserts can lead to increase the risk of health problems. Therefore, the development of functional and dietary forms of these products can help the consumer health. Objective: This study aims to investigate the effects of κ-carrageenan, modified starch and inulin addition on rheological and sensory properties of non-fat and non-added sugar dairy dessert. Methods: In order to determine the viscoelastic behavior of samples, oscillatory test was carried out and the values of storage modulus (G′), loss modulus (G″), loss angle tangent (tan δ) and complex viscosity (η*) were measured. TPA test was used for analysis of the desserts’ texture and textural parameters of samples containing different concentrations of carrageenan, starch and inulin were calculated. Results: All treatments showed a viscoelastic gel structure with the storage modulus higher than the loss modulus values. Increasing amounts of κ-carrageenan and modified starch caused an increase in G′ and G″ as well as η* and a decrease in tan δ. Also, firmness and cohesiveness were enhanced. The trained panelists gave the highest score to the treatment with 0.1% κ-carrageenan, 2.5% starch and 5.5% inulin (sucralose as constant = 0.25%) and this sample was the best treatment with desirable attributes for the production of non-fat and non-added sugar dairy dessert. Conclusion: It can be concluded that the concentration of κ-carrageenan and starch strongly influenced the rheological and textural properties of dairy desserts, whereas the inulin content had little effect on these attributes.

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Effect of Nanofiller Content on Dynamic Mechanical and Thermal Properties of Multi-Walled Carbon Nanotube and Montmorillonite Nanoclay Filler Hybrid Shape Memory Epoxy Composites

Polymers ◽

10.3390/polym13050700 ◽

2021 ◽

Vol 13 (5) ◽

pp. 700

Author(s):

Muhamad Hasfanizam Mat Yazik ◽

Mohamed Thariq Hameed Sultan ◽

Mohammad Jawaid ◽

Abd Rahim Abu Talib ◽

Norkhairunnisa Mazlan ◽

...

Keyword(s):

Shape Memory ◽

High Performance ◽

Loss Modulus ◽

Decomposition Temperature ◽

Hybrid Nanocomposites ◽

Mechanical And Thermal Properties ◽

Scanning Calorimetry ◽

Hybrid Filler ◽

Dynamic Mechanical ◽

Tan Δ

The aim of the present study has been to evaluate the effect of hybridization of montmorillonite (MMT) and multi-walled carbon nanotubes (MWCNT) on the thermal and viscoelastic properties of shape memory epoxy polymer (SMEP) nanocomposites. In this study, ultra-sonication was utilized to disperse 1%, 3%, and 5% MMT in combination with 0.5%, 1%, and 1.5% MWCNT into the epoxy system. The fabricated SMEP hybrid nanocomposites were characterized via differential scanning calorimetry, dynamic mechanical analysis, and thermogravimetric analysis. The storage modulus (E’), loss modulus (E”), tan δ, decomposition temperature, and decomposition rate, varied upon the addition of the fillers. Tan δ indicated a reduction of glass transition temperature (Tg) for all the hybrid SMEP nanocomposites. 3% MMT/1% MWCNT displayed best overall performance compared to other hybrid filler concentrations and indicated a better mechanical property compared to neat SMEP. These findings open a way to develop novel high-performance composites for various potential applications, such as morphing structures and actuators, as well as biomedical devices.

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Electrical conductivity and rheological properties of carbon black based conductive polymer composites prior to and after annealing

Polymers and Polymer Composites ◽

10.1177/09673911211001277 ◽

2021 ◽

pp. 096739112110012

Author(s):

Qingsen Gao ◽

Jingguang Liu ◽

Xianhu Liu

Keyword(s):

Electrical Conductivity ◽

Carbon Black ◽

Percolation Threshold ◽

Rheological Properties ◽

Network Formation ◽

Loss Modulus ◽

Conductive Polymer ◽

Complex Viscosity ◽

Electrical Percolation ◽

Electrical Percolation Threshold

The effect of annealing on the electrical and rheological properties of polymer (poly (methyl methacrylate) (PMMA) and polystyrene (PS)) composites filled with carbon black (CB) was investigated. For a composite with CB content near the electrical percolation threshold, the formation of conductive pathways during annealing has a significant impact on electrical conductivity, complex viscosity, storage modulus and loss modulus. For the annealed samples, a reduction in the electrical and rheological percolation threshold was observed. Moreover, a simple model is proposed to explain these behaviors. This finding emphasizes the differences in network formation with respect to electrical or rheological properties as both properties belong to different physical origins.

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Elastic Properties and Energy Loss Related to the Disorder–Order Ferroelectric Transitions in Multiferroic Metal–Organic Frameworks [NH4][Mg(HCOO)3] and [(CH3)2NH2][Mg(HCOO)3]

Materials ◽

10.3390/ma14113125 ◽

2021 ◽

Vol 14 (11) ◽

pp. 3125

Author(s):

Zhiying Zhang ◽

Hongliang Yu ◽

Xin Shen ◽

Lei Sun ◽

Shumin Yue ◽

...

Keyword(s):

Phase Transition ◽

Energy Loss ◽

Elastic Properties ◽

Ferroelectric Phase ◽

Loss Modulus ◽

Structural Phase ◽

Metal Organic Frameworks ◽

First Order ◽

Metal Organic ◽

Elastic Anomalies

Elastic properties are important mechanical properties which are dependent on the structure, and the coupling of ferroelasticity with ferroelectricity and ferromagnetism is vital for the development of multiferroic metal–organic frameworks (MOFs). The elastic properties and energy loss related to the disorder–order ferroelectric transition in [NH4][Mg(HCOO)3] and [(CH3)2NH2][Mg(HCOO)3] were investigated using differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). The DSC curves of [NH4][Mg(HCOO)3] and [(CH3)2NH2][Mg(HCOO)3] exhibited anomalies near 256 K and 264 K, respectively. The DMA results illustrated the minimum in the storage modulus and normalized storage modulus, and the maximum in the loss modulus, normalized loss modulus and loss factor near the ferroelectric transition temperatures of 256 K and 264 K, respectively. Much narrower peaks of loss modulus, normalized loss modulus and loss factor were observed in [(CH3)2NH2][Mg(HCOO)3] with the peak temperature independent of frequency, and the peak height was smaller at a higher frequency, indicating the features of first-order transition. Elastic anomalies and energy loss in [NH4][Mg(HCOO)3] near 256 K are due to the second-order paraelectric to ferroelectric phase transition triggered by the disorder–order transition of the ammonium cations and their displacement within the framework channels, accompanied by the structural phase transition from the non-polar hexagonal P6322 to polar hexagonal P63. Elastic anomalies and energy loss in [(CH3)2NH2][Mg(HCOO)3] near 264 K are due to the first-order paraelectric to ferroelectric phase transitions triggered by the disorder–order transitions of alkylammonium cations located in the framework cavities, accompanied by the structural phase transition from rhombohedral R3¯c to monoclinic Cc. The elastic anomalies in [NH4][Mg(HCOO)3] and [(CH3)2NH2][Mg(HCOO)3] showed strong coupling of ferroelasticity with ferroelectricity.

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Thermal, Physical and Mechanical Properties of Poly(Butylene Succinate)/Kenaf Core Fibers Composites Reinforced with Esterified Lignin

Polymers ◽

10.3390/polym13142359 ◽

2021 ◽

Vol 13 (14) ◽

pp. 2359

Author(s):

Harmaen Ahmad Saffian ◽

Masayuki Yamaguchi ◽

Hidayah Ariffin ◽

Khalina Abdan ◽

Nur Kartinee Kassim ◽

...

Keyword(s):

Mechanical Properties ◽

Tensile Strength ◽

Loss Modulus ◽

Physical And Mechanical Properties ◽

Weight Percent Gain ◽

Weight Percent ◽

Esterification Reaction ◽

Butylene Succinate ◽

Kenaf Core ◽

Modified Lignin

In this study, Kraft lignin was esterified with phthalic anhydride and was served as reinforcing filler for poly(butylene succinate) (PBS). Composites with different ratios of PBS, lignin (L), modified lignin (ML) and kenaf core fibers (KCF) were fabricated using a compounding method. The fabricated PBS composites and its counterparts were tested for thermal, physical and mechanical properties. Weight percent gain of 4.5% after lignin modification and the FTIR spectra has confirmed the occurrence of an esterification reaction. Better thermo-mechanical properties were observed in the PBS composites reinforced with modified lignin and KCF, as higher storage modulus and loss modulus were recorded using dynamic mechanical analysis. The density of the composites fabricated ranged from 1.26 to 1.43 g/cm3. Water absorption of the composites with the addition of modified lignin is higher than that of composites with unmodified lignin. Pure PBS exhibited the highest tensile strength of 18.62 MPa. Incorporation of lignin and KCF into PBS resulted in different extents of reduction in tensile strength (15.78 to 18.60 MPa). However, PBS composite reinforced with modified lignin exhibited better tensile and flexural strength compared to its unmodified lignin counterpart. PBS composite reinforced with 30 wt% ML and 20 wt% KCF had the highest Izod impact, as fibers could diverge the cracking propagation of the matrix. The thermal conductivity value of the composites ranged from 0.0903 to 0.0983 W/mK, showing great potential as a heat insulator.

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A Characterization Study of Morphology and Properties of Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH)/Aloe Vera Fibers Biocomposites: Effect of Fiber Surface Treatments

Proceedings ◽

10.3390/cgpm2020-07183 ◽

2020 ◽

Vol 69 (1) ◽

pp. 38

Author(s):

Celia Idres ◽

Mustapha Kaci ◽

Nadjet Dehouche ◽

Idris Zembouai ◽

Stéphane Bruzaud

Keyword(s):

Thermal Stability ◽

Surface Morphology ◽

Water Absorption ◽

Loss Modulus ◽

Aloe Vera ◽

Fiber Surface ◽

Complex Viscosity ◽

Absorption Capacity ◽

Characterization Study ◽

Efficient Route

This paper aims to investigate the effect of different chemical modifications of biocomposites based on poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH) and aloe vera bio-fibers incorporated at 20 wt%. The fiber surface was modified with alkaline, organosilanes, and combined alkaline/organosilanes. Surface morphology, thermal stability, water absorption capacity, and rheological behavior of the modified biocomposite materials were studied, and the results compared to both unmodified biocomposites and neat PHBH. The study showed that the modified biocomposites with both alkaline and organosilanes exhibited an improved surface morphology, resulting in a good fiber/matrix interfacial adhesion. As a result, increases in complex viscosity, storage modulus, and loss modulus were observed, whereas water absorption was reduced. Thermal stability remained almost unchanged, with the exception of the biocomposite treated with alkaline, where this property decreased significantly. Finally, the coupling of alkaline and organosilane modification is an efficient route to enhance the properties of PHBH biocomposites.

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High-temperature friction characteristics of N-BK7 glass and their correlation with viscoelastic loss modulus

Ceramics International ◽

10.1016/j.ceramint.2021.04.151 ◽

2021 ◽

Author(s):

Jian Zhou ◽

Hongkun Xu ◽

Chenyu Zhu ◽

Wentao Ai ◽

Xiaojun Liu ◽

...

Keyword(s):

High Temperature ◽

Loss Modulus ◽

Friction Characteristics ◽

Bk7 Glass

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Rheological and Textural Properties of Apple Pectin-Based Composite Formula with Xanthan Gum Modification for Preparation of Thickened Matrices with Dysphagia-Friendly Potential

Polymers ◽

10.3390/polym13060873 ◽

2021 ◽

Vol 13 (6) ◽

pp. 873

Author(s):

Huaiwen Yang ◽

Chai-Chun Tsai ◽

Jung-Shiun Jiang ◽

Chi-Chung Hua

Keyword(s):

Storage Modulus ◽

Water Consumption ◽

Xanthan Gum ◽

Loss Modulus ◽

Textural Properties ◽

Apple Pectin ◽

Composite Matrix ◽

Low Concentrations ◽

Composite Formula

Modifying the consistency of a given edible fluid matrix by incorporating food thickeners is a common nursing remedy for individuals with dysphagia when adequate water consumption is a concern. As apple pectin (AP) offers nutraceutical benefits, properly formulated apple pectin (AP)-based thickeners featuring xanthan gum (XG) can be superior candidates for preparation of dysphagia-friendly matrices (DFMs). Our recruited DFMs exhibit fluid-like behavior (loss modulus > storage modulus, G” > G’) at lower AP concentrations (2 and 5%, w/w); they turn into weak/critical gels (G’ ≈ G”) as the concentration becomes higher (9%). In contrast, XG-DFMs display gel-like attributes with G’ > G”, even at rather low concentrations (<1%) and become more resistant to sugar, Na+, and Ca2+ modifications. The composite matrix of AP1.8XG0.2 (constraint at 2%) exhibits a confined viscosity of 278 ± 11.7 mPa∙s, which is considered a DFM, in comparison to only AP- or XG-thickened ones. The hardness measurements of XG0.6 and AP1.2XG0.8 are 288.33 ± 7.506 and 302.00 ± 9.849 N/m2, respectively, which potentially represent a promising formulation base for future applications with DFMs; these textural values are not significantly different from a commercially available product (p > 0.05) for dysphagia nursing administrations.

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Impact of high-pressure homogenization on the microstructure and rheological properties of citrus fiber

International Journal of Food Engineering ◽

10.1515/ijfe-2020-0206 ◽

2020 ◽

Vol 0 (0) ◽

Author(s):

Dianbin Su ◽

Xin-Di Zhu ◽

Yong Wang ◽

Dong Li ◽

Li-Jun Wang

Keyword(s):

Particle Size ◽

High Pressure ◽

Rheological Properties ◽

Binding Capacity ◽

Loss Modulus ◽

High Pressure Homogenization ◽

Carreau Model ◽

Hydration Properties ◽

Water Binding ◽

Water Holding

Abstract Citrus fiber dispersion with different concentrations (5–25 g/kg) was treated by high-pressure homogenization (90 and 160 MPa) for two cycles. The particle size distribution, hydration properties of powders, morphology and rheological measurements were carried out to study the microstructure and rheological properties changes by high-pressure homogenization (HPH). In conclusion, the HPH can reduce the particle size of fiber, improve the water holding capacity and water binding capacity. Furthermore, fiber shape can be modified from globular cluster to flake-like slices, and tiny pores can be formed on the surface of citrus fiber. The apparent viscosity, storage modulus and loss modulus were increased by HPH whereas the activation energy was reduced. The Hershcel–Bulkley model, Carreau model and Power Law mode were selected to evaluate the rheological properties.

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