Dynamic nanomechanical response of nacre

2006 ◽  
Vol 21 (8) ◽  
pp. 2045-2051 ◽  
Author(s):  
Bedabibhas Mohanty ◽  
Kalpana S. Katti ◽  
Dinesh R. Katti ◽  
Devendra Verma
Keyword(s):  
Mechanical Properties ◽  
Loss Factor ◽  
Dynamic Properties ◽  
Loss Modulus ◽  
Spectroscopic Studies ◽  
Increase With Increase ◽  
Nanocomposite System ◽  
Brick And Mortar ◽  
Tan Δ ◽  
Dynamic Nanoindentation

Nacre, the shiny inner layer of mollusk shells is a model biomimetic nanocomposite system. Its exceptional mechanical properties have been the inspiration for materials scientists for several decades. Nacre exhibits a layered brick and mortar structure. It is composed of 95% inorganic (aragonitic CaCO3) phase and 5% organic (mainly proteins and polysaccharides) phase that are arranged in interlocked brick and mortar architecture with the mineral as bricks and organics as the mortar. In the current work, we describe the dynamic nanomechanical behavior of nacre using dynamic nanoindentation (nano-DMA) experiments. Two sets of loads were applied to obtain the dynamic response from varying depths in nacre. These tests were performed at three different frequencies (25, 50, and 100 Hz) to study the effect of frequency on the dynamic properties of nacre. The loss modulus (E″) and the loss factor (tan δ) were measured. Both of these parameters were observed to increase with increase in depth. Significant increase in tan δ was observed with the increase in frequency. Photoacoustic Fourier transform infrared spectroscopic studies on nacre indicate the presence of water in nacre. This water may be present at nanograin interfaces in nacre platelets, at organic–inorganic interfaces, and also in the organic phase in nacre. We believe that water is one of the significant contributors to the viscoelasticity of nacre. Our results indicate that the aragonite platelets in nacre may also contribute to viscoelasticity.

Quasi-static and dynamic nanoindentation to determine the influence of thermal treatment on the mechanical properties of bamboo cell walls

Holzforschung ◽  
2015 ◽  
Vol 69 (7) ◽  
pp. 909-914 ◽  
Author(s):  
Yanjun Li ◽  
Liping Yin ◽  
Chengjian Huang ◽  
Yujie Meng ◽  
Feng Fu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Thermal Treatment ◽  
Cell Walls ◽  
Loss Modulus ◽  
Treatment Temperature ◽  
Dry Density ◽  
Bamboo Fibers ◽  
Tan Δ ◽  
Dynamic Nanoindentation

Abstract Bamboo was thermally treated at 180°C and 200°C, and the micromechanical properties of its cell walls were investigated by means of quasi-static and dynamic nanoindentation experiments. With increasing treatment temperatures, the average dry density and mass of the bamboo decreased, whereas the already reduced elastic modulus at 180°C of the fiber cell walls did not change, but the hardness showed increasing tendencies. Dynamic nanoindentation revealed reduced storage modulus $({E'_{\rm{r}}})$ and loss modulus $({E''_{\rm{r}}}\,)$ for the thermotreated bamboo cell walls compared with the untreated bamboo fibers in all frequency regions. Moreover, ${E'_{\rm{r}}},{\rm{ }}{E''_{\rm{r}}},$ and loss tangent (tan δ) of treated bamboo decreased with increasing treatment temperature.

Dynamic Mechanical Analysis of Bio-Based and Synthetic Petroleum Based Polymer Foams with Powder Type Organic Filler at Prolonged Ultra-Violet Exposure

2020 ◽  
Vol 01 (01) ◽  
Author(s):  
M A Zulhakimie ◽  
◽  
Anika Zafiah M. Rus ◽  
N S S Sulong ◽  
A Syah Z A ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Epoxy Polymer ◽  
Loss Modulus ◽  
Ultra Violet ◽  
Mechanical Analysis ◽  
Uv Exposure ◽  
Polymer Foams ◽  
Polymer Foam ◽  
Powder Filler ◽  
Tan Δ

Wood powder filler applied to the bio-based and epoxy polymer foams has the potential to reinforce the polymer foam structure. The 'Meranti' wood filler type was used as the filler in this analysis. In order to observe the pore size of each sample when exposed to different hours of UV exposure using optical microscopy (OM), this study was made.This analysis was conducted to compare the mechanical properties of each sample with different filler ratios of 0 wt%, 5 wt%, 10 wt%, 15wt% and 20 wt% at different UV exposure hours, which is 0 hour to 6000 hours with a 2000 hour rapid increase. Using the DMA Q800 TA unit, the mechanical properties were studied. In order to obtain the product of their mechanical properties, samples having a scale of 40 x 10 x 5 mm were clamped into the machine. The results will show the value of tan δ, loss modulus and storage modulus from the DMA test.The tan δ value shows that the high tanδvalue will be produced by the higher ratio filler. In contrast to bio-based polymer foams, epoxy polymer foams with powder fillers have the highest tan δ value. It shows that the higher filler ratio can be reported with the lower tan δ value. As the filler ratio filler in the polymer foams increased, the consequence of storage and loss modulus was found to increase. The greater the modulus of loss and the modulus of storage, the lower the temperature. As energy is lost as heat during UV irradiation exposure, bio-based polymer foams with a high powder filler ratio can dissipate more energy.

scholarly journals Use of waste materials in rubber matrix

2018 ◽  
Vol 157 ◽  
pp. 07009 ◽  
Author(s):  
Mariana Pajtášová ◽  
Zuzana Mičicová ◽  
Darina Ondrušová ◽  
Slavomíra Božeková ◽  
Róbert Janík ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Loss Modulus ◽  
Rolling Resistance ◽  
Dynamic Mechanical Properties ◽  
Waste Materials ◽  
Partial Replacement ◽  
Rubber Matrix ◽  
Loss Angle ◽  
Rubber Compounds ◽  
Tan Δ

The presented paper deals with the use of waste materials as ecological fillers into rubber matrix. Waste materials were used as partial replacement of the commercial filler – carbon black, designated as N339. These prepared rubber compounds were characterized on the basis of the rheology and vulcanization characteristics – minimum torque (ML), maximum torque (MH), optimum time of vulcanization (t(c90)), processing safety of compound (ts), rate coefficient of vulcanization (Rv). In the case of the prepared vulcanizates, physical-mechanical properties (tensile strength, tensibility and hardness) and dynamic-mechanical properties (storage modulus, loss modulus, loss angle tan δ) were investigated. Using the dependency of loss angle on temperature, the selected properties for tyre tread vulcanizates were evaluated, including traction on snow and ice, traction on the wet surface and rolling resistance.

Mechanical and Dynamic Properties of Silica-Filled Rubber Compounds

2013 ◽  
Vol 781-784 ◽  
pp. 475-478
Author(s):  
Watcharin Rassamee ◽  
Woothichai Thaijaroen ◽  
Thirawudh Pongprayoon
Keyword(s):  
Mechanical Properties ◽  
Dynamic Properties ◽  
Rolling Resistance ◽  
Rubber Compound ◽  
Cure Characteristics ◽  
Rubber Compounds ◽  
Silane Coupling ◽  
Unmodified Silica ◽  
Tan Δ ◽  
Wet Grip

Natural rubber compound using different silicas, including unmodified silica, admicellar-modified silica and silica with silane coupling agent, were studied. The properties including cure characteristics, mechanical properties and dynamic properties were examined with the comparison of three compounds. The results show that cure characteristics of admicellar silica/rubber compound (Ad-Si/R) was shorter than those of unmodified silica/rubber compound (Un-Si/R) and silane coupling silica/rubber compound (Sil-Si/R). Mechanical properties of Ad-Si/R and Sil-Si/R were better than those of Un-Si/R. In addition, wet grip and rolling resistance analyzed from tan δ (5 Hz) at 0°C and 60°C, respectively, by DMA were found that the wet grip of Ad-Si/R was the best, whereas the rolling resistance of Sil-Si/R was the best, in the comparison.

The Property of Waterborne UV-Curable Polyurethane Based on Alkali Lignin of Wheat Straw

2013 ◽  
Vol 834-836 ◽  
pp. 199-202 ◽  
Author(s):  
Ji Lei Chao ◽  
Fu Qiang Chu ◽  
Chang Li Xu ◽  
Hui Wang ◽  
Yu Xin Liu
Keyword(s):  
Mechanical Properties ◽  
Optical Properties ◽  
Wheat Straw ◽  
Loss Factor ◽  
Loss Modulus ◽  
Added Value ◽  
Light Transmittance ◽  
Optical Performance ◽  
Uv Curable ◽  
Alkali Lignin

To improve the added value of lignin, the modified alkali lignin of wheat straw was used to prepare waterborne UV-curable polyurethane. The purpose of this paper is to discuss the properties of the cured films made from the above lignin-based polyurethane. The mechanical and optical properties of the cured films were investigated. Results showed that the tensile storage modulus, tensile loss modulus, and tensile loss factor of the cured film were influenced by the addition of the lignin, which indicated that proper dosage of the lignin could change the micro-phase separation structure and improve the mechanical properties of the product. The addition of the lignin also influenced the gloss and light transmittance of the cured film. On the whole, the lignin-based polyurethane exhibits good mechanical and optical performance if proper proportion of the lignin was added to the product. The study was beneficial for utilizing the lignin in high value products.

scholarly journals Effect of Ultraviolet-A (UV-A) and Ultraviolet-C (UV-C) Light on Mechanical Properties of Oyster Mushrooms during Growth

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Tindibale L. Edward ◽  
M. S. K. Kirui ◽  
Josiah O. Omolo ◽  
Richard G. Ngumbu ◽  
Peter M. Odhiambo
Keyword(s):  
Mechanical Properties ◽  
Storage Modulus ◽  
Loss Factor ◽  
Loss Modulus ◽  
Control Sample ◽  
Ultraviolet A ◽  
Significant Difference ◽  
Ultraviolet C ◽  
Oyster Mushrooms ◽  
Uv C

This study investigated the effects of ultraviolet-A (UV-A) and ultraviolet-C (UV-C) light on the mechanical properties in oyster mushrooms during the growth. Experiments were carried out with irradiation of the mushrooms with UV-A (365 nm) and UV-C (254 nm) light during growth. The exposure time ranged from 10 minutes to 60 minutes at intervals of 10 minutes and irradiation was done for three days. The samples for experimental studies were cut into cylindrical shapes of diameter 12.50 mm and thickness 3.00 mm. The storage modulus, loss modulus, and loss factor of the irradiated samples and control samples were determined for both UV bands and there was a significant difference between the storage modulus, loss modulus, and loss factor of the irradiated samples by both UV bands with reference to the control sample, P<0.05. UV-C light irradiated samples had higher loss modulus and loss factor but low storage modulus as temperature increased from 35 to 100°C with respect to the control sample while UV-A light irradiated samples had lower loss modulus, low loss factor, and higher storage modulus than UV-C irradiated samples.

EFFECTS OF 4,4′-BISMALEIMIDODIPHENYLMETHANE CURING AGENT ON MORPHOLOGICAL, RHEOLOGICAL, AND MECHANICAL PROPERTIES OF DYNAMICALLY VULCANIZED BIIR/POLYPROPYLENE ELASTOMERS

2018 ◽  
Vol 92 (2) ◽  
pp. 298-309 ◽  
Author(s):  
Fang Wang ◽  
Aiming Zhang ◽  
Tao Zhou
Keyword(s):  
Mechanical Properties ◽  
Loss Modulus ◽  
Complex Viscosity ◽  
Continuous Phase ◽  
Curing Agent ◽  
Capillary Rheometer ◽  
Dynamic Vulcanization ◽  
Opposite Trend ◽  
Tan Δ ◽  
Pp Blends

ABSTRACT The morphological, rheological, and mechanical properties of BIIR/polypropylene (PP) blends with various amounts of 4,4′-bismaleimidodiphenylmethane (BMI) curing agent were studied. As the level of BMI curing agent increased, the rubber single particle size decreased, but the interaction among the particles strengthened to form aggregates. The rheological properties were determined with a high-pressure capillary rheometer and a rotational rheometer. It was found that the rheological behavior was affected by both the BMI content and the morphology of the blends. The increased BMI content led to the smaller vulcanized BIIR rubber particles dispersing in the PP continuous phase because of the improvement in cross-linking speed and degree as well as the viscosity of BIIR. The dynamic vulcanization strongly improved the elasticity of the blends. The storage modulus, loss modulus, and complex viscosity of cured BIIR/PP blends were all obviously higher than those of the uncured blend, whereas the values of tan δ showed the opposite trend. The as-prepared BIIR/PP thermoplastic vulcanizate exhibited suitable hardness and good mechanical properties.

An Investigation on the Viscoelastic Behavior of Eggshell Membrane by Nanoindentation Technology

2019 ◽  
Vol 11 (08) ◽  
pp. 1950078
Author(s):  
Qing-Sheng Yang ◽  
Shuai-Wei Li ◽  
Jia-Qi Zhu ◽  
Xiang Li
Keyword(s):  
Loss Factor ◽  
Measurement Method ◽  
Loading Rate ◽  
Loss Modulus ◽  
Viscoelastic Behavior ◽  
Eggshell Membrane ◽  
Viscous Damping ◽  
Dependent Behavior ◽  
Level Loading ◽  
Dynamic Nanoindentation

The mechanical properties of eggshell membrane (ESM) are comparable to those of human patellar tendon or skin. This paper, based on static and dynamic nanoindentation technique, studied the time-dependent behavior, i.e., creep and relaxation of the ESM. The effect of loading level, loading rate and holding time on viscoelastic behavior were discussed by using the static measurement method of nanoindentation. The storage modulus, loss modulus and loss factor were obtained as a function of frequency. It was found that the outer membrane (OM) exhibits more apparent relaxation properties and stronger capacity to resist creep deformation than that of the inner membrane (IM). In addition, the loss factor of the IM is larger than that of the OM which caused a larger viscous damping of IM. This work can contribute to the bioinspired applications of ESM.

Dynamic Mechanical Analysis of Polyurethane-Epoxy Interpenetrating Polymer Networks

2009 ◽  
Vol 21 (5) ◽  
pp. 608-623 ◽  
Author(s):  
Mariana Cristea ◽  
Sorin Ibanescu ◽  
Constantin N. Cascaval ◽  
Dan Rosu
Keyword(s):  
Activation Energy ◽  
Molecular Dynamics ◽  
Dynamic Mechanical Analysis ◽  
Loss Factor ◽  
Loss Modulus ◽  
Polymer Networks ◽  
Mechanical Analysis ◽  
Interpenetrating Polymer Networks ◽  
Dynamic Mechanical ◽  
Tan Δ

A series of semi-interpenetrated polymer networks based on bisphenol A epoxy resin and polyurethane was synthesized by sequential procedure. The molecular dynamics of polyurethane incorporated in the resin network with increasing amounts of resin was followed by dynamic mechanical analysis. All phenomena that concur in the material are evaluated by cross-examination of the storage modulus ( E'), loss modulus ( E'') and loss factor (tan δ) variation with temperature. Complex aspects were elucidated in consecutive heating-cooling-heating cycles and by calculating the apparent activation energy of relaxations in multiplex experiments.

Dynamic Mechanical Properties of NR-HDPE Blends

1987 ◽  
Vol 60 (4) ◽  
pp. 591-599 ◽  
Author(s):  
S. Akhtar ◽  
S. S. Bhagawan
Keyword(s):  
Mechanical Properties ◽  
Carbon Black ◽  
Storage Modulus ◽  
Loss Tangent ◽  
Loss Modulus ◽  
Dynamic Mechanical Properties ◽  
Thermoplastic Elastomers ◽  
Dynamic Mechanical ◽  
Storage And Loss Moduli ◽  
Tan Δ

Abstract Dynamic mechanical properties such as storage modulus, loss modulus, and loss tangent have been evaluated over a wide range of temperatures for thermoplastic elastomers prepared from blends of NR and HDPE. It was observed that above room temperature, both storage and loss moduli increased and loss tangent decreased as the HDPE content in the blend increased. The effects of dynamic crosslinking and carbon black filler on dynamic mechanical behavior of 70/30 NR/HDPE blend were also examined. Carbon black increased the storage and loss moduli but lowered and broadened the tan δ peak. On the other hand, crosslinking increased storage modulus and decreased the loss modulus and loss tangent, particularly after the NR Tg. The tan δ peak area which appeared at Tg for NR was proportional to the rubber content in the blends.

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