Mean-Field Calculations of the Dynamic Mechanical Properties of Heterogeneous Elastomer Blends

1989 ◽  
Vol 62 (2) ◽  
pp. 305-314 ◽  
Author(s):  
K. A. Mazich ◽  
P. C. Killgoar ◽  
J. A. Ingram
Keyword(s):  
Experimental Data ◽  
Mechanical Properties ◽  
Glass Transition ◽  
Storage Modulus ◽  
Theoretical Calculations ◽  
Mean Field ◽  
Dynamic Mechanical Properties ◽  
Particle Model ◽  
Dynamic Mechanical ◽  
Grain Model

Abstract A method for calculating the dynamic mechanical properties of elastomer blends with co-continuous structures has been presented. The calculations are based on Kerner's packed-grain model for composite media. Comparisons of theoretical calculations with experimental data show that this model closely approximates the viscoelastic properties of blends with a co-continuous structure, at least in the glass-transition regions of the respective blend components. We have also shown that the storage modulus of co-continuous blends may be well-represented by a discrete-particle model. This result can be misleading, however, if the storage modulus alone is calculated and compared with experimental data. A comparison of viscoelastic data (log E′ and tan δ) with calculation clearly distinguishes the models and indicates that the packed-grain model is the correct representation of the structure of co-continuous blends. The agreement between theory and experiment reported above was principally found in the glass-transition regions of the respective components in the elastomer blend. We extended the comparison well into the rubbery region and found that the agreement between Kerner's mean-field theory and the experimental data was poor, particularly for the loss tangent. Different relaxation mechanisms (relaxations over greater periods of time) are available to the blend in the rubbery region of viscoelastic response, and these mechanisms are apparently not accounted for in the mean-field calculations.

The Effects of Chemical Resistance for Nanocomposite Materials via Nano-Silica Addition into Glass Fiber/Epoxy

2013 ◽  
Vol 853 ◽  
pp. 28-33
Author(s):  
Huey Ling Chang ◽  
Chih Ming Chen ◽  
Kung Liang Lin ◽  
Bor Kae Chang
Keyword(s):  
Mechanical Properties ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Glass Fiber ◽  
Epoxy Resin ◽  
Storage Modulus ◽  
Chemical Resistance ◽  
Dynamic Mechanical Properties ◽  
Silica Nanopowder

Nanocomposite samples containing epoxy resin, glass fiber and 0~2 wt.% SiO2 nanopowder are prepared. The effects of SiO2 addition on the chemical resistance, glass transition temperature (Tg) and dynamic mechanical properties of the various samples are then observed. The chemical resistance of the nanocomposite specimens is compared with that of pure glass fiber/epoxy composite specimens when tested in acetone. The results show that the addition of 2 wt.% SiO2 increases the value of storage modulus by 1646MPa compared to that of the sample containing no silica nanopowder. Following immersion in acetone, all the nanocomposite specimen storage modulus decreased, but the addition of SiO2 reduced the decline, where the 2 wt. % samples decrease from 11.76% reduction to 0.84% and no significant change in the Tg compared to that of the sample with no silica nanopowder. Therefore, the experimental results indicate that 2 wt.% SiO2 addition is beneficial in improving chemical resistance, glass transition temperature, and dynamic mechanical properties of epoxy resin / glass fiber nanocomposites.

The evolution of morphology, crystallization and static and dynamic mechanical properties of long glass-fibre–reinforced polypropylene composites under thermo-oxidative ageing

2018 ◽  
Vol 32 (4) ◽  
pp. 544-557 ◽  
Author(s):  
Jing Zhang ◽  
Weidi He ◽  
Yifan Wu ◽  
Na Wang ◽  
Xiaolang Chen ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Glass Transition ◽  
Glass Fibre ◽  
Ageing Time ◽  
Early Period ◽  
Dynamic Mechanical Properties ◽  
Interface Debonding ◽  
Dynamic Mechanical ◽  
Glass Fibre Reinforced ◽  
Oxidative Ageing

In this work, the static and dynamic mechanical properties, crystallization behaviours, and morphology of long glass-fibre–reinforced polypropylene (PP) composites with thermo-oxidative ageing time from 0 day to 50 days at 120°C were investigated and discussed. The static mechanical properties showed a global decrease in tensile, bending and impact strengths with increasing ageing time. From the results obtained by scanning electronic microscopic observations, interface debonding clearly occurred between the glass fibre and PP matrix in the aged samples. The crystallinity ( Xc) of the composites was analyzed by differential scanning calorimetry; annealing process played the leading role in the early period of ageing, while as ageing progressed, the degradation of PP matrix dominated the ageing process and Xc decreased. The dynamic mechanical analysis results indicated that the storage modulus and glass transition temperature of the composites also decreased with prolonging ageing time. Then, the apparent activation energy ( E) of glass transition was calculated by the Arrhenius equation with different scanning frequencies. A higher value of E was obtained for the samples in the later ageing period, which means a higher energy barrier for glass transition.

Correlation of Microstructural Evolution With the Dynamic-Mechanical Viscoelastic Properties of Underfill Under Sustained High Temperature Operation

2020 ◽  
Author(s):  
Pradeep Lall ◽  
Madhu Kasturi ◽  
Haotian Wu ◽  
Ed Davis ◽  
Jeff Suhling
Keyword(s):  
Mechanical Properties ◽  
Glass Transition ◽  
Viscoelastic Properties ◽  
Loss Modulus ◽  
Optical Microscope ◽  
Dynamic Mechanical Properties ◽  
Isothermal Exposure ◽  
Dynamic Mechanical ◽  
Fine Pitch ◽  
Long Time

Abstract Automotive underhood electronics are subjected to high operating temperatures in the neighborhood of 150 to 200°C for prolonged periods in the neighborhood of 10-years. Consumer grade off-the shelf electronics are designed to operate at 55 to 85 °C with a lower use-life of 3 to 5 years. Underfill materials are used to provide supplemental restraint to fine-pitch area array electronics and meet the reliability requirements. In this paper, a number of different underfill materials are subjected to automotive underhood temperatures to study the effect of long time isothermal exposure on microstructure and dynamic-mechanical properties. It has been shown that isothermal aging oxidizes the underfill, which can change the mechanical properties of the material significantly. The oxidation of underfill was studied experimentally by measuring oxidation layer thickness using polarized optical microscope. The effect on the mechanical properties was studied using the dynamic mechanical properties of underfill with DMA (Dynamic Mechanical Analyzer). Two different underfill materials were subjected to three different isothermal exposure, which are below, near and above the glass transition temperature of the underfills. The dynamic mechanical viscoelastic properties like storage modulus, loss modulus, tan delta and their respective glass transition temperatures were investigated. Three point bending mode was used in the DMA with a frequency of 1 Hz operating at 3 °C/min.

Vinylpyridinium ionomers. III. Influence of the matrix glass transition temperature on the dynamic mechanical properties of random acrylate-based systems

1990 ◽  
Vol 68 (7) ◽  
pp. 1228-1232 ◽  
Author(s):  
Denis Duchesne ◽  
Adi Eisenberg
Keyword(s):  
Mechanical Properties ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Butyl Acrylate ◽  
Matrix Material ◽  
Ethyl Acrylate ◽  
Dynamic Mechanical Properties ◽  
Dynamic Mechanical ◽  
The Matrix

The thermal and dynamic mechanical properties of random butyl acrylate- and plasticized ethyl acrylate-based vinylpyridinium ionomers have been investigated. The properties of the ionomers were found to be dependent on the glass transition temperature of the matrix material. Ionomers having a glass transition temperature lower than ca. 25 °C exhibited all the features associated with the presence of phase-separated microdomains or clusters while the materials with higher glass transition temperatures were not. It was also observed that the dispersion associated with the vinylpyridinium clusters for a butyl acrylate-based ionomer with 12 mol% of ionic units occurs at ca. 25 °C. This value is very close to that observed previously by Otocka and Eirich in their study of a butadiene-based vinylpyridinium ionomer with the same ion content. Keywords: ionomers, plasticization, clustering, glass transition, dynamic mechanical properties.

Study on Dynamic Mechanical Properties of n-HA/PA66 Composites

2011 ◽  
Vol 418-420 ◽  
pp. 1511-1515
Author(s):  
Lin Cheng ◽  
Xiang Zhang ◽  
Yu Bao Li
Keyword(s):  
Mechanical Properties ◽  
Storage Modulus ◽  
Loss Modulus ◽  
Physiological Saline ◽  
Dynamic Mechanical Properties ◽  
Intrinsic Properties ◽  
Polyamide 66 ◽  
Dynamic Mechanical ◽  
Reinforcing Effects

The dynamic mechanical properties of nano-hydroxyapatite (n-HA) reinforced polyamide 66 (PA66) biocomposites were studied with reference to the effect of n-HA content, frequency and physiological saline. The intrinsic properties of the components, morphology of the system and the nature of interface between the phases determine the dynamic mechanical properties of the composite. The storage modulus (E') values of n-HA/PA66 composites were much higher than those of pure PA66, indicating that the incorporation of n-HA in PA66 matrix induced reinforcing effects obviously. And the E' values of composites increased with increasing of n-HA content. The loss modulus (E") of the composite with 30wt% n-HA was higher that those of pure PA66 and the composite with 40wt% n-HA below 55°C, however, above 55°C, the E" values enhanced with increase of n-HA content. Both frequency and physiological saline had obvious effects on the dynamic mechanical properties for n-HA/PA66 composite. E' and E" values enhanced with increase of frequency, but tanδ values decreased with increasing of frequency. After soaked in physiological saline, the E' and E" values of the composite decreased.

DYNAMIC MECHANICAL PROPERTIES OF NANOCOMPOSITES WITH POLY (VINYL BUTYRAL) MATRIX

2010 ◽  
Vol 24 (06n07) ◽  
pp. 805-812 ◽  
Author(s):  
A. M. TORKI ◽  
I. ŽIVKOVIĆ ◽  
V. R. RADMILOVIĆ ◽  
D. B. STOJANOVIĆ ◽  
V. J. RADOJEVIĆ ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Storage Modulus ◽  
Dynamic Mechanical Properties ◽  
Titania Nanoparticles ◽  
Mixing Process ◽  
Melt Mixing ◽  
Dynamic Mechanical ◽  
The Matrix ◽  
Silica And Titania ◽  
Vinyl Butyral

This work reports the preparation of SiO 2 and TiO 2/poly (vinyl butyral) nanocomposites with enhanced dynamic mechanical properties. Silica and titania nanoparticles were introduced in the matrix as the neat powder and as colloidal sol using the melt mixing process. Composites reinforced with colloidal sol silica and titania showed higher mechanical properties than the ones reinforced with as-received particles. When sol TiO 2 particles are used, the highest increase of storage modulus of about 54% is obtained for 5 wt% loading, while for sol SiO 2, the storage modulus increases with the addition of nanosilica with the largest increase of about 99% for 7 wt% loading. In addition, nanocomposites were introduced within Kevlar/PVB composites. The addition of 5 wt% silica and titania colloidal sol lead to the remarkable increase of the storage modulus for about 98 and 65%, respectively. Largest contribution of nanoreinforcements in lowering the glass transition temperature is observed for 7 wt% loading of TiO 2 and SiO 2 colloidal sol.

Study of Microstructure and Dynamic Mechanical Analysis of Biodegradable Tableware Produced with Corn Straw

2011 ◽  
Vol 380 ◽  
pp. 160-163 ◽  
Author(s):  
Alun ◽  
Zhi Hui Sun ◽  
Quan Rong Jing ◽  
Ri Dun Hu ◽  
Chun Li Yang
Keyword(s):  
Mechanical Properties ◽  
Mechanical Property ◽  
Storage Modulus ◽  
Dynamic Mechanical Properties ◽  
Mechanical Analysis ◽  
Dynamic Mechanical Property ◽  
Corn Straw ◽  
Dynamic Mechanical ◽  
Scan Electronic Microscope ◽  
Electronic Microscope

This paper focused on biodegradable tableware processed with plant fiber, which were obtained by mechanical processing corn straw, abundant in Heilongjiang Province of China. Firstly, the microstructure characteristics of tableware were described by Scan Electronic Microscope (SEM). Secondly, the dynamic mechanical property of biodegradable tableware was analyzed by DMA, which will provide a reference to optimize the biodegradable tableware design in future. And the dynamic mechanical property of biodegradable tableware also was compared with the dynamic mechanical properties of the plastic snack box. The results showed that biodegradable tableware had a highly storage modulus (E′) originally, it was 3216MPa,while the maximum storage modulus (E′) of plastic snack box was 852MPa. And the results also indicated that the treat temperature has a significant effect on the dynamic mechanical properties of biodegradable tableware, as the treat temperature increased closely to 95°C, the biodegradable tableware appeared glassy transition, but the storage modulus (1650MPa) was still much higher than that of the plastic snack box.

Sign in / Sign up

Export Citation Format

Share Document