Effect of clay modification on the dynamic mechanical and dielectric properties of PMMA nanocomposites via melt blending

e-Polymers ◽  
2012 ◽  
Vol 12 (1) ◽  
Author(s):  
Yeh Wang ◽  
Wei-C. Chen
Keyword(s):  
Dielectric Properties ◽  
Ionic Conduction ◽  
Interfacial Polarization ◽  
Ionic Species ◽  
Space Charge Polarization ◽  
Melt Blending ◽  
Dynamic Mechanical ◽  
Clay Modification ◽  
Β Relaxation ◽  
Clay Layers

AbstractThe dynamic mechanical and dielectric properties of poly(methyl methacrylate)/ clay nanocomposites (PCNs) prepared with melt blending was studied in terms of clay modification and nanoscale dispersion. The pristine clay was modified via various routes, including PMMA concentrates from in situ polymerization and POP-diamine intercalation. Partially exfoliated clay layers were uniformly dispersed in the nanocomposites as evidenced from x-ray diffraction study. The subglass β relaxation, the segmental α relaxation, and the α β-merging process above Tg were observed in the nanocomposites from the dielectric analysis. Compared to neat PMMA, with only 5 wt% clay loading, the modified PCN materials exhibit higher glass-transition temperatures and higher dynamic storage moduli, which was attributed to the polymer chain tethering and confinement effect. Significant increase in dielectric permittivity’s and losses due to interfacial polarization and ionic conduction were observed for the PCNs. The intensity of the interfacial polarization process increases with the dispersion degree of clay layers and hence the relaxation process can be assigned to the space charge polarization of the ionic species in the clay intergalleries.

Improving dielectric properties and thermal conductivity of polymer composites with CaCu3Ti4O12 and β-SiC hybrid fillers

2015 ◽  
Vol 08 (03) ◽  
pp. 1540011 ◽  
Author(s):  
Xin Ouyang ◽  
Peng Cao ◽  
Weijun Zhang ◽  
Zhaohui Huang ◽  
Wei Gao
Keyword(s):  
Thermal Conductivity ◽  
Dielectric Constant ◽  
Dielectric Properties ◽  
Dielectric Response ◽  
Interfacial Polarization ◽  
Melt Blending ◽  
Hybrid Fillers ◽  
Different Types ◽  
Thermally Conductive ◽  
Sic Whiskers

In this paper, we report a series of homogeneous polymeric composites with enhanced dielectric properties and thermal conductivity. The composites were constituted of polyvinylidene fluorides (PVDFs) matrix and CaCu 3 Ti 4 O 12 (CCTO) monolithic or CCTO/β- SiC hybrid fillers, and prepared by simple melt blending and hot moulding technique. The influence of different types of fillers and their composition on the dielectric response and thermal conductivity of the obtained composites was studied. Results show that hybrid loading is preferred and a reasonable combination of thermal conductivity (0.80 W⋅m-1⋅K-1), dielectric constant (∼50) and dielectric loss (∼0.07) at 103 Hz was achieved in the PVDF composite containing 40 vol.% CCTO and 10 vol.% β- SiC . The strong dipolar and interfacial polarization derived from the fillers are responsible for the enhancement of the dielectric constant, while the formation of thermally conductive networks/chains by β- SiC whiskers contributes to the improved thermal conductivity.

scholarly journals Starch-Based Fishing Composite Fiber and Its Degradation Behavior

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Wenwen Yu ◽  
Fei Yang ◽  
Lei Wang ◽  
Yongli Liu ◽  
Jiangao Shi
Keyword(s):  
Melt Spinning ◽  
Starch Content ◽  
Reactive Extrusion ◽  
Composite Fiber ◽  
Mechanical Analysis ◽  
Composite Fibers ◽  
Reactive Blending ◽  
Dynamic Mechanical ◽  
One Step ◽  
Β Relaxation

The starch-based fishing composite fibers were prepared by one-step reactive extrusion and melt spinning. The effects of starch contents on the microstructural, thermal, dynamic mechanical, and mechanical properties of starch-based composite fibers were studied. And the degradation behaviors in soil of the fibers were also investigated. The compatibility between starch and HDPE is improved significantly by grafting maleic anhydride (MA) using one-step reactive blending extrusion. As the starch content increased, the melting temperature and the crystallinity of the fibers gradually decreased due to fluffy internal structures. Dynamic mechanical analysis showed that the transition peak α in the high-temperature region was gradually weakened and narrowed with increasing starch content; moreover, a shoulder appeared on the low-temperature side of the α peak was assigned to the β-relaxation related to starch phase. In addition, the mechanical results showed the significant decrease in the breaking strength and increase in the elongation at break of the starch-based composite fibers as the starch content increased. After degradation in soil for 5 months, the surface of the composite fibers had been deteriorated, while flocculent layers were observed and a large number of microfibers appeared. And the weight loss rate of the starch-based composite fibers (5.2~34.8%) significantly increased with increasing starch content (50~90 wt%).

Enhanced dielectric properties of PVDF-HFP/BaTiO3-nanowire composites induced by interfacial polarization and wire-shape

2015 ◽  
Vol 3 (6) ◽  
pp. 1250-1260 ◽  
Author(s):  
Y. Feng ◽  
W. L. Li ◽  
Y. F. Hou ◽  
Y. Yu ◽  
W. P. Cao ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Interfacial Polarization ◽  
Inorganic Content

A high-ε polymer based composite with lower inorganic content (≤10 vol%) has been fabricated using BaTiO3 nanowires as fillers.

Interfacial polarization effects on dielectric properties in flax reinforced polypropylene/strontium titanate composites

2021 ◽  
pp. 124489
Author(s):  
P.V.S. Hari Prashanth ◽  
Elammaran Jayamani ◽  
Kok Heng Soon ◽  
Yat Choy Wong ◽  
Mohammed Rezaur Rahman ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Strontium Titanate ◽  
Interfacial Polarization ◽  
Polarization Effects

Size Dependent Dielectric Properties of TiO2 Nanoparticles

2020 ◽  
Vol 833 ◽  
pp. 147-151
Author(s):  
K.K. Anjali ◽  
A. Uma Maheswari ◽  
Manickam Sivakumar
Keyword(s):  
Dielectric Properties ◽  
Oxygen Vacancies ◽  
Surface Defects ◽  
Peak Shift ◽  
Chemical Precipitation ◽  
Space Charge Polarization ◽  
Precipitation Method ◽  
Bandgap Energy ◽  
Size Dependent ◽  
Mobility Of Charge Carriers

In this study, influence of nanoparticles size on optical and dielectric properties of TiO2 nanoparticles is investigated through thermal treatment of hydrous amorphous titania synthesized by chemical precipitation method at temperatures 300 °C and 600 °C. The average sizes of nanoparticles estimated respectively are ~ 8 nm and ~ 22 nm. Although the optical bandgap energy of both samples remains the same the Eg Raman mode observed at 144 cm-1 for bulk TiO2 is shifted to 150 cm-1 only for nanoparticles calcined at 300 °C. The shift is ascribed to the size as well as higher density of surface defects. Moreover, the presence of surface defects like oxygen vacancies which provide effective sites for catalytic reaction are confirmed by EPR and photoluminescence studies. The oxygen vacancies enhances space charge polarization and consequently results in higher dielectric constant. In addition, the peak shift of loss tangent which determines the mobility of charge carriers is found to be size dependent. Hence calcination temperature has significant influence on defect levels which in turn determine the optical and dielectric properties of TiO2 nanoparticles.

scholarly journals Proton-Enhanced Dielectric Properties of Polyoxometalates in Water under Radio-Frequency Electromagnetic Waves

Materials ◽  
2018 ◽  
Vol 11 (7) ◽  
pp. 1202 ◽  
Author(s):  
Shuntaro Tsubaki ◽  
Shogo Hayakawa ◽  
Tadaharu Ueda ◽  
Tomohiko Mitani ◽  
Ei-ichi Suzuki ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Radio Frequency ◽  
Electromagnetic Waves ◽  
Ionic Conduction ◽  
Silicotungstic Acid ◽  
High Loss ◽  
Grotthuss Mechanism ◽  
Proton Relay ◽  
Organic Solutions ◽  
Loss Factors

Electromagnetic waves, such as microwaves, have been used to enhance various chemical reactions over polyoxometalates. The dielectric properties of catalysts are among the relevant parameters facilitating catalytic reactions under electromagnetic radiation. This study describes the dielectric properties of polyoxometalate catalysts in aqueous and organic solutions to understand the mechanism of interactions between polyoxometalates and electromagnetic waves. Specific loss factors of polyoxometalates were observed at lower frequencies (<1 GHz) by the ionic conduction of the polyoxometalate solution. The evolution of ionic conduction depended strongly on cations rather than anions. Proton-type polyoxometalates exhibited significantly higher loss factors than other cations did. The activation energy for ionic conduction in protonated silicotungstic acid (H4SiW12O40) was significantly low in water (7.6–14.1 kJ/mol); therefore, the high loss factor of protonated polyoxometalates in water was attributed to the proton relay mechanism (i.e., Grotthuss mechanism). The results suggested that the proton relay mechanism at the radio-frequency band is critical for generating selective interactions of polyoxometalates with applied electromagnetic fields.

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