Abstract:The effect of the weight fraction of NaA zeolite on thermal properties (specific heat capacity, thermal diffusivity, thermal conductivity) and dielectric properties (electrical conductivity, real and imaginary electric permittivity) of composites based on low-density polyethylene (LDPE) and NaA zeolite is examined. Composite samples containing from 5 to 30 wt% zeolite are prepared using the compression molding technique. The degree of dispersion and the weight fraction of filler in the LDPE/NaA zeolite composi… Show more
“…The dielectric constant, CTE, and density of LLEDP/COC are compared with previously reported thermoplastic composites, 48–58 and the results are presented in Table 4. It can be seen that LLDPE/COC exhibits a relatively good combination of properties compared with its counterparts.…”
Insulation materials with low dielectric constants, low coefficients of thermal expansion (CTE), low densities, renewability, and low cost are urgently needed in the fields of communication, control and signal cables. Here we report that combining cyclic olefin copolymer (COC) with linear low‐density polyethylene (LLDPE) by melt blending achieves the above goals. The dielectric constant and CTE of LLDPE/COC blends are minimized at 20 wt% COC content, reaching a value of 2.23 at 1000 Hz and 1.21 × 10−4 K−1, respectively. The density of the blend increases by only 1.6% compared with LLDPE, whereas the tensile modulus increases by 56%, which is conducive to the blends to improve mechanical strength while preserving lightweight. The rheological tests show that the zero‐shear viscosity, storage modulus, and loss modulus of the LLDPE/COC blends do not change much compared with pristine LLDPE, maintaining their good melt processability at 160°C. The cyclic rigid structure of COC causes a decrease in CTE, and the increase in free volume between molecular chains is responsible for the reduced dielectric constant. The present work provides a promising route to the design and fabrication of melt‐reprocessable polymer composites with low dielectric constant and low thermal expansion.
“…The dielectric constant, CTE, and density of LLEDP/COC are compared with previously reported thermoplastic composites, 48–58 and the results are presented in Table 4. It can be seen that LLDPE/COC exhibits a relatively good combination of properties compared with its counterparts.…”
Insulation materials with low dielectric constants, low coefficients of thermal expansion (CTE), low densities, renewability, and low cost are urgently needed in the fields of communication, control and signal cables. Here we report that combining cyclic olefin copolymer (COC) with linear low‐density polyethylene (LLDPE) by melt blending achieves the above goals. The dielectric constant and CTE of LLDPE/COC blends are minimized at 20 wt% COC content, reaching a value of 2.23 at 1000 Hz and 1.21 × 10−4 K−1, respectively. The density of the blend increases by only 1.6% compared with LLDPE, whereas the tensile modulus increases by 56%, which is conducive to the blends to improve mechanical strength while preserving lightweight. The rheological tests show that the zero‐shear viscosity, storage modulus, and loss modulus of the LLDPE/COC blends do not change much compared with pristine LLDPE, maintaining their good melt processability at 160°C. The cyclic rigid structure of COC causes a decrease in CTE, and the increase in free volume between molecular chains is responsible for the reduced dielectric constant. The present work provides a promising route to the design and fabrication of melt‐reprocessable polymer composites with low dielectric constant and low thermal expansion.
“…In the study, composites containing NaA zeolite additives at rates ranging from 5% to 30% by weight were prepared and it was observed that the thermal conductivity increased as the additive ratio increased. Similarly, a gradual increase in electrical conductivity was detected with increasing zeolite content 10 . Very recently, Al‐Jumaili et al studied the mechanical properties of LDPE/montmorillonite (MMT) films.…”
This study is focused on investigating the role of bismuth oxide (Bi2O3) nanoparticles to improve structural, optical, electrical, and mechanical properties of low‐density polyethylene (LDPE). For this purpose, Bi2O3 nanoparticles were synthesized by using the solvothermal method and examined by transmission electron microscopes (TEM), x‐ray diffraction (XRD), Fourier transformed infrared (FTIR) spectroscopy, and ultraviolet–visible (UV–Vis) light absorption methods. LDPE‐based nanocomposites were prepared by changing the nanoparticle additive ratio in the composite from 0% to 2% by weight. The composites were analyzed in the context of their FTIR spectra, atomic force microscope (AFM) images, UV–Vis light absorption spectra, stress–strain curves, and energy storage abilities. While the AFM findings indicate a smoother surface for the composites, the optical band gap analysis reveals a slightly decreased direct optical band gap energy. The analyses based on dielectric spectroscopy also highlight the LDPE/0.5% n‐Bi2O3 composite in terms of the best energy storage capability. Additionally, the highest Young's modulus, toughness, stress at break, and percentage of strain at break were also recorded for the LDPE/0.5% n‐Bi2O3 composite. In this context, the LDPE/0.5% n‐Bi2O3 composite with improved dielectric and mechanical properties can be suggested as a new promising LDPE‐based nanocomposite with better properties for industrial purposes.
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