High-performance polymer/nanodiamond composites: synthesis and properties

Conjugated polymer/nanodiamond nanocomposites have been known as high-performance materials due to improved physical properties relative to conventional composites. In this attempt, novel conjugated polymer/nanodiamond nanocomposites were successfully prepared by in situ oxidative polymerization. Physical characteristics of the resultant nanocomposites were explored using Fourier transform infrared spectroscopy, field emission scanning electron microscope (FESEM), energy dispersive X-ray spectroscope, differential scanning calorimeter, thermogravimetric analysis and X-ray diffraction spectroscopy. Structural analysis revealed the oxidative polymerization of various matrices [polyaniline (PANi), polypyrrole (PPy), polythiophene (PTh) and polyazopyridine (PAP)] over the surface of functionalized (F-NDs) and non-functionalized nanodiamonds (NF-NDs) thus ensuing NF-NDs/PAP/PANi/PPy, F-NDs/PAP/PANi/PPy, NF-NDs/PANi/PPy/PTh and F-NDs/PANi/PPy/PTh nanocomposites. FESEM images depicted the fibrillar morphology of resulting nanocomposites with granular arrangement of nanofiller in matrix. Thermal analysis results showed that the functionalized F-NDs/PAP/PANi/PPy hybrid had higher value of 10 % weight loss around 489 °C relative to F-NDs/PANi/PPy/PTh with T₁₀ at 471 °C. The glass transition temperature was found to be 99 and 105 °C for NF-NDs/PANi/PPy/PTh and F-NDs/PANi/PPy/PTh, respectively. On the other hand, NF-NDS/PAP/PANi/PPy and F-NDs/PAP/PANi/PPy showed higher T _g’_s of 109 and 118 °C. The conductivity of NF-NDs/PAP/PANi/PPy was 3.8 Scm^?1 and improved with the functionalized filler loading in F-NDs/PAP/PANi/PPy up to 5.4 Scm^?1, while NF-NDs/PANi/PPy/PTh and F-NDs/PANi/PPy/PTh had relatively lower values around 2.9 and 3.7 Scm^?1, respectively. New conducting nanocomposites may act as useful contenders in significant industrial applications such as polymer Li-ion battery.     

Montmorillonite nanoclay filler effects on electrical conductivity,thermal and mechanical properties of epoxy‐based nanocomposites

Epoxy‐based nanocomposites with 2, 5, and 7 wt% of montmorillonite (MMT) nanoclay were prepared using high shear melt mixing technique. The microstructural features of the nanocomposites were investigated by transmission electron microscopy (TEM). The thermal and mechanical properties were measured using differential scanning calorimetry (DSC), thermogravimetric analyzer (TGA), and dynamic mechanical analyzer (DMA). Further, the effect of voltage, temperature, seawater aging on the electrical conductivity (σ_DC) of the nanocomposites was also measured. To understand the free volume behavior upon filler loading, and to observe the connectivity between microstructure and other properties, positron annihilation lifetime spectroscopy was used. The TEM results revealed that MMT nanoparticles were uniformly dispersed in the epoxy matrix. Experimental results showed that the inclusion of 2 wt% MMT nanofiller increased the T_g, electrical conductivity, thermal stability, modulus, free volume of the epoxy nanocomposite significantly. This is well explained from the results of T_g (DSC and DMA), thermal stability, TGA residue, free volume analysis, and electrical conductivity. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers     

Polylactide/transition metal ion modified montmorillonite nanocomposite—a critical evaluation of mechanical performance and thermal stability

Polylactide (PLA) nanocomposite was prepared by melt blending of PLA and transition metal ion (TMI) adsorbed montmorillonite (MMT). PLA nanocomposite was characterized for mechanical performance, and the results revealed that the tensile modulus, flexural modulus, and impact strength were increased marginally. The nanocomposite was optimized at 5 wt% of TMI‐modified MMT (TMI‐MMT) loading. Thermogravimetric analysis displayed increase in onset of degradation temperature, and differential scanning calorimetry showed marginal increase in glass transition temperature (T_g) and melting temperature (T_m) in case of PLA nanocomposites, when compared with virgin PLA. The flammability testing of nanocomposites indicated good fire retardance characters. X‐ray diffraction patterns of TMI‐MMT and the corresponding nanocomposites indicated an intercalation of the metal ions into the clay interlayer. Fourier transform infrared spectroscopy analysis indicate formation of [Zn(EDA)₂]²⁺ and [Cu(EDA)₂]²⁺ complexes in the MMT interlayer. Dynamic mechanical analysis shows increase in glass transition temperature (T_g) and storage modulus (E′) in case of PLA nanocomposites reinforced with 5 wt% modified MMT. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

Effect of Polyhedral Oligomeric Silsesquioxanes Nanoparticles on Thermal and Mechanical Properties of Poly(vinyl chloride) Composite Materials

The modification of poly(vinyl chloride) (PVC) by polyhedral silsesquioxane containing both methacryl and octyl groups (MeOctPOSS) was the task of studies. The PVC nanocomposites with MeOctPOSS concentration between 1 and 10 wt% were prepared by melt mixing processing, and the homogeneity of MeOctPOSS dispersion in the polymeric matrix was confirmed by scanning electron microscopy and energy dispersive spectroscopy observations. The influence of MeOctPOSS on glass transition temperature (T_g) determined by means of dynamic mechanical thermal analysis (DMTA) and differential scanning calorimetry (DSC) was observed, whereas, higher the measurement frequency, higher the glass transition temperature was noted. The MeOctPOSS concentration‐dependent PVC glass transition temperature was shifted from 73.8°C to about 68°C (? = 1 Hz) and from 76.5°C to 70.8°C (? = 10 Hz) for increasing additive content. Similar result of decreasing T_g value was observed by DSC method. An introduction of 10 wt% of MeOctPOSS into the PVC matrix results in a visible decrease of the maximum value of loss modulus (G′) of approximately 12% and 18% by 1 Hz and 10 Hz, respectively, as well as in a significant reduction of the static elastic modulus. It was stated that the polyhedral oligomeric silsesquioxanes with both methacryl and octyl groups may act as plasticizers of the PVC matrix. J. VINYL ADDIT. TECHNOL., 25:E48–E54, 2019. © 2018 Society of Plastics Engineers     

Electroconductive performance of polypyrrole/graphene nanocomposites synthesized through in situ emulsion polymerization

The present study demonstrates a modified in situ emulsion polymerization (EP) approach convenient for the formation of polypyrrole/graphene (PPy/GN) nanocomposites with harnessed conductivities. A series of PPy/GN nanocomposites were prepared by loading different weight percent (wt %) of GN during in situ EP of pyrrole monomer. The polymerization was carried out in the presence of dodecyl benzene sulfonic acid, which acts as an emulsifier and protonating agent. The microstructures of the nanocomposites were studied by scanning electron microscopy, transmission electron microscopy, X‐ray diffraction, Fourier transform infrared, X‐ray photoelectron spectroscopy, UV–vis spectroscopy, Raman spectroscopy, photoluminescence spectroscopy and thermogravimetric analyses. The electrical conductivities of the nanocomposite pellets pressed at different applied pressures were determined using four probe analyzer. The electrical conductivities of the nanocomposites were considerably enhanced as compared to those of the individual PPy samples pressed at the same pressures. An enhanced conductivity of 717.06 S m^?1 was observed in the sample with 5 wt % GN loading and applied pressure of 8 tons. The results of the present study signify that the addition of GN in the PPy polymer harnesses both electrical and thermal properties of the polymer. Thus, PPy/GN nanocomposites with superior properties for various semiconductor applications can be obtained through direct loading of GN during the polymerization process. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41800.     

Hybrid nanocomposites based on novolac resin and octa(phenethyl) polyhedral oligomeric silsesquioxanes (POSS): miscibility, specific interactions and thermomechanical properties

Hybrid nanocomposites were prepared via solution blending of octaphenethyl POSS into novolac resin. The resulted hybrid blends were investigated by Fourier-transformed infrared spectra (FTIR), polarized optical microscopy (POM), wide X-ray diffraction and differential scanning calorimetry (DSC). FTIR results showed that there existed intermolecular hydrogen bond between the hydroxyl groups of the phenolic resin and POSS siloxane groups, which could promote POSS to disperse well in the polymer matrix up to 20 wt% POSS loading. At higher POSS loading, POSS would aggregate and lead to macrophase separation, which was demonstrated by POM, DSC and WXRD. Finally, hexamethylene tetramine was used to cure the novolac blends to form hybrid network phenolic nanocomposites. Dynamic mechanical analysis results showed that the storage modulus of the hybrid networks was improved up to 20 wt% POSS loading; the T _g was increased with increasing POSS content and higher than that of the control phenolic resin except that 5 wt% POSS loading. Thermo gravimetric analysis showed that the thermal stability of hybrid networks was also enhanced with the incorporation of POSS.     

Role of copper alumina nanoparticles on the performance of polyvinylchloride nanocomposites

Poly(vinyl chloride) (PVC) nanocomposites with different contents of copper alumina (Cu-Al₂O₃) nanoparticles were prepared by the solution casting method. The effects of the nanoparticles on structural, thermal, electrical, contact angle and mechanical properties were thoroughly examined. The presence of Cu-Al₂O₃ in the macromolecular chain was confirmed through Fourier transform infrared (FTIR) spectroscopy. The X-ray diffraction (XRD) analysis of PVC nanocomposites showed the systematic arrangement of Cu-Al₂O₃ nanoparticles within the polymer, which indicated the higher crystallinity of the nanocomposites. The surface morphology of PVC was changed into hemispherical shaped particles by the inclusion of nanofiller was analyzed from SEM images. The glass transition temperature of the nanocomposites obtained from differential scanning calorimetry (DSC) was found to be increased with an increase in loading of nanoparticles in the polymer. The AC conductivity and dielectric studies revealed that the inclusion of nanofiller increases the electrical properties of the material and the composite with 7 wt.% sample showed the maximum conductivity and dielectric constant. The mechanical properties such as modulus, tensile strength, hardness, and impact properties of the PVC nanocomposites were significantly enhanced by the reinforcement of nanoparticles into the PVC matrix. The reinforcing mechanism behind the increase in tensile strength with the addition of nanoparticles was correlated with different theoretical models. The highest mechanical and electrical properties were observed for 7 wt.% Cu-Al₂O₃ loaded nanocomposite. Contact angle measurements of PVC with various loadings of Cu-Al₂O₃ nanofillers demonstrated that the nanoparticle attachment increased the hydrophobicity of the polymer matrix.     

Crystallinity of biodegradable polymers reinforced with functionalized carbon nanotubes

Well-dispersed multiwall carbon nanotubes (MWCNTs) were prepared by grafting poly(L-lactide-co-ε-caprolactone) (PLACL) biodegradable copolymer onto the sidewall of hydroxylated MWCNTs using oligomeric L-lactide (LA) and ε-caprolactone (CL). After preparation of MWCNT/PLACL composites, the effect of functionalized MWCNTs on crystallinity of PLACL was investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and polarized light optical microscopy (POM). The surface functionalization effectively improved the dispersion and adhesion of MWCNTs which acted as reinforcing filler in the PLACL polymer matrix and hence improved the physical and thermomechanical properties of the nanocomposites. The glass transition temperature (T _g) and the crystallinity of nanocomposites decreased in comparison with those of neat PLACL when the concentration of functionalized MWCNTs in nanocomposites was 0.5 wt%. With further increment in concentration of functionalized MWCNTs, the T _g of composites increased until the T _g of neat PLACL, and also the crystallinity of composites increased. The functionalized MWCNTs have no significant effect on the melting point of nanocomposites. The MWCNTs acted as heterogeneous nucleation points and increased the lamella size and therefore the crystallinity of PLACL. Furthermore, the larger agglomerated clusters of both kinds of MWCNTs (i.e., MWCNT-grafted-PLACL and pristine MWCNTs) are more effective than small clusters as nucleation points for growing the spherulites.     

Preparation,characterization, and dynamic adsorption–desorption studies on polypyrrole encapsulated TiO2 nanoparticles

Binary doped polypyrrole (PPy) encapsulated Titania (TiO₂) nanoparticles were prepared by oxidative polymerization using FeCl₃ as oxidant in presence of camphorsulfonic acid (CSA) as surfactant. Both FeCl₃ (oxidant) and camphorsulfonic acid (surfactant) also act as dopant and hence thus prepared polypyrrole/Titania (TiO₂@PPy) is termed as binary doped nanocomposite i.e. FeCl₃ dopes polypyrrole by oxidation mechanism while camphorsulfonic acid dopes polypyrrole by protonic doping mechanism. The TiO₂@PPy coreshell nanocomposites were characterized by Fourier transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD), thermogravimetry, differential scanning calorimetry (DSC), field emission‐scanning electron microscopy (FE‐SEM), and inductance‐capacitance‐resistance (LCR) measurements. The results indicated that the structural and electrical properties of the TiO₂@PPy coreshell nanocomposites were significantly influenced by the extent of TiO₂ nanoparticles loading of polypyrrole. The direct current (DC) electrical conductivity of the as‐prepared TiO₂@PPy coreshell nanocomposites was higher than that of PPy. As‐prepared TiO₂@PPy coreshell nanocomposites were also studied for their dielectric losses for alternating current (AC) which is useful characteristic for their application in the fabrication of charge storing devices. TiO₂@PPy coreshell nanocomposites showed synergistic effect of combining components in improving their alcohol sensing properties. This improvement may be attributed to the adsorption on and desorption from alcohols TiO₂@PPy interface of the nanocomposites and alcohol vapors causing decrease in depletion region. The TiO₂@PPy coreshell nanocomposites were observed to show better reproducibility of electrical conductivity and fast self‐recovery during the alcohol vapor sensing process. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43411.     

Characterization,conductivity studies,dielectric properties,and gas sensing performance of in situ polymerized polyindole/copper alumina nanocomposites

Conducting polymer composites of polyindole (PIN) and copper–alumina (Cu–Al₂O₃) nanocomposites were synthesized by in situ polymerization of indole with different contents of Cu–Al₂O₃ nanoparticles. The polymer nanocomposites were characterized by Fourier transform infrared (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), transmission electron microscope (TEM), differential scanning calorimetry, thermogravimetric analysis, and ammonia gas sensing performance was also analyzed. FTIR and XRD studies revealed the attachment of Cu–Al₂O₃ in the molecular chain of PIN. The presence of bright trapezoid channels and variation in morphology for different loading of nanoparticles were confirmed by SEM and TEM. The attachment of Cu–Al₂O₃ nanoparticles in the PIN matrix was confirmed through EDX spectroscopy. The glass transition temperature and thermal stability of the composites were greatly enhanced with the loading of Cu–Al₂O₃. Enhancement in alternating current conductivity, dielectric constant and the current–voltage characteristics of the prepared composite revealed the semiconducting nature of the system with an increase in the loading of nanoparticles. Also, nanocomposite exhibited an excellent sensitivity and fast response to ammonia gas. The evaluated result of the present study suggested that Cu–Al₂O₃ reinforced PIN hybrid is a good candidate for the fabrication of electrochemical devices.     

CO2 sorption and diffusion in polymethyl methacrylate–clay nanocomposites

This study reports the glass transition temperature (T_g), and sorption and diffusion of subcritical CO₂ gas in polymethyl methacrylate (PMMA) nanocomposites containing organically modified smectite clay, Cloisite 20A (C20A). A range of methods for preparing the PMMA‐clay nanocomposites was investigated and a solution coprecipitation method was selected as the most appropriate. Using this method, PMMA nanocomposite containing 2, 4, 6, and 10 wt% nanoclay loadings were prepared. Wide‐angle X‐ray diffraction (XRD) analysis and scanning electron microscopy (SEM) indicated that the 2 wt% nanocomposite materials had a well‐dispersed intercalated clay structure. The T_g for PMMA‐C20A nanocomposites, as measured by differential scanning calorimetry (DSC), was found to be independent of the clay loading. CO₂ solubility studies from 0 to 65°C and pressures up to 5.5 MPa using an in situ gravimetric technique were performed on compression‐molded films. The organoclay was found to have no effect on the solubility of CO₂ in PMMA, and therefore the solubility of CO₂ in the nanocomposite can be determined from the solubility of CO₂ in the matrix polymer alone. Diffusion coefficients were determined using the appropriate transport models for these test conditions and the diffusion coefficients for CO₂ in PMMA‐C20A composites were found to increase with organoclay loading. It is believed that the processing path taken to prepare the nanocomposites may have resulted in the agglomeration of the C20A organoclay, thereby preventing the polymer chains from fully wetting and intercalating a large number of clay particles. These agglomerations are responsible for the formation of large‐scale holes within the glassy nanocomposite, which behave as low resistance pathways for gas transport within the PMMA matrix. POLYM. ENG. SCI., 45:904–914, 2005. © 2005 Society of Plastics Engineers     

Preparation,Characterization and Properties of Poly(vinyl chloride)/CaSO4 Nanocomposites

Poly(vinyl chloride)/CaSO₄ nanocomposites were prepared on Brabender plasticorder. Moreover, for comparison PVC/ commercial CaSO₄ composites was prepared. The amount of loadings of nano CaSO₄ and commercial CaSO₄ was in the range of 0–12 wt%. Nano CaSO₄ was synthesized by matrix-mediated growth technique. The size and shape of nano CaSO₄ were characterized by X-ray diffraction (XRD) and transmission electron microscope (TEM). These PVC nanocomposites were then subjected to mechanical, thermal analysis on UTM, and TGA respectively. Morphology studies of PVC nanocomposites were done on scanning electron microscope (SEM). The morphology study showed that nano CaSO₄ get exfoliated and intercalated with the PVC matrix. Notched Charpy impact strengths of PVC nanocomposites was drastically improved compared to that of pristine PVC and commercial CaSO₄ composites. PVC/CaSO₄ nanocomposites showed higher values of tensile strength, elongation at break and impact strength than PVC/CaSO₄ (commercial) composites. Impact strengths also gives some drastic dependence on nano CaSO₄ content and give a maximum value at certain CaSO₄ loadings.     

Electrical properties and thermal degradation of poly(vinyl chloride)/polyvinylidene fluoride/ZnO polymer nanocomposites

In this work, polymer nanocomposites consisting of a poly(vinyl chloride) (PVC) and polyvinylidene fluoride (PVDF) polymer network with ZnO nanoparticles as a dopant were prepared by solution casting. An XRD study of the PVC/PVDF/ZnO polymer nanocomposites shows predominantly sharp and high intensity peaks. However, the intensity and sharpness of the XRD peaks decreases with further increment in loading of ZnO (wt%), which reveals a proper intercalation of ZnO nanoparticles within the PVC/PVDF polymer system. Fourier transform infrared spectroscopy has been used to verify the chemical compositional change as a function of ZnO nanoparticle loading. TGA analysis clearly describes the thermal degradation of the pure polymer and polymer nanocomposites. The complex dielectric function, AC electrical conductivity and impedance spectra of these nanocomposites were investigated over the frequency range from 10 Hz to 35 MHz. These spectra were studied with respect to the Wagner ? Maxwell ? Sillars phenomenon in the low frequency region. Nyquist plots of the PVC/PVDF/ZnO nanocomposites were established from impedance measurements. The temperature‐dependent DC ionic conductivity obtained from the Nyquist plots follows Arrhenius behaviour. © 2016 Society of Chemical Industry     

Electrolytic admicellar polymerization of pyrrole on natural rubber/clay nanocomposites

Organic–inorganic composites consisting of natural rubber (NR), polypyrrole (PPy), and sodium montmorillonite (Na‐MMT) were synthesized via electrolytic admicellar polymerization. A constant potential of 9 volts was chosen for the synthesis. The PPy concentration was fixed at 100 mM, and the clay contents were varied from 1 to 7 parts per hundred of rubber (phr). The synthesized nanocomposites were characterized by Fourier transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD), scanning electron microscopy, and transmission electron microscopy (TEM), together with thermal stability (TGA), mechanical properties, and electrical conductivity (σ_dc) studies. The FTIR spectra indicated the characteristic peaks of both PPy and MMT clay and also evidenced a slight interaction between the PPy chain and the clay layers, verifying the success of electrolytic admicellar polymerization. XRD and TEM results pointed out the good dispersion of clay platelets in the polymer matrix, suggesting an exfoliated structure. The morphology of the nanocomposites was greatly dependent on the amount of MMT clay, especially at a 7 phr loading. The initial modulus and tensile strength of the nanocomposites containing the 7 phr loading were about four and two times higher, compared with unfilled NR/PPy, respectively. Thermal stability studies revealed a slight improvement in the decomposition temperature for the PPy component by the clay layers, whereas the opposite trend was found for the NR component. More interestingly, the electrical conductivity of the admicelled rubber increased significantly (～ 19–32 times) with increasing clay contents from 1 to 7 phr, in comparison with unfilled NR/PPy. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis and characterization of polyacrylamide‐calcium carbonate and polyacrylamide‐calcium sulfate nanocomposites

Polyacrylamide‐calcium carbonate (PAM/CaCO₃) and polyacrylamide‐calcium sulfate (PAM/CaSO₄) nanocomposites were prepared via solution‐mixing technique. The resulting PAM‐based nanocomposites with various CaCO₃ and CaSO₄ nanoparticles contents (0–4% w/w) were investigated. Nanoparticles of CaCO₃ and CaSO₄ were synthesized by in situ deposition technique. In this technique, the surface modification of nanoparticles was performed by nonionic polymeric surfactant. The particle size of nanoparticles was recognized by X‐ray diffraction and scanning electron microscope (SEM) analysis which confirms that the particle has diameter of 25–33 nm. As prepared, nanocomposites films (thickness, 40‐μm) were characterized by Fourier transform infrared (FT‐IR), SEM, and energy‐dispersive X‐ray spectroscopy (EDS). FT‐IR shows the chemical structure of nanocomposites where as SEM analysis suggested that the nanofillers dispersed well in polymer matrix and EDS shows the elemental composition of the nanocomposite samples. Thermal properties of the nanocomposites were studied by using differential scanning calorimetric analysis. The PAM/CaCO₃ and PAM/CaSO₄ nanocomposites showed a higher glass transition temperature and a better thermal stability compared to the pure PAM. The glass transition temperature (T_g) of nanocomposites increases with increase in content of nanoparticles. It may be owing to the interaction between inorganic and organic components. POLYM. COMPOS.,, 2012. © 2012 Society of Plastics Engineers     

Determination of the glass transition temperature of polymer/layered silicate nanocomposites from positron annihilation lifetime measurements

The glass transitions of acrylonitrile-butadiene rubber (NBR)/organoclay nanocomposites with various silicate contents were investigated using positron annihilation lifetime spectroscopy (PALS). The nanocomposites were prepared through melt intercalation of NBR with various concentrations of organoclay (OC30B) modified with the organic modifier, methyl tallow bis(2-hydroxyethyl) quaternary ammonium (MT2EtOH), i.e., Cloisite^® 30B. X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HR-TEM) measurements of the NBR/OC30B nanocomposites showed that the NBR chains were intercalated between the silicate layers, thereby increasing the gallery heights of the organosilicates. The glass transition temperature of NBR was determined using differential scanning calorimetry (DSC). However, it seemed to be very difficult to clearly resolve the very small differences in T_gs caused from various loading of nanosized silicate in NBR/OC30B nanocomposites. Hence, we performed positron annihilation lifetime spectroscopy (PALS) on NBR/OC30B nanocomposites containing various amounts of OC30B (1-10 wt%). Significant changes in the temperature dependencies of free volume parameters (i.e., lifetimes and intensities) were observed at the transition temperature, T_g,PALS, and the T_g,PALS values were found to increase with increasing organoclay content in the samples. These observations are consistent with PALS having a higher sensitivity in the detection of very small changes in free volume properties. The present findings thus highlight the usefulness of PALS for studying phase transition phenomena in polymeric materials with nanoscale structural variations.     

Structural,thermal and dielectric properties of 2D layered Ti3C2Tx (MXene) filled poly (ethylene-co-methyl acrylate) (EMA) nanocomposites

Light-weight and flexible 2D MXene-based polymer materials with low dielectric loss and high dielectric constant have drawn great attention in the power systems and modern electronic field. A series of Ti₃C₂T_x/EMA composites were fabricated via simple solution casting followed by a compression molding method with various mass concentrations of Ti₃C₂T_x (0, 1, 3, 5, 8, 10, 12, and 15 wt%). Morphological and micro structural properties of the prepared composites were studied via X-ray diffraction (XRD) and field-emission scanning electron microscope (FESEM), where the distribution of Ti₃C₂T_x in the Ti₃C₂T_x/EMA composites was confirmed. Thermal behaviors were analyzed by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) investigations. The DSC analysis reveals that the % of crystallinity decreases from 11.06 with 1 wt% to 5.68 with 15 wt%, where Ti₃C₂T_x acts as an efficient nucleating agent. TGA data confirm the enhancement of the thermal stability of the composites upon increasing in Ti₃C₂T_x loading. The room temperature electrical and dielectric behavior of the studied composites were examined in the frequency range of 100 Hz–5 MHz. In this work, the 10 wt% of Ti₃C₂T_x loaded poly (ethylene-co-methyl acrylate) composite (EMA) showed higher dielectric permittivity (ε′ = 124.22) with lower dissipation loss (tan δ = 0.051) at 100 Hz among all weight percentages. The behavior of charge carriers in the prepared composites was studied by utilizing the impedance spectroscopy technique. The electrical parameters were calculated from the fitted Nyquist plots with a corresponding circuit model. I–V curves confirmed the conduction mechanisms of the composites. This beneficial enhancement in electrical properties recommends the composite can be utilized in flexible electronic storage devices.     

Study on glass transition temperature and mechanical properties of cadmium sulfide/polystyrene nanocomposites

The cadmium sulfide/polystyrene (CdS/PS) nanocomposites with concentration (0, 2, 4, 6, and 8) wt% of CdS nanoparticles were prepared by solution casting method and characterized through fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM) measurements. The particle size of nanoparticles is found to be around 15 nm. Glass transition and mechanical behavior of CdS/PS nanocomposites were investigated using dynamic mechanical analyzer (DMA). The mechanical properties such as Young's modulus and tensile strength were determined at room, as well as at elevated temperatures through their stress–strain curves. The result shows that glass transition temperature (T_g) is shifted toward the higher temperature after the addition of CdS nanoparticles. The mechanical properties increased at low wt% loading of CdS nanoparticles and decreased for higher wt% loading of CdS nanoparticles. It was also found that mechanical properties decline with increase in the temperature. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers     

Polyurethane/amino‐grafted multiwalled carbon nanotube nanocomposites: Microstructure,thermal, mechanical,and rheological properties

A mixture of two different polyols, (polytetramethylene ether glycol and polydimethylsiloxane), were employed to synthesize a new structure of polyurethane (PU) with methylene diphenyl diisocyanate (MDI) and 1,4‐butanediol as chain extender. PU nanocomposites containing variable amount (0.3, 0.5, 1, and 3 wt %) of amino‐grafted multiwalled carbon nanotubes (NH₂‐MWNT) were prepared via in situ polymerization. The dispersion of NH₂‐MWNT into polymer matrix was investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Fourier transform infrared spectroscopy (FT‐IR) confirmed the urethane‐urea chemical bonding between the PU chains and the NH₂‐MWNT. Thermal stabilities of the nanocomposites were examined with thermogravimetric analysis (TGA) and the results indicated a remarkable improvement with increasing NH₂‐MWNT contents. The results of dynamic mechanical thermal analysis (DMTA) including storage modulus (E′) and glass transition temperature (T_g), as well as tensile properties demonstrated that the yield strength, strain‐at‐break, and young modulus were enhanced by increasing NH₂‐MWNT content. Rheological behavior including complex viscosity and storage and loss moduli of the PU nanocomposites improved with increasing NH₂‐MWNT loading, as well. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44411.     

Influence of Processing Conditions on the Properties of Polystyrene (PS)/organomontmorillonite (OMMT) Nanocomposites Prepared via Solvent Blending Method

A series of polystyrene (PS)/organomontmorillonite (OMMT) clay nanocomposites was prepared by effectively dispersing the inorganic nanolayers of OMMT clay in the organic PS matrix via the solvent blending method using xylene as a solvent. The resulting samples were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The XRD and TEM results show that the intercalation/exfoliation of OMMT can be divided into solvent swelling and layer breaking processes and is affected by several reaction parameters such as nanofiller loading, refluxing temperature, and refluxing time. TGA data show that the PS/OMMT nanocomposites have significant enhanced thermal stability. When 50% weight loss is selected as a point of comparison, the thermal decomposition temperature of PS/OMMT nanocomposite with 7 wt% of OMMT is 15°C higher than that of pure PS. The glass transition temperature (T_g) of PS/OMMT nanocomposites is about 5.0–6.2°C higher than that of pure PS. The water uptake capacity of PS/OMMT nanocomposites is negligible when compared with pure PS.