Study of polyarylene ether nitrile terminated with phthalonitrile/hybrid Fe3O4 nanospheres composites by orthogonal experiments

A novel series of composites of polyarylene ether nitrile terminated with phthalonitrile (PEN‐t‐Ph) filled with hybrid Fe3O4 nanospheres (h‐Fe₃O₄) was prepared via in situ composition. Based on the cross‐linking interactions between the phthalonitrile at the end of PEN‐t‐Ph molecular chains and the phthalonitrile on the surface of h‐Fe₃O₄ particles to form phthalocyanine ring, it was shown that the PEN‐t‐Ph/h‐Fe₃O₄ system had superior interfacial compatibility and the h‐Fe₃O₄ particles were locked in the matrix resin. These results had been confirmed by scanning electron microscope analysis. By orthogonal experiments and statistic analysis, the optimal conditions of cure temperature, type of h‐Fe₃O₄ and content of h‐Fe₃O₄ had been determined. Meanwhile, the results of range analysis and variance analysis indicated that the cure temperature had great effects on the thermal properties. Thermal studies revealed that the glass transition temperature of PEN‐t‐Ph/h‐Fe₃O₄ cured at 320°C was 214.7°C, increased by about 40°C compared to the PEN‐t‐Ph/h‐Fe₃O₄ without heat treatment, and the temperature corresponding to the weight loss of 5 wt % was increased by about 20°C. Mechanical measurements indicated that PEN‐t‐Ph/h‐Fe₃O₄ cured at 320°C possesses excellent mechanical properties with tensile strength of 93.33 MPa and tensile modulus of 2414.05 MPa, 9.91 MPa, 355.76 MPa higher than pure PEN‐t‐Ph film cured at 320°C, and 13.26 MPa, 397.90 MPa higher than PEN‐t‐Ph/h‐Fe₃O₄ without heat treatment. Most importantly, the presence of h‐Fe₃O₄ particles endows PEN‐t‐Ph/h‐Fe₃O₄ system with good magnetic property. Thus, PEN‐t‐Ph/h‐Fe₃O₄ cured at 320°C may have potential applications in field of magnetic materials. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40418.     

Effect of surface functionalization on the properties (rheological,mechanical, and dielectric) and microtopography of PEN/CPEN‐f‐CNTs nanocomposites

Novel carboxylic poly(arylene ether nitrile)s (CPEN) functionalized carbon nanotubes (CPEN‐f‐CNTs) were successfully prepared by a simple and effective solvent–thermal route. The CPEN‐f‐CNTs were subsequently used as the novel filler for preparation of high performance poly(arylene ether nitrile)s (PEN) nanocomposites. The SEM characterization of the PEN nanocomposites revealed that the CPEN‐f‐CNTs present better dispersion and interfacial compatibility in the PEN matrix, which was confirmed by the linear rheological analysis (Cole–Cole plots) as well. Consequently, the improved thermal stability (increased initial and maximum decomposition temperature) and enhanced mechanical properties (tensile strength and modulus) were obtained from nanocomposites using CPEN‐f‐CNTs. More importantly, the PEN/CPEN‐f‐CNTs nanocomposites not only show a high dielectric constant but also have low dielectric loss. For example, a dielectric constant of 39.7 and a dielectric loss of 0.076 were observed in the PEN composite with 5 wt% CPEN‐f‐CNTs loading at 100 Hz. Therefore, the flexible PEN/CPEN‐f‐CNTs nanocomposites with outstanding mechanical, thermal and dielectric properties will find wide application in the high energy density capacitors. POLYM. COMPOS., 37:2622–2631, 2016. © 2015 Society of Plastics Engineers     

Enhanced properties of phthalonitrile‐terminated polyarylene ether nitriles embedded with hybrid MWCNT–boehmite nanocomposites

The main motivation of the present work was to fabricate novel multifunctional polymer‐based nanocomposites. The nanocomposites embedded with multi‐walled carbon nanotube‐boehmite (MWCNT‐boehmite) were prepared via hot pressure casting technique. The MWCNT coated with boehmite were synthesized by hydrothermal synthesis. Subsequently, as‐prepared MWCNT‐boehmite was added into the phthalonitrile‐terminated polyarylene ether nitriles (PEN‐t‐CN) matrix in order to benefit from the synergetic effect of MWCNT and boehmite. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) X‐ray diffraction (XRD), and Fourier transform infrared (FTIR) were employed to confirm the existence of MWCNT‐boehmite in our article. Furthermore, the structures, fracture morphologies, thermal, mechanical and dielectric properties of the nanocomposites were investigated, respectively. SEM images indicated that the MWCNT‐boehmite was homogeneously dispersed in the polymer, which acted as an essential factor to ensure good physical properties. The TGA analysis showed that the incorporation of MWCNT‐boehmite enhanced the thermal stability of the nanocomposites with initial degradation temperature (T_id) increasing from 458 to 492°C, while that of the pure PEN‐t‐CN was 439°C. The mechanical testing proved that significant enhancement of mechanical properties has been achieved. The tensile strength of PEN‐t‐CN/MWCNT‐boehmite composites with 3 wt% MWCNT‐boehmite reached the maximum (78.33 MPa), with a 41.7 % increase compared to the pure polymer. More importantly, the unique dielectric properties were systematically discussed and the results demonstrated that dielectric properties exhibited little dependency on frequency. For the incorporation of hybrid filler, the positive impact of MWCNT‐boehmite hybrid material resulted in polymer‐based nanocomposites with enhanced physical properties. POLYM. COMPOS., 36:2193–2202, 2015. © 2014 Society of Plastics Engineers     

Effects of ball milling dispersion of nano‐SiOx particles on impact strength and crystallization behavior of nano‐SiOx–poly(phenylene sulfide) nanocomposites

Ball milling and mixing with strong shear force and strike force were applied to get fine dispersion of nano‐SiO_x particles in poly(phenylene sulfide) (PPS) powder. Nano‐SiO_x/PPS composites were manufactured by intensive compounding with 3 wt% nano‐SiO_x particles. Effects of the ball milling dispersion on crystal behavior and impact strength of nano‐SiO_x/PPS nanocomposites were studied. Physical mechanisms of ball milling dispersion were investigated. Evaluations based on both WAXD and DSC indicates that crystallization behavior of nano‐SiO_x/heat‐treated PPS (HT‐PPS) nanocomposites was influenced by the ball milling process. Their crystallinity was 25% less while Izod impact strength was 89% better than those of as‐received neat PPS. Increased kinetic energy via ball milling by external work makes nano‐SiO_x able to overcome the attraction from itself to prevent agglomeration. Interfacial bonding of two phases between nano‐SiO_x and PPS was enhanced by crosslinking in HT‐PPS and reduction in surface tension of interface during ball milling. The bonds allow SiO_x to dissipate energy and thus improve PPS impact strength from the addition of nano‐SiO_x. POLYM. ENG. SCI., 46:820–825, 2006. © 2006 Society of Plastics Engineers     

Comprehensive high‐performance epoxy nanocomposites co‐reinforced by organo‐montmorillonite and nano‐SiO2

Comprehensive high‐performance epoxy nanocomposites were successfully prepared by co‐incorporating organo‐montmorillonite (o‐MMT) and nano‐SiO₂ into epoxy matrix. Because of the strong interaction between nanoscale particles, the MMT layers were highly exfoliated, and the exfoliated nanoscale MMT monoplatelets took an interlacing arrangement with the nano‐SiO₂ particles in the epoxy matrix, as evidenced by X‐ray diffraction measurement and transmission electron microscopy inspection. Mechanical tests and thermal analyses showed that the resulting epoxy/o‐MMT/nano‐SiO₂ nanocomposites improved substantially over pure epoxy and epoxy/o‐MMT nanocomposites in tensile modulus, tensile strength, flexural modulus, flexural strength, notch impact strength, glass transition temperature, and thermal decomposition temperature. This study suggests that co‐incorporating two properly selected nanoscale particles into polymer is one pathway to success in preparing comprehensive high‐performance polymer nanocomposites. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Effects of graphene nanosheets on the dielectric,mechanical, thermal properties,and rheological behaviors of poly(arylene ether nitriles)

Poly(arylene ether nitriles) (PEN) containing various contents of graphene nanosheets (GNs) was prepared via solution‐casting method and investigated for their dielectric, mechanical, thermal, and rheological properties. For PEN/GNs nanocomposite with 5 wt % GNs, the dielectric constant was increased to 9.0 compared with that of neat PEN (3.1) and dielectric losses of all nanocomposites were in the range of 0.019–0.023 at 1 kHz. The tensile modulus and strength were increased about 6 and 14% with 0.5% GNs, respectively. The fracture surfaces of the all PEN/GNs nanocomposites revealed that GNs had good adhesion to PEN matrix. The thermal properties of the nanocomposites showed significant increase with increasing GN loading. For 5 wt % GNs‐reinforced PEN nanocomposite, the temperatures corresponding to a weight loss of 5 wt % (T_d5%) and 30 wt % (T_d30%) increased by about 20 and 13°C, respectively. Rheological properties of the PEN nanocomposites showed a sudden change with the GN fraction and the percolation threshold was about 1 wt % of GNs. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Effect of nitrile functionalized graphene on the properties of poly(arylene ether nitrile) nanocomposites

In this study, novel nitrile functionalized graphene (GN‐nitrile)/poly(arylene ether nitrile) (PEN) nanocomposites were prepared by an easy solution‐casting method and investigated for the effect of surface modification on the dielectric, mechanical and thermal properties. Graphene (GN) was first functionalized by introduction of nitrile groups onto the GN plane, which was confirmed by scanning electron microscopy, differential scanning calorimetry, Fourier transform infrared spectroscopy, thermogravimetric analysis and dispersibility research. Compared with pure GN, the grafted nitrile groups on the GN‐nitrile can interact with nitrile groups in PEN and lead to flat but better dispersion and stronger adhesion in/to the PEN matrix. Consequently, GN‐nitrile had a more significant enhancement effect on the properties of PEN. The dielectric constant of the PEN/GN‐nitrile nanocomposite with 5 wt% GN‐nitrile reaches 11.5 at 100 Hz, which is much larger than that of the pure PEN matrix (3.1). Meanwhile, dielectric loss is quite small and stable and the dielectric properties showed little frequency dependence. For 5 wt% GN‐nitrile reinforced PEN composites, increases of 17.6% in tensile strength, 26.4% in tensile modulus and 21 °C in T_d5% were obtained. All PEN/GN‐nitrile nanocomposite films can stand high temperature, up to 480 °C. Hence, novel dielectric PEN/GN‐nitrile nanocomposite films with excellent mechanical and thermal properties can be used as dielectric materials under some critical circumstances such as high wear and temperature. Copyright © 2012 Society of Chemical Industry     

Nano‐sio2‐reinforced ultraviolet‐curing materials for three‐dimensional printing

As an additive manufacturing technology, ultraviolet (UV)‐curing three‐dimensional printing, which requires the use of a photocurable resin, is increasingly being used to produce customized end‐user parts of many complex shapes. In this study, to improve the strength and ductility of printing materials, nano‐SiO₂‐reinforced photocurable resins were prepared by a planetary ball mill; then, the morphology, photochemistry, thermal property, and mechanical properties of the nanocomposites were investigated and characterized. Transmission electron microscopy analysis indicated that the modified nano‐SiO₂ was well dispersed in the photocurable resin. The glass‐transition temperature increased from 67.2°C for the unfilled resin to 71.7 and 80.1°C for nanocomposites with nano‐SiO₂ contents of 0.3 and 0.7 wt %, respectively. The tensile strength and impact strength were increased by 46.7 and 165.3% for nanocomposites with 0.3 wt % nano‐SiO₂. The flexural modulus of the nanocomposites increased from 1.7 to 8.0 GPa when 0.7 wt % nano‐SiO₂ was added to the photocurable resin; this appeared to originate from the relatively high level of dispersion and the intimate combination of the nano‐SiO₂ with the matrix. The investigation of the physical and chemical properties of such UV‐curing materials showed that the low filler concentration (<1 wt %) of nano‐SiO₂ did not affect the processability of the nanocomposites. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42307.     

Influence of incorporation sequence of silica nanoparticles on morphology,crystallization behavior,mechanical properties,and thermal resistance of melt blended thermoplastic natural rubber

Thermoplastic natural rubber nanocomposites based on epoxidized natural rubber (ENR) and polypropylene blends at a fixed blend ratio of 50/50 wt% reinforced with small amount (2.5 wt%) of nanosilica (SiO₂) were prepared by melt‐mixing through three different incorporation sequences in an internal mixer. The effects of incorporation techniques on morphology, crystallization behavior, mechanical properties, dynamic, rheological characteristics, and thermal resistance of thermoplastic natural rubber (TPNR) nanocomposites were investigated. It was found that the dispersion of nanosilica in TPNRs was significantly dependent on the incorporation sequence. In the case where SiO₂ was premixed in ENR before blending with polypropylene (PP), the final morphology showed the good dispersion of SiO₂ in ENR phase, while the SiO₂ particles were localized near the PP interface when SiO₂ was premixed the in PP first. Whereas, when the three components were simultaneously mixed, the SiO₂ particles were mainly dispersed in the PP phase. It was also found that the improvements of Young's modulus, tensile strength, damping behavior, and thermal stability of TPNR nanocomposites were more pronounced when the SiO₂ particles localized in ENR phase. By contrast, the presence of SiO₂ particles in PP domain either near the interface or inside the PP phase affected the reduction in crystallinity of PP phase and showed a negative effect on mechanical properties due to the poor interface interaction between PP and SiO₂ particles. POLYM. COMPOS., 33:1911–1920, 2012. © 2012 Society of Plastics Engineers     

Investigation on the mechanical performances of ternary nylon 6/SEBS elastomer/nano‐SiO2 hybrid composites with controlled morphology

The distribution of maleated styrene‐hydrogenated butadiene‐styrene (mSEBS) elastomer and nano‐SiO₂ in nylon 6 matrix was controlled by varying the blending procedure. Nano‐SiO₂ particles with different surface properties (hydrophilic versus hydrophobic) were adopted to adjust their interactions with other components. Two different structures, separate dispersion of nano‐SiO₂ and elastomer particles as well as encapsulation of nano‐SiO₂ fillers by the elastomer, were obtained. The structures were confirmed through scanning electron microscope (SEM) investigation. The mechanical measurement results showed that the microstructure and the interactions among the components had dramatic influences on the final mechanical properties, especially Izod fracture toughness, for the ternary nanocomposites. The nanocomposites containing hydrophilic nano‐SiO₂ had better mechanical performances compared with the composites filled with hydrophobic SiO₂ when they were in the same microstructure. The nanocomposites with separate dispersion structure showed higher stiffness compared with those of encapsulation type. However, the separately dispersed nano‐SiO₂ particles restricted the cavitation of elastomer phases that led to low toughening effectiveness. The difference of cavitation intensity for elastomer phase was revealed by SEM investigation on the facture surfaces for the nanocomposites with the two different microstructures. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Preparation,characterization, and properties of TiO2/PLA nanocomposites by in situ polymerization

In situ polymerization method was used to prepare TiO₂/polylactide (PLA) nanocomposites with different contents of TiO₂ in this work. The size of the organically modified TiO₂ particles was investigated by X‐ray diffraction (XRD) analysis. Scanning electron microscope (SEM) shows that nano‐TiO₂ particles disperse in the PLA evenly when the content of TiO₂ is low (less than 3 wt%). The differential scanning calorimeter (DSC), thermogravimetry analysis (TGA), and tensile test were used to study the thermal and mechanical properties of the composites. Results show that both the thermal and mechanical properties are markedly improved when the content of TiO₂ is 3 wt%. UV light irradiation and solution degradation experiment show that degradation of the composites is higher when the content of TiO₂ increases and due to the introduction of TiO₂ particles in the nanocomposites, the TiO₂/PLA nanocomposites exhibit remarkable bacteriostasic activity. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

Study of surface‐functionalized nano‐SiO2/polybenzoxazine composites

A series of the surface‐functionalized nano‐SiO₂/polybenzoxazine (PBOZ) composites was produced, and an attempt was made to improve the toughness of PBOZ material, without sacrificing other mechanical and thermal properties. A benzoxazine functional silane coupling agent was synthesized to modify the surface of nano‐SiO₂ particles, which were then mixed with benzoxazine monomers to produce the nano‐SiO₂‐PBOZ nanocomposites. The notched impact strength and the bending strength of the nano‐SiO₂‐PBOZ nanocomposites increase 40% and 50%, respectively, only with the addition of 3 wt % nano‐SiO₂. At the same load of nano‐SiO₂, the nano‐SiO₂‐PBOZ nanocomposites exhibit the highest storage modulus and glass‐transition temperature by dynamic viscoelastic analysis. Moreover, the thermal stability of the SiO₂/PBOZ nanocomposites was enhanced, as explored by the thermogravimetric analysis. The 5% weight loss temperatures increased with the nano‐SiO₂ content and were from 368°C (of the neat PBOZ) to 379°C or 405°C (of the neat PBOZ) to 426°C in air or nitrogen with additional 3 wt % nano‐SiO₂. The weight residue of the same nanocomposite was as high as 50% in nitrogen at 800°C. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Preparation and characterization of chitosan/α‐zirconium phosphate nanocomposite films

Nano‐fillers play an important role in the final structure and properties of nanocomposites. The objective of the work presented here was to prepare nanocomposite films of chitosan/α‐zirconium phosphate using a casting process, with α‐zirconium phosphate (α‐ZrP) as nano‐filler and chitosan as matrix. The effects of α‐ZrP on the structure and properties of the nanocomposites were investigated. X‐ray diffraction patterns showed that α‐ZrP crystals were intercalated by n‐butylamine. The results from scanning electron microscopy and transmission electron microscopy indicated that α‐ZrP could be uniformly dispersed in the chitosan matrix when α‐ZrP loading in the composites was less than 2 wt%. A strong interaction between α‐ZrP and chitosan formed during the film‐forming process. Tensile testing showed that the tensile strength and elongation at break of nanocomposite films achieved maximum values of 61.6 MPa and 58.1%, respectively, when α‐ZrP loading was 2 wt%. The parameter B calculated from tensile yield stress according to the Pukanszky model was used to estimate the interfacial interaction between the chitosan matrix and α‐ZrP. Films with a loading of 2 wt% α‐ZrP had the highest B value (3.2), indicating the strongest interfacial interaction. The moisture uptake of the nanocomposites was reduced with addition of α‐ZrP. It can be concluded that α‐ZrP as nano‐filler in a chitosan matrix can enhance the mechanical properties of nanocomposites due to the strong interactions between α‐ZrP and chitosan. Copyright © 2010 Society of Chemical Industry     

Synergistic enhancement of mechanical,crystalline and dielectric properties of polyarylene ether nitrile‐based nanocomposites by unidirectional hot stretching–quenching

Copper tetra‐amine phthalocyanine (NH₂‐CuPc) was grafted onto barium titanate (BaTiO₃) whose surface was modified by carboxylic polyarylene ether nitrile (CPEN) to afford a nano‐filler (CPEN‐f‐BaTiO₃@NH₂‐CuPc). Through a solution‐casting method combined with ultrasonic dispersion technology, the obtained CPEN‐f‐BaTiO₃@NH₂‐CuPc was successfully incorporated into biphenyl polyarylene ether nitrile (BP‐PEN) matrix to prepare nanocomposite films with various mass fractions of CPEN‐f‐BaTiO₃@NH₂‐CuPc (0, 2.0, 5.0, 10.0 and 20.0 wt%). After that, the nanocomposite films were unidirectionally stretched with various stretching ratios at 280 °C. All the nanocomposite films show excellent mechanical and thermal stability, which is provided by the BP‐PEN matrix. The crystallinity and mechanical, thermal and dielectric properties of the nanocomposite films are efficiently enhanced after the unidirectional hot‐stretching process. The results show that hot‐stretching is a useful method for improving the mechanical and crystallization behaviors as well as the thermal and dielectric properties of the nanocomposite films. © 2017 Society of Chemical Industry     

Nanocomposites of a bismaleimide resin with octaphenylsilsesquioxane or nano‐SiO2

Nanocomposites were prepared from the resin of 4,4′‐bismaleimido‐diphenylmethane (BDM) with dipropargyl ethers of hexafluorobisphenol A (DPBPF) and octaphenylsilsesquioxane (OPS) or nano‐SiO₂. The nanocomposites were characterized by Fourier transform infrared spectroscopy, scanning electron microscope, dynamic mechanical analysis and thermogravimetric analysis. The results exhibited that OPS or nano‐SiO₂ particles could be easily dispersed in the nanocomposites and the glass transition and decomposition temperatures of c‐BDM‐DPBPF‐OPS and c‐BDM‐DPBPF‐SiO₂ nanocomposites were higher than those of c‐BDM‐DPBPF resin. The reinforcement of OPS was more effective than that of nano‐SiO₂ in the nanocomposites. POLYM. COMPOS., 2011. © 2010 Society of Plastics Engineers     

Thermal degradation behaviors of phosphorus–silicon synergistic flame‐retardant copolyester

A novel phosphorus‐containing poly (ethylene terephthalate) (PET) copolyester/nano‐SiO₂ composite (PET‐co‐DDP/SiO₂) was synthesized by in situ polycondensation of terephthalic acid (TPA), ethylene glycol (EG), [(6‐oxide‐6H‐dibenz[c,e] [1,2]oxaphosphorin‐6‐yl)‐methyl]‐butanedioic acid (DDP), and nano‐SiO₂. The morphology of PET nanocomposites was observed by using transmission electron microscope and scanning electron microscope. It was found that the SiO₂ nanoparticles were dispersed uniformly at nanoscale in the copolyesters with content 2 wt %. The thermal degradation behavior of PET nanocomposites was investigated by thermogravimetric analysis performed with air and nitrogen ambience. The activation energies of thermal degradation were determined using Kissinger and Flynn–Wall–Ozawa methods, respectively. The results obtained from Kissinger method showed that the activation energy was increased with the introduction of SiO₂. Moreover, the activation energy is decreased for PET‐co‐DDP system in nitrogen and air. The results also indicated that the SiO₂ and DDP had synergic effect on the early decomposition and the late charring in air. Furthermore, in the PET‐co‐DDP/SiO₂ system, the activation energy increased when the DDP component increased. However, the opposite results were obtained when the Flynn–Wall–Ozawa method was used. That was because the Doyle approximation stands correct as the conversion degree is from 5% to 20%. The effects of SiO₂ and DDP on the PET thermal degradation were lower in nitrogen than in air. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Coincorporation of nano‐silica and nano‐calcium carbonate in polypropylene

In this study, various polypropylene (PP) nanocomposites were prepared by melt blending method. The effects of different spherical nanofillers, such as 50 nm CaCO₃ and 20 nm SiO₂, on the linear viscoelastic property, crystallization behavior, morphology and mechanical property of the resulting PP nanocomposites were examined. Rheological study indicated that coincorporation of nano‐SiO₂ and nano‐CaCO₃ favored the uniform dispersion of nanoparticles in the PP matrix. Differential scanning calorimeter (DSC) and polarizing optical microscopy (POM) studies revealed that the coincorporation of SiO₂ and CaCO₃ nanoparticles could effectively improve PP crystallizability, which gave rise to a lower supercooling temperature (ΔT), a shorter crystallization half‐life (t_1/2) and a smaller spherulite size in comparison with those nanocomposites incorporating only one type of CaCO₃ or SiO₂ nanoparticles. The mechanical analysis results also showed that addition of two types of nanoparticles into PP matrix gave rise to enhanced performance than the nanocomposites containing CaCO₃ or SiO₂ individually. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

The properties (rheological,dielectric, and mechanical) and microtopography of spherical fullerene‐filled poly(arylene ether nitrile) nanocomposites

Poly (arylene ether nitrile)/fullerene (PEN/fullerene) nanocomposites were prepared by a facile solution‐cast method and the rheological, dielectric, mechanical, and morphological properties of the resulted nanocomposites were systematically studied and compared. Rheological studies showed PEN/fullerene nanocomposites percolation network formed at fullerene containing of 1.50 wt %, when the shear frequency was fixed at 0.1 Hz, the fitted rheological percolation threshold was about 1.55 wt %, very close to the experimental observations. The dielectric transaction occurs when the fullerene loading reached 1.50 wt %, that is very close to its rheological percolation threshold. At this point, PEN/fullerene nanocomposites also showed the optimal mechanical properties with a tensile strength of 93.6 MPa and modulus of 1951.5 MPa, which is increased by 27% and 15% compared with the pure PEN. SEM and TEM images have manifested the separate fullerene aggregated to fullerene bundles in PEN/fullerene nanocomposites, and the dispersion of fullerene bundles begin to go bad when the containing above 1.50 wt %. The PEN/fullerene nanocomposites can be widely used due to its excellent dielectric and mechanical performance. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40100.     

Effect of amphoteric dispersant on the dispersion properties of nano‐SiO2 particles

An amphoteric polycarboxylate dispersant (APC) was synthesized by copolymerization of acrylic acid (AA), methacryloxyethyltrimethyl ammonium chloride (DMC), and isopentenol polyoxyethylene ether (IPEG). The molecular structure of APC was characterized by FT‐IR, ¹H‐NMR, and GPC. Effect of the dosage of APC on the rheological performance of nano‐SiO₂ suspension was investigated by measurements of the plastic viscosity. The results indicated that the best dispersion effect of APC was obtained when the dosage of APC was about 10 wt % (by the weight percent of nano‐SiO₂), which can maintain the dispersion of nano‐SiO₂ suspension uniformly for 4 h without settlement. Meanwhile, the zeta potential value on the surface of nano‐SiO₂ particles shows that the better dispersion performance of APC was attributed to the solvation water film formed by the polyoxyethylene side chains and the electrostatic repulsion formed by positively groups (C?N⁺) on the APC structure combined with ‐SiO^– groups on the surface of nano‐SiO₂ particles. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45075.     

Effects of nanosilica on retrogradation properties and structures of thermoplastic cassava starch

Composites of thermoplastic cassava starch (TPS) and nanosilica (SiO₂) were prepared by the melting method. The effect of nano‐SiO₂ on the retrogradation properties and structures of cassava starch was investigated. The retrogradation degree of TPS/nano‐SiO₂ composites increased with increasing retrogradation time. The retrogradation rate of TPS significantly increased after the addition of nano‐SiO₂, but excessive nano‐SiO₂ content leads to a decrease in the retrogradation rate of TPS. According to the Fourier transform infrared spectroscopy results, the retrogradation degree of TPS/nano‐SiO₂ composites increased with the increase of retrogradation time and addition of nano‐SiO₂. Scanning electron microscopy analysis indicated that nano‐SiO₂ particles were uniformly and finely dispersed in the starch materials, but the nano‐SiO₂ particles aggregated in the cassava starch with a further increase in nano‐SiO₂ content. X‐ray diffraction revealed that the crystalline structure of the starch was gradually altered from A‐type to V‐type with the increase of retrogradation time. TPS/SiO₂ composites indicated a mixture of A+V types, and the intensity of the V‐type strengthened with the increase of retrogradation time and SiO₂ content. Polarized light microscopy analysis revealed clear Maltese cross patterns, and the number of spherulites in TPS/nano‐SiO₂ composites increased with increasing retrogradation time and nano‐SiO₂ content, but the retrogradation of starch was inhibited with further increases of nano‐SiO₂ content. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45687.