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A fast light-actuated shape memory polymer (SMP) composite with greatly enhanced photothermal conversion and mechanical stiffness was prepared by incorporating gold nanoparticle/reduced graphene oxide (AuNP-RGO) hybrids into cross-linked poly(e-caprolactone) (PCL). The AuNP-RGO hybrids with AuNPs uniformly anchored on RGO sheets were obtained in a water/n-butylamine system. Due to the homogeneous dispersion of AuNP-RGO in PCL matrix and the synergistic effect of photothermal conversion, the AuNP-RGO hybrids imparted the PCL with fast near-infrared (NIR) light-actuated shape recovery effect, and the light-actuated shape recovery speed could be accelerated via the increase of AuNP loading on RGO sheets. Moreover, the SMP composites possessed high shape recovery stress due to the incorporation of AuNP-RGO, thus they could be used as heavy-lift actuators. This SMP composites with enhanced light responsivity and mechanical properties are believed to have great potential in many fields such as light energy harvesting and remote-controlled actuators.

In this work, three kinds of boron nitride (BN) particles with different sizes were combined with carbon nanotubes (CNTs) to prepare the poly(vinylidene fluoride) (PVDF) composites. The dispersion states and the hybrid network structure of fillers were investigated. The results showed that the dispersion states of CNTs were greatly influenced by the size of BN particles. Relatively high density of hybrid network structure of fillers was obtained in the ternary composites containing the smallest BN particles (0.16 μm), while the composites containing the biggest BN platelets (22.02 μm) showed the low density of the hybrid network structure. Thermal conductivity measurements showed that BN particles with moderate size (8.70 μm) were the most appropriate filler to construct the highly efficient thermal conductive path with CNTs and in this condition, the ternary composites exhibited the highest thermal conductivity.

Phase change materials (PCMs) have wide applications in many fields and they are thought to be one of the highest potential materials in the future. Developing advanced PCMs faces various problems, such as low thermal conductivity, poor shape stability and single energy conversion pattern, etc. In this work, novel composite PCMs were fabricated based on the commercial melamine foam (MF) incorporated by the graphene oxide (GO) and graphene nanoplatelets (GNPs). After hydrothermal reaction and carbonization, the composite aerogel still maintained the three-dimensional (3D) composite framework structure with reduced GO (rGO) and GNPs covering on the carbonized MF framework. The composite PCM samples exhibited high shape stability without leakage under the load of 265 times of its own mass at temperature much higher than the phase change temperature of paraffin wax (PW), high phase change enthalpy retention rate (nearly 100% of PW), high thermal conductivity (1.46 W/m·K) and electrical conductivity (2.787 S/cm) at a filler content of 4.89 wt%. Moreover, the composite PCM samples have excellent light-to-thermal and electric-to-thermal energy conversion abilities, which endow the composite PCMs with great potential in diverse applications, such as the energy saving and heat preservation of building and temperature protection of microelectronic devices, etc.

Polyamide-based composites with segregated Carbon nanotube (CNT) network were prepared to achieve a high dielectric constant with an ultralow loading of CNTs. Specially, the polypropylene (PP) was introduced into the segregated CNT network to tailor the CNT dispersion. More importantly, the PP layer formed between two neighbored CNTs can enhance the interfacial polarization and suppress the electron conduction, leading to a higher dielectric constant while maintaining the dielectric loss at a low level. In this work, CNT segregated structure was firstly applied to achieve polymer composites with high dielectric constant but low loss.

Phase change materials (PCMs) exhibit wide application prospects in many fields related to energy utilization and management and attract increasing interest. In this work, through the graphene oxide (GO)-assisted dispersion technology, GO/boron nitride (BN) nanosheets were incorporated into melamine foam and successfully deposited on the surface of the foam framework after hydrothermal reaction. Through the following freeze-drying and carbonization treatment, the composite MF/rGO/BN aerogels were obtained with integrated hybrid rGO/BN frameworks. The composite PCMs were prepared through encapsulating polyethylene glycol (PEG) within the hybrid aerogels. The encapsulation stability and thermal properties of the composite PCMs were systematically investigated. The composite PCM sample containing the highest content of rGO/BN exhibited excellent encapsulation stability, high thermal conductivity (up to 0.79 W m-1 K-1), high phase change enthalpy (160.7 J g-1) with the retention of 90.8% of the pure PEG, and excellent chemical and thermal stability. Further results clearly showed that the composite PCMs had excellent light-to-heat energy transition ability and could be used as a thermal management component to suppress the overheating of devices during the operation process, or to supply energy for thermoelectric devices under emergency conditions to ensure a continuous power supply sustained for a certain time until the safeguard procedures are adopted.

Helical carbon nanotube (HCNT) is a vital member of carbon nanomaterials, but little effort was devoted to explore its unique characteristics and applications during the past few decades. Here, we report an organic thermoelectric composite with an excellent photothermoelectric (PTE) effect by conformally wrapping polypyrrole (PPy) on the intricate surface of HCNTs, which have been confirmed to have remarkable near-infrared (NIR) photothermal conversion capability and ultralow heat transportation characteristics. The results indicate that with the increasing HCNT content, PPy shell thickness reduces and exhibits denser as well as partial orientation, while the inter-ring angle slowly decreases and the bipolaron becomes dominant in carrier composition gradually. Consequently, the Seebeck coefficient increases monotonically, whereas the electrical conductivity remains nearly invariant. The final composite combines the benign thermoelectric properties, excellent photothermal response performance, and the lowest thermal conductivity of the carbon-based thermoelectric composite yet reported (0.064 W m-1 K-1). A single strip NIR light-stimulated adjustable delay switch was designed and fabricated, with the open-circuit voltage and short-circuit current under a 400 mW cm-2 NIR-stimulated approach to 720 μV and 62 nA with the discrepancy of consecutive periodic output signals less than 4.2%, exhibiting incredible stability and reliability and demonstrating the highest output voltage of a single strip among the reported organic PTE composite at room temperature. Our work fills in a gap of HCNT research, which hitherto existed in the PTE and thermoelectric field.

Tailoring the distribution of nanoparticles and further constructing effective microcapacitors in polymer blends are important issues for developing high-performance polymer dielectric nanocomposites. The common method to control the selective localization of nanoparticles in an immiscible polymer blend is relatively difficult and it easily results in the accumulation of nanoparticles in one component, which usually leads to a dramatic increase of the dielectric loss in the nanocomposites. In this work, a novel strategy based on step-by-step crystallization has been proposed to tailor the refined distribution and dispersion of carbon nanotubes (CNTs) in a melt-miscible blend poly(butylene succinate)/poly(vinylidene fluoride) (PBS/PVDF) through the crystallization-induced phase separation and the engineered interfacial affinity between CNTs and polymer components to acquire high dielectric constant and low dielectric loss. The results reveal that PBS is excluded along the growth front of PVDF spherulites and locates in the margin areas of PVDF spherulites during the step-by-step crystallization process. Moreover, because of the higher interfacial interaction between CNTs and PBS, CNTs are located in the PBS-rich domain, resulting in a high concentration of CNTs in the interspherulites of PVDF. Thus, the dielectric constants of the nanocomposites are greatly improved by nearly 5-24 times compared with the nanocomposites achieved by quick cooling and, simultaneously, the dielectric loss of the nanocomposites is still maintained at a low level. This work shows that the step-by-step crystallization method can be used to fabricate the nanocomposites with a synergistic increase in the dielectric performance due to the formation of a refined microcapacitor assembly. To the best of our knowledge, this is the first report to show that the dielectric constant of the nanocomposites can be greatly enhanced just through the crystallization-optimized distribution and dispersion of CNTs in immiscible polymer blends, and it possibly gives a new technical route for the fabrication of advanced dielectric composites.

Polymeric dielectric composites have wide applications in many fields ranging from wearable devices, sensors to energy storage. In this work, a novel kind of hybrid particles with ‘core-shell’-like structure were fabricated via the polydopamine-assisted deposition technology, in which the tetra-pod zinc oxide whisker (T-ZnOw) was the ‘core’ and the two-dimensional graphene oxide (GO) was the ‘shell’, while polydopamine (PDA) was the adhesion layer between T-ZnOw and GO. With the aid of PDA adhesion layer, the ‘core-shell’-like structure of the hybrid GO/PDA@T-ZnOw particles could be maintained in the poly(vinylidene fluoride) (PVDF) composites. Dielectric property measurements showed that the hybrid particles could be an excellent candidate to prepare the dielectric composites with excellent dielectric properties. There was a critical particle content (2.0–2.5 wt%) at which the composites exhibited the maximum dielectric constant and relatively low dielectric loss. Further results showed that GO and PDA@T-ZnOw particles had tremendous synergistic effect in enhancing the dielectric properties of the composites. The mechanisms for the largely enhanced dielectric constant were mainly related to the multiple interfaces in the composites, including the interfaces between GO and PVDF, between GO and PDA and between PDA and T-ZnOw, which provided more probability for interfacial polarization of the composites in the electrical field. This work presents a guideline to design high-performance dielectric composites with construction of the multiple interfaces.

In this work, poly(vinylidene fluoride)/poly(methyl methacrylate) (PVDF/PMMA) blend (50/50, wt/wt) and its blend composites containing carbon nanotubes (CNTs, 0.2 and 0.5 wt%) were prepared. Two types of PMMA with relatively large (PMMA-L) and small (PMMA-S) molecular weights were used to prepare the materials. It was observed that PVDF had higher crystallization ability in the samples containing PMMA-S. CNTs exhibited nucleation effect on the crystallization of PVDF and their nucleation efficiency was influenced by the molecular weight of PMMA. Rheological measurements showed that concentration fluctuation occurred during the melt annealing process even if the blend should be miscible at this temperature range, and more apparent concentration fluctuation was observed for the samples containing PMMA-S. Incorporating CNTs restrained the concentration fluctuation of the blend under the shear condition. Further results showed that larger concentration fluctuation in the melt state facilitated the higher crystallization ability of PVDF in the subsequent cooling process.

In this work, a small quantity of carbon nanofibers (CNFs) were incorporated into polypropylene/ethylene-propylene-diene terpolymer (PP/EPDM) blends. The effects of CNF content on the processing flowability, the microstructure of PP matrix and the morphology of elastomer particles were investigated. The results showed that the processing flowability of the material was not apparently influenced. The straight CNFs selectively located in the PP matrix and exhibited oriented dispersion along the flow direction of melt during the injection molding processing. CNFs exhibited nucleation effect on crystallization of PP. Homogeneous EPDM particles with smaller particle diameters were obtained in the blend composites. Mechanical properties measurements showed that the largely enhanced fracture toughness was achieved for the blend composites and the brittle-ductile transition was induced at lower EPDM content. Specifically, incorporating only 0.2 wt% CNFs into the PP/EPDM (85/15), the impact strength was enhanced about 246%. Further results showed that for the blend which exhibited brittle-fracture feature, the brittle-ductile transition could also be induced with increasing CNF content. The toughening mechanisms were then proposed.

In this work, polydopamine (PDA) coated GO (PDA-c-GO) aerogels with different GO concentrations and GO/PDA ratios were prepared through the solution compounding and subsequent freeze-drying technologies. Microstructures and morphologies of these aerogels were comparatively characterized. Subsequently, the structure stability in different solution conditions and adsorption properties toward organic dyes and solvents were investigated in details. The results show that the self-polymerized PDA can be homogenously coated on GO sheets with polymerization time longer than 3 h, and the surface morphologies are greatly influenced by the GO concentration and GO/PDA ratio. Higher GO concentration and GO/PDA ratio lead to better structure stability in water solutions. Furthermore, all the aerogels can keep stable in cyclohexane. The excellent adsorption ability toward Methylene blue (MB) is obtained for the PDA-c-GO aerogels, among which the aerogel of 1.0 mg/ml-2:1 exhibits the highest adsorbing amount (633 mg/g) and rate. Moreover, the good adsorbing selectivity and excellent adsorption ability for organic solvents are also obtained for the PDA-c-GO aerogels. In general, the PDA-c-GO aerogels with excellent adsorption properties are successfully prepared and they possibly have a great application potential in the field of waste water treatment.

The incorporation of CNTs into the immiscible blends are increasingly attractive because of high performance, its wide application and great prospects for development in the future. The objective of this review focuses on CNTs toughened immiscible polymer blends based on the selective localization of CNTs in the immiscible blends. Firstly, the thermodynamic and kinetic factors that determines the localization of CNTs are introduced. The former is relative to the wetting coefficient that can be applied to evaluate the favorable polymer component for CNTs; and the latter relates to the migration of CNTs in polymer blends. Combined with the morphology evolution accompanying with the incorporation of CNTs, the selective localization of CNTs can be distributed in dispersed phase, continuous phase or at the interface, exhibiting different unique properties. Among these properties, CNTs toughened the immiscible polymer blends can be found in these two cases: CNTs disperse in one phase (droplets or continuous) or CNTs disperse at the interface. With the presence of CNTs in immiscible blend, the toughening mechanisms involve: 1) the formation of percolative CNTs network; 2) formation of “cross-linked”-like structure; 3) morphology evolution; 4) compatibilization of immiscible blends; 5) nanobridge effect of CNTs at the interface. This review details recent works for the above mentioned selective localization of CNTs in immiscible blend and corresponding the toughening mechanisms of CNTs for immiscible blends, which is proposed to provide a guidance for the polymer toughening.

In this work, polypyrrole (PPy) particles were first decorated on the surface of graphene oxide (GO), then the hybrid PPy@GO particles were incorporated into poly(vinylidene fluoride) (PVDF) to prepare the PVDF/PPy@GO composites. The microstructure characterizations showed that PPy particles were successfully decorated on the GO platelets and simultaneously, GO was partially reduced. With the aid of GO, PPy particles with much smaller diameters exhibited good dispersion in the PVDF/PPy@GO composites. Interestingly, different from the apparent nucleation effect of PPy particles on PVDF crystallization, the nucleation effect of PPy particles in the PVDF/PPy@GO composites was greatly reduced. The PVDF/PPy@GO composites exhibited higher electrical conductivity compared with the PVDF/PPy composites. More interestingly, compared with the PVDF/PPy composites, largely enhanced permittivity and slightly reduced dielectric loss were simultaneously achieved for the PVDF/PPy@GO composites. The mechanisms were related to the construction of multiple-interfacial polarization and the enhanced conductivity of the composites.

Polycarbonate/poly(butylene terephthalate) (PC/PBT) blends exhibit wide applications in many fields. However, the blends usually exhibit poor mechanical and thermal properties because of the transesterification reaction occurred between molecules of the blend components. In this work, a small quantity of carbon nanotubes (CNTs) was introduced into the PC/PBT blend to prepare the ternary blend composites with balanced macroscopic properties. The dispersion of CNTs in the blend composites and the microstructural changes induced by CNTs were comparatively investigated. The results demonstrated that CNTs exhibit relatively homogeneous dispersion in the blend composites. Specifically, at relatively high content, CNTs form the percolated network structure. The crystallization ability of the PBT component is greatly enhanced with the aid of the nucleation effect of CNTs. Mechanical property measurements showed that CNTs exhibit strengthening and toughening effects on the PC/PBT blend, especially incorporating 2 wt% CNTs leads to the dramatic increase of tensile ductility. Further results showed that the blend composites also exhibit excellent antistatic performance. It is believed that the simultaneously improved fracture toughness and antistatic performance endow the blend composites with more potential applications.

In this work, simultaneously enhanced thermal conductivity, heat dissipation and dielectric constant of poly(vinylidene fluoride) (PVDF) were prepared by adding ionic liquid (IL)-coated carbon nanotubes (IL@CNTs). IL@CNTs and common CNTs were melt-compounded with PVDF to prepare the composites, respectively. The results clearly demonstrated that IL@CNTs exhibited better dispersion and higher ability to form the percolated network structure. Studying on crystallization behaviors showed that IL@CNTs not only exhibited better nucleation effect on PVDF crystallization but also induced a large number of the polar β/γ-form crystallites formation in the composites. Thermal properties measurements showed that IL@CNTs exhibited more apparent role in enhancing the thermal conductivity of the composites. Specifically, IL@CNT endowed the composite sample with higher heat dissipation ability compared with the common CNTs during the cooling process. In addition, the largely enhanced dielectric constant was also achieved for the PVDF/IL@CNT composites. The mechanisms were analyzed and suggested to be mainly related to the improved dispersion and denser percolated network structure of IL@CNTs in the composites, the improved interfacial interaction between fillers and matrix, and the varied crystalline structure of the PVDF matrix. The prepared composites have great potential application as the heat management material of the flexible electronic devices.

Biodegradable poly(L-lactic acid) (PLLA) based blend composites with excellent toughness exhibit comprehensive applications and they can be substitute for the common polyolefin and polyester based composites. To date, various strategies have been developed to enhance the toughness of the PLLA based blends or composites. Here, carbon nanofibers (CNFs) incorporated PLLA/poly(butylene adipate-co-butylene terephthalate) (PBAT) blend composites were investigated. The crystallinity of the PLLA matrix were precisely tailored through annealing treatment. Interestingly, CNFs and PBAT particles self-assembled into the “mutton kebab”-like structure during processing. In addition, the annealing treatment facilitated the epitaxial crystallization of PLLA on the surface of CNFs that were not covered by PBAT due to the excellent heterogeneous nucleation effect of CNFs. Consequently, with the addition of 1 wt% CNFs and tailoring the blend composite with the PLLA crystallinity of about 32.6%, the impact strength of the composite was increased by 270% from 10.0 kJ/m2 to 37.0 kJ/m2. The toughening mechanisms were mainly connected with the greatly strengthened interfacial interaction between PLLA matrix and PBAT particles by CNFs through CNFs bridging effect and CNFs inducing PLLA crystallization, facilitating the transfer of stress under the load condition, especially at high PLLA crystallinity. Furthermore, it was found that CNFs exhibited outstanding photothermal conversion effect, which could endow the blend composites with mechanical-damage-healing ability. This work not only reveals the role of crystalline structure in toughening of the PLLA-based blend composites but also paves an effective way to prepare super-toughened, biodegradable, heat resistant and mechanical-damage-healing PLLA-based composites via tailoring the crystalline structure of the matrix.

Interfacial polarization between fillers and polymer matrix in polymer composites would be responsible for enhancement of dielectric constant ( e ˊ ), but the dielectric mismatch between fillers and polymer also leads to an undesirable electric breakdown. Herein, we successfully developed a core-shell structured barium titanate@silver (BaTiO3 @Ag, BT@Ag) novel heterogeneous fiber via coaxial electrospinning followed by calcination technology, to simultaneously improve the dielectric property and breakdown strength ( E b ) of poly(vinylidene fluoride) (PVDF)-based composites. Dielectric measurement reveals that PVDF/BT@Ag composites have an enhanced e ˊ , low dielectric loss (tan δ) and moderately increased E b . Since the core-shell structured fibers help in tailoring the local electric field around the interface, but also provide double interfacial polarization, which effectively improves the dielectric properties of the composites. When the loading of BT@Ag reached up to 10 wt%, the e ˊ increased to 19.4 @1 kHz while the E b had maximum value of 389.1 MV/m, finally resulting in an improvement of U e . Moreover, the incorporation of BT@Ag obviously improves the mechanical properties of composites. It is expected that these results would further inspire the design of fillers with novel architecture for high-performance dielectric polymer composites.

Structural relaxation of polymer chains exhibits high correlation to the macroscopic performance of polymers, and it has been well investigated and analyzed in the polymer systems. However, it is still challenging to accurately describe the structural relaxation of some complex systems, such as the nanomaterials incorporated blends. In this work, structural relaxations in the poly (vinylidene fluoride)/poly (methyl methacrylate) (PVDF/PMMA) blends in the presence of graphene oxide (GO) were systematically investigated via revealing the cooperativity concerning about segmental relaxation, chain relaxation relating to the crystallization behaviors using the broadband dielectric spectroscopy (DRS). In the presence of GO, the cooperative volume was enlarged and dynamic heterogeneity was weakened. And the chain relaxation α c moved to higher frequency; while the α m relaxation associated with molecular motion in miscible amorphous region of PVDF/PMMA blends can be well resolved. Thus, the structure relaxations confirmed that GO could hinder the crystallization of PVDF but enhance the miscibility in the PVDF/PMMA amorphous phase. On the basis of structure relaxations, the dielectric properties as function of temperature and frequency were accordingly studied, and at room temperature PVDF/PMMA blends in the presence of GO exhibited higher constant and lower loss at low frequency regions.

In this work, carbon nanotubes (CNTs) were introduced into miscible poly(l-lactide)/poly(vinyl acetate) (PLLA/PVAc) blend and the crystallization behaviors of PLLA with the presence of PVAc and CNTs are systematically discussed. The dispersion state of CNTs was characterized using scanning electron microscope, and the crystallization behaviors of PLLA in different conditions including melt crystallization and cold crystallization were comparatively investigated using polarized optical microscope, differential scanning calorimetry and wide angle X-ray diffraction. The results showed that the crystallization of PLLA was greatly restricted by PVAc. CNTs exhibit apparent nucleation effect, promoting the occurrence of both melt crystallization and cold crystallization. However, the nucleation effect of CNTs in the ternary composites is weakened as compared with that in the binary PLLA/CNTs composites. It was suggested that the relatively higher interfacial affinity between PVAc and CNTs, which possibly resulted in more PVAc molecule rather than PLLA molecule around the surface of CNTs, was the main reason for the reduced nucleation efficiency.

In this work, polystyrene-grafted reduced graphene oxides (rGO-PS) were prepared via the emulsion polymerization with reserving the two-dimensional layer-like structure of graphene. TGA, FTIR, Raman results show that the amounts of polystyrene (PS) grafted on rGO from low to medium, high values can be tuned via incorporating different content of styrene in the PS polymerization recipe. Subsequently a series of PS-based composites containing different loading of rGO with variant amount of PS grafted on rGO were prepared. The effects of grafting amount on the resulting dielectric properties were carefully investigated. Compared with the composites containing rGO without any treatment, significantly increased dielectric constant and lower dielectric loss are observed for the composites with rGO-PS. Moreover, with increasing the amounts of grafted PS on rGO, the dielectric constants exhibit an increasing trend whereas the dielectric loss keeps at a stable level. For instance, when the loading of filler is fixed at 5 wt%, the composites containing rGOs with highest amount of grafted PS exhibit a maximum of dielectric constant 394.6@100 Hz, which is over 20 times larger than that of composites containing rGO. However, a relatively low dielectric loss tangent 0.45@100 Hz and conductivity 4.04 × 10 −9 S/cm@100 Hz are observed in the composites containing rGOs with highest amount of grafted PS, which is even lower than that of composites containing rGO. The improved interfacial polarization induced by the constructed PS layer between rGO and PS matrix is invoked to be responsible for the improved dielectric constant; on the other hand, the PS layer can restrict the conduction loss and suppress the dielectric loss. This work indicates that the dielectric performance of composites could be effectively ameliorated through the strategy of reasonably designing the interface structure of conductive fillers.

Degradable polyesters exhibit wide application in many fields due to the fact that the waste of these polymers can be easily reclaimed, which greatly reduces the environmental risk. In this work, a small quantity of water-soluble poly(ethylene oxide) (PEO) was introduced into biodegradable poly(butylene succinate) (PBS). Crystallization behavior of the PBS matrix was comparatively investigated using polarized optical microscope (POM), differential scanning calorimetry (DSC) and wide angle X-ray diffraction (WAXD). The results demonstrate that PEO affects the crystallization behavior of the PBS matrix, which is greatly dependent upon the PEO content. At relatively low PEO content, accelerated crystallization is achieved for the PBS matrix, while the role of PEO becomes inconspicuous at relatively high PEO content. The sample surface hydrophilicity was evaluated through contact angle measurement of distilled water. The results demonstrate that incorporating PEO into PBS greatly enhances the hydrophilicity of the sample surface. The hydrolytic degradation measurements were carried out under an alkaline condition. The results clearly show that the presence of PEO accelerates the hydrolytic degradation of the PBS matrix. Furthermore, the sample obeys the surface erosion mechanism. The mechanism for the largely enhanced hydrolytic degradation ability is then analyzed.

In this work, we developed a green synthesis method to prepare the hybrid aerogels containing graphene oxide (GO) and microcrystalline cellulose (MCC) using lithium bromide (LiBr) aqueous solution as the solvent, which insured the complete dissolution of MCC. The interaction between GO and MCC was investigated through different methods The results demonstrate that there is a strong interaction between GO and MCC molecules, which promotes the exfoliation of GO in the hybrid aerogels. The hybrid GO/MCC aerogels exhibit typical three dimensional porous structure and the pore morphology can be well adjusted by changing the content of GO. The adsorption ability of the hybrid aerogels was measured using methylene blue (MB) as an adsorbate. The results show that the adsorption ability of GO per unit mass is greatly enhanced compared with the pure GO aerogel, especially at relatively low GO content the adsorption amount of GO per unit mass is enhanced up to 2630 mg/g. Further results demonstrate that the hybrid GO/MCC aerogels still obey the pseudo-second-order adsorption model, which is similar to that of the pure GO aerogel. The mechanism for the amplified adsorption ability of GO in the hybrid GO/MCC aerogels is then analyzed.

A small quantity of graphene platelets (GNPs) were introduced into polystyrene (PS) to prepare the PS/GNP composites through one-step process (solution compounding, PS/GNP-S) and two-step process (solution compounding and subsequent melt compounding, PS/GNP-SM). The dispersion states and microstructures of GNPs in the composites were comparatively investigated. The results demonstrated that the PS/GNP-S composites exhibited relatively poor dispersion of GNP particles but relatively high ability to form the percolated GNP network compared with the PS/GNP-SM composites. Apparently increased glass transition temperatures were achieved for the PS/GNP-S samples. Conductive properties measurements showed that the PS/GNP-S samples exhibited relatively low volume resistivity. Largely enhanced thermal conductivity was achieved for the PS/GNP-S samples, and the thermal conductivity exhibited nonlinear behavior with increasing GNP content, which was different from the linear behavior of the PS/GNP-SM samples. The conductive mechanisms of the composites were discussed using two different analytic models.

In this work, multiwall carbon nanotubes (MWCNTs) were melt compounded with a poly(ethylene vinyl acetate)/thermoplastic polyurethane (EVA/TPU) blend to prepare EVA/TPU/MWCNT blend nanocomposites. The effects of the blend morphology and selective localization of MWCNTs on the dielectric properties including dielectric constant and loss were systematically investigated. The results show that when the blend exhibits sea–island morphology accompanying MWCNT selective localization in island droplets, the dielectric constant was increased to 1200@100 Hz with addition of 5 wt % MWCNTs; in addition, the growth of dielectric loss is suppressed and the values of dielectric loss always remain around 1 with varying the loading of MWCNTs. Furthermore, based on the investigations of rheological percolation testing, morphological observation, and selective localization, the microcapacitor model was evoked to explain the underlying mechanism for the improvement of the dielectric constant for the blend with sea–island mo...

Brittle-ductile transition is a well-known phenomenon in the elastomer-toughened polymer blends, and it is usually used to value the toughening efficiency of the elastomers. In this work, a small quantity of carbon nanotubes (CNTs) were introduced into the polypropylene/ethylene-propylene-diene terpolymer (PP/EPDM) blends to investigate the effect of CNTs on the brittle-ductile transition of the blends. The mechanical properties, morphologies and the crystallization behaviors of samples were comparatively investigated. The results showed that CNTs not only enhanced the impact strength of the materials but also promoted the occurrence of brittle-ductile transition at relatively low EPDM content. The crystallization and melting behaviors of PP matrix were not apparently influenced by CNTs, which could be attributed to the selective localization of CNTs in the EPDM component. Further results demonstrated that the toughening efficiency of CNTs in the blend composites was dependent upon the matrix ligament thickness ( τ ), and there was an appropriate range of τ (0.85–1.15 μm), at which CNTs exhibited high toughening efficiency. This work provides new insight on the toughening effect of CNTs in the immiscible polymer blends.

Plasticized poly(L-lactide) (PLLA) materials have been applied in many fields and the microstructure performance of such materials attracts much attention of researchers. However, few reports declared the hydrolytic degradation ability of the plasticized PLLA materials. In this article, a small quantity of poly(ethylene glycol) (PEG) was introduced into PLLA, which aimed to understand the hydrolytic degradation behavior of the plasticized PLLA materials. The microstructures of the plasticized samples were comparatively investigated using scanning electron microscopy (SEM), wide angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC) and Flourier transform infrared spectroscopy (FTIR), etc. The results demonstrated that PEG improved the hydrophilicity of sample surface, and the relatively high content of PEG enhanced the crystallization ability of PLLA matrix. The hydrolytic degradation measurement was carried out at 60 °C in an alkaline solution of pH = 12. The results demonstrated that the plasticized PLLA samples exhibited accelerated hydrolytic degradation compared with the pure PLLA sample, and the hydrolytic degradation was also dependent on the PEG content. Further results demonstrated that PEG induced the change of hydrolytic degradation mechanism possibly due to the good dissolution ability of PEG in water, which provided more paths for the penetration of water. Furthermore, the microstructure evolution of the plasticized PLLA during the hydrolytic degradation process was also investigated, and the results demonstrated the occurrence of PLLA crystallization, which was possibly contributed to the decreased hydrolytic degradation rate observed at relatively long hydrolytic degradation time. This work is of great significance and may open a new way for promoting the reclamation of PLLA waste material.

In this work, poly(vinylidene fluoride) (PVDF)/graphene oxide (GO) were prepared through a two-step processing procedures, i.e. solution compounding and subsequent melt compounding processing. The thermal reduction of GO during the sample preparation process, the dispersion state of GO in the composites, and the crystallization of PVDF matrix were comparatively investigated. The results demonstrated that the partially reduced GO could be obtained during the sample preparation process. The residual oxygen-containing groups induced the crystal transformation of PVDF matrix from α-form to β-form on one hand. On the other hand, there was specific interfacial interaction between oxygen-containing groups of GO and >CF 2 group of PVDF matrix. The PVDF/GO composites were still insulated. High dielectric constant and low dielectric loss were achieved for the PVDF/GO composites with GO content higher than 1 wt%. The mechanisms for the excellent dielectric properties were proposed to be related to the interfacial polarization of the partially reduced GO, the formation of polar β-form PVDF crystallites and the formation of local GO network structure.

The morphology, as well as the distribution of conductive fillers in conductive filler/polymer nanocomposites has a decisive effect on dielectric properties of blend composites. In this study, the relationship between morphology and properties are carefully investigated and the underlying mechanism was discussed based on the micro-capacitors model. Multiwalled carbon nanotubes (MWCNTs) were introduced into an immiscible poly(vinylidene fluoride) (PVDF)/polyamide 6 (Nylon 6) blend and the morphologies of PVDF/Nylon 6 were tailored by changing the weight ratio of PVDF to Nylon 6, varying from sea-island morphology to cocontinuous morphology. Interestingly, the CNTs are selectively localized in Nylon 6 phase in both sea-island and cocontinuous morphological blends, which are due to the finer interaction between Nylon 6 and CNTs. Only in sea-island morphological blend, a great increase of dielectric permittivity can be found when increasing the content of CNTs. It is surprised found that no effects of CNTs on dielectric properties can be found in cocontinuous morphological blend. In this case, the CNTs filled Nylon 6 domains in sea-island morphological blend act as a micro-capacitor with an improved charge accumulation and interfacial polarization, resulting in a great increase in dielectric permittivity.

Toughening modification is always one of the main subjects of structural materials. A small quantity of dicumyl peroxide (DCP) and carbon nanotubes (CNTs) were simultaneously introduced into an immiscible poly( l -lactide)/poly(ethylene vinyl acetate) (PLLA/EVA) blend through melt compounding processing. The presence of chemical cross-linking structure in the polymer components and the physical network of CNTs were demonstrated through a series of direct and indirect characterization methods. The results demonstrated that DCP and CNTs exhibited synergistic toughening effects and the dynamically vulcanized blend composites exhibited excellent impact toughness. This work provides an alternative way to improve the impact toughness of an immiscible polymer blends.

Creep stability is usually adopted to evaluate the dimensional stability of polymers under the load condition. However, the creep behavior of polymer blend composites, which has been already used in many fields, is seldom investigated. In this work, immiscible poly( l -lactide) (PLLA)/poly(ethylene vinyl acetate) (EVA) blend composites with different contents of carbon nanotubes (CNTs) were prepared. The crystalline structure of matrix, the dispersion of CNTs as well as the morphologies of the blend composites were comparatively investigated. The results demonstrated that CNTs selectively located at the blend interface and induced the morphological changes from quasi-cocontinuous structure to cocontinuous structure. Mechanical property measurements demonstrated that CNTs exhibited toughening effect for the immiscible PLLA/EVA blends. The creep behavior was investigated under different external forces. The results demonstrated that the creep stability of the blend composites was apparently enhanced by adding CNTs. The mechanisms for the enhanced creep stability were then proposed.

Background and objective: Cataract with glaucoma can adversely affect visual acuity and corneal endothelial cells. Studies have shown that after phacoemulsification combined with trabeculectomy in patients with cataract and glaucoma, blood lipid ratio and insulin sensitivity are associated with intraocular pressure, visual acuity and corneal endothelial cells, which may be used for the evaluation of efficacy. Interleukins are the main mediators of the inflammatory response and are involved in the pathogenesis of cataract. In this trial, we will examine the postoperative changes in interleukin-10, interleukin-2 and interleukin-1β levels in patients with cataract with glaucoma, and analyze the correlation between insulin sensitivity and corneal endothelial cell density to assess whether inflammatory factors can be used to evaluate efficacy. Participants and methods: This prospective, single-center, open-label, self-controlled clinical trial will include 160 patients with cataract combined with glaucoma, 35–65 years of age, from the Department of Ophthalmology, First Affiliated Hospital of Kunming Medical University, China. All patients will receive phacoemulsification and trabeculectomy, and will be followed up at 5 days, and at 1 and 3 months. Patient recruitment will begin on December 30, 2019 and end on December 30, 2020. Analysis of the results will be performed from May 1, 2021 to May 30, 2021. This study is scheduled to end on June 30, 2021. This study was approved by the Medical Ethics Committee, First Affiliated Hospital of Kunming Medical University, China, on December 15, 2013 (approval No. 20131215085), and will be performed in accordance with the principles of the Declaration of Helsinki, adopted by the World Medical Association. Study protocol version is 1.0. Written informed consent to participate will be obtained from each participant. Results: The primary outcome measure will be serum interleukin-2 level, as an index of the inflammatory response, 3 months after surgery. Secondary outcome measures will include serum interleukin-2 level before and 5 days and 1 month after surgery, serum levels of interleukin-1β, interleukin-10, C-reactive protein and tumor necrosis factor-α, best corrected visual acuity, endothelial cell density, mean cell area, coefficient of variation, insulin sensitivity index and intraocular pressure before and 5 days and 1 and 3 months after surgery, and incidence of adverse reactions at 5 days and 1 and 3 months after surgery. From January 2014 to June 2017, our team undertook and completed a small-sample study of 80 cataract patients (95 eyes) with glaucoma. The best corrected visual acuity was significantly improved, endothelial cell density and intraocular pressure were significantly reduced, interleukin-1β, interleukin-2, interleukin-10, C-reactive protein and tumor necrosis factor-α levels were significantly decreased (P Conclusion: The trial will confirm whether phacoemulsification combined with trabeculectomy has a good therapeutic effect in patients with cataract combined with glaucoma, and clarify whether the effect is associated with the regulation of insulin sensitivity index, corneal endothelial cells and inflammatory factors. Trial registration: This study was registered with the Chinese Clinical Trial Registry on September 10, 2019 (registration number: ChiCTR1900025837).

Thermally conductive epoxy composites have a broad range of applications in many fields relating to microelectronic devices and encapsulating materials of high-power electrical appliance. However, it is still a challenge to effectively fabricate thermally conductive epoxy composite materials that have various excellent comprehensive properties. In this work, a simple suction filtration method is developed to construct the self-supported framework of graphene nanoplatelets (GNPs) and carbon nanofibers (CNFs), and then epoxy is impregnated into the framework to prepare the composites. The morphological characterizations show that one dimensional CNFs exhibit the “supporting” effect between the parallelly arranged GNP layers in axial direction and the “bridging” effect between adjacent GNP aggregates in radial direction, and the self-supported framework is maintained in the epoxy composites. The highest thermal conductivities are 3.74 W/m·K in radial direction and 3.28 W/m·K in axial direction, at filler contents of 13.09 and 14.49 wt%, respectively, which are 1770% and 1540% higher than that of the pure epoxy. Further results show that the composite samples have high storage modulus, enhanced thermal resistance, and improved anti-friction performance, all of them ensure that the epoxy composites can be used as the materials of the components and parts of the electrical appliance toward continuous loading, vibration, and large heat dissipation.

In this work, chemically cross-linked poly(ethylene vinyl acetate) (EVA) was melt-compounded with poly(e-caprolactone) (PCL) to prepare the EVA/PCL blends. The chemical cross-linking reaction of EVA was induced by dicumyl peroxide (DCP) during the melt compounding processing. The effects of the cross-linking degree of the EVA component on the rheological properties, morphology, and melting and crystallization behavior of samples were systematically investigated. The results demonstrated that a morphological change from the quasi-cocontinuous structure to the typical cocontinuous structure was induced with increasing the cross-linking degree of the EVA components. Thermal properties measurements and dynamic mechanical properties measurements demonstrated that the EVA/PCL blends exhibited two independent thermal transitions. The shape memory behavior measurements showed that the samples exhibited excellent triple shape memory effects (triple-SME). The corresponding mechanisms were then analyzed.

Small quantities of maleic anhydride grafted styrene-ethylene-butylene-styrene (SEBS-g-MAH) copolymer and carbon nanotubes (CNTs) were introduced into polycarbonate (PC)/poly(butylene terephthalate) (PBT) blends. The results demonstrated that simultaneously adding SEBS-g-MAH and CNTs greatly enhanced the fracture toughness of the samples and the impact strength increased with increasing CNT content. The morphologies, the dispersion of CNTs, the relaxation behaviors and the crystallization behaviors of samples were systematically investigated. SEBS-g-MAH formed the dispersed particles in the system. The particle diameter was decreased in the blend composites. CNTs exhibited homogeneous dispersion in the blend composites and they also formed a percolated network structure at relatively high content. The transesterification between PC and PBT components was suppressed by SEBS-g-MAH, and the crystallization ability of the PBT component was greatly enhanced. The toughening mechanisms were mainly related to the suppressed transesterification, the decreased elastomer particle size, and the formation of a CNT network structure.

A small quantity of carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs) were introduced into the poly(vinylidene fluoride) (PVDF)/GNP and PVDF/CNT composites, respectively, to prepare the corresponding ternary PVDF/CNT/GNP and PVDF/GNP/CNT composites. The results demonstrated that adding CNTs into the PVDF/GNP composites greatly promoted the formation of the hybrid network structure of fillers. This was much different from the scenario that adding GNPs into the PVDF/CNT composites. GNPs and CNTs exhibited excellent nucleation effects for the crystallization of PVDF matrix; however, the variation of the PVDF crystallinity was small. Adding CNTs into the PVDF/GNP composites greatly enhanced the electrical conductivity of the PVDF/CNT/GNP composites. This was also different from the scenario of the PVDF/GNP/CNT composites. Furthermore, the PVDF/CNT/GNP composites exhibit higher thermal conductivity and higher synergistic efficiency compared with the PVDF/GNP/CNT composites. The conductive mechanisms and the synergistic effects of the ternary composites were then analyzed.

In this work, we developed a new kind of aerogel consisting of graphene oxide (GO) and polyvinyl alcohol (PVA), in which PVA exhibited a role to stabilize the 3D porous structure of GO. The PVA-supported GO aerogels were prepared through an environmentally friendly freeze-drying technique. The microstructure, the structure stability, the adsorption ability for different dyestuffs, and the oil/water separation of the aerogels were systematically investigated. The results demonstrated that the PVA-supported GO aerogels exhibited outstanding performances. First, the PVA-supported GO aerogels exhibited high structure stability, especially in the non-polar solvent, which was apparently different from the widely reported GO aerogels in the literatures which experienced structure collapse in the solvent, especially in water. Second, the aerogels also exhibited high absorption selectivity for dyes, especially for the dyes with positive charges; the adsorption efficiency was over 96%. Third, the PVA-supported GO aerogels still exhibited excellent oil/water separation ability and they can completely adsorb Sudan red/cyclohexane solution that floats on the water within 5 s. This work provides a simple and environmentally friendly method to obtain the versatile GO aerogel, which really has a great potential in the field of waste water treatment. Keywords: PVA-supported GO aerogel, Structure stability, Mechanical stability, Adsorption, Oil/water separation

In this work, the binary blend of poly(ethylene vinyl acetate) (EVA)/poly(e-caprolactone) (PCL) with different compositions were prepared and the shape memory behaviors were evaluated first. Then, carbon nanotubes (CNTs) were introduced into the composition that exhibited relatively better shape memory effect (SME) to prepare the ternary blend composites with electrically actuated SME. The morphologies of the blend and/or blend composites, the crystallization of the component, and the selective location states of CNTs in the blend composites were comparatively investigated. The results demonstrated that the binary EVA/PCL blends exhibit a typical sea–island structure at low PCL content, a quasi-cocontinuous structure at mediate PCL content and then the sea–island structure at high PCL content. Among these binary blends, the EVA/PCL (60/40) sample exhibits relatively better SME with not only high shape fixing ratio but also shape recovery ratio. The presence of the CNTs further induces the changes of morph...

In this work, dynamically vulcanized poly(l-lactide) (PLLA)/poly(ethylene vinyl acetate) (EVA) blends with different compositions were prepared. The morphologies, rheological properties and the crystalline structures of the samples were systematically investigated. The results demonstrated that with the increase of the PLLA component in the dynamically vulcanized samples, the blend morphologies varied from sea-island structure to cocontinuous structure, and then changed to sea-island structure again. A chemically cross-linked structure was introduced into the EVA component. Annealing treatment did not influence the crystallization of the EVA component, but it greatly promoted the cold crystallization of the PLLA component and consequently, a large amount of PLLA crystallites were emerged in the PLLA component. The shape memory behaviors of the dynamically vulcanized samples were detected, and the results showed that the samples exhibited good shape memory behaviors, which were greatly dependent upon the blend compositions and the annealing treatment. Samples with high content of EVA exhibited relatively higher shape fixity ratio (Rf) and shape recovery ratio (Rr). Although annealing treatment induced the decrease of Rf, largely enhanced Rr was obtained for the annealed samples, especially at relatively longer annealing time. The mechanisms for the enhanced shape memory effects of the annealed samples were then analyzed.

A small amount of carbon nanotubes (CNTs) was added into poly(vinylidene fluoride) (PVDF)/boron nitride (BN) composites through melt blending processing. The thermal conductivity, microstructure changes including the crystallization behavior of PVDF matrix and the dispersion states of fillers in the composites, and the electrical conductivity of the composites were comparatively investigated. The results demonstrated that compared with the PVDF/BN composites at the same BN content, the ternary PVDF/BN/CNT composites exhibited largely enhanced thermal conductivity. In the PVDF/BN/CNT composites, the crystallinity of the PVDF matrix was slightly increased while the crystal form remained invariant. BN particles exhibited homogeneous dispersion in the PVDF/BN composites, and they did not affect the rheological properties of the PVDF/BN composites when the BN content was lower than 10 wt %. The presence of CNTs did not affect the interfacial adhesion between BN and PVDF, but they facilitated the formation of d...

In this work, different contents of graphene oxide (GO) were introduced into poly(butylene succinate) (PBS) to study the effects of GO on crystallization of PBS matrix and the resultant hydrolytic degradation behaviors of the PBS/GO composites. The initial crystalline structures of PBS in the composites were investigated using a polarized optical microscope (POM), differential scanning calorimetry (DSC) and a wide angle X-ray diffraction (WAXD). The results demonstrated that GO showed nucleation effect for the crystallization of PBS matrix. However, high content of GO also restricted the growth of crystallite, resulting in the decrease of PBS crystallinity and the reduction of crystal size. The hydrophilicity of sample was evaluated by measuring the contact angle of water on the sample surface. The results demonstrated that the presence of GO greatly enhanced the hydrophilicity of the sample. The hydrolytic degradation behavior of sample in alkaline solution was investigated at 37 °C. The results showed that the hydrolytic degradation ability of PBS was greatly enhanced by adding GO. The more the GO in the composites, the higher the hydrolytic degradation ability was. The increased hydrophilicity that enhanced the wettability of sample surface by water, the decreased crystallinity of PBS matrix, and the presence of the defects in the composite, e. g. at the interface between the PBS matrix and GO particles, mainly contributed to the largely enhanced hydrolytic degradation ability of PBS. The microstructure changes during the hydrolytic degradation process were also analyzed. This work provided an alternative way to accelerate the hydrolytic degradation of PBS.

In this work, graphene oxide (GO) and polyvinylpyrrolidone (PVP) were introduced into poly(vinylidene fluoride) (PVDF) membranes that were prepared through phase inversion induced by immersion precipitation technique. The effects of GO and PVP on hydrophilicity, pore morphology and porosity of membranes were systematically investigated. The results demonstrated that GO and PVP exhibited synergistic effects in controlling the hydrophilicity, morphology and porosity of composite membrane. Largely enhanced hydrophilicity and porosity were simultaneously achieved for the PVDF/PVP/GO composite membrane. Furthermore, the effects of GO content on the morphology and porosity of composite membranes were also investigated. It was found that increasing GO content not only induced apparent changes of pore morphology but also induced the increase of the porosity of composite membrane. The adsorption ability of membranes were evaluated by immersing membranes in the solution of Methylene blue. It was found that the PVDF/PVP/GO composite membrane exhibited excellent adsorption ability for Methylene blue particles. The more the GO in the composite membrane was, the better the adsorption ability was. This work provides a highly effective method to greatly improve the hydrophilicity and adsorption ability of PVDF-based composite membrane with great potential in the field of wastewater treatment.

Here we demonstrated a remarkable improvement in the dielectric performance of poly (vinylidene fluoride) (PVDF)-based composites via incorporating distinguished hybrid nanofibers, namely, Ag nanoparticles-embedded BaTiO3 (Ag@BaTiO3, Ag@BT) nanofibers, which were fabricated by coaxial electrospinning technology followed by calcination. The Ag nanoparticles on BaTiO3 nanofibers were found to play a comprehensive role on the dielectric performances, including the better dispersion of hybrid nanofibers leading to homogeneity of electric field, the formation of charge transfer complex in the hybrid region which enhanced the interfacial polarization, and the Coulomb blockade effect of Ag nanoparticles to further suppress the interfacial charge accumulation. As a result, the PVDF/Ag@BT composites exhibited high dielectric constant of 38.87@1 kHz and low loss of 0.02@1 kHz.

Enhancing the synergistic efficiency of different fillers in the composites is very significant from viewpoints of reducing fabricating cost and acquiring promising comprehensive properties. Inspired by the stem parasitic plant cuscuta austrails (dodder), the highly efficient conductive network in the composites was constructed through the ‘rigid’ submicron vapor grown carbon fibers (s-VGCFs) and ‘reelable’ carbon nanotubes (CNTs), in which the homogeneously dispersed s-VGCFs acted as the framework while CNTs bridged adjacent s-VGCFs and also partly entangled on s-VGCFs. Compared with the binary composites containing only s-VGCFs (or CNTs), the presence of very small quantity of CNTs (or s-VGCFs) led to the significant reduction of percolation thresholds from 3.082 wt% to 0.876 wt% (or from 0.258 wt% to 0.024 wt%), and the extremely high synergistic efficiency of 1.5 × 107 was achieved. Specifically, the impact of different compounding sequences on the hybrid network structure of fillers was also discussed. This work provides a new strategy to construct the hybrid network structure of fillers with extremely high synergistic effect and it might be applied in fabrication of the conductive composites with excellent mechanical properties.

The advanced utilization of phase change materials (PCMs) is limited by the strong rigidity, liquid leakage and lack of photoabsorption ability. In this work, a novel form-stable PCM with solar-to-thermal energy storage ability and thermal/light-actuated shape memory property was prepared. Herein, paraffin wax (PW) served as a latent heat storage material and a switching phase for shape fixation, melamine foam (MF) acted as a supporting material to prevent the leakage and a permanent phase for shape recovery, and reduced graphene oxide (RGO) assembled on MF skeletons worked as a light absorption medium. Due to the light weight and abundant porosity of MF/RGO foam, the MF/RGO/PW PCMs possessed excellent encapsulation ability, high latent heat (144.8 J/g), good solar-to-thermal energy conversion and storage ability. Simultaneously, combining the elasticity of MF/RGO foam, the MF/RGO/PW PCMs exhibited thermal/light-sensitive shape memory property by triggering the phase transition of PW. The MF/RGO/PW PCMs showed excellent cyclic shape memory performance and thermal reliability. A light-sensitive and temperature-controlled board was further exploited, which could be installed on the roof of the house and maintained the temperature constancy. This study provides a strategy to prepare flexible, light-sensitive and form-stable PCMs via using the elastic MF/RGO foam as a supporting scaffold, and these PCMs have great potential in solar energy utilization and energy-saving buildings.

Interfacial interaction exhibits important role in determining the performance of polymer composites, especially at high filler content. In this work, illuminated from the braze welding technology that is applied to joint different metals using the welding stick with relatively high plastic deformation ability or high toughness, a new concept of ‘interfacial welding’ was proposed to engineer the strong interfacial interaction of the thermally conductive composites. A commercial elastomer, i.e. anhydride-modified ethylene-based copolymer (AEC), was incorporated into the polyamide 6 (PA6)/carbon nanofibers (CNFs) composites. Due to the presence of the insulating AEC and the stronger interfacial affinity between CNFs and AEC, the ternary PA6/CNF/AEC composite samples showed largely enhanced electrical resistance and comparable thermal conductivity compared with the binary PA6/CNF composite samples. Specifically, largely enhanced fracture toughness was achieved for the ternary composite samples. The concept of ‘interfacial welding’ may be extended to fabricate the other composites with excellent comprehensive performances.

In this work, different contents (10–40 wt%) of poly(butylene succinate) (PBS) were introduced into poly(lactic acid) (PLA) through the common melt compounding processing. The microstructure and morphologies of the blends were investigated through differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD) and scanning electron microscope (SEM). The results showed that the presence of PBS neither induces the crystallization nor enhances the crystallinity of PLA matrix, and completely amorphous PLA was obtained in all samples. PBS exhibited dispersed particles in the PLA matrix and there were clear gaps between components. The hydrophilicity of samples was evaluated by measuring contact angles. The results demonstrated that adding PBS improved the hydrophilicity of samples. The hydrolytic degradation measurements were carried out at 37 °C in alkaline solution. The results showed that the presence of PBS accelerated the hydrolytic degradation of PLA matrix. Specifically, the higher the content of PBS was, the bigger the weight loss per unit area of sample was. The hydrolytic degradation mechanism was then analyzed.

Cocontinuous PLA/EVA (60/40 wt%) blends were filled with reduced graphene oxides (0.1–3 wt%) through the master batches of PLA/rGOs and EVA/rGOs, respectively. The results show that rGOs are located at the interface when the blend nanocomposites were prepared from PLA masterbatch. On the other hand, rGOs are located in EVA component when the blend nanocomposites were prepared from EVA/rGOs materbatch. The underlying mechanism for selective localization of rGOs in PLA/EVA was systematically investigated. First, theoretical prediction indicates the interface energies between two polymer components and rGOs are similar and rGOs prefer to locate at the interface of blend. Therefore, kinetic effects, including interfacial stability of rGOs and viscoelastic properties of polymer, play an important role on the selective localization of rGOs migration. Finally, The electrical resistivity measurements show that nanocomposites with rGOs locating at the interface is endowed much lower resistivity and percolation threshold compared to the blend nanocomposites with rGOs locating at EVA component. POLYM. COMPOS., 2015. © 2015 Society of Plastics Engineers

A small amount of graphene oxide (GO) was introduced into poly(vinylidene fluoride) (PVDF)/carbon nanotube (CNT) composites through solution compounding. The thermal conductivity, crystallization behavior of PVDF matrix, and the dispersion states of CNTs and/or CNT/GO in the PVDF composites were comparatively investigated. The results demonstrated that with the presence of only 1 wt% GO, the PVDF/CNT/GO composites exhibited largely enhanced thermal conductivity compared with the PVDF/CNT composites at the same CNT content. Although the crystallinity of matrix in the PVDF/CNT/GO composites is apparently decreased in comparison with that in the PVDF/CNT composites, a large number of polar γ-form crystallites were induced. The presence of GO facilitated the dispersion of CNTs and the formation of denser CNT/GO network structure in the PVDF matrix. The theoretical simulation further demonstrated the experimental observations. The mechanisms for the largely enhanced thermal conductivity of the PVDF/CNT/GO composites were then analyzed.