Orange peel waste from juicing as raw material for plastic composites intended for use in food packaging

Utilization of orange peel (OP) from the juicing industry as filler material within a polymer matrix can add value to this agricultural waste and reduce dependence on nonrenewable resources. This study aims to investigate the impact of OP filler's physical characteristics including size, loading, and retention/removal of zest on plastic properties of interest for food packaging. Linear low-density polyethylene (LLDPE) is selected to produce plastic composites due to its widespread use in food packaging. Eight different LLDPE/OP sheets from combinations of different OP characteristics are examined. Results show that OP particle sizes of 75–177 μm without zest at 0.4-g loading improve thermal stability, color, dispersion, tensile strength, modulus of elasticity, and elongation at break as well as reduce air bubble formation and OP agglomerate sizes in LLDPE/OP composites. Results show a promise in utilization of OP fillers to produce a composite comparable to neat LLDPE and composites with UV-blocking properties. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48841.     

Enhanced dielectric constant and suppressed electrical conductivity in polymer nanocomposite films via loading MXene/TiO2/MoS2 nanosheets

Conductor/polymer nanocomposites can achieve high dielectric constant with low filler loading, but conductive fillers come into contact with each other easily, resulting in the formation of conductive paths. In this work, MXene/TiO₂/MoS₂ nanosheets were prepared by one-step hydrothermal method, and MXene/TiO₂/MoS₂/poly(vinylidene fluoride-co-hexafluoropropylene) (P(VDF-HFP)) nanocomposite films were prepared by solution casting method. At 1 kHz, with an optimized MXene/TiO₂/MoS₂ nanosheets loading of 8.0 wt%, MXene/TiO₂/MoS₂/P(VDF-HFP) nanocomposite films achieve a high dielectric constant of 944 and maintain a low dielectric loss of 0.19. TiO₂ and MoS₂ semiconductive layers on the surface of MXene nanosheets can prevent the formation of conductive paths, and therefore, nanocomposite films possess suppressed electrical conductivity. Moreover, MXene/TiO₂/MoS₂ nanosheets can build more microcapacitor structures in nanocomposite films with higher filler loading, which further improves the dielectric constant of nanocomposite films. Finite element simulation shows that TiO₂ and MoS₂ semiconductive layers can lower the electric field intensity and polarization intensity at the interface between conductive fillers and polymer matrix. Herein, MXene/TiO₂/MoS₂/P(VDF-HFP) nanocomposite films possess not only excellent dielectric properties, but also excellent mechanical properties, which can be used as flexible dielectric materials in electronic packaging technology.     

Raw and chemically treated bio-waste filled (Limonia acidissima shell powder) vinyl ester composites: Physical,mechanical, moisture absorption properties,and microstructure analysis

The rapid growth of environmentally sustainable and eco-friendly materials tends to the utilization of biowastes as filler in polymer matrix composites. The particulate composite with improved wettability of fillers and advanced approach can evolve polymer composites that exhibit promising applications in packaging, automobile, marine, construction, and aerospace. In the present work, one of the biowaste fillers were synthesized from Limonia acidissima shells via a top-down approach (pulverizing) and the surfaces were chemically modified using sodium hydroxide (NaOH) before they were used as fillers in vinyl ester polymer composites by different weight percentage (0, 5, 10, 15, and 20 wt%). The prepared particulate composites were characterized by mechanical properties, moisture absorption behavior, and morphology. At different filler loading the tensile strength, tensile modulus, flexural strength, flexural modulus, impact strength, hardness, density, and moisture intake tests were performed. The results reveal that the properties increased for composites filled with alkaline treated fillers for the same filler loading and found to be higher at filler loading of 15 wt%. The morphological analysis confirms the better interfacial bonding between alkali-treated particles and matrix due to the removal of non-cellulose materials from the surface of the particles.     

Isotactic polypropylene metal oxide and silica nanocomposites by a two‐step process comprising in situ olefin polymerization and melt compounding

Nanocomposites of isotactic polypropylene (iPP) with 0.5 wt% filler of MgO@Mg(OH)₂ (35 nm) or silicon dioxide (20–60 nm) or barium titanate (50 nm) nanoparticles were obtained from melt compounding of filler masterbatches with commercial iPP. The masterbatches with 5 wt% nanofiller were prepared in an in situ polymerization procedure using a metallocene/methylaluminoxane (MAO) catalyst system that was supported on the respective oxides. The original agglomerates of the nanoparticles were broken up by treatment with dibutylmagnesium for MgO@Mg(OH)₂, and with ultrasound in the presence of MAO for SiO₂ and BaTiO₃. The tacticity (98% mmmm) of the in situ formed PP was not influenced by the presence of the nanofillers. Scanning electron microscopy and energy‐dispersive X‐ray spectroscopy mapping show a fine dispersion of single particles and small clouds or clusters. The primary nanoparticles appear to be surrounded by polymer. The elongation at break was decreased to 50, 17 and 9% for MgO@Mg(OH)₂), SiO₂ and BaTiO₃, respectively. After melt compounding with iPP, a homogeneous single‐particle distribution of the oxidic nanoparticles was found in the resulting composites with 0.5 wt% filler content. © 2019 Society of Chemical Industry     

Application of poly (amide-<Emphasis Type="Italic">b</Emphasis>-ethylene oxide)/zeolitic imidazolate framework nanocomposite membrane in gas separation

Mixed matrix membranes (MMMs) are gaining increasing interest in academic and industrial research due to their combined, desirable properties of both polymers and organic/inorganic filler as important materials. In this work, synthesized zeolitic imidazolate framework (ZIF-8) suspension (10–50 wt%) was directly incorporated into a [poly (amide-b-ethylene oxide) Pebax^® 1657] matrix in order to improve the gas separation performance of the membrane. Dynamic light scattering (DLS) analysis showed an average diameter of 77.4 nm for the prepared nanoparticles. The transparent membranes were characterized by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) spectroscopy, and X-ray diffractometry (XRD). These indicated excellent dispersion of nanoparticles, which was achieved by ultrasonication before casting the solution. Incorporation of ZIF-8 as filler in the polymer matrix led to improved thermal and mechanical stability of the membranes. This was confirmed by TGA and tensile analyses, indicating good contacts provided at the polymer/filler interfaces. The effect of ZIF-8 loading (up to 50 wt%) on membrane performance was investigated and it showed an optimum loading of 30 %. Single gas (CO₂, N₂ and CH₄) permeation tests revealed rapid, enhanced permeability of the nanocomposite membranes without significant changes in selectivity (compared to those of the pristine polymeric membrane). The permeability increases for CO₂, CH₄ and N₂ in the optimum Pebax^® 1657/ZIF-8 (30 wt%) membrane were found in the stated order as 111, 88 and 99 %. The study revealed that Pebax^® 1657/ZIF-8 membranes displayed better gas permeation properties compared to those of Pebax^® 1657.     

Study of matrix–filler interaction through correlations between structural and viscoelastic properties of carbonous-filler/polymer-matrix composites

Polymer matrix composites reinforced with carbonous fillers are of significant commercial importance thanks to their vast application base. As the performance of such composites largely depends on matrix–filler interaction, the present study is focused on the impact of surface chemical states of polymer matrix and carbonous filler on the viscoelastic performance of the composites. Here we report investigation of the filler–matrix interface through spectroscopic techniques such as X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. Viscoelastic properties of various polymer matrix composites prepared by varying the filler volume fraction and/or the matrix/filler type have been studied through dynamic mechanical thermal analysis. Further, to understand the matrix–filler interaction, correlations between viscoelastic parameters and various structural parameters such as the surface area of filler and the surface chemical states of filler/matrix obtained through XPS have been studied. Strong correlations between the viscoelastic parameters and the matrix/filler surface chemical states have been observed, suggesting the XPS as an important tool to study the role of the surface functionalities present on the matrix/filler surface to define the matrix–filler interaction. The filler surface functionalities such as C bound O have been found more compatible with the polymers having aromatic ring in the repeat unit. © 2020 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 137, 48660.     

Enhanced Thermo‐Mechanical Stiffness,Thermal Stability,and Fire Retardant Performance of Surface‐Modified 2D MoS2 Nanosheet‐Reinforced Polyurethane Composites

This article reports new‐generation 2D‐MoS₂ nanosheet‐containing polyurethane (PU) composite materials with improved thermo‐mechanical stiffness, thermal stability, and fire retardation properties. The surface of 2D‐MoS₂ nanosheets is modified with melamine (M‐MoS₂), and then PU composites with varying M‐MoS₂ loadings are synthesized using an in situ polymerization method. During polymerization, 3‐amino‐propyl‐trimethoxy silane is introduced to create silicate functionality on the PU chains, which further improves the compatibility between PU and M‐MoS₂. Microscopy studies confirm the distribution of highly intercalated and agglomerated M‐MoS₂ nanosheets in the PU matrix. The PU composite containing 5 wt% M‐MoS₂ shows a 65% higher storage modulus (at 30 °C) than that of pure PU. The thermal stability of pure PU is significantly improved (62 °C) after composite formation. Thermogravimetric analysis in combination with FTIR spectroscopy shows that the PU/M‐MoS₂ composites release less toxic gases during thermal degradation compared to pure PU. Moreover, the composite containing 5 wt% M‐MoS₂ shows improved fire retardation properties, with 45% and 67.5% decrease in the peak heat and total heat release rates, respectively, as compared with those of pure PU. In summary, 2D‐MoS₂ is shown to have potential as an advanced nano‐filler to obtain stiffer PU composite with improved fire retardant property for structural application.     

Dynamic rheology and morphology of HDPE‐fumed silica composites: Effect of interface modification

In the present study, high density polyethylene (HDPE)‐based composites containing different amounts of fumed silica (FS) were prepared by melt compounding in a corotating twin screw extruder. Polyethylene‐g‐maleic anhydride copolymer (PE‐g‐MA) containing 1 wt% maleic anhydride was used for interface modification between filler and polymer. The interaction between the surface hydroxyl groups of fumed silica nanoparticles with maleic anhydride groups of PE‐g‐MA led to a finer dispersion of the filler in the HDPE matrix. The terminal complex viscosity and terminal storage modulus were highest at 1 wt% filler loading due to widely spread network formation by FS nanoparticles. This filler network plausibly got disturbed at higher filler content and/or interface modification which was reflected in their stress relaxation behavior also. The dynamic rheological behavior of the composites was explained in terms of morphological observations. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers     

Polycarbonate/molybdenum disulfide/carbon black composites: Physicomechanical,thermal, wear,and morphological properties

To investigate the influence of molybdenum disulfide (MoS₂) as solid lubricant and filler on the polycarbonate (PC) and carbon black (CB) composites, PC containing one weight percentage of CB powder was compounded and extruded with 0.5, 1.0, 2.0, and 3.0 weight percentage of MoS₂ powder in a co‐rotating twin screw extruder. Thus, the fabricated PC/CB/MoS₂ composites were characterized for physicomechanical properties such as density, void content, surface hardness, tensile behaviors, and impact strength. The thermal characteristics of the composites have been studied by differential scanning calorimetry and dynamic mechanical analysis (DMA). The effect of MoS₂ content, loads and sliding distances on wear characteristics of the composites were evaluated using pin‐on‐disc equipment. It was found that wear, friction, and laser etching resistance of PC/CB/MoS₂ composites increased with increase in MoS₂ content along with improvement in tensile and impact strengths. DMA analysis indicates the storage modulus of PC/CB/MoS₂ composites increased with increase in MoS₂ content below the glass transition temperature (T_g) of PC. Worn surfaces and laser etched surfaces were examined with scanning electron microscopy and optical microcopy respectively to have better insight of the wear and laser etching mechanism. It was observed that the MoS₂ as solid lubricant played major role in improving resistance to wear, friction, and laser etching. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

BaTiO3 nanocubes-Gelatin composites for piezoelectric harvesting: Modeling and experimental study

Flexible composites containing BaTiO₃ nanoparticles into Gelatin bio-polymer matrix were designed and investigated. Following the idea that the electric field concentration in corners/edges at the interfaces between dissimilar materials give rise to enhanced effective permittivity in composites, cuboid-like BaTiO₃ nanoparticles have been employed as nanofillers into Gelatin matrix by using an inexpensive solution-based processing method. As predicted by finite element method simulations developed for cubic-like inclusions into a homogeneous polymer matrix, the experimental permittivity of xBT-(1-x)Gelatin composites increases when increasing the high-permittivity filler addition. For the composition x = 40 wt% (corresponding to 12 vol% BaTiO₃ addition), permittivity reaches ε_r ～15.7 with respect to ε_r ～9.8 of pure Gelatine (measured at 10⁵ Hz), while the average piezoelectric coefficient d₃₃ as determined by piezoelectric force microscopy shows a remarkable increase up to 21 pm/V in composites with x = 40 wt%, in comparison to ～7 pm/V in pure Gelatin. By using the experimentally determined material constants, the simulated piezoelectric voltage output vs. time has shown a similar increase (about a doubling of its amplitude) of the harvesting signal in the composite with x = 40 wt% BT, with respect to one of the polymer matrix, thus demonstrating the beneficial role of embedding BT nanoparticles into the biopolymer for increasing the mechanical harvesting response.     

Poly(arylene ether nitrile) ternary dielectric composites modulated via polydopamine-assisted BaTiO3 decorating MoS2 sheets

Flexible, high-k and thermostability polymer-based dielectric composites are the core components in electrostatic capacitors and embedded devices. Herein, the dielectric polymer matrix composites are developed by embedding polydopamine (PDA)-encapsulated hydroxylated barium titanate (BTH) and molybdenum disulfide (MoS₂) into poly(arylene ether nitrile) (PEN) matrix. The MoS₂/PDA@BTH-1 particles served as fillers are prepared by polydopamine deposition technology assisted with hydrogen bonding interactions. The introduction of PDA intermediate layer contributes to the construction of multiple interfaces and nanocapacitor networks, enhancing interfacial polarization. Based on this, the resulted dielectric composite with 15 wt% MoS₂/PDA@BTH-1 loading exhibits the dielectric constant of 17.3 at 1 kHz, higher than that of 4.2 of PEN, while can maintain relatively low dielectric loss simultaneously. The possible mechanisms and synergistic enhancement effect of MoS₂/PDA@BTH-1 particles on the dielectric properties of composites are also proposed. The results of permittivity-temperature stability show that the dielectric constant of PEN-based dielectric composites is stable when reaches 158 °C, indicating that the film can be used in capacitor at temperatures up to 150 °C, higher than that of most polymer capacitors. All in all, a feasible pathway is provided to design PEN-based dielectric composites with high-k to adopt the high-temperature environment in electrostatic capacitors and embedded devices.     

Mechanical and tribological properties of nitrile rubber filled with modified molybdenum disulphide

In this work, cetyl trimethyl ammonium bromide (CTAB), silane coupling agent (KH570) and polyethylene glycol (PEG) were used to modify the surface property of molybdenum disulphide (MoS₂). MoS₂/nitrile rubber (NBR) composites were directly prepared by mechanical blending. Meanwhile, the effects of loading content of MoS₂, the kinds of modifiers on the mechanical and tribological properties of the composites were evaluated. The dispersion of fillers in rubber matrix and the worn surface of the composites were analysed by SEM. Results showed that the properties of MoS₂/NBR composites prepared by CTAB modified MoS₂ were superior to that of KH570 or PEG modified MoS₂ and unmodified MoS₂ because of strong opposite charges attraction between cetyl trimethyl ammonium cation and MoS₂ surface. When adding 10?phr CTAB modified MoS₂ in rubber matrix, the dispersion of filler was optimum, and the coefficient of friction of composite was the lowest in the prepared composites.     

Different filler effect of carbon nanotube and graphene nanoplatelet in the poly(arylene ether nitrile) matrix

The different filler effects of identical nitrile‐functionalized carbon nanotubes (CNTs) and graphene nanoplatelets (GNs) in a poly(arylene ether nitrile) (PEEN) matrix were investigated. PEEN/CNT and PEEN/GN composites were prepared by a facile solution‐casting method and systematically investigated for their differences in morphological, thermal and rheological properties. In the PEEN matrix GNs contact one another in a plane‐to‐plane manner, while CNTs are separated. Compared with PEEN/CNT composites, PEEN/GN composites below 2 wt% filler content exhibited higher thermal stability. Rheological properties of the resulting composites indicated that PEEN/GN composites were more sensitive to strain and exhibited higher η*, G′ and G″ than PEEN/CNT composites. The rheological percolation for CNTs is over 2 wt%, higher than that for GNs (around 1 wt%). All these differences originate from the different dimensions and structures of CNTs and GNs: GNs with a flake‐like structure and larger surface area can have stronger physical and interfacial interactions with the polymer matrix. This work gives a comparative view of the different filler effects that functionalized CNTs and GNs can have in the polymer host. With identical processing technology, GNs can show a stronger filler effect than CNTs. © 2012 Society of Chemical Industry     

Thermal,electrical, and mechanical properties of Si3N4 filled LLDPE composite

Silicon nitride (Si₃N₄) filled linear low-density polyethylene (LLDPE) composite was prepared. The effects of Si₃N₄ filler content, dispersion, and LLDPE particle size on the thermal conductivity, and Si₃N₄ filled content on the mechanical and electrical properties of Si₃N₄ reinforced LLDPE composites prepared using powder mixing were investigated. The results indicate that there existed a unique dispersion state of Si₃N₄ particles in LLDPE, shell-kernel structure, in which Si₃N₄ particles surrounded LLDPE matrix particles. With increasing filler content and LLDPE particles size, thermal conductivity increased, and reached 1.42 W/m K at 30 vol% of filler, seven times as that of unfilled LLDPE. Furthermore, the examinations of Agari model demonstrate that larger size LLDPE particles form thermal conductive networks easily compared with smaller ones. The values predicted by theoretical model underestimate the thermal conductivity of Si₃N₄/LLDPE composites. In addition, the composites still possessed rather higher electrical resistivity and dielectric properties, but the mechanical properties decreased. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

Percolation phenomena in polymers containing dispersed iron

Metal‐polymer composites based on polyethylene (PE), polyoxymethylene (POM), polyamide (PA) and a PE/POM blend as matrix and dispersed iron (Fe) as filler have been prepared by extrusion of the appropriate mechanical mixtures, and their electrical conductivity, dielectric properties and thermal conductivity have been investigated. The filler spatial distribution is random in the PE‐Fe, POM‐Fe and PA‐Fe composites. In the PE/POM‐Fe composite the polymer matrix is two‐phase and the filler is contained only in the POM phase, resulting in an ordered distribution of dispersed Fe in the volume of polymer blend. The transition through the percolation threshold ?_c is accompanied by a sharp increase of the values of conductivity σ, dielectric constant ε′ and dielectric loss tangent tan δ. The critical indexes of the equations of the percolation theory are close to the theoretical ones in the PE‐Fe and POM‐Fe composites, whereas they take unusually high values in the PE/POMFe composite. Thus, t in the equation σ ～ (φ – φ_c)^t is 2.9–3.0 in the systems characterized by random distribution of dispersed filler and 8.0 in the PE/POM‐Fe system. The percolation threshold φ_c depends on the kind of polymer matrix, becoming 0.21, 0.24, 0.29 and 0.09 for the composites based on PE, POM, PA and PE/POM, respectively. Also the thermal parameters of the PE/POM‐Fe composite are different from those of all other composites. A model explaining the unusual electrical characteristics of the composite based on the polymer blend (PE/POM‐Fe) is proposed, in agreement with the results of optical microscopy.     

Fabrication,characterization, and properties of poly(ethylene‐co‐vinyl acetate)/magnetite nanocomposites

Poly(ethylene‐co‐vinyl acetate) (EVA)/magnetite (Fe₃O₄) nanocomposite was prepared with different loading of Fe₃O₄ nanoparticles. The mixing and compounding were carried out on a two‐roll mixing mill and the sheets were prepared in a compression‐molding machine. The effect of loading of nanoparticles in EVA was investigated thoroughly by different characterization technique such as transmission electron microscopy (TEM), X‐ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), limiting oxygen index (LOI), and technological properties. TEM analysis showed the uniform dispersion of filler in the polymer matrix and the dispersion of filler decreased with increase in filler content. XRD of the nanocomposite revealed the more ordered structure of the polymer chain. An appreciable increase in glass transition temperature was observed owing to the restricted mobility of Fe₃O₄‐filled EVA nanocomposite. TGA and flame resistance studies indicated that the composites attain better thermal and flame resistance than EVA owing to the interaction of filler and polymer segments. Mechanical properties such as tensile strength, tear resistance, and modulus were increased for composites up to 7 phr of filler, which is presumably owing to aggregation of Fe₃O₄ nanoparticle at higher loading. The presence of Fe₃O₄ nanoparticles in the polymer matrix reduced the elongation at break and impact strength while improved hardness of the composite than unfilled EVA. The change in technological properties had been correlated with the variation of polymer–filler interaction estimated from the swelling behavior. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40116.     

Graphene/nanorubber reinforced electrically conductive epoxy composites with enhanced toughness

Graphene platelets (electrically conductive 2D filler) and rubber nanoparticles (0D soft filler) can work together to develop electrically conductive and toughened epoxy composite adhesives. In this study, complementing effect between graphene platelets (GnPs) and rubber nanoparticles (RnPs) within an epoxy matrix is reported. In the 3-phase composite adhesive, the 2D graphene platelets form global conductive network and rubber nanoparticles provide a viscoelastic phase inside the epoxy, both complementing each other to develop electrically conductive and toughened epoxy composite adhesives. Fracture toughness (K_1c) and critical strain energy release rate (G_1c) of the epoxy were augmented by 422% and 872%, respectively by adding 1 wt% RnPs and it recorded electrical percolation threshold at 0.78 vol% GnP. Also, the Young's modulus and strength of epoxy/1 wt% RnP composite were promoted from 1.57 to 2.32 GPa when 1 wt% GnP is added. Scanning electron microscopy analysis was conducted to investigate the toughening mechanism of epoxy/RnP/GnP and epoxy/GnP composites. Lap shear strength tests on epoxy composite adhesives confirm the reinforcement effect of GnPs and toughness effect of RnPs.     

Structural,thermal, and gas transport properties of HDPE/LLDPE blend‐based nanocomposites using a mixture of HDPE‐g‐MA and LLDPE‐g‐MA as compatibilizer

Nanocomposites based on high density polyethylene (HDPE)/linear low density polyethylene (LLDPE) blend were prepared by melt compounding in a twin‐screw extruder using organoclay (montmorillonite) as nano‐filler and a 50/50 wt% mixture of maleic anhydride functionalized high density polyethylene (HDPE‐g‐MA) and linear low density polyethylene (LLDPE‐g‐MA) as the compatibilizing system. The addition of a maleated polyethylene‐based compatibilizing system was required to improve the organoclay dispersion in the HDPE/LLDPE blend‐based nanocomposite. In this work, the relationships between thermal properties, gas transport properties, and morphology were correlated. The compatibilized nanocomposite exhibited an intercalated morphology with a small number of individual platelets dispersed in the HDPE/LLDPE matrix, leading to an significant decrease in the oxygen permeation coefficient of the nanocomposites. A decrease in the carbon dioxide permeability and oxygen permeability with increase of nanoclay was observed for the compatibilized nanocomposites. The carbon dioxide permeability of the compatibilized nanocomposites was lower than the carbon dioxide permeability of the uncompatibilized nanocomposites even with the low intrinsic barrier properties of the compatibilizer. These effects were attributed to a good dispersion of the inorganic filler, good wettability of the filler by the polymer matrix, and strong interactions at the interface that increased the tortuous path for diffusion. Theoretical permeability models were used to estimate the final aspect ratio of nanoclay in the nanocomposite and showed good agreement with the aspect ratio obtained directly from TEM images. POLYM. ENG. SCI., 56:765–775, 2016. © 2016 Society of Plastics Engineers     

Preparation of polyvinyl alcohol/two-dimensional transition metal dichalcogenides composites by high-pressure homogenization

In this article, water-soluble polymer polyvinyl alcohol solution was used to exfoliate the graphene-like two-dimensional materials (MoS₂ and WS₂). The concentrations of the two disulfide nanosheets were 0.092 and 0.087 mg/mL in the 10% aqueous solution of PVA. UV–Vis and Raman spectrum demonstrated that the two dispersions were the few layer nanosheets in the solution. Then, taking the exfoliated WS₂ as filler, a series of PVA/WS₂ composites showing the pale yellow transparent films were prepared by solution process method. Composite films showed good thermal performance. When 1 wt% were added in the PVA matrix, the T_90% improved 44 °C in the air. Furthermore, the three kinds of characteristic temperature of T_10%, T_50%, and T_90% had obvious increase in the N₂. The main reason may be the physical barrier of the 2D nanosheets and the strong interaction force of the S atom of exfoliated 2D nanosheets. The composites could slow the thermal decomposition. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48487.     

Effect of filler functional groups on the mechanical properties and relevant mechanisms of polydicyclopentadiene nanocomposites

Filler functionlizetion is an important strategy to enhance the mechanical properties of polymer composites via the realization of polymer/filler coexists compatibly, interfacial bonding and efficacious load transfer between matrix and filler. In this study, to realize the tailored mechanical properties of polydicyclopentadiene (PDCPD) and to gain insight into the effect of functional groups on their properties, functionalized silica (f-SiO₂) with different functional groups is prepared and combined with PDCPD to produce composites. Compared with neat PDCPD, the yield strength of the composite with 0.20 wt% vinyl-SiO₂ decreases and the impact toughness enhances limitedly, whereas the tensile ductility improves by 16 times. For the case with 0.20 wt% phenyl-SiO₂, it is interestingly observed that the yield strength reinforces by 45.3% and the impact toughness increases remarkably by 222.8%. For the case containing 0.20 wt% ethyl-SiO₂, simultaneous promotion in terms of strength and toughness is achieved. More importantly, the reinforcing/toughening and reaction mechanisms of f-SiO₂/PDCPD composites are explored.