Essential work of fracture of low‐filled poly(methyl methacrylate)/starch composites

In this study, poly(methyl methacrylate) (PMMA)/starch composites were prepared by a simple solvent casting method. The morphologies of the PMMA/starch composites were studied by scanning electron microscopy. The intermolecular interaction between PMMA and starch was investigated with Fourier transform infrared spectroscopy. The thermal properties of the PMMA/starch composites were compared with those of the pure PMMA sample. Thermogravimetric analysis showed that the thermal stability increased as the starch content increased in the composites. The biodegradability of the PMMA/starch composites was studied with a soil burial test. The degradability was measured in terms of mechanical strength, which increased as the starch content increased. The essential work of fracture (EWF) of the PMMA/starch composite films was investigated by the application of EWF theory under in‐plane (mode I) conditions, and we found that the toughness, in terms of the EWF of composites, increased compared to that of pure PMMA. The fracture of the composites was also evaluated by ANSYS software, and the results were compared to the experimental output. The increased toughness of these PMMA/starch composites may enable their application in the automobile and packaging industries. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Preparation,structural characterization,and properties of poly(methyl methacrylate)/montmorillonite nanocomposites by bulk polymerization

Poly(methyl methacrylate) (PMMA)/montmorillonite (MMT) nanocomposites were synthesized by a simple technique of a monomer casting method, bulk polymerization. The products were purified by hot acetone extraction and characterized by Fourier transform infrared spectroscopy, X‐ray diffraction (XRD), transmission electron microscopy (TEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), examination of their mechanical properties, and light transmittance testing. Although XRD data did not show any apparent order of the MMT layers in the nanocomposites, TEM revealed parallel MMT layers with interlamellar spacings of an average of 9.8 nm and the presence of remnant multiplets of nonexfoliated layers. Therefore, PMMA chains were intercalated in the galleries of MMT. DSC and TGA traces also corroborated the confinement of the polymer in the inorganic layer by exhibiting the increase of glass‐transition temperatures and mass loss temperatures in the thermogram. Both the thermal stability and the mechanical properties of the products appeared to be substantially enhanced, although the light transmittances were not lost. Also, the materials had excellent mechanical properties. Measurement of the tensile properties of the PMMA/MMT nanocomposites indicated that the tensile modulus increased up to 1013 MPa with the addition of 0.6 wt % MMT, which was about 39% higher than that of the corresponding PMMA; the tensile strength and Charpy notched impact strength increased to 88 MPa and 12.9 kJ/m², respectively. As shown by the aforementioned results, PMMA/MMT nanocomposites may offer new technology and business opportunities. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 348–357, 2005     

Thermal stability and molecular interaction of polyurethane nanocomposites prepared by in situ polymerization with functionalized multiwalled carbon nanotubes

Polyurethane (PU) nanocomposites were prepared through conventional and in situ methods with multiwalled carbon nanotubes (MWNTs) functionalized with poly(ϵ-caprolactone). The thermal degradation and stability of PU–MWNT nanocomposites were investigated with nonisothermal thermogravimetry and were explained in terms of the interaction between MWNTs and PU molecules with Fourier transform infrared spectroscopy. The difference in thermal stability between the conventional and in situ nanocomposites was also compared. The thermal degradation of all the nanocomposite samples took place in two stages and followed a first-order reaction. The degradation temperature of the in situ nanocomposites was higher than that of the conventional nanocomposites with the same loading of MWNTs. The activation energy at 10% degradation and the half-life period were also higher in the in situ nanocomposites compared to the conventional nanocomposites. Such higher thermal stability of the in situ nanocomposites was ascribed to covalent bond formation between MWNTs and PU chains, which could result in better dispersion of MWNTs in the PU matrix for the in situ nanocomposites than for the conventional nanocomposites. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Effect of OMMTs on flame retardancy and thermal stability of poly(ethylene‐co‐vinyl acetate)/LDPE/magnesium hydroxide composites

The aim of this study was to prepare poly (ethylene‐co‐vinyl acetate) (EVA)/ low density polyethylene (LDPE)/magnesium hydroxide (MH) composites applicable in cable industry with required flame retardancy. For this reason, two types of organo‐modified montmorillonites (OMMT) with different surface polarites (Cloisite 15A and Cloisite 30B) at various concentrations, and also combination of these two OMMTs with overall loadings of 2 wt % and 5 wt % were used. The samples were compounded using a twin screw extruder with total (MH + OMMT) feeding of 55 wt % and 60 wt %. Limiting oxygen index (LOI) of the samples containing 2 wt % of OMMTs increased about 16% and dripping was suppressed according to vertical burning test (UL‐94V). Thermogravimetric results of EVA/LDPE/MH samples containing OMMT showed that the beginning of second step degradation was shifted about 50°C to higher temperatures. The composite tensile strength results showed enhancement by incorporating some amount of nanoclays with EVA/LDPE/MH composites. Scanning electron microscopy images confirmed that MH particles had better wetting by EVA matrix in presence of nanoclays. Oxidative induction time of the EVA/LDPE/MH/OMMT nanocomposites was 140 min, which was more than that of the samples without OMMT (20 min). Employing the equal weight ratios of the two OMMTs demonstrated a synergistic effect on flame retardancy of the samples according to the both tests results (LOI, UL‐94V). X‐ray diffraction analysis of the samples confirmed the intercalation/semiexfoliation structure of nanosilicate layers in the bulk of EVA/LDPE matrix. This led to longer elongation at break and thermal stability of Cloisite 15A based nanocomposites. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40452.     

In situ polymerization and photophysical properties of poly(p‐phenylene benzobisoxazole)/multiwalled carbon nanotubes composites

Poly(p‐phenylene benzobisoxazole)/multiwalled carbon nanotubes (PBO‐MWCNT) composites with different MWCNT compositions were prepared through in situ polymerization of PBO in the presence of carboxylated MWCNTs. The nanocomposite's structure, thermal and photophysical properties were investigated and compared with their blend counterparts (PBO/MWCNT) using Fourier transform infrared spectra, Raman spectra, Wide‐angle X‐ray diffraction, thermogravimetric analysis, UV‐vis absorption, and photoluminescence. The results showed that MWCNTs had a strong interaction with PBO through covalent bonding. The incorporation of MWCNTs increased the distance between two neighboring PBO chains and also improved the thermal resistance of PBO. The investigation of UV‐vis absorption and fluorescence emission spectra exhibited that in situ PBO‐MWCNT composites had a stronger absorbance and obvious trend of red‐shift compared with blend PBO/MWCNT composites for all compositions. This behavior can be attributed to the efficient energy transfer through forming conjugated bonding interactions in the PBO‐MWCNT composites. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Poly(vinylidene fluoride)–polyacrylonitrile blend flat‐sheet membranes reinforced with carbon nanotubes for wastewater treatment

In this reported study, poly(vinylidene fluoride) (PVDF) and polyacrylonitrile (PAN) blend flat‐sheet membranes were prepared via a phase‐inversion method with various loadings of multiwalled carbon nanotubes. The effects of the carbon nanotubes (CNTs) on the performance and morphology of the PVDF–PAN composites were investigated via tests of the pure water flux and rejection of bovine serum albumin, scanning electron microscopy, atomic force microscopy, Fourier transform infrared spectroscopy, X‐ray diffraction, thermogravimetric analysis, and contact angle (CA) analysis. The experimental results demonstrate that the CNTs contributed to the improvement of the flux and hydrophilicity of the membranes. The maximum value of the flux was 398.1 L m^?2 h^?1, and the value of CA for the composite membranes was found to be 48°. In addition, the results of the mechanical properties tests illustrate that the brittleness and plasticity of the hybrid membranes were greatly improved by the presence of the CNTs. The flux recovery ratio was maintained at 75%; this demonstrated that the PVDF–PAN membranes enhanced with the CNTs possessed good antifouling performance. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46155.     

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.     

Fabrication of novel polyaniline/flowerlike copper monosulfide composites with enhanced electromagnetic interference shielding effectiveness

Novel polyaniline (PANI)/flowerlike CuS composites with improved electromagnetic interference (EMI) shielding effectiveness (SE) were prepared through the in situ polymerization of PANI into the flowerlike CuS microspheres. X‐ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, ultraviolet–visible optical absorption spectroscopy, thermogravimetric analysis, electrical conductivity testing, and EMI SE testing were used to characterize the as‐obtained products. The results reveal that the flowerlike CuS was uniformly coated by a PANI shell. Most importantly, compared with the original CuS and pure PANI, the novel PANI/flowerlike CuS composites exhibited a remarkably enhanced SE. With a thickness of 3 mm, the optimal EMI SE of the PANI–CuS composites reached ?45.2 dB at 2.78 GHz, and an improved shielding efficiency below ?18 dB was also obtained over the frequency range from 300 kHz to 3 GHz. This suggested that these novel PANI/flowerlike CuS composites have promising applications in the field of shielding materials. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45232.     

Rheological and thermal properties of poly(ethylene oxide)/multiwall carbon nanotube composites

Poly(ethylene oxide) (PEO) based nanocomposites were prepared by the dispersion of multiwall carbon nanotubes (MWCNTs) in aqueous solution. MWCNTs were added up to 4 wt % of the PEO matrix. The dynamic viscoelastic behavior of the PEO/MWCNT nanocomposites was assessed with a strain‐controlled parallel‐plate rheometer. Prominent increases in the shear viscosity and storage modulus of the nanocomposites were found with increasing MWCNT content. Dynamic and isothermal differential scanning calorimetry studies indicated a significant decrease in the crystallization temperature as a result of the incorporation of MWCNTs; these composites can find applications as crystallizable switching components for shape‐memory polymer systems with adjustable switching temperatures. The solid‐state, direct‐current conductivity was also enhanced by the incorporation of MWCNTs. The dispersion level of the MWCNTs was investigated with scanning electron microscopy. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Mechanical and thermal properties of wood fibers reinforced poly(lactic acid)/thermoplasticized starch composites

Thermoplasticized starch (TPS) filled poly(lactic acid) (PLA) blends are usually found to have low mechanical properties due to poor properties of TPS and inadequate adhesion between the TPS and PLA. The purpose of this study was to investigate the reinforcing effect of wood fibers (WF) on the mechanical properties of TPS/PLA blends. In order to improve the compatibility of wood with TPS/PLA blends, maleic anhydride grafted PLA (MA‐g‐PLA) copolymer was synthesized and used. TPS, TPS/PLA blends, and WF reinforced TPS/PLA composites were prepared by twin‐screw extrusion and injection molded. Scanning electron microscope and crystallinity studies indicated thermoplasticity in starch. WF at two different weight proportions, that is, 20% and 40% with respect to TPS content were taken and MA‐g‐PLA at 10% to the total weight was chosen to study the effect on mechanical properties. At 20% WF and 10% MA‐g‐PLA, the tensile strength exhibited 86% improvement and flexural strength exhibited about 106% improvement over TPS/PLA blends. Increasing WF content to 40% further enhanced tensile strength by 128% and flexural strength by 180% with respect to TPS/PLA blends. Thermal behavior of blends and composites was analyzed using dynamic mechanical analysis and thermogravimetric analysis. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46118.     

Effect of flake size on thermal properties of graphene oxide/poly(methyl methacrylate) composites prepared via in situ polymerization

The effect of graphene oxide (GO) flake size on thermal properties of GO/poly(methyl methacrylate) (GO/PMMA) composites prepared via in situ polymerization was investigated. Two styles of GO sheets were synthesized from different sizes of graphite powders by modified Hummers' method and GO/PMMA composites with GO of different sizes were prepared via in situ polymerization. Transmission electron microscopy verified that GO sheets produced from large graphite powders was obviously larger than that from small graphite powders. The similar number of layers and disorder degree of two types of GO sheets were proved by X‐ray diffraction and Raman, respectively. X‐ray diffraction and scanning electron microscopy results of GO/composites proved the homogenous dispersion of both two types of GO sheets in polymer matrix. Dynamic mechanical analysis and thermogravimetric analysis results showed that large GO sheets exhibit better improvement than small GO sheets in thermal properties of the composites. Compared with neat PMMA, the glass transition temperature and decomposition temperature of the composites with large GO sheets (0.20 wt %) were increased by 15.9 and 25.9 °C, respectively. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46290.     

Synthesis and properties of poly(methyl methacrylate)/carbon nanotube composites covalently integrated through in situ radical polymerization

Poly(methyl methacrylate) (PMMA)/single‐walled carbon nanotube (SWNT) composites were synthesized by the grafting of PMMA onto the sidewalls of SWNTs via in situ radical polymerization. The free‐radical initiators were covalently attached to the SWNTs by a well‐known esterification method and confirmed by means of thermogravimetric analysis and Fourier transform infrared spectroscopy. Scanning electron microscopy and transmission electron microscopy were used to image the PMMA–SWNT composites; these images showed the presence of polymer layers on the surfaces of debundled, individual nanotubes. The PMMA–SWNT composites exhibited better solubility in chloroform than the solution‐blended composite materials. On the other hand, compared to the neat PMMA, the PMMA–SWNT nanocomposites displayed a glass‐transition temperature up to 6.0°C higher and a maximum thermal decomposition temperature up to 56.6°C higher. The unique properties of the nanocomposites resulted from the strong interactions between the SWNTs and the PMMA chains. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Preparation and properties of poly(lactic acid)/lignin-modified polyvinyl acetate composites

Poly(lactic acid)(PLA) has good application in the field of packaging because of its good biodegradability, tensile strength, and film-forming properties. However, the disadvantages of high brittleness and high cost limit the wider application of PLA. PLA/lignin-modified polyvinyl acetate (L-PVAc) composites with excellent toughness were prepared by melt blending PLA with modifier L-PVAc. The mechanical properties, thermal properties and morphology of the composites were characterized to evaluate the effect of L-PVAc content on the properties of the composites. The results showed that the introduction of L-PVAc could increase the impact strength, elongation at break, glass transition temperature, melting temperature and the degree of crystallinity of PLA/L-PVAc composites. When the L-PVAc content reached up to 20.0 wt%, the impact strength, elongation at break, glass transition temperature, melting temperature and the degree of crystallinity of the composites were increased by 298.2%, 167.5%, 3.8%, 1.8%, and 78.8%, respectively compared to pure PLA due to the good toughness of PVAc and heterogeneous nucleation of lignin. This research can promote the high-value utilization of lignin and the application of PLA in the fields of clothing, agriculture, medical and hygiene.     

Thermal and optical properties of gelatin/poly(vinyl alcohol) blends

Differential scanning calorimetry, thermogravimetric analysis, X‐ray diffraction, and ultraviolet–visible spectroscopy of gelatin and poly(vinyl alcohol) (PVA) homopolymers and their blended samples were studied. The data revealed that the gelatin and PVA polymers were compatible over the investigated range of compositions; this contributed to the formation of hydrogen‐bonding interaction between their polar groups. The associated enthalpy‐of‐melting transition and thermal stability of the blended samples increased with increasing PVA content. This indicated that the crystalline structure of PVA was not destroyed completely in the blends, which was consistent with the X‐ray diffraction pattern of the 50/50 (wt %/wt %) blended gelatin/PVA sample. The absorption edge and optical band gap for allowed direct transition were determined from ultraviolet–visible spectra. The induced changes in the band structure are elucidated. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Spectroscopic and electrochemical studies on block‐polymer/PMMA blend based composite polymer electrolytes

Poly(methylmethacrylate)(PMMA)/oxymethylene‐linked polyoxyethylene multi‐block polymer(Om‐POE_n, where n represents number of unit  CH₂CH₂O ) blend based composite electrolyte films containing different lithium salt concentration and nanofillers' content are prepared using solvent evaporation technique. The interaction of polymer–salt complex has been confirmed using FTIR spectral studies. The figuration of CPE was studied by XRD. Ionic conductivity and thermal behavior of the CPEs were studied with various salt concentrations, temperature, and nanofillers' content. The surface structure of the CPE is also investigated using scanning electron microscopy. The high room temperature ionic conductivity, transmittivity in the visible region, and thermal stability make these CPEs potential candidates as solid‐like electrolytes for electrochemical devices. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Mechanical properties and thermal stability of poly(L‐lactide)/calcium carbonate composites

Poly(L ‐lactide) (PLA) was melt‐mixed with micrometer‐sized and nanosized calcium carbonate (CaCO₃) particles before and after modification with calcium stearate. Adhesion between the CaCO₃ particles and the PLA matrix was assessed qualitatively by scanning electron microscopy observation of the fractured surface morphology of the composites. The effect of the incorporation of the CaCO₃ particles on the thermal stability of the PLA‐based composites was quantified by the temperatures corresponding to 5 and 50% of weight loss and the activation energy determined through thermogravimetric analyses of the composites. The tensile strength and modulus values of the composite were improved greatly without a significant loss in the elongation at break when the nanosized CaCO₃ was incorporated up to 30 wt %. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis and characterization of poly(methyl methacrylate)/montmorillonite nanocomposites by in situ bulk polymerization

Poly(methyl methacrylate)/montmorillonite (MMT) nanocomposites were prepared by in situ bulk polymerization. The results showed that the silicone coupling agent affected the structure and properties of hybrid materials. XRD analysis showed that the dispersion of clay in nanocomposites with silicone‐modified organophilic MMT was more ordered than that in nanocomposites with unmodified organophilic MMT. The glass transition temperature (T_g) of the nanocomposites was 6–15°C higher and the thermal decomposition temperature (T_d) was 100–120°C higher than those of pure PMMA. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2256–2260, 2003     

Synthesis and characterization of poly(methyl methacrylate)/polysiloxane composites and their coating properties

A series of poly(methyl methacrylate) (PMMA)/polysiloxane composites and their coatings were prepared as designed. A copolymer (PMMAVTEOS) containing methyl methacrylate (MMA) and vinyltriethoxysilane (VTEOS) was prepared by free radical polymerization and then condensed with methyl triethoxysilane (MTES) to fabricate PMMA/polysiloxane composites; their corresponding coatings were obtained via a curing process in an oven (at 75 °C). The polymers were characterized by gel permeation chromatography and Fourier transform infrared spectroscopy. The surface property, hardness, water contact angle, thermal stability, and optical property of the coatings were investigated by scanning electron microscopy, pencil hardness testing, water contact angle testing, thermogravimetric analysis, and ultraviolet–visible spectroscopy, respectively. The results showed that, after addition of MMA, the pencil hardness of the coatings was reduced from 6H to 2H and the thermal stability decreased from 365 to 314 °C. However, it increased the flexibility and adhesion properties (the water contact angle increased from 94.7° to 102.1°). The transparent PMMA/polysiloxane coatings showed excellent scratch resistance, a smooth surface, high thermal stability, and a strong adhesion property. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46358.     

Synthesis and characterization of sulfonated poly(ethylene terephthalate)/montmorillonite nanocomposites

Sulfonated poly(ethylene terephthalate) (SPET)/montmorillonite nanocomposites were prepared by in situ intercalative polymerization. The microstructure, morphology, and properties of the nanocomposites were studied with wide‐angle X‐ray diffraction, transmission electron microscopy, atomic force microscopy, differential scanning calorimetry, and thermogravimetric analysis. The results indicated that an increase in the ? SO₃Na content improved the dispersion of organically modified montmorillonite in the SPET ionomer matrix, and the dispersed layered silicates in the SPET matrix acted as nucleating agents in SPET crystallization processes and improved the thermal stability of SPET. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1150–1156, 2005     

Preparation and properties of poly(methyl methacrylate)/iron carbonate(p) nanocomposites

The mass transport of methanol mixed with ferric chloride hexahydrate (FeCl₃ · 6H₂O) in poly(methyl methacrylate) and poly(methyl methacrylate)/iron carbonate particulate_(p) nanocomposites is prepared by chemical vapor crystallization and the resulting materials, which are subjected to characterization to evaluate thermal and optical properties, have been investigated. Mass transport is an anomalous and endothermic process and satisfies the van't Hoff plot. We have prepared successfully poly(methyl methacrylate)(PMMA)/iron carbonate particulates nanocomposites using CO₂ gas slowly diffused into saturated solvent mixture‐treated poly(methyl methacrylate) for 48 h. After SEM observation, approximately 80 nm iron carbonate particulates were precipitated and evenly distributed in the poly(methyl methacrylate) matrix. In comparison with solvent mixture‐treated PMMA, the cut‐off wavelength of transmittance in nanocomposites shifts to the shorter wavelength side (red shift). The presence of nanoscale iron carbonate particulates increased the glass transition temperature of the nanocomposites as determined by differential scanning calorimeter, and the glass transition temperature increased with increasing content of nanoscale iron carbonate particulates. The FTIR spectra of solvent mixture‐treated poly(methyl methacrylate) and nanocomposites are also studied. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 2329–2338, 2005