Fracture toughness evaluation of K resin® grafted with maleic anhydride‐ compatibilized polyamide 6/K resin® blends

The mechanical behavior and fracture toughness of polyamide 6 (PA6)/K resin^® (K) blends, with and without maleic anhydride‐grafted K resin^® (K‐g‐MAH) incorporated, have been investigated. The results showed that the tensile strength, elongation at break and impact strength of PA6/K blends were improved considerably on incorporating K‐g‐MAH. This results from the improvement of compatibility between the PA6 and K phases. The essential work of fracture (EWF) method was employed to determine the fracture toughness of PA6/K blends with and without K‐g‐MAH incorporated. The effect of composition on the EWF parameters of the blends was particularly investigated. The results showed that a significant improvement in the specific EWF (w_e) of PA6/K blends occurred when K‐g‐MAH was incorporated. The effect of K‐g‐MAH content on the fracture toughness of the PA6/K/K‐g‐MAH blends was mainly achieved through its influence on the specific essential and nonessential work of fracture in the yielding process. Copyright © 2007 Society of Chemical Industry     

Characterization and properties of sPS/PET/SsPS‐K engineering plastic alloys

The compatibility, crystallization behavior, and mechanical properties of syndiotactic polystyrene (sPS)/polyester (PET)/potassium salt of sulfonated syndiotactic polystyrene (SsPS‐K) were investigated. DMA results showed that all the alloys showed one T_g and the half‐peak width of the sPS/PET/SsPS‐K alloys became narrower compared with that of sPS/PET alloys, which decreased with an increasing content of the SsPS‐K ionomer. The results of DSC showed that the T_m of sPS and PET of the alloys was similar to those of the pure materials and did not change with the content of the SsPS‐K ionomer, while the initial crystallization temperature (T₀) and crystallization temperature at peak (T_p) increased. The crystallization velocity of PET increased with an increasing content of SsPS‐K. The TMA results showed that the alloys could retain the perfect heat proof property of sPS. SEM micrographs showed that the addition of SsPS‐K could reduce the PET domain dimension and enhance the adhesion between the PET domains and the matrix. With an increasing content of SsPS‐K, the PET domain dimension was reduced continuously and dispersed more evenly. The ternary alloys had better mechanical properties and significantly higher unnotched Izod impact strength than those of the alloys without SsPS‐K. When the weight ratio of sPS/PET/SsPS‐K was 85/15/4, the impact strength reached a maximum of 11.5 kJ/m², which was about three times that of pure sPS, and still had a higher tensile strength, flexural strength, and storage modulus, which were 38.8, 54.2, and 1.55 × 10⁴ MPa, respectively. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 656–661, 2002     

Morphology and mechanical properties of polyamide‐6/K resin blends

Mechanical properties and morphological studies of compatibilized blends of polyamide‐6 (PA‐6)/K resin grafted with maleic anhydride (K‐g‐MAH) and PA‐6/K resin/K‐g‐MAH were investigated as functions of K resin/K‐g‐MAH and dispersed phase K resin concentrations, and all the blends were prepared using twin screw extruder followed by injection molding. Scanning electron microscopy (SEM) were used to assess the fracture surface morphology and the dispersion of the K resin in PA‐6 continuous phase, the results showing extensive deformation in presence of K‐g‐MAH, whereas, uncompatibilized PA‐6/K resin blends show dislodging of K resin domains from the PA‐6 matrix. Dynamic mechanical thermal analysis (DMTA) test reveals the partially miscibility of PA‐6 with K‐g‐MAH, and differential scanning calorimetry (DSC) results further identified that the introduction of K‐g‐MAH greatly improved the miscibility between PA‐6 and K resin. The mechanical properties of PA‐6/K resin blends and K‐g‐MAH were studied through bending, tensile, and impact properties. The Izod notch impact strength of PA‐6/K‐g‐MAH blends increase with the addition of K‐g‐MAH, when the K‐g‐MAH content adds up to 20 wt %, the impact strength is as more than 6.2 times as pure PA‐6, and accompanied with small decrease in the tensile and bending strength less than 12.9% and 17.5%, respectively. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Heterogeneous Catalyst of Mixed K Compounds/Ca‐Al‐Graphite Oxide for the Transesterification of Soybean Oil to Biodiesel

A novel heterogeneous solid base catalyst was prepared by loading of Ca‐Al‐graphite oxide with mixed potassium salts and applied in the transesterification of soybean oil with methanol to produce biodiesel. The catalysts were characterized by Hammett indicators, X‐ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, energy dispersive X‐ray spectrometry, and transmission electron microscopy. The effects of the methanol‐to‐oil molar ratio, catalyst amount, reaction temperature, stirring rate, and reaction time were investigated to optimize the transesterification reaction conditions. Moreover, the prepared catalyst retains its activity after being used for four cycles. In particular, the solid base catalyst can be effectively and easily separated from the reaction system, which may provide significant benefits for the development of an environmentally benign and continuous process for preparing biodiesel.     

Seed‐Free Solid‐State Growth of Large Lead‐Free Piezoelectric Single Crystals: (Na1/2K1/2)NbO3

Large Na_0.5K_0.5NbO₃ (NKN) piezoelectric single crystals were obtained by seed‐free solid‐state crystal growth method, which is a traditional sintering grain growth process, with LiBiO₃ used as a sintering aid. The largest dimension of the single crystals obtained was 11 mm × 9 mm × 3 mm. In addition to the LiBiO₃ doping content, temperature, and time effect of the crystal growth process was systematically investigated and considered from the kinetics point of view. With the assistance of Avrami analysis, parameters relevant to the crystal growth process were determined. Laue diffraction and transmission electron microscopy suggested an orthorhombic symmetry for the single crystalline structure. Dielectric‐frequency‐temperature measurements revealed an orthorhombic‐tetragonal and tetragonal‐cubic phase transition at 155°C and 405°C, respectively, both of which are typical of first‐order transitions, and have a well‐defined thermal hysteresis. Rayleigh analysis was performed regarding to the extrinsic reversible and nonreversible piezoelectric properties, and the result suggested a dominant intrinsic reversible piezoelectric contribution of 91.5% under E₀ = 1 kV/cm AC amplitude. Such a single crystal growth process route is low cost and a relative simple preparation process.     

Microstructured Al‐fiber@meso‐Al2O3@Fe‐Mn‐K Fischer–Tropsch catalyst for lower olefins

A thin‐sheet Al‐fiber@meso‐Al₂O₃@Fe‐Mn‐K catalyst is developed for the mass/heat‐transfer limited Fischer–Tropsch synthesis to lower olefins (FTO), delivering a high iron time yield of 206.9 µmol_CO s^?1 at 90% CO conversion with 40% selectivity to C₂‐C₄ olefins under optimal reaction conditions (350°C, 4.0 MPa, 10,000 mL/(g·h)). A microfibrous structure consisting of 10 vol % 60‐µm Al‐fiber and 90 vol % voidage undergoes a steam‐only‐oxidation and calcination to create 0.6 µm mesoporous γ‐Al₂O₃ shell along with the Al‐fiber core. Active components of Fe and Mn as well as additives (K, Mg, or Zr) are then placed into the pore surface of γ‐Al₂O₃ shell of the Al‐fiber@meso‐Al₂O₃ composite by incipient wetness impregnation method. Neither Mg‐modified nor Zr‐modified structured catalyst yields better FTO results than K‐modified one, because of their lower reducibility, poorer carbonization property, and fewer basicity. The favorable heat/mass‐transfer characteristics of this new approach are also discussed. © 2015 American Institute of Chemical Engineers AIChE J, 62: 742–752, 2016     

Activated Carbon‐Supported Mo‐Co‐K Sulfide Catalysts for Synthesizing Higher Alcohols from CO2

Activated carbon‐supported Mo‐Co‐K sulfide catalysts, prepared by stepwise impregnation, were used in the synthesis of higher alcohols via CO₂ hydrogenation. The catalysts with varying Mo contents and defined K/Mo and Co/Mo molar ratios exhibited relatively high CO₂ conversions and high selectivity to total alcohols and C₂₊ alcohols. Moreover, the influence of calcination conditions on the sulfidation states and catalytic performance was studied. The surface sulfur runoff of the supported catalysts can be effectively suppressed by online calcination. As a result, the selectivity to total alcohols and C₂₊ alcohols can be improved.     

Free‐radical terpolymerization of n‐butyl acrylate/butyl methacrylate/d‐limonene

d ‐Limonene (Lim) is a renewable monoterpene derived from citrus fruit peels. We investigated it for use as part of a more sustainable polymer formulation. The bulk free‐radical terpolymerization of n‐butyl acrylate (BA)/butyl methacrylate (BMA)/Lim was carried out at 80°C with benzoyl peroxide as the initiator. The terpolymerization was studied at various initial BA/BMA/Lim molar ratios, and the products were characterized for conversion, terpolymer composition, molecular weight, and glass‐transition temperature. Lim was observed to undergo a significant degradative chain‐transfer reaction, which greatly influenced the polymerization kinetics. The rate of polymerization, final conversion, and polymer molecular weight were all significantly reduced because of the presence of Lim. Nonetheless, polymers with relatively high weight‐average molecular weights (20,000–120,000 Da) were produced. The terpolymer composition was well predicted with the reactivity ratios estimated for each of the three copolymer subsystems. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42821.     

Photoluminescence Properties of Er/Pr‐Doped K0.5Na0.5NbO3 Ferroelectric Ceramics

Er/Pr‐doped K_0.5Na_0.5NbO₃ ceramics have been fabricated and the effects of Pr³⁺ on their photoluminescence properties have been investigated systematically. The visible upconversion emissions, near‐infrared and mid‐infrared downconversion emissions of Er³⁺ ions under the excitation of 980 nm have been studied in detail. The effects of Pr³⁺ on PL properties and energy‐transfer processes have also been elucidated. By selecting an appropriate excitation source, simultaneous visible downconversion emissions of Er³⁺ and Pr³⁺ ions can be realized, and the emission colors of the ceramics can be tuned via the concentration of Pr³⁺ ions in a wide range from yellowish green to yellow. Our results also reveal that the photoluminescence emissions of the ceramics can be enhanced by the alignment of polarization of the ferroelectric host.     

Preparation and characterization of chitosan/montmorillonite‐K10 nanocomposites films for food packaging applications

Chitosan (CS)/montmorillonite‐K10 (MMTK‐10) clay composite films with different amounts of the clay MMTK‐10 (0.5, 1, 2.5, and 5%) were prepared using a solution‐casting method, and their properties were determined. The objective of this study is to prepare CS/clay nanocomposites and then to investigate the effects of clay content on mechanical, barrier, and thermal properties of these nanocomposites. The prepared films were characterized by Fourier transform infrared spectroscopy, X‐ray diffraction analysis, transmission electron microscopy, and scanning electron microscopy. Barrier properties (oxygen and water permeability), mechanical properties (tensile strength and elongation), and thermal behaviors (thermogravimetric analysis) were investigated and compared. The water vapor and gas permeability values of the composite films decreased significantly with increasing filler concentration. Tensile strength of the composites increased significantly with the addition of clay, and elongation at break decreased with increasing clay concentration. The tensile strength of nanocomposites is up to 34.82 MPa for 5 wt% clay content, and the tensile modulus shows a 74.63% higher value than that of neat CS. The resulting films had an opaque appearance, which depended on the amount of MMTK‐10 added. The oxygen permeability decreased with the increase in MMTK‐10. The minimum oxygen permeability (1.54 cm³/m² day atm) was recorded for film with 5% MMTK‐10. The water permeability of the composite films decreased significantly between 13 and 22% when clay was added. The dispersed clay improves the thermal stability and enhances the hardness and elastic modulus of the matrix systematically with the increased loading of clay. POLYM. COMPOS., 33:1874–1882, 2012. © 2012 Society of Plastics Engineers     

Properties of polycarbonate/acrylonitrile‐butadiene‐styrene/talc composites

The morphology, tensile, impact properties, and thermal expansion behavior of polycarbonate (PC)/acrylonitrile‐styrene‐butadiene (ABS)/talc composites with different compositions and mixing sequences were investigated. From the studies of morphology of the PC/ABS/talc composites, it was observed that some talc particles were located in both the PC and the ABS phases of the blend but most were at the interface between the PC and ABS phases for every mixing sequence. Aspect ratios of the talc particles determined by TEM image analysis reasonably matched values computed from tensile modulus using composite theory. The thermal expansion behavior, or CTE values, was not significantly influenced by the mixing sequence. The impact strength of the PC/ABS/talc composites depended significantly on the mixing sequence; a premix with PC gave the poorest toughness. The molecular weight of the PC in PC/talc composites was found to be significantly decreased. It appears that the impact strength of the PC/ABS/talc composites is seriously compromised by the degradation of the PC caused by talc. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Processing‐dependent high impact polystyrene/styrene‐butadiene‐styrene tri‐block copolymer/carbon black antistatic composites

The electrical resistivity and morphology of high impact polystyrene (HIPS)/styrene‐butadiene‐styrene triblock copolymer (SBS)/carbon black (CB) blends were studied. Their antistatic sheets were prepared by both compression‐molding and extrusion calendaring process, with their surface morphology observed using scanning electron microscopy (SEM). The SEM images reveal better dispersion of CB achieved in extrusion‐calendering, resulting in low percolation threshold values in HIPS composites. Higher compression ratio and higher drawing speed (corresponding lower sheet thickness) are beneficial to get better CB dispersion, leading to decreased conductivity for the antistatic sheets. SEM images indicate that strong shear forces in extrusion tend to break the conductive network of CB, resulting in increased surface resistivity. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Water sorption into poly[(2‐hydroxyethyl methacrylate)‐co‐(1‐vinyl‐2‐pyrrolidone)] at 310 K

The original article to which this Erratum refers was published in November 2003 issue of Polymer International ( 52 : 1740–1748). Copyright © 2004 John Wiley & Sons, Ltd.     

Thermal evaluation of PHB/PP‐g‐MA blends and PHB/PP‐g‐MA/vermiculite bionanocomposites after biodegradation test

This study aimed to evaluate the thermal behavior of polyhydroxybutyrate (PHB)/polypropylene grafted with maleic anhydride (PP‐g‐MA) blends and PHB/PP‐g‐MA/vermiculite bionanocomposites submitted to the biodegradation test according to ASTM G 160‐03. The blends and bionanocomposites were prepared by melt intercalation method using a single screw extruder, and then, compression molded. The thermal analyzes were performed by thermogravimetry (TG) and differential scanning calorimetry. It was verified the decrease of onset degradation temperature and the melting temperature mainly after 86 days of exposure to the simulated soil. This behavior was more pronounced in bionanocomposites because of interactions between the maleic anhydride groups and the clay favoring biodegradation, making the systems more amorphous and propitious to the attack of microorganisms. POLYM. ENG. SCI., 56:555–560, 2016. © 2016 Society of Plastics Engineers     

Liquid–liquid phase separation in polysulfone/polyethersulfone/N‐methyl‐2‐ pyrrolidone/water quaternary system

To construct a phase diagram of the polysulfone (PSF)/polyethersulfone (PES)/N‐methyl‐2‐pyrrolidone (NMP)/water quaternary system, cloud point measurements were carried out by a titration method. The miscible region in the PSF/PES/NMP/water quaternary system was narrow compared to the PSF/NMP/water and PES/NMP/water ternary systems. The binary interaction parameters between PSF and PES were estimated by water sorption experiments. The calculated phase diagram based on the Flory–Huggins theory fit the experimental cloud points well. In addition to the usual polymer–liquid phase separation, polymer–polymer phase separation, which resulted in a PSF‐rich phase and a PES‐rich phase, was observed with the addition of a small amount of nonsolvent. The boundary separating these two modes of phase separation could be well described and predicted from the calculated phase diagrams with the estimated binary interaction parameters of the components. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 2113–2123, 1999     

Investigation on β‐polypropylene/PP‐g‐MAH/ surface‐treated calcium carbonate composites

β‐Polypropylene composites containing calcium carbonate treated by titanate coupling agent (T‐CaCO₃) and maleic anhydride grafted PP (PP‐g‐MAH) were prepared by melt compounding. The crystallization, morphology and mechanical properties of the composites were investigated by means of differential scanning calorimetry, wide‐angle X‐ray diffraction, polarized light microscopy, scanning electron microscopy and mechanical tests. It is found that both T‐CaCO₃ and NT‐C are able to induce the formation of β‐phase, and NT‐C greatly increases the β content and decreases the spherulitic size of PP. PP‐g‐MAH facilitates the formation of β‐form PP and improves the compatibility between T‐CaCO₃ and PP. Izod notched impact strength of β‐PP/T‐CaCO₃ composite is higher than that of PP/T‐CaCO₃ composite, indicating the synergistic toughening effect of T‐CaCO₃ and β‐PP. Incorporation of PP‐g‐MAH into β‐PP/T‐CaCO₃ composite further increases the content of β‐crystal PP and improves the impact strength and tensile strength when T‐CaCO₃ concentration is below 5 wt%. The nonisothermal crystallization kinetics of β‐PP composites is well described by Jeziorny's and Mo's methods. It is found that NT‐C and T‐CaCO₃ accelerate the crystallization rate of PP but the influence of PP‐g‐MAH on crystallization rate of β‐PP composite is marginal. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers