Radiopaque miscible systems composed of poly(methyl methacrylate) and transition and nontransition metal salts: Spectroscopic,thermal, and radiographic characterization

The preparation of miscible systems containing poly(methyl methacrylate) and cupric nitrate, manganese chloride, praseodymium chloride, and uranyl nitrate is described. The salt was dissolved in the monomer, which was subsequently polymerized. The heavy metal salts impart radiopacity to these plastics and this renders them useful for X-ray imaging in applications such as medical implants. The polymer–salt systems are characterized on the basis of their infrared spectra, thermal, and radiographic properties, and the formation of complexes between the cations and the carbonyl function of the polymer is discussed. The glass transition temperatures of the salt-containing polymers are higher than those of the salt-free polymers, the elevation being dependent on the nature and concentration of the metal salt. Miscible PMMA–uranyl nitrate systems are transparent, glassy plastics and approximately 11 wt % of uranyl nitrate hexahydrate imparts a radiopacity equivalent to that of aluminum.     

Investigation of nanostructure and properties of aromatic–aliphatic polyamide‐based nanocomposites with clay additives

Aromatic–aliphatic polyamide/clay nanocomposites were produced using solution intercalation technique. Surface modification of the clay was performed with ammonium salt of aromatic diamine and the polyamide chains were produced by condensation of 4‐aminophenyl sulfone with sebacoyl chloride (SCC) in dimethyl acetamide. Carbonyl chloride endcapped polymer chains were prepared by adding extra SCC near the end of polymerization reaction. The nanocomposites were investigated for organoclay dispersion, water absorption, mechanical, and thermal properties. Formation of delaminated and intercalated nanostructures was confirmed by X‐ray diffraction and TEM studies. Tensile strength and modulus improved for nanocomposites with optimum organoclay content (8 wt %). Thermal stability and glass transition temperatures of nanocomposites increased relative to pristine polyamide with augmenting organoclay content. The amount of water uptake for these materials decreased as compared with the neat polyamide. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Glucose hydrogenation on Co–B amorphous alloy catalysts and the promoting effect of metal additives

Two kinds of ultrafine Co–B amorphous alloy catalysts, denoted as P‐1 Co–B and P‐2W Co–B, were prepared by chemical reduction with borohydride in aqueous or 50% (v/v) ethanol/water solution, respectively. In comparison with the corresponding Co‐based crystalline catalysts and Ni‐based catalysts, these catalysts exhibited higher activity during the liquid phase glucose hydrogenation, possibly due to the unique amorphous characteristics and the lower d‐band electron density, which was favorable for hydrogen dissociative chemisorption. Addition of Cr‐, Mo‐ or W‐promoters could further increase the conversion of Co–B amorphous catalyst, which was mainly attributed to the dispersion effect of promoters and the adsorption and polarization of carbonyl groups by these promoters. The different effects of W‐ from Cr‐ and Mo‐promoters on the conversion were observed and are discussed. © 2001 Society of Chemical Industry     

Processing and properties of modified polyamide 66-organoclay nanocomposites

Binary polyamide 66 nanocomposites containing 2 wt % organoclay, polyamide 66 blend containing 5 wt % impact modifier, and ternary polyamide 66 nanocomposites containing 2 wt % organoclay and 5 wt % impact modifier were prepared by melt compounding method. The effects of E-GMA and the types of the organoclays on the interaction between the organoclay and the polymer, dispersion of the organoclay, morphology, mechanical, flow, and thermal properties of the nanocomposites were investigated. Partial exfoliation and improved mechanical properties are observed for Cloisite® 15A and Cloisite® 25A nanocomposites. On the other hand, the organoclay was intercalated or in the form of tactoids in Cloisite® 30B nanocomposites. Components of the nanocomposites containing Cloisite® 15A and Cloisite® 25A were compounded in different addition orders. Mixing sequence of the components affected both the dispersion of the organoclay and the mechanical properties drastically. SEM analyses revealed that homogeneous dispersion of the organoclay results in a decrease in the domain sizes and promotes the improvements in the toughness of the materials. Melt viscosity was also found to have a profound effect on the dispersion of the organoclay according to MFI and XRD results. Crystallinity of the nanocomposites did not change significantly. It is only the type of the constituents and their addition order what dramatically influence the nanocomposite properties. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

Effect of clay exfoliation and organic modification on morphological,dynamic mechanical,and thermal behavior of melt‐compounded polyamide‐6 nanocomposites

Polyamide‐6/clay nanocomposites were prepared employing melt bending or compounding technique followed by injection molding using different organically modified clays. X‐ray diffraction and transmission electron microscopy were used to determine the molecular dispersion of the modified clays within the matrix polymer. Mechanical tests revealed an increase in tensile and flexural properties of the matrix polymer with the increase in clay loading from 0 to 5%. C30B/polyamide‐6 nanocomposites exhibited optimum mechanical performance at 5% clay loading. Storage modulus of polyamide‐6 also increased in the nanocomposites, indicating an increase in the stiffness of the matrix polymer with the addition of nanoclays. Furthermore, water absorption studies confirmed comparatively lesser tendency of water uptake in these nanocomposites. HDT of the virgin matrix increased substantially with the addition of organically modified clays. DSC measurements revealed both γ and α transitions in the matrix polymer as well as in the nanocomposites. The crystallization temperature (T_c) exhibited an increase in case of C30B/polyamide‐6 nanocomposites. Thermal stability of virgin polyamide‐6 and the nanocomposites has been investigated employing thermogravimetric analysis. POLYM. COMPOS., 28:153–162, 2007. © 2007 Society of Plastics Engineers     

Blends of polyamide 6 with low‐density polyethylene compatibilized with ethylene–methacrylic acid based copolymer ionomers: Effect of neutralizing cations

Blends of polyamide 6 with low‐density polyethylene compatibilized with sodium‐, zinc‐, and lithium‐neutralized ethylene—methacrylic acid ionomers were investigated at 11, 33, and 55 wt % neutralization of the ionomers. Blends of polyamide 6 with low‐density polyethylene without a compatibilizer had poor properties characteristic of incompatible polymer–polymer blends. After the addition of a compatibilizer, tensile properties improved, the modulus drop associated with melting increased to higher temperatures, and the dispersed phase size decreased. The improvement of the mechanical properties and thermomechanical properties was less with the acid copolymer than with the ionomers. Overall, ionomers neutralized with sodium, zinc, or lithium showed little difference in their compatibilization efficiency. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

The use of polymers as sequestering agents for toxic metal ions

Polymer‐metal complexes were formed by nonsolvent precipitation technique for the metals Co, Pb, Ni, Cr, and Fe, and polystyrene (Pst), Poly(vinyl chloride) (PVC), and Nylon 66. By means of Fourier transform Infrared studies, it was established that chemical bonds actually do exist between the metal ions and the polymers (i.e., that the metal ions are not simply adsorbed on the surface of the polymers). It was observed also that the degrees of metal‐polymer interaction vary from polymer, from metal ion to metal ion, and depend on the metal ion concentration. These observations are explained in terms of the atomic radii and charges on the transition metal ions. The number and type of interaction sites/ligands on the substrates are also considered relevant. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2781–2786, 2002     

Mechanical and shape‐memory properties of polyamide/maleated polyethylene/linear low‐density polyethylene blend

Novel polymer blends of polyamide and linear low‐density polyethylene with maleated polyethylene as compatibilizers were prepared in a modular intermeshing corotating twin‐screw extruder. Polymer blends with different contents of polyamide in polyethylene matrix were obtained. The mechanical properties were studied in terms of the tensile strength and elongation‐to‐break. The shape‐memory properties of the blended materials were characterized using three‐point bending test in a temperature‐controlled chamber. The results show that the incorporation of maleated polyethylene has a strong effect on the tensile properties and the morphology of the blends. The shape‐memory effect of blended materials is affected by polyamide weight fraction, and 60 wt % polyethylene, 20 wt % polyamide, and 20% maleated polyethylene have an acceptable performance. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Crystallization behavior of PP/PP‐g‐MAH/GFR PA66 blends: Establishment of their continuous‐cooling‐transformation of relative crystallinity diagrams

Polypropylene/polypropylene‐grafted‐maleic anhydride/glass fiber reinforced polyamide 66 (PP/PP‐g‐MAH/GFR PA 66) blends‐composites with and without the addition of polypropylene‐grafted‐maleic anhydride (PP‐g‐MAH) were prepared in a twin screw extruder. The effect of the compatibilizer on the thermal properties and crystallization behavior was determined using differential scanning calorimetry analysis. The hold time was set to be equal to 5 min at 290°C. These conditions are necessary to eliminate the thermomechanical history in the molten state. The crystallization under nonisothermal conditions and the plot of Continuous‐Cooling‐Transformation of relative crystallinity diagrams of both PP and PA 66 components proves that PP is significantly affected by the presence of PP‐g‐MAH. From the results it is found that an abrupt change is observed at 2.5 wt % of PP‐g‐MAH as a compatibilizer and then levels off. In these blends, concurrent crystallization behavior was not observed for GFR PA66. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1620–1626, 2007     

Comparison of Electrocoagulation and Chemical Coagulation for Heavy Metal Removal

Copper (Cu), chromium (Cr), and nickel (Ni) removal from metal plating wastewater by electrocoagulation and chemical coagulation was investigated. Chemical coagulation was performed using either aluminum sulfate or ferric chloride, whereas electrocoagulation was done in an electrolytic cell using aluminum or iron electrodes. By chemical coagulation, Cu‐, Cr‐, and Ni‐removal of 99.9 % was achieved with aluminum sulfate and ferric chloride dosages of 500, 1000, and 2000 mg L^–1, respectively. Removal of metals by electrocoagulation was affected by the electrode material, wastewater pH, current density, number of electrodes, and electrocoagulation time. Electrocoagulation with iron electrodes at a current density of 10 mA cm^–2, electrocoagulation time of 20 min, and pH 3.0 resulted in 99.9 % Cu‐, 99.9 % Cr‐, and 98 % Ni‐removal.     

Dynamic–mechanical properties of modified poly(ethylene‐co‐vinyl acetate)

To study the relationship among relaxation peaks observed in dynamic mechanical experiments and the structure of poly(ethylene‐co‐vinyl acetate) (EVA), EVA copolymers with different substitution in the carbonyl group were synthesized. EVA was hydrolyzed to obtain poly (ethylene‐co‐vinyl alcohol) and was subsequently reacted with formic, hexanoic, and octanoic acids. The copolymers synthesized were characterized by infrared spectroscopy. Analysis of the DMA spectra of the copolymers showed that their relaxation behavior depends on the vinyl acetate concentration. The α‐ and β‐transitions were observed in EVA copolymers with 8 and 18 wt % of functional groups, and the relationship among relaxation process with the structure of polymer was investigated. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1371–1376, 2005     

Microstructure and mechanical behavior of polyamide 66‐precipitated calcium carbonate composites: Influence of the particle surface treatment

The effects of interfacial adhesion strength on the mechanical behavior of composites of polyamide 66 and precipitated calcium carbonate (CaCO₃) particles have been investigated. The 50 nm average diameter particles have been surface‐treated using two kinds of coupling agent having various affinities with respect to the matrix. The surface‐modified particles have been incorporated into the polyamide matrix via melt processing. Tensile and impact tests, associated with dynamical mechanical analysis, have been performed on injection‐molded samples. The structural characterization of the specimens has been carried out using differential scanning calorimetry and wide‐angle X‐ray scattering. It is observed that the matrix structure is roughly insensitive to the surface treatment, despite a weak nucleating effect of the filler particles. In contrast, the particle surface treatment strongly influences the particle dispersion in the polymer matrix. Although dispersion was not optimized, the elastic properties of the reinforced polyamide increase with the CaCO₃ content, below as well as above the glass transition temperature. Impact toughness decreases for CaCO₃ weight fraction greater than 5%. Scanning electron microscopy investigation reveals that the interfacial adhesion affects local deformation processes, such as debonding and fibrillation of the polymer matrix around the particles, during the macroscopic deformation of the composites. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 989–999, 2006     

Semitransparent poly(styrene‐r‐maleic anhydride)/alumina nanocomposites for optical applications

This article presents the development and characterization of transparent poly(styrene‐r‐maleic anhydride) (SMA)/alumina nanocomposites for potential use in optical applications. Chemically treated spherical alumina nanoparticles were dispersed in an SMA matrix polymer via the solution and melt‐compounding methods to produce 2 wt % nanocomposites. Field emission scanning electron microscopy was used to examine the nanoparticle dispersion. When the solution method was used, nanoparticle reagglomeration occurred, despite the fairly good polymer wetting. However, through the coating of the alumina nanoparticles with a thin layer (ca. 20 nm) of low‐molecular‐weight SMA, reagglomeration was absent in the melt‐compounded samples, and this resulted in excellent nanoparticle dispersion. The resultant nanocomposites were semitransparent to visible light at a 2‐mm thickness with improved UV‐barrier properties. Their impact strengths, tensile strengths, and strains at break were slightly reduced compared with those of their neat resin counterpart, whereas a small enhancement in their moduli was achieved. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Extension‐induced mechanical reinforcement in melt‐spun fibers of polyamide 66/multiwalled carbon nanotube composites

In this work, polyamide 66 (PA66) and its composites with multiwalled carbon nanotubes (MWNTs) were melt spun into fibers at different draw ratios. PA66 fibers at high draw ratio demonstrate a 40% increase in tensile strength, 66% increase in modulus and a considerable increase in toughness. It is demonstrated that this reinforcement can be mainly attributed to high‐draw‐ratio‐induced good dispersion and orientation of MWNTs, particularly the enhanced interfacial adhesion between MWNT and matrix thanks to interfacial crystallization. Our work provides a simple but efficient method to achieve good dispersion and strong interfacial interaction through melt spinning. Copyright © 2011 Society of Chemical Industry     

Arsenite retention properties of water‐soluble metal–polymers

The properties of water‐soluble metal–polymers to retain As(III) from aqueous solution are investigated. Poly(acrylic acid)s with different tin contents are prepared. Amounts of 3, 5, 10, and 20 wt % of tin are added to the polymer. The metal compositions are evaluated by thermogravimetry (TG‐DSC) and atomic absorption spectroscopy. Structural properties are analyzed by infrared and ¹H nuclear magnetic resonance spectroscopy, and X‐ray diffraction. Additionally, specific surface area was measured using CO₂ as adsorbate. Arsenic retention properties are studied using the liquid‐phase polymer‐based retention (LPR) technique. The polymers can bind arsenic species from an aqueous solution in the pH range 4–8. The studies show that the retention capacity is a function of tin content and polymer concentration. At pH 8, the following mol ratios poly(AA)‐Sn : As(III) are analyzed: 600 : 1, 400 : 1, 200 : 1, 100 : 1, and 20 : 1. The highest retention, 80%, is obtained with poly(AA)‐Sn at 10 and 20 wt % of tin at mole ratios 400 : 1, and at nearly to 20 : 1 or 40 : 1 Sn‐As(III). The highest retention is observed at pH 8 and 4. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Effects of the polymerization and pervaporation operating conditions on the dehydration performance of interfacially polymerized thin‐film composite membranes

The disadvantage of dense polyamide membranes when applied in the pervaporation separation process is their low permeation rates. To improve the pervaporation performance, polyamide thin‐film composite membranes were prepared via the interfacial polymerization reaction between ethylenediamine (EDA) and trimesoyl chloride (TMC) on the surface of modified polyacrylonitrile (mPAN) membranes. These composite membranes were applied in the pervaporation separation of alcohol aqueous solutions. On the basis of the best pervaporation performance, the desired polymerization conditions for preparing the polyamide thin‐film composite membranes (EDA–TMC/mPAN) were as follows: (1) the respective concentration and contact time of the EDA aqueous solution were 5 wt % and 30 min and (2) the respective concentration of and immersion time in the TMC organic solution were 1 wt % and 3 min. The polyamide thin‐film composite membranes (EDA–TMC/mPAN) exhibited membrane durability when applied in the pervaporation separation of a 90 wt % isopropyl alcohol aqueous solution at 70°C, which indicated that the polyamide thin film composite (TFC) membranes were suitable for the pervaporation separation process at a high operating temperature. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Removal of chromium,copper, and nickel ions using bidentate polymeric ligand derived from 4‐aminophenol and salicylaldehyde

The monomer 5‐(4‐acryloyloxyphenylazo)salicylaldehyde [5,4‐APASAL] was prepared and polymerized in dimethylformamide (DMF) at 70°C using benzoyl peroxide as free radical initiator. Poly5‐(4‐acryloyloxyphenylazo) salicylaldehyde [poly(5,4‐APASAL)] was characterized by infrared and nuclear magnetic resonance spectroscopic technique. The molecular weight of the polymer was determined by gel permeation chromatography method. Cu(II), Ni(II), Cr(III), and Cr(VI) complexes of poly(5,4‐APASAL) were prepared. Elemental analysis of polychelates suggests that the metal to ligand ratio is about 1 : 2. The polymer metal complexes were also characterized by XRD, magnetic moment, and thermal analysis. The effect of pH and electrolyte concentration in the metal uptake behavior of the polymer was also studied. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Compatibility of low‐density polyethylene/poly(ethylene‐co‐vinyl acetate) binary blends prepared by melt mixing

The compatibility of low‐density polyethylene and poly(ethylene‐co‐vinyl acetate) containing 18 wt % vinyl acetate units (EVA‐18) was studied. For this purpose, a series of different blends containing 25, 50, or 75 wt % EVA‐18 were prepared by melt mixing with a single‐screw extruder. For each composition, three different sets of blends were prepared, which corresponded to the three different temperatures used in the metering section and the die of the extruder (140, 160, and 180°C), at a screw rotation speed of 42 rpm. Blends that contained 25 wt % EVA‐18 were also prepared through mixing at 140, 160, or 180°C but at a screw speed of 69 rpm. A study of the blends by differential scanning calorimetry showed that all the prepared blends were heterogeneous, except that containing 75 wt % EVA‐18 and prepared at 180°C. However, because of the high interfacial adhesion, a fine dispersion of the minor component in the polymer matrix was observed for all the studied blends with scanning electron microscopy. The tensile strengths and elongations at break of the blends lay between the corresponding values of the two polymers. The absence of any minimum in the mechanical properties was strong evidence that the two polymers were compatible over the whole range of composition. The thermal shrinkage of the blends at various temperatures depended mainly on the temperature and EVA‐18 content. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 841–852, 2003     

Investigation of thermal degradation and flammability of polyamide‐6 and polyamide‐6 nanocomposites

In this paper, polyamide‐6 and polyamide‐6 nanocomposites were prepared by direct melt intercalation technique. The thermal degradation behavior of both polyamide‐6 and polyamide‐6 clay nanocomposites has been studied. The apparent activation energy of the nanocomposites is almost the same with that of pure polymer under nitrogen, but the apparent activation energy of the nanocomposites is greatly enhanced in air atmosphere. This increasing trend coincides with the thermal analysis and the cone calorimeter results, which may suggest that the polymer/clay nanocomposites have a higher thermal stability and lower flammability. The kinetic analysis also indicates that the pyrolytic degradation and the thermal oxidative degradation of PA6 and PA6/OMT nanocomposites are two kinds of different reaction models. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2297–2303, 2007     

Antibacterial Properties of Ester—Cross-Linked Cellulose–Containing Fabrics Post-Treated with Metal Salts

To improve the performance properties of cellulose-containing fabric, ester was cross-linked with polycarboxylic acid in the presence of specific catalysts. Its pendant carboxyl groups were exploited in binding some heavy metals (by reacting with some salts, such as zinc acetate, zinc chloride, zinc sulfate, cupric acetate, cupric chloride, cupric sulfate, and nickel sulfate) capable of imparting their antibacterial activity toward some gram-positive bacteria (viz., B. subtilis, B. mycoides, Sta. aureus) and a gram-negative bacteria (E. coli). Zinc salts impart to the fabric the highest antibacterial activity, followed by cupric acetate. Zinc chloride proved to be the metal salt that yielded the maximum antibacterial activity.