Conductivity and structure of a polyamide/silver iodide nanocomposite

In this study, the structure and properties of an organic–inorganic composite material prepared from nylon 6 doped with fine particles of silver iodide (AgI) were examined. The preparation of the composite involved the complexation of nylon 6 with polyiodide ions such as I and I by immersion in an iodine/potassium iodide (I₂–KI) aqueous solution followed by reaction in a silver nitrate (AgNO₃) aqueous solution; this resulted in the in situ formation of β-AgI fine particles within the nylon 6 matrix. The AgI content formed in the composite was dependent on the immersion temperatures of the I₂–KI and AgNO₃ solutions. Lower solution temperatures resulted in larger amounts of AgI in the composite. This method readily provided a composite with a high content of AgI in nylon 6 and a conductivity of approximately 10⁻⁵ Ω⁻¹ cm⁻¹. In a uniaxially oriented nylon 6 matrix, AgI particles precipitated with anisotropic shape, which was caused by the orientation of the precursor polyiodide ions. The structure of the oriented composite provided the anisotropic conductivity. Additionally, the composite exhibited high antibacterial properties. The procedure used in this study is considered a unique method for the preparation of organic–inorganic composites. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Preparation and properties of polyamide 6/polypropylene–vermiculite nanocomposite/polyamide 6 alloys

Polypropylene–vermiculite nanocomposites can be achieved by simple melt mixing of maleic anhydride‐modified vermiculite with polypropylene. Maleic anhydride acts either as a compatibilizer for the polymeric matrix or as a swelling agent for the silicate. Compatibilized blends are injection molded directly from polyamide 6 and polypropylene–vermiculite nanocomposites. Scanning electron microscopy observation reveals that a two‐phase structure consisting of polypropylene–vermiculite nanocomposite and polyamide 6 is formed in the blends. The absence of vermiculite reflections in the X‐ray powder diffraction patterns indicates that the polypropylene–vermiculite phase exhibits nanocomposite characteristics. Tensile test shows that the tensile modulus of the polymer alloy tends to increase with increasing polypropylene–vermiculite nanocomposite content. The tensile strength of composite containing 8 wt % vermiculite is higher than that of pure polyamide 6. Finally, the thermal properties of the nanocomposites are determined by dynamic mechanical analysis, differential scanning calorimetry, and thermogravimetric measurements. The effects of maleic anhydride addition on the formation of polypropylene–vermiculite nanocomposite reinforcement and on the mechanical properties of composites are discussed. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2330–2337, 2002     

Trends in graphene reinforced polyamide nanocomposite for functional application: a review

This review outlines significant aspects and vital progression from polyamide – to – polyamide/graphene nanocomposite – to – technical application. Polyamide forms an important class of engineering thermoplastic polymers with exceptional mechanical, abrasion, wear, barrier, and crystallinity properties. Graphene is a unique nanocarbon having exclusive electrical, optical, mechanical, thermal, and chemical performance. Consequently, polyamide/graphene nanocomposite has revealed multifunctional properties and high performance owing to the synergistic effect of polymer and graphene. Here, interfacial interaction, dispersion in matrix, and processing technique used affect the final nanocomposite performance. A range of technological fields have been profited using polyamide/graphene nanocomposites including non-flammable materials, membranes, coatings, textile, and packaging industries.     

Mechanical and morphological properties of a ternary polyamide 6 nanocomposite with optimized stiffness/toughness performance

While developing new polymers, a high level of stiff and simultaneously tough material behavior is an important goal. This study shows a new approach to optimize the stiffness/toughness behavior of polyamide 6 (PA 6) by incorporating both stiff and elastomeric nanofillers during melt compounding. For stiffness enhancement of PA 6, an organic‐modified layered silicate (organoclay) was used, whereas to compensate for the toughness properties, a nanostructured PA 6/polyether block copolymer (PA 6‐copo) was applied. In the first step, binary nanocomposites have been investigated whereby correlations between morphological and mechanical properties have been derived. Subsequently, these results have been used to adapt the processing conditions for the ternary nanocomposites. Despite a considerable interaction of both nanofillers the stiffness/toughness balance of the PA 6 nanocomposite has been optimized significantly. At a filler content of only 8 mass% organoclay and 8.3 mass% PA 6‐copo, Young's modulus and tensile strength of PA 6 could be increased by 55% and 18%, respectively. In addition, the notched impact strength of PA 6 was enhanced substantially by 58%. POLYM. ENG. SCI., 54:247–254, 2014. © 2013 Society of Plastics Engineers     

Morphology, structure and properties of a poly(1-butene)/montmorillonite nanocomposite

A specifically formulated nanocomposite based on isotactic poly(1-butene) (PB) and montmorillonite was studied, by wide angle X-ray diffraction (WAXD), small angle X-ray scattering (SAXS), transmission electron microscopy (TEM) and polarized light optical microscopy, investigating the polymorphism of the polymer, and examining the interaction between PB and the silicate. Montmorillonite was found to disrupt the ordered morphology of the polymer, determining a dramatic increase in the rate of the II→I phase transition. Interaction between polymer and clay was studied by TEM and SAXS also under a quantitative point of view. A significant enhancement of physical-mechanical properties was observed, even though exfoliation did not occur, but just a slight intercalation and a reduction in the size of tactoids.     

Effect of clay treatment on structure and mechanical behavior of elastomer-containing polyamide 6 nanocomposite

The effect of clay organophilization on mechanical behavior and structure of PA6/EPR blends was studied. It has been shown that the modification of clay affected simultaneously the degree of PA6 matrix reinforcement, size and structure of dispersed EPR. The localization of clay with less polar treatment in the interfacial area brought an important new effect consisting intensification of toughening effect of dispersed elastomer by formation of “core-shell” particles. Basic aspects governing formation of this advantageous structure are reported.The best balanced mechanical behavior was achieved when combining two differently modified clays, whereas the clay with less polar treatment is preblended with EPR. In this way, a high degree of matrix reinforcement (exfoliation of clay with more polar treatment) was combined with favorable size and structure of dispersed EPR phase. Additionally, at lower clay content, synergy between clay and elastomer phase, monitoring itself by enhancement of toughness, was found.     

锦/涤复合丝POY油剂的研制和性能研究

根据锦/涤复合丝POY纺丝工艺对油剂的要求,确定以甜菜碱两性型表面活性剂和脂肪醇聚醚磷酸酯盐阴离子表面活性剂为抗静电剂,以聚醚和封端聚醚作为平滑剂,制备了锦/涤复合丝POY油剂(1#),并与进口油剂德国SS公司K-105油剂(2#)和日本竹本油脂公司的F-2169油剂(3#)及国产油剂YDG-2000A(4#)在平滑性、耐热性、抗静电性等性能方面进行了比较。结果表明:所研制的1#油剂的平滑性、耐热性、抗静电性等指标达到或超过了2#,3#进口油剂及4#国产油剂;工业化应用结果表明,1#油剂可纺性好,所得锦/涤复合丝POY染色M率达到93%以上,一等品率达到95%以上。     

Polyurethane/clay nanocomposites foams: processing, structure and properties

Polyurethane (PU)/montmorillonite (MMT) nanocomposites were synthesized with organically modified layered silicates (organoclays) by in situ polymerization and foams were prepared by a batch process. Clay dispersion of polyurethane nanocomposites was investigated by X-ray diffraction and transmission electron microscopy. The morphology and properties of PU nanocomposites and foams greatly depend on the functional groups of the organic modifiers, synthesis procedure, and molecular weight of polyols because of the chemical reactions and physical interactions involved. Silicate layers of organoclay can be exfoliated in the PU matrix by adding hydroxyl and organotin functional groups on the clay surface. The presence of clay results in an increase in cell density and a reduction of cell size compared to pure PU foam. In the polyurethane with high molecular weight polyol, a 6 °C increase in T_g, 650% increase in reduced compressive strength, and 780% increase in reduced modulus were observed with the addition of 5% organically treated clays. Opposite effects were observed in PU nanocomposite foams with highly crosslinked structure. The interference of the H-bond in the presence of clay is probably the reason.     

Preparation,structure, and properties of a novel rectorite/styrene–butadiene copolymer nanocomposite

Rectorite/styrene–butadiene copolymer (SBR) nanocomposite was prepared by cocoagulating SBR latex and rectorite/water suspension. Transmission electron microscopy showed that the layers of rectorite were well dispersed in the SBR matrix and the aspect ratio (width/thickness) of it was higher than that of montmorillonite (MMT). X‐ray diffraction indicated that the nanocomposite produced by this method was of neither intercalated type nor exfoliated type. The gas barrier properties and mechanical properties of the novel nanocomposites were excellent. The nanocomposites are expected to be candidates for tire tube or inner materials. Rectorite appears to be a promising filler for the nanocomposite. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 324–328, 2005     

Pectinlyase immobilization on polyamides for application in the food processing industry

The study concerns the immobilization of a pectinlyase (PL, EC 4.2.2.3) purified by means of a commercial enzyme for its possible applications in fruit juice and beverage processing. Results previously obtained were improved by employing polyamides, i.e. nylon 6 and nylon 11, activated by easy to perform and inexpensive methods such as direct activation with glutaraldehyde and alkylation with dimethylsulphate followed by treatment with amines and glutaraldehyde. The nylon 6 activated with glutaraldehyde gave an activity of the immobilized PL of about 200 U g^?1 (at optimum pH) and a half-life of about 190 h (at pH 3·3 and 25°C).     

Effects of processing parameters on material properties of mechanically processed polyamide

A semicrystalline polyamide polymer was processed using a new technique known as mechanical alloying. The material processed by this technique was first introduced into a high-energy ball mill and ground over long periods of time, resulting in the production of extremely fine powders. These powders were subsequently consolidated well below the materials' melting-point temperature. The effect of processing parameters including mechanical milling time, consolidation temperature, and the length of consolidation time were studied fairly extensively. The investigation shows that polyamide powders are continually refined with increasing mechanical milling time and the resulting materials have improved mechanical properties. The influence of both consolidation temperature and the length of consolidation time on material properties indicate that materials with higher density, crystallinity, hardness, strength, and ductility are produced when consolidated using higher temperatures and longer times. © 1995 John Wiley & Sons, Inc.     

Morphology,structure, and properties of metal oxide/polymer nanocomposite electrospun mats

Adding nanoparticles into polymer solutions before electrospinning creates unique hierarchical morphologies dispersed throughout small diameter nanoparticle‐polymeric fibers. Effects of polymer composition, nanoparticle (NP) type, loading, and electrospinning voltage conditions were studied. As examples, indium, iron, and titanium oxide engineered nanoparticles (NPs) were dispersed into polyvinylpyrrolidone or polystyrene and electrospun. NP loadings below 5 wt % did not affect critical voltage required for Taylor cone formation, whereas higher NP loadings require higher critical voltages. Polymeric fiber thickness and macroscopic morphology is not impacted by up to 5 wt % NP loadings, and NP dispersion throughout the fibers were similar to their dispersion in initial polymer suspension. NP loadings above 5 wt % increased viscosity, which decrease subsequent fiber diameter. Experiments in water containing inorganic and organic pollutants in water demonstrate that the polymer is largely nonporous. This work enables design of multifunctional nanomaterial‐polymer composite fibers for wide‐ranging applications such as water and air treatment. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43811.     

Pd/SBA-15 nanocomposite: Synthesis, structure and catalytic properties in Heck reactions

Pd nanoparticles supported in mesoporous silica SBA-15 (or Pd/SBA-15 nanocomposites) were prepared by ion-exchange with cationic Pd precursor in an alkaline solution on an uncalcined silica. The high Pd loading in these nanocomposites can be achieved up to 5.21 wt.% by adjusting the pH value of the solution. The surface area and the pore volume decrease with increasing Pd loading. The Pd nanoparticles equal to or smaller than 6 nm in size in the nanocomposites are distributed in the channels of the mesoporous SBA-15. The Pd/SBA-15 nanocomposites exhibit excellent catalytic activities and high reuse ability in air for the Heck carbon-carbon coupling reactions.     

Preparation of polyamide monofilaments for microsurgery,and their properties

Conclusions Dyed polyamide monofilaments have been prepared, designed for use as satures in microsurgery.The most stable physicomechanical characteristics of polyamide monofilaments for the needs of microsurgery (uniformity in diameter, intensity and stability of color after the action of biological media) can be obtained only on special preparations of monofilaments which have been dyed in bulk.Translated from Khimicheskie Volokna, No. 6, pp. 45–46, November–December, 1984.     

Morphology, structure and properties of conductive PS/CNT nanocomposite electrospun mat

The morphologies and properties of Polystyrene (PS)/Carbon Nanotube (CNT) conductive electrospun mat were studied in this paper. Nanocomposite fibers were obtained through electrospinning of PS/Di-Methyl Formamide (DMF) solution containing different concentrations and types of CNTs. The dispersion condition of CNTs was correlated to morphologies and properties of nanocomposite fibers. A copolymer as an interfacial agent (SBS, Styrene-butadiene-styrene type) was used to modify the dispersion of CNTs in PS solution before electrospinning. The results showed that the presence of the copolymer significantly enhances CNT dispersion. The fiber diameters varied between 200 nm and 800 nm depending on CNT type, polymer concentration and copolymer. The final morphological study of the fibers showed that CNT addition caused a decrease in beads formation along fiber axis before percolation threshold. However, addition of CNTs above percolation increased the beads formation, depending on the dispersion condition. The presence of SBS modified the dispersion, reduced the fiber diameter and the number of bead structures. Electrical conductivity measurements on nanocomposite mats of 15-300 μm in thickness showed an electrical percolation threshold around 4 wt% MWCNT; while the samples containing SBS showed higher values of conductivities below percolation compared to the samples with no compatibilizer. Enhancement in mechanical properties was observed by the addition of CNTs at concentrations below percolation.     

层状硅酸盐/橡胶纳米复合材料的结构、性能、工业化及其在轮胎工业中的应用

介绍粘土晶层水分散体/橡胶乳液共混共凝制备纳米复合材料的原理、复合材料的结构和性能以及在轮胎工业中的应用.层状硅酸盐/橡胶纳米复合材料具有优异的静态物理性能、气体阻隔性能、耐疲劳性能以及一定的阻燃性能和抗烧蚀性能,应用于轮胎内胎、工程机械轮胎胎面和输送带覆盖胶等可提高产品性能.     

Pectinlyase immobilization on epoxy supports for application in the food processing industry

The immobilization of a pectinlyase (PL, EC 4.2.2.3) contained in a commercial enzymic preparation was studied in view of its use for fruit pulp and juice processing. Two epoxy supports were tested for immobilization. These included Eupergit C (Rohm), a synthetic polymer, and γ-alumina functionalized with γ-glycidoxypropyltrimethoxysilane. In both biocatalysts, the catalytic response was not found to be high. The highest response in terms of immobilization yield and immobilized PL activity, however, was reported for Eupergit C (approx. 115 unit g^?1 at optimum pH).     

Fabrication,structure, and properties of chitin whisker‐reinforced alginate nanocomposite fibers

Calcium alginate yarn (30 fibers) and calcium alginate nanocomposite yarn (30 fibers) containing 0.05–2.00% w/w chitin whiskers were both prepared by wet spinning process. The whiskers were prepared by acid hydrolysis of chitin from shrimp shells. The average length and width of the whiskers were 343 and 46 nm, with the aspect ratio being ～ 7.5. Incorporation of a low amount of the whiskers in the nanocomposite fibers improved both the mechanical and the thermal properties of the fibers significantly, possibly a result of the specific interactions, i.e., hydrogen bonding and electrostatic interactions, between the alginate molecules and the homogeneously dispersed chitin whiskers. Biodegradation of the calcium alginate fibers and the nanocomposite fibers was tested in Tris‐HCl buffer solution and the same buffer solution that contained lysozyme. The addition of the chitin whiskers in the nanocomposites fibers accelerated the biodegradation process of the fibers in the presence of lysozyme, whereas the presence of Ca²⁺ ions in the Tris‐HCl buffer solution helped to improve the tenacity of both the alginate and the nanocomposite fibers. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Morphological and mechanical characterization of a PMMA/CdS nanocomposite

Thick film of poly(methyl methacrylate) (PMMA)/CdS nanocomposite have been synthesized by the solution casting process. The nanostructure of the CdS particles has been ascertained through the small angle X-ray scattering (SAXS) technique. The surface morphological characterization of the PMMA/CdS nanocomposite has been done through scanning electron microscopy (SEM) analysis. The variation of mechanical loss factor (Tanδ) with temperature and tensile properties of prepared samples have been studied using Dynamic Mechanical Analyzer (DMA). This study reveals that the glass transition temperature (T_g), Young’s modulus, and fracture energy of the PMMA/CdS nanocomposite are greatly influenced by the existence of interfacial energetic interaction between dispersed CdS nanoparticles and the matrix of PMMA.