Effects of the structure of polymer and nanosilica additive on the sorption and electric properties of various alginate fibers

Effects of the structure of polymer and nanosilica additive on the sorption and electric properties of various alginate fibers has been investigated. It has been found that regardless of the differences in the chemical structure and the presence of nanosilica, the examined types of alginate fibers show similar values of moisture absorption at relative humidity up to 85%. An exception is the fiber from sodium alginate. It has been found that the electric conductivity and the accompanying polarization processes of various types of alginate fibers depend on the chemical structure of the fiber‐forming polymer. It has been found that the amount of moisture absorbed by the fiber‐forming polymer of alginate fibers exerts a strong influence on their electric properties. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 686–694, 2006     

Acidic hydrolysis of a poly(vinyl acetate) matrix by the catalytic effect of Ag nanoparticles and the micellization of Ag‐metal‐containing polymer

In this study, we conveniently obtained Ag(0)–polymer nanocomposites by reacting AgNO₃ with commercial poly(vinyl acetate) (PVAc) in the absence of a special reducing agent. The formation of Ag(0) metal was detected after formic acid (HCOOH) was added to a PVAc–AgNO₃ complex system, and some of the acetate groups of the PVAc backbone were hydrolyzed to form hydroxyl groups (OH) under the catalytic effect of the reduced Ag(O) metal. Here, the structure of the partially hydrolyzed PVAc backbone was represented as PVOH‐PVAc. X‐ray diffraction spectra showed that the Ag(0) metal generated in this method was in the form of Ag crystals. The structure of the Ag(0)–polymer was analyzed by ¹H‐NMR and ¹³C‐NMR spectroscopy. The micellization of the Ag(0)–polymer was also investigated by the addition of an inducing solvent to the formic acid solution of Ag(0)–polymer. The image showed that the morphology of the Ag micelles in the H₂O‐induced solvent was a Ag corona with a Ag shell, and that in the p‐xylene induced solvent showed a Ag cluster core structure. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1457–1464, 2006     

Rupture of nanoparticle agglomerates and formulation of Al2O3‐epoxy nanocomposites using ultrasonic cavitation approach: Effects on the structural and mechanical properties

Currently, intense research is underway to develop polymer nanocomposites because of their numerous potential applications. However, the uniform dispersion of inorganic nanoparticles in polymer nanocomposites without an additional chemical phase has proved to be a difficult challenge. In this paper, we present our results that ultrasonic cavitation could be an effective tool to disrupt agglomerates, thus forming well‐dispersed inorganic phase polymer nanocomposites. This is especially true if polymer degradation could be minimized during ultrasonic processing. Our results suggest that better dispersion of nanoparticles achieved via ultrasonic cavitation not only improved the elastic modulus of the polymer nanocomposites but also enhanced the stress at 5% strain values. POLYM. ENG. SCI. 46:426–430, 2006. © 2006 Society of Plastics Engineers.     

Synthesis of polyethylene using ultrasonic energy with a metallocene catalyst

Ethylene polymer was synthesized by the treatment of a metallocene catalyst Zr(CP)₂Cl₂ solution with ultrasonic energy. Ultrasonic energy irradiation was used to change the polymer structure of the formed polymer. Different ultrasonic energy irradiation times were applied to the metallocene catalyst solution. The ultrasonic energy had an effect on the average molecular weight, molecular weight distribution, and polymer productivity. A lower average molecular weight and a narrower molecular weight distribution were produced with a longer ultrasonic irradiation time. The polymer productivity was almost constant when the metallocene catalyst was treated with ultrasonic energy. Finer polyethylene particles were produced with longer ultrasonic irradiation times. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 756–759, 2006     

Application of Fourier transform infrared spectroscopy in the study of interactions between PVC and plasticizers: PVC/plasticizer compatibility versus chemical structure of plasticizer

Fourier transform infrared spectroscopy is applied in the study of interactions between PVC resin and plasticizers in flexible PVC systems. The comparison of the theoretical infrared spectra coming from the addition of the respective component infrared spectra with those of PVC/plasticizer experimental systems gives information about polymer/plasticizer interaction degree. In addition, solvation capacity of the plasticizer varies as a function of its chemical structure, giving rise to compatibility differences between the system components. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1731–1737, 2006     

Changes of fluorescence color in novel poly(azomethine) by the acidity variation

A novel polymer, poly(4,4′‐oxydiphenylenemethylidynenitrilo‐2,5‐dihexyloxy‐1,4‐phenylenenitrilomethyli‐ dyne) (POPNM), with a azomethine structure, containing long alkoxy side chains, was synthesized by the polycondensation of 2,5‐bis(hexyloxy)terephthalaldehyde with 4,4′‐oxydianiline. It displayed acid‐sensory properties as colorimetric and fluorescent transducers to the strong acid analytes because of the protonation of an imine group in the compound. To examine the sensitivity to the acid, the effect of absorption and fluorescence of the polymer was investigated by simply adding trifluoroacetic acid into a chloroform solution of the polymer, and as a result, the multiple colors of fluorescence were sharply changed. Increasing the amount of the acid, the maximum absorption bands of fluorescence spectra were bathochromically shifted from 470 to 570 nm and, then, treating the pyridine as a base, they were recovered. A polymer film containing both the polymer and a photoacid generator (PAG) was prepared by semi‐interpenetrating network polymerization method. When the polymer film was exposed to UV in the presence of PAG through a photomask, well‐resolved fluorescent image patterns were readily obtained. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1228–1233, 2006     

Readily decomposed thermosetting resins for recovering and reusing resin‐embedded materials

To help recover the intrinsically valuable, reusable metal parts at the end of a product's life‐cycle, we have used thermosetting (epoxy) resin that contains a small amount of thermoplastic polymer, polyethersulfone, which can be readily chemically decomposed. In a morphologically homogeneous modified thermosetting resin, the resin portion does not readily decompose when treated with an organic solvent, and chemical resistance equals the unmodified epoxy resin. A resin portion with thermoplastic polymer having continuous‐phase morphology was finely broken down by treatment with an organic solvent, and the embedded metal parts were separated and recovered. Readily decomposed thermosetting resin can thus be obtained by controlling the morphology of the thermoplastic polymer in the thermosetting resin to form a continuous phase. We also obtained a material having continuous variation in the phase morphology of a cured resin, from that with homogeneous morphology to that with continuous‐phase morphology of the thermoplastic polymer: phase structure inclination material. We were thus able to control the decomposition rate by chemical treatment in one resin. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1463–1470, 2006     

The structure of high-strength ultrahigh-molecular-weight polyethylene fibres fabricated by the gel-spinning method

In orientation drawing of UHMPE (ultrahigh-molecular-weight polyethylene) fibres, conformational rearrangements take place that enrich the conformation set of the polymer with T-isomers and impoverish it in G-isomers. The basic increase in the orientation of T-isomers is observed in the initial stages of drawing. In orientation drawing of UHMPE gel fibre, no significant increase was found in the concentration of molecular breaks, a necessary condition for effective strengthening of the fibre. Two types of crystallites (crystallites infolded and straightened chains) and a mesophase were found in samples of multifilament UHMPE fibres. There is a smooth transition from the structure of the folded-chain crystallite (FCC) type to a structure of the straightened-chain crystallite (SCC) type with an increase in the draw ratio due to formation of a rigid amorphous phase of straightened segments of the polymer chains. __________ Translated from Khimicheskie Volokna, No. 3, pp. 18–23, May–June, 2006.     

A structural model of an accessibility of polycarbonate melt to thermooxidative degradation processes

It is shown that the “accessibility” of a polymer for oxidation is the only structural factor and quantitative estimate within the framework of the fractional derivation. The oxidation rate of the “accessible” part of a macromolecular coil is independent on its structure, which allows to assume its dependence only on the chemical constitution of polymer. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 3765–3768, 2006     

Curing behavior,mechanical properties,intermolecular interaction,and morphology of silicone/polypyrrole/polymer electrolyte composites

The curing behavior, mechanical properties, intermolecular interaction, and morphology of silicone, polypyrrole, and polymer electrolyte composites were studied. A rigid‐body pendulum rheometer was used to determine the curing behavior of silicone/PEL blends. The polymer structure was evaluated using FTIR and Differential Scanning Calorimetery. The mechanical properties, including stress, strain, and hardness, were measured using a material testing system. The morphology of the composites was measured using scanning electron micrographs. The intermolecular interaction of the composites was measurement using dynamic mechanical analysis. The results show that the curing reaction rate is fast upon addition of 10 wt % of polymer electrolyte for silicone. The linear molecular structure of the polymer electrolyte was wound around the silicone polymer network structure forming a semi‐interpenetrating network. The intermolecular interaction was influenced by the composites, and the Ppy film effect on the surface of SP10 blends is more uniform than that of silicone. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2754–2764, 2006     

Mechanistic study of boron trifluoride catalyzed ε‐caprolactone polymerization in the presence of glycerol

Boron trifluoride catalyzed ε‐caprolactone polymerization in the presence of glycerol can produce poly(ε‐caprolactone) with a high weight‐average molecular weight and a broad molecular weight distribution. This article reports an investigation of the polymerization mechanism to determine the formation of these molecular weight features through a study of the polymerization kinetics and the molecular structure with NMR. The polymerization proceeds via an activated monomer mechanism, resulting in polymer molecules with hydroxyl chain ends. The broad molecular weight distribution can be attributed to the etherification reactions between hydroxyl chain ends. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3900–3906, 2006     

Porous polyphenylene sulfide membrane with high durability against solvents by the thermally induced phase‐separation method

Porous polyphenylene sulfide membranes were prepared as new solvent‐resistant membranes by the thermally induced phase‐separation (TIPS) method. Porous structures were either formed by solid–liquid phase separation (polymer crystallization) or liquid–liquid phase separation. The effects of solvents, cooling rates, and polymer concentrations on the porous structures were investigated. Various characteristics of pore structure can be obtained with suitable diluents and cooling rates using the TIPS method. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2959–2966, 2006     

Study on the rheological behavior of the hydrophobically modified hydroxyethyl cellulose with 1,2‐epoxyhexadecane*

Through the macromolecule reaction method, the hydrophobically modified hydroxyethyl cellulose (EP16–HAHEC) was synthesized using 1, 2‐epoxyhexadecane as the hydrophobic monomer. The solution properties of EP16–HAHEC were comprehensively investigated, which showed that the polymer with enhanced; viscosification property, thermal stability, shear resistance, and salt resistance was obtained. Amphiphilic structure of EP16–HAHEC molecules contributed to the surface activity of the polymer. By forming complex solution with surfactants or carboxylmethyl cellulose (CMC), the viscosification property of EP16–HAHEC could be enhanced through the interactions of hydrophobic groups and hydrogen bonds. The viscosity‐enhancing mechanism of HAHEC was studied by the environment scan electronic microscope (ESEM) and the fluorescence spectrum measurements, which demonstrated that the formation of the supramolecular aggregation networks was coincident with the increase of the apparent viscosity of HAHEC. With the gradual formation of the complete polymer molecule networks, the apparent viscosity rised dramatically, and the associating aggregations of the polymer molecules appeared far before the great change of the macroproperty of the polymer. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2953–2959, 2006     

Rheological properties of hydrophobically modified polyelectrolyte systems: Concentration effects

The behavior of hydrophobically modified alkali‐soluble associative polymer (HASE) at various polymer concentrations was investigated. The results showed that the formation of network structure, which enhances the rheological behavior, depends on two critical polymer concentrations, namely the critical cluster overlapping concentration (C*) and the established network concentration (C**). C* is defined as the critical concentration for the transformation of individual cluster to a transient network structure. C** represents the critical concentration in the semidilute regime where the formation of transient network is completely established. Experimental results demonstrated that the polymer solutions transformed from a predominantly viscous behavior below C* to one with dominant elastic properties above C**. Because of the formation of larger aggregation number above C**, the relaxation times of the polymer systems shift to longer times. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5166–5173, 2006     

Factors defining the selectivity polymer membranes: A fractal model

It is shown that the selectivity of the polymer nonporous membranes by the diffusivity depends on the polymer structure by rather complex way. The most important characteristic in this case is the dimension D_t controlling the gas transport processes and the molecular mobility degree influences only at large enough values of diameter of the selected gas molecules, the difference of these diameters and the dimension D_t. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 331–333, 2006     

New procedure to calculate the Hansen solubility parameters of polymers

The simplest experimental method to determine the Hansen solubility parameters (HSPs) for a polymer is to evaluate whether or not it dissolves in selected solvents. Those solvents dissolving the polymer will have HSPs closer to those of the polymer than those that do not. A computer program or graphical method can then be used to find the HSP for the polymer. In this work, an improved method for calculating the HSP of polymers, based on the Nelder–Mead optimization algorithm, is presented. The results of this program fit the data very well. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 31–36, 2007     

高分子材料微观形态结构的扫描电镜研究

利用扫描电镜对聚乙烯(PE)、丙烯腈-丁二烯-苯乙烯共聚物(ABS)等高分子材料填料的分散性及表面与断裂界面进行了研究。结果表明,扫描电镜能够详细观察研究高分子材料的表面结构、微观相分离等,便于表征高分子材料微观结构形态,是分析高分子材料微观结构形态的有效手段。     

Long‐chain branching of polypropylene by electron‐beam irradiation in the molten state

The electron‐beam irradiation of polymers generates modification effects in the macromolecular structure and material properties. Therefore, irradiation processing is mostly realized in the polymer solid state. In this way, the modification of linear polypropylene may result in long‐chain branching of polypropylene macromolecules. The objective of this article is to investigate the effect of a polymer in the molten state during electron‐beam irradiation on the macromolecular structure and material properties of polypropylene. For this procedure, a special irradiation vessel (BG3) has been developed in which a rapid transfer of polymer films from the solid state to the molten state and a defined temperature during electron‐beam irradiation are realizable. The irradiated samples have been analyzed by high‐temperature size exclusion chromatography coupled with a multi‐angle laser light scattering detector and differential scanning calorimetry (DSC) measurements. With an increasing irradiation dose, a high reduction of the molar mass and an increasing amount of long‐chain branching are found. Compared with irradiation in the solid state, the modification in the molten state leads to a higher degree of branching. The rheological experiments in elongation flow clearly exhibit the existence of long‐chain branching. Furthermore, DSC measurements show that the glass‐transition temperature and peak temperatures of melting and crystallization decrease. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 260–265, 2006     

Polymer electronic materials: a review of charge transport

This article presents an overview of the charge transport phenomenon in semiconducting polymer materials. In these disordered systems both intrinsic and extrinsic parameters play significant roles. In general, π‐electron delocalization, interchain interaction, band gap, carrier density, extent of disorder, morphology and processing of materials determine the electrical and optical properties. The chemical structure, especially the role of side groups, is quite important in both physical and processing properties. The nature of charge carriers and their role in charge transport depend on the structure and morphology of the system. Hence in several semiconducting polymer devices, the correlations among structure, morphology and transport are rather strong. The dependence of carrier mobility on temperature and electric field needs to be understood in the framework of competing models based on carrier hopping, trapping/detrapping and tunneling. Exactly what determines the dispersive/nondispersive, polaronic and correlative transport regimes is yet to be quantified. An understanding of the carrier mobility in semiconducting polymers is necessary to optimize the performance of polymeric electronic devices. Copyright © 2006 Society of Chemical Industry     

Melting aspects of filled compounds in a modular co‐rotating twin screw extruder

In the polymer industry, precompounded materials are widely used. Carefully designed melting experiments were carried out to investigate melting mechanisms in master batched polymer compounds, using an intermeshing co‐rotating twin screw extruder. Calcium carbonate or aluminum powder was master batched with linear low‐density polyethylene (LLDPE). The calcium carbonates, which were used in the compounds, have differences in weight fraction and particle size. The compounds containing filler have higher thermal conductivities and viscosities than neat polyethylene. We observed melting initiation and propagation mechanisms of LLDPE compounds by removal and characterization of polymer compound carcasses in the melting region. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1990–2012, 2006