The effect of variation in polymer properties on the rate of burning

The sensitivity of the burning rate to variations in physical and chemical properties of synthetic polymers has been examined in order to understand the relative importance of the knowledge of these properties. The sensitivity analysis was performed using a numerical pyrolysis model called ThermaKin, which was employed to compute the rate of burning (expressed in terms of mass loss) of a one‐dimensional material object exposed to steady radiative heat. The results of the calculations indicate that the knowledge of decomposition reaction parameters (including the Arrhenius pre‐exponential factor, activation energy, heat, and char yield) is of key importance for prediction of the peak and average burning rates. Copyright © 2009 John Wiley & Sons, Ltd.     

Surface‐enhanced infrared absorption (SEIRA) and its use in analysis of plasma‐modified surface

A thin film (<10 nm) of fine metal clusters (silver or gold) with an island form was deposited on a CaF₂ salt plate by slow vacuum thermal evaporation. Molecular layers of stearic acid, p‐nitrobenzoic acid, and m‐nitrobenzoic acid (p‐ and m‐NBA) were prepared on the thin metal film. The system was then examined by infrared spectroscopy attenuated total reflection (IR–ATR). It was found that through the interaction between the metal islands film and the electric field of the incident IR beam the infrared absorption of the molecule layers adsorbed on the islands was enhanced by a factor of 17. The surface‐enhanced IR absorption (SEIRA) also presents a selection rule. This method was then used to study the surface modification with O₂ and NH₃ plasma and the plasma polymerization of allylamine. This is the first time that SEIRA has been used in plasma investigations. A model is provided to explain the interactions between the metal islands film and the electric field of the incident IR beam in the SEIRA. The in‐plasma‐built functional groups can be further used to graft biofunctional molecules for the biomedical industry. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1231–1237, 1999     

Fe(II) adsorption onto natural polymers derived from low‐grade lignites

In comparison with conventional chemical treatment methods for Fe(II) ions, adsorption and ion exchange are considered more easily applicable and economical, depending on the material used. Polymeric materials are the examples used in these commonly applied removal processes. In this study, the adsorption of Fe(II) ions from aqueous solutions onto two different natural polymers, insoluble humic acids (IHAs) extracted from low‐grade lignites from Beysehir and Ermenek (in the central Anatolia region, Konya, Turkey), was investigated. The IHAs were synthesized through a series of acid–base reactions, and the obtained precipitates were chemically stable and had about 40% humic matter together with functional carboxyl and hydroxyl groups. The effects of the time and initial metal concentration on the effectiveness of the IHAs for Fe(II) adsorption were determined through batch experiments; the adsorption isotherms and capacities were calculated. The IHAs were effective, with capacities of 59 mg/g for the Beysehir IHA and 57 mg/g for the Ermenek IHA, for Fe removal under neutral pH conditions. The adsorption followed mainly a Freundlich isotherm for both IHAs, and the calculated adsorption rates were 0.86 for the Beysehir IHA and 0.81 for the Ermenek IHA. This indicated that the effectiveness of the Beysehir IHA was slightly higher than that of the Ermenek IHA. The results confirmed the real possibility of the practical application of IHAs for the separation of Fe(II) in aqueous systems. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Anisotropy in nanocellular polymers promoted by the addition of needle‐like sepiolites

This work presents a new strategy for obtaining nanocellular materials with high anisotropy ratios by means of the addition of needle‐like nanoparticles. Nanocellular polymers are of great interest due to their outstanding properties, whereas anisotropic structures allow the realization of improved thermal and mechanical properties in certain directions. Nanocomposites based on poly(methyl methacrylate) (PMMA) with nanometric sepiolites are generated by extrusion. From the extruded filaments, cellular materials are produced using a two‐step gas dissolution foaming method. The effect of adding various types and contents of sepiolites is investigated. As a result of the extrusion process, the needle‐like sepiolites are aligned in the machine direction in the solid nanocomposites. Regarding the cellular materials, the addition of sepiolites allows one to obtain anisotropic nanocellular polymers with cell sizes of 150 to 420 nm and cell nucleation densities of 10¹³–10¹⁴ nuclei cm^?3 and presenting anisotropy ratios ranging from 1.38 to 2.15, the extrusion direction being the direction of the anisotropy. To explain the appearance of anisotropy, a mechanism based on cell coalescence is proposed and discussed. In addition, it is shown that it is possible to control the anisotropy ratio of the PMMA/sepiolite nanocellular polymers by changing the amount of well‐dispersed sepiolites in the solid nanocomposites. © 2019 Society of Chemical Industry     

Synthesis of a photo‐crosslinked stable nonlinear optical polymer and application to external electro‐optic measurement

A photo‐crosslinked side‐chain second‐order nonlinear optical polymer was synthesized with bis‐phenol‐A as the polymer backbone, p‐nitroaniline as the chromophore and cinnamyl group as the photo‐sensitizer. The characterization of the polymer was made by nuclear magnetic resonance, infrared, ultraviolet‐vis, and dynamic mechanical analysis methods. An electro‐optic film was obtained by spin coating of the polymer and corona poling then photo‐crosslinking reaction. An external electro‐optic measurement system was established based on the film and reflective light path configuration, and successfully applied to measure the electrical signals propagating on the under‐test circuits. The poled and crosslinked film showed high glass transition temperature (160°C) and improved chromophore orientation stability. The measuring principle was analyzed by electro‐optic tensor matrix and index ellipsoid methods. The results showed that the designed polymer film had the linear electro‐optic effect, the voltage sensitivity of the system was measured to be 5 mv/ at the condition of 1 kHz input signal. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1506–1512, 2000     

A method to assess downward flame spread and dripping characteristics of fire‐retardant polymer composites

A method is described to assess the flame retardancy of polyethylene composites by measuring both their downward flame spread rates as well as their combined melting and dripping rates on rectangular rods, ignited at their top. The composite materials were produced by mixing pulverized polymer with organic additives of differing particle sizes, shapes, and mass fractions. The resulting mix was melted in a mold, and then it was solidified into rods. The additives were carbonaceous solids with particle sizes spanning from tens of nanometers to tens of micrometers. The mass fraction of the additives in the polymer matrix varied from 1 to 5 wt%. Upon ignition of the upper tips of the polymer composite rods, the downward flame spread rate and the melting and dripping rate were separately assessed by measuring their mass loss and their heights. The addition to polyethylene of finely sized carbonaceous additives at mass fractions of 4 to 5 wt% proved effective at significantly slowing down its downward flame spread by drastically hindering its dripping tendency. The effectiveness of the additives increased with increasing their mass fraction and decreasing their particle size. High mass fractions of carbon additives resulted in wicking, which can enhance radiatively the heat transfer.     

Langmuir and Langmuir–Blodgett films of low‐bandgap polymers

Low‐bandgap conjugated polymers have provided a considerable increase in organic photovoltaic efficiencies, however, an understanding of class‐specific nanostructures, necessary to further improve device qualities, remains scarce. Their self‐assembly and associated electronic behaviors in Langmuir?Blodgett (LB) films are used here to provide relationships specific to each polymer, clarifying their structure?property characteristics. The behavior of two low‐bandgap polymers based on cyclopentadithiophene (PCPDTBT) and dithienosilole (Si‐PCPDTBT) units in the Langmuir trough were investigated and it is shown that it is possible to fabricate nanostructured films of low‐bandgap polymers on solid substrates with the LB deposition technique. The polymers were mixed with amphiphilic molecules at well‐defined concentrations to improve the formation of the LB films. The polymers were also deposited by drop‐casting and LB techniques onto interdigitated electrodes to evaluate their electrical properties, and the LB films were characterized for their optical and morphological properties. It was found that both LB and drop‐cast films of PCPDTBT showed higher electrical conductivities than those of Si‐PCPDTBT. Importantly, LB films resulted in higher electrical conductivities – by an order of magnitude ? compared to their equivalent mixtures with stearic acid in drop‐cast films, although drop‐cast films without stearic acid gave higher conductivities. This fine‐tuning of the molecular architectures of the films is thus demonstrated to directly affect the physical properties and may lead to an improvement in device efficiencies in future applications. © 2018 Society of Chemical Industry     

Determination of the formaldehyde‐to‐phenol molar ratios of resol resins by infrared spectroscopy and multivariate analysis

The formaldehyde/phenol (F/P) ratios of resol resins were successfully predicted by the recording of infrared (IR) spectra of both calibration and analyzed resins and by a multivariate analysis technique. In the creation of applicable models, the best correlating IR spectral areas were found between 1800 and 700 cm^?1. The positive effects of the increasing replicates and the omission of first‐derivative preprocessing on model quality were proven by systematic testing. The characteristic statistical parameters were acceptable when the resin was similar to the calibration resins. Although the calibration samples had narrow F/P molar ratios (2.00–2.40), or a particular urea content or alkalinity, the best calibration model could also successfully predict the F/P molar ratios of resins with greater F/P ratios, higher urea contents, and lower alkalinity. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3582–3586, 2003     

A study of pyridinium‐type functional polymers. III. Preparation and characterization of insoluble pyridinium‐type polymers

The copolymers of 4‐vinylpyridine (4VP), styrene (St) and divinylbenzene (DVB) with varied compositions, P(4VP‐St‐DVB), were synthesized by suspension polymerization using 2,2′‐azobisisobutyronitrile (AIBN) as an initiator. The insoluble (crosslinked) pyridinium‐type polymers in benzyl–pyridinium bromide form, which possess various macromolecular chain compositions, were prepared by the reaction of each P(4VP‐St‐DVB) with benzyl bromide (BzBr), respectively. By using different halohydrocarbon RX in the quaternization of P(4VP‐St‐DVB), the insoluble pyridinium‐type polymers with various pyridinium group structures were obtained. The structures of P(4VP‐St‐DVB) and its quaternized product Q‐P(4VP‐St‐DVB) were identified by FTIR. The 4VP content in each copolymer P(4VP‐St‐DVB) was measured by nonaqueous titration; and the pyridinium group content (C_q) in each Q‐P(4VP‐St‐DVB) sample was determined by means of the back titration manner in argentometry and/or the elemental analysis method, respectively. In addition, the particle structure and the surface morphology of the thus‐prepared polymer were observed using SEM. According to a series of experimental results, the preparation and characterization of insoluble pyridinium‐type polymers are analyzed and discussed. This work can prepare the ground for a study on the antibacterial activity of insoluble pyridinium‐type polymers. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 668–675, 2000     

Hydroxyethyl chitosan‐g‐poly(acrylic acid‐co‐sodium acrylate) superabsorbent polymers

A novel hydroxyethyl chitosan‐g‐poly(acrylic acid‐co‐Sodium Acrylate) (HECTS‐g‐(PAA‐co‐PSA)) superabsorbent polymer was prepared through graft copolymerization of acrylic acid and sodium acrylate onto the chain of hydroxyethyl chitosan. The structure of the polymer was characterized by FTIR. By studying the water absorption of the polymer synthesized under different conditions, the optimal conditions for synthesizing the polymer with the highest swelling ratio was defined. This superabsorbent polymer was further treated by the solvent precipitation method and by the freeze‐drying method. We found that the water absorption rate of the treated polymer was greatly increased and the microstructure of the treated polymer was changed from small pores to loose macro pores. The swelling processes of the polymers before and after modification fit first‐order dynamic processes. The amount of the residual acrylic acid was greatly decreased after treatments. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Molecular orientation–photoconductivity relationship study of phthalocyanine polymer‐oriented thin films

The molecular orientation–photoconductivity relationships of several kinds of phthalocyanine polymer (PPc)‐oriented thin films have been studied in double‐layered photoreceptor devices, where the charge‐generation layers (CGLs) are phthalocyanine polymer‐oriented thin films and the charge‐transportation layers (CTLs) are composed of hole transporting materials of tetraphenyl benzidine or hydrazone. The oriented thin films containing PPc dispersed in polyvinyl difluoride (PVDF) were prepared by the electric field orientation. The results showed that the photosensitivities of the phthalocyanine polymer (PPcs)‐oriented thin films were higher than those of the unoriented PPcs thin films, and varied with their molecular structures and the molecular stacking in the films. This was thought to be due to the molecular orientation effect, which was demonstrated by the analyses of the polarized fluorescence, DSC, FTIR reflection absorption spectroscopy (FTIR‐RAS), and angle‐dependent XPS. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2331–2339, 2000     

Well‐defined polymers containing 1,3‐dichloro‐tetra‐n‐butyl‐distannoxane moiety: Synthesis,mechanism, and applications in catalysis

A series of well‐defined different chain lengths polymers, which contain the organometallic 1,3‐dichloro‐tetra‐n‐butyl‐distannoxane core in the main chain, was obtained in one‐pot via a novel 1,3‐dichloro‐tetra‐n‐butyl‐distannoxane (complex A )/azobisisobutyronitrile (AIBN) initiating system used in reverse atom transfer radical polymerization of styrene in different concentrations. The introduction of organotin complex A was supported by ¹H‐NMR, ¹³C–NMR, and the Inductive Coupled Plasma Emission Spectrometer analysis of the organotin‐containing polymer. Moreover, the mechanism of polymerization was investigated by changing the ratio of complex A to AIBN. It was concluded that the complex A not only acted as an important part of the initiator system but also introduced the functional organometallic group into the polymer chain. Additionally, the organotin‐containing polymer could be used as catalyst for esterification, and the reaction products' conversion could reach high up to 99% and does not decrease after four successive cycles. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Modeling the displacement in three‐layer electroactive polymers using different counter‐ions by a phase transformation approach

The use of three‐layer electroactives polymers is becoming more widely known among researchers and engineers because of their potentials to become mechanical actuators. The up‐to‐date research and development in the Nafion^®/Metal composites has given some fundamentals, preparation techniques, and modeling of the phenomena regarding the deformation of the material from different scientific point of view. This gives the opportunity to propose correlations for modeling the phenomena present in these materials by different approaches. A constitutive model for the bending deformation of a Nafion^® Ionic Polymer‐Metal Composite (IPMC) was formulated based on an approach that represents, analogically, a phase transformation inside the base polymer and combines it with the bending of a beam in order to predict the displacement when the material is subject to an electrical input. The model was solved and evaluated for five different types of counter‐ion systems. Experimental data was used to solve the parameters within the model. The results of the solved model gave a good fitting of the experimental data and are shown for different voltage and frequency conditions in all five ionic systems. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Nano‐scaled ordering of hyperbranched and star‐hyperbranched polymers

Hyperbranched polystyrenes (HPS) were prepared by living radical polymerization of 4‐vinylbenzyl N,N‐diethyldithiocarbamate (VBDC) as an inimer under UV irradiation. These HPS exhibited large amounts of photofunctional diethyldithiocarbamate (DC) groups on their outside surfaces. We derived star‐HPS (SHPS) by grafting from such HPS macroinitiator with methyl methacrylate (MMA) or ethyl methacrylate (EMA). The ratios of radius of gyration to hydrodynamic radius R_g/R_h for HPS and SHPS in tetrahydrofuran (THF) were in the range of 0.74–0.90 and 1.05–1.12, respectively. HPS and SHPS behaved in a good solvent as hard and soft spheres, respectively. We demonstrated the structural ordering of both branched polymers in THF through small‐angle X‐ray scattering (SAXS), by varying the polymer concentration. As a result, HPS and SHPS formed face‐centered‐cubic (fcc) and body‐centered‐cubic (bcc) structures, respectively, near the overlap threshold (C*). © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3340–3345, 2006     

Poly(2‐alkyloyloxyethylacrylate) and poly(2‐alkyloyloxyethylacrylate‐co‐methylacrylate) comblike polymers as novel phase‐change materials for thermal energy storage

A series of poly(2‐alkyloyloxyethylacrylate) and poly(2‐alkyloyloxyethylacrylate‐co‐methylacrylate) polymers as novel polymeric phase‐change materials (PCMs) were synthesized starting from 2‐hydroxyethylacrylate and fatty acids. The chemical structure and crystalline morphology of the synthesized copolymers were characterized with Fourier transform infrared and ¹H‐NMR spectroscopy and polarized optical microscopy, respectively, and their thermal energy storage properties and thermal stability were investigated with differential scanning calorimetry and thermogravimetric analysis, respectively. The thermal conductivities of the PCMs were also measured with a thermal property analyzer. Moreover, thermal cycling testing showed that the copolymers had good thermal reliability and chemical stability after they were subjected to 1000 heating/cooling cycles. The synthesized poly(2‐alkyloyloxyethylacrylate) polymers and poly(2‐alkyloyloxyethylacrylate‐co‐methylacrylate) copolymers as novel PCMs have considerable potential for thermal energy storage and temperature‐control applications. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Accelerating effect of NaNO2 on the polymer plating of 6‐substituted‐1,3,5‐triazine‐2,4‐dithiol mono sodium salts

Organic polymer plating properties of 6‐substituted‐1,3,5‐triazine‐2,4‐dithiol mono sodium salts were investigated in the presence of various supporting electrolytes. Among these, the NaNO₂ supporting electrolyte greatly accelerated the film formation rate in polymer plating. The accelerating effect of NaNO₂ was further confirmed by comparing plating potentials in the presence of NaNO₂ and Na₂CO₃. The potentiostatic polymer plating of DAN in the presence of the NaNO₂ supporting electrolyte took place in the potential range of 1.65–1.8 V (compared against saturated calomel electrode reference). Film formation was influenced by such factors as the pH of solution and both the chemical structure and the concentration of triazine dithiol. In polymer platings, NO anions are thought to be electrochemically oxidized to yield NO radicals and these radicals react with DAN to yield new thiyl radicals. The thiyl radicals in the DAN molecules couple with each other by means of disulfide bonds, resulting in the growth of polymer film. Organic polymer plating films are shown to contain disulfide bonds, monosulfide bonds obtained by the reaction between allyl groups and thiyl radicals, and network chains. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2300–2309, 2001     

Evaluating effects of applying different kinetic models to pyrolysis modeling of fiberglass‐reinforced polymer composites

This research evaluates the effects of applying different kinetic models (KMs), developed based on thermal analysis using thermogravimetric analysis data, when used in typical 1D pyrolysis models of fiberglass‐reinforced polymer (FRP) composites. The effect of different KMs is isolated from the FRP heating by conducting pyrolysis modeling based on measured temperature gradients. Mass loss rate simulations from this pyrolysis modeling with various KMs show changes in the simulations due to applying different KM approaches are minimal in general. Pyrolysis simulations with the most complex KM are conducted at several heat flux levels. Mass loss rate comparison shows there is good overlap between simulations and the experimental data at low incident heat fluxes. Comparison shows there is poor overlap at high incident heat fluxes. These results indicate that increasing complexity of KMs to be used in pyrolysis modeling is unnecessary for these FRP samples and that the basic assumption of considering thermal decomposition of each computational cell in comprehensive pyrolysis modeling as equivalent to that in a thermogravimetric analysis experiment becomes inapplicable at depth and higher heating rates. Copyright © 2014 John Wiley & Sons, Ltd.     

Synthesis and characterization of accordion main‐chain azo‐dye polymers for second‐order optical non‐linearity

New type accordion polymers with azo‐dye chromophores as the major segments (up to 70% by weight) of the main chain for second optical non‐linearity (NLO) are designed and synthesized by the Knoevenagel polycondensation between bis(carboxaldehyde) containing azobenzene and bis(cyanoacetate) comonomers. Several important properties for NLO application, such as solubility and thermal stability, are investigated, and the effects of linkage groups on the physical properties of polymers are also discussed in some detail. Poled films of one of these polymers show a relatively high resonant d₃₃ value of 33 pm V⁻¹ by second harmonic generation (SHG) measurement, and their order parameter, which is determined to be 0.20 by UV–vis measurement, keep almost constant for 240 h at ambient temperature. © 2000 Society of Chemical Industry     

Co‐delivery of methotrexate and doxorubicin via nanocarriers of star‐like poly(DMAEMA‐block‐HEMA‐block‐AAc) terpolymers

Combined therapy is a promising strategy for clinical cancer treatment with synergistic effects. The purpose of the work reported was to evaluate a smart nanocarrier for co‐delivery of doxorubicin (DOX) and methotrexate (MTX). Since star‐like nanocarriers can load a high dose of drugs with various properties, we developed star polymer nanomicelles based on poly[(2,2‐dimethylaminoethyl methacrylate)‐block‐(2‐hydroxyethyl methacrylate)‐block‐(acrylic acid)] having potential for multi‐drug delivery. The nanomicelles demonstrated high encapsulation efficiency, i.e. 97.1% for DOX and 79.5% for MTX. To this end, the star‐like terpolymers were synthesized via atom transfer radical polymerization with pentaerythritol as an initiator. The micellar properties and dual stimuli‐responsive behaviour of the terpolymers were investigated using transmission electron microscopy, field emission scanning electron microscopy and dynamic light scattering measurements, concluding that this co‐therapy offers a promising approach for cancer treatment. © 2019 Society of Chemical Industry