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This paper aimed to examine how the amphoteric conditioner poly (acrylamide-′acryloyloxyethyl trimethyl ammonium chloride −2-acrylamido-2-methyl-propane sulfonate) (PADA) with different anionic degrees (AD) affected the properties of sludge flocs in the conditioning. The floc properties were characterized by morphological parameters (floc size distribution, fractal dimension, specific surface area, and pore volume), physical properties (floc strength and surface charge density), and chemical constituents (Fe3+, Al3+ and extracellular polymeric substances (EPS), including the polymeric proteins and carbohydrates). The results of this investigation revealed that (1) morphological properties of flocs were associated with anionic degree, particularly in the range of 0-4%, where the anionic degree led to a shift of the particle size toward groupings of larger diameter, meanwhile better regularity and increased compactness of floc structure formed. (2) The introduction of the anionic groups indeed had bad effects on flocs in terms of its stability and charge neutralization, but the downtrend could be inhibited by adjusting the anionic degree of polymer to a reasonable level. (3) The dissolved EPS for sludge followed a role of decreasing firstly then increasing with increased anionic degree, but the content of bound EPS kept nearly constant. (4) The polymer with anionic groups had apparent effects on enrichment of metal ions. POLYM. ENG. SCI., 57:197-205, 2017. © 2016 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Polymer surface modification that mimicks natural behaviors has been a subject of great interest. Fabrication of polymer nanofiber arrays with various applications has been studied intensively. Avoidance of chemical solvents, reduction of processing time, improvement of the nanofiber size distribution and aspect ratios, and improvement of reproducibility have been sought for industrial value creation. This study examines an alternative fabrication methods for polymer nanofiber arrays using a combination of anodic aluminum oxide (AAO) nanoporous template and thermal nanoimprinting lithography for simple, precise processing. Based on those results, nanofiber arrays were fabricated with 40-µm-thick film and 50-100 nm fiber diameter polystyrene (PS) and polypropylene (PP). For this study, 50-nm diameter PS nanofibers with 50 µm maximum length and a maximum aspect ratio of 1,000 were produced in addition to PP nanofibers having 130 µm maximum length and an aspect ratio of 2,600. The nanofiber lengths were affected considerably by molten polymer flow related to imprint processing conditions, polymer properties, AAO properties, and surface wettability between AAO and molten polymers. Moreover, AAO nanoconfinement demonstrated molecular orientation alignment of polymers that affect thermal properties, crystallinity, and mechanical properties of the obtained polymer nanofiber arrays. POLYM. ENG. SCI., 57:214-223, 2017. © 2016 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

By analyzing the breakage of composites from a new perspective, the tensile strength of composites filled with spherical particles is studied in this article. A large number of experimental data are summed up, and a novel form of formula that can predict the tensile strength of composites is put forward. This form of formula focuses on the composites that possess strong adhesion strength between particles and polymer matrix. High particle volume fraction results in a phenomenon that the particles in composites have a tendency to aggregate. So, the influence of the particle aggregation is also studied in this article. A critical particle volume fraction is proposed to describe that at what value of particle volume fraction the clusters begin to form. And an aggregation factor is put forward to describe the extent that the clusters diminish the composite's tensile strength. A good agreement between the results of the prediction by this article and the experimental data in many references has been found, which validates the accuracy of the theory. POLYM. ENG. SCI., 57:137-143, 2017. © 2016 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

We present a comparative study of the nanomorphology of spray and spin coated films of a blend of thieno[3,4- b]-thiophene/benzodithiophene (PTB7) semiconducting polymer and [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM). The surface morphology and inner structure of these films are investigated with optical microscopy, atomic force microscopy (AFM), and grazing incidence wide-angle X-ray scattering (GIWAXS). The spray coated PTB7:PC71BM films exhibit significant differences in the molecular packing compared with their spin-coated counterparts. Only very weak order is observed in the spray-coated films as compared to well-defined ordered periodic lamellar structure and π-π stacking of the PTB7 polymer of the spin-coated systems. This difference in the resulting nanomorphology is related to the different structural formation mechanisms in the two deposition techniques. POLYM. ENG. SCI., 56:889-894, 2016. © 2016 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

The effect of deformation history (hysteresis) on transient capillary rheometric data was studied compared to conventional assumptions regarding steady state data. The factors studied were: the position instrumentation, the pressure instrumentation, entrance and exit effects, polymer melt compressibility, pressure dependence of the viscosity, and polymer melt viscous heating. Statistical analysis of variance was performed to statistically determine the sources of variance to specific degrees of confidence. The polymer melt compressibility, pressure dependence, and viscous heating were found to be statistically significant contributors of the observed variation at the 95% confidence level; the capillary length and instrumentation were not found to be significant. The results indicate that the transient behavior can vary the modeling of the apparent viscosity in a significant manner such that the model fidelity and model coefficients may vary substantially. Hence, polymer melt compressibility, pressure dependence, and viscous heating should be considered during rheological model fitting to increase model fidelity and predictive accuracy in end-use. POLYM. ENG. SCI., 56:895-904, 2016. © 2016 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

The objective of this work is the synthesis of a polypropylene/ethylene-propylene-rubber (TPO)/polylactide (PLA)/compatibilizer (PVM) blend to reduce the elongation at break of TPO by blending TPO with brittle PLA. Three TPO types with different viscosities were melt blended with PLA and an ethylene/ n-butylacrylate/glycidyl methacrylate terpolymer (PVM) as reactive compatibilizer. All blends had a constant PLA amount of 30 wt%. Two parameters were varied in the experiments, viscosity of the TPO types, and amount of PVM used in the blends. Both parameters played important roles in reducing the nominal elongation at break compared to pure TPO foils and influencing the phase morphology of extruded blend foils. The nominal elongation at break could be reduced by 100-150% through blending TPO with PLA and PVM. Characterization regarding the blend morphology, especially the size and shape of the dispersed PLA phase in the TPO matrix was done by Environmental Scanning Electron Microscopy (ESEM) images. Investigations of the morphology showed that size and shape of dispersed PLA phases are dependent on the viscosity ratios of the blend components and on the amount of compatibilizer in the blend. AFM images of the polymer blends reveal soft rubbery layers around the dispersed PLA phases. POLYM. ENG. SCI., 56:905-913, 2016. © 2016 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Enthalpy recovery measurement was used to study the physical aging behavior of a polystyrene. The aging experiments at temperatures ( TA) near Tg were conducted with aging times ( tA) ranging from several minutes to several days. The recovered enthalpy, Δ H( tA, TA), increased with tA, and then a plateau value of Δ Hplate appeared in the long time aging experiment. The master curve was successfully constructed concerning the normalized relaxation isotherm of ϕ for the temperature range of Tg−16 < TA < Tg−8 if Δ Hplate was used to calculate the normalized term. This implies that the enthalpy relaxation evolves with the same molecular dynamics in respective TA. The shift factor in the master curve was interpreted in terms of the WLF (Williams-Landel-Ferry) equation to determine the coefficients for the superposition of ϕ- tA curves. A smaller value was found in c1 in comparison with those reported in the literature on polystyrene viscoelastic data, which was discussed in terms of temperature dependence of the relaxation rate in the enthalpy decay. POLYM. ENG. SCI., 56:561-565, 2016. © 2016 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Hypercrosslinked polymers (ILHCPs) incorporated with imidazolium salts were prepared using 4-vinylbenzyl chloride, divinylbenzene, and imidazole ionic liquid monomers with various alkyl groups and anions by free radical copolymerization and Friedel-Crafts alkylation reaction. The structures of ILHCPs were characterized by using FT-IR, solid state 13C CP/MAS NMR spectroscopy, TGA, and gas adsorption. ILHCPs exhibit excellent capability of CO2 adsorption compared with that of nonfunctional hypercrosslinked polymers (HCPs), although both the BET surface area (447-667 m2/g) and pore volume (0.24-0.28 cm3/g) of ILHCPs are less than HCPs. The synergistic effect from mirco/mesopore structures and imidazolium salts are proved to play a key role in enhancing the CO2 adsorption capability and selectivity over other gases for ILHCPs. It can be found that the imidazolium salts content in HCPs is more important compared with the pore texture for adsorbing CO2. An optimal molar content of imidazolium salts groups is found to be 10.5% with the maximum CO2 uptake capability of 7.56 wt% and best CO2 adsorption selectivity (CO2/N2) of 47.9/1 (273 K, 1 bar), while those of the HCPs are only 5.93 wt% and 27.9/1. Such results strongly suggest that ILHCPs can be promising applied in selective CO2 separation. POLYM. ENG. SCI., 56:573-582, 2016. © 2016 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Many polymers are extruded through blown film dies to produce both monolayer and multilayer films. A common type of die in use today to produce blown films is the spiral mandrel die. This type of die can be used effectively for many polymers in structures containing up to approximately ten layers. This paper will discuss the development of new technology using a feedblock and layer multipliers in combination with encapsulation technology and a unique film die to produce microlayer blown film structures with significantly larger numbers of layers than can be produced using conventional blown film technology. POLYM. ENG. SCI., 56:598-604, 2016. © 2016 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

This review article deals with latest literature studies on the potential use of polymer ultrathin and nanosized structures obtained by electrospinning to design novel engineered materials with bioactive properties. The electrofluidodynamic process offers the option to form high-performance bioactive systems based on polymer yarns of nanofibers or coatings of nanobeads with high surface-to-volume ratios. The electrospun and electrosprayed nanostructures can be further functionalized by encapsulation with bioactive fillers and substances. For both scenarios, the resultant polymer nanostructures present unique bioactive properties capable of providing a beneficial impact over human's health and with improved and advanced performance for biomedicine, pharmaceutics, nutrition, bioengineering, and healthcare applications. These novel functional materials attained by the electrospinning technology can be of interest for many bioactive applications such as functional food design, food packaging, functional coatings, controlled delivery of drug solutions and, mainly, tissue engineering. This article is purposely designed to gather, for the first time, most recent and promising multi- and inter-disciplinary developments based on electrospun systems for bioactive applications, which are either bioactive material concepts or can be advantageously applied to become such. POLYM. ENG. SCI., 56:500-527, 2016. © 2016 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

A comparative study of scratch behavior of single- and bi-layer hard coatings deposited on poly(methyl methacrylate) substrates was investigated. Trimethylolpropane triacrylate (TMPTA) and pentaerythriol triacrylate (PETA) with different chemical structure were chosen as a top layer for bilayer coatings, and soft base layer was introduced with varying thickness from 5 to 15 µm to demonstrate effect of soft base layer thickness on scratch properties. The scratch properties were characterized by a progressive load scratch test in terms of the onset of critical normal load for coating failure (i.e., crack and delamination). The introduction of soft base layer caused increase of critical normal load for the onset of coating failures, which implied the excellent scratch properties in both TMPTA and PETA systems. Moreover, it was found that thicker soft base layer led to better scratch properties. POLYM. ENG. SCI., 56:528-535, 2016. © 2016 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Microorganisms on components should be killed through sterilization in order to ensure the safe use of medical products for patients. Therefore, polymer parts are treated particularly with gamma radiation, ethylene oxide, or superheated steam; such treatment may result in a modified structure or the degradation of the polymer. The present paper shall demonstrate how the mechanical properties of tension bars and welded samples of polypropylene and polycarbonate change during the sterilization procedure. The resulting changes in the structure and the degradation respectively will be analyzed by Fourier transform infrared spectroscopy (FTIR) and Differential Scanning Calorimetry (DSC) and structural property relationships shall be derived. The conducted analyses showed that the changes in the mechanical properties depend on the sample, the sterilization procedure, and the corresponding polymer; and that those changes must be considered when designing the respective products. POLYM. ENG. SCI., 56:536-540, 2016. © 2016 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

A review of nucleating agent (NA) types and their effect on crystallization in high-density polyethylene (HDPE) is presented. The focus is on methods to improve the physical properties of HDPE due to its widespread use in commercial applications and high volume use in typical industrial processes including extrusion, injection molding, and blow molding. The crystallization process in HDPE significantly affects its final optical, mechanical, and thermal properties. The addition of NAs affects the physical properties of HDPE by controlling the crystallization from the melt state. Specific NAs improve properties such as clarity, cycle time, and modulus. NAs are more widely developed for polypropylene (PP) than HDPE as its slower crystallization rate allows greater control in achieving property improvements. While certain NAs are effective in improving property characteristics in HDPE, greater control over the crystallization process would achieve further improvements in specific properties. Research has progressed in identifying effective NAs for HDPE, though the magnitude of the effects remains lower than those generally observed in PP. Inorganic and organic NAs are reviewed with an emphasis on the mechanisms by which they function. Fundamentals of polymer crystallization and modeling kinetics during both isothermal and nonisothermal studies provide the necessary framework for characterizing the effects of a NA in HDPE. Finally, the interactions between HDPE, NA, and industrial processing conditions as related to practical applications are discussed. POLYM. ENG. SCI., 56:541-554, 2016. © 2016 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

The present article reports an approach for the modification of hydrophobic polydimethylsiloxane (PDMS) with low molecular weight hydrophilic polyvinylpyrrolidone (PVP) via solution blending method to develop new PDMS-based materials with improved mechanical performance and wettability which can be used in many biomedical applications. The influence of dimethyldichlorosilane treated fumed silica (FS) on physico-mechanical properties of PDMS-PVP blends were investigated and analyzed. There was the significant improvement in mechanical, dynamic mechanical and thermal properties of PDMS-PVP blends, whereas, transparency and contact angle were slightly decreased after incorporation of FS into PDMS-PVP blends. Scanning electron microscopy revealed that the fourfold reduction in the average domain size of the dispersed PVP in the PDMS matrix in the presence of compatibilizer (PDMS-PEO block copolymer) when compared with the uncompatibilized PDMS-PVP blend morphology. By incorporation of FS into the neat PDMS matrix, the onset of degradation ( Ti), the maximum rate of degradation ( Tmax) and overall thermal stabilities increased significantly. On the other hand, by the addition of FS into to PDMS-PVP blends, the Ti and Tmax remains unaffected, but overall thermal stabilities increased significantly. PDMS-PVP blends exhibited low contact angle (∼45°) which confirmed the formation of the hydrophilic surface. POLYM. ENG. SCI., 56:491-499, 2016. © 2016 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

This paper deals with the study of new interfacial instabilities, called 'grainy' defects, in coextrusion process of reactive multilayer polymers. The main objective was to better understand this phenomenon since no help can be found in the literature. The fundamental approach from a micro-scale to a macro-scale involves the study of relationships between polymer structure, processing, and interfacial properties. The influence of these parameters on the generation of 'grainy' defects during coextrusion has been assessed in correlation with physicochemical properties. Through this work, rheological properties and the interfacial morphology between tie and barrier layers have been investigated by shear stress relaxation experiments and transmission electronic microscopy, respectively. Depending on the reactive polymers, the interfacial coupling was found to significantly alter the stress relaxation behavior by extending the relaxation time and generating an interfacial roughness. Hence, relations between the copolymer architecture, the relaxation process, and the interfacial morphology were established in correlation with the generation of grainy defects in coextrusion process. POLYM. ENG. SCI., 55:2542-2552, 2015. © 2015 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

A process for making high-density polyethylene (HDPE) single-polymer composites (SPCs) by insert injection molding was investigated. HDPE SPCs with relatively good tensile and interfacial properties were prepared within a short cycle time within a temperature range of 40°C. Melt-spun HDPE fibers were made from the same resin as the matrix. The fibers were heat treated in silicone oil, with and without tension, to study the changes of fiber properties upon exposure to high temperature. HDPE SPCs containing about 30 wt% lab-made HDPE fabric achieved a tensile strength of 50 MPa, 2.8 times that of neat HDPE. The peel strength of HDPE SPCs increased with increasing injection temperature and achieved a maximum value of 16.7 N/cm. Optical micrographs of polished transverse cross-sections of the SPC samples showed that higher injection temperature is beneficial to the wetting and permeation properties of the matrix. Scanning electronic microscope photographs suggested good bonding and compatibility between the fibers and the matrix. POLYM. ENG. SCI., 55:2448-2456, 2015. © 2015 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

A deep understanding of the anisotropic, composite-, geometry-, and temperature-dependent coefficient of thermal expansion (CTE) of short-fiber-reinforced polymers is often needed in material development and at early stages of the design process of injection molded parts. Usually, the data available does not reflect the complex behavior and the knowledge about the influences and interactions are missing. This paper deals with a method for calculating the composite-, geometry-, and temperature-dependent anisotropic CTE of parts made from short-fiber reinforced polymers without respectively low preload to create an understanding of its origins and influential factors. Here, a good accordance between the measurements and calculations was achieved. POLYM. ENG. SCI., 55:2661-2668, 2015. © 2015 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

The thermal effects on manifold temperature uniformity and output flow uniformity are important for polymer extrusion die design. Lin and Jaluria (Lin and Jaluria, Polym. Eng. Sci., 37, 1582 (1997)) has carried out a numerical study on conjugate heat transfer for extrusion polymer flow under the assumption that the die body surface is in uniform temperature or heat transfer coefficient. In this study, we have solved the non-uniform body surface temperature as part of the simulation solutions based on heat flux boundary conditions (including radiation and convection heat transfer). The body temperature is computed in conjugated with the melt polymer flow with non-linear viscous shear heating effect. The relative tough thermal conditions are set to test uniformity of the temperature distribution on the manifold wall. We also give the results of the heat transfer effect on the flow velocity distribution. POLYM. ENG. SCI., 54:682-694, 2014. © 2013 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Electrospinning provides an effective methodology to obtain high aspect ratio polymer fibers for biomimetic applications. In this article, we evaluate the effect of topology on adhesion between aligned fibers. Polycaprolactone is electrospun using two different setups: (i) a tip collector and (ii) a flat collector. The tip collector enables the fibers to self-align. When a fiber reaches the tip collector, the next fiber is repelled by the charge they carry, forcing the fibers to deposit in a parallel arrangement. The flat collector allows the fibers to deposit at random. The adhesion between the fiber mats is measured using a T-peel test. Adhesion strength (758.7 ± 211.7 kPa) changes marginally with the peeling rate and applied pressure on the membranes. Aligned fibers exhibit higher adhesion strength between the membranes in comparison to randomly oriented nonwovens (613.1 ± 79.9 kPa). The estimated Johnson-Kendall-Roberts contact energy (83.1 ± 32.5 mJ/m²) is consistent with the range of van der Waals adhesion forces, This work shows how the adhesion between two polymer membranes can be modulated by surface topology, based on a T-peel testing setup. [ABSTRACT FROM AUTHOR]

The aim of this study was to qualitatively and quantitatively characterize the optic surface topography of unworn hydrogel contact lenses (CLs) using atomic force microscopy (AFM) analysis and methods of modern metrology. The CLs used in this study were vifilcon A (Focus® Monthly Toric Visitint#174; model, CIBA Vision Corp.). AFM analysis was performed in Tapping Mode™ in an aqueous environment. The surface roughness analysis was based on six quantitative statistical parameters: arithmetic mean deviation of the surface (Sa), root mean square deviation of the surface (Sq), skewness of the topography height distribution (Ssk), kurtosis of the topography height distribution (Sku), 10-point average of the absolute heights (Sz), and vertical distance between highest peak and lowest surface point (St). These parameters were determined across different square areas (1, 4, 9, 16, and 25µm²). The surface roughness parameter values were found to be dependent on the examined surface area. The values of Sa, Sq,¦Ssk¦, Sz, and St parameters increase with the increasing size of the scanning area, an opposite effect of that observed for the Sku parameter values. The proposed methodology might potentially have implications for the future testing of contact lens hydrophilic polymers. [ABSTRACT FROM AUTHOR]

Natural fibers such as jute fiber and biodegradable poly(lactic acid) (PLA) polymer are very good choices for environmental friendly material. Multi-gate injection is often used to meet the demand of mass production of injection moldings, therefore weld line is inevitable. The presence of weld lines not only detracts from the surface quality but also significantly reduces the mechanical strength of injection-molded parts. Although it is not always easy to completely eliminate weld lines, the weld strength could be improved through suitable adjustment of molding conditions such as melt temperature, mold temperature, hold pressure, injection speed, and so on. In this study, three kinds of pellets materials were prepared: long fiber pellets (LFT), the re-compounding pellets (RP), and LFT50:RP50 hybrid mixtures (LFT/RP). Tensile test was carried out to investigate the effect of different pellets and holding pressures on the mechanical property of welded jute/PLA specimens. And the interfacial shear strength of non-welded jute/PLA specimens was calculated with Kelly-Tyson Formula. Fiber separation and fiber dispersion in RP became better than that of LFT which resulted in a better interfacial property. Weld strength of RP and hybrid LFT/RP specimens was improved by 43.34% and 16.46% than that of LFT specimen, respectively. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

The nanometer calcium carbonate (nano-CaCO3)-filled poly- L-lactide (PLLA) biocomposites were prepared using a twin-screw extruder. The first normal stress difference of the composites were measured by means of a capillary rheometer under experimental conditions with temperatures ranging from 170 to 200°C and shear rates varying from 50 to 103 s−1. The first normal stress difference ( N1) increased roughly linearly with increasing shear stress (τw). The sensitivity of the N1 to τw increased with an increase of the die length--diameter ratio, and the N1 value varied slightly with the filler weight fraction (ϕf) as test temperature was constant. When the shear stress was fixed, the N1 reached a minimum value for ϕf = 1%. The values of the N1 of the composite melts decreased roughly linearly with a rise of temperature when the shear rate was constant. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

The decomposition of azodicarbonamide, used as foaming agent in PVC-plasticizer (1/1) plastisols was studied by DSC. Nineteen different plasticizers, all belonging to the ester family, two being polymeric (polyadipates), were compared. The temperature of maximum decomposition rate (in anisothermal regime at 5 K min−1 scanning rate), ranges between 434 and 452 K. The heat of decomposition ranges between 8.7 and 12.5 J g−1. Some trends of variation of these parameters appear significant and are discussed in terms of solvent (matrix) and viscosity effects on the decomposition reactions. The shear modulus at 1 Hz frequency was determined at the temperature of maximum rate of foaming agent decomposition, and differs significantly from a sample to another. The foam density was determined at ambient temperature and the volume fraction of bubbles was used as criterion to judge the efficiency of the foaming process. The results reveal the existence of an optimal shear modulus of the order of 2 kPa that corresponds roughly to plasticizer molar masses of the order of 450 ± 50 g mol−1. Heavier plasticizers, especially polymeric ones are too difficult to deform. Lighter plasticizers such as diethyl phthalate (DEP) deform too easily and presumably facilitate bubble collapse. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Polyaniline (PANI) nanofibers were prepared via the reaction of aniline with ammonium persulfate carried out in ethylene glycol (EG) medium without water. These purified PANI nanofibers could be dispersed in water and other polar solvents, such as ethanol, EG, and N, N-dimethylformamide, to form colloids. The morphology and structure of the PANI nanofibers were characterized and the effects of mechanical stirring on the morphology, structure, and electrical performance of PANI were investigated. The results indicated that the intermolecular H-bonding interaction between molecules of PANI and alcohol is advantageous to the one-dimensional growth of PANI, and a stirring reaction results in a lager size, a higher doping level, conductivity, degree of crystallinity, and oxidation than a nonstirring reaction. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers. [ABSTRACT FROM AUTHOR]

In this study, unsaturated polyester (UP) resin based on palm oil was synthesized. Palm oil monoglyceride (POMG) was obtained by alchoholysis process of palm oil at 230°C for 3 h. Then, POMG was treated with maleic anhydride (MA) at different ratio of POMG:MA to produce UP resin. The products were then characterized using Fourier transform infrared (FTIR) spectrometer and proton nuclear magnetic resonance (1H-NMR) spectrometer. FTIR and 1H-NMR spectrum analyses confirmed that the unsaturated group of MA was chemically attached to POMG. The activation energy of POMG/MA reaction was also studied. The results showed that the ratio of reactants and the presence of 2-methylimidazole influenced the activation energy of reaction. The prepared UP resin was mixed with 35% of styrene, 0.3% of cobalt naphthenate, and 1% of methyl ethyl ketone peroxide before it was subjected to curing process. The effect of POMG/MG ratio on swelling properties of the cured UP was studied, and the result indicated that toluene and cured UP resin were compatible. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

In this communication we report synthesis of three new donor-acceptor (D-A) type conjugated polymers carrying 1,3,4-oxadiazole moiety and thiophene unit with different side groups at its 3,4 positions (4-methoxybenzyl:P1, 3-methylbenzyl:P2 and 4-nitrobenzyl:P3) through polycondensation route using a series of newly synthesized monomers. The structures of new monomers and polymers were confirmed by NMR, FTIR spectroscopic methods followed by elemental analysis. Further, molecular weight and thermal stability were determined using gel permeation chromatography and thermogravimetric analysis. The linear optical and electrochemical properties of polymers were investigated by UV-vis absorption, fluorescence spectroscopic, and cyclic voltammetric studies. The polymers P1-P3 were found to be thermally stable and their electrochemical band gaps were determined to be 1.98, 2.14, and 2.18 eV respectively. Further their nonlinear optical properties were investigated by Z-scan method using 532 nm, 7 ns laser pulses. The results reveal that they possess good optical limiting behavior due to effective three-photon absorption (3PA) with absorption coefficient 2.5 × 10−24 m−3W2, 1.6 × 10−24 m−3W2, and 1.0 × 10−24 m−3W2. POLYM. ENG. SCI., 2013. © 2013 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Preparation and experimental studies on the phase transitions and morphology of novel polymer-dispersed liquid crystal (PDLC) mixtures of polysulfone UDEL-3000 (PSU) or its derivatives (chloromethylated polysulfone or polysulfone containing lateral phosphaphenanthrene substituent) and a phosphorus-containing liquid crystalline polymer (LCC) that exhibit isotropic/nematic/smectic-A mesophase transition were performed. The mesomorphic properties of PDLC have been investigated by differential scanning calorimetry and polarizing optical microscopy. Mesophases structures were also investigated by X-ray diffraction measurements, the diffraction pattern being in close dependence on the polysulfone structure and PDLC composition. The effect of the phosphorus content on the thermal properties was evaluated by thermogravimetric analysis. The results reveal that the composites were stable up to 337°C in air showing initial decomposition temperatures in the range of 337-368°C and a 10% weight loss in the range of 357-397°C. The presence of P in the structure of LCC leads to higher char yields at 700°C, for PDLCs composites, increasing with the content of phosphorus-containing polymer. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Electrically conducting biodegradable polymer composites made of polypyrrole (PPy) nanoparticles embedded in poly( L-lactide) (PLLA) or poly(ε-caprolactone) (PCL) are prepared by chemical oxidative polymerization. They will be used as electrical conductors for fabricating biodegradable passive resonant circuits for bioimplants. For both composites, the conductivity exhibits a percolation threshold at ∼6 wt% of PPy. Several reactants are tested, the polymerization process resulting in the highest conductivity uses iron(III)chloride hexahydrate (FeCl3), sodium dodecyl benzene sulfonate, and p-nitrophenol (pNPh), for both poly( L-lactide)-polypyrrole (PLLA-PPy) and poly(ε-caprolactone)-polypyrrole (PCL-PPy). Conductivities of 2.7 ± 0.8 S cmε1 (PLLA-PPy) and 7.8 ± 2.3 S cm−1 (PCL-PPy) are reached for a PPy content of 40 wt%. The PPy particle, observed by SEM, forms agglomerates having a size of 0.6-3.5 μm. The samples have similar PPy particle distributions over the entire cross sections. The conductivity as a function of time is investigated, being 34-70% of the initial value for samples stored in nitrogen, whereas it is less than 1% for samples stored in body-like conditions, bringing the conclusion that a biodegradable packaging will be required to protect the resonant circuits from body fluids. Finally, the biocompatibility of the polymer composites is evaluated with cytocompatibility tests on dermal human fibroblast cells, showing promising results in particular for composites having a low PPy content. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Allyloxy polyethoxy ether (APEG) and succinic anhydride were used to prepare allyloxy polyethoxy carboxylate (APEL). 8-hydroxy-1,3,6-pyrene trisulfonic acid trisodium salt (PY) was reacted with allyl chloride to produce fluorescent monomer 8-allyloxy-1,3,6-pyrene trisulfonic acid trisodium salt (PA). APEL and PA were copolymerized with maleic anhydride (MA) to synthesize PA tagged no phosphate and nitrogen-free calcium phosphate inhibitor POLY(MA-APEL-PA). Structures of PA, APEG, APEL, and POLY(MA-APEL-PA) were carried out by FTIR and 1H-NMR. Different MA : APEL mole ratios were employed for the manufacture of POLY(MA-APEL-PA) to study the effect of mole ratio on performance of POLY(MA-APEL-PA). Relationship between POLY(MA-APEL-PA)'s fluorescent intensity and its dosage was studied. The results indicate that capability of POLY(MA-APEL-PA) is heavily depended on the mole ratio of MA : APEL. Correlation coefficient r of POLY(MA-APEL-PA)'s fluorescent intensity and its dosage is 0.9999, and detection limit of POLY(MA-APEL-PA) is 0.86 mg/L. POLY(MA-APEL-PA) can be used to accurately measure polymer consumption on line besides providing excellent calcium phosphate inhibition. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Calcium nitrate (Ca(NO3)2) was used as the plasticizer to improve the properties of Poly(vinyl alcohol) (PVA). The interaction between Ca(NO3)2 and PVA was investigated by Fourier transform infrared (FTIR) spectroscopy. The influence of Ca(NO3)2 on the crystalline, thermal, and mechanical properties of PVA was studied by X-Ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), and tensile testing, respectively. FTIR studies showed that Ca(NO3)2 could strongly interact with PVA molecule and reduce the intensity of the hydrogen bonding between PVA molecules. The crystallization of PVA was interrupted and the degree of crystallinity of PVA decreased due to the strong interaction between Ca(NO3)2 and PVA. DSC studies showed that the glass transition temperature of PVA decreased with the addition of Ca(NO3)2. However, the thermal stability of PVA decreased with the addition of Ca(NO3)2. The mechanical properties of PVA was improved with the addition of Ca(NO3)2, PVA film became soft and ductile, with lower tensile strength and higher elongation at break compared with original PVA. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Electrospun poly(ethylene oxide) (PEO)/hydrated iron oxide (HIO)/sodium alginate (SA) composite nanofibers with high ultimate tensile strength of ∼31.6 ± 0.4 MPa and good morphologies, such as smooth surface appearance and average diameter of 159 ± 55 to 475 ± 55 nm, were produced in the range of 50% HIO, with significant bacteria decontamination property (92.5% removal of Vibrio vulnificus) from high specific surface area and absorption property, and 10% SA, with anti-bacterial property, based on PEO polymer content. This approach, using HIO and SA, is an effective method to possess the multi-functional properties such as anti-bacterial/bacterial decontamination properties and good mechanical property for various applications in clinical, food, environmental, biomedical, protective clothing, and other areas. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers. [ABSTRACT FROM AUTHOR]

Two new thiophene-based donor-acceptor (D-A) conjugated polymers, PDTOFV and PDTOCN, are synthesized and characterized. The polymers are readily soluble in common organic solvents and exhibit good thermal stability with onset decomposition temperature ( T d) in the range 310−330°C. Cyclic voltammetry studies revealed that polymers possess low-lying highest occupied molecular orbital (HOMO) energy levels (−5.94 eV for PDTOFV and −5.86 eV for PDTOCN) and low-lying lowest unoccupied molecular orbital (LUMO) energy levels (−3.35 eV for PDTOFV and −3.55 eV for PDTOCN). The optical band gap is calculated from onset absorption edge of the polymer film. The polymers exhibit green fluorescence with fluorescence quantum yields (ϕfl) of 38% and 42%, respectively, for PDTOFV and PDTOCN. Polymer light-emitting diodes (PLEDs) are fabricated using these polymers with a device configuration of ITO/PEDOT:PSS/polymer/Al. The device based on PDTOFV emitted green light with Commission Internationale de I'Eclairage (CIE) coordinate values of (0.25, 0.39). Whereas, the device based on PDTOCN showed white light emission with CIE coordinate values of (0.32, 0.35), which is very close to the values (0.33, 0.33) of standard white light emission. The threshold voltages of the PLEDs are determined by current density-voltage characteristics and are found to be 7.3 and 3.9 V for PDTOFV and PDTOCN, respectively. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

The structure and the thermodegradation behavior of both poly(methyl methacrylate)- co-poly(3-tri(methoxysilyil)propyl methacrylate) polymer modified with silyl groups and of intercalated poly(methyl methacrylate)- co-poly(3-tri(methoxysilyil)propyl methacrylate)/Cloisite 15A™ nanocomposite have been in situ probed. The structural feature were comparatively studied by Fourier transform infrared spectroscopy (FTIR), 13C and 29Si nuclear magnetic resonance (NMR), and small angle X-ray scattering (SAXS) measurements. The intercalation of polymer in the interlayer galleries was evidenced by the increment of the basal distance from 31 to 45 Å. The variation of this interlayer distance as function of temperature was followed by in situ SAXS. Pristine polymer decomposition pathway depends on the atmosphere, presenting two steps under air and three under N2. The nanocomposites are more stable than polymer, and this thermal improvement is proportional to the clay loading. The experimental results indicate that clay nanoparticles play several different roles in polymer stabilization, among them, diffusion barrier, charring, and suppression of degradation steps by chemical reactions between polymer and clay. Charring is atmosphere dependent, occurring more pronounced under air. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Manufacturing complex parts by the laser sintering process requires a minimum amount of energy input for consolidation of polymer particles to occur; however too much energy can result in a decline in mechanical properties. This decrease is thought to be the result of polymer chain degradation. A stable sintering region (SSR) has been proposed to describe the optimum temperature range for successful laser sintering. This article will aim to quantify the SSR for polyamide-12 by using thermogravimetric analysis (TGA) to provide a framework for identifying key laser sintering processing parameters. Weight loss with respect to temperature is the main measurement output of the TGA procedure. However, the precise temperature and thermal history of a material is difficult to quantify during the laser sintering process; instead an energy input approach has been developed. A degradation energy was calculated from the TGA data and was used in conjunction with a laser sintering formula called energy melt ratio to prescribe build parameters for laser sintered parts. The mechanical properties of these parts illustrated the effect of degradation at various levels of energy input. Implications for this work include optimizing the material selection process for polymer laser sintering materials beyond polyamide-12. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Poly(butylene succinate- co- L-lactate) (PBSL)-compatibilized poly( L-lactide) (PLLA) polymer blends with two commercial grades of polycarbonate (PC) were investigated. The capillary tests showed that the steady shear viscosity of high molecular weight PC (PC-L) was 10 times higher than that of low molecular weight PC (PC-AD) throughout the shear rate range under investigation. Morphologic examination revealed that the shape of the dispersed PC-L phase in the as-extruded blends was largely spherical, but the PC-AD phase was more like a rod and elongated further during injection molding. Notched Izod impact strength (IS) of the unmodified PLLA/PC-L blend was higher than that of PC-AD blend. The IS of modified ternary blends increased with PBSL content because of enhanced phase interaction indicated from thermal and morphologic analysis. The PBSL modification also enhanced IS more significantly in PLLA/PC-L than in PLLA/PC-AD blends. On the contrary, the heat deflection temperature (HDT) of PLLA/PC-L binary system was much lower than that of PLLA/PC-AD. HDT of PBSL-modified PLLA/PC-AD blends dropped with increasing PBSL content, which is a ductile polymer. Thermal and dynamic mechanical analysis of the ternary blends showed that individual components were immiscible with distinct Tgs for PC and PLLA and distinct Tms for PBSL and PLLA. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Boron carbonitride polymers have been arising abiding interest due to their excellent thermal and mechanical properties. In this study, a novel kind of hyperbranched polymer based on boron carbonitride skeleton, polyborazine, has been synthesized by a convenient A2+B3 approach. The chemical structure of polyborazine was confirmed by Fourier-transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), X-ray photoelectron spectroscopy (XPS), and size exclusion chromatography (SEC). FT-IR and X-ray diffraction (XRD) pattern exhibited that the boron carbonitride compound formed during the pyrolysis process contributed to the improved thermal property of polyborazine. Nevertheless, the polyborazine can catalyze the cure process of benzoxazine thermosets, and enhance the thermal stability of benzoxazine thermosets owning to the presence of the preceramic compound. The approach for fabricating reactive ceramic precursor polymer with prepolymer blend system reveals promising results for thermosets that demanding remarkable thermal stability and oxidation resistance. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

A novel polymeric superabsorbing composite was prepared using the graft copolymerization of acrylic acid (AANa, 70% neutralization with NaOH) and 2-acrylamido-2-methyl propane sulfonic acid (AMPS) onto the hydroxyethyl cellulose (HEC) [HEC- g-P(AANa- co-AMPS)], which was initiated by means of a glow-discharge electrolysis plasma rather than a chemical initiator. The composite material was characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and thermal gravimetric analysis (TGA). We obtained absorbencies of 2490 g g−1 for distilled water and of 109 g g−1 for 0.9 wt% NaCl solution. Results show that the maximum adsorption capacities for Ni(II), Cu(II), Cd(II), Pb(II), and Hg(II) from aqueous solution were 974.84, 975.43, 1535.52, 1970.47, and 1879.53 mg g−1, respectively. The adsorption isotherm followed the Langmuir isotherm model very well. Adsorption kinetics results indicate that the fast adsorption rate followed the pseudo-second-order kinetics equations. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Polyethylene (PE) composite coatings were prepared on silicon substrate by electron-beam deposition (EBD) using mixed powders of low-density polyethylene and various dopants (i.e., initiator and inhibitor) as evaporated target. The structural and morphological behaviors of PE composite coatings were investigated in dependence of initiator and inhibitor by attenuated total reflectance-Fourier transform infrared spectroscopy and atomic force microscope. Free-radical polymerization and cationic polymerization could be observed in the formation process of PE composite coatings by EBD. The initiating system of AlCl3 and benzoyl peroxide as well as the inhibiting system of diphenylamine and hydroquinone used in EBD, in comparison with conventional synthesis methods, exhibited different effect on reaction mechanism of PE composite coatings. These results might contribute to the synthesis of polymer coatings with expectant molecule structure and controllable surface morphology. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Both 80/20 and 60/40 polypropylene/poly(ethylene- co-octene) (PP/POE) blend samples were collected from four positions along a single-screw extruder, which can induce chaotic and shear mixing, respectively. Results indicated that a wide range of impact strengths was obtained as the formation of series of phase morphologies. For the 80/20 blends, the impact strength increased gradually along the extruder with shear mixing due to gradual decrease of both diameter and size distribution coefficient of droplets. Whereas the impact strengths reached the highest value at about 2/3 length of the whole screw with chaotic mixing as the formation of lamellas, then decreased as their breakup. For the 60/40 blends, the impact strength reached the highest value as the formation of the thick fibrils with shear mixing; whereas the impact strength became higher at about 2/3 length of the whole screw as the formation of thin fibrils and the highest (69 times of that of pure PP) at the end of the screw due to the formation of cocontinuous structure with chaotic mixing. Observing the fractured surface of the tested sample with cocontinuous structure revealed that a distinct deformation of the PP matrix was induced by the shear yielding during impact testing. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

The pressure establishment in the solid conveying section of a vane extruder was theoretically and experimentally studied in the present article. Based on the structural and conveying characteristics of the vane extruder, a four-plate model was developed. The effects of the device geometry (eccentricity ε and discharge port β), the polymer properties (different materials), and the operating conditions (temperature and rotating speed) on the pressure were also studied using a visual experimental device. The results showed that the experimental data were highly consistent with the theoretical data, which indicated that the theoretical model was sensible. Considering the optimization design of the device and its processing parameters, the eccentricity ε and the discharge port β of the discharge baffle should be appropriately selected, and the setting temperature of the feeding section should be set to a low value. The rotating speed of the rotor had no significant influence on the pressure establishment. In addition, the thermo-mechanical history of the vane extruder was shorter than that of the conventional screw extruder. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Nanofibers of polyvinylidene fluoride (PVDF) were prepared using solutions of PVDF with acetone and dimethylacetamide. The solutions were prepared at different concentrations (18, 21.5, and 25% wt) of PVDF. The nanofiber membranes were produced by using the Forcespinning™ method. Parameters such as the orifice size and spinneret angular velocity were varied. The produced membranes were characterized using scanning electron microscopy, differential scanning calorimetry, and X-ray diffraction to determine the effect of varying parameters in the Forcespinning™ process on fiber diameter, bead formation, thermal stability, polymorphism, and morphology of the fibers and overall structure of the membrane. It was observed that polymer concentration played a key role in fiber and bead formation; at higher concentrations (such as 25 wt%), the fiber diameter increased but the bead formation decreased. The prepared composite membranes have potential applications on separators for Li-ion batteries, ultra filtration membranes, and proton conductivity membranes for fuel cells applications. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Ultrahigh molecular weight polymers generally exhibit very high melt viscosities. They are therefore very difficult to process and require heavy-duty processing equipment. In some cases they cannot be processed at all using conventional melt processing techniques. In this study, a novel processing method called Thermoflow Forming (TFF) has been developed for manufacturing parts made from high viscosity polymers. The TFF process is based on the flow of polymer material in its thermoelastic state, between its glass transition and melting temperatures, by compressive flow thermoforming. The processing equipment consists of an upper and lower mold tool, which may be driven together, while its temperature is controlled through either induction heating or air cooling. Parts with both constant and varying wall thicknesses were successfully manufactured from ultrahigh molecular weight polyethylene and polytetrafluoroethylene (PTFE). Despite the significantly different wall thicknesses molded, the parts showed minimal warpage and no voids. Those made from PTFE exhibited a fibrillated morphological structure whose size and orientation depended on the material flow direction. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

A novel concept of microinjection molding system was designed and presented. The system was designed as a multimicroinjection module, which is matched with a vertical injection molding machine (IMM) and can be applied on commercial IMMs. A planetary gear pump was integrated in this system to complete the multi microinjection molding (MμIM). The module is fixed between the stationary platen and the mold of IMM. The plasticizing unit of the IMM provides the melt and initial pressure for the multi microinjection molding system. With this system, a commercial IMM could be upgraded to a precise microinjection machine and has the capability of precise metering for the microinjection molding. Melt flowing behavior was predicted through the 3D injection molding simulation and experiments were carried out to testify the performance of the MμIM. The injection molding performance was evaluated and the results revealed that the MμIM system could effectively realize the microinjection molding. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Three series of liquid crystalline and photocrosslinkable poly(4,4′-stilbeneoxy) alkylarylphosphates were synthesized from various 4,4′-bis( m-hydroxyalkyloxy)stilbenes ( m = 2, 4, 6, 8, 10) and arylphosphorodichloridates in chloroform by solution polycondensation method. Polarized optical microscope (POM) and differential scanning calorimetry (DSC) observations revealed that polymers containing less than four methylene spacer groups did not exhibit liquid crystalline (LC) texture, possibly due to smaller microdomain and restricted movement of the mesogen. In contrast, polymers containing more than four methylene spacer group established LC texture, which has been attributed to the larger monodomain and free movement of mesogens. Thermogravimetric analysis (TGA) data indicated that thermal stability and char yield decreased with increasing flexible methylene spacer groups, increased significantly for biphenyloxy and 1-naphthyloxy containing polymers than that of phenyloxy containing polymers ascribed to increasing aromaticity, size, and number of aromatic rings. Photocrosslinking of stilbene containing polymers has been shown to proceed via 2π-2π cycloaddition reaction by Ultra-violet (UV) and fluorescence. The rate photocrosslinking has been found to increase with increasing number of methylene group in the main chain. The aromaticity of the side chain also increases the rate of crosslinking. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Aqueous ethylenediamine (EDA) pretreatment followed by thermal stabilization of polyacrylonitrile (PAN) fibers in an oxygen rich air environment was carried out prior to the carbonization stage. The results show that the EDA pretreatment is very effective and efficient in promoting the cyclization of nitrile groups by shortening the time necessary for the development of thermally stable structure needed to withstand the high carbonization temperatures. A direct relationship between the values of density and the oxygen content is found which is believed to be due to the positive role played by the oxygen containing functional groups in the formation of ladder frame structures. Analysis of the equatorial X-ray diffraction traces shows the transformation of the original structure from a highly ordered phase to a totally disordered amorphous phase as indicated by the loss of the degree of order of the original PAN fiber. X-ray, Differential Scanning Calorimetry (DSC), and infrared conversion indices show the rapid conversion from the original open structure to highly cyclized and crosslinked polymer structure. Utilization of EDA pretreatment prior to the thermal stabilization is expected to significantly reduce the cost of the final carbon fiber manufacturing by reducing the time necessary for the thermal stabilization stage. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

The influences of carbon black (CB) structure on the percolation threshold, mechanical properties, and strain-resistivity response of polymer composites are studied. Low-density polyethylene (LDPE) and polypropylene (PP) samples were blended with five different types of CB differing in structure. Relatively low strains were studied; the maximum strain was 10%. It was found that the CB concentration for maximum strain-sensitivity of the electrical conductivity is higher for low structure carbon blacks but is essentially independent of the CB structure for medium- to high-structure carbon blacks. However, the composite containing the largest particle size carbon black clearly showed the highest strain-sensitivity to electrical conduction. The mechanical properties and sensitivity of electrical resistivity to tensile strain of the filled composites examined in the study are also presented and discussed. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

The encapsulation of aluminum nanoparticles by polyvinylidene fluoride (PVDF) was carried out in supercritical conditions via in situ polymerization. The aluminum particles possessed an average diameter of 43.7 nm. The presence of PVDF on the particles was validated by thermogravimetric analysis (TGA). This result was further approved by X-ray photoelectron spectroscopy (XPS), which showed high intensity peaks of fluorine and carbon on the particles after the encapsulation process, which are associated with the presence of hydrocarbon-based PVDF. As observed by transmission electron microscopy (TEM) images, the nanoparticles were uniformly coated by a polymer of a few nanometers in thickness. The results showed that there is a good consistency between the calculated thickness of the polymer coating and the results obtained by TEM. In addition, the effect of polymerization time on the kinetics of the reaction was investigated. Finally, it was found that the thickness of the polymer layer can be controlled by the duration of the encapsulation process. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Contact friction plays a critical role in all the major thermoforming processes for polymers. However, these effects are very difficult to measure in practice and, as a result, have received little scientific investigation. In this work, two independently developed test methods for the measurement of elevated temperature polymer-to-polymer contact friction are presented, and their results are compared in detail for the first time. One is based on a modified moving sled friction test, whereas the other uses a rotational rheometer. In each case, friction tests were conducted between two plug and two sheet materials. The results show that broadly similar coefficients of friction were obtained from the two test methods. The measured values were quite low (<0.3) at lower temperatures and typically were higher for polypropylene (PP) sheet than for polystyrene (PS). On approaching the glass transition temperature for PS (95°C) and the crystalline melting point for PP (165°C), the friction coefficients rose very sharply, and both test techniques became increasingly unreliable. It was concluded that despite their physical differences, both test techniques were able to capture the highly temperature sensitive nature of friction between polymer materials used in thermoforming. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Telecommunication facilities are protected against long-term weather exposure by certain prevention technologies. One such technology, namely polymeric materials, is available for coating onto steel or galvanized steel. Physical and chemical aging is an important factor that affects the properties of polymer and, therefore, of coatings. The present study is focused on the effect of aging on the adhesive performance and rheological property of new eco-friendly anticorrosion organic coating film that we are developing, which has a low volatile organic compound (VOC) content of less than 10%. Exposure to accelerated thermal cycling certainly had an influence on the coating film in that it degraded its adhesive strength and affected the storage modulus and loss tangent. E′ and tan δ were found to evaluate likely planes of failure in multilayer combinations of film. During aging at room temperature, the solvent might evaporate and reach equilibrium. A significant phenomenon was observed, namely that the strengthening effect might relate to the application of tensile stress before the complete evaporation of the solvent. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

The article discusses an approach to uniform outlet flow of molten polymer for a complex die profile. It examines the impact of the length of die lands on flow balancing of a commercial product die with a cross flow. A simulation of the approach designed to gather data to complete a formulated objective function is presented. The authors concluded that higher ratio of the land length to the height of the zone with cross flow are directly from the extruder.