Society Of Plastics Engineers Research Articles

Electron transport properties of polyaniline composite films containing poly(3-hydroxybutyric acid)

Polyaniline (PANI) composites containing poly(3-hydroxybutyric acid) (PHB) were synthesized via in situ deposition technique. The oxidative polymerization of aniline hydrochloride was carried out by dissolving different weight percentages (10 wt%, 20 wt%, 30 wt%, 40 wt%, and 50 wt%) of PHB using ammonium persulfate as an oxidant. The as-synthesized composites were characterized using Fourier-transform infrared spectroscopy and X-ray diffraction pattern. The surface morphology of the resulting composites was studied using transmission electron microscopy. The temperature-dependent direct current conductivity of the synthesized composite films was measured, and the activation energy responsible for the conductivity was examined. Incorporation of the biodegradable polymer, PHB, during the preparation of new PANI composites significantly increased the conductivity of the resulting composites. POLYM. COMPOS., 34:1655–1662, 2013. © 2013 Society of Plastics Engineers

Preparation and properties of polyhedral oligomeric silsesquioxane/epoxy hybrid resins

Octaaminophenyl polyhedral oligomeric silsesquioxane (OAPS) was synthesized using three-step method and used to modify o-cresol-novolac epoxy resin (ECN) for printed circuit board. The influence of OAPS on the reactivity and the final properties of the hybrid networks were evaluated. The intercrosslinking reaction between ECN and OAPS was confirmed by Fourier transform infrared spectra. The ECN/OAPS hybrids have better impact strength, higher electrical resistivity and thermal stability, lower water absorption than the unmodified ECN. The volume resistivity and surface resistivity of the hybrids increase by an order of magnitude or more compared to the neat epoxy. The thermal stability of the hybrids improves by the incorporation of OAPS; the initial decomposition temperature and char yield show an increasing tendency up to 4 wt% loading of OAPS. The hybrids exhibit higher storage modulus and glass transition temperature (Tg) than the neat epoxy. The Tg of the hybrids greatly improves up to 153.3°C at 3 wt% content, much higher than 119.4°C of the neat epoxy. POLYM. COMPOS., 34:1753–1760, 2013. © 2013 Society of Plastics Engineers

Effect of in situ bonding system and surface modification of montmorillonite on the properties of butyl rubber/montmorillonite composites

Isobutylene–isoprene rubber (IIR)/nanoclay composites were prepared by solution intercalation method. Cloisite Na+ montmorillonite and organo‐modified montmorillonite (OMMT) nanoclays, namely, cloisite 10 A, cloisite 15 A, and cloisite 20 A were used in this study. The effect of in situ bonding system HRH (hexametylene tetramine: resorcinol: hydrated silica) on the dispersion of used nanoclays in the rubber matrix were examined by X‐ray diffraction and scanning electron microscope (SEM). Both techniques showed complete exfoliation of the clays silicate layers in IIR/OMMT/HRH nanocomposites (NCs). Rheometeric and mechanical properties (tensile strength, elongation at break%, and E‐modulus) of the NCs were studied. The addition of HRH system to IIR/OMMT NCs improves their mechanical properties. Moreover, IIR/clays/HRH NCs showed a decrease in the scorch time (tS2) and the cure time (tC90), which is an industrial privilege for saving time and energy. Swelling measurements were used to determine the filler–rubber interaction (Qf/Qg), the molar mass between cross‐links (Mc) and the cross‐linking density (ν) for each composite. The presence of HRH system enhances the rubber–filler interaction; in addition to an increase in the cross‐link density values. POLYM. COMPOS., 34:1559–1565, 2013. © 2013 Society of Plastics Engineers

Online monitoring of diallyldimethylammonium chloride polymerization

Diallyldimethylammonium chloride, which is an acidic salt with numerous applications, was polymerized in water at three different monomer concentrations and at three different pHs which the monomer is in charged form. Reactions were investigated by the automatic continuous online monitoring of polymerization technique. Conversion, molecular weight, and reduced viscosity were monitored. The reaction is found to be second-order with respect to monomer. Rate constants and molecular weights tend to increase with pH and concentration. POLYM. ENG. SCI., 54:1350–1356, 2014. © 2013 Society of Plastics Engineers

Morphological factors affecting the permeation resistance of nanocomposite blend films

The micro- and nanoscale morphologies of thin nanocomposite films comprising an immiscible nylon 6/polyethylene blend reinforced with modified sodium montmorillonite were found to substantially affect water vapor transmission rates (WVTRs). Maleic anhydride-grafted high-density polyethylene was incorporated as a compatibilizer between the nylon and polyethylene phases. Preferential incorporation of an organosilicate nanoclay in the nylon phase had a secondary effect on the overall blend morphology and thermal properties. Different degrees of phase continuity in the nanocomposite blend system were studied for their effect on WVTRs by varying the relative viscosities of the polymer phases. Transmission electron and atomic force microscopy were utilized to reveal the morphologies of the nanocomposite blends. POLYM. ENG. SCI., 54:1341–1349, 2014. © 2013 Society of Plastics Engineers

In Situ synthesis of poly(styrene-butylacrylate-acrylic acid) latex/barium sulfate nanocomposite and evaluation of their film properties

Barium sulfate nanocrystals of average 40 nm sizes were prepared by the micellar solution spray process. The influences of atomized impingement flow on nanoparticle formation and stabilization were inspected on the basis of Fourier transform infrared (FTIR), X-ray diffraction, and transmission electron microscopy analysis. Poly(styrene–butylacrylate–acrylic acid) (PSBA) nanocomposites were synthesized by in situ copolymerization in the presence of 0.5–2.5% BaSO4 nanoparticles. FTIR and atomic force microscopy analysis confirmed the uniform dispersion of 2% or less nano-BaSO4 within the PSBA matrix. The strength of interfacial adhesion between the nanoparticle and copolymer was examined on the basis of hydroscopicity, differential scanning calorimetry, thermogravimetric analysis, and universal testing machine analysis of nanocomposite film. The glass transition and thermal decomposition temperatures of PSBA latex were shifted toward higher temperatures by the restriction of nano-BaSO4 on its segmental and long-range chain mobility. The well-dispersed nano-BaSO4, with a larger fraction of immobilized copolymer on the pigment surface, improves the scratch and abrasion resistance, decreases the water uptake, and increases the tensile strength and elongation at break of the latex film within the specific loading. Thus, fabricating the PSBA/BaSO4 nanocomposite presents an effective approach for development of latex coatings with enhanced performance. POLYM. COMPOS., 34:1670–1681, 2013. © 2013 Society of Plastics Engineers

Characteristics of the surface modification of montmorillonite with a bifunctional block copolymer

A bifunctional polystyrenic block copolymer with 4vinyl pyridine (4VP) units in one block and pendant methacrylate units in the other block (MMSP) was prepared and employed as a surface modifier for montmorillonite (MMT). The interaction of the 4VP units with the surface of MMT layers was examined by using spectroscopic methods. X-ray diffraction spectroscopy data exhibited an increase in the interlayer spacing (D value) of MMSP-MMT with an increased amount of MMSP, confirming the high reactivity of 4VP units and the effective intercalation of MMSP to MMT (MMSPMMT). In a Fourier transform infrared spectroscopy study, linear shifting and a narrower band width of the SiAOASi stretching vibration with increased MMSP content indicated effective intercalation and surface modification processes. With an increased amount of MMSP, the relative amount of free pyridyl units to pyridinium units increased, indicating plausible saturation of the MMT surface at high MMSP content. POLYM. COMPOS., 34:1640–1647, 2013. V C 2013 Society of Plastics Engineers

Constant-temperature embossing of supercooled polymer films

In conventional hot embossing, a thermoplastic polymer undergoes phase transitions in liquid, semi-solid, and solid states through cyclic heating and cooling. This paper, in contrast, describes the development of a constant-temperature embossing process and compares its characteristics against standard hot embossing. The new process utilizes the crystallizing nature of supercooled polymer films to obtain the necessary phase transitions. By softening and crystallizing the supercooled polymer at the same temperature, the embossing and solidification stages can be carried out isothermally without a cooling step. PET, due to its relatively slow crystallizing kinetics, was chosen as a model material for this study. The embossed films with microgroove patterns of different sizes and aspect ratios were characterized for their replication fidelity and accuracy. For supercooled PET films, constant-temperature embossing with high replication quality and acceptable demolding characteristics was achieved in a large processing temperature window between Tg and Tm of PET. A parametric process study involving changes of the embossing temperature and embossing time was conducted, and the results indicated that the optimal process parameters for constant-temperature embossing can be derived from the crystallization kinetics of the polymer. The removal of thermal cycling is a major advantage of constant-temperature embossing over conventional hot embossing and represents an important process characteristic desired in industrial production. POLYM. ENG. SCI., 54:1100–1112, 2014. © 2013 Society of Plastics Engineers

Observation and understanding of the tear mechanism of polyethylene blown films at variable loading angles

Tear is a key physical property of polyethylene (PE) blown films. There are many variables that affect the overall tear property, such as tear path and plastic deformation wake. In this study, five blown PE films are prepared and tested by the Elmendorf tear test at five sampling angles, i.e. 0 (MD), 30, 45, 60, and 90 (CD) degrees. Statistical analysis is carried out on the tear values and the variation of the tear data is investigated based on the observation of the tear samples. The mechanism of severely curved crack, i.e. J-tear, is also studied to understand the tear property variation of blown PE films. In addition, the relationship between tear values and tensile toughness in perpendicular direction is investigated to understand the role of a process zone lying in front of a crack tip during tear. POLYM. ENG. SCI., 54:1038–1046, 2014. © 2013 Society of Plastics Engineers

Modeling the rheology of SR1500 and LY556 epoxies under manufacturer's recommended cure cycles after viscosimetry and rheometry characterization

The evolution of the viscosity of two commercial epoxy resin systems subjected to manufacturer's recommended cure cycles was studied in detail. The two systems were characterized through rotational viscosimetry and oscillatory rheometry. It was observed that the different size of the samples in the two setups influenced the kinetics and, thus, the evolution of the cure and viscosity. The differences resided in the effective temperature experienced by the resin at each moment. Original rheological constitutive relations are proposed for each resin system and mass quantity, aiming to capture the “real” processing conditions. All the experimental and modeling procedures are described in detail and the new rheological constitutive relations are presented. POLYM. ENG. SCI., 54:831–839, 2014. © 2013 Society of Plastics Engineers

An evaluation of the pressure-dependent melt viscosity of polyphenylsulfone

A method for the determination of pressure-affected viscosity from capillary rheometry and pressure–volume–temperature (PVT) data was tested on polyphenylsulfone melt. Shear viscosity data evaluated at selected temperatures (345–375°C) were interlinked to the PVT data at pressures ranging from 1 to 200 MPa. According to the recently proposed correlation approach, a pressure-dependent shear viscosity is derived from the relationship (verified on several commodity polymers) between temperature-dependent viscosity and a free volume parameter computed using the Simha–Somcynsky equation of state. Finally, the predicted pressure-viscosity coefficient was compared with the value obtained experimentally on a modified single piston rheometer. POLYM. ENG. SCI., 54:711–715, 2014. © 2013 Society of Plastics Engineers

Thermal decomposition behavior of oligo(4-hydroxyquinoline)

In this study, the kinetic parameters and reaction mechanism of decomposition process of oligo(4-hydroxyquinoline) synthesized by oxidative polymerization were investigated by thermogravimetric analysis (TGA) at different heating rates. TGA-derivative thermogravimetric analysis curves showed that the thermal decomposition occurred in two stages. The methods based on multiple heating rates such as Kissinger, Kim–Park, Tang, Flynn–Wall–Ozawa method (FWO), Friedman, and Kissinger–Akahira–Sunose (KAS) were used to calculate the kinetic parameters related to each decomposition stage of oligo(4-hydroxyquinoline). The activation energies obtained by Kissinger, Kim–Park, Tang, KAS, FWO, and Friedman methods were found to be 153.80, 153.89, 153.06, 152.62, 151.25, and 157.14 kJ mol−1 for the dehydration stage, 124.7, 124.71, 126.14, 123.75, 126.19, and 124.05 kJ mol−1 for the thermal decomposition stage, respectively, in the conversion range studied. The decomposition mechanism and pre-exponential factor of each decomposition stage were also determined using Coats–Redfern, van Krevelen, Horowitz–Metzger methods, and master plots. The analysis of the master plots and methods based on single heating rate showed that the mechanisms of dehydration and decomposition stage of oligo(4-hydroxyquinoline) were best described by kinetic equations of An mechanism (nucleation and growth, n = 1) and Dn mechanism (dimensional diffusion, n = 6), respectively. POLYM. ENG. SCI., 54:992–1002, 2014. © 2013 Society of Plastics Engineers

Rheological characterization of polymers fiber composite

The use of reinforced polymer composites has continued to show substantial growth due to desirable cost and performance characteristics, especially related to mechanical properties. Wollastonite and glass fibers are materials that can be used to improve polymer performance. Its vast array of applications suggests potential usage in various fields of work (e.g., plastics, friction materials paintings, coating, and construction products), but there is not much data available in the literature related to rheological properties of fiber reinforced polymers. In this work, a study of shear and extensional properties of composite materials containing wollastonite and glass fibers is performed using rotational and extensional rheometry. Suspensions containing different concentrations of wollastonite and glass fibers, in Newtonian and viscoelastic matrices are investigated. Results are obtained for different concentrations and temperatures. It is observed that even the addition of low fiber concentration can affect both shear and elongational properties, leading to different final products characteristics. POLYM. COMPOS. 34:1269–1278, 2013. © 2013 Society of Plastics Engineers

Precipitation polymerization of PLGA with Sn(Oct)2 /BuOH in supercritical carbon dioxide

In order to increase molecular weight of PLGA, BuOH was introduced as a co-initiator to Sn(Oct)2 in ring-opening precipitation polymerization of L-lactide and glycolide in supercritical carbon dioxide (ScCO2). The polymerization mechanism of the reaction processes on Sn(Oct)2 with BuOH was explored. The positive effect of BuOH on polymer molecular weight was studied. PLGA with higher Mw (of 19,500 g/mol) and narrower PDI (of 1.12) was successfully prepared by ring-opening precipitation polymerization in ScCO2 using Sn(Oct)2/BuOH as an efficient catalytic system. Influence of reaction conditions, such as monomer feed concentration, reaction temperature, pressure, and time, were also investigated in detail. POLYM. ENG. SCI., 54:704–710, 2014. © 2013 Society of Plastics Engineers

Effect of reynolds number on the dispersion of carbon black in natural rubber latex and filler-rubber interfacial interaction in high-speed jet flow field

A novel strategy of high-speed impinging jet processing technique was developed to prepare rubber composites by directly mixing natural rubber latex (NRL) with carbon black (CB). The results showed that CB could be more evenly dispersed into natural rubber by jet compounding technique, compared with the traditional dry process. The dispersion of carbon black was improved at higher Reynolds number because of more intensive shear force. Furthermore, a high performance of natural rubber latex/CB composite was gained by jet compounding technique. When compared to the traditional dry process, the mechanical properties and abrasion resistance of the composite prepared by the jet compounding technique were greatly improved because of the improved filler–rubber interaction at higher Reynolds number. POLYM. COMPOS., 34:1071–1075, 2013. © 2013 Society of Plastics Engineers

Preparation and properties of nitrile rubber/superfine down powder composites

The purpose of this study was to improve utilization rate of waste protein materials. In this article, down fiber was ground into superfine down powder (SDP) and then filled into nitrile rubber (NBR) directly. The cure-curve, dynamic rheological behavior, morphology, tensile property, and thermal properties of NBR/SDP composites were studied. The results showed that SDP formed a developed but weak filler–filler network, which resulted in obvious “Payne effect,” the increased storage modulus, loss tangent and complex viscosity of the NBR/SDP composites. SDP could be distributed uniformity in the NBR matrix, but the large sizes of most SDP weaken the interaction between the particles and NBR matrix. The tensile property was improved by high SDP load. The SDP decreased the temperature at 5% weight loss of the NBR/SDP composites, but not apparently affected the maximum weight loss rate of the NBR. At last, the results of this study suggested that SDP was potential to be one of the available additives fillers in rubber industry, as long as the smaller size of SDP was achieved. POLYM. COMPOS., 34:1136–1143, 2013. © 2013 Society of Plastics Engineers

Zein nanofibrous membranes as templates for biomineralization of hydroxyapatite crystallites

Bio-inspired approaches for mimicking the mineralization process of hydroxyapatite (HAp) with highly regulated structures have been intensively developed using biomacromolecular templates. In the present study, zein, a hydrophobic natural protein, was explored to induce the biomineralization of HAp nanocrystallites on the unique nanofibrous structures generated by electrospinning. Zein electrospun fibers with diameters range from several hundred nanometers down to 100 nm were obtained using formic acid as solvent. Randomly oriented apatite crystals were observed on zein nanofibrous membranes after several incubating cycles. The nature of the deposited mineral phase was confirmed as HAp crystallites by energy-dispersive spectroscopy, Fourier transform infrared spectroscopy, and wide-angle X-ray diffraction. A preliminary study of in vitro cytotoxicity and osteoblast adhesion revealed that mineralized zein nanofibrous membranes did not induce cytotoxic effects and had a positive effect on osteoblast growth. Zein/HAp membranes possessed the unique nanofibrous structural features and coating of HAp nanocrystallites may have a wide variety of potential applications for bone repair and regeneration. POLYM. COMPOS., 34:1163–1171, 2013. © 2013 Society of Plastics Engineers

Preparation of Cu/Dickite/LLDPE nanocomposites and synergistic effect of exfoliated dickite and nano-Cu in LLDPE matrix

A novel anticorrosion packaging nanocomposite composed of LLDPE (linear low-density polyethylene), nano-sized Cu, and exfoliated dickite was prepared via melt mixing combined with melt extruding process. X-ray diffraction and transmission electron microscopy (TEM) were employed to characterize the resultant nanocomposite. The results showed that most dickite layers were exfoliated and the nano-Cu particles were distributed uniformly in the polymer matrix. The characteristic properties of the Cu/dickite/LLDPE nanocomposite were investigated using salt spray test, thermogravimetry analysis, mechanical test, and antibacterial test. The salt spray test results showed that exfoliated dickite and nano-Cu improved the anticorrosion properties of the Cu/dickite/LLDPE nanocomposite in simulated ocean environment, respectively. Furthermore, the coexistence of exfoliated dickite and nano-Cu in Cu/dickite/LLDPE nanocomposite produced a synergistic effect on enhancing the anticorrosion properties. Additionally, the co-incorporation of exfoliated dickite and nano-Cu in LLDPE matrix also improved the thermal-oxidative stability and mechanical properties of the polymer matrix. The bactericidal properties evaluation showed that the Cu/dickite/LLDPE nanocomposite had better bactericidal ability because of the presence of nano-Cu in LLDPE matrix. POLYM. COMPOS., 34:1061–1070, 2013. © 2013 Society of Plastics Engineers

Structural, optical, and electrical characterization of the poly[9,9-dioctylfluorenyl-2,7-diyl]-co-1,4-benzo-(2,1,3)-thiadiazole thin film fabricated by electrostatic spray technique

The article presents the efficient fabrication of the Poly[9,9-dioctylfluorenyl-2,7-diyl]-co-1,4-benzo-(2,1,3)-thiadiazole (F8BT) thin film using the electrostatic spray technique. Electrostatic atomization of the in-house developed F8BT polymer ink was achieved at considerable low voltage. The structural and optical characterizations of the fabricated F8BT thin film were thoroughly investigated. Furthermore, the organic diode structure with electrostatic spray deposited F8BT thin film was fabricated and its performance was analyzed by performing current voltage measurement. The current–voltage characteristic curve of the organic diode showed nonlinear diode like behavior, thereby confirming the proper interference established between organic diode adjacent layers. The space charged limited current mechanism has been found to be dominant in the fabricated organic device with carrier mobility value of 5.65 e−4 cm2V−1s−1. POLYM. ENG. SCI., 54:675–681, 2014. © 2013 Society of Plastics Engineers

Optimizations of polyester degradation process of waste copper wire for the application of Cu recycling

Recycling of waste copper wire (WCW) has attracted much attention as waste has a huge negative impact on the natural environment. In this study, easy, low cost, and highly efficient technique for recycling copper materials from polymer-coated copper wire was developed using induction heating furnace. Polyester layer on the surface of WCW has been analyzed using FTIR (Fourier Transform Infrared) spectroscopy, Differential Scanning Calorimetry, and Dynamic Thermogravimetric Analysis. As a result, it was confirmed that the polymer coated on the Cu wire, was found to be indeed polyester. A voltage ranging from 562 to 969 V was applied to polymer-coated WCW using induction furnace to remove the coated polymer layer completely from the surface of WCW. FTIR and NMR (Nuclear magnetic resonance) spectroscopy analyses were performed to investigate degradation mechanism of polyester. After applying 969 V, FTIR spectra showed no significant peak for polyester indicating complete removal. Based on this FTIR and NMR analyses, authors assume that, unsaturated aliphatic hydrocarbons, polycyclic aromatic hydrocarbons, benzene, and ethylene are remained with Ash on the Cu wires as final products. Therefore, Cu recycling was successfully done by removing polyester completely at applied voltage of 969 V. POLYM. ENG. SCI., 54:607-615, 2014. (c) 2013 Society of Plastics Engineers