Commercial Polycarbonate Research Articles

Lithography-free study of spin torque

We developed a non-lithographic technique to contact sub-100 nm nanowires for spin transfer torque experiments. Co/Cu multilayers were grown by electrodeposition in nanoporous commercial polycarbonate membranes from a Co/Cu bath. A home-made sample holder allows bottom and top electrical contacts to be made to individual nanowires in the CPP geometry. Experimental evidence of the spin transfer torque effect is given for (Co/Cu) n multilayers by recording d V/d I spectra as a function of the DC current amplitude.

Electrodeposition of nanocrystalline silver films and nanowires from the ionic liquid 1-ethyl-3-methylimidazolium trifluoromethylsulfonate

We report in this paper on the electrodeposition of nanocrystalline silver films and nanowires in the air and water stable ionic liquid 1-ethyl-3-methylimidazolium trifluoromethylsulfonate [EMIm]TfO containing Ag(TfO) as a source of silver. The study was performed by means of cyclic voltammetry and chronoamperometry, and the electrodeposits were characterized by SEM-EDX and XRD. The cyclic voltammetry behaviour showed typical reduction and oxidation peaks corresponding to the deposition and stripping of silver in the employed electrolyte. XRD patterns of the electrodeposited silver layers revealed the characteristic peaks of crystalline silver with crystallites in the nanosize regime. Silver nanowires with average diameters and lengths of about 200 nm and 3 μm, respectively, were prepared by potentiostatic deposition within a commercial nuclear track-etched polycarbonate template.

The relative placement of linear viscoelastic functions in amorphous glassy polymers

A procedure is described and analyzed for the determination of the relative placement of linear viscoelastic functions and their relative relaxation∕retardation spectra for a commercial polycarbonate (LEXAN GE). The complete set of viscoelastic functions in creep and relaxation was obtained from two simple experimental data, namely the linear viscoelastic response in shear and the pressure volume temperature (PVT) behavior. The dimensionless bulk compliance was extracted from PVT data showing that it coincides with the memory function appearing in the Kovacs, Aklonis, Hutchinson, Ramos phenomenological theory [Kovacs, A. J., J. J. Aklonis, J. M. Hutchinson, and A. R. Ramos, J. Polym. Sci., Polym. Phys. Ed. 17, 1097 (1979)]. Our results are compared with the relevant literature data obtained on different polymers and show that polycarbonate fulfills simultaneously the responses features concerning the relative placement of the bulk and shear moduli [Kono, R. J., Phys. Soc. Jpn. 15, 4 (1960)], the shapes of...

A methodology to assess the rate and pressure sensitivity of polymers over a wide range of strain rates

This paper details a methodology to test the mechanical response of soft, pressure sensitive materials, over a wide range of strain rates. A hybrid experimental–numerical procedure is used to assess the constitutive parameters. The experimental phase involves axial compression of a cylindrical specimen which is confined by a tightly-fit sleeve that is allowed to yield plastically, thus applying a constant confining pressure. The usually neglected frictional effects between the specimen and the sleeve are fully accounted for and characterized in detail. With commercial polycarbonate as a typical example, it is shown that pressure sensitivity and rate sensitivity are not coupled, thus reducing the number of tests needed to characterize a material. The results of numerical simulations indicate that the pressure sensitivity index (angle β in the Drucker-Prager material model) has little influence on the hydrostatic and confining pressures, whereas the equivalent stress sustained by the specimen increases with β, which for commercial polycarbonate is found to be β=15°.

Photoviscoelastic behavior and residual thermal birefringence in optical-grade polycarbonates

The stress-optical coefficient functions of two optical-grade polycarbonates (PCs) have been obtained by simultaneous measurements of the relaxation modulus and strain-optical coefficient functions. Nonlinear behavior of the relaxation modulus and strain-optical coefficient was observed at small strains at room temperature. Comparison of these functions in the linear region with those of a commercial grade PC was made. These functions have been incorporated to linear viscoelastic and photoviscoelastic constitutive equations to calculate residual thermal birefringence in freely quenched PC plates. The numerical results have been compared with the measurements indicating a fair agreement between them.

ESC resistance of commercial grade polycarbonates during exposure to butter and related chemicals

Three commercial grades of polycarbonates (Lexan ® 144, Lexan ® 104 and Makrolon Rx1805) were studied with respect to resistance to environmental stress cracking (ESC) when exposed to butter and related chemicals. The polycarbonates (PCs) were extensively characterised to determine whether differences in ESC resistance could be related to their structural or chemical properties. MALDI-TOF mass spectrometry revealed that Makrolon Rx1805 contains a low molar mass material characterised as poly(propylene glycol)p, which was confirmed by ATR-FTIR and 1H NMR. Some “non-absorbing” chemicals, such as butter, cause the PCs to be less resistant to ESC under stress. The reason for this is that these chemicals and the PCs have sufficiently similar Hansen solubility parameters to allow surface conformational changes even though absorption is non-existent or extremely small. ATR-FTIR was used to detect changes in molecular structure in the PC surfaces.

The Possibility of Glass Storage Device with Long Term Preservation and High Density Adopted Nd:YAG Laser

The purpose of this study is doing analogical inference of characteristic of glass by using the critical disconnect bonding and verifies this equation is proper or not to predict the property of matter when a laser is induced to glass substrate. As starting composition, 10Na2O-10CaO-xB2O3-(70-x)SiO2 glasses (x= 10 ~ 25) were used and Nd:YAG laser(532nm) was applied to make a microstructure onto surface. Followed to the portion of B2O3 is increasing the bonding strength was increased. As the result bump size was decreased at the same laser fluence. The minimum size of the bump was about 1.3μm at 328J/cm2 laser fluence. This size is similar pitch size compared with commercial polycarbonate CD.

Modeling of Nonlinear Viscoelastic Creep of Polycarbonate

AbstractThe creep behavior of a commercial grade polycarbonate was investigated in this study. 10 different constant stresses ranging from 8 MPa to 50 MPa were applied to the specimen, and the resultant creep strains were measured at room temperature. It was found that the creep could be modeled linearly below 15 MPa, and nonlinearly above 15 MPa. Different nonlinear viscoelastic models have been briefly reviewed and used to fit the test data. It is shown that the Findley model is a special case of the Schapery model, and both the Findley model and the simplified multiple integral representation are suitable for properly describing the creep behavior of the polycarbonate investigated in this paper; however, the Findley model fit the data better than the simplified multiple integral with three terms.

Simultaneous Transient Temperature Sensing of Impacted Polymers Using Infrared Detectors and Thermocouples

Infrared detectors are probably the most popular device used for transient temperature monitoring of materials deformed in the high strain-rate regime. Embedded thermocouples have also been shown to be suitable for that purpose, especially with poor thermal conductors such as polymers [Rittel, Exp Mech 38(2), 73–79, 1998b]. However, there is no direct comparison between these two techniques. This paper presents experiments during which commercial polycarbonate specimens were deformed dynamically, while the surface and core temperatures were monitored using an infrared detector and embedded thermocouple respectively. An excellent agreement was obtained between the two techniques, confirming the suitability of thermocouples for transient temperature sensing.

Suzuki Polycondensation Put to Work: A Tough Poly(meta‐phenylene) with a High Glass‐Transition Temperature

Challenging commercial polycarbonate: Suzuki polycondensation afforded a high-molar-mass poly(meta-phenylene) (see structure) which displays not only outstanding toughness, convenient processability, and a high glass-transition temperature, but also considerable resistance against environmental stress-cracking; thus, it rivals high-performance polycarbonate in its fundamental properties.

Fast neutron dose response of a commercial polycarbonate

A commercial polycarbonate produced in Brazil is being studied to be used as neutron detector material using Solid State Nuclear Track Detection (SSNTD) method replacing the well-known detector materials Makrofol and CR-39. This technique is based on the damage (tracks) registration of charged particles produced by the interaction of neutrons with carbon and oxygen atoms of some dielectric materials. The IPEN dosimeter prototype is composed by 30 × 10 × 1.5 mm 3 polycarbonate piece inserted between two Polymethyl Methacralate (PMMA) plates 2 mm thick. The prototypes were irradiated placed on an ISO slab phantom using an isotropic 241AmBe source at LN/LNMRI (Neutrons Laboratory of the National Laboratory of Ionizing Radiation Metrology). To study the dose response groups of five prototypes were irradiated with Hp(10) from 0.5 to 20 mSv with normal incidence and to investigate the angular incidence effect with Hp(10) = 5 mSv with incidence angles of 15°, 45°, 60°, 75°, 85° and 90°. The detectors were revealed by chemical etching with the solution PEW-40 during 3 h. The track density of the detector surface was determined by the average of track counting of five fields ( 20 × 0.1 mm 2). The track response to equivalent dose Hp(10) showed a good agreement with linear fit in the studied interval. The track density strongly decreases for incidence angles higher than 45°.

Simple and rapid methods for the fabrication of polymeric and glass chips for using in analytical chemistry

This paper describes simple and rapid methods for the fabrication of glass and polymeric chips for routine analytical applications. The methods are easily interfaced to the general laboratory environment and do not require special clean room facilities or expensive instruments. Glass microchips were fabricated by etching with HF solution. Microfluidic channels were designed with CAD program and transferred onto a sheet of commercial polymeric self-adhesive (PSA) film by a cutter plotter. The PSA film was used as a mask for etching process. The etching rate was about 7 μm min −1. A cover glass plate was sealed on the top of etched substrate by using polycellulose (cellophane). Polymeric microchips were fabricated by sawing with a jigsaw. Commercial polycarbonate (PC) was used as a substrate and two iron sheets were used as leader masks. While this restricts us to the fabrication of straight channels, it is however, much faster and less complicated than the other methods. The chip comprised three polymeric plates and the channels were created in the middle plate. Thermal bonding was used to bond three layers of the microfluidic chip. With this method, we could achieve simple channels with the width of about 200 μm. The channel depth depends on the polymeric plate thickness. Fabricated channels were accurate without any sinuosity or sideshow.

Templated electrodeposition of silver nanowires in a nanoporous polycarbonate membrane from a nonaqueous ionic liquid electrolyte

Template electrodeposition has been used to prepare a wide range of nanostructures but has generally been restricted to aqueous electrolytes. We report the deposition of silver nanowires in a commercial nuclear track-etched polycarbonate template from the nonaqueous ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]) using silver electrochemically dissolved from the anode. Transmission electron microscopy (TEM) shows that the nanowires have a very high aspect ratio with an average diameter of 80 nm and length of 5 μm. Ionic liquid electrolytes should greatly extend the range of metals that can be electrodeposited as nanowires using templates.

Alicyclic Polyimides based on bicyclo[2.2.1]heptane- 2,3,5,6-tetracarboxylic 2,3-5,6-dianhydrides

The alicyclic polyimides were prepared by reacting bicyclo[2.2.1]heptane-2,3,5,6-tetracarboxylic-2,3-5,6-dianhydride (BHDA) with aliphatic or aromatic diamines in hexamethylphosphoramide. The poly(amic acid)s possessed inherent viscosities (νinh)in the range from 0.13 to 0.38, and they formed free-standing and flexible films after being cast then cured. The fully alicyclic polyimide films exhibited a cutoff around 230 nm, and are transparent even in the near infrared region. The optically estimated ε of the fully alicyclic polyimides was about 2.6. All the alicyclic polyimide possessed negligibly small birefringence below 10-4. Semi-aromatic polyimide PI(BHDA + 1,3-BAB) had good thermal stability with no significant weight loss up to 350°C, and the T5 was around 450°C, although the Tg was as low as 197°C. All polyimides exhibited broad dispersive peaks of diffraction around 16° (2τ). The PI(BHDA + BBH) film possessed a tensile modulus of 2.05 GPa and a tensile strength of 52 MPa, and these values can compete in terms of strength with those of a commercial polycarbonate.

Fast Mass Transport Through Sub-2-Nanometer Carbon Nanotubes

We report gas and water flow measurements through microfabricated membranes in which aligned carbon nanotubes with diameters of less than 2 nanometers serve as pores. The measured gas flow exceeds predictions of the Knudsen diffusion model by more than an order of magnitude. The measured water flow exceeds values calculated from continuum hydrodynamics models by more than three orders of magnitude and is comparable to flow rates extrapolated from molecular dynamics simulations. The gas and water permeabilities of these nanotube-based membranes are several orders of magnitude higher than those of commercial polycarbonate membranes, despite having pore sizes an order of magnitude smaller. These membranes enable fundamental studies of mass transport in confined environments, as well as more energy-efficient nanoscale filtration.

Hysteretic thermal behavior of amorphous semi-aromatic polyamides

The hysteretic thermal behavior of two amorphous semi-aromatic polyamides, subjected to cyclic loading at high stress levels, has been investigated. The two polymers, called 1I and 1.8T, were selected with regards to chain mobility and plastic deformability considerations. This work reports the exothermal response of these materials to high level cyclic stress (of the order of σ y), with emphasis on the initial thermal peak, normally observed in commercial polycarbonate (PC) and not in commercial polymethylmethacrylate (PMMA). The investigated materials exhibit noticeable initial thermal peaks, which are similar, to some extent, to those observed in PC. The present results suggest that chain mobility may indeed be partially responsible for the initial exothermal peak, thus supporting the hypothesis that it may be related to the transition from shear deformation zones to chain disentanglement crazing.

Chemical recycling of polycarbonate in a semi-continuous lab-plant. A green route with methanol and methanol–water mixtures

Alkali-catalysed depolymerization of polycarbonate (PC) wastes by alcoholysis in supercritical or near critical conditions has been studied in order to recover the essential monomer bisphenol A (BPA) and dimethyl carbonate (DMC) as a valuable by-product. This work aims to study the continuous process and possible scale-up for decomposition of both commercial PC and PC plastic wastes using methanol as solvent/reagent and NaOH as alkali catalyst. Total depolymerization of PC has been achieved working at a temperature range of 75–180 °C and pressures from 2 to 25 MPa. The influence of operation conditions on product yield, selectivity and reaction rate has been studied, including temperature, pressure, methanol/cosolvent ratio and catalyst concentration. BPA yields of 80–90% (kg product/kg PC) were achieved with a further crystallization and separation of the final product, resulting in BPA pure crystals (99.9%). DMC yield reached 35% (kg DMC/kg PC) and was proved to be strongly dependent on pressure and methanol/H2O ratio. Non desired by-product yield was negligible when pure methanol was used as solvent and selectivity decreased with increasing methanol/H2O ratio.

Formation of TiO2 and ZrO2 Nanotubes Using Atomic Layer Deposition with Ultraprecise Control of the Wall Thickness

Nanotubes of TiO2 and ZrO2 (see Figure) with diameters of ca. 30–200 nm have been successfully fabricated by atomic layer deposition in a one-step process utilizing nanoporous membranes (commercial polycarbonate filters) as templates. Sub-angstrom wall thickness control and high aspect ratios can be achieved by this method.

Palladium membranes prepared by r.f. magnetron sputtering for hydrogen purification

Pd thin films, 5-μm thick, were deposited by r.f. magnetron sputtering on porous stainless steel discs (0.5 μm rejection grade) as membrane for hydrogen filtering. In order to fill the steel pores and prepare a flat surface for the Pd coating, a polymeric layer made of commercial polycarbonate was deposited on the steel surface by spin coating technique. The PC layer shows a relatively smooth surface morphology and strong adhesion to the porous substrate. Secondary electron microscopy analysis of the fractured sample shows, in fact, branches of polymeric material which depart from the PC surface and enter in the substrate pores for length ∼10 μm ensuring the necessary anchorage. Palladium sputter deposition produced rough and pinholes free Pd coating well adherent to the PC buffer layer. Gas selectivity tests by permeation analysis evidenced an hydrogen permeance of 5×10 −1 μmol m −2 s −1 Pa −1 of the as-prepared Pd–PC composite membrane and high H 2 to N 2 selectivity.

Determination of potential migrants in polycarbonate containers used for microwave ovens by high-performance liquid chromatography with ultraviolet and fluorescence detection.

The determination of several compounds present in a commercial polycarbonate container intended to be used in microwave ovens which could be considered as potential migrants has been carried out by reversed-phase high-performance liquid chromatography (HPLC) with both ultraviolet (UV) and fluorescence detectors. Total dissolution with dichloromethane and polymer reprecipitation with methanol have been used to evaluate 100% potential migration as the worst case. The extract consisted of a complex mixture containing monomers, oligomers, UV stabilizers, antioxidants, degradation products, and other additives. Phenol, Bisphenol A, 2,4-di-tert-butylphenol, Cyasorb UV5411, bis(2-ethylhexylphthalate), Irganox 1076, and Irgafos 168 were identified by both retention times and fluorescence-to-UV ratios. Additional confirmation was achieved by HPLC with diode array detection and gas chromatography-mass spectrometry. Recovery percentages were in the range of 73.8-94.4%, the lowest one being for the antioxidant Irgafos 168 due to its transformation into the phosphate form and 2,4-di-tert-butylphenol. The concentrations of the studied analytes present in the polycarbonate container ranged between 0.9 and 240 microg.g(-)(1). The total dissolution conditions that may affect the final concentration of analytes, mainly Bisphenol A, are discussed.