Polyethylene Thin Films Research Articles

VOC-Induced Flexing of Single and Multilayer Polyethylene Films As Gas Sensors.

The differential swelling and bending of multilayer polymeric films due to the dissimilar uptake of volatile organic compounds (VOCs; n-hexane, limonene) in the different layers was studied. Motions of thin polyethylene films triggered by the penetrant were investigated to learn more about how their deformation is related to VOC absorption. Single layers of metallocene or low-density polyethylene, and multilayers (2-288 layers) of these in alternating positions were considered. Single-, 24-, and 288-layer films displayed no motion when uniformly subjected to VOCs, but they could display simple curving modes when only one side of the film was wetted with a liquid VOC. Two-layer films displayed simple bending when uniformly subjected to VOCs due to the different swelling in the two layers, but when the VOC was applied to only one side of the film, more complex modes of motion as well as dynamic oscillations were observed (e.g., constant amplitude wagging at 2 Hz for ca. 50 s until all the VOC had evaporated). Diffusion modeling was used to study the transport behavior of VOCs inside the films and the different bending modes. Finally a prototype VOC sensor was developed, where the reproducible curving of the two-layer film was calibrated with n-hexane. The sensor is simple, cost-efficient, and nondestructive and requires no electricity.

Modification of the Surface Layers of Thin Multilayer Heat Shrink Polyethylene Films with Whiting-Filled Additive Vatpol 210 Pe

The article gives the results of investigating a surface-modifying composite for 50 μm thick multilayer heat shrink films. The main principles of optimisation of high-speed packaging lines working with thin multilayer heat shrink films are set out. The obtained characteristics of 50 μm thick multilayer heat shrink films with improved service properties are analysed.

Thermoviscoelastic models for polyethylene thin films

This paper presents a constitutive thermoviscoelastic model for thin films of linear low-density polyethylene subject to strains up to yielding. The model is based on the free volume theory of nonlinear thermoviscoelasticity, extended to orthotropic membranes. An ingredient of the present approach is that the experimentally inaccessible out-of-plane material properties are determined by fitting the model predictions to the measured nonlinear behavior of the film. Creep tests, uniaxial tension tests, and biaxial bubble tests are used to determine the material parameters. The model has been validated experimentally, against data obtained from uniaxial tension tests and biaxial cylindrical tests at a wide range of temperatures and strain rates spanning two orders of magnitude.

Recovery and utilization of graphite and polymer materials from spent lithium-ion batteries for synthesizing polymer–graphite nanocomposite thin films

The present study focuses on the synthesis of polyethylene (PE), polypropylene (PP) and graphite composite thin film (PE/GRx and PP/GRx) using recovered anode (graphite) and separator (polymers) materials of spent Lithium-ion batteries (LIBs). The synthesized PE/GRx and PP/GRx thin films are characterized by X-ray diffraction, Fourier transform infrared (FT-IR) spectroscopy, thermogravimetry and differential scanning calorimetric analysis. The mechanical and electrical properties of the synthesized PP/GRx and PE/GRx composite thin films have been evaluated. The results demonstrated ∼10 times increase in tensile strength in composite thin films (PP/GR20wt%; 33MPa; PE/GR20wt%; 38MPa) as compared to neat polymer thin film (PP and PE thin film: 3.4 and 3.0MPa). Similarly after graphite loading the specific conductance of composite films is increased 5–6 orders compared to the neat polymer thin film. The synthesis of polymer–graphite composite thin film using recovered materials of spent LIBs may effectively be used as an alternative for commercial graphite and polymer. The recovering of waste may decrease the quantity of the solid waste and reduce the potential pollution to the environment.

Laser Doppler Vibrometer Based Examination of the Efficiency of Introducing Artificial Delaminations into Composite Shells

Abstract During its operation, the laminate shell of the watercraft hull can be exposed to local stability losses caused by the appearance and development of delaminations. The sources of these delaminations are discontinuities, created both in the production process and as a result of bumps of foreign bodies into the hull in operation. In the environment of fatigue loads acting on the hull, the delaminations propagate and lead to the loss of load capacity of the hull structure. There is a need to improve diagnostic systems used in Structural Health Monitoring (SHM) of laminate hull elements to detect and monitor the development of the delaminations. Effective diagnostic systems used for delamination assessment base on expert systems. Along with other tools, the expert diagnostic advisory systems make use of the non-destructive examination method which consists in generating elastic waves in the hull shell structure and observing their changes by comparing the recorded signal with damage patterns collected in the expert system database. This system requires introducing certain patterns to its knowledge base, based on the results of experimental examinations performed on specimens with implemented artificial delaminations. The article presents the results of the examination oriented on assessing the delaminations artificially generated in the structure of glass- and carbon-epoxy laminates by introducing local non-adhesive layers with the aid of thin polyethylene film, teflon insert, or thin layer of polyvinyl alcohol. The efficiency of each method was assessed using laser vibrometry. The effect of the depth of delamination position in the laminate on the efficiency of the applied method is documented as well.

Melting behavior of thin polyethylene films

Melting behavior in thin films of linear low-density polyethylene (LLDPE) and high-density polyethylene (HDPE) was studied by local thermal analysis (µTA). Even in the films thinner than 100 nm, the melting temperature ( Tm) was successfully observed by µTA. For LLDPE, Tm decreased as the thickness became thinner than 150 nm. For HDPE, Tm increased with decreasing thickness. Polarized infrared spectroscopy revealed that an edge-on lamellar structure formed in both cases, meaning that the crystallite orientation may not be a reason why the thickness dependence of Tm was not the same for both resins. A possible explanation is that for LLDPE the segmental mobility in the amorphous region predominates with decreasing thickness, and for HDPE the chain orientation in the region predominates with decreasing thickness.

Effect of soil environment on the photo‐degradation of polyethylene films

ABSTRACTOutdoor weathering field trials performed with oxo‐degradable polyethylene (PE) thin films were conducted across temperate, grassland, and subtropical sites around Australia. It was found that a site factor, that was apparently independent of total solar dose and temperature, significantly impacted the rate and extent of photo‐oxidation. Controlled laboratory‐based accelerated aging trials of both PE film with no prodegradant and oxo‐degradable PE films (containing iron stearate) revealed that the rate and extent of PE photo‐oxidation did not correlate with temperature under the film or UV exposure, but was soil dependent. Under accelerated photo‐oxidative conditions, the time to reach embrittlement for a PE film aged over the soil from the temperate site (OM 8.4) was half (24.5 days) the time taken when aged over air (48 days). Further investigation revealed that humic acids and fulvic acids within soil organic matter may contribute to an increased rate of PE photo‐oxidation, possibly through the formation of volatile reactive oxygen species that may form under photo‐oxidative conditions. The presence of water also had a significant impact on the rate of photo‐oxidation. Overall, the impact of soil on PE photo‐oxidation was found to be complex and likely dependent at least in part on soil components that varied between different soil types, consequently influencing their photo‐chemistry. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42558.

Viscoplastic tearing of polyethylene thin film

Recent advances in noncontact strain measurement techniques and large-strain constitutive modeling of the linear low-density polyethylene film used in NASA superpressure balloons StratoFilm 420 are combined to provide a novel measurement technique for the tear propagation critical value of the J-integral. Previously these measurements required complex test configurations and procedures. It is found that the critical value of the J-integral increases by approximately 50 % when the strain rate is decreased from 1.33×10−4 s−1 to 1.33×10−5 s−1. It is shown that there is good correlation between measurements made on uniaxially loaded dogbone samples and circular diaphragms loaded by pressure, both with a 2-mm-wide slit in the middle. This result indicates that more extensive studies of strain-rate dependence may be made with the simpler, uniaxial test configuration.

Crystalline Si photovoltaic modules functionalized by a thin polyethylene film against potential and damp-heat-induced degradation

I–V curves for multicrystalline Si photovoltaic modules after the test of potential-induced degradation (PID).

Metallurgical By-Product Transformation and Its Plasma Modification to Increase HDPE Thermal Conductivity

ABSTRACTA metallurgical by product mostly constituted of Wustita (FeO) was transformed to Magnetite (Fe3O4) spheres using a flame treatment. Then magnetite spheres surface was modified by cold plasma treatment with ethylene, where a thin polyethylene film was deposited on the spheres surface. Finally, HDPE composites with modified spheres were obtained by melt mixing and its thermal conductivity was determined by MDSC. It was found that spheres surface modification helps to increase composites thermal conductivity.

Synthesis and Light-Induced Surface Potential Observation of Retinal Prosthesis Using Polyethylene Thin Films Immobilized with Photoelectric Dyes

Synthesis and Light-Induced Surface Potential Observation of Retinal Prosthesis Using Polyethylene Thin Films Immobilized with Photoelectric Dyes

Reprint of “An evaluation of thermal lags of fast-scan microchip DSC with polymer film samples”

A quantitative evaluation has been tried on the thermal lags of a fast-scan (≤104Ks−1) microchip differential scanning nanocalorimeter (DSC). A thin layer (∼0.2μm thick) of a standard material of Tin was vapor deposited on a thin film of polyethylene (PE) sample (∼1–10μm thick), and the thermal lags have been examined by the dependences on the applied heating rate, film mass, and film thickness of the melting onset temperature of Tin on the bottom and top surfaces of PE films put on the sensor stage of nanocalorimeter. Thermal lags are comprised of the instrumental thermal resistance and the temperature gradient in the film. The instrumental thermal lag was detected by the melting of Tin on the bottom of PE films and well explained by the reported value of the thermal resistance of sensor. The temperature gradient in the film was detected by the melting of Tin on the top surface of PE films, and showed the dependence predicted by the modeling of heat transfer in the thickness direction. The influences of thermal lags have also been examined in terms of the heating rate, β, dependence of the shift in melting peak temperature of PE crystals. The power of βz characterizing the β dependence of the shift became larger with increasing film mass and thickness, i.e. with introducing larger thermal lags. When the power is utilized as a fitting parameter, the influence of thermal lags on the melting point extrapolated to zero heating rate could be kept at small level (±1°C) even for thick films (∼10μm). Those behaviors have been validated by numerical calculations based on the modeling of fast-scan microchip DSC.

Luminescent Characteristics of Fluorescent Organic Pigments Doped Recycled Polyethylene Thin Films Deposited by Ultrasonic Spray Technique at Low Temperature

Fluorescent organic pigments (FOP´s) doped recycled polyethylene (PE) thin films were synthesized by using the ultrasonic spray technique at low temperature. With the objective of minimizing the environmental impact caused by plastic wastes, a new recycling scheme for the fabrication of luminescent polymeric thin films was designed. The recycled plastic bags of Low Density PolyEthylene (LDPE) were used as hosts for the FOP's. The process consisted of spraying an organic solution of LDPE on glass substrates. Later the FPO`s solution was sprayed on top of the LDPE thin films. Several deposition conditions were varied (deposition time, precursor concentration and substrate temperature) to form homogeneous and uniform films. The substrate temperature was low (180°C) in order to avoid thermal degradation of the polymer, as revealed by infrared spectroscopy. These films were doped with different FOP's. Emissions such as blue light emission (λ=434 nm), orange light emission (λ=503 nm) and green light emission (λ=503nm) were obtained by photoluminescence. These FOP´s were mixed to obtain white light emission polymeric films. The thicknesses were close to 1µ. According to Scanning Electronic Microscopy, the LDPE films consisted of small-superposed clusters and the FOP´s were adhered of them. The optical transmission was shown in the 60-80% range.AcknowledgmentsThe authors acknowledge the financial support from SIP-IPN and CONACyT through the scientific research projects (Grant Nos. 20140458, 20140459, 20131915, 20130236, 20130153, 20121399, 129227).

Fabrication of a nano-structured PbO2 electrode by using printing technology: Surface characterization and application

This investigation aimed to introduce printing technology for the first time to prepare a nanostrucutured PbO2 electrode and its application to a cerium redox transfer process. The new method of nano-size PbO2 preparation demonstrated that nano-PbO2 could be obtained in less time and at less cost at room temperature. The prepared nano-PbO2 screen printed on a Ti electrode by three different compositions under similar conditions showed through surface and electrochemical analyses no adherence on Ti and no contact with other nano-PbO2 particles. Gravure printing of nano-PbO2 on a PET (poly ethylene thin) film at high pressure was done with two different compositions for the first time. The selective composition of 57.14 % nano-PbO2 powder with 4.28 % carbon black and 38.58 % ECA (ethyl carbitol acetate) produced a film with a nanoporous structure with an electron transfer ability. Finally, the optimized gravure-printed nano-PbO2 electrode was applied to the oxidation of Ce(III) to Ce(IV) by using cyclic voltammetry. The gravure-printed nano-PbO2 should pave the way to promising applications in electrochemical and sensor fields.

A Polyethylene Chamber for Use in Physical Modelling of the Heat Exchange on Surfaces Exposed to a Radiation Regime

Bodies located in outdoor environments are radiatively heated in the daytime and cooled at night. Convective heat transfer is subsequently activated between the body surface and the surrounding air. To investigate these heat-exchange processes, we developed a new apparatus, referred to as a “polyethylene chamber”, for use in physical model experiments. The chamber is a 1.51-m-long tube with the ends serving as the air inlet and outlet, and is ventilated in the longitudinal direction by using an exhaust fan. The measurement section of the chamber is open but otherwise the device is covered with 0.02-mm-thick polyethylene film. Because such thin polyethylene film transmits approximately 85 % of both shortwave and longwave radiation, the model surface in the chamber is exposed to a radiation level almost equivalent to the outdoor radiation level. For example, at night the surface of the model is cooled by radiation, and subsequently, the air inside the chamber is cooled by the surface. Consequently, the outlet air temperature becomes lower than the inlet air temperature. The use of this temperature difference between the air inlet and outlet, together with other heat balance components, is a unique approach to the chamber technique for evaluating the heat exchange rate at a model’s surface. This report describes the design and heat balance of the chamber, and compares the heat-balance-based approach with another approach based on the radiation–convection balance on the model surface. To demonstrate the performance of the polyethylene chamber, two chambers were exposed to outdoor radiation on a clear night; one contained a leaf model. Air and surface temperatures were measured and the convective heat flux at the surfaces of the model and floor surface were calculated from the heat balance components of the chambers by assuming steady-state heat transfer. The fluxes agreed closely with those obtained from the radiation–convection balance at the model or floor surface. The results also clearly showed that the air flowing in the polyethylene chamber was cooled more efficiently when the model surface was installed in the chamber, even though the model surface temperature was high.

An evaluation of thermal lags of fast-scan microchip DSC with polymer film samples

A quantitative evaluation has been tried on the thermal lags of a fast-scan (≤104 K s−1) microchip differential scanning nanocalorimeter (DSC). A thin layer (∼0.2 μm thick) of a standard material of Tin was vapor deposited on a thin film of polyethylene (PE) sample (∼1–10 μm thick), and the thermal lags have been examined by the dependences on the applied heating rate, film mass, and film thickness of the melting onset temperature of Tin on the bottom and top surfaces of PE films put on the sensor stage of nanocalorimeter. Thermal lags are comprised of the instrumental thermal resistance and the temperature gradient in the film. The instrumental thermal lag was detected by the melting of Tin on the bottom of PE films and well explained by the reported value of the thermal resistance of sensor. The temperature gradient in the film was detected by the melting of Tin on the top surface of PE films, and showed the dependence predicted by the modeling of heat transfer in the thickness direction. The influences of thermal lags have also been examined in terms of the heating rate, β, dependence of the shift in melting peak temperature of PE crystals. The power of βz characterizing the β dependence of the shift became larger with increasing film mass and thickness, i.e. with introducing larger thermal lags. When the power is utilized as a fitting parameter, the influence of thermal lags on the melting point extrapolated to zero heating rate could be kept at small level (±1 °C) even for thick films (∼10 μm). Those behaviors have been validated by numerical calculations based on the modeling of fast-scan microchip DSC.

Strain distribution and load transfer in the polymer-wood particle bond in wood plastic composites

Abstract The load transfer between wood particles and the matrix was analyzed by observation of the strain patterns in thin films of high density polyethylene (HDPE) with embedded wood particles subjected to tensile loading. Optical measurement techniques based on the digital image correlation (DIC) principle were employed for quantitative measurement of strain distributions on the surfaces of the specimens. Interpretation of these measurements in terms of load transfer between the particle and the matrix below the surface proved challenging and required a structured approach. In this paper, quantitative descriptors were selected as synthesized metrics to support the quantitative interpretation of the measured strains. X-ray computed tomography (XCT) scans were used to assess the effect of the position of the particles in the film specimens on the strains patterns observed on the surface.

Measurement of beta-radioactivity distribution in soil by use of fiber-type radiophotoluminescence glass dosimeter

Abstract Fiber-type radiophotoluminescence (RPL) glass dosimeters were satisfactorily made from reagent-grade powders of NaPO 3 , Al(PO 3 ) 3 and AgCl for the measurement of beta-radioactivity distribution in soil. The fiber-type glass dosimeters were covered with thin polyethylene film for the protection of the glass dosimeters against direct contact to soil particles. The RPL intensity of fiber-type glass dosimeters was successfully measured with a confocal microscope together with an ultraviolet pulsed laser. Depth-directional radioactive-cesium distribution in soil at Fukushima was well measured with the fiber-type RPL glass dosimeters and the confocal microscope system.

Monitoring of 222Rn/220Rn concentrations at the work places of Muzaffarabad, Azad Kashmir

Thoron (220Rn), due to its-short half-life of 55.5 s is unable to travel far from its point of generation. A number of studies report indoor radon (222Rn) concentration in different locations of Azad Jammu and Kashmir, while no study reports indoor 220Rn concentration. The CR-39 based passive alpha track detectors were used for the measurement of 222Rn and 220Rn concentrations at different selected workplaces of Muzaffarabad. 222Rn and220Rn concentration were measured simultaneously. Alpha track detectors (ATD) were enclosed in a thin polyethylene film to exclude 220Rn (closed detector) while the other ATD has a coarse metal grid and cloth covering the large entry port allowing for rapid radon gas ingress. The results showed that the measured 222Rn concentration varied from 18.7 Bqm-3 to 160.2 Bqm-3 with an average value of 67.0 ± 3 Bq.m-3. Whereas the 220Rn concentration varied from 14.7 Bqm-3 to 100.4 Bqm-3 with an average value of 50.0 ± 2 Bqm-3. Preliminary results show that indoor 220Rn concentration is significantly higher and should be taken into consideration while calculating the dose due to radiation of natural origin. Key words: Thoron, indoor radon, alpha track detectors, radiation dose, Azad Jammu and Kashmir.

A simple method with imaging plates for examination of soil contaminated with radioactive caesium

A simple and convenient system with imaging plates (IPs) was well constructed for the radioactivity examination of soil contaminated with radioactive caesium. A set of two IP strips was vacuum-sealed with thin polyethylene film to prevent the IP strips from direct contacting soil and from being moisturized. In the examination of radioactive soil, a stainless steel pipe including this IP strip monitor was put into the ground and then it was kept in a lead container after being pulled out of the ground for the reduction of the surrounding gamma-ray background. In addition, a sensitive reader was well made for the measurement of the photostimulated luminescence through the scanning of a laser beam on the IP strip. It was confirmed from experiments on actual radioactive-caesium-contaminated soil that the IP strip monitor with the reader effectively detected beta-rays from radioactive caesium and could be satisfactorily used for the examination of radioactive soil.