Thick PET Film Research Articles

High-performance coaxial reversal rotational triboelectric nanogenerator based on charge pumping strategy driving tip high voltage breakdown

Triboelectric nanogenerator (TENG) serves as an effective method for harvesting mechanical energy from the surrounding environment. Nonetheless, its practical application is hindered by issues such as inadequate charge density and wear of friction surface materials. Here, a high-performance self-supplementing coaxial inverse triboelectric nanogenerator (HSCI-TENG) based on charge pumping supplementary strategy is presented, which operates in non-contact mode and increases surface charge density with almost no friction loss. The coaxial reversal design facilitates dual-speed rotation, resulting in a significant enhancement of the output current. Furthermore, an innovative approach was employed by affixing four layers of 0.06 mm thick PET film to the storage electrode, thereby augmenting the threshold of electrode charge storage and effectively mitigating the risk of electrode breakdown. At a rotation speed of 300 rpm, the peak-to-peak voltage, peak-to-peak current, and charge transfer of HSCI-TENG are 3340 V, 360 μA and 0.97 μC, respectively. Excellent stability is demonstrated through 10000 cycle tests on the output of HSCI-TENG. In particular, the maximum output power is 770 mW at a load resistance of 8×106 Ω. The high-performance HSCI-TENG has been proven to be a stable energy source driving high voltage breakdown sensor system. The tip high voltage breakdown exhibits high frequency and continuity, with 14 breakdowns occurring within 10 seconds. Besides, HSCI-TENG has potential to serve as an energy source for high-pressure sterilization, high-pressure dust removal, and water electrolysis systems.

Tensile Control of Vibrational Strong Light‐Matter Coupling with Flexible Polyester Films

AbstractPolaritons are generated by strong interaction between photons and matter, with the hybridization fundamentally changing the energy landscape of the system. Future exploitation of polaritons will benefit from implementing low‐cost, flexible, and easily tuneable configurations, as electronics have before. Here, coherent coupling of the carbonyl stretch vibrations of polyester (poly(ethylene terephthalate), PET) films to the optical modes of a Fabry–Perot (FP) cavity is presented, in which the FP cavity is directly formed on flexible, free‐standing, and commercially available PET films. For 2‐µm thick PET films, the carbonyl stretch vibration of the PET overlaps with the half‐wavelength FP cavity mode, leading to the coupling of the two modes, a Rabi splitting above 160 cm−1, and associated anticrossing in angular dispersion measurements. The study demonstrates dynamic control of light‐matter interaction strength by modulating film thickness under tension, finding that a 25% tensile stretch can tune the light‐matter interaction from 20:80 mixing to near‐perfect 50:50 hybridization at normal incidence. These findings are discussed in the context of future foldable/twistable/wearable polaritonic devices.

P-205L:Late-News Poster: Improvement of Viewing Angle Dependence and Out-Coupling Efficiency of OLEDs with Strong Microcavity Structure by Introduction of Nanoporous Polymer Films

To improve a viewing angle characteristic as well as a light extraction effect, we fabricated nanoporous polymer film (NPF) as a scattering medium as well as a light extraction component. We designed two types of organic light emitting diodes (OLEDs) with strong microcavity effect containing two different hole transport layer (HTL) thickness (e.g. 30 nm and 60 nm) to investigate each optical behavior of NPF. Very interestingly, we could observe a significant enhancement of external quantum efficiency (EQE) for each device [30 nm thick HTL : 18.0 %, 60nm thick HTL : 31.6 %] when we attached 125 um thick PET film coated with NPF. Furthermore, NPF successfully suppress the viewing angle dependence to realize ideal angular emission even though it's somehow different from that of Lambertian distribution.

A nanoporous polymer film as a diffuser as well as a light extraction component for top emitting organic light emitting diodes with a strong microcavity structure.

To improve the viewing angle characteristic as well as the light extraction effect of strong microcavity devices, we fabricated a nanoporous polymer film (NPF) as a scattering medium as well as a light extraction component. We designed two types of organic light emitting diodes (OLEDs) with a strong microcavity effect by changing the thickness of the hole transport layer (HTL; e.g., 30 nm and 60 nm) to investigate two different scattering effects of the NPF. Very interestingly, we could observe a significant enhancement of the external quantum efficiency (EQE) for each device (30 nm thick HTL: 18.0%, 60 nm thick HTL: 31.6%) when we attached a NPF formed on a 125 μm thick PET film coated with the NPF. Furthermore, the NPF successfully suppressed the viewing angle dependence to realize ideal angular emission even in the two extreme microcavity conditions although they are still different from that of a Lambertian distribution.

AFM probing of polymer/nanofiller interfacial adhesion and its correlation with bulk mechanical properties in a poly(ethylene terephthalate) nanocomposite.

The interfacial adhesion between polymer and nanofiller plays an important role in affecting the properties of nanocomposites. The detailed relationship between interfacial adhesion and bulk properties, however, is unclear. In this work, we developed an atomic force microscopy (AFM)-based abrasive scanning methodology, as applied to model laminate systems, to probe the strength of interfacial adhesion relevant to poly(ethylene terephthalate) (PET)/graphene or clay nanocomposites. Graphite and mica substrates covered with ∼2 nm thick PET films were abrasively sheared by an AFM tip as a model measurement of interfacial strength between matrix PET and dispersed graphene and clay, respectively. During several abrasive raster-scan cycles, PET was shear-displaced from the scanned region. At temperatures below the PET glass transition, PET on graphite exhibited abrupt delamination (i.e., full adhesive failure), whereas PET on mica did not; rather, it exhibited a degree of cohesive failure within the shear-displaced layer. Moreover, 100-fold higher force scanning procedures were required to abrade through an ultimate "precursor" layer of PET only ∼0.2-0.5 nm thick, which must be largely disentangled from the matrix polymer. Thus, the adhesive interface of relevance to the strength of clay-filler nanocomposites is between matrix polymer and strongly bound polymer. At 90 °C, above the bulk PET glass transition temperature, the PET film exhibited cohesive failure on both graphite and mica. Our results suggest that there is little difference in the strength of the relevant interfacial adhesion in the two nanocomposites within the rubbery dynamic regime. Further, the bulk mechanical properties of melt mixed PET/graphene and PET/clay nanocomposites were evaluated by dynamic mechanical analysis. The glassy dynamic storage modulus of the PET/clay nanocomposite was higher than that of PET/graphene, correlating with the differences in interfacial adhesion probed by AFM.

Development of Numerical Model and Coupled Thermal/Mechanical Analysis in the Laser Transmission Joining of PET and Stainless Steel

Laser transmission joining of dissimilar and biocompatible materials has potential applications in biomedical implants. In this work, a three-dimensional (3D) transient model for sequentially coupled thermal/mechanical analysis of laser transmission joining of 0.1mm thick PET film and 0.1mm stainless steel has been developed by using the ANSYS parametric design language APLD, along with a moving Gaussian laser heat source. It can be calculated how long it takes to reach the quasi-steady state through the stimulation of the temperature field. The calculated values of the joint width are in good agreement with the experimental results by comparison under conditions of different parameters, which indicates that the model is reliable and is helpful for optimizing process parameters. Then based on the temperature field, the residual stress field distribution on both PET and stainless steel surface is achieved by applying the indirect coupling methods to the analysis. this study also has laid a theoretical foundation for improving the stress distribution on the joint.

Optimization of Laser Transmission Joining Process between Different Thermoplastics using Response Surface Methodology

In order to determine the optimum joint conditions, four key process parameters affecting the joint quality of laser transmission joint of 1mm thick PET film and PC film，namely，laser power, scanning speed, clamping pressure and scanning number are optimized by response surface methodology in this paper. The interaction effect of main process parameters on joint quality is researched. The samples are tested using a multi-axis microtester in order to determine joint strength. The morphology of the joining area is observed with an optical microscope. Design Expert analysis indicates that the best laser power, scanning speed, clamping pressure and scanning number on joint quality were 35.7W, 5.0mm/s, 0.75MPa, 3, respectively. Finally, the experimental results are consistent with the predicted, which illustrates that the developed mathematical models can predict the responses adequately.

Optimization of Laser Transmission Joint between PET and Titanium Using Response Surface Methodology

Laser transmission joint between biocompatible, dissimilar materials have the potential for application in biomedical and their encapsulation process. This paper is devoted to laser transmission joint between 0.1mm thick PET films and 0.1mm thick Titanium using near-infrared diode lasers. Response surface methodology (RSM) is used to develop mathematical models between the joining process parameters. The developed mathematical models are tested for adequacy using analysis-of-variance (ANOVA) method. In addition, the main effect of each parameter and the interaction effects with other process parameters are analyzed. Finally, the experimental results agree with those predicted indicate that the developed mathematical models can predict the responses adequately.

Laser transmission joint between PET and titanium for biomedical application

Laser transmission joint between biocompatible, dissimilar materials have the potential for application in biomedical and their encapsulation process. This process may involve photochemical reaction, and alter the chemical compositions of the interface and chemical bonds form at the interface. Understanding the laser joint at material interfaces is essential for the advancement in the laser joining application. This paper is devoted to laser transmission joint between 0.1 mm thick PET films and 0.1 mm thick Titanium. We have found processing conditions for successful joining of titanium with PET using near-infrared diode lasers. Laser joint samples were tested in microtester under tensile loading to determine joint strengths. The joint strength was found to be 65.46–90 MPa. The PET/titanium interfaces thus obtained were studied by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy coupled with energy dispersive spectroscopy (SEM/EDS) and microscopy techniques. The results give evidence for the formation of Ti–C chemical bonds in a sharp interfacial region between the two sides. These chemical bonds are believed to be responsible for the observed mechanical strength of the joints.

Manufacture of dual-side surface-relief diffusers with various cross angles using ultrasonic embossing technique

This paper reports a simple and effective ultrasonic embossing method which enables the rapid fabrication of dual-side surface-relief plastic diffusers with various cross angles. Metallic master molds bearing microstructures are fabricated using a tungsten carbide turning machine. A 1500-Watt ultrasonic vibrator with an output frequency of 20 kHz was used to replicate the microstructure onto 1 mm thick PMMA and PET films in the experiments. During ultrasonic embossing, the ultrasonic energy is converted into heat through intermolecular friction at the master mold/plastic plate interface due to asperities to melt the thermoplastic at the interface and thereby to replicate the microstructure. Under the proper processing conditions, high-performance dual-sided plastic diffusers of various cross-angles can be successfully fabricated. The proposed method shows great potential for fast fabrication of micro-optical components due to its simplicity and versatility.

Analysis and fabrication of a prism film with roll-to-roll fabrication process

A prism-based brightness enhancement film (BEF), has been investigated through computer-aided optical analysis and experiments in this study. The prism film was fabricated on a 100 microm thick PET film substrate using roll-to-roll (R2R) process with UV curable resins of different refractive indices. The results from both optical analysis and experiments showed that resins with higher refractive indices have better on-axis luminous gain. The prism structures fabricated on the substrate achieved a replication rate of 97.54% in this study. Compared with the 3M BEF, the prism films developed in this study are improved in on-axis luminous gains when the refractive index of the resin is higher than 1.53.

DLC coatings on inner walls of PET bottles by a simplified PBII technique

Some research has been carried out on DLC coating of inner walls of PET bottles because the DLC coating can reduce the oxygen transmission rate through the wall of the bottles drastically. Existing techniques for DLC formation on the inner wall of PET bottles require rather complicated coating systems. In this study, we propose a simple way to coat DLC on the inner walls using a modified PBII technique. The configuration is that the outer wall is covered by an outer electrode connected to a grounded vacuum chamber and an inner electrode, which is connected to a positive high voltage pulsed power supply, is inserted inside the bottle. In the coating process, the bottle is filled with C 2H 2 gas at a suitable pressure. Using this approach we have succeeded in coating DLC on the inner walls of bottles. Oxygen and nitrogen gas transmission rates were examined for 20-s, 1-min and 5-min coating times on 50-μm thick PET films. We found that the DLC coatings reduce the rates drastically, and a 1-min coating time is enough to form a gas barrier. The results of micro-scratch tests for the DLC-coated PET films show good adhesion of the DLC coating and reduction of friction. The Meyer hardness and Young's modulus of the DLC-coated PET films were also estimated from the penetration depth–load relationship obtained by a depth sensing indenter with a diamond spherical indenter 200 μm in radius. It is revealed that for the 5-min coated film the apparent Meyer hardness at 5-mN load and Young's modulus were about 1.4 and 1.2 times larger than those of the uncoated film, respectively.

Adhesion Strength of Polymer Coatings studied by Laser Induced Delamination

ABSTRACTLaser Induced Delamination is a novel technique aimed at quantification of adhesion of thin polymer films to a metal substrate. In this technique a high power IR pulsed laser beam (maximum 500 mJ in 5 ns) is used to create the primary delaminated area in the form of a blister. The blister is formed due to heating of the metal substrate and because of partial evaporation of the polymer material adjacent to the interface. By varying the power of the laser pulse the gas pressure inside the blister is increased until further delamination takes place. This critical pressure is related to the strength of adhesion of the polymer to the substrate. The shape of the blister (radius and height) is controlled with a stylus profiler and with an optical confocal microscope.In the present work 30 μm thick PET films on steel substrate were studied. From the shape of the obtained blisters the strength of adhesion of the polymer is estimated. Various models describing blister formation and growth are discussed.

A method for local application of thin organic adhesive films on micropatterned structures

The application of adhesive films can be an important step in the manufacturing process of micromechanical structures if precise control of very small volumes of the adhesive over small contact areas is guaranteed. Residues of adhesives outside the joint area are to be avoided. Conventional microdispensers allow the handling of volumes down to about 1 nl. Recent developments employ techniques used in ink jet printers and are capable of delivering single drops of adhesive with volumes as low as 5 pl. Some micromechanical joints may require volumes even lower (an adhesive joint of 200 nm thickness over an area of 10 μm × 10 μm requires for instance a volume of 0.02 pl). The method developed for this purpose involves the deposition of a thin organic adhesive film by a spin coating process and the controlled transfer to (and only to) the intended locations on the micromechanical structure. One benefit of this method is increased design flexibility due to extension of the range of combinations of conventional thin film technology with other materials such as polymer films. The method was tested by preparing small cavities and other simple three-dimensional microstructures where it was mandatory to prevent the adhesive filling up the voids between the contact areas. Examples of composite structures made of 0.6 μm thick PET films glued to micropatterned structures on silicon substrates are presented.

Characterization of Poly(Ethylene Terephthalate) Using Near and Far FTIR Spectroscopy

The use of near infrared and far infrared spectroscopy for characterization of poly(ethylene terphtalate) films is discussed. After a brief review of previous work, some examples of transmission spectra of annealed PET, showing complex changes in the absorption bands, are presented. NIR spectra was used to follow the crystallinity (or conformation) of thick PET films without any sample preparation.

Roll-to-roll microwave pecvd machine for high-barrier film coatings.

The authors have recently introduced Ovonic Clearcoat, an ECD process using a silica barrier coating technology for plastic films, for use in packaging applications. The 120Å thick coating on 0.5mil thick PET film, deposited in pilot roll-to-roll equipment provides excellent water vapor barrier performance of less than 1g/m2/24 hrs. and excellent oxygen barrier performance of less than 1ml/m2/24 hrs. Additionally, the barrier coating is transparent, colorless, flexible, microwavable and retortable.ECD's process utilizes proprietary low-pressure microwave plasma-enhanced chemical vapor deposition (PECVD) process to deposit high quality SiOx type coatings at high deposition rates.A patented deposition process, incorporating a serpentine pass line, facilitates high speed roll-to-roll vacuum deposition. The microwave-induced plasma deposition area is enclosed by the moving web. Consequently, the deposition area is large and the gas utilization factor is high. The combination of high deposition rate and efficient utilization of actives species leads to a high-speed process. The deposition takes place on the non-cooled surface of plastic film which travels at high speeds. Use of the microwave plasma process provides highly energetic depositing species which form denser and higher quality coatings, even at the low substrate temperature required for plastic films.The authors have applied the ECD process to a number of polymer films now on the market. The barrier properties of these polymers coated by the process are found to be superior.