Effect Of Film Composition Research Articles

Preparation and Curing Behaviour of Epoxy Based Film for Moderate Temperature Prepreg

Bisphenol A epoxy resin and an acid anhydride [chosen from methyltetrahydrophthalic anhydride (Me-THPA), methylhexahydrophthalic anhydride (MHHPA) and methyl nadic anhydride (MNA)] were used to prepare epoxy films for hot melt prepreg. The effects of film composition, i.e. type and amount of epoxy resin, curing agent and curing catalyst, were investigated to develop a moderate temperature prepreg, and orthogonal experiments were used to investigate the effect of film composition on the curing behaviour of the epoxy resin film, and to determine the optimal formulation. The most favourable formulation film was cured at 100 °C for 2 h, and its curing degree was characterised by FTIR spectroscopy.

Platinum/carbon black composites as counter electrodes for high-performance dye-sensitized solar cells

Low-cost counter electrodes for dye-sensitized solar cells (DSSCs) are prepared using platinum/carbon black (Pt/CB) composites via a spin-coating process. Ethyl cellulose (EC) is used as a binder to regulate the viscosity of the Pt/CB composites to facilitate the spin-coating process. The ratio of Pt to CB is ca. 1:3. The effects of film composition (Pt/CB:EC = 30:15, 30:4) and number of coating layers on the electrochemical properties of the Pt/CB electrodes and the performance of the corresponding DSSCs are studied. The results show that Pt/CB films with the lower concentration of EC (Pt/CB:EC = 30:4) exhibit high electrochemical activity, low charge transfer resistance, and good DSSC performance. These results are attributed to the lower loading of EC, which facilitates the charge transfer of the electrodes. DSSCs using these Pt/CB composite counter electrodes with lower loading of EC achieve a high conversion efficiency (8.06%) comparable to that of cells using Pt.

Influence of process parameters on the gallium composition of a CuIn1−xGaxSe2 solar cell on the efficiency of non-vacuum blade coating stacking

The distribution of an energy gap gradient can influence photovoltaic conversion, which in turn influences the performance of solar cells. On the other hand, controlling the energy gap gradient can influence the range of the absorption spectrum, and thus the overall solar photovoltaic conversion efficiency is affected. To control the energy gap of a CuIn1−xGaxSe2 (CIGS) solar cell, this study employs a non-vacuum stack coating technique. The chemical composition of the ink is regulated and a multilayer stack is coated to investigate (1) the distribution range of the energy gap and (2) the variability of conversion efficiency in multilayer stack and single-layer composition conditions, in order to determine the feasibility of using a coating stack design to change and control an energy gap. The effect of film composition on crystallinity is tested through high-temperature selenylation. Finally, a miniature solar module is prepared and the conversion efficiency is found to improve from 5.02% to 7.08%, and the feasibility of energy gap control is demonstrated.

Effects of annealing on the magnetic properties and microstructures of Ta/Mo/CoFeB/MgO/Ta films

We report a study on the evolution of perpendicular magnetic anisotropy (PMA) in Ta/Mo/CoFeB/MgO/Ta junctions annealed at 350 °C for different periods of time. The PMA quickly developed after a short annealing time followed by a slow approach to saturation. This evolution of PMA was accompanied by structural changes. The surface roughness (Rq) gradually increased with increasing annealing time to 30 min; further increases in annealing time resulted in a dramatic increase in Rq. The effects of film composition and chemical state on magnetic anisotropy in the as-deposited Ta/Mo/CoFeB/MgO/Ta films and annealed films were studied. The X-ray photoelectron spectroscopy results demonstrated that more Fe oxides were formed at the CoFeB/MgO interface after 1 min of annealing compared to in the as-deposited sample, which is critical to obtain the PMA. High-resolution transmission electron microscopy analysis revealed that the CoFeB and MgO layers are predominantly amorphous in sample as-deposited and after 1min annealing. However, the CoFeB and MgO layers are crystallized in sample after 30 and 60 min annealing, which is beneficial to get high PMA.

Effects of film composition and substrate orientation on the structure and the magnetic properties of Fe-Co-B alloy films formed on MgO single-crystal substrates

(Fe0.7Co0.3)100−x B x alloy thin films are prepared on MgO single-crystal substrates with (100), (110), and (111) orientations at 200C by ultra-high vacuum radio-frequency magnetron sputtering with various B compositions, x, from 0 to 15 at.%. The effects of composition and substrate orientation on the structure and the magnetic properties are studied. Fe-Co epitaxial films with bcc structures are obtained on all substrates. Fe-Co(100) single-crystal films are formed on MgO(100) substrates. Fe-Co films epitaxially grown on MgO(110) substrates consist of two (211) variants whose orientations are rotated around the film’s normal by 180 each other. Fe-Co(110) films grow epitaxially on MgO(111) substrates with two types of variants, Nishiyama-Wasserman and Kurdjumov-Sachs relationships. As the B composition increases up to around 5 at.%, the film involves an amorphous structure in addition to an epitaxial bcc crystal structure. With further increases in the B content, the film is only amorphous. The magnetization properties of the films involving epitaxial crystals reflect the magnetocrystalline anisotropy of the bulk Fe-Co crystal. The easy magnetization direction varies depending on the crystallographic orientation of the film. Isotropic in-plane magnetic properties are observed for amorphous films.

The effect of film composition on the structure and mechanical properties of NiTi shape memory thin films

Shape memory NiTi-based thin films approximately 2 μm thick were deposited onto Si (100) substrates at room temperature by simultaneous DC magnetron sputter deposition from separate elemental Ni and Ti targets. The effect of composition on film structure, surface morphology, transformation temperature and mechanical behavior was studied using variable temperature X-ray diffraction, atomic force microscopy, electrical resistivity, and nanoindentation. The films showed the expected shape memory and superelasticity behavior corresponding to the different film compositions, comparable with bulk properties. The transformation from the low temperature martensitic phase to the high temperature parent phase takes place above room temperature in Ti-rich and near-equiatomic films, and below room temperature in Ni-rich films. Mechanical properties of films investigated at room temperature by a series of nanoindentations at mN loads (indentation depth < 200 nm) with a spherical indenter demonstrate superelasticity in Ni-rich material and martensitic deformation for Ti-rich and near-equiatomic compositions.

Potato starch edible films to control oxidative rancidity of polyunsaturated lipids: effects of film composition, thickness and water activity

SummaryThe objective of this work was to study the effect of potato starch‐based films acting as oxygen barrier on the oxidative rancidity of vegetable oil, as an example of a food rich in polyunsaturated fatty acids. The effect of glycerol (Gly) content (0%, 10%, 20%, 30%), film thickness (30, 60, 100 μm) as well as environmental relative humidity (RH) (50% or 75%) were analysed. Results obtained confirmed that potato starch films delayed the rancidity in vegetable oil. Films without Gly provided the same protection as films with 10% Gly. Films with higher Gly content were not as effective oxygen barrier. It is likely that the fact that film protective capability diminished with increased RH or Gly content was due to the increasing moisture content of the films. Despite that fact, potato starch films can be considered a very efficient oxygen barrier even at RH as high as 75%.

Potential of Hyperspectral Imaging for Quality Control of Polymer Blend Films

A visible−near-infrared (VIS-NIR) hyperspectral imaging sensor is proposed for online nondestructive monitoring of polymer film blends produced by extrusion blowing. Such a sensor provides a much higher spatial resolution of analysis compared to probes or probe arrays, which should help in detecting smaller localized defects inducing poor film quality (mechanical, optical, barrier properties) at a macroscopic scale. Multiresolutional multivariate image analysis (MR-MIA) was used to extract those spectral and textural features from images that are the most highly correlated to film composition distribution and mechanical properties. When applied to a low-density polyethylene/polystyrene (LDPE/PS) blend produced under various operating conditions, the imaging sensor was able to monitor the two dominant effects on mechanical properties: (1) the effect of film composition (raw materials) and (2) the stretching effect caused by postextrusion conditions (process).

Investigation into the antibacterial property of carbon films

Here we reported the antibacterial characteristics of carbon film and the effect of film composition on its antibacterial performance. Two kinds of carbon films, amorphous hydrogenated carbon film and hydrogen-free carbon film deposited on medical stainless steel using microwave plasma were characterized using Raman Spectra, FT-IR (Fourier transform-infrared spectroscopy), AFM (atomic force microscopy) methods and investigated on their antibacterial property. By the colony-counting method, it was found that the H-free carbon film coating and a-C:H film coating reduced the numbers of E. coli colonies down to about 15% and 33% of those in the original SUS substrate, respectively. The present results suggested that the antibacterial property was strongly related with the chemical inertness of carbon film.

Effects of postnitridation annealing on band gap and band offsets of nitrided Hf-silicate films

The effects of film composition and postnitridation annealing on band gap and valence band offset were examined in nitrided Hf-silicate films prepared using direct plasma nitridation. Regardless of the composition of Hf-silicate films, the band gap characteristics were similar after direct plasma nitridation (4.5±0.1eV) and postnitridation annealing (5.6±0.1eV). The decrease in band gap after direct plasma nitridation was caused by the formation of Si–N and Hf–N bonds, while the recovery of band gap by postnitridation annealing was influenced by the dissociation of unstable Hf–N bonds. The difference in valence band offset was strongly related to the chemical states of Si–N bonds.

Effect of film composition and structure on the crystallization point of atomic layer deposited HfAlO x using metal (diethylamino) precursors and ozone

Atomic layer deposition (ALD) of HfAlO x on Si(1 0 0) was carried out using tetrakis-diethylamino hafnium (TDEAH) and tris-diethylamino aluminum (TDEAA) as metal precursors and ozone as oxidizer. ALD temperature windows of TDEAA and TDEAH overlapped between 200 and 275 °C, which is critical for ALD of composite HfAlO x films. Rutherford backscattering analysis of HfAlO x shows a strong correlation between the number of ALD cycles of alumina and hafnia being alternated and the film composition. Grazing incidence X-ray diffraction analyses of thermally annealed films indicate that a higher Al concentration increases the crystallization temperature and degree of crystallization. In addition to composition, crystallization of HfAlO x film also depends on the film structure defined by the deposition cycle sequence. For example, films deposited by alternating TDEAH/O 3 and TDEAA/O 3 cycles in a 2:1 ratio were found to have a lower degree of crystallization than films deposited by alternating in a 4:2 ALD cycle ratio, even though the ratios of Hf and Al are the same.

Physicochemical characterization of starch based films

In the present study, high amylose corn starch (HACS) based films were obtained with a low temperature method consisted on reduce gelatinization temperature by an alkaline pretreatment of starch. Effects of film composition and preparation method on film properties were investigated to identify HACS film elaboration conditions to improve film properties. Rheological behavior of film-forming solutions is reported. Films were physical and chemically characterized through film solubility in water, water sorption isotherms, opacity and crystallinity of films. Film forming suspensions show pseudoplastic and thixotropic behavior. Apparent viscosity of film forming gel increases exponentially with HACS concentration and Arrhenius law adequately represents variation with temperature. Alkaline treatment time of HACS previous to gelatinization, also affects film properties. It was found that film solubility and opacity decrease while crystallinity increases although it reaches an asymptotic value after treatment time of 60 min. Above 30% of glycerol, an increase in plasticizer content conduces to a looser network, as a result film opacity and water sorption increase.

Experimental set-up and characterization of a mLLDPE-PP co-extruded bilayer system

The rheological behavior of the bilayer system mLLDPE (metallocene linear low density polyethylene)-PP (polypropylene) obtained by a coextrusion process has been investigated in this work. Metallocene polyethylenes are characterized by a superior toughness, heat sealing, and optical properties when compared with conventional polyethylenes. The purpose of the addition of PP in a two layer structure is to confer a better process facility and an enhanced rigidity to the structure itself. A rheological characterization of the two polymers was performed in order to study the flow behavior in each resin, and to verify their compatibility in a coextrusion process. Films, containing different percentages of metallocene polyethylene, were produced by a cast coextrusion process. Moreover, a mathematical modeling of the process was done in order to predict the die pressure gradient, the relative thicknesses, and the shear stress distributions as function of working conditions and rheological properties in the individual polymers. A preliminary investigation on the effect of film composition on the performance of the coextruded bilayers was realized by performing some mechanical tests. POLYM. ENG. SCI. 46:874–881, 2006. © 2006 Society of Plastics Engineers

Whey Protein Film Composition Effects on Potassium Sorbate and Natamycin Diffusion

ABSTRACT: To assess the ability of whey protein films to act as antimicrobial carriers, the effect of film composition on preservative diffusion was investigated. Preservative diffusion coefficients were measured at 24°C in whey protein isolate (WPI) films with different WPI‐glycerol plasticizer ratios (1:1 to 15:1), beeswax (BW) content, 0% to 40% w/w dry solids, and preservative addition of 0.3% (w/w) natamycin or 1.6% (w/w dry solids) potassium sorbate. Diffusion coefficients for potassium sorbate and natamycin were in the ranges 1.09 × 10−11 to 13.0 × 10−11 m2/s and 6.16 × 10−14 to 37.8 × 10−14 m2/s, respectively, and significantly decreased as the WPI‐glycerol ratio increased. No significant difference in sorbate diffusion was seen with the addition of BW.

Bioadhesive Transdermal Film Containing Caffeine

The aim of this work was to investigate in vitro the transdermal permeation of caffeine from a new bioadhesive film, using rabbit ear skin as a barrier. The effects of film composition and of the presence of penetration enhancers in the formulation were studied. The obtained fluxes were compared with those shown by commercial formulations. The results obtained indicate that the bioadhesive film gave rise to a higher transdermal permeation compared to a commercial gel and to a saturated solution of caffeine in water. Additionally, the film did not present the typical time lag of solution and gel. Another peculiar feature of the film is that the percentage of permeated active substance is much higher than that obtained from commercial formulations. Finally, it was possible to modulate caffeine permeation from the film by adding different enhancers/solvents.

Film Composition Effects on Diffusion of Potassium Sorbate Through Whey Protein Films

ABSTRACT: The effect of film composition on potassium sorbate diffusion in whey protein films was studied using mixture response surface methodology. The model developed for potassium sorbate diffusivity was statistically significant (P &lt; 0.01) with no significant lack of fit. The diffusivities of potassium sorbate in the films at 25 °C varied between 5.4 and 9.8 × 10−11 m2/s. Amounts of protein, sorbitol, beeswax, and potassium sorbate in the films significantly affected potassium sorbate diffusion coefficients. Increasing the relative amounts of protein and beeswax in the films decreased potassium sorbate diffusivity, while increasing the relative amounts of sorbitol and initial potassium sorbate in the films increased the diffusion of potassium sorbate. Strong interactions were observed between protein and beeswax, and potassium sorbate and beeswax. Keywords: edible films, whey protein, potassium sorbate, diffusivity, mixture design

The Effect of Film Composition on the Texture and Grain Size of CuInS2 Prepared by Chemical Spray Pyrolysis

AbstractTernary single-source precursors were used to deposit CuInS2 thin films using chemical spray pyrolysis. We investigated the effect of the film composition on texture, secondary phase formation, and grain size. Films with either (112)- or (204/220)-preferred orientation were deposited with most often In-rich composition. The (112)-preferred orientation became more pronounced as the film composition became more In-poor. Films with a (204/220)-preferred orientation were both In-rich and contained a yet unidentified secondary phase. The phase was evaluated as an In-rich compound based on composition analysis and Raman spectroscopy. Further experiments showed that the phase could be removed by depositing a thin Cu layer prior to the growth of CuInS2. Similarly, as-grown Cu-rich (112)-oriented films did not exhibit the In-rich compound. The (204/220) preferred orientation of the film is likely related to the equivalent symmetry between planes of CuInS2 and the In-rich compound. The largest grain size (∼ 0.5μm) was achieved with Cu-rich (112)-oriented films.

Effects of film composition and annealing on residual stress evolution for shape memory TiNi film

TiNi films with different Ni/Ti ratios were prepared by co-sputtering of a Ti50Ni50 (at.%) target with a separated Ti target at a temperature of 723 K. The stress values in the deposited films changed significantly with Ti contents and post-annealing temperatures due to the differences in phase transformation behaviors and intrinsic stress. For the film with Ti content of 51.3%, a two-step transformation was observed among martensite, R-phase and austenite, and residual stress was quite low at room temperature. After post-annealing the above film at 923 K, only one-stage transformation was observed. For the films with Ti contents of 47.3 and 53%, residual stress was quite high due to the high intrinsic stress and partial relaxation of stress caused by the R-phase transformation. When the films with Ti contents of 47.3 and 53% were annealed at 923 K, residual stress in films decreased significantly, because post-annealing could probably modify the film structure, reduce the intrinsic stress, increase the transformation temperatures, and cause martensite transformation above room temperature. For all the three types of films annealed at 1023 K for 1 h, the high thermal stress in the thin films could cause non-recoverable deformation during phase transformation, damage the shape memory effect, and result in the peeling-off of film from Si substrate.

Magnetic hardening mechanism study in FePt thin films

Fe 100−x Pt x alloy thin films with x=25–67 at. % were prepared by dc magnetron sputtering on naturally oxidized Si substrates. Effects of film composition, annealing temperature (300–650 °C), annealing time (5–120 min), and cooling rate (furnace cooling or ice water quench cooling) on the magnetic properties were investigated. Optimum conditions for saturation magnetization and coercivity of the Fe100−xPtx alloy films were found with x=50 at.%, annealed at 600 °C for 30 min and cooled by ice water quenching. Our experimental data suggests that the magnetic hardening in Fe100−xPtx alloy thin films is mainly due to the fct γ1-FePt phase and the domain wall pinning effect. The domain nucleation mechanism is dominated in samples with furnace cooling; the domain wall pinning mechanism dominates in samples cooled with ice water quenching.

Microstructure and magnetic properties of Fe100−xPtx alloy films

Polycrystalline Fe100−xPtx alloy thin films with Pt composition x=25–67 at. % were prepared by dc magnetron sputtering on natural-oxidized silicon wafer substrates, then postannealed in vacuum at various temperatures and over different periods. The effects of film composition, magnetic layer thickness, annealing temperature, and annealing time on the magnetic properties parallel and normal to the film plane were investigated. Films with high in-plane coercivity could be obtained by annealing the films in the temperature range between 400 and 650 °C. Optimum in-plane squareness and coercivity of the film occurred at a film composition of Fe50Pt50 with thickness of about 200 nm after annealing at 600 °C for 30 min. The analyses of transmission electron microscopy diffraction patterns indicated that this annealed Fe50Pt50 film was nearly entirely in the fct γ1-FePt phase. The average grain size of this Fe50Pt50 film was about 85 nm. The grain size was almost independent of the cooling rate after annealing, but the magnetic hardening mechanism and coercivity of the annealed film was largely dependent on the cooling rate.