Film Shrinkage Research Articles

Operationally Ready Advancements in Oil Free Corrosion Control for Advanced Materials

Operationally ready is a key component to effective management of equipment, spares and systems through manufacturing, shipment and transport, meaning that products are impacted by how they stored, shipped and staged. That means no rust, no degradation and the ability to utilize the equipment or parts quickly, with no cleaning or additional work required. Significant advancements have been made in oil free, volatile free anti-corrosion protection to aid this. These advancements are in the form of plastics, laminates, canvas, woven products and shrink films that can be used to provide long term stable packaging that can be used both as short term, one-time use, multiple use applications or even used to create portable storage shelters. These materials will also help stabilize and help protect metals as well as non-metallic components and materials such as items that can swell, gaskets, fabric and rubber components, against degradation – this is critical since many systems are combination of materials, no longer just single material construction. These developments in oil free, volatile free packaging have been successfully incorporated into automotive applications with short term and long-term protection being available from the same packaging. Additionally, information on accelerated testing on already environmentally stressed items will be reviewed and solutions presented to their protection schemes as well.

Comparison of apparatus and methods for tactile marking of polymeric films with Braille alphabet

This article analyzes contact and non-contact methods for local heat treatment of heat shrink films in tactile marking devices. The characteristics of polymeric film heating processes under heat transfer from metal stamps and laser emitters were investigated. The article contains diagrams obtained by differential scanning calorimetry of polymeric heat shrink film exposed to thermal effect of different tactile marking devices. The article also describes stereometry of Braille elements obtained by using a metal stamp and a laser emitter.

A humidity fiber sensor based on both end-sides of a fiber Bragg grating coated with polyimide

A humidity fiber sensor based on both end-sides of a fiber Bragg grating (FBG) coated with polyimide has been proposed and demonstrated. Polyimide is coated on both end-sides of FBG, and a thermal curing treatment is performed to form a dense film of a certain shape. The reflection centre wavelength of the FBG is shifted 0.5 nm by bring prestress to bear on the FBG, and then the two ends of this FBG are fixed on a base with ultraviolet (UV) glue. This structure will not damage the grating part of FBG and ensure the bandwidth and reflectivity of the FBG keeping stable. In addition, this sensor avoided the curing shrinkage of the moisture sensitive film, chirp effect caused by uneven coating or the warpage of the film caused by thermal curing. The experimental results showed that the sensor has a linearity of 99%, a sensitivity of 3–4 pm/%RH and an accuracy of 5% over a wide RH range from 20 to 95%. Furthermore, this sensor has a small hysteresis, better long-term stability and simple structure and can realize multi-point quasi-distributed sensing, which has broad application prospects.

Experimental study of steady seepage in unsaturated loess soil

The complexity of unsaturated soil means that its permeability coefficient and seepage law are important topics in soil mechanics and geotechnical engineering. In this study, a new type of equipment for measuring the seepage of unsaturated soil was used to study the steady seepage of unsaturated loess soil collected from northern Shaanxi province in China. The entire process of the steady seepage of unsaturated soil under different seepage hydraulic gradients was obtained, and the permeability coefficient in the steady seepage state was measured. When the soil water content was low, the soil moisture remained only in small pores or at the junction of soil particles, the effective seepage area of the sample was reduced, and the seepage path was extended. Therefore, the lower the water content, the smaller the permeability coefficient of unsaturated soil and the longer the time required for the seepage to reach a steady state. The matric suction of the unsaturated loess soil was measured under different water contents. With decreasing water content, water remained only in the smaller pores, which provided shrink films with a smaller radius of curvature. This allowed the shrink films to withstand a larger pore air pressure and transmit a smaller pore water pressure, so that the matric suction of the loess soil increased with decreasing soil water content. The Gardner model provided an accurate fit of how the matric suction varied with the volumetric water content of the unsaturated soil. The seepage velocity and seepage hydraulic gradient were correlated well with a linear relationship, indicating that the seepage law of unsaturated loess soil accords with Darcy’s law. The experimental results show that the new unsaturated soil permeameter has good performance and controllability, thereby providing support for studying the steady seepage of unsaturated soil.

Alleviation of enzymatic browning and maintenance of postharvest quality of litchi (Litchi chinensis) fruit with packaging films

The present study was carried out during the years 2016–17 and 2017–18 to evaluate the effect of different packaging films for control of pericarp browning and maintenance of postharvest quality of litchi (Litchi chinensis Sonn.) fruits during cold storage. Litchi fruits of cultivar Dehradun were harvested at physiological mature stage and de-stalked. The fruits were packed in low density polyethylene film (LDPE, 25 μ), high density polyethylene film (HDPE, 10 μ) and heat shrinkable film (15 μ). The control fruits were packed with in gunny sack with litchi leaves as per traditional technique.The fruits were then stored in walk-in-cold store (2-3°C and 90-95% RH) for 4 weeks. The results revealed that LDPE packaging film proved to be the most effective in minimizing the pericarp browning of litchi fruits. LDPE film resulted in reducing the weight loss, browning index and maintained, organoleptic quality, TSS, acidity, ascorbic acid and gave the best browning inhibition during the storage by reducing the activities of polyphenol oxidase and maintained a higher level of total anthocyanin. The data revealed that litchi fruits packed in LDPE films can be stored successfully up to three weeks with acceptable marketable quality.

Effects of pea protein on properties of cassava starch edible films produced by blown-film extrusion for oil packaging

Abstract Starch can be commercially prepared into edible and biodegradable packaging via plasticization and extrusion. However, plasticized starch has poor stability in blown-film extrusion processability and storage properties which can be improved by combinations with protein. Edible films were developed from acetylated cassava starch (AS) and pea protein isolate (PI) using conventional blown-film extrusion. Films with PI up to 20 % were determined for physical, thermal and barrier properties and stability for oil packaging. PI stabilized films during blown-extrusion but decreased flexibility due to strong inter- and intra-molecular interaction with non-homogeneity of AS-PI blend matrices. Protein dispersed in AS matrices at low PI and formed continuous networks at 20 % which led to increased tensile strength. Increase in PI decreased solubility and light transmission but increased protein aggregation and improved crystallinity, surface hydrophobicity and barrier properties against water vapor and oxygen. Increase in PI also reduced glass transition and relaxation temperatures of AS-PI blends. Heat-sealed AS and AS-PI sachets showed effective protection for soybean and olive oil stored for 3 months at different humidities. PI blending effectively prevented humidity-induced shrinkage of AS film (up to 55 %) and enhanced polymer-glycerol interaction which improved thermal stability. Blending of starch and plant-derived pea protein effectively improved blown-film processability and barrier properties for oil-based food products.

Multi-step proportional miniaturization to sub-micron dimensions using pre-stressed polymer films.

The ability to define patterns and fabricate structures at the nanoscale in a scalable manner is crucial not only in integrated circuit fabrication but also in fabrication of nanofluidic devices as well as in nano and micromechanical systems. Top down fabrication at the nanoscale often involves fabrication of a master using a direct write method and then its replication using a variety of methods such as by hot embossing, nanoimprint lithography, or soft lithography. Nevertheless, fabrication of the master is a time consuming and expensive process. One interesting approach is to define patterns at larger dimensions on pre-stressed films using methods such as xurography or lithography which are scalable and heat them to de-stress and shrink which can reduce the size proportionally. Although attractive, suitable fabrication processes that can perform iterative shrinking of patterns over several cycles and into the nanoscale have not been demonstrated. Here, we demonstrate a fabrication process that is capable of accurately producing patterns and features over several cycles of miniaturization and shrinking to achieve resolution in the order of 100 s of nanometers. In this approach, a pattern transfer method is developed by combining soft imprint lithography followed by reactive ion etching, both of which are scalable processes, to transfer the original patterns into a shrinkable polymer film. The patterned shrinkable film is heated to allow thermal shrinking. As a result, the pattern size was decreased by 60% of the original size in a single cycle. This reduced pattern was used as the master for the next cycle and three cycles of miniaturization was demonstrated. Sub-micron patterns of 750 nm were generated by the multi-step miniaturization method, showing approximately 20× reduction in size of the original patterns. Finally, these patterns are transferred into features on a silicon substrate to demonstrate its application in semiconductor microfabrication or its use as a master template for microsystems applications.

Strong enhancement of gold nanoparticle chemiresistor response to low-partitioning organic analytes induced by pre-exposure to high partitioning organics.

Exposing a thiol-functionalised gold nanoparticle film chemiresistor to methanol in aqueous solution results in only a small electric current response as the thiol ligand/water partition coefficient of methanol is small, leading to only minor swelling of the chemiresistor film. Nevertheless, the current response to methanol can be enhanced if the chemiresistor becomes pre-exposed to a molecule with a large ligand/water partition coefficient P (e.g. octane with Po = 104.3). The large response enhancement is achieved because methanol, when added to an aqueous solution of octane, lowers the large initial partition coefficient of octane. Octane exiting the thiol ligands then leads to strong film shrinkage resulting in a relative current change much greater than the one otherwise induced by methanol alone. This was theoretically modelled for octane and heptane (Ph = 103.6). A strong response enhancement to methanol (>20 times) was observed experimentally by exposure to 2 ppm octane compared to direct testing of methanol in aqueous solution. Besides octane and heptane, molecules with P > 107 (e.g. permethrin) can theoretically be used to provide enhancement factors of several orders of magnitude. For practical reasons, heptane and octane saturate more quickly, thus enabling more rapid detection of methanol than higher P organic molecules.

Effect of pulsed electric field treatments on melanosis and quality changes of Pacific white shrimp during refrigerated storage

Polyphenoloxidase (PPO) from Pacific white shrimp was subjected to Pulsed electric field (PEF) at varying specific energy (54-483 kJ/kg) and pulse number (200-600). PPO activity was decreased as both parameters increased (P < 0.05). Among shrimp treated with PEF, those subjected to PEF-T3 (483 kJ/kg, 600 pulses) had the lower melanosis score than other PEF treatments and the control, packaged in polystyrene trays and wrapped with shrink film, during 10 days of storage at 4 °C (P < 0.05). Highest shear force values were noticed with PEF-T3 treated sample at the end of storage period (day 10) (P < 0.05). Microstructural gaping between shrimp muscle fibers was notably higher in PEF-T3. No protein degradation was observed for all samples, regardless of PEF treatments. Lower mesophilic and psychrophilic microbial counts in shrimp were obtained when PEF-T3 was implemented. After 10 days of storage, higher sensory scores of PEF-T3 treated samples were also attained, as compared to others (P < 0.05). Quality deterioration of shrimp was retarded with the aid of PEF.

Blowing Properties and Functionality of Thermoplastic Polyester Film Using Thermally Expandable Microcapsules.

Blowing film was prepared using a polyester elastomer with thermally expandable microcapsules to investigate its blowing properties and functionality. Film with 11% microcapsule contents showed the lowest specific gravity and the highest blowing efficiency. However, the collapse and merging of blowing cells with 11% microcapsule contents was found by SEM. Therefore, film with 9% microcapsule contents was shown to have better blowing and cell stability than that of film with 11% microcapsule contents. Tensile strength and elongation decreased by increasing microcapsule contents. Film curl and film shrinkage properties were unaffected by microcapsule contents. Water vapor permeability and hydrostatic pressure was decreased by increasing microcapsule contents.

Effect of irradiation conditions by swift heavy ions on the microstructure and composition of PMMA

Our research is devoted to the shrinkage and swelling of PMMA film after micro-structuring with ion beam lithography. 10 MeV O4+ ions were used in the experiment. Parallel lines of 1 mm in length and 10 μm in thickness were created. The number of scan cycles and ion fluence were varied. The influence of the irradiation regime on PMMA elemental composition in micro-structured parts and microstructure morphology were studied. It was shown that microstructures created in PMMA film undergo both shrinkage and swelling processes depending on both the scan speed and the fluence. For the same fluence, shrinkage appears at fast scan speeds and swelling at slow ones. The same phenomenon was found in relation to the fluence for the same scan speed. It was observed that PMMA film rupture caused by irradiation occurred prior to the start of the carbonization of the irradiated area.

Improving appearance of 3-coat-1-bake multilayer films on automotive bodies through solvent composition design

3-coat-1-bake (3C1B) is a wet-on-wet-on-wet coating method in which three layers, consisting of a primer-surfacer, basecoat, and clearcoat, are coated consecutively without baking. The 3C1B method is widely applied to automobile paint because of its low energy consumption. However, the appearance of the coated surface is usually inferior to films obtained by the 2-coat-1-bake coating method. The main cause of this difference is presumed to be the waviness of the substrate surface and the waviness of the interfaces between the primer-surfacer/basecoat and the basecoat/clearcoat layers, which are telegraphed to the coating surface. The waviness of the coating surface increases as the coating film shrinks, and decreases as the surface of the coating film flows. Increases in waviness occur as the shrinkage process of the coating film proceeds. Conversely, waviness decreases as the flow and leveling process proceeds. The degree of waviness depends on the balance between volume shrinkage and flow/leveling. Consequently, reducing the shrinkage is an effective means of improving the appearance of a 3C1B coating film. Therefore, if the level of high-boiling-point solvent, which is used for leveling, remains significant while the flow and leveling process is stopped by the extent of the cure, film shrinkage caused by the evaporation of the remaining solvent might telegraph the waviness of the substrate and interfaces to the surface and degrades appearance. This study verified this assumption. When preparing a 3C1B coating film using a waterborne primer-surfacer, waterborne basecoat, and solventborne clearcoat, the solvent that remains in significant quantities while the flow and leveling process is stopped, is mainly an ether-ester-type high-boiling-point organic solvent mixed with the clearcoat as a leveling agent. This solvent was replaced by a low-boiling-point ether-ester-type solvent or an ether-alcohol-type solvent. As a result, in addition to lowering the boiling point, the shrinkage after end of the flow and leveling process was decreased and the appearance was improved. Thus, it was concluded that the origin of the poor surface appearance of the 3C1B coating is the residual high-boiling-point solvent (used as a leveling agent) in the wet coating film.

Enhanced alumina film adhesion of Hf/Y-doped iron–aluminum alloys during high-temperature oxidation: a new observation

The cyclic oxidation behavior of Hf/Y-doped B2 FeAl intermetallics at 1373 K was investigated. For an undoped FeAl alloy, premature spallation of the alumina film occurs due to the formation of numerous voids at the film/alloy interface and apparent shrinkage in the film. In contrast to this, doping with either Hf or Y significantly improves the interfacial adhesion between the alumina film and the alloy substrate, particularly with Hf-doping. Microstructural observation in combination with Auger electron spectroscopic analysis suggests that in addition to prohibiting interfacial void formation and alleviating film shrinkage, the addition of Hf in the FeAl alloy could consolidate the film/alloy interface by directly participating in chemical bonding across the interface as a Hf ion. This causes the spallation of alumina film from the equiaxed grains/columnar grains interface rather than the bottom of the film.

Facile synthesis and characterization of novel multi-functional bio-based acrylate prepolymers derived from tung oil and its application in UV-curable coatings

With the growing depletion of fossil energy and the unceasing joint efforts to maintain sustainable development, bio-based materials are appealing for academic and industrial researchers because they possess the merits of environmental friendliness and renewability. In this study, a tung-oil-based derivative, tung-maleic anhydride (TMA), which was prepared from methyl eleostearate and maleic anhydride, reacted with epichlorohydrin to synthesize epoxidized tung-maleic anhydride (ETMA) after the hydrolysis of anhydride. Furthermore, ETMA was chemically modified by pentaerythritol triacrylate to obtain hexa-functional epoxidized tung-maleic anhydride acrylate prepolymers (PETMA). The chemical structure of the resultant prepolymers was confirmed by FT-IR and 1H NMR, while the rheological behavior of prepolymers was investigated by using a rheometer. Also, the curing efficiency of different photoinitiators on PETMA prepolymers was investigated, and the result revealed that the tung oil-based prepolymers could be rapidly cured with 3.0 wt% photoinitiator PI-819 under a UV lamp with 5 kW light intensity within 45 s. Furthermore, various reactive diluents were used to be cured with PETMA prepolymers, and the thermomechanical properties, mechanical properties, volume shrinkage, swelling property, and general performances of the resultant UV-cured films were investigated. DMA results revealed that, among the films cured by the reactive diluents with same functionality, reactive diluents with a higher Tg resulted in a higher Tg toward the resultant cured films. The crosslinking density (νe) of the films cured with various reactive diluents was determined by the double bond density, leading to the fact that the films cured with bi-functional reactive diluents exhibited a higher crosslinking density than the ones cured with mono-functional reactive diluents. TGA results showed that high crosslinking density facilitated improving the thermal stability of the cured films, while the steric structure in film matrix exerted adverse effect on thermal stability. Besides, tensile test indicated that high crosslinking density and steric structure facilitated the enhancement of mechanical properties toward the resultant films. More strikingly, all UV-cured films possessed excellent hardness, high glossiness and remarkable water resistance, and these high-performance bio-based UV-curable films are promising for widespread applications.

Performance enhancement of solar-assisted liquid desiccant dehumidifiers using super-hydrophilic surface

Solar-assisted liquid desiccant dehumidification technology is attracting much attention due to lower energy consumption and less pollution. This study aims at adopting surface-modification technology to improve the dehumidification efficiency and analysing the energy saving of solar-assisted liquid desiccant air-conditioning system. Firstly a novel super-hydrophilic coating was successfully fabricated using nanoscale anatase TiO2 particles with high dispersion. The characterization of the coating was conducted using X-Ray Diffraction (XRD) and Field Emission Scanning Electron Microscopy (FESEM) test. After surface treatment, the surface free energy was significantly increased from 15.71 to 90.15 mJ/m2 and the contact angle was rapidly reduced from 90° to 10° Then, an experimental system with two single-channel plate-type liquid desiccant dehumidifiers was designed. The experimental results indicated that the falling film shrinkage of desiccant solution was effectively prevented and the contact area was rapidly increased by the novel coating. The maximum wetting ratio was increased from 75% to almost 100%. The influence of operating parameters on heat and mass transfer performance was comprehensively analysed. To better evaluate the benefits of the surface-modification technology, a dynamic model of solar-assisted liquid desiccant air-conditioning system was developed. The simulation results indicated that 9% (94MW · h) of electricity could be saved. This finding is very useful in other falling film applications, such as heat exchangers and cooling towers to improve the efficiency and reduce the energy consumption.

Photochemical low-temperature synthesis of iron(III) oxide thin films

Amorphous iron(III) oxide thin films have been prepared by vacuum ultraviolet (VUV) photochemically initiated oxidative conversion of [Fe(OtBu)3]2 at ambient temperature and pressure. The decomposition process and kinetics for conversion of [Fe(OtBu)3]2 precursor film thicknesses of 109–330 nm to much thinner and crack-free iron(III) oxide films (38–54 nm) were investigated. Due to the film shrinkage, higher densities as compared to hydrolysis (3.15 vs. 2.6 g cm−3) could be achieved. Mechanistic insight by DFT calculations and FTIR spectroscopy suggests the formation of intermediate Fe(CO2)-ring structures throughout the photochemical conversion process. Resulting iron(III) oxide layers were almost carbon free and exhibiting high transparency in the visible range. The proposed photochemical synthesis pathway represents an attractive route in achieving a dense metal oxide coating at low temperatures, e.g. for coating onto thermally sensitive substrates.

P‐136: Research of COP Film shrinkage on Flexible Touch Sensor Process

This paper mainly studied the influence of the preparation process conditions (temperature, lamination direction, film structures, etc.) on the shrinkage of COP (Cycio Olefins Polymer) film flexible touch sensor The temperature is the main influence factor of the shrinkage of COP film flexible touch sensor With the temperature increasing from 100 ° C 60 min to 130° C 60 min, the shrinkage factor increases from 0.07% to 0.39%. Also, the lamination direction has a great influence on the shrinkage of COP film. After 130° C 60 min baking, the shrinkage factor of TD (perpendicular to the direction of Lami) is 0.39%, while the shrinkage factor of MD is 0.43%. The shrinkage factor has 0.04% difference between the TD&amp;MD. Meanwhile, the OC (organic coating) film and ITO thickness cause less than 0.01% shrinkage factor. Compared to the effects of temperature, this 0.01% shrinkage factor can be ignored. Therefore, in the flexible touch sensor process, temperature management is very important.

PDMS-based microfluidic devices with shrinkable wax molds printed on biaxially orientated polystyrene film

This study proposed a novel method for the fabrication of shrinkable wax mold for PDMS-based microfluidic devices. In this approach, the designed wax patterns were printed on the surface of a thermally shrinkable polymer film (biaxially orientated polystyrene) with a commercial wax printer. Then a thermal treatment process was conducted, which simultaneously triggered wax reflow and shrinkage of the polymer film. After cooling, finer wax patterns with increased aspect ratio were achieved. Finally, wax patterns on polymer film can be used as the mold for the casting of PDMS-based microfluidic devices. Compared with previous approaches for the fabrication of molds for PDMS, the proposed fabrication method is more rapid, low-cost, non-toxic and without the requirement of cleanroom facilities or photolithography instruments. In addition, the use of thermally shrinkable polymer substrate helps to achieve an increased aspect ratio, as well as finer and higher wax patterns. And the wax patterns could be used as the mold for the fabrication of PDMS-based microfluidics.

Improved heat shrinkage and mechanical performances of polyethylene trilayer blown film prepared via novel multilayer coextrusion method

In this work, polyethylene (PE) trilayer blown film was prepared using a self‐made rotating coextrusion blown film die (RCBD) with the aim to manufacture trilayer film with excellent comprehensive heat shrinkage and mechanical performances. Polymer resins in this unique blown film die are subjected to a complicated flow field combining both shear circulation and pressure flow. As a result, the melt shows a helix movement in our novel die. The effect of additional parameter (mandrel rotation speed) on the heat shrinkability and mechanical properties of trilayer film was investigated and compared with that of various blow‐up ratios (BURs). The shrinkage rate and shrinkage force along transverse direction (TD) were significantly improved by the mandrel rotation, rather than BUR. Similar trends were observed in tensile strength along TD. However, no considerable changes in heat shrinkability and mechanical properties of PE films along machine direction (MD) were observed. In summary, samples prepared at mandrel rotation speed of 4 rpm were obtained excellent comprehensive performances. Moreover, the morphological investigations confirmed that the formation of high ordered lamellae could be induced by mandrel rotation, and the row structure of oriented lamellae tended to incline to TD under higher rotation speed of mandrel. Besides, the crystal dimension and percent crystallinity were increased because of the mandrel rotation.

Effects of nuclear and electronic stopping powers on the conversion of hybrid silicate thin films

A study of the effects of nuclear and electronic stopping powers on the ion irradiation-induced conversion of hybrid silicate thin films is presented. The films were synthesized by sol-gel processing from a combination of tetraethylorthosilicate (TEOS) and methyltriethoxysilane (MTES) precursors and were spin-coated onto a Si substrate. After drying at 300 °C for 10 min, the films were irradiated with either 400 keV N2+ or 1 MeV Cu+ at fluences ranging from 1 × 1013 to 1 × 1016 ions/cm2. The ion species and energies were chosen such that electronic stopping powers were similar while nuclear stopping powers varied. The electronic and nuclear stopping powers of the ions in the films were calculated as a function of depth. The effects of stopping power on the film conversion were studied in terms of film shrinkage and nanomechanical response by utilizing atomic force microscopy and nanoindentation. Ion irradiation at lower fluences had a negligible effect on the hardness and reduced elastic modulus. However, after ion irradiation with a fluence of 1 × 1015 ions/cm2, the film irradiated with 1 MeV Cu+ had higher hardness and elastic modulus compared to the film irradiated with 400 keV N2+, suggesting the mechanical properties of the resulting thin films were related to both the electronic and nuclear stopping powers. After ion irradiation with a fluence of 1 × 1016 ions/cm2, the difference in the hardness and elastic modulus of the two irradiated films became smaller.