Method of evaluating moisture barrier properties of encapsulating materials Patent

Method of evaluating moisture barrier properties of materials used in electronics encapsulatio

Moisture Barrier Cone

Closed air space devices and methods of use for all body bio hazard type suits that eliminates condensation and fogging from forming on the face masks and the window visors of the suit. The devices and methods have a sealed closed air space that can be formed from flexible see-through plastic in a cone shape that can be sealed between the mask and the visor. The closed air space can be presealed to the visor/outer wall of the suit and have a second end fitted with an elastic type band that allows the wearer to attache and detach the closed space by wrapping the band about their face mask. Other embodiment use flat see-though plastic sheets, and sheets that attach about the neck of the user to form the closed air spaces between the face mask and the window visor of the suit

The sorption and permeation of moisture in moisture barrier polymer film coatings

Several moisture barrier coatings for use as barriers to moisture uptake into solid dosage forms of moisture-sensitive drug substances are commercially available. The aim of this study was to investigate the moisture sorption and permeation characteristics of four moisture barrier coatings, formulated from the following polymers, i.e., ethyl methacrylate copolymer (Eudragit L30 D-55®), aminobutyl methacrylate copolymer (Eudragit EPO®), poly(vinyl alcohol) (Opadry AMB ®) and hypromellose system (Sepifilm LP 10®). The gravimetric vapour sorption technique, utilising a dynamic vapour sorption apparatus (Surface Measurement Systems, UK), was the main method used to determine the extent of moisture sorption and desorption. Cast free films of the moisture barrier coatings, and uncoated and coated model tablet cores were investigated. The model tablet cores were designed to exhibit hygroscopic, non- hygroscopic or waxy characteristics. Additional tests with near-infrared spectroscopy, thermogravimetric analysis and dissolution testing were done to ascertain the hydration characteristics and/or the water- coating interactions. Sepifilm LP and Opadry AMB films sorbed comparatively more moisture than the Eudragit L30 D-55 and Eudragit EPO films. Differences in hygroscopicity of the films were attributed to differences in the hydrophilicity of the constitutive polymers. Analysis of sorption-desorption kinetics showed that all the film samples exhibited non-Fickian kinetics. The calculated permeability coefficients for moisture in the films were of the order of 10-6 to 10-7 cm3 [(STP) cm/cm2 s cmHg)]. Thus, the moisture barrier coatings were comparatively inferior to conventional barriers like high density polyethylene or polyvinylidene (cling film), with reported permeabilitities of the order of 10-10 to 10-11 [(STP) cm/cm2 s cmHg)]. Application of the moisture barrier coatings onto the model tablet cores resulted in a net reduction in the extent of sorption over the uncoated cores only for the hygroscopic cores. Thus, there was no benefit of applying a moisture barrier coating to the waxy or non-hygroscopic tablet formulations. Results obtained from the stability profile of aspirin used as a model moisture-sensitive compound in the tablet cores confirmed this outcome. However, when the barrier coatings were applied onto the aspirin model cores, the coated samples exhibited higher degradation than the uncoated samples. No correlation between the degradation of aspirin in the cores and the permeability of the films was established. As the moisture barrier coatings were not able to completely seal the tablet cores from moisture uptake, it was speculated the sorbed moisture decreased the adhesion of the coatings to the underlying cores. This facilitated the collection of water at the coating- core boundary, from where aspirin hydrolysis could have taken place. Therefore, if moisture barrier coatings are to protect moisture sensitive compounds in tablet cores, the ability to prevent hydrolysis at the coating-core boundary is deemed essential

Evaluation of moisture barrier coatings on carbon-phenolic SRM nozzle materials

The carbon-phenolic composite ablative material used on the Solid Rocket Motor (SRM) nozzle is known to absorb moisture from the atmosphere. This could cause problems such as pocketing during firing. Several moisture barrier coatings were tested on the SRM nozzle material. Data are presented for six of the 12 coatings to be tested. The data were obtained from immersion of coated samples in an environmental chamber at 100 F and 100% relative humidity and by using a modified TGA (thermal gravimetric analysis) technique. The TGA technique involved allowing wet nitrogen (25 C, 80% relative humidity) to flow across a small sample at about 65 cu cm per minute while continually monitoring the weight increase. These preliminary results show Kel-F-800, a material supplied by 3M Corporation to be the better moisture barrier. A second task was to collect data on the relative absorption of water and kerosene into the carbon-phenolic SRM nozzle material. These data indicate that water absorbs into the nozzle material to a much greater extent than kerosene. Thus kerosene is the more likely solvent in which to make specific gravity measurements on the SRM nozzle material

Evaluation of Moisture Barriers for Fire Fighting Turnout Gear Assessment of Product Failure and Test Method Development Predicting Failure Modes

The purpose of this study was to investigate the failures seen in the moisture barrier of fire fighting turnout gear. Moisture barriers taken from garments in field were evaluated to establish a baseline for comparison. Moisture barriers were exposed as part of a three-piece ensemble and as a single layer moisture barrier to instrumental light exposure in a Carbon Arc Fade-ometer and natural sunlight exposure according to AATCC and ASTM test methods. After exposure, moisture barriers were visually examined using stereo and compound microscopes. A performance measurement was conducted on the exposed moisture barriers using a modified NFPA Hydrostatic Water Penetration Resistance Test. Results of the instrumental and natural sunlight exposures were compared to the failed garments from the field. The results showed that moisture barriers were degraded by ultraviolet light and replicated some of the results seen in the field to predict failures. Based on the results of this study, suggestions were made for future research for developing a test method for predicting moisture barrier failures

Experimental Model of Suction Head on Expansive Soil Subgrade with Concrete Wall Moisture Barrier

Soil expansivity generally occured caused by the presence of a clay mineral of smectite group, such as montmorillonite, illite, bentonite, etc, which could absorb so much water. The impact of losses incurred by soils ekspansivity on buildings and infrastructure primarily on lightweight structures are staggering. Technology is often applied as a solution to problems such as improvement of material characteristics, providing early treatment of constructive and structural engineering support to overcome the adverse effects of expansive soil. Erecting concrete moisture barrier on the side of the road is a combination of the provision of early treatment and support in structural engineering change control water content in the soil layer of expansive.This study aims to determine the behavior of suction, moisture barrier effects on suction head reduction, and the experimental model of suction head profile with the erecting and testing of the models tested in the laboratory.The test model was made to resemble half of the road width with a load of 30 kPa on it. On the side of the road mounted concrete wall moisture barrier with a variation of the depth of 20 cm, 35 cm and 50 cm. Observation of time and water absorption carried out on 8 observatories, also the amount of swelling through a dial that is placed above the concrete slab load. The results showed an increase in capillary water in front bulkhead for all variations of depth moisture barrier and water absorption height reduction occurred in the rear bulkhead respectively 3.25%, 21.25% and 45% for the ratio of height bulkhead and expansive soil thickness h/H = 0.44, h/H = 0.78 and h/H = 1.11. Also the reduction of swelling respectively by 4.46%, 52.69% and 82.53% for each ratio h/H above

Ultra-long-term reliable encapsulation using an atomic layer deposited Hfo2/Al2o3/Hfo2 triple-interlayer for biomedical implants

Long-term packaging of miniaturized, flexible implantable medical devices is essential for the next generation of medical devices. Polymer materials that are biocompatible and flexible have attracted extensive interest for the packaging of implantable medical devices, however realizing these devices with long-term hermeticity up to several years remains a great challenge. Here, polyimide (PI) based hermetic encapsulation was greatly improved by atomic layer deposition (ALD) of a nanoscale-thin, biocompatible sandwich stack of HfO2/Al2O3/HfO2 (ALD-3) between two polyimide layers. A thin copper film covered with a PI/ALD-3/PI barrier maintained excellent electrochemical performance over 1028 days (2.8 years) during acceleration tests at 60 °C in phosphate buffered saline solution (PBS). This stability is equivalent to approximately 14 years at 37 °C. The coatings were monitored in situ through electrochemical impedance spectroscopy (EIS), were inspected by microscope, and were further analyzed using equivalent circuit modeling. The failure mode of ALD Al2O3, ALD-3, and PI soaking in PBS is discussed. Encapsulation using ultrathin ALD-3 combined with PI for the packaging of implantable medical devices is robust at the acceleration temperature condition for more than 2.8 years, showing that it has great potential as reliable packaging for long-term implantable devices

Transition from glass to graphite in manufacture of composite aircraft structure

The transition from fiberglass reinforced plastic composites to graphite reinforced plastic composites is described. Structural fiberglass design and manufacturing background are summarized. How this experience provides a technology base for moving into graphite composite secondary structure and then to composite primary structure is considered. The technical requirements that must be fulfilled in the transition from glass to graphite composite structure are also included