Effects Of Moisture Exposure Research Articles

Spectroscopic Investigation of Li3PS4-LiI Sulfide-Based Glass-Ceramic Solid Electrolytes after Moisture Exposure

Sulfide-based solid electrolytes (SEs) have been extensively studied because of their high lithium-ion conductivities. Among the solid electrolytes, glass or glass-ceramic SEs have suitable thermoplastic characteristics for battery manufacturing processes. However, sulfide-based SEs react strongly with moisture, resulting in toxic H2S gas generation and reduced lithium-ion conductivity. Although the effects of moisture exposure on sulfide-based SEs have been investigated by some researchers, related studies are scarce and further research is required. In this study, X-ray photoelectron spectroscopy (XPS) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) were performed to investigate the structural changes in a glass-ceramic sulfide-based SE, viz., Li3PS4-0.2LiI before and after exposure to moisture, focusing on the changes in the surface chemical species, adsorbed H2O, and related species. In addition, SE samples exposed to moist air were subjected to recovery treatment by vacuum heating. XPS and DRIFTS analyses revealed that the main reason for the decrease in the lithium-ion conductivity of the glass-ceramic SE after moisture exposure is the adsorption of water onto the SE surface and/or its hydration. In particular, the H2O layer adsorbed to the SE surface physically and/or chemically decreases the lithium-ion conductivity at the grain boundaries (i.e., SE/SE interface), although the bulk conduction is maintained.

Water distribution and moisture-absorption in egg-white derived peptides: Effects on their physicochemical, conformational, thermostable, and self-assembled properties

Three egg-white derived peptides (DHTKE, MPDAHL, and FFGFN) were characterized with hydrophilia and water distributions. The effect of moisture exposure on their properties at 75% relative humidity for 30 h were further investigated. LF-NMR tests revealed that strong bound-water (relaxation time < 10 ms) accounted for more than 80% of total water in peptides after moisture-absorption. The absorbed water led to the pH of three peptides increase, antioxidant activities in vitro decrease, and diverse changes in their functional group vibrations, molecular hydrophobicity, and phase transformation properties. Compared to dried samples, the hydrated-DHTKE was pyrolyzed and hydrated-MPDAHL was oxidized over 160 °C, while the glass transition, melting, and crosslink temperatures of FFGFN all decreased after moisture-absorption. Moreover, the results indicated that moisture-absorption in FFGFN powder enhanced the surface-hydrophobicity of FFGFN-hydrogel and accelerated its self-organizations. This study provides a comprehensive understanding of moisture-absorption effects on peptides, with these changes potentially impacting storage recommendations and scientific interpretations.

Effect of moisture exposure and elevated temperatures on impact response of Pennisetum purpureum/glass-reinforced epoxy (PGRE) hybrid composites

A Pennisetum purpureum/glass-reinforced epoxy (PGRE) hybrid composites was comprehensively characterised to assess its impact response behaviour at room temperature (RT), under moisture exposure, and elevated temperatures. The untreated, 5 and 10% alkali-treated PGRE composites were fabricated using hybridised Pennisetum purpureum/woven E-glass fibres and epoxy resin. An instrumented IMATEK IM10 drop weight impact tester was utilised to characterise the impact responses of the prepared hybrid composites. The specimens were subjected to water exposure for 50, 100, 200, and 400 h and before arranged with a low-velocity impact test. In addition, the tests were repeated at 40, 60, and 80 °C to examine the effects of elevated temperatures. The results indicate that the untreated PGRE composite yielded the highest peak load impact response at all energy levels. The stiffness of the composites found to decrease substantially with increasing temperatures, which increases the absorbed energy and peak deflection causing extensive damage to the specimens.

Effect of moisture exposure on scratch behavior of model polyurethane elastomers

Effect of moisture exposure on scratch behavior of four model cast polyurethane (CPU) elastomers with different soft segments is investigated. Two model CPU systems contain less polar ether groups and the other two contain more polar ester groups in the soft segment polyols. The ASTM D7027/ISO 19252 standard scratch test was chosen to determine the scratch behavior of the model CPU systems in dry and water-saturated conditions. It is found that the absorbed moisture alters the surface characteristics, mechanical properties and the corresponding scratch behaviors of PU elastomers in different fashions, depending on the PU chemical constituents. The homogeneously absorbed water molecules in the less polar polyether-based PU elastomers serve as plasticizer to degrade the mechanical properties and increase the coefficient of friction (COF), thus leading to deterioration in scratch resistance. However, for the more polar polyester-based PU elastomers, because of the interaction between water molecules and the polar bonding sites, clustering of water occurs on the surface and acts as lubricant to decrease the COF, which improves the scratch resistance. A 3-D finite element method (FEM) modeling was conducted to further understand the observed scratch-induced deformation in the model systems. The present study provides guidelines for preparing scratch-resistant PU elastomers that are exposed to humid environment during service.

Effects of moisture exposure on the crosslinked epoxy system: an atomistic study

Diffusion of water into the polymer structures can influence the structure and properties of the polymers. The absorbed water is believed to degrade the strength and properties of the polymers and hence it is important to study how it affects the thermal and mechanical properties of the polymers. In this report, the effects of moisture on the epoxy network and its properties are studied. The epoxy in this work is considered as the result of the curing of diglycidyl ether bisphenol-A (DGEBA) with JEFFAMINE®-D230 hardener. Several structural and dynamics analysis has been conducted to investigate the effects of the ingress of water into the polymer structure. The significant changes in the epoxy structure as a result of introducing water to the system are observed. The molecular structure has been monitored as it underwent the water uptake process. The variation of the atomic correlations due to the exposure to the moisture is reported. Moreover, the effects of adding water on the glass transition temperature and Young’s modulus is revealed. The changes in the properties are explained by the results obtained from monitoring the molecular structure.

Effect of moisture exposure on scratch resistance of PMMA

Effect of environmental conditioning on scratch performance of polymethylmathacrylate (PMMA) is investigated. Three different grades of PMMA with varying levels of polarity were chosen and their scratch resistance compared in both dry and moist conditions. Linear increasing normal load scratch tests were performed according to ASTM D7027/ISO 19252 standards. Results indicate a drop in scratch resistance with initial exposure to moisture in all three systems. In the two highly polar PMMA systems, the scratch resistance recovers to that of the dry condition after long exposure to moisture. It is proposed that the moisture absorbed initially acts as a plasticizer causing weakening of the surface mechanical integrity. In the case of more polar systems this moisture absorption continues until saturation where water molecules cluster and impart a degree of lubrication and consequently improves scratch resistance.

The effect of moisture absorption on the physical properties of polyurethane shape memorypolymer foams

The effect of moisture absorption on the glass transition temperature (Tg) and the stress/strain behavior of network polyurethane shape memory polymer (SMP)foams has been investigated. With our ultimate goal of engineering polyurethane SMPfoams for use in blood-contacting environments, we have investigated the effects ofmoisture exposure on the physical properties of polyurethane foams. To the best of ourknowledge, this study is the first to investigate the effects of moisture absorption at varyinghumidity levels (non-immersion and immersion) on the physical properties ofpolyurethane SMP foams. The SMP foams were exposed to differing humidity levels forvarying lengths of time, and they exhibited a maximum water uptake of 8.0% (bymass) after exposure to 100% relative humidity for 96 h. Differential scanningcalorimetry results demonstrated that water absorption significantly decreased theTg of the foam, with a maximum water uptake shifting theTg from67 to 5 °C. Samples that were immersed in water for 96 h and immediately subjected to tensile testingexhibited 100% increases in failure strains and 500% decreases in failure stresses; however,in all cases of time and humidity exposure, the plasticization effect was reversibleupon placing moisture-saturated samples in 40% humidity environments for 24 h.

Surface and Buried Interfacial Structures of Epoxy Resins Used as Underfills Studied by Sum Frequency Generation Vibrational Spectroscopy

Flip chip technology has greatly improved the performance of semiconductor devices, but relies heavily on the performance of epoxy underfill adhesives. Because epoxy underfills are cured in situ in flip chip semiconductor devices, understanding their surface and interfacial structures is critical for understanding their adhesion to various substrates. Here, sum frequency generation (SFG) vibrational spectroscopy was used to study surface and buried interfacial structures of two model epoxy resins used as underfills in flip chip devices, bisphenol A digylcidyl ether (BADGE) and 1,4-butanediol diglycidyl ether (BDDGE). The surface structures of these epoxies were compared before and after cure, and the orientations of their surface functional groups were deduced to understand how surface structural changes during cure may affect adhesion properties. Further, the effect of moisture exposure, a known cause of adhesion failure, on surface structures was studied. It was found that the BADGE surface significantly restructured upon moisture exposure while the BDDGE surface did not, showing that BADGE adhesives may be more prone to moisture-induced delamination. Lastly, although surface structure can give some insight into adhesion, buried interfacial structures more directly correspond to adhesion properties of polymers. SFG was used to study buried interfaces between deuterated polystyrene (d-PS) and the epoxies before and after moisture exposure. It was shown that moisture exposure acted to disorder the buried interfaces, most likely due to swelling. These results correlated with lap shear adhesion testing showing a decrease in adhesion strength after moisture exposure. The presented work showed that surface and interfacial structures can be correlated to adhesive strength and may be helpful in understanding and designing optimized epoxy underfill adhesives.

Effect of Storage Conditions on Compaction Behavior of Two Grades of Spray-Dried Lactose

In this work we examine the effect of storage conditions (moisture exposure) on the compression behavior of 2 grades of spray-dried lactose (Pharmatose DCL 11 and Pharmatose DCL 14) under 2 different circumstances. The first was to expose powder samples to moisture, then compress them. The second was to expose precompressed tablets to moisture. We clearly show that the effect of moisture exposure and amorphous content crystallization in spray-dried lactoses on compaction behavior depends on whether this moisture exposure takes place before or after compression. In addition, the impact of storage conditions depends on the grade of spray-dried lactose.

Moisture content penetration in wood elements under varying boundary conditions

Knowledge of effects of moisture exposure on timber structures is important for serviceability and load bearing capacity of timber elements and systems. Varying climate affects the moisture content profiles in timber as the relative humidity changes in the ambient air. This paper presents methods for calculation of diffusion based moisture transport and corresponding results on how timber responds to varying moisture with regard to moisture penetration and distribution. The calculations are based on measured outdoor relative humidity and temperature at different climatic locations in Sweden. No remarkably large deviations between the different climatic locations were found in general, which is positive in a design code perspective.

Physical Characterization Of Microelectronic Polymeric Thin Films

ABSTRACTThe measurement of the mechanical properties and adhesion of polymeric thin films and coatings poses a number of technical problems. Elastic and viscoelastic properties, residual stress, adhesion, the effects of extended cure, and the effects of adsorbed moisture and process reagents are all critical. A particular challenge is to develop measurement methods which can be used with actual samples, preferably non-destructively. This paper examines a number of methods which have been developed to make these measurements, with emphasis on methods which are sensitive enough to look at the effects of process variation and the effects of moisture exposure. Suspended-membrane methods for measuring elastic and viscoelastic properties, residual stress, and adhesion are combined with optical methods for determining index of refraction and birefringence to yield a family of techniques for performing physical characterization. Recent results on the effects of extended cure and moisture uptake on elastic properties, residual stress, and optical properties will be presented.