Moisture Resistance Properties Research Articles

Effects of deposition temperature on optical properties of MgF2 over-coated Al mirrors in the VUV**Project supported by the West Light Foundation of the Chinese Academy of Sciences and the National Natural Science Foundation of China (Grant No. 61805247).

Both long-term environmental durability and high reflectance of protected-Al mirrors are of great importance for developing the optical instruments in the vacuum ultraviolet (VUV) applications. In this paper, the dependence of spectral property and environmental durability of MgF2 over-coated Al mirrors using a 3-step method on deposition temperature of the outermost MgF2 layer are investigated in detail. Optics (reflectance), structure (surface morphology and crystalline), and environmental durability (humidity test) are characterized and discussed. The results show that both optical and moisture-resistant properties of MgF2 over-coated Al mirrors are dependent on MgF2 deposition temperature, and the optimal deposition temperature for the outermost MgF2 layer should be between 250 °C and 300 °C for MgF2 over-coated Al mirrors to have both reasonably high reflectance in the VUV spectral range and high moisture resistance for long lifetime applications.

Preparation of water-based epoxy resin and its application as an automotive air filter paper binder

Water-based epoxy resin emulsion was prepared by emulsifying o-cresol formaldehyde epoxy resin with self-emulsified epoxy curing agent synthesized in this study and then used as an environmentally friendly binder for automotive air filter paper. The preparation process of the self-emulsified epoxy curing agent was confirmed by Fourier transform infrared spectroscopy (FTIR). The effects of neutralization degree (Neu) and amount of curing agent on the formation of epoxy resin emulsion were studied. The micro-morphology and size distribution of the epoxy resin latex were characterized by transmission electron microscopy (TEM) and dynamic and static light scattering, respectively. The micro-structure of the air filter paper surface was studied by scanning electron microscope (SEM). The mechanical strength and moisture-resistance properties of air filter strengthened by the prepared water-based epoxy resin emulsion was tested and compared to three commercial binders. The prepared epoxy resin emulsion greatly enhanced the mechanical properties and moisture-resistance properties of the air filter paper while maintaining its filtration properties. Therefore, the epoxy resin emulsion can be used as an environmentally friendly water-based binder for automotive air filter paper with excellent comprehensive properties.

Pt/Al2O3 with ultralow Pt-loading catalyze toluene oxidation: Promotional synergistic effect of Pt nanoparticles and Al2O3 support

A kind of highly efficient and low cost supported-Pt catalyst for oxidation of toluene is obtained through controlling both the chemical state of Pt active sites and surface properties of supports. The optimized Pt/Al2O3 catalyst with Pt loading as low as 0.1 wt% could completely convert toluene (1000 ppm) to CO2 at about 180 ℃ under a space velocity of 24,000 mL g−1 h−1. It also exhibits a high stability and moisture resistance properties under reaction atmosphere. TOF value calculated with the dispersion of Pt can reach 0.0685 s-1, representing a high utilization efficiency of Pt. A series of characterizations are carried out to investigate the key factors affecting the catalytic performance of Pt/Al2O3, and disclose the concrete role of Pt and Al2O3 in the activation of molecular oxygen and toluene. In situ DRIFTS and EPR results show that Pt is the active center for O2 activation. Metallic Pt nanoparticles (Pt0) can activate the molecular O2 even at room temperature. Al2O3 offers sites for the adsorption of toluene and desorption of CO2 product. The weak and medium strength of acid-base sites favorite the adsorption and desorption process. The oxidation of toluene over Pt/Al2O3 obeys modified L-H mechanism. The synergistic effect of metallic Pt nanoparticles and suitable Al2O3 support is critical for obtaining highly efficient Pt-based catalysts with low Pt contents for toluene oxidation.

Moisture-Resistant Sealing Materials for Downhole HPHT Electrical Feedthrough Package

Abstract A bismuth oxide–based multicomponent glass system, xH3BO3-yBi2O3-(1-x-y-δ)MO-δ· rare earth oxides (REOs) with MO = TiO2, BaO, ZnO, Fe2O3, etc., and lanthanum series–based REOs, for making downhole high-pressure and high-temperature electrical feedthrough package has been developed using high-temperature melt-quenching and sintering technologies. By properly controlling phase structures in material-manufacturing processes, the obtained sealing materials have shown moisture-resistant properties in their monoclinic and tetragonal mixed phase structures but strongly hydrophobic properties in their covalent bond tetragonal phase. Sealed electrical feedthrough packages have been evaluated under boiling water immersion and 200°C/30,000 PSI water-fluid–simulated downhole harsh environments. The post electrical insulation measurement has demonstrated to be greater than 1.0 × 1014 Ω electrical resistance. This article will show that such a high–bonding strength and high–insulation strength sealing material could be used to seal electrical feed-throughs and connectors for 300°C/30,000 PSI downhole and subsea wireline, logging while drilling, and measurement while drilling tools' signal, data, and electrical power transmissions.

Moisture-resistant sealing materials for downhole HPHT electrical feedthrough package

Abstract A bismuth oxide based multi-component glass system, xH3BO3-yBi2O3-(1-x-y-δ)MO-δ·REO with MO=TiO2, BaO, ZnO, Fe2O3, etc., and lanthanum series based rare earth oxides (REO), for making downhole high-pressure and high-temperature (HPHT) electrical feedthrough package, has been developed using high-temperature melt-quenching and sintering technologies. By properly controlling phase structures in the material manufacturing processes, the obtained sealing materials have shown moisture-resistant properties in their monoclinic and tetragonal mixed phase structures, but strongly hydrophobic properties in their covalent bond tetragonal phase. The sealed electrical feedthrough packages have been evaluated under boiling water immersion and 200°C/30,000PSI water-fluid simulated downhole harsh environments. The post measurement has demonstrated to be greater than 1.0×1014 Ω electrical resistance. This paper will show that such a high-bonding-strength and high-insulation-strength sealing material could be used to seal electrical feedthroughs and connectors for 300°C/30,000PSI downhole and subsea wireline, logging while drilling (LWD), and measurement while drilling (MWD) tools' signal, data, and electrical power transmissions.

Biocompatible Polymers for the Synthesis of Nanosalts via Supramolecular Ion-Dipole Interaction.

High salt (NaCl) consumption is critical for many healthy problems, e.g., high blood pressure, heart attack, and stroke. Nanosized NaCl particles hold great promise for reducing salt intake; however, they suffered from deliquescence due to their large surface area. We report a facile yet general strategy for the preparation of NaCl nanoparticles (nanosalts) with controllable sizes and moisture resistance property by using biocompatible polymers, such as polyethylene glycol, polyvinylpyrrolidone, polypropylene glycol, polylactic acid, polycaprolactone, and copoly(oxyethylene/oxypropylene/oxyethylene) via supramolecular ion-dipole interaction. The size can be tuned in a range of 100-160 nm by changing the molecular weight or concentration of polymer ligands. Nanosalts protected by polymers showed faster dissolution rate and better moisture resistance compared with microsized NaCl particles without polymer ligands. This work promotes the future development of nanosalts for food and industrial applications to improve human health.

An Attempt of Using β-Sitosterol-Corn Oil Oleogels to Improve Water Barrier Properties of Gelatin Film.

Oleogel with tailored viscoelasticity is a great interest for food structuring, while its potential benefits for edible film performance are not clear. In this study, β-sitosterol (0, 5, 10, 15, and 20 wt%)-corn oil oleogel was developed and used in the formation of gelatin-based films. Importantly, adding oleogel significantly decreased water vapor permeability of the gelatin films, however, it had little negative influence on film strength. In addition, the results of this study demonstrated that increasing the sitosterol in oleogels led to an increasing number of ordered crystals formed in the oleogel, which contributed to compact and smooth surface of the film. Moreover, the incorporation of oleogel also caused some changes in molecule conformation and film barrier property. Therefore, the superior mechanical performance and moisture resistance properties of the film were obtained when 15% β-sitosterol was used to prepare oleogel. PRACTICAL APPLICATION: Corn oil oleogels β-sitosterol was incorporated with gelatin to prepare the gelatin film aiming to improve the water resistance of the films for its variety of practical production. The enhanced vapor permeability and accepted strength of the emulsion film indicated the potential application of it with a variety of edible packaging forms, such as films, pouch and sachet in medium and high humid condition.

Moisture-induced damage resistance, stiffness and fatigue life of asphalt mixtures with different aggregate-binder adhesion properties

Abstract This study investigated the effects of aggregate-binder adhesiveness on moisture damage and on fatigue life of four different asphalt mixtures. Adhesivemeness was assessed by: (i) qualitative observation of binder stripping from the coarse aggregate’s surface, incremented in this paper with digital image processing, and (ii) modified Lottman test. Fatigue damage modeling was performed, using tension-compression test results. The granitic aggregate produced mixtures with better moisture resistance and fatigue properties when compared to the phonolitic aggregate (same ranking as for aggregate-binder adhesiveness). The same was observed for mixtures with binder containing an anti-stripping agent. It was demonstrated that mixtures with better aggregate-binder adhesiveness have greater fatigue life.

Improved Mechanical and Moisture-Resistant Properties of Woven Hybrid Epoxy Composites by Graphene Nanoplatelets (GNP).

This research investigated the effect of adding different wt.% (0, 0.25, 0.50, and 0.75) of GNP (graphene nanoplatelets) to improve the mechanical and moisture resistant properties of Kevlar (K)/cocos nucifera sheath (CS)/epoxy hybrid composites. The laminates were fabricated with different K/CS weight ratios such as 100/0 (S1), 75/25 (S2), 50/50 (S3), 25/75 (S4), and 0/100 (S5). The results revealed that the addition of GNP improved the tensile, flexural, and impact properties of laminated composites. However, the optimal wt.% of GNP varies with different laminates. A moisture diffusion analysis showed that the laminates with a 0.25 wt.% of GNP content efficiently hindered water uptake by closing all the unoccupied pores inside the laminate. Morphological investigations (SEM and FE-SEM (Field Emission Scanning Electron Microscope)) proved that the addition of GNP improved the interfacial adhesion and dispersion. Structural (XRD and FTIR) analyses reveals that at 0.25 wt.% of GNP, all the hybrid composites showed a better crystallinity index and the functional groups presents in the GNP can form strong interactions with the fibers and matrix. A statistical analysis was performed using One-way ANOVA, and it corroborates that the mechanical properties of different laminates showed a statistically significant difference. Hence, these GNP-modified epoxy hybrid composites can be efficiently utilized in load-bearing structures.

Cure Kinetics and Properties of High Performance Cycloaliphatic Epoxy Resins Cured with Anhydride

In this work, a cycloaliphatic epoxy resin hexahydrophthalic acid bis(3,4-epoxycyclohexylmethyl) ester (BE) was prepared and cured with anhydride. The curing kinetics and properties of the cycloaliphatic epoxy resin were characterized and compared with (3′,4′-epoxycyclohexane) methyl-3,4-epoxycyclohexyl-carboxylate (CE) and bis(3,4-epoxycyclohexylmethyl) adipate (BA). The result shows that BE/4-methyl hexahydrophthalic anhydride (MHHPA) exhibits a higher reaction activation energy and a slower curing rate than CE/MHHPA and BA/MHHPA. The loss modulus of BE/MHHPA increased 53 and 24% compared to CE/MHHPA and BA/MHHPA, respectively. The Young’s modulus and initial degradation temperature of BE/MHHPA improved 31 and 6.4% compared with those of BA/MHHPA. Furthermore, superior moisture resistance and dielectric properties are expressed for BE/MHHPA among these epoxy resins. Those results demonstrated the potential usefulness of BE/MHHPA in the electronic packaging materials field.

Improving the moisture resistance and luminescent properties of K2TiF6:Mn4+ by coating with CaF2

The moisture resistance and luminescent properties of K2TiF6:Mn4+ (KTF) phosphor was enhanced through a facile coating method to modify its surface, in which CaF2 was used as a coating material. The structure, morphology, and composition of the KTF@CaF2 samples were investigated via power X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), and transmission electron microscope (TEM). The luminescence properties were identified by luminescence spectra. The results show that, after being treated with CaF2, the surface morphology changed to some extent, and the luminous intensity of phosphor was enhanced. Through application of a moisture resistance test, the luminous intensity of KTF@CaF2 phosphor was maintained, whereas the KTF was hydrolysed and the luminous intensity decreased. This was ascribed to local distortion of the crystalline field around Mn4+ in phosphors and the improvement of surface moisture resistance of phosphors after coating with CaF2.

Improving moisture stability of SrLiAl3N4:Eu2+ through phosphor-in-glass approach to realize its application in plant growing LED device

Herein, we present a simple strategy to enhance the stability of water-sensitive SrLiAl3N4:Eu2+ phosphor through embedding the phosphor particles into low-melting Sn-P-F-O glass using phosphor-in-glass (PiG) approach. After being immersed in water for 96 h, the emission intensity of the SrLiAl3N4:Eu2+-PiG sample was maintained at 80% of its pristine intensity, indicating the moisture-resistance property of SrLiAl3N4:Eu2+ was significantly enhanced. Employing the narrow-band red-emitting SrLiAl3N4:Eu2+-PiG sample and a blue COB (chip-on-board), a plant growing LED device was fabricated. The emission spectrum of the device matches well with the absorption of Chlorophyl (a and b) in plants, indicating the as-prepared SrLiAl3N4:Eu2+-PiG are suitable to be applied in plant lighting field. We believe that this simple method reported in this communication can be easily expanded to other water-sensitive luminescence materials.

Geometric Characteristics of BOF Slag Coarse Aggregate and its Influence on Asphalt Concrete.

In order to examine the geometric characteristics of BOF (blast oxygen furnace) slag coarse aggregate, the aggregate image measurement system (AIMS) was used to analyze the sphericity, gradient angularity and micro texture. Both volumetric and mechanical properties were studied to evaluate the influence of geometric characteristics of BOF slag coarse aggregate on asphalt concrete. The experimental results show that the BOF slag coarse aggregate has the characteristics of high sphericity, good angular performance and rough surface texture. The geometric characteristics of BOF slag has obvious influence on the volume performance of asphalt concrete. the higher sphericity of BOF slag causes an increase of the air voids of asphalt mixture. BOF slag coarse aggregate can effectively improve the road performances of asphalt concrete. BOF slag’s higher sphericity and angularity improve the moisture damage resistance and rutting resistance of asphalt concrete. Results indicate that better angularity can slightly enhance the moisture resistance property of asphalt concrete, but excessively high angularity of BOF slag coarse aggregates reduces the anti-rutting properties of asphalt mixture.

Moisture-Resistant Mn4+ -Doped Core-Shell-Structured Fluoride Red Phosphor Exhibiting High Luminous Efficacy for Warm White Light-Emitting Diodes.

K2 TiF6 :Mn4+ is a highly efficient narrow-band emission red phosphor with promising applications in white light-emitting diodes (LEDs) and wide-gamut displays. Nevertheless, the poor moisture-resistant properties of this material hinder commercialization. A convenient reverse cation-exchange strategy is introduced for constructing a core-shell-structured K2 TiF6 :Mn4+ @K2 TiF6 phosphor. The outer K2 TiF6 shell acts as a shield for preventing moisture in the air from hydrolyzing the internal MnF6 2- group, while effectively cutting off the path of energy migration to surface defects, thereby increasing the emission efficiency (especially for the phosphors doped with high concentrations of Mn4+ ). Employed as a red phosphor, the packaged white LED exhibits an extraordinarily high luminous efficacy of 162 lm W-1 , a correlated color temperature (CCT) of 3510 K, and a color rendering index of 93 (Ra ). Aging tests performed on this device at 85 °C and 85 % humidity for 480 h retain up to 89 % luminous efficacy. The findings could facilitate commercial application of K2 TiF6 :Mn4+ @K2 TiF6 phosphor.

A comparative study of characterization and water absorption behaviour of polyester composites with inorganic and organic fibers

Abstract The research deals with fabrication and characterization of h-BN composites with polyester as the matrix material as well as hybrid composites incorporating inorganic as well as organic filler. The inorganic ceramic filler like h-BN tends to enhance the thermal properties and imparting moisture resistant properties whereas organic fillers like Peanut husk increases the strength and stability of the composites. The implications of embedment of h-BN on the thermal conductivity (keff), mechanical characteristics, and morphological parameters are apprehended. It is observed that increase in filler content increases the effective thermal conductivity. With 35 wt% of h-BN the improvement of keff is appreciably elevated to 23.69%.In case of hybrid composites, the keff value decreases to some extent due to insulative property of peanut husk fibers but shows an improvement in mechanical properties with addition of peanut husk fibers. Therefore, thermal conductivity is compromised a little for achieving a balance between physical, mechanical and thermal properties. Though theoretical Rule of Mixture model aids to be well co-correlation to estimate keff for spherical Boron Nitride particles in composites, a better model is proposed for the same. At about filler volume fractions more than 20%, there is a conductivity jump in the composites because of the interaction between Boron Nitride particles and matrix forming conductive networks and this phenomenon occurs at a volume fraction called the percolation threshold. Hence, with higher thermal conductivity and good mechanical properties with very low water absorption, composites with appropriate amount of particulates can be utilized in various fields like heat engine laminates, engine casings, military equipments, fins and heat sinks, printed circuit board substrates etc. where faster heat transfer is a necessity.

Effects of glycerides with different molecular structures on the properties of maize starch and its film forming capacity

To investigate the effect of glycerides with different molecular structures on the properties of maize starch (MS) and its film forming capacity, the complexing index, swelling power, diffraction patterns and thermograms of MS-glyceride complexes were measured, and the moisture resistance and mechanical properties of MS-based films were studied. The glycerol monolaurate (GML) more strongly interacted with amylose molecules than did glycerol monostearate (GMS) or glycerol tristearate (GTS). The swelling power of MS decreased with the addition of glycerides. X-ray diffraction demonstrated that the diffraction intensities of amylose-lipid inclusion complexes decreased with increasing acyl chain lengths and increased as the number of stearyl chains increased. Addition of glycerides inhibited the gelatinization process of native MS. The melting enthalpies (△H) of amylose-lipid complexes followed the order: GML > GTS > GMS. MS-based film with glycerides showed higher tensile strength values, lower elongation at break values and better moisture resistance than native starch-based film. The composite film with GML showed better mechanical properties and moisture resistance than the composite film with GMS and GTS.

Effects of using brake pad waste powder as a filler material on the rheological and mechanical properties of a sulfur modified asphalt mixture

Thiopave sulfur product has been recognized as a kind of asphalt-binder replacement agent providing the asphalt mixture with better anti-rutting performance. However, there is often a concern about its poor resistance to the moisture damage and the low temperature. This study investigated the applicability of brake pad waste (BPW) in the sulfur modified asphalt mixture as a means to enhance its moisture, cracking, and high temperature-rutting resistance properties. The laboratory manufactured BPW powder with a size less than 0.075 mm was used as filler to substitute the limestone powder with different proportions. The effect of the BPW powder on the physical and rheological properties were assessed by the penetration test, the softening point test, the ductility test, and the dynamic shear rheometer test. In addition, the effect of the BPW on the properties of the sulfur modified asphalt mixture was evaluated using the Hamburg wheel tracking test, the freezing-thawing test, the dynamic uniaxial compression test, the semi-circular bending test, and the fatigue test. The results showed that the BPW could improve the high temperature properties of the sulfur modified asphalt mixture. In general, the anti-rutting performance of the sulfur modified asphalt mixture increased as the BPW increased. Optimum anti-moisture and anti-cracking properties of the sulfur modified asphalt mixture were also found to occur at 50% BPW powder content of the whole filler content. At an applied micro-strain of less than 300 με, the sulfur modified asphalt mixture with 50% BPW powder exhibited the longest fatigue life, with an increasing trend as the micro-strain decreased. In general, 50% BPW powder content was found to be the optimal and best substitution dosage for the limestone filler at all the laboratory performance indices that were evaluated.

Influence of Furfuryl Alcohol Fiber Pre-Treatment on the Moisture Absorption and Mechanical Properties of Flax Fiber Composites

Poor moisture resistance of natural fiber reinforced bio-composites is a major concern in structural applications. Many efforts have been devoted to alleviate degradation of bio-composites caused by moisture absorption. Among them, fiber pre-treatment has been proven to be effective. This paper proposes an alternative “green” fiber pretreatment with furfuryl alcohol. Pre-treatments with different parameters were performed and the influence on the mechanical properties of fiber bundles and composites was investigated. Moisture resistance of composites was evaluated by water absorption tests. Mechanical properties of composites with different water contents were analyzed in tensile tests. The results show that furfuryl alcohol pretreatment is a promising method to improve moisture resistance and mechanical properties (e.g., Young’s modulus increases up to 18%) of flax fiber composites.

Thermoplastic starch and glutaraldehyde modified thermoplastic starch foams prepared using supercritical carbon dioxide fluid as a blowing agent

Supercritical carbon dioxide (scCO2) processed thermoplastic starch (scCO2aTPS), cellulose nanofiber (CNF) modified scCO2aTPS (scCO2aTPS100CNF0.02) and glutaraldehyde (GA) modified scCO2aTPS100CNF0.02(scCO2aTPS100CNF0.02GAx) foams were prepared for the first time using scCO2as a blowing agent during their foaming processes. The expansion ratio, cell density, moisture resistance, and compressive strength (σc) retention properties of each foam series were considerably improved with increasing scCO2pressure during the foaming processes. The expansion ratios and cell densities of each scCO2aTPS100CNF0.02GAxfoam series were increased considerably to a maximum value, as the GA content approached an optimum value. The optimal scCO211TPS100CNF0.02GA1.6foam material exhibited a high expansion ratio and cell density at approximately 50 and approximately 8 × 108cells/cm3, respectively. Compared with corresponding aged scCO2aTPS and scCO2aTPS100CNF0.02foam specimens, considerably better moisture resistance and σcretention properties were observed for scCO2aTPS100CNF0.02GAxfoam specimens, when they were modified with the corresponding optimum GA content. The moisture resistance and σcretention for optimal prepared scCO27TPS100CNF0.02GA0.4, scCO29TPS100CNF0.02GA0.8and scCO211TPS100CNF0.02GA1.6foam materials improved further with increasing scCO2pressure. Possible reasons accounting for the highly expansion ratio, moisture resistance, and σcretention properties for scCO2aTPS100CNF0.02GAxfoams are presented.

Preparation and characterization of [H2-DABCO][ClO4]2 as a new member of DABCO-based ionic liquids for the synthesis of pyrimido[4,5-b]-quinoline and pyrimido[4,5-d]pyrimidine derivatives

[H2-DABCO][ClO4]2, as a novel DABCO-based ionic liquid, has been synthesized, characterized, and used as an affordable and recyclable catalyst in the synthesis of pyrimido [4,5-b]-quinoline and pyrimido [4,5-d]pyrimidine derivatives. The procedure shows several advantages over the previous methods such as simplicity, high yields, short reaction times, easy work-up, and use of a non-metal catalyst. Moreover, this paper virtually debates the impact of anions and cations on moisture-resistant property and catalytic activity in DABCO-based ionic liquids through the comparison of [DABCO](SO3H)2(Cl)2, [DABCO](SO3H)2(HSO4)2, [H2-DABCO][H2PO4]2, [H2-DABCO][HSO4]2, and [H2-DABCO][ClO4]2.