Moisture Absorption and Desorption in an Ionomer-Based Encapsulant:A Type of Self-Breathing Encapsulant for CIGS Thin-Film PV Modules

As an alternative to conventional encapsulation concepts for a double glass photovoltaic(PV)module,we introduce an innovative ionomer-based multi-layer encapsulant,by which the application of additional edge sealing to prevent moisture penetration is not required.The spontaneous moisture absorption and desorption of this encapsulant and its raw materials,poly(ethylene-co-acrylic acid)and an ionomer,are analyzed under different climatic conditions in this work.The relative air humidity is thermodynamically the driving force for these inverse processes and determines the corresponding equilibrium moisture content(EMC).Higher air humidity results in a larger EMC.The homogenization of the absorbed water molecules is a diffusion-controlled process,in which temperature plays a dominant role.Nevertheless,the diffusion coefficient at a higher temperature is still relatively low.Hence,under normal climatic conditions for the application of PV modules,we believe that the investigated ionomer-based encapsulant can“breathe”the humidity:During the day,when there is higher relative humidity,it“inhales”(absorbs)moisture and restrains it within the outer edge of the module;then at night,when there is a lower relative humidity,it“exhales”(desorbs)the moisture.In this way,the encapsulant protects the cell from moisture ingress.

Moisture Absorption, Mass Loss and Evaporative Resistance of Clothing in Transient Condition

The water vapour resistance of clothing ensembles is not as commonly determined as dry thermal insulation. The measurement techniques are more complicated and the measurement values differ among laboratories. Due to complicated moisture transfer process through clothing ensemble, the moisture absorbed and evaporated varies in transient and steady state phases depending on properties, thickness of clothing, and environmental conditions. The purpose of this study was to measure moisture gain inside hygroscopic underwear, and hydrophobic and permeable outer wear as a function of time, to investigate mass loss from ＂skin＂ as well as from the manikin, to quantify evaporative heat loss and total heat loss from the manikin, and to determine water vaponr resistance of clothing. Manikin Tore was used by wearing wet ＂skin＂ to simulate sweating condition. Moisture content in the inner garment gain shows an exponential relation against time. Moisture in the outer permeable layer shows little gain. On the contrary, mass loss directly from the wet skin decreases exponentially. The mass loss from the manikin is relatively stable throughout three test phases. The evaporative heat loss is about 2/3 of the total heat loss from the sweating manikin. While measuring the evaporative resistance of clothing ensembles with hygroscopic inner garment and permeable outer garment, unlike to measure ensembles with impermeable outer layer, one hour measurement time is enough to get relatively stable results. The variation between the 1^rt hour and the 3^nd hour is less than 5%. The length of transient period and measurement time is dependent on the permeability, thickness of clothing ensembles and environmental conditions.

Water Transport Models of Moisture Absorption and Sweat Discharge Yarns

An important property of moisture absorption and sweat discharge yarns is their water transport property. In the paper, two water transport models of moisture absorption and sweat discharge yarns were developed to investigate the influence factors on their wicking rate. In parallel Column Pores Model, wicking rate is determined by the equivalent capillary radius R and length of the capillary tube L. In Pellets Accumulation Model, wicking rate is decided by the capillary radius r and length of the fiber unit assemble L0.

Analysis of the Porosity Changing after Moisture Absorption in Functional Knitted Fabrics

The paper analyses the effect of stitch geometrical modality changing after moisture absorption on the porosity of knitted fabrics,and educes the formulas between porosity and stitch parameters.Regarding as the cell stitch,the increasing of yarn diameter brings the porosity decreasing and the fabric shrinking in the wale direction.While the diameter keeps invariability,the yarn elongating brings the fabric humping up as well as the increasing porosity.The air-permeability experiments have been conducted to validate the theoretical analysis,and there is reasonable agreement between the theories and experiments.

Moisture Absorption and Mechanical Properties of Chemically Modified Linen/Polypropylene Composites

To decrease the moisture absorption and improve the mechanical properties of linen/polypropylene（PP） composites, linen was modified with silane N-β-（trimethoxysilyl） propyl]ethylenediamine（AAPTS）, surfactant trimethyloctadecylalmnonium bromide（STAB）, and both AAPTS and STAB, respectively. Fourier transform infrared（FTIR） spectra showed that the linen was successfully modified and alkyl chains were attached through different treatments. The linen and PP were compounded by melt compressing. The moisture absorption of linen was decreased after STAB and AAPTS-STAB modifications. The moisture absorption, mechanical property and thermal property of the composites were also characterized. The results show that the moisture absorption of the AAPTS-modified li- nen（F1） reinforced PP（PPF1） is 8.09%, which is higher than that of the unmodified linen reinforced PP（PPF）（7.89%）. The moisture absorption of the STAB-AAPTS-modified linen（F3） reinforced PP（PPF3） is 6.58%. The tensile strengths of PPF1 and PPF3 are 33.7 and 35.8 MPa, which are improved by 22.5% and 30% compared with that of PPF（27.5 MPa）, respectively. Nevertheless, the moisture absorption of the STAB-modified linen（F2） reinforced PP（PPF2） is decreased by 22.4%, and the tensile strength is improved by 30% compared with those of PPF. Scanning electron microscopy（SEM） analysis of the fractured surface confirms the good interfacial adhesion of PPF2 compared with those of other composites. Furthermore, the 5% mass loss temperatures of the composites are all higher than 290 ℃. Thus, linen modified with STAB is a promising reinforcement for biocomposites.

Moisture absorption properties of biomimetic laminated boards made from cross-linking starch/maize stalk fiber

In the research,three kinds composite materials of biomimetic laminated boards made from cross-linking starch/maize stalk fiber-the single layer jute fiber reinforced maize stalk fiber boards,the dual layer jute fiber reinforced maize stalk fiber boards,the jute fiber hybrid reinforced maize stalk fiber boards were obtained according to the formulation of cross-linking maize starch adhesive and the preparation process of composite materials.The hygroscopicity variation of the biomimetic laminated boards made from cross-linking starch/maize stalk fiber was investigated under different relative humidity conditions.The moisture absorption rate and the variation velocity were used as important evaluation indexes to evaluate the moisture absorption properties of the straw fiber composites.The mathematical models of the moisture absorption rate and the variation velocity were established.The hygroscopicity variation curves of three kinds of composite materials were measured under the five different relative humidity conditions.The results showed that the three kinds composites had low moisture absorption rate compared with other stalk fiber composites which were good at water resistance and the waterproof property of the three kinds stalk fibers were excellent under the experimental conditions.The research provides a useful reference to improve the water resistance of fiber composites and a new idea on the development and application of the biodegradable composites,especially the straw fiber reinforced composites.

Water Absorption Capacity and Coating Adhesion on Thermally Modified and Not-Modified Spruce Wood(Blue Stained or Free of Blue Stained)

This study aimed to investigate the water absorption capacity of thermally modified and non-modified spruce and blue-stained spruce wood.The wettability of wood depends on various factors,including its type,density,porosity,and surface treatment.Wood can swell and become distorted when exposed to water or humidity,impacting its structural integrity.Hence,it is crucial to consider the water and water vapour uptake in the wood when choosing materials for applications that are likely to be exposed to moisture.Various moisture absorption tests were conducted to assess water absorption capacity,including short-term and long-term water absorption and water vapour absorption.The results showed a significant difference in the long-term exposure to water,which was related to the density of the wood.The study examined the influence of thermal treatment on the physical properties of wood and observed significant variations in mass change due to coating,indicating differences in adhesion among different wood types.Vacuum-treated blue-stained Norway spruce demonstrated higher adhesion(5%–15%)compared to air-treated samples.Furthermore,cohesion tests revealed lower cohesion force in blue-stained Norway spruce(approximately 20%–30%)compared to Norway spruce.The study also used industry-standard tests to investigate the adhesion and cohesion of nano-coatings on wood surfaces.The results provided valuable information on the properties of coatings applied to wood,which is vital in protecting and decorating wood while also providing preventive protection against wood pests,weathering,and mechanical influences.Wood modification in vacuum involves subjecting the wood to a low-pressure environment to remove air and moisture,allowing for deeper and more uniform penetration of treatment chemicals.In contrast,wood modification in air relies on the natural circulation of air to facilitate the absorption of chemical treatments,without the need for a vacuum chamber.

Effect of Accelerated Aging Temperature under Artificial Seawater on the Properties of Carbon Fiber/Epoxy Composites and the Erosion Mechanism

In order to explore the effect of artificial accelerated aging temperature on the performance of carbon fiber/epoxy resin composites,we used artificial seawater as the aging medium,designed the aging environment of seawater at different temperatures under normal pressure,and studied the aging behavior of carbon fiber/epoxy composites.The infrared spectroscopy results show that,with the increase of aging temperature,the degree of hydrolysis of the composite is greater.At the same time,after 250 days of aging of artificial seawater at regular temperature,40 and 60 ℃,the moisture absorption rates of composite materials were 0.45%,0.63%,and 1.05%,and the retention rates of interlaminar shear strength were 91%,78%,and 62%,respectively.It is shown that the temperature of the aging environment has a significant impact on the hygroscopic behavior and mechanical properties of the composite,that is,the higher the temperature,the faster the moisture absorption of the composite,and the faster the decay of the mechanical properties of the composite.

Damage degradation mechanism and macro-meso structural response of mudstone after water wetting

The predominant presence of weak interlayers primarily composed of mudstone renders them highly susceptible to a reduction in bearing capacity due to the water-rock weakening effect,significantly impacting the safety of open-pit mining operations.This study focuses on the weak mudstone layers within open-pit mine slopes.The mineral composition of mudstone and the microstructure evolution characteristics before and after water wetting were analyzed by X-ray diffraction(XRD)and scanning electron microscope(SEM).The meso-structure and parameter variation characteristics of mudstone interior space after water-rock interaction were quantified by computed tomography scanning test,and the damage variable characterization method was proposed.Additionally,according to the uniaxial compression test,the degradation characteristics of the macroscopic mechanical behavior of mudstone under different water wetting time were explored,and the elastic modulus and strength attenuation model of mudstone based on mesoscopic damage were established.Finally,building upon the macro-meso structural response characteristics of mudstone,an exploration of the failure characteristics and deterioration mechanism under the influence of water-rock interactions was undertaken.The results show that the water-rock interaction makes the internal defects of mudstone gradually develop and form a fracture network structure,which eventually leads to the deterioration of its macroscopic mechanical properties.The porosity,fractal dimension and damage characteristics of mudstone show an exponential trend with the increase of water wetting time.Moreover,the deterioration mechanism of mudstone after water wetting are postulated to encompass factors such as the hydrophilicity of mineral molecular structures,hydration stress and expansion effects on clay particles,as well as the spatial distribution of microcracks and the phenomenon of fracture adsorption.The outcomes of this research endeavor aim to provide certain reference value for further understanding the water-rock interaction and stability control of mudstone slope.

MOISTURE AND FLEXURAL BEHAVIOUR OF HEMP MAT FOAM STRUCTURAL INSULATED PANEL SPECIMENS

The use of structural insulated panels(SIPs)for wall and roof assemblies in residential and commercial buildings is a well-known construction technique.SIPs typically use a combination of either expanded polystyrene foam(EPS)or polyurethane foam(PUR)as the core material.The covering or skin is predominantly oriented strand board(OSB).The OSB is either bonded to the foam with adhesive in the case of EPS,while polyurethane is used to provide adhesion with PUR SIPs.This paper presents the results of research that investigated the use of industrial hemp mat used as a skin for soy-based polyurethane foam panels.A series of tests were conducted to investigate moisture resistance and flexural behaviour on hemp mat foam panels.Moisture absorption behaviour was evaluated on three specimen types:uncoated,earth plaster and tung oil treated hemp mat.The absorption coefficient Aw was determined for all specimens.The tung oil treated specimens exhibited a water absorption coefficient that was 5.3%of that for untreated hemp mat panel specimens.Flexural tests were conducted on dry specimens with earth-plastered hemp mat,tung oil coated hemp mat,OSB and,untreated hemp mat skins.Tung oil provided resistance to tension failure and increased capacity to withstand considerable deformation without tensile failure in flexural specimens.Compared with pure foam specimens,untreated hemp mat improved flexural performance by 16.3%.

Mechanical Properties Amelioration of Hybrid Composites by Concomitant Synergy Between Graphene Oxide and Silica Nanoparticles

Composite materials have attracted increasing attention to replace traditional materials such as metals for aerospace and automotive components due to their excellent mechanical and lightweight properties.By reinforcing with fillers,the material properties can be tailored to suit the needs of certain requirements.Nanofillers graphene oxide(GO) and silica(SiO_2) are incorporated into carbon fibre/epoxy(CF/E)composites to enhance epoxy resin properties by impregnating into the weak area of resin and boosting the interaction forces between resin and filler interfaces.The mechanical,thermal,and morphological properties of GO and SiO_2 fillers in the CF/E were investigated.Movever,after the exposure to distilled water and salt water,effect of moisture absorption on flexural and impact properties were investigated and the CF/E composite with hybrid nanofillers exhibited strong resistance to degradation in flexural and impact properties.FESEM images of the fracture surfaces indicated that the good performance of CF/E composite with bi-hybrid nanofillers originated from the synergistic GO and SiO_2 nanofillers,which limit the motion of epoxy polymer molecular chain and give sufficient stress transfer ability to the composite system.The overall results showed that GO and SiO_2 fillers can significantly enhance the mechanical properties as well as resistance to moisture environment.

Drying Technology and Formation Process of Naomai Xingshen Capsules

[Objectives]To optimize the drying technology and formation process of Naomai Xingshen Capsules.[Methods]The yield of paste powder and moisture content as evaluation indicators were taken as indicators,the relative density of feed liquid,inlet air temperature and dosage of excipients were selected as investigation factors,the orthogonal experiment method was used to optimize the spray drying process.The moisture absorption rate and angle of repose were taken as evaluation indicators,the types of forming excipient were screened,and the critical relative humidity was determined.[Results]The optimum spray drying process was that the relative density of liquid medicine was 1.05(60℃),the air inlet temperature was 200℃,and the dosage of excipients was 2%.The effect of using dextrin as a forming excipient was better,and the relative humidity of the production environment should be controlled below 65%.[Conclusions]The optimized process is stable,feasible,scientific and reasonable,and can be used for large-scale industrial production.

Experimental study on the influence of temperature and humidity on the thermal conductivity of building insulation materials

At present,thermal conductivity is usually taken as a constant value in the calculation of building energy con-sumption and load.However,in the actual use of building materials,they are exposed to the environment with continuously changing temperature and relative humidity.The thermal conductivity of materials will inevitably change with temperature and humidity,leading to deviations in the estimation of energy consumption in the building.Therefore,in this study,variations in the thermal conductivity of eight common building insulation materials(glass wool,rock wool,silica aerogel blanket,expanded polystyrene,extruded polystyrene,phenolic foam,foam ceramic and foam glass)with temperature(in the range of 20-60°C)and relative humidity(in the range of 0-100%)were studied by experimental methods.The results show that the thermal conductivity of these common building insulation materials increased approximately linearly with increasing temperature with maxi-mum growth rates from 3.9 to 22.7%in the examined temperature range.Due to the structural characteristics of materials,the increasing thermal conductivity of different materials varies depending on the relative humidity.The maximum growth rates of thermal conductivity with humidity ranged from 8.2 to 186.7%.In addition,the principles of selection of building insulation materials in different humidity regions were given.The research re-sults of this paper aim to provide basic data for the accurate value of thermal conductivity of building insulation materials and for the calculation of energy consumption.

Relative humidity and temperature dependence of mechanical degradation of natural fiber composites^(?)

In this paper,the mechanical degradation of natural fiber composites is studied with the consideration of the relative humidity and the temperature.A nonlinear constitutive model is established,which employs an internal variable to describe the mechanical degradation related to the energy dissipation during moisture absorption.The existing experimental researches demonstrated that the mechanical degradation is an irreversible thermodynamic process induced by the degradation of fibers and the damages of interfaces between fiber and matrix,both of which depend on the variation of the relative humidity or the temperature.The evolution of the mechanical degradation is obtained through the determination of dissipation rates as a function of the relative humidity and the temperature.The theoretically predicted mechanical degradations are compared with experimental results of sisal fiber reinforced composites subject to different relative humidity and temperatures,and a good agreement is found.