Water Absorption Resistance Research Articles

A strategy for dual-networked epoxy composite systems toward high cross-linking density and solid interfacial adhesion

Epoxy composites (ECs) are used as epoxy molding compound (EMC), which significantly protects the integrated circuits from the humid environment. One of the major limitations with ECs is their phenomena of moisture absorption in humid environments, which drastically reduces their mechanical properties and hinders them from gaining widespread industrial applications. The low cross-linking density of conventional epoxy composites that can lead to intrinsically providing hydrophilic sites and low activation energy in water molecule diffusion. Herein, a dual-networked epoxy composite system as a platform technique by adopting strategically designed poly (methyl methacrylate)-b-(dimethyl aminoethyl methacrylate) (PMD) as polymer compatibilizer to improve the water absorption resistance and mechanical properties derived from good interfacial adhesion and high cross-linking density of epoxy/silica composites were investigated. The as-prepared dual-networked epoxy composite system demonstrates a high-water absorption suppression of about 166.78% and a high tensile modulus of 4.6 GPa, compared to other epoxy composites. In addition, the current strategy has excellent expandability to various fillers also applicable to diverse epoxy composite systems.

Comparative Study of Cement Replacement with Waste Plastic in Interlocking Paving Stone for Highway Construction in Nigeria

Portland cement remains the major binder used in the construction of concrete pavements, interlocking stones, and many other aspects of construction, and this implies a high dependence on the commodity thus making it scares and expensive and hence the need to explore other alternatives. This research compares the use of waste plastics and Portland cement for the production of paving stones. In this study, three cases were considered, each case having a study sample and a control sample. Case 1, case 2, and case 3 had mix ratios of (in order of, binder to sand to granite) 1:1:1, 1:1:1.5, and 1:1.5:2.5 respectively, of which the controls were made using Portland cement as the binder and the samples were made with waste plastic as the binder. The comparison was done using compressive strength and water absorption resistance values of the controls and the sample. The results showed that paving stones made from Portland cement have better compressive strength in all cases compared to the samples, the highest compressive strength obtained from the controls was 45N/mm2 while that of the sample was 25N/mm2, however, the study sample showed the highest water absorption resistance percentage of 5%, when compared to the control samples which had as low as 0.8%. This infers that paving stones made from melted waste plastics may not be as strong as those made from Portland cement can be used for roads expected to carry lighter traffic, and are also very suitable for areas of high water table or areas prone to flooding. The samples in this research were made locally and were limited to the three mix ratios mentioned. Further research can be done using a mechanized method to produce the samples, also partial replacement of cement with waste plastic may hence the strength of the paving stone.

Review paper: properties of low molecular weight phenol formaldehyde – treated bamboo composite

Impregnation of bamboo in phenol formaldehyde (PF) solution is one of the promising solutions to overcome the drawback of the material. The use of low molecular weight PF resin (LMW PF) in the production of bamboo composite materials not only improves the dimensional stability but also increases the mechanical strength of the material. The bonding interface between bamboo elements and adhesives is presumed to be significantly influenced by the degree of adhesive penetration into the porous network of interconnected cells of bamboo surfaces. The permeation of PF resins in bamboo is closely related to their molecular weight. LMW PF resin will overpenetrate and lead to an undesirable starved bondline while high-MW PF resins only remain in the bondline and it is difficult to form mechanical interlocking. This paper discusses the research results on the bonding quality of bamboo strips when impregnated in LMW PF solution with different ratios and different pressing technology parameters; at the same time, physical and mechanical properties of bamboo composite materials treated with PF PTLT such as: water absorption resistance, dimensional stability, bonding strength, modulus of rupture (MOR), modulus of elasticity (MOE) are also significantly improved. This is a scientific basis that can serve as a premise for the research on technology to produce composite materials from bamboo and LMW PF in Vietnam.

Effects of acidity, number of hydroxyl group, and carbon chain length of carboxylic acids on starch cross-linking

Corn starch film samples cross-linked using malic, malonic, and succinic acids, and thermoplastic starch were characterized and tested for their water absorption, surface morphology, structural change, and thermomechanical properties. The acids vary in acidity, number of hydroxyl groups, and carbon chain length. The presence of an additional hydroxyl group has helped malic acid form more hydrogen bonding between starch molecules. The relatively higher acidity in malic acid compared to succinic acid is found to be another factor for its better cross-linking potential. The additional carbon chain in succinic acid, which reduces its solubility and acidity; has negatively affected its cross-linking potential. Among the three variables studied, number of hydroxyl group has highly influenced the cross-linking potential, followed by acidity and carbon chain length, respectively. Consequently, the elongation at break and water absorption resistance of thermoplastic starch were improved from 108.63 ​MPa to 175.72 ​MPa and from 140% to 80%, respectively, cross-linking corn starch with malic acid.

Enhancing the Mechanical Properties of Waterborne Polyurethane Paint by Graphene Oxide for Wood Products.

Water-based polyurethane paint is widely used for wood furniture by virtue of the eco-friendliness, rich gloss, and flexible tailorability of its mechanical properties. However, its low solution (water or alcohol) resistance and poor hardness and wear resistance limit its application. The emerging graphene oxide has a high specific surface area and abundant functional groups with excellent mechanical properties, endowing it with great potential to modify waterborne polyurethane as a nanofiller. In this study, graphene oxide prepared by Hummers' method is introduced in the chemosynthetic waterborne polyurethane through physical blending. The testing results demonstrate that the appropriate usage of graphene oxide at 0.1 wt% could obviously improve water absorption resistance and alcohol resistance, significantly enhancing the mechanical properties of waterborne polyurethane paint. The corresponding tensile strength, abrasion resistance, and pendulum hardness of the graphene oxide-modified paint film increase by 62.23%, 14.76%, and 12.7%, respectively, compared with the pristine paint film. Meanwhile, the composite paint film containing graphene oxide possesses superiority, including gloss, abrasion resistance, pendulum hardness, and tensile strength in contrast with the commercial paint. The use of graphene oxide to enhance the waterborne polyurethane possesses strong operability and practical value, and could provide useful reference for the modification of waterborne wood paint.

A Review of the Durability-Related Features of Waste Tyre Rubber as a Partial Substitute for Natural Aggregate in Concrete

As the number of discarded tyres continues to increase, causing serious environmental problems, the need of recycling the waste tyre rubber become extremely urgent in worldwide. Today, there is an increasing focus on recyclable materials. The reuse of waste tyre rubber in concrete contributes to sustainable development. In the past 10 years, numerous experiments on the recovery of rubber from waste tyres to produce concrete products have been conducted. In this review, we conclude the major achievement of rubberized concrete (RC) durability, discuss and analyse the influence of rubber replacement rates, replacement patterns, particle size and treatment methods. Results show that an increase in rubber content can improve the chloride penetration resistance, acid and sulphate attack resistance, freeze–thaw resistance, and alkali–silica reaction damage resistance of concrete, and the content of 5–20% has a significant improvement effect. Rubber replacing fine aggregate is the best scheme for durability, followed by cement and coarse aggregate. In addition, the recommended rubber particle size is 0–3 mm. However, the rubber particle has adverse effects on abrasion resistance, impermeability, water absorption resistance and carbonation resistance. The pre-treatment of rubber or the addition of supplementary cementitious materials are effective and viable ways of improving the durability of RC. Further research is needed on the long-term durability of RC, as well as on ductility, energy absorption, and thermal and corrosion resistance.

Effects of Poly(vinylchloride)-Maleic Anhydride as Coupling Agent on Mechanical, Water Absorption, and Morphological Properties of Eggshell Powder Filled Recycled High Density Polyethylene/Ethylene Vinyl Acetate Composites

The recycled high density polyethylene (rHDPE)/ethylene vinyl acetate (EVA)/ eggshell composites using poly(vinylchloride)-maleic anhydride (PVC-MA) as coupling agent was compounded using Brabender internal mixer. The results showed that the compatibilization of rHDPE/EVA blends was enhanced by the addition of 6 phr of PVC-MA. Furthermore, the tensile, water absorption resistance, and interfacial adhesion properties were studied. Tensile properties such as tensile strength and Young’s modulus were improved, while the elongation at break was reduced by the addition of PVC-MA. The water absorption resistance was improved upon PVC-MA addition to the composites.

Reusing recycled powder as eco-friendly binder for sustainable GGBS-based geopolymer considering the effects of recycled powder type and replacement rate

Utilizing recycled powder (RP) as binder for geopolymer reduces the construction waste and contributes to the development of sustainable geopolymer materials, but the effects of RP type and replacing rate on the characterization of sustainable geopolymer with RP received less consideration in previous investigations. Therefore, this investigation showed the upcycling of various RPs as an eco-friendly binder for sustainable GGBS-based geopolymer, and the micro-characteristics, mechanical strength and transport performance of geopolymer containing RP up to 100% were measured. The results indicated that RP from various construction waste mainly consisted of hydrated products, un-hydrated cement particle, quartz and calcite. Incorporating high-volume RP enlarged the pore structure of GGBS-based geopolymer, and substituting RP for 100% GGBS resulted in relatively loose micro-structure of sustainable geopolymer. Incorporating RP decreased the autogenous shrinkage of GGBS-based geopolymer, but the mix of high-volume RP increased the drying shrinkage of GGBS-based geopolymer. The mechanical strength and resistance to water ingress of GGBS-based geopolymer decreased as the RP replacing rate was increased, and substituting RP for 100% GGBS led to a significant reduction of mechanical strength and water absorption resistance. However, the mechanical strength of geopolymer with 100% RP from hardened cement paste waste was much better relative to geopolymer with 100% RP from mortar waste or concrete waste, because hydrated cement particle in RP has relatively high polymerization activity. Optimizing RP type and replacing rate can prepare sustainable geopolymer with good performance, and the upcycling of 100% RP for fully recycled geopolymer is feasible and sustainable.

Properties of green mortar blended with waste concrete-brick powder at various components, replacement ratios and particle sizes

Concrete and brick waste sourced from construction waste are commonly mixed together, and grinding such concrete and brick waste mixtures directly into waste concrete-brick powder (WCBP) as an alternative binder is sustainable and promising. This study investigated the micro- and macro-properties of green mortar containing various WCBPs. The results show that WCBP consisting of waste concrete powder and waste brick powder has certain pozzolanic activity and good filler effect in new cement-based materials, and the waste brick powder has superior activity to the waste concrete powder in WCBP. The mix of WCBP decreases the fluidity and prolongs the setting time of fresh mixture. Incorporating waste brick powder refines the pore size of paste, but the mixed waste concrete powder enlarges the pore size of paste; moreover, the pore size of paste with fine particle WCBP is superior to that of paste with coarse particle WCBP. The mechanical strength and water absorption resistance of mortar generally decreases with WCBP addition, and there exists a linear relationship between the WCBP replacement level and strength of WCBP mortar. At the fixed WCBP replacement ratio, the mechanical strength and water absorption resistance of WCBP mortar are improved as the proportion of waste brick powder content in WCBP increases. Particularly, decreasing the particle size of WCBP improves the mechanical strength and water absorption resistance of WCBP mortar. Optimizing the WCBP component, replacement ratio and particle size can prepare WCBP mortar with satisfactory properties.

Facile Fabrication of Cellulose Nanofibrils/Chitosan Beads as the Potential pH-Sensitive Drug Carriers.

It is highly desirable to develop a safe, highly efficient, and biodegradable drug carrier with an enhanced drug transport efficiency. Cellulose nanofibrils (CNF) and chitosan (CS) composite hydrogels are promising candidate carriers with biological compatibility and non-cytotoxicity. Herein, the CNF/CS composite beads were prepared by dissolving cellulose and CS in LiBr molten salt hydrate and regenerating in ethanol. This preparation method is facile and efficient, and the obtained porous CNF/CS beads with the weight ratio of 8:2 exhibited a large specific surface area, uniform micro-nano-sized pores, strong mechanical property, and water absorption-resistance. Moreover, these beads as drug (tetracycline hydrochloride, TH) carriers showed a higher encapsulation efficiency (47.4%) at the TH concentration of 5 mg/mL in 24 h, and a higher drug loading rate (12.0%) than pure CNF and other CNF/CS beads prepared with different ratios. In addition, the TH releasing behavior of CNF/CS (8:2) beads fitted well into the zero-order, first-order, and Higuchi models under an acid condition, indicating that the drug release of these pH-sensitive beads was mainly affected by drug concentration under an acid condition. Therefore, these CNF/CS beads have great potential to be used as drug carriers for medical applications.

Application of silica fume in high-volume fly ash self-compacting recycled aggregate concrete

ABSTRACT Recent advancement in construction practices demands the utilisation of construction materials in a sustainable way which promotes the use of industrial by-products as Supplementary Cementitious Materials (SCMs) and alternative aggregates to protect diminishing natural resources. The present study proposed the utilisation of high-volume fly ash in the production of Self-Compacting Concrete (SCC) made with varying proportions of coarse and fine recycled aggregates. Natural Aggregates (NA) of both coarse and fine type in high-volume fly ash SCC were replaced with the respective type of recycled aggregates at the dosage of 0%, 50% and 100% by volume and their hardened state behaviour was studied in terms of compressive strength, chloride ion permeability, initial rate of water absorption, sorptivity coefficient and sulphate resistance. Results of the investigation recommends uses of Silica Fume (SF) at 10% dosages in ternary blends of cement along with high-volume fly ash for the production of SCC at 50% replacement level of both coarse and fine recycled aggregates, without compromising the hardened state properties of concrete.

WATER ABSORPTION AND WATER RESISTANCE OF POLYIZOL-M WATERPROOFING MATERIAL

WATER ABSORPTION AND WATER RESISTANCE OF POLYIZOL-M WATERPROOFING MATERIAL

A New Mixture Criterion for the Improvement of the Compressive Strength of Adobe Using Zeolite as Stabilizer

The use of zeolite as a stabilizer for adobe has proven to have the ability to improve its physical and chemical properties. This is shown in the positive results in terms of strength gain and water absorption resistance in adobe blocks. In this work, an investigation was carried out to evaluate the use of zeolite as adobe stabilizer. The adobes were made with two different types of soil with different content of zeolite (5, 10, 15, 20% by weight) maintaining the zeolite-lime ratio 1:1. The samples were tested on compressive strength and water absorption. The deterioration of the adobes was analyzed under conditions of extreme humidity. The results of this study revealed that adobe behavior is influenced by the synergistic relationship between soil, zeolite and lime, showing significant changes in compressive strength even under extreme humidity conditions. It was also observed that the chemical composition of the soil influenced the development of the pozzolanic reaction. The stabilization of adobes with 15% of zeolite showed the best mechanical behavior, before and after deterioration assay. Hence, zeolite promises to be a good alternative as a stabilizer in adobe construction systems.

Slow Release and Water Retention Performance of Poly(acrylic acid-co-acrylamide)/Fulvic Acid/Oil Shale Semicoke Superabsorbent Composites.

In order to achieve the low cost and multifunction of superabsorbent composites, poly(acrylic acid-co-acrylamide)/fulvic acid/oil shale semicoke (PAMFS) were prepared by free radical copolymerization of fulvic acid (FA), oil shale semicoke (OSSC), acrylic acid (AA) and acrylamide (AM). The characterization results revealed that FA and OSSC were involved in the construction of a three-dimensional (3D) polymeric network via hydrogen bonding and covalent bonding. The water absorbency of PAMFS in distilled water and 0.9 wt% NaCl solution were 724 and 98 g/g, respectively. The FA slow release of PAMFS in distilled water and soil was achieved due to the interaction between FA and the functional groups of polymer matrix by hydrogen bonds and covalent bonds. Furthermore, the potted experiment indicated that the addition of PAMFS to soil can significantly promote plant growth compared with the pure soil, regardless of water stress. Therefore, this superabsorbent composite showed an excellent water absorption and salt resistance performance, as well as nice slow release performance. It has a broad application prospect.

Experimental Studies on the Performance of Graphene Oxide Based Hybrid Nanopolymers for Bearing Applications

In this experimental study, graphene oxide-blended glass-filled nylon (GO-GFN) hybrid nanopolymer composites were developed and characterized. Transmission electron microscopic studies were performed to study the dispersion of graphene oxide in glass-filled nylon composites. Dynamic mechanical analysis and thermogravimetric analyses were conducted on the fabricated hybrid nanopolymer composites to analyze the mechanical and thermal stability. Mechanical properties were investigated by tensile test. The test showed improvements in young’s modulus and tensile strength. Water absorption test was conducted to study the water absorption resistance of the hybrid nanopolymer composites. Finally, roller bearings with graphene oxide and glass-filled nylon were fabricated and analyzed for wear under varying load and speed conditions in the test rig developed in-house. The tests proved the suitability of deploying hybrid nanopolymer composites for bearing applications.

PENGUJIAN SISTEM TOREFAKSI KAYU JATI MENGGUNAKAN MICROWAVE

Torrefaction is a heat treatment of raw biomass to obtain a fuel that is more stable, has a high energy density and higher brittleness and is easy to grind. The purpose of this study is to determine changes in physical properties, calorific value of water absorption resistance (hydrophobic) in teak wood after the torrefaction process in the microwave. The method used in this study is an experimental method using a microwave heater equipped with measuring instruments such as a digital thermometer, and digital scales. The biomass material used was finished wood cut with sample sizes of Model 1 (cube 3 x 3 cm), Model 2 (rectangular 7 x 3 x 3 cm), and Model 3 (cylindrical tube 7 x 3 cm). Each material was put in a microwave depth for torrefaction for 15, 25, 35 minutes. The results showed that the model 2 sample experienced the largest mass change of 80.95%, followed by model 3 with a mass change of 76.47% and Model 1 which experienced a mass change of 70%. The longer you experience electromagnetic wave radiation in the microwave, the greater the mass change and the lower the water absorption Keywords: Torrefaction, teak wood, microwave, calorific value, moisture content

Modified Waterborne Polyacrylate for Cotton Fiber Printing Development of prepolymer

Abstract In this paper, polyacrylate (PA) was modified by waterborne polyurethane (WPU) to synthesize waterborne polyurethane-acrylate coating material. The structural changes of each component before and after modification, emulsion performance, film performance and printing performance were studied. The effects of raw material ratio and process conditions on application performance of printing emulsion were explored. The results showed that under the conditions of drying temperature and time of 150 °C and 3 min, the optimal formula was resin coating (WPU : PA=4 : 6), mixed solvent, deionized water and pigment content of 25 %, 15 %, 45 % and 15 %, respectively. The obtained emulsion was stable, the water absorption and solvent resistance of the film were good, and the rubbing fastness of printing could reach 4–5 grade. The structural analysis showed that the polyacrylate emulsion was synthesized, and the modified emulsion had the composite structure of WPU/PA.

Mechanical Properties and Water Absorption Capacity of Hybrid GFRP Composites.

Hybrid glass fibre reinforced polymer (GFRP) composites have been used for decades in various engineering applications. However, it has a drawback with its application in marine/flood environments due to a lack of water resistance and frail mechanical stability. Floods have been considered one of the most periodic hazards that could hit urban areas, due to climate change. The present paper aims to address this gap and to investigate the mechanical properties (tensile, compressive, and flexural strength) and water absorption capacity of hybrid GFRP composite comprising woven E-glass fabric and epoxy resin, various reinforcing materials (kenaf and coconut fibres), and various filler materials (fly ash, nano-silica, and calcium carbonate (CaCO3). The composites with 30 wt.% GFRP, 50 wt.% resin, 15 wt.% fly ash, 5 wt.% CaCO3, 10 wt.% GFRP, 60 wt.% resin, and 30 wt.% fly ash showed the lowest water absorption property of 0.45%. The results revealed that the GFRP composite reinforced kenaf fibres with nano-silica, fly ash, and CaCO3 improved the water absorption resistance. At the same time, GFRP reinforced the coconut fibres with fly ash, and kenaf fibres with CaCO3 showed no favourable impact on water absorption. The identification of a hybrid GFRP composite with various reinforcing materials and fillers would assist future developments with a more compatible, enhanced, and reliable water-resistant composite, specifically for structural applications in flood-prone areas.

Preparation and Properties of Inkjet Waterborne Coatings

As an environmentally friendly coating, waterborne coatings have broad application prospects in paper packaging products in food and medicine. In this paper, a waterborne coating is synthesized from epoxy resin, polypropylene glycol diglycidyl ether, acrylic acid, trimellitic anhydride, maleic anhydride, and organic amine by three steps: ring opening reaction, esterification reaction, and neutralization reaction. Using viscosity, particle size, thermal stability, adhesion, and friction resistance as performance evaluation factors, the effects of the ratios of epoxy resin and polypropylene glycol diglycidyl ether in the polymerization system on the performance of synthetic waterborne coatings were discussed. Taking water solubility, water absorption, and water resistance as performance evaluation factors, the effects of the amount of ratio of anhydride groups to hydroxyl groups in the epoxy acrylic resin, which were produced in the second step of the reaction, were considered on the performance of synthetic waterborne coatings. The experimental results showed that when the molar ratio of the epoxy group in the epoxy resin and polypropylene glycol diglycidyl ether was about 1:1, and the molar ratio of anhydride in maleic anhydride to hydroxyl in the epoxy acrylic resin generated in the second step of reaction was about 0.9:1, the performance of the prepared waterborne coatings was comprehensively better. At the same time, the applicability of self-made waterborne coatings was tested. The results showed that when the coating amount was about 3.60 g/m2, the properties of the packaging base paper were greatly improved with respect to air resistance, oxygen resistance, oil resistance, and color reproducibility.

Effect of Coal Bottom Ash as Partial Sand Replacement for Lightweight Aggregate Concrete

Environmental degradation due to disposal of waste namely coal bottom ash waste from thermal power plant, clinker waste of palm oil mill and river sand mining activity for concrete production need to be resolved. Palm oil clinker lightweight concrete with zero granite aggregate that been produced in effort to reduce dependency of natural stone consumption has been further explored its potential in this research. Thus, the present research investigates the compressive strength, water absorption and acid resistance of lightweight aggregate concrete containing coal bottom ash as partial sand replacement. Five types of concrete mixes were produced using 0%, 10%, 20%, 30% and 40% coal bottom ash as fine aggregate replacement. After curing process, specimens were immersed in acid hydrochloric solution before subjected to compressive strength testing. Findings show that all specimen experience strength reduction after exposed to acidic environment. On overall, the use of coal bottom ash influences the durability performance of lightweight aggregate concrete.