Hot Water Resistance Research Articles

Development of poly(vinyl acetate) adhesive with hot water resistance via constructing semi‐IPN/IPN structures with hydroxymethylated lignin

AbstractPoly(vinyl acetate) (PVAc) adhesive is often used in the wood industry because it can be rapidly cured at room temperature to produce a high bonding strength. However, PVAc is a linear polymer susceptible to thermal creep, so it will fail to bond in high temperature and humidity environments. In this study, the hot water resistance of PVAc adhesive is improved by introducing lignin with a complex structure to construct multiple cross‐linked networks with a high cross‐link. However, due to the large steric hindrance, the reactivity of lignin hydroxyl groups is low. In the process of preparing adhesive, alkali lignin is hydroxymethylated to improve its reactivity, and then 4,4′‐diphenylmethane diisocyanate is used as a cross‐linker to construct interpenetrating and semi‐interpenetrating polymer networks. The hydroxymethylation occurs through the reaction of formaldehyde with lignin under alkaline conditions. Optimal reaction conditions include a reaction ratio of 0.20, a reaction temperature of 80°C, and a reaction time of 3.5 h. On those conditions, the bonding strength of the lignin‐based PVAc adhesive reaches 1.8 MPa after hot‐water treatment. Therefore, the lignin‐based hot water‐resistant PVAc adhesive has shown good application potential in high temperature and humidity environments.

A novel poly(2-hydroxyethyl acrylamide) copolymer for the fabrication of transparent antifogging coatings on polycarbonate substrates

Although polycarbonate (PC) is widely used in various applications, its inherent hydrophobicity limits its potential in applications that require high light transmittance due to surface fog caused by changes in temperature or humidity in the environment. This work presents a facile method to fabricate transparent antifogging coatings on PC substrates based on poly(2-hydroxyethyl acrylamide-co-2-aminoethyl methacrylate) (P(HEAA-co-AEMA)), in which the AEMA segments have an amino functional group that can react with the ester group on the surface of the PC substrate to form covalent urethane bonds during the heat curing process, avoiding the problems of coating susceptibility to mechanical damage, ease of peeling, etc. Moreover, HEAA units are employed as hydrophilic groups, providing antifogging performance. These antifogging coatings can be easily obtained by coating P(HEAA-co-AEMA) copolymers on PC substrates at room temperature and then curing them by thermal treatment. These transparent coatings exhibited excellent antifogging and self-cleaning performance. Furthermore, the coatings exhibited good adhesion in the cross-cut test and thermal stability in the hot water resistance test. Therefore, the present P(HEAA-co-AEMA) copolymer coatings are promising for practical antifogging applications.

A mechanically durable slippery liquid-infused porous surface based on distinctive ‘jaboticaba-like’ TiO2/sepiolite nanocomposites with superior hot water repellency and anti-corrosion for protecting various substrates

Slippery liquid infused porous surfaces (SLIPS) are widely utilized due to their omniphobicity and distinctive slippery properties. Fragile mechanical properties and unstable lubricant layer of SLIPS have a substantial impact on its long-term application performance. Herein, a pre-oil-infused mechanically robust organic/inorganic composite superhydrophobic surface (SC) for SLIPS with hierarchical roughness was obtained by in-situ growing a significant amount TiO2 nanospheres on the surface of sepiolite (SEP) fiber structures via hydrogen bonding, Ti-O-Si covalent bonding, and electrostatic power, resulting in a unique bionic “jaboticaba-like” structure on SC. Through hydrogen bonding, the hydroxyl groups on the TiO2 surface can also interact with the cross-linked polymer PVDF-HFP (polyethylene fluoride hexafluoropropylene). In the presence of multiple interactions, SC could resist 300 cycles of a rigorous Taber rubbing test with a 500 g weight and yet retain superhydrophobicity. The prepared SLIPS have exceptional hot water (boiling water) resistance, strong shear stability (8000 rpm/min), and water jetting resistance (40 kPa). Corrosion current density of SLIPS and SC was decreased by roughly 4 orders of magnitude and 3 orders of magnitude, respectively, after exposure to 3.5 wt% NaCl solution as compared to bare aluminum substrate. SLIPS have higher long-term corrosion resistance compared to SC. Owing to the “jaboticaba-like” hierarchical structure, SLIPS have great oil-locking capabilities, as well as good mechanical stability and long-term corrosion resistance. This article offers recommendations for developing tough SLIPS for future engineering applications.

Fluorine-free and hot water repellent superhydrophobic palygorskite: A combined experimental and molecular dynamics study

The present work investigates the wettability of dodecyltrimethoxysilane (DTMS) functionalized palygorskite (PAL) using both experimental and molecular dynamics approaches. The best superhydrophobicity was achieved at a PAL/DTMS ratio of 0.60 g/mL. Changes in wettability were simulated by varying the DTMS grafting ratio from perspectives of contact angle, interaction energy, the water molecule’s distribution characteristics, and hydrogen bonds. The results show that DTMS grafting promotes hydrophobicity, whereas excess grafting ratio declines hydrophobicity due to roughness decrease. The hot water resistance was analyzed from interaction energy, diffusion behavior, and cohesion energy, and the findings are consistent with the experimental results.

Morphology and Selected Properties of Modified Potato Thermoplastic Starch

Potato thermoplastic starch (TPS) containing 1 wt.% of pure halloysite (HNT), glycerol-modified halloysite (G-HNT) or polyester plasticizer-modified halloysite (PP-HNT) was prepared by melt-extrusion. Halloysites were characterized by FTIR, SEM, TGA, and DSC. Interactions between TPS and halloysites were studied by FTIR, SEM, and DMTA. The Vicat softening temperature, tensile, and flexural properties were also determined. FTIR proved the interactions between halloysite and the organic compound as well as between starch, plasticizers and halloysites. Pure HNT had the best thermal stability, but PP-HNT showed better thermal stability than G-HNT. The addition of HNT and G-HNT improved the TPS's thermal stability, as evidenced by significantly higher T5%. Modified TPS showed higher a Vicat softening point, suggesting better hot water resistance. Halloysite improved TPS stiffness due to higher storage modulus. However, TPS/PP-HNT had the lowest stiffness, and TPS/HNT the highest. Halloysite increased Tα and lowered Tβ due to its simultaneous reinforcing and plasticizing effect. TPS/HNT showed an additional β-relaxation peak, suggesting the formation of a new crystalline phase. The mechanical properties of TPS were also improved in the presence of both pure and modified halloysites.

High temperature oil–water separation based on superwettable membranes for removing water from condensation reactions

A superhydrophobic porous glass membrane possessing hot water resistance was fabricated and used for efficient separation of water from oil under high temperatures. It was successfully adopted for the removal of water from condensation reactions.

Transparent and superhydrophilic antifogging coatings constructed by poly(N-hydroxyethyl acrylamide) composites

A simple and convenient strategy for fabricating superhydrophilic antifogging coatings was developed by poly(N-hydroxyethyl acrylamide) (PHEAA) composites enhanced by zwitterionic sulfobetaine silane (SBSi)-modified SiO2 nanoparticles. These antifogging coatings can be easily obtained by coating PHEAA composites on substrates at room temperature and then cured by thermal treatment. Such transparent coatings exhibited excellent antifogging performance under both hot and cold fogging conditions. Additionally, the coatings have good adhesion against the cross-cut test and thermal stability in the hot water resistance test. The present PHEAA composite coatings are promising for real-world antifogging applications.

Multilayered chitosan/kaolin@calcium carbonate composite films with excellent chemical and thermal stabilities for oil/water filtration realized by a facile layer-by-layer assembly

Herein, a novel separation mesh membrane with chitosan/kaolin@calcium carbonate (CS/KL@CaCO3) coating was fabricated via a facile and eco-friendly approach. Owing to the hierarchical micro/nano-structure and high hydrophilicity of the composite coating, the decorated membrane demonstrates outstanding superhydrophilicity in air and underwater anti-oil-fouling capability. The membrane can realize efficient separation to various light oil/water mixtures, and the separation efficiencies are >98.0%. Especially, there is no obvious change in the separation efficiency after the reuse of 80 cycles, suggesting its good recyclability. In addition, the membrane displays satisfactory corrosion resistance and hot water resistance, and is applicable for the removal of corrosive solutions or hot water in oils. The high separation efficiency, excellent oil-repelling capability underwater, and readily scaled-up fabrication procedure of the membrane suggest enormous application potential in dealing with oil spills and separating oily wastewater.

Adhesive performance of cottonseed protein modified by catechol-containing compounds

Cottonseed protein has been shown to have promising adhesive properties as an eco-friendly and effective polymeric wood adhesive. In this work, we adopted the biomimetic concept from mussel adhesion, where phenolic residues, particularly catechol-type of structures, have been found to contribute towards the adhesive behavior of the materials secreted by mussels. Thus, we chose catechol, gallic acid and caffeic acid as possible modifiers for cottonseed protein isolate (CPI) adhesives. At concentrations between 50 and 200 mM, the acids improved the dry adhesive performance of CPI by 18–40%. At a 50 mM concentration, gallic and caffeic acids showed 46 and 27% enhancements in hot water adhesive performance relative to CPI alone but only showed slight enhancements for the water soak of 7 and 12%, respectively. For CPI with 200 mM of gallic or caffeic acids, the hot-water resistance and soak tensile strength decreased relative to the CPI control. For all three adhesion tests, 50 mM catechol exhibited no statistical improvement over the CPI control. The corresponding evaluations with soy protein isolate (SPI) showed only marginal improvements in dry adhesive performance for gallic acid, caffeic acid, and catechol, each at 200 mM concentration. Through this work, two new promoters for CPI adhesion (gallic and caffeic acids) have been discovered. In addition, some mechanistic information concerning the adhesion of catechol-like structures has been obtained.

Green preparation of thermal and solvent resistant poly (tetrafluoroethylene‐co‐perfluoropropylvinyl ether) hollow fiber membrane for organic solvent recycling

AbstractSo far, the organic solvent recycling still has great challenges. Herein, the thermal and solvent resistant poly (tetrafluoroethylene‐co‐perfluoropropylvinyl ether) (PFA) hollow fiber membranes (TS‐PFA HFMs) were continuously designed by on‐line compound technique for organic solvent recycling. The experiment results indicated that the increased sintering temperature brought about the porous surface and loose internal cavity structures. Importantly, the membrane exhibited the excellent thermal resistance at 70°C working condition. Furthermore, part of the poly (vinyl alcohol) was retained in the membrane which was competent to create synergistic effects, and endowed the membrane with not only favorable elasticity but also remarkable hot water resistance. Finally, the excellent organic solvent recycling ability of the membrane was demonstrated in simulated non‐aqueous solvent dyeing system. Specifically, no organic solvents or other hazardous substances were used during the fabrication process, which can realize the green preparation of the membrane.

Preparation and evaluation of catfish protein as a wood adhesive

In order to decrease the usage of formaldehyde and petroleum-derived raw materials, there has been a lot of interest in using protein-based wood adhesives as more eco-friendly and less hazardous alternatives. Fish proteins can be extracted from fish and are known to have good adhesive properties. In this work, we extracted the protein from catfish skin and characterized its effectiveness as a wood adhesive. Upon analysis, this protein from catfish skin (a byproduct of catfish processing) performed well as an adhesive, with similar (or slightly better) dry adhesive strength relative to cottonseed protein isolate. The blend of catfish protein and cottonseed protein displayed about the same dry adhesive strength when compared to catfish protein alone. The hot water resistance of catfish protein and cottonseed protein was comparable, but the 1:1 blend exhibited improved performance than the two proteins by themselves. These results suggest that the protein from catfish skin may be a suitable material for wood adhesive applications.

Features of the Technology of Construction of Road Pavements from Vacuum-Treated Asphalt Concrete Mix

When changing the structural properties of road construction materials, their compaction technologies should be improved with the choice of the best compaction means and their technological modes of operation in specific conditions of work conduction. For a mixture evacuated at an asphalt concrete plant that has increased water and frost resistance characteristics, as well as changed rheological parameters, it is also necessary to determine the technological parameters of the compaction means used, taking into account the features of its rheological characteristics. The compaction technology of vacuum-treated hot asphalt-concrete mix by pneumatic wheel roller with the determination of the necessary number of passes on the trail, speed modes along the roller passages and the magnitude of the air pressure in the tires of the roller has been developed. Using a promising rheological approach, the dynamics of accumulation of the asphalt concrete mixture layer density along the roller passages was studied by simulation modeling, and the time when the pneumatic roller was finished and the compaction work was transferred to heavy smooth rollers was determined. Changing the rheological properties of the vacuum-treated asphalt mix increases the efficiency of its compaction, reducing material costs, increasing the productivity of compaction tools while improving the quality and durability of road asphalt pavements. Keywords: hot asphalt-concrete mix, rheological properties, water and frost resistance of asphalt concrete, road roller, compaction.

The usage of novel acrylic-modified water-reducible alkyd resin obtained from post-consumer PET bottles in water-based paint formulation

Glycolysis reactions of waste polyethylene terephthalate (PET) flakes obtained from post-consumer water bottles were carried out at 220–250 °C using diethylene glycol, dipropylene glycol and triethylene glycol, and molar ratios of PET/glycol in the glycolysis reactions were chosen to be 1/3. The obtained glycolysis products were used in the synthesis of medium-oil acrylic-modified water-reducible alkyd resins. Acrylic modification was carried out using methacrylic acid–maleic acid copolymer synthesized in our laboratory. The structure of the acrylic copolymer was investigated with FTIR analysis. Films of the modified alkyd resins were prepared and their physical and chemical surface coating properties were investigated. When surface coating test results were evaluated, it was observed that waste PET had no adverse effect on these properties of acrylic-modified water-reducible alkyd resins. Then, two water-based paints were prepared using PET-based acrylic-modified water-reducible alkyd resin and reference acrylic-modified water-reducible alkyd resin as binder. Wet paint properties and physical/chemical dry film properties of paints were determined. When the physical surface coating test results were evaluated, no difference was observed between the properties of both paints. If we evaluate the results of chemical surface coating properties, the hot water and alkali resistance of waste PET-based paint was considerably higher than the reference resin.

Durable Lubricant-Impregnated Surfaces for Water Collection under Extremely Severe Working Conditions.

It is worth noting that the multifunctional surfaces are highly desirable for water collection applications on droplet nucleation and removal. Although the superhydrophobic surfaces is beneficial to water collection due to easily shed liquid drops and favorable heat-transfer performance, the pinned condensed water droplets within the rough structure and a high thermodynamic energy barrier for nucleation severely limit the water collection efficiency. Recently, the liquid-infused surfaces have been significant for condensation heat transfer and droplet nucleation but have poor durability. In this work, under the UV light, polydimethylsiloxane was grafted onto ZnO nanorods (through Zn-O-Si bond), and the residual unbonded silicone oil was used as the lubricant, so that it form a hierarchical lubricant-impregnated surfaces. Because of high viscosity of silicone oil and strong intermolecular force between silicone oil and PDMS brush, the lubricant can be firmly fixed in micronanostructure to form a durable lubricant layer. For example, the LISs have outstanding properties such as boiling water repellency, omniphobicity of various liquid, and hot water resistance. Under a self-made hot vapor collection device, the surface can maintain good water collection capacity and there is no obvious change in the lubrication layer. After exposing in sunlight for 7 days and subjecting them to 25 times heating/cooling cycles (heating at 150 °C), the LISs exhibit excellent water collection and repairability. After measurement, the oil content in the water is 43 mg/L, which is harmless to the human body. Through the high-water collection efficiency and durable lubricant layer, the LISs can be applied on a large scale in the water collection industry.

Cottonseed protein-based wood adhesive reinforced with nanocellulose

Although protein-based adhesives are eco-friendly, sustainable, and biodegradable, continued improvement in their adhesive performance is desirable. In this work, the effect of adding nanocellulose particles to cottonseed protein-based wood adhesives was studied. Cellulose nanofibers (CNF) were found to be most beneficial at about a 2% additive level, giving 22% improvement in dry adhesive strength over the cottonseed protein control. Cellulose nanocrystals (CNC) were optimal at about 10% additive level, giving 16% strength improvement relative to cottonseed protein alone. The hot water resistance of cottonseed protein isolate was also improved with CNF addition, but not with CNC addition. For comparison, soy protein isolate was also studied and showed about the same relative dry strength improvements with nanocellulose addition, but improvement of hot water resistance was less apparent. Infrared and thermogravimetric analysis suggested that the protein and the nanocellulose were interacting with each other. Thus, CNF may be a useful additive to cottonseed protein formulations used as wood adhesives.

Evaluation of adhesion properties of blends of cottonseed protein and anionic water-soluble polymers

There is increasing interest in agro-based, biodegradable and eco-friendly wood adhesives as partial replacements for petroleum-based adhesives. In this work, we studied the adhesion of cottonseed protein isolate (CPI) blended with several anionic water-soluble polymers. Anionic vinyl polymers studied included poly(acrylate), poly(acrylate-co-acrylamide), poly(vinyl sulfate), poly(vinyl sulfonate), and poly(vinyl phosphonate). Anionic polysaccharides studied included three types of carrageenan, carboxymethyl cellulose (CMC), low-methoxy pectin, alginate, and chondroitin sulfate. In general, the adhesive strength of CPI increased with the addition of anionic polymer up to a certain level and then decreased with further polymer addition. Different anionic polymers showed different enhancements. The best result for vinyl polymers was observed for the CPI/poly(vinyl sulfate) blend, which exhibited a 30% improved dry strength over CPI alone. The best results for the polysaccharides were obtained for the CPI/CMC and CPI/pectin blends, with improvements in dry adhesive strength over the CPI control of 66% and 50%, respectively. The CPI/CMC and CPI/pectin blends also showed improved hot water resistance. These findings suggest that the CPI/anionic polymer blends might be useful components in biobased wood adhesive formulations.

Dual-Bioinspired Design for Constructing Membranes with Superhydrophobicity for Direct Contact Membrane Distillation.

Water flux and durability are the two critical parameters that are closely associated with the practical application of membrane distillation (MD). Herein, we report a facile approach to fabricate superhydrophobic polyimide nanofibrous membranes (PI NFMs) with hierarchical structures, interconnected pores, and high porosity, which was derived from the electrospinning, dual-bioinspired design, and fluorination processes. Bioinspired adhesive based on polydopamine /polyethylenimine (PDA/PEI) composite was first linked onto membrane substrates and then assembled lotus leaf hierarchical structure by binding the negatively charged silica nanoparticles (SiO2 NPs) via electrostatic attraction. The resultant superhydrophobic PI NFMs exhibit a water contact angle of 152°, robust hot water resistance of 85 °C, and high water entry pressure of 42 kPa. Moreover, the membrane with omniphobicity presents high water flux over 31 L m-2 h-1 and high salts rejection of ∼100% as well as robust durability for treating high salinity wastewater containing typical low surface tension and dissolved contaminants (Δ T = 40 °C). Significantly, the novel dual-bioinspired method can be used as a universal tool to modify various materials with hierarchical structures, which is expected to provide more effective alternative membranes for MD and even for other selective wetting separation fields.

Wood adhesive properties of cottonseed protein with denaturant additives

Most commercial wood adhesive use either formaldehyde-based resins or polyurethanes, both of which include potentially toxic chemicals in their formulations. As a result, proteins are being considered as greener and more sustainable wood adhesives. While most of the protein adhesive studies focus on soy proteins, there is also interest in exploring alternatives. In this work, testing of the adhesive performance of cottonseed protein isolate was undertaken in the presence of protein denaturants, i.e. guanidine hydrochloride (GuHCl), sodium dodecyl sulfonate (SDS), urea, and alkali. For comparison, soy protein isolate was also included in the study. At optimal dosage levels, the dry adhesive strength of cottonseed protein isolate could be enhanced by 38, 25, or 47% with SDS, GuHCl, or urea, respectively. The dry adhesive strength and hot water resistance of cottonseed protein isolate was generally superior to that of soy protein isolate, with or without the denaturants. Thus, the combination of cottonseed protein with an optimal concentration of a denaturant may be a potentially promising polymeric system for use as wood adhesives.

Effects of phosphorus-containing additives on soy and cottonseed protein as wood adhesives

Soy and cottonseed proteins appear promising as sustainable and environment-friendly wood adhesives. Because of their higher cost relative to formaldehyde-based adhesives, improvement in the adhesive performance of proteins is needed. In this work, we evaluated the adhesive properties of soy and cottonseed protein formulations that included phosphorus-containing acids and esters. For cottonseed protein isolate, most of these additives improved dry adhesive strength, with methylphosphonic acid, phosphorous acid, and phosphoric acid increasing the dry strength by 47, 44, and 42%, respectively, at their optimal concentrations. For soy protein isolate, these additives did not show significant benefits. The phosphorus-containing additives also improved the hot water resistance of the cottonseed protein formulations but showed either no effect or a negative effect for the of soy protein formulations. Thus, the combination of cottonseed protein with phosphorus additives appears to be attractive as wood adhesives.

Decorating wood flour/HDPE composites with wood veneers

The low surface free energy makes wood plastic composites difficult to bond with traditional adhesives, such as urea formaldehyde resin (UF). This study investigates the decoration of wood flour/high‐density‐polyethylene composite (WF/HDPE) board with poplar wood veneers. High‐density polyethylene (HDPE) or maleic anhydride grafted polyethylene (MAPE) film was introduced between the veneer and the WF/HDPE composite board as an intermediate component to strengthen the bond. Surface bonding strength, hot water resistance, and bending performance of the composites were then evaluated. Contact angle, Attenuated total reflection‐Fourier transform infrared (ATR‐FTIR) spectroscopy, and scanning electron microscopy (SEM) were used to analyze the interface of the wood veneer and the WF/HDPE composites. The addition of MAPE film enhanced the polar characteristic of the WF/HDPE composite surface and increased the number of functional groups reacting with the –OH groups present in the wood veneer. A MAPE intermediate film increased the surface bonding strength of the wood veneer to WF/HDPE composite surface, and also endured boiling water without delimitation failure. After being covered with the wood veneer, the flexural strength and modulus of WF/HDPE composite panels increased four times comparing to that of the uncovered composites. POLYM. COMPOS., 39:1144–1151, 2018. © 2016 Society of Plastics Engineers