Preparation of polyHIPE/clay composites by using a reactive intercalant

Porous polymer composites have been synthesized by polymerizing the continuous phase of styrene/divinylbenzene high internal phase emulsions in the presence of organophilic montmorillonite clay having a novel oil‐based intercalant which is a reactive methacryl derivative of quaternized methyl oleate. The morphological features, thermal stability and mechanical properties, namely compression modulus and crush strength of the resulting composites have been investigated as a function of degree of nanoclay loading. All the composites reinforced with the clay were found to have improved thermal and mechanical properties as well as desired porous and interconnected structural morphology, as compared with the bare polyHIPE matrix. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41333.     

Properties and applications of nanoclay reinforced open‐porous polymer composites

Open‐porous nanoclay reinforced polymer composites were prepared via high internal phase emulsion templating using 1,3‐butanediol dimethacrylate and surface modified montmorillonite (SM‐MMT). Organophilic clay was obtained by using a reactive intercalant—quaternary cocoamine salt having a styryl group—for surface modification of MMT. The clay modification resulted in not only intercalated silicate layers but also nanoclay particles compatible with the continuous phase of the emulsions. It was found that increasing clay amount leads to formation of hierarchical porous structure accompanied with larger cavities and interconnected pores. In this respect, cavity size of the resulting composites was found to be altered between 6.78 and 8.82 μm. On the other hand, as compared to bare composites, addition of clay particles increased compressive modulus of the resulting materials from 26.4 to 72.5 MPa. The adsorption capacities of the porous composites for methyl violet 2B were investigated by batch experiments and discussed as a function of their SM‐MMT loading. It was determined that, the dye adsorption of the composites increased with increasing nanoclay amount in the polymer matrix. Thus, the adsorption percentage of the composite loaded with 7 wt % nanoclay was found to be as high as 88%. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45522.     

Sugar palm fiber/polyester nanocomposites: Influence of adding nanoclay fillers on thermal,dynamic mechanical,and physical properties

In this research, nanoclay used as filler in sugar palm‐reinforced composites was investigated by the physical, thermal, and dynamic mechanical properties. Various concentrations of nanoclay were used to fabricate composites by using hand lay‐up technique, followed by hot compression molding with naturally woven sugar palm fiber‐reinforced in polyester matrix. Among various weight concentrations such as 1–5% of nanoclay, it was found that 2% nanoclay‐filled composite (NC) demonstrated the best balance of thermomechanical properties and significantly enhanced the composite. DMA demonstrated that 2% nanoclay content resulted in improved viscoelastic behavior and higher glass transition temperature (T_g) of the composites. TGA also showed improvement in properties, whereas 3% nanoclay‐filled composite showed superior onset temperature, and 5% nanoclay‐filled composite exhibited highest remaining residue. The nanoclay filler was very effective to fill the porous structure and maintain the thickness stability. The thickness swelling was reduced with increasing amount of nanoclay in composites. Overall, the addition of nano clay improved thermal and physical properties of sugar palm‐reinforced polyester composite. J. VINYL ADDIT. TECHNOL., 26:236–243, 2020. © 2019 Society of Plastics Engineers     

Adsorptive polyHIPE composites based on biosorbent immobilized nanoclay: Effects of immobilization techniques

Styrene/divinyl benzene‐based macroporous polyHIPE composites were prepared from water‐in‐oil (w/o) high internal phase emulsion (HIPE) templates by using both organo‐modified montmorillonite (MMT) and a nonionic surfactant. For this purpose, Spirulina (Sp) microalgae was immobilized onto Na‐MMT clay by using two different modification techniques. They are based on conventional adsorption in solution (SOL) and novel cryoscopic expansion (C‐XP) assisted adsorption. Highly porous nanocomposites were prepared by using different percentages of modified nanoclays (SpSOLM/SpXPM) with a constant internal phase volume of 80%. The emulsion stability, morphology, and dye adsorption capacities were discussed by paying attention to nanoclay immobilization techniques, clay loading degree and surfactant concentration. The critical amount of nonionic surfactant for formation of the stable neat HIPE template was found to be only 5 vol% with respect to volume of organic phase. However, this amount was further reduced to much less value (2 vol%) with Sp immobilized nanoclays via help of cooperative interactions of Sp and MMT nanoclay. The C‐XP assisted modification of clay led to nanocomposites with 580% higher adsorption capacity for cationic dye. This remarkable benefit was obtained with even 0.5% clay loading and only 2% surfactant concentration. POLYM. ENG. SCI., 58:1229–1240, 2018. © 2017 Society of Plastics Engineers     

Influence of nanoparticles and antioxidants on mechanical properties of titania/polydicyclopentadiene polyHIPEs: A statistical approach

Open porous Pickering poly(high internal phase emulsion) composites were prepared by ring opening metathesis polymerization of surface modified TiO₂ nanoparticle stabilized dicyclopentadiene (DCPD) high internal phase emulsions. Oxidation of the double bonds in the polyDCPD chains of the resulting materials was prevented using antioxidants. Oxidation dependent variation of mechanical properties was demonstrated by applying compression tests to the resulting composite materials periodically. Periodical measurements revealed significantly reduced brittleness in the case of antioxidant containing polyHIPE composites. Furthermore, it was determined that the initial compression moduli and the compressive strengths of the resulting materials were significantly improved by using antioxidants as compared to antioxidant free samples. Moreover, increasing nanoparticle amount was found to have a beneficial effect with the presence of antioxidants. The relationship between the compression modulus with nanoparticle loading and different types of antioxidants was revealed by developing model regression equations and graphs. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 46913.     

Synthesis of flame retardant polyester‐urethanes and their applications in nanoclay composites and coatings

This paper describes the synthesis of phosphorus‐containing polyester‐urethanes and their applications in nanoclay composites and coatings. Polyester was prepared by the reaction of bis(bisphenol‐A) monophenyl phosphonate, maleic anhydride and phthalic anhydride. The polyester was reacted with various diols such as ethylene glycol, diethylene glycol and propylene glycol to obtain polyester polyols. Synthesized polyester polyols were characterized by chemical analysis and instrumental analysis and was used further to react with different isocyanates to develop polyester‐urethanes. The synthesized polyester‐urethanes were blended with organo‐modified montmorillonite nanoclay (1 wt%, 3 wt% and 5 wt%) and were cast in a mold and coated on mild steel panels. The thermal stability of neat polyester‐urethane and the nanoclay composites was determined by thermogravimetric analysis. The flame retardant properties of cast films and their composites were determined by the limiting oxygen index and UL‐94 test methods. The physical and mechanical properties of coatings such as pot life, drying properties, scratch hardness, pencil hardness, impact resistance, adhesion and flexibility were investigated. The chemical resistance properties of the coatings were also determined in different reagents. The data reveal that the polyester‐urethane nanoclay composites with 3 wt% clay hold promise for use in effective flame retardant coatings. © 2013 Society of Chemical Industry     

Synthesis of β-myrcene-based macroporous nanocomposite foams: Altering the morphological and mechanical properties by using organo-modified nanoclay

Organo-modified nanoclay incorporated high internal phase emulsions (HIPEs) were successfully used for the preparation of macroporous nanocomposite foams. Due to the aim of obtaining mechanically improved foams, HIPEs were prepared by using a monomer mixture composed of β-myrcene and ethylene glycol dimethacrylate. Accordingly, two groups of macroporous nanocomposite foams were synthesized depending on the nanoclay type. The morphological analysis demonstrated that the pore openness of the resulting nanocomposites were significantly improved due to the decrease in the average cavity size and increase in the interconnected pore size. In terms of mechanical properties, it was found that filling 1 wt% of nanoclay which is surface modified by hydrogenated tallow lead to a 33% of increment in the compression modulus, as compared to the neat foam. However, loading 5 wt% of nanoclay having octadecylamine and aminopropyltriethoxysilane surface groups caused only 11% of increment in the compression modulus, as compared to the neat foam.     

Influence of Monomer Structure,Initiation, and Porosity on Mechanical and Morphological Characteristics of Thiol-ene PolyHIPEs

Combining high internal phase emulsion templating with thiol-ene click chemistry produces porous polymers with high yields and degradable ester linkages. This study compares the influence of the monomer functionalities (tri versus tetra), internal phase volume, and initiation type (photo versus thermal) on the morphological and mechanical properties of poly(high internal phase emulsions) (polyHIPEs). For the synthesis of the polyHIPEs pentaerythritol tetrakis(3-mercaptopropionate) (PETMP, tetrafunctional), trimethylolpropane tris(3-mercaptopropionate) (TMPTMP, trifunctional), pentaerythritol tetraacrylate (PETA, tetrafunctional), and trimethylolpropane triacrylate (TMPTA, trifunctional) are used. The main factors influencing the properties of the polyHIPEs are the monomer structures and the internal phase volume, while the initiation type influences the morphology of the trifunctional system (pore size and morphology type) resulting in an interconnected cellular morphology in all cases except in the case of the photopolymerization of the emulsion with 85 vol% of the internal phase. The average pore diameter of the trifunctional system ranges from 8.0 to 27.8 µm, while for the tetrafunctional system it ranges from 8.1 to 12.3 µm. The compression moduli of the trifunctional system range from 0.093 to 0.240 MPa and for the tetrafunctional system they range from 1.906 to 7.670 MPa. The compression moduli decrease with increasing internal phase volume (porosity).     

Polyurethane/clay nanocomposites reinforced with carbon and glass fibres: study of mechanical and thermal properties,and the effect of electron beam irradiation

Polyurethane (PU) nanocomposites with 0, 1, 3, 5, and 7?wt-% nanoclay contents were prepared. X-ray diffraction patterns, transmission electron microscopy images, tensile test, and thermogravimetric analysis were utilised to reveal the morphological, mechanical, and thermal-resistant properties of the prepared nanocomposites. The exfoliated structure was obtained for nanoclay contents up to 3?wt-%. Incorporation of nanoclay to the PU matrix prompted the thermal stability of the polymer. A nanocomposite filled with 3?wt-% nanoclay showed the best tensile strength in the prepared nanocomposites. Subsequently, the nanocomposite with the 3?wt-% nanoclay was reinforced with carbon and glass fibres. Reinforcement of the PU/nanoclay matrix with carbon and glass fibres significantly ameliorated the tensile properties. Finally, the effects of the electron beam irradiation on the nanocomposites and fibre-reinforced composites were studied. Irradiation with the doses up to 500?kGy enhanced the mechanical and thermal properties. However, further irradiation deteriorated the mechanical and thermal-resistant properties.     

Impact of delignification on mechanical,morphological, and thermal properties of wood sawdust reinforced unsaturated polyester composites

Mechanical, morphological, and thermal properties of the raw and delignified wood sawdust (DWS) reinforced unsaturated polyester (UP) composites were evaluated. Composites were prepared using Resin Transfer molding technique by changing filler loading (5, 10, 15, and 20 wt%) for both raw and DWS reinforced UP. Mechanical (tensile and flexural), Fourier transform infrared spectroscopy (FTIR), morphological (scanning electron microscopy [SEM]) and thermal (thermogravimetric analysis [TGA]) properties were successively characterized. FTIR confirmed the removal of lignin from wood sawdust during the delignification process. The tensile strength, Young's modulus, and flexural strength values increased only up to 15% filler loading then decreased with increasing the filler. DWS reinforced composites had better mechanical properties compared to raw composites. SEM micrographs reveal that DWS reinforced composites have good compatibility with UP resin. According to TGA results, DWS reinforced composites showed enhanced thermal stability at the final decomposition stage above 400°C. J. VINYL ADDIT. TECHNOL., 24:185–191, 2018. © 2016 Society of Plastics Engineers     

Effect on modified nanoclay on dynamic mechanical and thermomechanical properties of natural fiber/polypropylene biocomposites

This study was conducted to investigate the effect of nanoclay addition on thermal and dynamic mechanical properties of polypropylene (PP) biocomposites reinforced with bleached red algae fiber (BRAF), kenaf fiber (KF), and cotton pulp fiber (CPF). The nano-biocomposites were fabricated with 40?wt.% loading of all natural fibers and addition of nanoclay at 5 or 10?wt.% loading by the melting compounding and compression molding techniques. The nanoclay effects on the thermal and dynamic mechanical properties of the biocomposites were analyzed as a function of properties of natural fibers such as chemical composition, fiber length, and surface morphology. Although the thermal decomposition temperature of nano-biocomposites decreased with the addition of nanoclay, the dimensional stability of biocomposites greatly improved with increasing nanoclay loading. Also, the dynamic mechanical properties of nano-biocomposites for the PP reinforced with BRAF, KF, and CPF were enhanced with the addition of 5?wt% nanoclay compared to those of biocomposites without nanoclay. The highest enhancement in dimensional stability was obtained for the nano-biocomposites reinforced with BRAF natural fiber. These increases can be attributed to a uniform distribution of nanoclay and to a good interfacial adhesion between the reinforcement and PP matrix. The well dispersed nanoclay particles can have good interactions with both natural fibers and polymer matrix, with the incorporation of the reinforcing natural fibers restricting the mobility of the polymer molecules resulting in the raised storage modulus values.     

Synthesis and characterization of porous polydimethylsiloxane structures with adjustable porosity and pore morphology using emulsion templating technique

Porous polydimethylsiloxane (PDMS) framework with adjustable pore structures has been fabricated by polymerization of the continuous phase in the emulsion templates. Different types of surfactants, including nonionic (Triton X-100), cationic (Benzalkonium chloride), anionic (sodium dodecyl sulfate), and silicone-based block copolymer were used to stabilize the water-in-oil emulsion system. Deionized water with a wide range of internal phases varying from 10% to 60% by weight was employed to make the low internal phase emulsion and medium internal phase emulsion. The effect of surfactant type, surfactant concentration, and the internal phase volume on the stability of the emulsion, pore morphology, and pore size distribution was explored. The stability of the emulsion was investigated by comparing the pore morphology of the cured sample at different set times, such as 0, 6, and 72 h. Scanning electron microscopy was employed for the characterization of the porous structures. The image analysis was conducted, and the pore size distribution, porosity, and open-cell ratio of each sample were calculated. Interconnected pores have been seen in the porous PDMS made from emulsions with an internal phase larger than 30%. The results demonstrated that the frequency of open-cell pores and the pore size is dependent on the surfactant types.     

Lignin‐polystyrene composite foams through high internal phase emulsion polymerization

The composites made‐up from renewable fillers and polymer matrix have drawn great attention due to the renewable nature, improved thermal and mechanical properties, environmental issues and most importantly to reduce dependency on fossil fuel resources. In this work, kraft lignin in its modified form (butylated lignin) was used to make composites with polystyrene successfully through bulk polymerization and high internal phase emulsion (HIPE) polymerization. The kraft lignin was first modified to butyrated lignin by esterification using 1‐Methylimidazole as a catalyst in order to increase the compatibility as fillers with both monomer and polymer, which was further studied and verified through Hansen solubility parameter model. The thermal, mechanical, and structural properties of the lignin/polymer composites were systematically investigated. The incorporation of lignin in the composites could increase the modulus significantly and almost double (1,391 MPa) at 15 wt% of lignin loading as compared with bare composites. Excellent porous structure and mechanical properties are maintained with the lignin content as high as 10 wt% of the total foam mass. POLYM. ENG. SCI., 59:964–972, 2019. © 2018 Society of Plastics Engineers     

Thermomechanical properties of alkali treated jute‐polyester/nanoclay biocomposites fabricated by VARTM process

A systematic study was carried out to investigate the effect of alkali treatment and nanoclay on thermomechanical properties of jute fabric reinforced polyester composites (JPC) fabricated by the vacuum‐assisted resin transfer molding (VARTM) process. Using mechanical mixing and sonication process, 1% and 2% by weight montmorillonite K10 nanoclay were dispersed into B‐440 premium polyester resin to fabricate jute fabric reinforced polyester nanocomposites. The average fiber volume was determined to be around 40% and void fraction was reduced due to the surface treatment as well as nanoclay infusion in these biocomposites. Dynamic mechanical analysis (DMA) revealed enhancement of dynamic elastic/plastic responses and glass transition temperature (T_g) in treated jute polyester composites (TJPC) and nanoclay infused TJPC compared with those of untreated jute polyester composites (UTJPC). Alkali treatment and nanoclay infusion also resulted in enhancement of mechanical properties of JPC. The maximum flexural, compression, and interlaminar shear strength (ILSS) properties were found in the 1 wt % nanoclay infused TJPC. Fourier transform‐infrared spectroscopy (FT‐IR) revealed strong interaction between the organoclay and polyester that resulted in enhanced thermomechanical properties in the composites. Lower water absorption was also observed due to surface treatment and nanoclay infusion in the TJPC. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Effect of organoclay loading level on mechanical properties,thermomechanical behavior,and heat build‐up of natural rubber/organoclay nanocomposites

Sodium‐montmorillonite nanoclay was modified with octadecylamine and compounded with natural rubber (NR) by dry mixing method. The effects of organoclay loading level on mechanical properties, thermal–mechanical behavior, and heat build‐up of NR/organoclay nanocomposites were investigated. Temperature scanning stress relaxation technique was used to characterize the thermal–mechanical behavior of the composites. The morphological properties were assessed by X‐ray diffraction and transmission electron microscopy. Loading levels of organoclay below 5 phr gave improved mechanical properties and heat build‐up, along with exfoliated clay structure in the nanocomposites. On the other hand, with loading levels above 7 phr the organoclay tended to agglomerate, and X‐ray diffraction revealed an intercalated structure. In these cases, the excess residual organoclay caused significantly increased stress relaxation and heat build‐up. Unmodified sodium‐montmorillonite as filler did not significantly affect the mechanical and heat build‐up properties of NR vulcanizates. POLYM. COMPOS., 37:1735–1743, 2016. © 2014 Society of Plastics Engineers     

Enhanced thermal stability and flame retarding properties of recycled polyethylene based wood composites via addition of polyethylene/nanoclay masterbatch

Abstract

Barrier and mechanical properties of wood powder composites based on recycled polyethylene (RPE) were modified using a commercial nanoclay masterbatch. X-ray diffraction, dynamic rheology and thermogravimetric analysis measurements showed that nanoclay from the selected masterbatch was well dispersed and formed a percolation network in both virgin and RPEs. The resulting nanocomposites promoted the thermal stability of matrix significantly. Modification efficiency of nanoclay, however, was evidently influenced by the type of matrix, where the strongest effect was achieved in a low viscosity virgin high density PE. The masterbatch was incorporated into an industrial formula designed extrusion quality RPE/wood flour composite. Processing procedures, mainly compounding cycles, and material composition, mainly clay content and type of coupling agent, were optimised. Two extrusion cycles led to higher uniformity of resulting composites than one cycle. Addition of a coupling agent, which has medium viscosity and plenty functional groups, led to enhanced tensile strength. The twice compounded composites were well stiffened and strengthened via combination of 6 wt-% clay and medium viscosity coupling agent. All composites without the addition of nanoclay burned faster after ignition and dripped much earlier and more compared to the composites containing nanoclay even with as small amount as 3 wt-% and being compounded once. The material with 6 wt-% clay showed the best sample integrity and burned slowest of all the tested composites. Furthermore, no dripping during combustion was seen for this material. This study shows that the incorporation of nanoclay using the selected masterbatch can effectively improve the flame retarding properties of RPE based wood composites.     

聚酯型阳离子水性聚氨酯乳液的合成研究

采用聚酯二醇(JW2503),甲苯二异氰酸酯(TDI),N-甲基二乙醇胺(MDEA)为基本原料,用丙酮法合成了聚酯型阳离子水性聚氨酯乳液。讨论了NCO／OH比值、MDEA的加入方式及其用量、反应温度等因素对乳液性能的影响。实验结果表明,当NCO／OH比值为2.7,MDEA的用量占树脂的6％-7％,且采用饥饿加料的方式滴加MDEA,初聚体合成温度为65℃,引入亲水扩链基团的扩链反应温度为40℃,中和度为90％-100％时合成的聚酯型阳离子水性聚氨酯乳液具有较好的贮存稳定性,且涂膜的耐水性和机械性能良好。     

Thermal,mechanical properties,and low‐temperature performance of fibrous nanoclay‐reinforced epoxy asphalt composites and their concretes

Epoxy asphalt (EA) concretes have been widely used in the pavement of orthotropic steel bridge decks. The objective of this study was to figure out the enhanced effects of natural fibrous attapulgite (ATT) as a reinforced nanofiller in ATT/EA nanocomposites through a comparison of the properties of the composites with a series of various nanoclay loadings. The rheological properties, glass transition, thermal stability, mechanical properties, and morphology of the ATT/EA composites were characterized. Furthermore, the low‐temperature flexibility of the ATT/EA concretes was investigated. The test results show that the addition of ATT had no significant effect on the rotational viscosity of EA in the initial stage of the curing reaction. In addition, the ATT/EA composites showed better performance than the neat one in thermal stability with a higher glass‐transformation temperature. The tensile strength and elongation at break of the ATT/EA composites at a loading of 0.5 wt % ATT were 21 and 22% higher than those of the neat EA. The addition of ATTs also enhanced the low‐temperature flexibility of the EA concretes. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41694.     

Water-containing resin based on unsaturated polyester

Unsaturated polyester resins containing water were prepared through two steps: formation of a stable W/O emulsion of polyester prepolymer and subsequent polymerization of the emulsion. In this paper, conditions for formation of the resins from the W/O type emulsion and the heat-protection properties of the resulting water-containing resins are reported. The stability of the emulsions was measured, and the results are discussed in relation to the gelation time, since the polymerization of the emulsions is required to proceed faster than their disintegration. It was found that with increasing viscosity of the emulsions their stability increases and the gelation time shortens. The above requirement is fulfilled at almost all regions of emulsifier concentration where stable W/O emulsions are formed. Water-containing unsaturated polyester resins exhibit a remarkable heat-protection effect at elevated temperatures (500 and 2500°C.) in comparison with polyester resins not containing water.     

Morphological,mechanical, tribological,and thermal expansion properties of organoclay reinforced polyethylene composites

The morphological, mechanical, thermal, and tribological properties of high‐density polyethylene (HDPE) composites reinforced with organo‐modified nanoclay (3 and 6 wt%) were studied. A commercial maleic anhydride‐based polymeric compatibilizer (PEgMA) was used to improve the adhesion between the polyethylene and clay. Transmission electron microscopy (TEM) characterization of composites revealed that nanoclay exists mainly in a multilayered structure in the HDPE matrix. Mechanical testing of composites showed that Young's modulus and tensile strength increased with nanoclay content. Coefficients of the linear thermal expansion (CLTE) of HDPE–PEgMA–clay composites were slightly lower in the flow direction than those of HDPE–PEgMA. The tribological properties were measured in dry conditions against a steel counterface. The friction coefficient of the matrix was decreased by the addition of clay. Electron microscopic results suggested that the wear mechanism for HDPE and HDPE composites was mainly adhesive. Clay agglomerates were observed on the worn surfaces of the composites, which may partly explain decreased friction. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers