Application of benzotriazole reactive UV absorbers to cellulose and determining sun protection of treated fabric spectrophotometrically

UV absorbers for treating cotton textiles with the aim of increased protection against harmful effects of UV component of solar radiation have been prepared by reactions of five different aminophenylsulfobenzotriazoles with the condensation product of 4‐aminophenyl‐sulfatoethylsulfone and cyanuric chloride. The UV absorbers with two different reactive groups (monochlorotriazine and aromatic vinylsulfone), capable of formation of covalent bonds with hydroxyl groups of cellulose, were applied to one cellophane foil and two cotton fabrics of different porosities. This treatment increased the ultraviolet protection factor from a value of UPF = 3 to UPF = 100 and above. For attaining a high UPF value, the cotton material should exhibit low porosity. The UV absorbers with 2‐hydroxyphenyl group are stable in light and do not fluoresce on the fabric on contrary to derivatives without 2‐hydroxyphenyl group or with 2‐methoxyphenyl group. The high photostability of absorbers is explained by the possibility to disperse the absorbed energy of UV radiation in the form of harmless energy such as IR radiation (heat) through the reversible hydrogen bond between phenolic hydroxyl group and triazine cycle. The UV filters block the effect of optical brightening agents on cotton by quenching the fluorescence. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Flame retardant finishing of the polyester/cotton blend fabric using a cross‐linkable hydroxy‐functional organophosphorus oligomer

Blend fabrics of cotton and polyester are widely used in apparel, but high flammability becomes a major obstacle for applications of those fabrics in fire protective clothing. The objective of this research was to investigate the flame retardant finishing of a 50/50 polyester/cotton blend fabric. It was discovered previously that N,N′‐dimethyloldihydroxyethyleneurea (DMDHEU) was able to bond a hydroxy‐functional organophosphorus oligomer (HFPO) onto 50/50 nylon/cotton blend fabrics. In this research, the HFPO/DMDHEU system was applied to a 50/50 polyester/cotton twill fabric. The polyester/cotton fabric treated with 36% HFPO and 10% DMDHEU achieved char length of 165 mm after 20 laundering cycles. The laundering durability of the treated fabric was attributed to the formation of polymeric cross‐linked networks. The HFPO/DMDHEU system significantly reduced peak heat release rate (PHRR) of cotton on the treated polyester/cotton blend fabric, but its effects on polyester were marginal. HFPO/DMDHEU reduced PHRR of both nylon and cotton on the treated nylon/cotton fabric. It was also discovered that the nitrogen of DMDHEU was synergistic to enhance the flame retardant performance of HFPO on the polyester/cotton fabric.     

Preparation and properties of bacterial cellulose/graphene oxide composite films using dyeing method

In this study, bacterial cellulose (BC) hydrogels were cultured from a kombucha SCOBY starter. The scanning electron microscopy (SEM) results indicated that the dried BC exhibited an interpenetrating fibrous mat. The BC films harvested for 5, 10, and 15 days were 15–19, 14.4–24, and 30–31 μm thick, respectively. Then, BC/graphene oxide (GO) composite films were prepared via the exhaust dyeing method. GO sheets penetrated the BC matrix, resulting in the formation of a BC/GO composite, as revealed by the SEM analysis results. The mechanical properties of the composite films were investigated. Compared with virgin BC, the tensile strength of the composite films was higher, while the %E at break was lower, resulting in a significant increase in the Young's modulus. The X-ray diffraction results indicated that an increase in the dyeing time (0.5–2 h) gradually induced cellulose crystalline conformation, which in turn affected the swelling ability, mechanical properties, and electrical properties of the BC/GO composite films. After the reduction of GO to reduced GO (rGO), flexible conductive BC/rGO films were obtained, as confirmed by their resistivity values. Thus, flexible conductive composite films with excellent mechanical properties were successfully fabricated.     

Impact of blend ratio on the properties of graphene oxide‐filled carboxylated acrylonitrile–butadiene rubber/styrene–butadiene rubber blends

Carboxylated acrylonitrile–butadiene rubber (XNBR) and styrene–butadiene rubber (SBR) composites with 3 phr (parts per hundred rubber) graphene oxide (GO) were prepared using a latex mixing method. Effects of XNBR/SBR blend ratios on the mechanical properties, thermal conductivity, solvent resistance and thermal stability of the XNBR/SBR/GO nanocomposites were studied. The tensile strength, tear strength, thermal conductivity and solvent resistance of the XNBR/SBR/GO (75/25/3) nanocomposite were significantly increased by 86, 96, 12 and 21%, respectively, compared to those of the XNBR/SBR (75/25) blend. The thermal stability of the nanocomposite was significantly enhanced; in other words, the temperature for 5% weight loss and the temperature of the maximal rate of degradation process were increased by 26.01 and 14.97 °C, respectively. Theoretical analysis and dynamic mechanical analysis showed that the GO tended to locate in the XNBR phase, which led to better properties of the XNBR/SBR/GO (75/25/3) nanocomposite. © 2017 Society of Chemical Industry     

石墨烯/棉织物制备及其电热性能研究

采用丝网印刷方式将氧化石墨烯浆料印制在棉织物表面,再经还原方法得到了电热性能优良的石墨烯棉织物。综合分析织物表面形貌、表面电阻及发热性能,探究了印制次数、还原浓度、还原时间及还原剂种类对石墨烯棉织物发热性能影响。结果表明,印制次数为10次,还原浓度为5 mg/mL,时间6 h,施加在两端电压为24 V时,织物的表面电阻为4.0 kΩ/cm,表面温度为46.8℃,电热性能达到最佳。     

Facile preparation of silver/reduced graphene oxide/chitosan colloid and application of the nanocomposite in antibacterial and catalytic activity

Reduced graphene oxide (RGO) decorated with silver nanoparticles (AgNPs) was synthesized by a facile solution‐based approach in chitosan (CS) solution. The morphology and elemental composition of as‐prepared Ag/RGO/CS colloid were characterized by SEM and energy dispersive X‐ray spectroscopy, respectively. TEM images show that most of the AgNPs are uniformly dispersed in the CS matrix while the other nanoparticles are decorated on the RGO nanosheets. XRD indicates that the interlayer distance of RGO is between 0.34 and 1.87 nm while the diameter of face‐centered cubic AgNPs is no more than 30 nm. Fourier transform infrared spectroscopy of the Ag/RGO/CS colloid confirms the formation of AgNPs and RGO. X‐ray photoelectron spectroscopy proves that both the Ag ? O bond and the C ? N bond exist in the nanocomposite. Antimicrobial assays were performed using the most common species of Gram bacteria. The inhibitory effect indicates that the incorporation of AgNPs and RGO significantly improves the antimicrobial activity of CS colloid. In addition, the nanocomposite colloid exhibits significant catalytic activity toward the reduction of 4‐nitrophenol by NaBH₄. © 2018 Society of Chemical Industry     

The effect of graphene oxide on UV curing kinetics and properties of SU8 nanocomposites

In the present study SU8 nanocomposites were prepared by incorporating graphene oxide (GO ), and its effect on the UV curing kinetics, morphology, electrical, hardness and thermal properties of the nanocomposites were investigated at different loading levels of GO (0.1 ? 3 wt%). Studying the reaction kinetics of the UV curing process by means of real‐time infrared spectroscopy showed that the polymerization rate and the final conversion of epoxy groups was related to the loading level of GO in the nanocomposites. An autocatalytic kinetics model of the curing reaction confirmed the effect of GO nanoparticles on the curing rate constant (k ), the order of the initiation reaction (m ) and the ultimate conversion of the UV ‐cured nanocomposites. Appropriate experimental observations indicated that dispersion of GO within the resin plays a critical role on the cure kinetics and final conversion. The results of the kinetics modeling and morphological observations showed that the curing rate constant of the nanocomposites is highly dependent on the GO content and its dispersion state, indicating that GO prevents epoxy resin crosslinking by photoinitator deactivation. Moreover, oxygen functionalities, such as hydroxyl and carboxyl groups, on the surface of GO facilitate interfacial interactions between epoxy groups from the matrix and GO . Electrical conductivity measurements demonstrated that the UV ‐induced photo‐cured GO filled resins are conductive SU8 nanocomposites. It was observed that the thermal stability of the nanocomposites is enhanced due to the dispersion of GO in the matrix. Moreover, the microhardness analysis showed that addition of GO to neat SU8 increases the mechanical hardness of the nanocomposite. © 2016 Society of Chemical Industry     

Effects of crosslinking agents on the physical properties of polyimide/amino‐functionalized graphene oxide hybrid films

The effects of crosslinking agents (crosslinkers) on polyimide (PI)/graphene oxide (GO) hybrid films were extensively investigated. The surface of GO was modified with amino groups using 4‐aminobenzylamine to improve compatibility with pyromellitic dianhydride/4,4′‐oxydianiline PI, and two kinds of crosslinkers were used: tris(4‐aminophenyl)amine and 1,3,5‐triazine‐2,4,6‐triamine (melamine). The mechanical, thermal and optical properties of the PI hybrid films were investigated. In particular, the transparency and physical properties of the PI hybrid films containing amino‐functionalized GO with homogeneous dispersion were improved. As the content of the crosslinker increased, a crosslinking network was formed between the PI chains, and the stiffness of the hybrid films was increased. The glass transition temperature, heat resistance and mechanical properties were also enhanced. The PI hybrids prepared with a rigid crosslinker exhibited higher optical transparency due to the reduction of the intermolecular charge transfer interactions with increasing interchain spacing between the PI chains. © 2018 Society of Chemical Industry     

Polyaniline nanorod adsorbed on reduced graphene oxide nanosheet for enhanced dielectric,viscoelastic and thermal properties of epoxy nanocomposites

In this work, polyaniline nanorod adsorbed on reduced graphene oxide (P@G) hybrid filler was prepared via in situ polymerization of aniline monomer in the presence of reduced graphene oxide as template. Fourier transform infrared, X-ray diffraction, field emission scanning electron microscopy, and high-resolution transmission electron microscopy images revealed the formation of P@G hybrid. The P@G hybrid was dispersed in dichlorobenzene and then introduced into epoxy resin at different loadings. The epoxy nanocomposites containing 9 wt% P@G hybrids (E/P@G9) exhibited a maximum DC conductivity of 1.34 × 10⁻⁵ S/cm that is eight orders higher compared to pure epoxy. At 10³ Hz, a dielectric constant (ε′) of 163 was attained for E/P@G9, nearly 34 times higher than pure epoxy. A percolation threshold of 4 vol% was observed for ε′. Dynamic mechanical studies showed that significant enhancement in storage modulus values were exhibited for 3 and 5 wt% of hybrids. The glass transition temperature showed a maximum shift of 10°C to higher temperatures at 3 wt% loading of P@G hybrids (E/P@G3). The tensile strength, Young's modulus, and impact strength of the E/P@G3 nanocomposites enhanced by 19.7, 72, and 12%, respectively. The thermal stability of the epoxy nanocomposites also enhanced with the addition of P@G hybrid.     

Influence of functionalized reduced graphene oxide and compatibilizer on mechanical,thermal and morphological properties of polypropylene/polybutene-1 (PP/PB-1) blends

Polypropylene/Polybutene-1 (PP/PB-1) blends and nanocomposites containing pristine partially reduced graphene oxide (rGO) and chemically functionalized rGO (FrGO) with silane, and silane grafted with 1,12-dodecanediamine and 1,12-dodecanediol were studied. The effects of the chemical treatments on structure and thermal stability of rGO were first thoroughly investigated. Attenuated total reflectance Fourier infrared (ATR-FTIR) spectroscopy analyses of FrGO evidenced the existence of functional groups on rGO after each chemical treatment, while X-ray diffraction (XRD) results confirmed the effectiveness of the interlayer grafting process through shifting of the basal spacings as witnessed by increased d₀₀₂ values. Furthermore, thermogravimetric analysis (TGA) revealed that the functionalization of rGO resulted in improved thermal stability of rGO demonstrated by its increased thermal degradation temperature. The PP/PB-1 blends and their rGO and FrGO based nanocomposites were prepared by melt blending masterbatch process in the presence of an acrylic acid modified polypropylene compatibilizer (PP-g-AA). Mechanical testing showed that Young’s modulus and tensile strength of the PP/PB-1 blends significantly improved after co-addition of FrGO and PP-g-AA to form the nanocomposites, but it also endowed a drastic decrease in their elongation at break and especially in their impact strength. XRD analyses attested the successful formation of intercalated nanocomposites, and scanning electron microscopy (SEM) examinations disclosed a two-phase morphology consisting of PB-1 dispersed droplets in the PP matrix. SEM also indicated that the incorporation of PP-g-AA into the blends and the nanocomposites contributed to enhanced adhesion and dispersion of PB-1 phase and FrGO nanoparticles within the polymer matrix.     

Simple route for the preparation of graphene/poly(styrene‐b‐butadiene‐b‐styrene) nanocomposite films with enhanced electrical conductivity and hydrophobicity

This paper reports a simple route for the preparation of graphene/poly(styrene‐b‐butadiene‐b‐styrene) (SBS) nanocomposite films employing a vacuum filtration method. Graphene is exfoliated well by an electrochemical procedure and homogeneously dispersed in the polymer matrix. The prepared nanocomposite films were characterized by XRD, Fourier transform IR (FTIR) spectroscopy, X‐ray photoelectron spectroscopy (XPS), Raman spectroscopy, AFM and SEM. Morphological studies showed that graphene formed a smooth coating over the surface of SBS. The increase in graphene concentration induces the wrinkling of graphene sheets at the composite surface which causes a further increase in surface roughness. The FTIR, Raman and XPS spectra of graphene/SBS nanocomposite films indicate the strong interactions between graphene and the polymer matrix. According to the XRD patterns, introducing SBS into graphene did not modify the graphene structure additionally, i.e. the crystal lattice parameters do not depend on SBS content in graphene/SBS nanocomposite films. The graphene/SBS nanocomposite films also exhibited better hydrophobicity due to the increased surface roughness and lower sheet resistivity (reduced 10 times) compared to exfoliated graphene. © 2018 Society of Chemical Industry     

Conductive poly(vinylidene fluoride)/polyethylene/graphene blend‐nanocomposites: Relationship between rheology,morphology, and electrical conductivity

Relationship between rheology, morphology, and electrical conductivity of the poly(vinylidene fluoride)/polyethylene/graphene nano‐platelets ternary system (PVDF/PE/GnP) were investigated. All the blend nanocomposites were prepared via a two‐step melt mixing method. GnP (0.75 and 1.5 wt %) was first compounded with PVDF and then the resulted premixtuers were melt mixed with PE to achieve the desired compositions. The corresponding reference nanocomposites and filler‐less blends were also prepared. Effect of an interfacial agent (PEMA; maleic anhydride grafted polyethylene) was also studied in this work. The results of rheological analysis in conjunction with the Raman spectroscopy experiments revealed that GnP had higher affinity to PVDF than PE, which in turn led to creation of conductive networks of GnP (1.5 wt %) in PVDF matrix exhibiting the electrical conductivity of about 10^?2 (S/cm). Double percolated micro‐structure was predicted for the PE/PVDF 40/60 (wt/wt) blend containing low GnP content (0.9 wt %) and confirmed via direct electron microscopy and conductivity analysis. Using 5 wt % of the PEMA reduced the conductivity to 10^?5 (S/cm) and further increase in PEMA content to 10 wt % led to non‐conductive characteristics. The latter was attributed to the migration of GnP from the PVDF phase to PE/PEMA phase and hence disturbance of double percolated micro‐structure. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46333.     

Preparation of polyimide/siloxane‐functionalized graphene oxide composite films with high mechanical properties and thermal stability via in situ polymerization

An effective approach to prepare polyimide/siloxane‐functionalized graphene oxide composite films is reported. The siloxane‐functionalized graphene oxide was obtained by treating graphene oxide (GO) with 1,3‐bis(3‐aminopropyl)‐1,1,3,3‐tetra‐methyldisiloxane (DSX) to obtain DSX‐GO nanosheets, which provided a starting platform for in situ fabrication of the composites by grafting polyimide (PI) chains at the reactive sites of functional DSX‐GO nanosheets. DSX‐GO bonded with the PI matrix through amide linkage to form PI‐DSX‐GO films, in which DSX‐GO exhibited excellent dispersibility and compatibility. It is demonstrated that the obvious reinforcing effect of GO to PI in mechanical properties and thermal stability for PI‐DSX‐GO is obtained. The tensile strength of a composite film containing 1.0 wt% DSX‐GO was 2.8 times greater than that of neat PI films, and Young's modulus was 6.3 times than that of neat PI films. Furthermore, the decomposition temperature of the composite for 5% weight loss was approximately 30 °C higher than that of neat PI films. © 2015 Society of Chemical Industry     

Latex co‐coagulation approach to fabrication of polyurethane/graphene nanocomposites with improved electrical conductivity,thermal conductivity,and barrier property

This study describes a simple and effective method of synthesis of a polyurethane/graphene nanocomposite. Cationic waterborne polyurethane (CWPU) was used as the polymer matrix, and graphene oxide (GO) as a starting nanofiller. The CWPU/GO nanocomposite was prepared by first mixing a CWPU emulsion with a GO colloidal dispersion. The positively charged CWPU latex particles were assembled on the surfaces of the negatively charged GO nanoplatelets through electrostatic interactions. Then, the CWPU/chemically reduced GO (RGO) was obtained by treating the CWPU/GO with hydrazine hydrate in DMF. The results of X‐ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and Raman analysis showed that the RGO nanoplatelets were well dispersed and exfoliated in the CWPU matrix. The electrical conductivity of the CWPU/RGO nanocomposite could reach 0.28 S m^?1, and the thermal conductivity was as high as 1.71 W m^?1 K^?1. The oxygen transmission rate (OTR) of the CWPU/RGO‐coated PET film was significantly decreased to 0.6 cm³ m^?2 day^?1, indicating a high oxygen barrier property. This remarkable improvement in the electrical and thermal conductivity and barrier property of the CWPU/RGO nanocomposite is attributed to the electrostatic interactions and the molecular‐level dispersion of RGO nanoplatelets in the CWPU matrix. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43117.     

Effect of bio‐oil and epoxidized linseed oil on physical,mechanical, and biological properties of treated wood

In this article, the effects of bio‐oil and epoxidized linseed oil (ELO) on water absorption, tangential swelling, decay and insect resistance, thermo‐gravimetric analysis, and mechanical properties of treated wood samples were studied. The bio‐oil used in this article was by‐product of ThermoWood thermal modification process. Linseed oil and hydrogen peroxide were used to prepare ELO. The results indicated that the samples treated with bio‐oil had lower water absorption than that of the control group. The second treatment with ELO significantly reduced further the water absorption. The decay resistance of treated wood samples with 20% of bio‐oil against brown (Coniophora puteana) and white rot (Trametes versicolor) fungi was very high. According to the insect test results, increasing bio‐oil concentration from 10% to 20% significantly decreased surviving rate of Hylotrupes bajulus. Thermo‐gravimetric analysis showed that all treated samples had higher initial deterioration temperature than that of the control group. Regarding the wood strength, the impregnated bio‐oil generally reduced the mechanical properties of wood except modulus of elasticity (MOE). © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1562–1569, 2013     

Effects of compaction and UV exposure on performance of acrylate/glass‐fiber composites cured layer by layer

With an aim to reducing manufacturing costs, in general and specifically to provide a solution to the thick laminate curing depth issue for composite materials, UV curing technology was combined with a fiber placement process to fabricate acrylate/glass‐fiber composites. A novel layer‐by‐layer UV in situ curing method was employed in this article and interlaminar shear strength (ILSS) tests and SEM were used to evaluate the effect of processing parameters, including compaction force and UV exposure dose, on ILSS. The SEM images from short‐beam strength test samples and the results of ILSS showed that the fibers' distribution was uniform in the cured matrix resin resulting from the compaction forces and that beneficially influenced the ILSS of the composite greatly. However, the matrix resin produced large shrinkage stresses when it reached a high degree of conversion (DC) in one‐step, which resulted in poor interlaminar adhesion. In addition, the fast curing speed of UV on the composite resulted in poor wetting between fiber and resin, and accordingly resulted in lower ILSS. To overcome these problems and obtain high ILSS value composites, an optimized compaction force and UV exposure dose were determined experimentally. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Preparation and UV/Vis Spectroscopic Characterization of N,N‐Disubstituted 2‐Amino‐5‐arylazoselenazoles and Some of Their Carbocyclic and Heterocyclic Analogues

By coupling of aryldiazonium salts 5 with N,N‐disubstituted 2‐amino‐5H‐selenazoles 4 deeply coloured 5‐arylazo‐substituted 2‐amino‐selenazoles 6a—6l have been prepared and their solvatochromic properties determined by means of UV/Vis spectroscopy, and compared with the ones of several other arylazosubstituted N,N‐dialkylanilines 7a—7d , 2‐(N,N‐dialkylamino)‐thiophenes 8a—8e , and 2‐(N,N‐dialkylamino)‐thiazoles 9a—9c .