Morphology control of poly(lactic) acid/polypropylene blend composite by using silanized cellulose fibers extracted from coir fibers

The objective of this work is the use of cellulose fibers extracted from coir fibers as Janus nanocylinders to suppress the phase retraction and coalescence in poly(lactic) acid/polypropylene bio-blend polymers via prompting the selective localization of cellulose fibers at the interface using chemical modification. The untreated and modified cellulose fibers extracted from coir fibers using a silane molecule (tetraethoxysilane) were used as reinforcement and as Janus nanocylinder at two weight contents (2.5 wt% and 5 wt%) to manipulate the morphology of the bio-blends. Their bio-composites with PLA-PP matrix were prepared via melt compounding (at PLA/PP: 50/50). The treatment effect on component interaction and the bio-composites properties have been studied via Scanning electron microscopy, infrared spectroscopy, and differential calorimetry analysis. The mechanical and rheological properties of nanocomposites were similarly assessed. Young's modulus and tensile strength of PLA-PP nanocomposites reinforced by silanized cellulose fibers show a great enhancement as compared to a neat matrix. In particular, there was a gain of 18.5% in Young's modulus and 11.21% in tensile strength for silanized cellulose fiber-based bio-blend composites at 5 wt%. From the rheological point of view, it was found that the silanized cellulose fibers in PLA-PP at both fibers loading enhances the adhesion between both polymers leading to tuning their morphology from sea-island to the continuous structures with the appearance of PLA microfibrillar inside of bio-composites. This change was reflected in the relaxation of the chain mobility of the bio-blend composites.

     

Development and characterization of fully bio‐based polybenzoxazine‐silica hybrid composites for low‐k and flame‐retardant applications

In the present work, new classes of bio‐based polybenzoxazines were synthesized using eugenol as phenol source and furfurylamine and stearylamine as amine sources separately through solventless green synthetic process routes and were further reinforced with varying percentages (1, 3, 5, and 10 wt%) of silica (from rice husk) to attain hybrid composites. The molecular structure, cure behaviour, thermal stability, dielectric properties, and flame‐retardant behaviour of both benzoxazine monomers and benzoxazine composites were characterized using appropriate modern analytical techniques. The eugenol‐based benzoxazines synthesized using furfurylamine (FBz) and stearylamine (SBz) were cured at 223°C and 233°C, respectively. The differential scanning calorimetry (DSC) data reveal the glass transition temperatures (T_g) of FBz and SBz were 157°C and 132°C, respectively, and the maximum decomposition temperature (T_max) as obtained from thermogravimetric analysis (TGA), were found to be 464°C and 398°C for FBz and SBz, respectively. The dielectric constants for FBz and SBz obtained at 1 MHz were 3.28 and 3.62, respectively. Furthermore, varying weight percentages (1, 3, 5, and 10 wt%) of 3‐mercaptopropyltrimethoxysilane (3‐MPTMS) functionalized bio‐silica reinforced the composite materials as evidenced by their improved thermal stability and lower dielectric constant. Data obtained from thermal and dielectric studies suggested that these polybenzoxazines could be used in the form of adhesives, sealants, and composites for high performance inter‐layer low‐k dielectric applications in microelectronics.     

Mechanical property evaluation of glass–jute fiber reinforced polymer composites

The natural fibers such as jute, coir, hemp, sisal etc. are randomly used as reinforcements for composite materials because of its various advantages such as low cost, low densities, low energy consumption over conventional fibers. In addition, they are renewable as well as biodegradable, and indeed wide varieties of fibers are locally available. In this study, glass–jute fiber reinforced polymer composite is fabricated, and the mechanical properties such as tensile, flexural and impact behavior are investigated. The materials selected for the studies were jute fiber and glass fiber as the reinforcement and epoxy resin as the matrix. The hand lay‐out technique was used to fabricate these composites. Fractured surface were comprehensively examined in scanning electron microscope (SEM) to determine the microscopic fracture mode. A numerical procedure based on the finite element method was then applied to evaluate the overall behavior of this composite using the experimentally applied load. Results showed that by incorporating the optimum amount of jute fibers, the overall strength of glass fiber reinforced composite can be increased and cost saving of more than 30% can be achieved. It can thus be inferred that jute fiber can be a very potential candidate in making of composites, especially for partial replacement of high‐cost glass fibers for low load bearing applications. Copyright © 2016 John Wiley & Sons, Ltd.     

Comparison of copolymer emulsions of fluorine and siloxane‐containing acrylates with core–shell structure for water‐repellent cotton fabrics coatings

This paper described the synthesis of copolymer emulsions of fluorine and siloxane‐containing acrylates for water‐repellent cotton fabrics coatings. Chemical composition, morphology structure, and properties of the latex copolymers were investigated by Fourier transform infrared (FTIR), dynamic light scattering (DLS), gel permeation chromatography (GPC), and transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). Effects of water‐repellent functional monomers (R_f) on surface morphology, water contact angle, and water‐repellent properties of the coated fabric surface were also studied. The results indicated that R_f greatly influenced molecular mass distribution of the latex copolymers, the molecular aggregation states and orientation of R_f on the coated fabric surface, and water‐repellency of coated cotton fabrics. Copyright © 2014 John Wiley & Sons, Ltd.     

Biodegradability of poly(butylene succinate) (PBS) composite reinforced with jute fibre

Poly(butylene succinate) (PBS)/jute composites were prepared, and the effects of fibre content, diameter, surface modification and arrangement forms on the biodegradability were evaluated by compost-soil burial test. The weight losses of PBS/jute composites are higher than that of pure PBS film and bulk jute fibre, and decreased with increasing fibre content. The weight loss of PBS/10% jute composite after 180 days is 62.5%. In the case of the effect of fibre diameter, the weight loss is found to decrease with decreasing fibre diameter. For the effect of fibre surface modification, the order of higher weight loss is PBS/untreated jute > PBS/alkali treated jute > PBS/coupling agent treated jute. Furthermore, the composite of PBS/woven fabric has the highest weigh loss, followed by that of PBS/nonwoven fabric and PBS/bulk jute fibre, respectively.     

Superhydrophobic and superoleophilic polyethylene aerogel coated natural rubber latex foam for oil-water separation application

The oil-water separation has made an attention due to over-increased production of oily water from the industrial process and everyday routine of humans. The current work reports on preparation and characterization of High-Density Polyethylene (HDPE) aerogel coated Natural Rubber Latex foam (NRLF) with superhydrophobic and superoleophilic character, good sorption capacity for oil-water separation application and were investigated. The HDPE aerogel and the coated NRLF material was prepared by a cooling process from a solution of HDPE in xylene solvent (HDPE sole, which resulted into thermally induced phase separation of the Polyethylene molecular network). The HDPE aerogel coated NRLF displayed a porous surface morphology with particle-like structural features. The HDPE aerogel coated NRLF showed superhydrophobicity with static water contact angle >150°. The effect and recyclability of the HDPE aerogel coated NRLF for oil-water separation was investigated using different model oil solvents to explore their repeatable application in oil spill clean-up process. Modified NRLF shows an excellent mechanical property (compressibility). The average modulus and average stiffness of the modified NRLF increased with the increase of the concentration of HDPE sol. The modified superhydrophobic sponge has good durability under acid and base conditions.     

Effect of gamma radiation on the performance of jute fabrics-reinforced polypropylene composites

Jute fabrics-reinforced polypropylene (PP) composites (50% fiber) were prepared by compression molding. Composites were fabricated with non-irradiated jute fabrics/non-irradiated PP (C-0), non-irradiated jute fabrics/irradiated PP (C-1), irradiated jute fabrics/non-irradiated PP (C-2) and irradiated jute fabrics/irradiated PP (C-3). It was found that C-3 composite performed the best mechanical properties over other composites. Total radiation dose varied from 250–1000 krad and composites made of using 500 krad showed the best results. The optimized values (C-3 composites) for tensile strength (TS), bending strength (BS) and impact strength (IS) were found to be 63 MPa, 73 MPa and 2.93 kJ/m², respectively.     

Cardanol-based bisbenzoxazines

A new class of thermoset polymers was synthesized based on agrochemical renewable cardanol—a by-product of cashew nut industry. A solventless synthesis of bisbenzoxazine monomers based on bisphenol-A (b) and aniline (abbreviated as Bzb-A) and cardanol (c) with diamines namely bis-(4-(4-aminophenoxy)phenyl)ether (HP), bis-(3-(4-aminophenoxy)phenyl)ether (HM), 4,4′-diaminodiphenylsulphone (DDS) and 2,2-bis(4-(4-aminophenoxy)phenyl)propane (BA) was carried out. The benzoxazine monomers (Bzc-HP, Bzc-HM, Bzc-DDS and Bzc-BA) were characterized by ¹H-NMR and FTIR spectroscopy. The curing exotherm depended on the structure of the monomers. The onset curing temperature (T _o) was lowest for Bzb-A (460 K) and highest in Bzc-HM (518 K). The decomposition temperature for 5% mass loss (T _5%) of resins followed the order PBzb-A < PBzc-DDS < PBzc-BA < PBzc-HM ≈ PBzc-HP. The materials showed their potential as adhesives. Lap shear strength on steel plates followed the trend PBzc-DDS < PBzc-HM < PBzc-BA < PBzc-HP.     

Mechanical,low-velocity impact,and hydrothermal aging properties of flax/carbon hybrid composite plates

A hybrid of flax and carbon fibers was considered as an effective way to enhance the mechanical and hydrothermal resistance of flax-reinforced polymer composites. In this study, hybrid composites based on three layers of cross-ply flax fabrics, two layers of unidirectional carbon fabrics, and an epoxy resin were investigated in terms of the tensile, three-point bending, impact, and water absorption properties. The flax fabric reinforcement of the hybrid composites contributed to an improvement in the toughness, whereas the carbon fabric contributed to an improvement in their hydrothermal resistance and overall strength and stiffness. The hybrid composites with carbon fibers on the surface (CFFFC) exhibited brittle failure in the tensile test, whereas those with alternating layers (FCFCF) exhibited greater plastic deformation. In addition, the failure strain of the CFFFC samples showed a negative hybrid effect, whereas that of the FCFCF samples improved 63.5% compared with that of carbon-fiber-reinforced polymer composites. A positive hybrid effect on the impact performance of hybrid reinforced epoxy composites containing the unidirectional carbon fabric and cross-ply flax fabric was observed. At 40 °C and 80% relative humidity, the diffusion rate of water molecules in the FCFCF samples was 16 times that in the CFFFC samples.     

Wear behavior of wood–plastic composites in alternate simulated sea water and acid rain corrosion conditions

To investigate the effect of alternate simulated sea water and acid rain corrosion on the wear resistance properties of wood–plastic composites, sorghum straw fiber-reinforced polyvinyl chloride (SPVC) composites prepared through extrusion molding were studied. The most detrimental alternating corrosion parameters were evaluated with the orthogonal design method, and the samples were then processed considering superimposed corrosion with the worst parameters. The results show that the worst alternating corrosion parameters were: sea water salinity 3.5% × sea water temperature 55 °C + acid rain pH 2.5 × acid rain temperature 55 °C. Longer alternating corrosion periods resulted in worse physical, mechanical, and thermal properties of the SPVC composites, a PVC matrix that was more easily softened in the frictional environment, and fibers more easily pulled-out to form abrasive particles. Debris of broken or pulled-out fibers moving with high-speed in a high-temperature and high-load frictional contact environment can cause severe abrasive wear.     

Hierarchical structure microspheres of PCL block copolymers via electrospraying as coatings for fabric with mechanical durability and self‐cleaning ability

The various morphology and structure microspheres were fabricated via one‐step single‐solvent electrospraying of hydrophilic and hydrophobic block modified copolymer of polycaprolactone (PCL). A honeycomb‐like hierarchical structure microspheres of PCL‐b‐PTFOA(4h) and abundant nanometer pores of PCL‐b‐PEG400 microspheres were obtained due to the solvent evaporation, thermally and polymer diffusion‐induced phase separation effect. Furthermore, a superhydrophobic coatings and robust superhydrophobic‐coated cotton woven fabric surfaces were prepared by using PCL‐b‐PTFOA(4h) microspheres with hierarchical structure and low surface energy. The contact angle (CA) and sliding angle (SA) of PCL‐b‐PTFOA(4h) microspheres‐coated cotton woven fabric surfaces reached 164.4 ± 5.5° and 6.8 ± 0.5°, respectively, which allows for self‐cleaning. The self‐cleaning test demonstrated that the coated superhydrophobic surface could shed aqueous dyes and dust without any trace. The superhydrophobic‐coated fabric shows good soaping fastness against mechanical abrasion without significant reduction of CA. This electrospraying coating of block copolymers can provide a simple, facile, and promising technique for producing multifunctional textiles.     

A rapid and simple ultra high performance liquid chromatography method for the simultaneous determination of methoxyphenol derivatives involved in the eugenol catabolic pathway

An efficient ultra high performance liquid chromatography method of separation was developed for the analysis of six important methoxyphenol derivatives involved in the eugenol catabolic pathway. In the present study, an Acquity UPLC BEH C₁₈ column was used for the chromatographic separation of the industrially important phenolic compounds such as vanillin, vanillic acid, ferulic acid, coniferyl alcohol, and coniferyl aldehyde obtained during microbial transformation of eugenol. Eluted components were identified using the dual wavelength (254 and 310 nm) UV detector. A gradient method of elution using mobile phase of aqueous 1 mM trifluoroacetic acid (Solvent A) and methanol (Solvent B) at a flow rate of 0.3 mL/min separated all the five intermediate methoxyphenol derivatives along with their precursor eugenol within 15 min with stable baseline resolution. Method validation was performed for the accurate quantification of vanillin, coniferyl aldehyde, and eugenol using the parameters of linearity, specificity, precision, limit of detection, limit of quantification, and robustness. The developed method would be helpful for clear separation and identification of the five most important intermediate metabolites of the eugenol catabolism pathway.     

Trace determination of parabens in cosmetics and personal care products using fabric‐phase sorptive extraction and high‐performance liquid chromatography with UV detection

A simple, fast, and sensitive analytical protocol using fabric‐phase sorptive extraction followed by high performance liquid chromatography with ultraviolet detection has been developed and validated for the extraction of five parabens including methylparaben, ethylparaben, propylparaben, butylparaben, and benzylparaben. In the present work, sol‐gel polyethylene glycol coated fabric‐phase sorptive extraction membrane is used for the preconcentration of parabens (polar) from complex matrices. The use of fabric‐phase sorptive extraction membrane provides a high surface area which offers high sorbent loading, shortened equilibrium time, and overall decrease in the sample preparation time. Various factors affecting the performance of fabric‐phase sorptive extraction, including extraction time, eluting solvent, elution time, and pH of the sample matrix, were optimized. Separation was performed using a mobile phase consisting of water:acetonitrile (63:37; v/v) at an isocratic elution mode at a flow rate of 0.9 mL/min with wavelength at 254 nm. The calibration curves of the target analytes were prepared with good correlation coefficient values (r² > 0.9955). The limit of detection values range from 0.252 to 0.580 ng/mL. Finally, the method was successfully applied to various cosmetics and personal care product samples such as rose water, deodorant, hair serum, and cream with extraction recoveries ranged between 88 and 122% with relative standard deviation <5%.     

Industrial cutting waste granite dust reinforced cardanol benzoxazine/epoxy resin hybrid composites for high-voltage electrical insulation applications

An attempt has been made to develop hybrid composites from benzoxazine monomer (C-ddm) hybridized with DGEBA epoxy resin (EP) and reinforced with varying weight percentages (20 wt%, 40 wt%, 60 wt%, 80 wt% and 100 wt%) of glycidoxypropyltrimethoxy- silane (GPTMS) functionalized granite dust (GD) obtained from industrial granite cutting and polishing process in order to utilize them for electrical insulation applications. The thermal stability of granite dust reinforced poly(EP-co-C-ddm) composites was studied by TGA analysis. Among the composites samples studied, 100 wt% GD reinforced poly(EP-co-C-ddm) composites possess better thermal stability than that of other neat matrices and composites. Among the composites prepared using varying weight percentages of functionalized GD reinforcement, it was observed that 80 wt% GD reinforced poly(EP-co-C-ddm) composites possesses better hydrophobic character than that of other neat matrices and composites. The value of LOI calculated for neat matrix (poly[EP-co-C-ddm]) and 20 wt%, 40 wt%, 60 wt%, 80 wt% and 100 wt% GD reinforced composites was found to be 22, 28, 34, 40, 43 and 45 respectively. The 80 wt% GD reinforced poly(EP-co-C-ddm) composites possess the higher values of tensile strength and flexural strength of 47 MPa and 140 MPa, respectively than those of their samples. The values of electrical surface resistivity and electrical volume resistivity of all the neat matrices and GD reinforced polybenzoxazine composites were found to be in the order of 10¹² and 10¹³ respectively. The values of dielectric strength obtained from break down voltage (BDV) for neat matrix [poly(EP-co-C-ddm)] and 20 wt%, 40 wt%, 60 wt%, 80 wt% and 100 wt% of GD reinforced poly(EP-co-C-ddm) composites are 15.0, 15.5, 16.5, 17.0, 17.0 and 17.0 kV/mm, respectively. Data obtained from thermal stability, hydrophobic behavior and dielectric studies it was inferred that the hybrid polymer composites developed in the present work can be conveniently used in the form insulators, sealants, adhesives and matrices where application demands at high-performance industrial and engineering applications.     

Radar transparent glass fabric reinforced polyetherimide/Cloisite 30B nanocomposites

High performance radar transparent materials (RTMs) are important materials for the fabrication of radomes, nosecones, etc. of high velocity aerospace vehicles. RTMs with good mechanical performance and temperature capability are required for such applications. Toward this, fabric reinforced nano‐reinforced matrix composites (FRNCs), using reinforcing E‐glass fabric in Cloisite 30B reinforced polyetherimide (PEI) nanocomposite matrix (GNRPEI), was prepared. The properties of GNRPEI were evaluated and compared with E‐glass fabric reinforced PEI composites (GRPEI) with special reference to their radar transparent character for aerospace applications. Tensile and flexural properties along with interlaminar shear strength of GRPEI were observed to be lower than those of GNRPEI. Thermal behavior of both the composites was similar in differential scanning calorimetry and thermal gravimetric analysis. But, in dynamic mechanical analysis, an increase in storage modulus and decrease in loss tangent were observed in GNRPEI compared to GRPEI. The values of dielectric constant and loss tangent of GNRPEI were lesser than those of GRPEI, but no significant difference was observed in the values of transmission and reflection losses for both the composites at 8–12 GHz frequency. FRNCs, based on organoclay reinforced PEI matrix, hold good promise as high performance RTMs. Copyright © 2010 John Wiley & Sons, Ltd.     

Variation of mechanical and thermal properties of the thermoplastics reinforced with natural fibers by electron beam processing

With restrictions for environmental protection being strengthened, the thermoplastics reinforced with natural fibers (NFs) such as jute, kenaf, flax, etc., appeared as an automobile interior material instead of the chemical plastics. Regardless of many advantages, one shortcoming is the deformation after being formed in high temperature of about 200 °C, caused by the poor adhesion between the natural fibers and thermoplastics. Also, the energy saving in connection with car air-conditioning becomes very important. In this study, the thermal conductivity, tensile strength, and deformation of several kinds of thermoplastic composites composing of 50% polypropylene (PP) and 50% natural fiber irradiated by the electron beam (energy: 0.5 MeV, dose: 0–20 kGy) were measured. The length and thickness of PP and NF are 80±10 mm and 40–120 μm, respectively. The results show that the thermal conductivity and the tensile strength changed and became minimum when the dose of electron beam is 10 kGy, and the deformation after the thermal cycle were reduced by the electron beam.     

Layer-by-layer assembly of silica-based flame retardant thin film on PET fabric

A novel method to improve flame retardant properties of textile fabric using multilayered thin films was evaluated. In this work, PET fabrics were coated with silica nanoparticles using layer-by-layer assembly. Five bilayers of positively and negatively charged colloidal silica (<10 nm average thickness) increased time to ignition and decreased heat release rate peak of PET fabric by 45% and 20%, respectively. In vertical burn test, this same nanocoating dramatically reduced burn time and eliminated melt dripping. This study demonstrates the ability to impart flame retardant behavior using a water-based, environmentally-friendly protective coating.     

具有水下超疏油性能的MXene高效油水分离膜

基于二维材料MXene(Ti₃C₂T_x)的化学组成和纳米片状结构, 在不锈钢网上制备了具有MXene微纳结构表面的新型亲水和水下超疏油分离膜. 对于不同类型的油-水混合物, 该膜材料可实现重力驱动的高效油水分离, 收集的水中残油量小于4 mg/L, 具有高分离效率(>99.99%), 水通量高达57.52 L·m^-2·s^-1. 此外, 经高温处理和多种有机溶剂浸泡后MXene膜仍具有高效的油水分离性能, 并表现出优异的稳定性和循环性.     

Bio-based benzoxazine from renewable L-tyrosine: Synthesis,polymerization, and properties

Developing thermosets derived from renewable sources is of great importance. In this work, a fully bio-based benzoxazine monomer, 3,6-bis((3-(furan-2-ylmethyl)-3,4-dihydro-2H-benzo[e][1,3]oxazin-6-yl)methyl)piperazine-2,5-dione (TCDPF), is conveniently synthesized from L-tyrosine cyclic dipeptide (TCDP), furfurylamine and paraformaldehyde. The chemical structure of TCDPF is confirmed by nuclear magnetic resonance spectroscopy and Fourier transform infrared spectroscopy (FT-IR) techniques. The curing behavior of TCDPF is investigated by differential scanning calorimetry and in situ FT-IR techniques. After temperature-programmed curing, the thermomechanical property and thermal stability of the resulting TCDPF polymer (PTCDPF) are evaluated by dynamic mechanical analysis and thermogravimetric analysis techniques, respectively. It is found that PTCDPF have excellent comprehensive performance such as high glass transition temperature (T_g = 322 °C), high thermal degradation temperature (T_5% = 342 °C, T_10% = 395 °C in N₂ atmosphere), and high char yield (CY = 51.3% at 800 °C in N₂ atmosphere). The results demonstrate that L-tyrosine is a promising bio-based raw material for preparing high performance polybenzoxazines.     

Design and fabrication of thin polymer coating on cotton fabric surface to impart hydrophobicity: An admicellar polymerization approach

The fluorinated poly(trifluoroethylmethacrylate) thin polymers were successfully prepared through free radical initiating admicellar polymerization approach using fluorosurfactant and 2,2,2-trifluoroethylmethacrylate (TFEM, monomer) system, which was initiated with potassium persulfate (KPS) initiator. The structure of the resultant polymer and morphology of the modified cotton fabric surfaces were confirmed by SEM and EDX analysis. The surface wettability of the modified cotton fabric was characterized by a water drop stay time and contact angle (CA) measurement. The coated cotton fabric exhibited excellent hydrophobicity with a water contact angle of 137.79°.