Showing papers in "Journal of Applied Polymer Science in 2014"
TL;DR: A review of the traditional viscous fluids used in conventional hydraulic fracturing operations as well as the new family of fluids being developed for both traditional and unconventional reservoirs can be found in this paper.
Abstract: Hydraulic fracturing has been used by the oil and gas industry as a way to boost hydrocarbon production since 1947. Recent advances in fracturing technologies, such as multistage fracturing in horizontal wells, are responsible for the latest hydrocarbon produc- tion boom in the US. Linear or crosslinked guars are the most commonly used fluids in traditional fracturing operations. The main functions of these fluids are to open/propagate the fractures and transport proppants into the fractures. Proppants are usually applied to form a thin layer between fracture faces to prop the fractures open at the end of the fracturing process. Chemical breakers are used to break the polymers at the end of the fracturing process so as to provide highly conductive fractures. Concerns over fracture conduc- tivity damage by viscous fluids in ultra-tight formations found in unconventional reservoirs prompted the industry to develop an alter- native fracturing fluid called "slickwater". It consists mainly of water with a very low concentration of linear polymer. The low concentration polymer serves primarily to reduce the friction loss along the flow lines. Proppant-carrying capability of this type of fluids is still a subject of debate among industry experts. Constraints on local water availability and the potential for damage to formations have led the industry to develop other types of fracturing fluids such as viscoelastic surfactants and energized fluids. This article reviews both the traditional viscous fluids used in conventional hydraulic fracturing operations as well as the new family of fluids being devel- oped for both traditional and unconventional reservoirs. V C 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131 ,4 0735.
532 citations
TL;DR: In this paper, a macroscopic compression test utilizing a simple custom-built instrument was employed to measure polydimethylsilox-ane (PDMS) elastic modulus.
Abstract: A macroscopic compression test utilizing a simple custom-built instrument was employed to measure polydimethylsilox- ane (PDMS) elastic modulus. PDMS samples with varying crosslinking density were prepared with the elastomer base to the curing agent ratio ranging from 5 : 1 to 33 : 1. The PDMS network elastic modulus varied linearly with the amount of crosslinker, ranging from 0.57 MPa to 3.7 MPa for the samples tested. PDMS elastic modulus in MPa can be expressed as 20 MPa/PDMS base to curing agent ratio. This article describes a simple method for measuring elastic properties of soft polymeric materials. V C 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41050.
391 citations
TL;DR: A review of the state-of-the-art research on the use of graphene, GO, and rGO for barrier applications, including few-layered graphene or its derivatives in coated polymeric films and polymer nanocomposites consisting of chemically exfoliated GO and reduced graphene oxide (rGO) nanosheets, and their gas-barrier properties is presented in this article.
Abstract: Currently, there is great interest in graphene-based devices and applications because graphene has unique electronic and material properties, which can lead to enhanced material performance. Graphene may be used in a wide variety of potential applications from next-generation transistors to lightweight and high-strength polymeric composite materials. Graphene, which has atomic thickness and two-dimensional sizes in the tens of micrometer range or larger, has also been considered a promising nanomaterial in gas- or liquid-barrier applications because perfect graphene sheets do not allow diffusion of small gases or liquids through its plane. Recent molecular simulations and experiments have demonstrated that graphene and its derivatives can be used for barrier applications. In general, graphene and its derivatives can be applied via two major routes for barrier polymer applications. One is the transfer or coating of few-layered, ultrathin graphene and its derivatives, such as graphene oxide (GO) and reduced graphene oxide (rGO), on polymeric substrates. The other is the incorporation of fully exfoliated GO or rGO nanosheets into the polymeric matrix. In this article, we review the state-of-the-art research on the use of graphene, GO, and rGO for barrier applications, including few-layered graphene or its derivatives in coated polymeric films and polymer nanocomposites consisting of chemically exfoliated GO and rGO nanosheets, and their gas-barrier properties. As compared to other nanomaterials being used for barrier applications, the advantages and current limitations are discussed to highlight challenging issues for future research and the potential applications of graphene/polymer, GO/polymer, and rGO/polymer composites. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39628.
388 citations
TL;DR: The polymer-coated nanoparticles (PNPs) are an emerging class of materials that may be superior to nanoparticles for EOR due to improved solubility and stability, greater stabilization of foams and emulsions, and more facile transport through porous media as mentioned in this paper.
Abstract: Enhanced oil recovery (EOR) processes aim to recover trapped oil left in reservoirs after primary and secondary recovery methods. New materials and additives are needed to make EOR economical in challenging reservoirs or harsh environments. Nano- particles have been widely studied for EOR, but nanoparticles with polymer chains grafted to the surface—known as polymer- coated nanoparticles (PNPs)—are an emerging class of materials that may be superior to nanoparticles for EOR due to improved solubility and stability, greater stabilization of foams and emulsions, and more facile transport through porous media. Here, we review prior research, current challenges, and future research opportunities in the application of PNPs for EOR. We focus on studies of PNPs for improving mobility control, altering surface wettability, and for investigating their transport through porous media. For each case, we highlight both fundamental studies of PNP behavior and more applied studies of their use in EOR processes. We also touch on a related class of materials comprised of surfactant and nanoparticle blends. Finally, we briefly outline the major challenges in the field, which must be addressed to successfully implement PNPs in EOR applications. V C 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40576.
319 citations
TL;DR: In this article, the adsorption capacity of Fc modified cation exchange resin (FMCER) was calculated to be 392.16 mg/g Cu2+ and 10.01 mg/ g MB.
Abstract: Resin was modified with ferrocene (Fc) to enhance removal of Methylene Blue (MB) and Cu2+ from simulated wastewater. The FTIR, N2-BET, and X-ray fluorescence analysis confirmed that Fc was successfully grafted onto the surface of resin. The adsorption capacity of Fc modified cation exchange resin (FMCER) was calculated to be 392.16 mg/g Cu2+ and 10.01 mg/g MB. Both processes were spontaneous and exothermic, best described by Langmuir equation. Pseudo-first-order kinetic model satisfied the adsorption of MB, while the intraparticle-diffusion model fitted the kinetics of Cu2+ adsorption best. The result revealed a multilayer adsorption of Cu2+ on FMCER, and the kinetics maybe controlled by intraparticle diffusion, film diffusion, and competition force. The adsorption of MB and Cu2+ on FMCER were physicosorptive, with activation energies of 2.09 and 1.27 kJ/mol. pH 2–7 and 4–5 are optimum for the removal of MB and Cu2+, and pH 4 is optimal for the simultaneous removal of MB and Cu2+. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41029.
311 citations
TL;DR: A review of the molecular models of zein tertiary structure and possible mechanisms involved in zein self-assembly micro- and nano-particles are briefly introduced in this paper, and a state-of-the-art introduction and discussion are given in terms of preparation, characterization, and application of Zein-based particles as delivery systems in the fields of food science, pharmaceutics, and biomedicine.
Abstract: Zein is the major storage protein from corn with strong hydrophobicity and unique solubility and has been considered as a versatile food biopolymer. Due to the special tertiary structures, zein can self-assemble to form micro- and nano-particles through liquid–liquid dispersion or solvent evaporation approaches. Zein-based delivery systems have been particularly investigated for hydrophobic drugs and nutrients. Recently, increasing attention has been drawn to fabricate zein-based advanced drug delivery systems for various applications. In this review, the molecular models of zein tertiary structure and possible mechanisms involved in zein self-assembly micro- and nano-particles are briefly introduced. Then, a state-of-the-art introduction and discussion are given in terms of preparation, characterization, and application of zein-based particles as delivery systems in the fields of food science, pharmaceutics, and biomedicine. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40696.
233 citations
TL;DR: In this paper, a special application of the particular chemical recycling route that converts polymers into carbon-based nanomaterials is discussed, where the authors take advantage of the high carbon content of waste polymers, as well as of their high energy content, to achieve a cost-effective, environmentally-friendly, and self-sustaining production of carbon nano-materials.
Abstract: Polymer production and utilization are currently widespread and have greatly improved people's standards of living. However, due to their stable and nonbiodegradable nature, postconsumer polymers pose challenging issues to the environment and ecosystems. Efforts are being made not only to contain the generation of polymer wastes and associated littering but, also, to find ways of utilizing them sustainably. Aside from mechanical recycling, which turns postconsumer polymers into new polymer products, and thermal recycling, which releases the thermal energy contained within waste plastics through combustion, chemical recycling converts waste polymers into feedstock for chemicals/materials/fuels production. This manuscript reviews prior work on a special application of the particular chemical recycling route that converts polymers into carbon-based nanomaterials. These materials feature extraordinary physical and chemical properties with tremendous applications potential. However, their production processes are both resource- and energy-intensive. Yet, by taking advantage of the high carbon content of waste polymers, as well as of their high energy content, a cost-effective, environmentally-friendly, and self-sustaining production of carbon nanomaterials can be achieved. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39931.
205 citations
TL;DR: A review of processes, conditions and polymer systems that have been employed over the past 15 years to achieve increasingly higher cell densities and expansion ratio, culminating with the recent development of low density nanofoams and of nanostructured polymers in which nucleation can be precisely controlled as mentioned in this paper.
Abstract: Polymeric nanocellular foams are broadly defined as having cell size below one micron. However, it is only when cell size reaches 100 nm or less that unique thermal conductivity, dielectric constant, optical or mechanical properties are expected due to gas confinement in the cells or polymer confinement in the cell walls. Producing such materials with low density by physical foaming with CO2 requires the controlled nucleation and growth of 10 15 -10 16 cells/cm 3 . This is a formidable challenge that necessitates new foaming strategies. This review provides a description of processes, conditions and polymer systems that have been employed over the past 15 years to achieve increasingly higher cell densities and expansion ratio, culminating with the recent development of low density nanofoams and of nanostructured polymers in which nucleation can be precisely controlled. Remaining barriers to scale-up are summarized.
166 citations
TL;DR: In this paper, the authors summarize advancements in processes and technologies for the synthesis of polymers from various kinds of vegetable oils and highlight the advantages and disadvantages of these biobased polymers with respect to traditional monomer-based ones.
Abstract: The utilization of renewable resources for the preparation of new materials is an alternative option for reducing the high demand of fossil feedstocks. Vegetable oils are potential bioresources that are renewable and abundantly available. Triglyceride-based vegetable oils, such as soybean, jatropha, linseed, sunflower, palm, castor, nahar seed, and canola oil, are being considered as precur- sors in the production of polymers. In this article, we attempt to summarize advancements in processes and technologies for the syn- thesis of polymers from various kinds of vegetable oils. The advantages and disadvantages of these biobased polymers with respect to traditional monomer-based ones are also highlighted. V C 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40787.
150 citations
TL;DR: Wang et al. as discussed by the authors improved the adsorption capacity of the PVA hydrogel by using amphiphilic graphene oxide to improve its macromolecular chain mobility in crystal domain and introduce new functional groups.
Abstract: Because of highly frozen macromolecule chains, polyvinyl alcohol (PVA) hydrogels have never been used for dye removal. This work focuses on improving the adsorption capacity of the PVA hydrogel by using amphiphilic graphene oxide to improve its macromolecular chain mobility in crystal domain and introduce new functional groups. To evaluate its effectiveness, crystal structure, swelling kinetics, and model dye methylene blue (MB) adsorption of the as-prepared PVA hybrid hydrogels were systematically inves- tigated. The results indicate that the hybrid PVA hydrogels have lower crystallinity and less crystal stability, demonstrating the improved macromolecular chain mobility. Moreover, improved swelling ratios of PVA/GO hydrogels also illustrate the enhanced mac- romolecular chain mobility. MB adsorption experiment indicates that GO introduced can result in great improvement in MB adsorp- tion. And the adsorption process follows the second-order kinetic model and Morris-Weber model, which is determined by the intraparticle diffusion. Furthermore, MB adsorption isotherm follows Freundlich model and the adsorption is heterogeneous. Desorption studies indicate that the interaction between PVA hydrogels and MB consists of both physisorption and chemisorption. V C 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39872.
150 citations
TL;DR: A review of green polycarbonates can be found in this paper, where the authors provide a useful tool for the researchers who are new to this field, as well as an updated overview for those who are already actively working on this topic.
Abstract: Polycarbonates can be prepared by the copolymerization of epoxides with carbon dioxide as an inexpensive, abundant, nontoxic, and renewable feedstock. This review covers the synthesis, the physicochemical properties, and the growing applications of this class of green polymers. The review has been conceived to provide a useful tool for the researchers who are new to this field, as well as to offer an updated overview for those who are already actively working on this topic. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41141.
TL;DR: This review summarizes recent development in the fabrication of antibacterial nanofibers, the release profiles of the biocides and their applications in in vivo systems.
Abstract: Electrospinning is an economical and relatively simple method to produce continuous and uniform nanofibers from almost any synthetic and many natural polymers. Because of the high specific surface area, tunable pore size, and flexibility, the nanofibrous membranes are finding an increasingly wide range of applications. Some particular attention has been devoted to antibacterial nanofibers for applications such as wound dressings. A variety of biocides, e.g., antibiotics, quaternary ammonium salts, triclosan, biguanides, (silver, titanium dioxide, and zinc oxide) nanoparticles and chitosan have been incorporated by various techniques into nanofibers that exhibit strong antibacterial activity in standard assays. However, the small diameters of the nanofibers also mean that the incorporated biocides are often burst released once the materials are submerged in an aqueous solution. Nevertheless, several strategies, such as core-sheath structure of the nanofiber, covalent bonding of the biocide on the fiber surface and adsorption of the biocide in nanostructures, can be utilized to sustain the release over several days. This review summarizes recent development in the fabrication of antibacterial nanofibers, the release profiles of the biocides and their applications in in vivo systems. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40797.
TL;DR: In this article, a hyperbranched derivative of triazine group (EA) was synthesized by elimination reaction between ethylenediamine and cyanuric chloride, and the different-mass-ratio EA and ammonium polyphosphate (APP) were mixed and blended with polypropylene (PP) in a constant amount (25%) to prepare a series of EA/APP/PP composites.
Abstract: A hyperbranched derivative of triazine group (EA) was synthesized by elimination reaction between ethylenediamine and cyanuric chloride. The different-mass-ratio EA and ammonium polyphosphate (APP) were mixed and blended with polypropylene (PP) in a constant amount (25%) to prepare a series of EA/APP/PP composites. The component ratio effect of EA/APP on the flame-retardant property of the EA/APP/PP composites was investigated using the limiting oxygen index (LOI), vertical burning (UL-94), and cone calorimetry tests. Results indicated that the EA/APP/PP (7.50/17.50/75.00) composite with the appropriate EA/APP mass ratio had the highest LOI, UL94 V-0 rating, lowest heat release rate, and highest residue yield. These results implied that the appropriate EA/APP mass ratio formed a better intumescent flame-retardant system and adequately exerted their synergistic effects. Furthermore, average effective combustion heat values revealed that EA/APP flame retardant possessed the gaseous-phase flame-retardant effect on PP. Residues of the EA/APP/PP composites were also investigated by scanning electron microscopy, Fourier-transform infrared, and X-ray photoelectron spectroscopy. Results demonstrated that the appropriate EA/APP mass ratio can fully interact and lock more chemical constituents containing carbon and nitrogen in the residue, thereby resulting in the formation of a dense, compact, and intumescent char layer. This char layer exerted a condensed-phase flame-retardant effect on EA/APP/PP composites. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41006.
TL;DR: The slide-ring elastomer (SRM) as mentioned in this paper is a topological gel with a supramolecular architecture with topological characteristics, and it can pass along the polymer chains freely to equalize the tension of the threading polymer chains similarly to pulleys.
Abstract: A novel type of gel, called a topological gel, has been recently developed with a supramolecular architecture with topological characteristics. In the topological gel, polymer chains with bulky end groups are neither covalently crosslinked as in chemical gels nor attractively interacting as in physical gels but are topologically interlocked by figure-eight shaped crosslinks. Hence, these crosslinks can pass along the polymer chains freely to equalize the tension of the threading polymer chains similarly to pulleys; this is called the pulley effect. This concept can be applied not only to gels but also to a wide variety of polymeric materials without solvents. Then, polymeric materials with movable crosslinks are referred to as slide-ring materials (SRMs) in a wider sense. Here, we review the synthesis, structure, physical properties, and applications of topological gels and SRMs. In particular, slide-ring elastomers show remarkable scratch-proof properties for application to coating materials for automobiles, cell phones, mobile computers, golf clubs, and so on. © 2014 The Authors Journal of Applied Polymer Science Published by Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40509.
TL;DR: A review of current and emerging applications of pullulan within the food packaging sector is presented in this paper, where the functional proper-ties of interest for food packaging industry are discussed in light of the physicochemical attributes of this exopolysaccharide.
Abstract: Societal and industrial demands for lower environmental impact, cost effectiveness, and high-performance goods and serv- ices are increasingly impacting the choice of technologies which are developed and deployed in consumer products. Like many other sectors, food packaging is moving to new technologies; the use of biopolymers is one of the most promising strategies toward an optimized use of traditional packaging materials (e.g., oil-based plastics) without impairing the goal of extending shelf life. Among other food packaging materials, pullulan is attracting much attention due to its unique features. The goal of this review is to provide an overview of current and emerging applications of pullulan within the food packaging sector. In particular, the functional proper- ties of interest for the food packaging industry will be discussed in light of the physicochemical attributes of this exopolysaccharide. Future challenges that may dictate the successful penetration of pullulan in the food packaging market are also outlined. V C 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40539.
TL;DR: A strong antimicrobial activity against Escherichia coli of Cu-BTC metal-organic frameworks immobilized over cellulosic fibers is reported in this paper, where the in situ synthesis of MOF-199 or HKUST-1 is carried out by exposing carboxymethylated substrates to Cu(OAC)2, 1,3,5-benzenetricarboxylic acid and trie- thylamine solutions following a very specific order.
Abstract: A strong antimicrobial activity against Escherichia coli of Cu-BTC metal-organic frameworks immobilized over cellulosic fibers is hereby reported. The in situ synthesis of Cu-BTC metal-organic frameworks, aka MOF-199 or HKUST-1, onto cellulosic substrates was carried out by exposing carboxymethylated cellulosic substrates to Cu(OAC)2, 1,3,5-benzenetricarboxylic acid and trie- thylamine solutions following a very specific order. Using an in vitro model, in accordance to ASTM E2149-13a, we observed that the cellulose-MOF system was able to completely eliminate the growth of E. coli on agar plates and liquid cultures. The antibacterial activity of the comprising components of MOF-199 and the cellulosic substrate was also evaluated and determined to be negligible. Since the method used to synthesize MOF-199 crystals provides a strong bond between the crystals and the cellulosic substrates, the crystals not detach from the anionic cellulosic fibers allowing the modified textile to be washed and reused hence opening a new avenue to fabricate antibacterial clinical fabrics. V C 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40815.
TL;DR: In this paper, the ZIF-11/PBIO composite membranes were characterized and tested by gas separation and improved H2 and CO2 permeabilities with a H2/CO2 ideal selectivity of 5.6 were obtained on the 16.1 wt % ZIF11/pBI composite membrane prepared with DMAc as the solvent.
Abstract: Zeolitic imidazolate framework (ZIF)-11 crystals were prepared by the toluene-assisted method, and they were incorporated into polysulfone, polyethersulfone, and polybenzimidazole (PBI) matrix to investigate the compatibility. ZIF-11 had a good connection with PBI matrix as they had the same benzimidazole groups. The evaporation temperature of the membrane formation was studied with two different solvents: N-methyl-2-pyrrolidone (NMP) and N,N-dimethylacetamide (DMAc). Then, the ZIF-11/PBI composite membranes prepared using NMP or DMAc as the solvent were characterized and tested by gas separation. Improved H2 and CO2 permeabilities with a H2/CO2 ideal selectivity of 5.6 were obtained on the 16.1 wt % ZIF-11/PBI composite membrane prepared with DMAc as the solvent. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41056.
TL;DR: In this paper, a flame retardant tri-(phosphaphenanthrene-(hydroxyl-methylene)-phenoxyl)-1, 3, 5-triazine (Trif-DOPO) and its control samples are incorporated into diglycidyl ether of bisphenol-A (DGEBA) and 4, 4′-diamino-diphenyl sulfone (DDS) to prepare flame-resilient thermosets, respectively.
Abstract: A flame retardant tri-(phosphaphenanthrene-(hydroxyl-methylene)-phenoxyl)-1, 3, 5-triazine (Trif-DOPO) and its control samples are incorporated into diglycidyl ether of bisphenol-A (DGEBA) and 4, 4′-diamino-diphenyl sulfone (DDS) to prepare flame retardant thermosets, respectively. According to the results of limited oxygen index (LOI), UL94 vertical burning test and cone calorimeter test, the Trif-DOPO/DGEBA/DDS thermoset with 1.2 wt % phosphorus possesses the LOI value of 36% and UL94 V-0 flammability rating, and Trif-DOPO can decrease the peak of heat release rate (pk-HRR) and reduce the total heat release (THR) of thermosets. All these prove better flame retardant performance of Trif-DOPO than that of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide(DOPO). The residue photos of thermosets after cone calorimetry test disclose that Trif-DOPO can promote the formation of thick and tough melting char layer for combined action of the flame retardant groups of Trif-DOPO. The results from thermo gravimetric analysis (TGA) and pyrolysis-gas chromatography-mass spectrometry(Py-GC/MS) show that the groups in Trif-DOPO can be decomposed and produce PO2 fragments, phosphaphenanthrene and phenoxy fragments, which can jointly quench the free radical chain reaction during combustion. Therefore, the excellent flame retardancy of Trif-DOPO is attributed to its flame retardant group-synergic-effect. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39709.
TL;DR: In this article, the authors describe fabrication, function, and performance of thin-film, flexible, variable-emittance (V-E) electrochromic skins that use a conducting polymer/Au/microporous membrane (CP/au/µP) base, and a new, unique ionic liquid electrolyte (IonEl).
Abstract: Variable emittance (e) is a property vital for the increasing needs in thermal control of future microspacecraft. This article describes fabrication, function, and performance of thin-film, flexible, variable-emittance (V-E) electrochromic skins that use a conducting polymer/-Au/-microporous membrane (CP/Au/µP) base, and a new, unique ionic liquid electrolyte (IonEl). Poly(aniline-co-diphenyl amine) with a long-chain polymeric dopant is used as the CP. A unique, patented device design yields no barrier between the active, electrochromic CP surface and the external environment, except for a thin, infrared-transparent semiconductor/polymer film that lowers solar absorptance [α(s)] and protects from atomic-O/far-UV. Use of the IonEl requires special activation methods. Data presented show tailorable e variations from 0.19 to 0.90, Δe values of >0.50 (which is the highest reported thus far for any functional V-E material, to our knowledge), α(s) 7 months under space conditions (<10−5 Pa vacuum, far-UV), show excellent durability. Other data show resistance to solar wind, atomic-O, electrostatic discharge, and micrometeoroids. These lightweight, inexpensive, advanced polymeric materials represent the only technology that can work with micro- (<20 kg) and nano- (<2 kg) spacecraft, thus eventually allowing for much greater flexibility in their design and potentially “democratizing” the entire space industry, for example, allowing small firms to launch their own, dedicated satellites. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40850.
TL;DR: In this paper, ultrafiltration allows the selective extraction from industrial black liquors of lignin fraction with specific thermo-mechanical properties, which can be matched to the in...
Abstract: This study has shown that ultrafiltration allows the selective extraction from industrial black liquors of lignin fraction with specific thermo-mechanical properties, which can be matched to the in ...
TL;DR: In this article, the microstructures and miscibility at the interface between semi-crystalline and amorphous poly(l-lactic acid)(PLLA) with poly (l,d-lact acid)(PDLLA), respectively, are studied.
Abstract: The focus of this research is the study of the microstructures and miscibility at the interface between semi-crystalline and amorphous PLAs [poly (l-lactic acid)(PLLA) with poly (l,d-lactic acid)(PDLLA), respectively]. The blends are prepared through thermal processing (extrusion and hot-pressing). To increase the area of interface between PDLLA and PLLA, the fibers from PLLA and PDLLA are used. Thermal and microstructures of the blends were studied by differential scanning calorimetry (DSC), polarized optical microscopy (POM), dynamic thermogravimetric analysis(DMA), small-angle X-ray diffraction(SAXS) and wide-angle X-ray diffraction (WAXD). The two PLAs are miscible in molten state. However, phase separation is detected after various thermal treatments, with PDLLA being excluded from the regions of interlamellar PLLA regions when PDLLA content is low, as determined from X-ray diffraction studies. The compatibility between the two PLAs is not perfect in the molten state, since enthalpies of the various blends at Tg are lower than any pure PLA material. The semi-crystalline PLLA fiber can recrystallize alone in the molten amorphous PDLLA, and a higher nuclei density is observed at the interface. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41205.
TL;DR: In this paper, the steady and dynamic rheological behaviors of two cellulose nanocrystal (CNC) suspensions were investigated over a wide range of concentrations, and both CNC suspensions showed three regions in a viscosity-concentration graph.
Abstract: The steady and dynamic rheological behaviors of two cellulose nanocrystal (CNC) suspensions were investigated over a wide range of concentrations. The viscosity, storage and loss modules increased with increasing CNC concentration, and both CNC suspensions showed three regions in a viscosity-concentration graph. The two critical concentrations depended on the aspect ratio and corresponded to the overlap and gelation concentration. Because of the higher aspect ratio, switchgrass CNC suspension transitioned into a biphasic state and formed a hydrogel at lower concentrations than those of cotton CNC suspensions. Furthermore, the complex viscosities of both CNC suspensions were higher than their steady viscosities; therefore, neither CNC suspension followed the Cox–Merz rule, which may be attributed to the existence of a liquid crystal domain in each suspension. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40525.
TL;DR: A review of molecularly imprinted polymers (MIPs) with specific recognition abilities for food matrices is presented in this paper, where the authors focus on toxic and harmful substances, such as pesticide/drug residues, heavy metals, microbial toxins, and additives.
Abstract: Food security as a world issue has received increasing concern, and therefore, effective analytical methods and technologies have been continuously developed. However, the matrix complexity of food samples and the trace/ultratrace presence of targeted analytes require highly efficient cleanup and enrichment materials and procedures. Molecularly imprinted polymers (MIPs) with specific recognition abilities as versatile materials are being increasingly developed for diverse species in various fields, especially in food analysis. In this review, we mainly summarize the recent advances in MIPs used for food matrices over the last 5 years. We focus on toxic and harmful substances, such as pesticide/drug residues, heavy metals, microbial toxins, and additives. Some relatively new preparation methods involving surface imprinting, composites, and stimuli responsiveness are reviewed. Different MIPs as solid-phase adsorbents in solid-phase extraction, solid-phase microextraction, matrix solid-phase dispersion, stirring bar sorptive extraction, and magnetic material extraction and as stationary phases in chromatographic separation for foodstuff have been comprehensively summarized. MIP-based biomimetic sensing and enzymelike catalysis receive special attention. Moreover, some limitations and comparisons related to MIPs performances are also discussed. Finally, some significant attempts to further promote MIP properties and applications to ensure food safety are discussed. (c) 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40766.
TL;DR: In this paper, a new bio-polyol product consisting of high purity multi-hydroxy compounds was obtained by precipitation of the hydrophobic organics from the liquefied product in an aqueous solution.
Abstract: Liquefaction of sawdust was studied using glycerol and methanol as mix solvents. A new bio-polyol product consisting of high purity multi-hydroxy compounds was obtained by precipitation of the hydrophobic organics from the liquefied product in an aqueous solution. As identified by GC-MS, the dominate components in bio-polyol were glycerol, glycerol derivatives, and multiple types of sugar derivatives. By using the mass ratio of m (sawdust) : m (glycerol) = 1 : 1, the total content of multi-hydroxy compounds reached 90.84%. The hydroxyl number of the bio-polyol was 1287 mgKOH/g with a rotational viscosity of 1270 cP. Preparation of polyurethane foams using bio-polyol and isocyanate was also studied. Water was used as an environmental friendly blowing agent. The factors that influence the cell structure of foams (i.e., catalyst, dosage of blowing agent, and mass ratio of bio-polyol to PEG-400 were studied. The compressive strength of the synthesized foam was 150 Kpa, which met the requirement of Chinese specification for rigid foams. The synthesized foams were characterized by FTIR, SEM, and TG. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40096.
TL;DR: In this paper, an acid-catalyzed vapor phase esterification with maleic anhydride was used to improve the integrity and thermo-mechanical properties of fiber webs based on polyvinyl alcohol, PVA.
Abstract: Acid-catalyzed vapor phase esterification with maleic anhydride was used to improve the integrity and thermo-mechanical properties of fiber webs based on poly(vinyl alcohol), PVA. The fibers were produced by electrospinning PVA from aqueous disper- sions containing cellulose nanocrystals (CNCs). The effect of esterification and CNC loading on the structure and solvent resistance of the electrospun fibers was investigated. Chemical characterization of the fibers (FTIR, NMR) indicated the formation of ester bonds between hydroxyl groups belonging to neighboring molecules. Thermomechanical properties after chemical modification were analyzed using thermal gravimetric analysis, differential scanning calorimetry, and dynamic mechanical analysis. An 80% improve- ment in the ultimate strength was achieved for CNC-loaded, crosslinked PVA fiber webs measured at 90% air relative humidity. Besides the ultra-high surface area, the composite PVA fiber webs were water resistant and presented excellent mechanical properties. V C 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40334.
TL;DR: In this article, a novel approach to compatibilize Kraft lignin with polyethylene that involves the use of modified poly (styrene-co-ethylene-co butylene-co styrene) (SEBS) as unreactive compatiblizers was presented.
Abstract: This article presents a novel approach to compatibilize Kraft lignin with polyethylene that involves the use of modified poly (styrene-co-ethylene-co-butylene-co-styrene) (SEBS) as unreactive compatibilizers. As SEBS shows no compatibilizing effect on Kraft lignin-polyethylene composites, SEBS was functionalized via nitration followed by amination to obtain nitrated (SEBS-NO2) and aminated (SEBS-NH2) SEBS. The compatibilizing effects of SEBS derivatives were studied by means of morphological and mechanical analyses. The results show that SEBS-NO2 is less effective than SEBS-NH2, the later displaying comparable compatibilizing efficiency to a commercial reactive compatibilizer based on maleated polyethylene. Overall, compatibilization was found to decrease lignin particle size. Addition of SEBS-NH2 varying between 1% and 10% improved the tensile strength of composites by up to 96%, elongation at break by up to 64%, and impact strength by up to 48%. Finally, the crystallinity and density of the resulting composites were also studied. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41040.
TL;DR: In this article, two driving modes, in-plane switching and vertical field switching, have been developed to realize the electro-optic effect of polymer-stabilized blue phase liquid crystals (PS-BPLC).
Abstract: Polymer-stabilized blue phase liquid crystals (PS-BPLC) have become an increasingly important technology trend for information display and photonics applications. BPLCs exhibit several attractive features, such as reasonably wide temperature range, submillisecond gray-to-gray response time, no need for alignment layer, optically isotropic voltage-off state, and large cell gap toler- ance. However, some bottlenecks such as high operation voltage, hysteresis, residual birefringence, charging issues due to the large capacitance, and relatively low transmittance remain to be overcome before their widespread applications can be realized. Recent pro- gress on BPLC materials and devices has shown great promise. To realize the electro-optic effect of PS-BPLC, two driving modes: in- plane switching and vertical field switching mode, have been developed. The material system of PS-BPLC, including nematic LC host, chiral dopant, and polymer network, are discussed. Each component plays an essential role affecting the stability and electro-optic properties of PS-BPLC. V C 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40556.
TL;DR: In the presence of a magnetic field, the presented MAEs exhibit a strong magneto-induced change in storage modulus resulting in a colossal magnetorheological effect of >106 % which is ∼30 times higher than previously reported values as discussed by the authors.
Abstract: Highly compliant elastomers with a shear storage modulus as low as 25 Pa are prepared using commercially available silicone, plasticizer, and tactile mutator silicone additive. They are used as matrix material for magneto-active elastomers (MAEs) with carbonyl iron contents between 0 and 85 wt %. In the absence of an external magnetic field, the storage modulus of MAEs based on two selected mixtures ranges between ∼100 Pa and ∼2000 Pa. Addition of a mutator to the matrix mixture results in a long post-cure period depending on the curing temperature and the initial mixture. In the presence of a magnetic field, the presented MAEs exhibit a strong magneto-induced change in storage modulus resulting in a colossal magnetorheological effect of >106 % which is ∼30 times higher than previously reported values. The results are of interest in applications using such elastomers as cell substrates with magnetically tunable rigidity. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39793.
TL;DR: In this paper, the three components of bio-nanocomposites can be easily mixed in controlled conditions enabling the formation of thick films with high quality, smooth surface and good flexibility.
Abstract: Bio-nanocomposite films based on chitosan/polyvinylpyrrolidone (CS/PVP) and graphene oxide (GO) were processed using the casting/evaporation technique. It has been found that the three components of bio-nanocomposites can be easily mixed in controlled conditions enabling the formation of thick films with high quality, smooth surface and good flexibility. Structural and morphological characterizations showed that the GO sheets are well dispersed in the CS/PVP blend forming strong interfacial interactions that provide an enhanced load transfer between polymer chains and GO sheets thus improving their properties. It has been found that the water resistance of the CS/PVP blend is improved, and the hydrolytic degradation is limited by addition of 0.75 and 2 wt % GO. The modulus, strength, elongation and toughness of the bio-nanocomposites are together increased. Herein, the steps to form new bio-nanocomposite films have been described, taking the advantage of the combination of CS, PVP and GO to design the aforementioned bio-nanocomposite films, which allow to have extraordinary properties that would have promising applications as eventual packaging materials. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41042.
TL;DR: The latest polymerization techniques for preparing well-defined functional aliphatic polycarbonates, as well as the new applications of those aliphatics, esecially in the biomedical field are summarized.
Abstract: Aliphatic polycarbonates were discovered a long time ago, with their conventional applications mostly limited to low molecular weight oligomeric intermediates for copolymerization with other polymers. Recent developments in polymerization techniques have overcome the difficulty in preparing high molecular weight aliphatic polycarbonates. These in turn, along with new functional monomers, have enabled the preparation of a wide range of aliphatic polycarbonates with diverse chemical compositions and structures. This review summarizes the latest polymerization techniques for preparing well-defined functional aliphatic polycarbonates, as well as the new applications of those aliphatic polycarbonates, esecially in the biomedical field.