Investigation and modelling of damping mechanisms of magnetorheological elastomers

Damping in MREs is considered to be ascribed to viscous flow of the rubber matrix, interfacial damping at the interface between the magnetic particles and the matrix and magnetism induced damping. In this study, individual components in MREs that contribute to material damping were investigated. A model was developed to include viscous flow of the rubber matrix, interfacial damping and magnetism induced damping to give the total damping capacity of MREs ( )It was found that depends on frequency, iron sand content, strain amplitude and is independent of the applied magnetic field over saturation magnetization. The proposed model was assessed experimentally using a series of isotropic and anisotropic MREs. Comparison between tan δ with showed that matched the experimental trends with average percentage difference of 8.1% and 21.8% for MREs with modified iron sand unmodified iron sand, respectively. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43247.     

Synthesis of aminated glycidyl methacrylate grafted rice husk and investigation of its anion‐adsorption properties

In this study, we focused on the synthesis, characterization, and adsorption capacity testing of aminated glycidyl methacrylate grafted rice husk (RH‐g‐GMA–Am). Our goal was to obtain a high‐performance surface for the adsorption of various anions. Glycidyl methacrylate grafted rice husk (RH‐g‐GMA) was prepared by the graft copolymerization of glycidyl methacrylate with rice husk; the product was further subjected to an amination reaction. The surface properties, sorption characteristic functional groups, isotherm and kinetic studies, pore diffusion models, and effects of the temperature and pH on the material properties were studied under batch conditions. The IR spectroscopy results show additional surface functional groups for RH‐g‐GMA–Am. The adsorptions of and on RH‐g‐GMA–Am were found to follow pseudo‐second‐order kinetics; this indicated a possible dominant role played by chemisorption. The rate‐limiting step for mass transfer was found to be boundary layer diffusion. Furthermore, the sorption isotherms for and fit the Langmuir model. The amination of RH‐g‐GMA drastically increased the removal efficiency from 3 to 82% and from 6 to 93% for and , respectively. Moreover, RH‐g‐GMA–Am exhibited a better removal efficiency in the pH range of 4–6.5. Regeneration studies revealed that the surface of RH‐g‐GMA–Am could be regenerated repetitively by simple acid washing with an insignificant decrease in the active surface for consecutive adsorptions. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43002.     

Heat‐ and light‐induced thiol‐ene oligomerization of soybean oil‐based polymercaptan

Polymercaptanized soybean oil (PMSO), the product of a thiol‐ene reaction between soybean oil and hydrogen sulfide, is a material of interest as a lubricant additive and polymer precursor. We investigated with gel permeation chromatography, nuclear magnetic resonance (one‐dimensional and two‐dimensional), gas chromatography–mass spectrometry, and viscometry the changes that occur with PMSO upon heating or ultraviolet irradiation. The observed changes were due to a further thiol‐ene reaction between the thiol groups and the residual unsaturation. The formation of oligomers was a result of new sulfide bridges. Additionally, tetrahydrothiophene moieties were detected. An almost linear increase of the average molecular weight (MW) and the polydispersity index (PDI) was observed upon heat treatment [number‐average MW ( ) = 1180 Da, PDI = 1.32 for PMSO, = 1720 Da, PDI = 2.17 for PMSO that was heated for 1000 h at 130 °C]. PDI correlated best with the z‐average MW. The was the best predictor of the viscosity. For samples with close , the higher PDI corresponded to a higher viscosity index. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46150.     

Copolymers from methyl methacrylate and butyl acrylate with hyperbranched architecture

This is a first report of the synthesis and characterization of acrylic copolymers from methyl methacrylate (MMA) and butyl acrylate (BA) with hyperbranched architecture. The copolymers were synthesized using a free radical polymerization (Strathclyde method) in emulsion technique. Divinyl benzene was used as the brancher which acted as a comonomer and 1‐dodecanethiol was used as a chain terminating agent. A linear copolymer from MMA and BA was also synthesized for comparison. The hyperbranched architecture was established from spectroscopic and rheological measurements. The gel permeation chromatography showed all hyperbranched copolymers were low molecular weight with lower polydispersity index (PDI) ( 23,000, PDI ～ 2.00) compared to the linear grade ( 93,000, PDI ～ 2.20). They were more spherical and achieved lower viscosity (yet higher solubility, >90%) than the linear grade (<50%) which was mostly open ended. Lower viscosity at equivalent solid content made the hyperbranched polymers a potential binder for adhesive and coating application. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45356.     

Compressive shape memory behavior of spring‐shaped polylactic acid alloy type

This article presents an experimental study on the shape memory behavior of blends of thermoplastic polyurethane (TPU) and biodegradable polylactic acid (PLA) at the PLA/TPU weight ratios of 70/30 (PT7030) and 50/50 (PT5050). The manufactured springs were studied comprehensively based on their morphological and thermal properties. Scanning electron microscopy micrographs were captured, which verified that TPU was compatible with PLA. The wide‐angle X‐ray diffraction suggested that the crystallinity of PLA was enhanced in the presence of TPU. In order to determine the shape recovery properties [shape recovery ratio (R_r), shape fixing ratio (R_f), and shape recovery force (F_r)], the samples programmed at three different temperatures (T_p) of 70, 80, and 90 ° and at various recovery temperatures (T_r) over 40 to 90 ° , were studied. In general, the spring made with PT7030 showed higher R_r, R_f, and F_r values. The highest R_r (99%) was obtained at programmed temperature (T_p) of 70 ° and recovery temperature (T_r) of 90 ° . However, the R_r value for this spring programmed at 70 ° and recovered near body temperature was 50% with F_r of 1.4 N. Furthermore, the highest F_r (15.6 N) was observed in the spring made of PT7030 programmed at 80 ° and recovered at T_r of 78 ° . © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45115.     

Preparation of nonwoven mats of electrospun poly(lactic acid)/polyaniline blend nanofibers: A new approach

The preparation of nonwoven mats of electrospun poly(lactic acid)/polyaniline (PANI) blend nanofibers faces some critical challenges that will be addressed in the present work. The challenges are in achieving high and adjustable content of PANI while keeping the spinnable solution nonagglomerated with no need to further filtration that might lead to wrong estimation of PANI content in the mat. We report an unprecedented content of 40% wt of PANI that is achieved using a new two‐step procedure. It is based on: (1) the preparation of the spinnable solution from a friable nonagglomerated and readily dispersible PANI: ‐TSA powder and (2) the use of an optimized mixture of ‐cresol/dichloromethane. The obtained nanofiber mats are characterized by FTIR and UV–vis spectroscopy. The morphology and the thermal stability of the nanofibers are investigated by scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). The amorphous structure of the nanofibers is verified using XRD measurements. The DC‐conductivity of these blend nanofibers is found to be far larger than the published DC‐conductivity values for blend nanofibers of PANI with PLLA or with other polymers. This is attributed to the high content of PANI in the blend and to the role played by ‐cresol as a secondary dopant. The investigation of the aging effect on the DC‐conductivity reveals an exponential decrease with a characteristic time of weeks. The electrical impedance spectroscopy (EIS) shows a pure ohmic behavior of the blend mat. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43687.     

Controlling micro‐ and nanofibrillar morphology of polymer blends in low‐speed melt spinning process. Part I. Profiles of PLA/PVA‐filament parameters along the spinline

The profiles of PLA/PVA filament parameters (e.g., temperature, velocity, tensile stress, and apparent elongational viscosity) along the spinline in the low‐speed melt spinning process under various spinning conditions were investigated. Owing to the combination of the filament velocity and filament temperature measurements using laser doppler velocimetry (LDV) and infrared thermography, respectively, the fiber formation zone was determined. The length of the fiber formation zone obtained from filament velocity profiles is always shorter than that obtained from the filament temperature profiles ( . Obviously, this unexpected phenomenon occurs for low spinning speeds due to the axial heat conduction effect of the filament along the spinline and the nonuniform radial temperature distribution through the cross‐sectional thick filament. Another remarkable finding is related to the Nusselt number which has been found as nearly constant along the spinline in the low‐speed melt spinning process. Thus, mathematical simulations of the filament temperature profiles will be simplified drastically. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44258.     

Effect of K0.5Na0.5NbO3 filling particles on the charge carrier trap distribution of polyimide films

Polyimide (PI) films filled with K_0.5Na_0.5NbO₃ (KNN50) particles at different weight 0, 5, 10, and 15 wt % had been prepared by in‐situ dispersion polymerization process. The thermally stimulated current (TSDC) method was used to investigate the charge carrier trap levels and their distribution of the composite films. The TSDC spectra show that pure film has ‐peaks and ‐peak, but the composite films only have ‐peaks and an extraordinary peak at high temperature region. The trap parameters were calculated by an approximate model, and the results indicate that charge released of the shallow traps show a nonlinear behavior. The trap energies decrease from 0.879–0.968 eV to 0.549–0.839 eV with the increase of the KNN50 content. The surface and interface between KNN50 and PI matrix was considered to the variation of the trap levels. The extraordinary peak of the composite films was correlated with the phase transition of the KNN50 particles. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39828.     

Mechanism of internal and external electron donor effects on propylene polymerization with MgCl2‐supported Ziegler–Natta catalyst: New evidences based on active center counting

Two TiCl₄/Di/MgCl₂ type supported Ziegler–Natta catalysts were prepared by loading dibutylphthalate or dicyclopentyldimethoxysilane (DCPDMS) (internal donor, Di) and TiCl₄ on activated δ‐MgCl₂ in sequence, and a blank catalyst was prepared by loading TiCl₄ on the same δ‐MgCl₂ without adding Di. These catalysts have similar specific surface area and pore size distribution, thus form a suitable base for comparative studies. Propylene polymerization with the catalysts was conducted in n‐heptane slurry using triethylaluminum (TEA) as cocatalyst, and the effects of Di as well as De (external donor, in this work it was DCPDMS) on the number of active centers, the distribution of active centers among three polypropylene (PP) fractions (isotactic, medium isotactic, and atactic PP chains), and chain propagation rate constants of the PP fractions were studied by counting the number of active centers in the PP fractions using a method based on selective quench‐labeling of the propagation chains by 2‐thiophenecarbonyl chloride. When De was not added in the polymerization, introducing a phthalate type Di in the catalyst evidently changed the active center distribution by enhancing the proportion of active centers producing isotactic PP (iPP) ( ), but scarcely changed reactivities of the three groups of active centers forming the three fractions. When the De was added in the polymerization system with TiCl₄/phthalate/MgCl₂ catalyst, further shifting of active center distribution in favor of took place, meanwhile reactivities of the three groups of active centers also remarkably changed in favor of . Mutual effects of these changes led to overwhelming dominance of iPP production in the TiCl₄/Di/MgCl₂–TEA/De system (Di = phthalate, De = alkoxysilane). In contrast, though using alkoxysilane as Di also caused shifting of active center distribution in favor of when De was not added, addition of alkoxysilane De caused reverse shifting of active center distribution in favor of those producing PP of lower stereoregularity. This unfavorable change largely counteracted the reactivity changes in favor of caused by the De, rendering the catalytic system rather poor isospecificity. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46605.     

Synthesis and characterization of dendritic polypyrrole silver nanocomposite and its application as a new urea biosensor

Polypyrrole and its silver nanocomposite were electrochemically synthesized from aqueous solutions containing pyrrole, potassium chloride (KCl) (system A); pyrrole, KCl, and an anionic surfactant sodium dodecyl sulphate (NaDS) (system B); and pyrrole, silver nitrate, NaDS (system C). Compact and dendritic patterns were observed depending on experimental conditions. The aggregates were characterized by powder X‐ray diffraction, energy‐dispersive X‐ray spectroscopy, scanning electron microscopy, high resolution transmission electron microscopic (HRTEM), and thermal studies (TG/DTG). HRTEM studies indicate that the particle size of PPy‐Ag nanocomposite is ～30 nm. TG studies revealed that systems B and C, have different thermal behavior. Potassium ion selective electrodes were constructed using systems A, B, and C. The electrode prepared with PPy‐Ag nanocomposite showed nernstian behavior with maximum slope of 57 mV. ion‐selective electrode was also constructed for this system based on nonactin‐impregnated PVC matrix membrane. Urease enzyme was immobilized at the surface of as made ion‐selective electrode to develop urea biosensor showing good detection limit. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45705.     

Viscoelastic properties of borax loaded CMC‐g‐cl‐poly(AAm) hydrogel composites and their boron nutrient release behavior

Borax (Na₂B₄O₇, 10.5% Boron) loaded CMC‐g‐cl‐poly(AAm) hydrogel composites were prepared by in situ grafting of acrylamide on to sodium carboxymethyl cellulose in the presence of borax by free radical polymerization technique to develop slow boron (B) delivery device. The composition, morphology, and mechanical properties of synthesized composites were studied by X‐ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, texture analyser, and dynamic shear rheometer. Characterization revealed formation of borate ion ( ) from borax during polymerization reaction leading to extensive crosslinking of cellulosic chains and generation of mechanically strong composite hydrogels. Dynamic release of from the synthesized composites hydrogels followed Fickian diffusion mechanism and composites with high mechanical strength resulted in slow release of B. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43969.     

Electrical properties and the role of inhomogeneities at the polyvinyl alcohol/n‐inp schottky barrier interface

In this work, we have investigated the electrical properties of Au/n‐InP contacts with a thin layer of polyvinyl alcohol (PVA) as an interlayer. The current–voltage (I–V) and capacitance–voltage (C–V) measurements are carried out in the temperature range of 175–425 K. The Au/PVA/n‐InP Schottky structure show nonideal behaviors and indicates the presence of a nonuniform distribution of interface states. The temperature dependent interface states densities (N_SS), ideality factor and barrier height are obtained. An abnormal decrease in zero‐bias barrier height (BH) and increase in the ideality factor ( ) with decreasing temperature have been explained on the basis of the thermionic emission theory with Gaussian distribution (GD) of the BHs due to the BH inhomogeneities. The experimental I–V characteristics of Au/PVA/n‐InP Schottky diode has revealed the existence of a double GD with mean BH values of ( ) of 1.246 and 0.899 eV and standard deviation ( ) of 0.176 and 0.137 V, respectively. Consequently, the modified conventional activation energy versus plot gives and Richardson constants ( ) and the values are 1.17 and 0.71 eV and 9.9 and 6.9 A/cm² K², respectively, without using the temperature coefficient of the BH. The effective Richardson constant value of 9.9 A/cm² K² is very close to the theoretical value of 9.4 A/cm² K² for n‐InP. The discrepancy between Schottky barrier heights estimated from I–V and C–V measurements is also discussed. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39773.     

Preparation and characterization of thermo‐sensitive poly(vinyl alcohol)‐based hydrogel as drug carrier

Poly(vinyl alcohol)s (PVA) with high and low molecular weights were chemically modified by introducing acetaldehyde onto the polymer backbone to induce thermal‐responsive properties. The influence of both molecular weight ( ) and acetalization degree on the lower critical solution temperature (LCST) of thermo‐sensitive polymer was investigated. Moreover, a temperature responsive hydrogel was prepared by controlled cross‐linking of acetalized poly(vinyl alcohol) (APVA) and glutaraldehyde. As a model drug, ciprofloxacin was introduced into the prepared thermal sensitive hydrogel to reveal the drug loading and release behaviors. The structure, thermo‐sensitivity, swelling/deswelling kinetics, morphology, and drug loading/release behaviors were also investigated. The results indicated that the APVA polymer solution exhibited temperature responsivity, and APVA with high acetalization degree showed low LCST, whereas those with high PVAs showed high LCST. Meanwhile, morphology study was identical with the swelling/de‐swelling behavior. The loading and release of ciprofloxacin were controllable. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39720.     

Dispersion polymerization of methyl methacrylate with three types of comblike fluorinated stabilizers in supercritical carbon dioxide

Dispersion polymerizations of methyl methacrylate in supercritical carbon dioxide were conducted with three types of comblike fluorinate polymer stabilizers: poly(3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10‐heptadecafluorodecyl methacrylate) (PHDFDMA), poly(3,3,4,4,5,5,6,6,7,7,8,8,8‐tridecafluorooctyl methacrylate) (PTDFOMA), and poly(2,2,3,3,3‐pentafluoropropyl methacrylate) (PPFPMA). The effect of the polymerization pressure was not significant on the mean diameters of the poly(methyl methacrylate) (PMMA) particles from 20 to 40 MPa. However, the coefficients of variation of the particle diameters produced at 20 MPa ( , where is the number‐basis mean particle diameter), where the heterogeneous phase was found before polymerization, were larger than those produced at 30 and 40 MPa, where the homogeneous phase was found. The mean size of the PMMA obtained with PTDFOMA and PPFPMA strongly depended on the stabilizer concentration compared with that obtained with PHDFDMA. Moreover, the mean size decreased as the carbon dioxide‐philic side chain length increased. As shown by the results of this study, the best stabilizer among the three types of stabilizers for producing PMMA particles was PHDFDMA. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43813.     

Free volume and damping in a miscible high performance polymer blend: Positron annihilation lifetime and dynamic mechanical thermal analysis studies

High performance polymer blend of poly(ether ether ketone) (PEEK) and poly(ether imide) (PEI) was examined for their free volume behavior at different compositions of PEI using positron annihilation lifetime spectroscopy (PALS). The damping property of the blend was studied using tan‐δ obtained from dynamic mechanical thermal analysis (DMTA). The dependence of tan‐δ on temperature revealed that the blend is miscible in all compositions, in agreement with earlier studies. The tan‐δ peak height is found to increase with increase in free volume fraction for the entire blend composition signifying that the free volume plays an imperative role in understanding the damping property. Using DMTA, master curves were obtained at a reference temperature T₀ by applying the time‐temperature‐superposition (TTS) using Williams‐Landel‐Ferry (WLF) relationship. From the shift factor a_T, the WLF coefficients and were evaluated, using which the free volume fraction was found. Both PALS and DMTA methods were found to give similar results for the dependence of free volume for various PEI contents studied in this blend. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42961.     

Indirect effect of polyvinylpyrrolidone and cetyltrimethylammonium bromide on UV‐blocking efficiency of TiO2@PVP‐CTAB@SiO2 core‐shell nanohybrid particles

In this study, a novel and useful approach to fabricate @PVP‐CTAB@ (TPS) nanohybrid as an effective light stabilizer agent has been reported. Also, the indirect role of the Polyvinylpyrrolidone and cetyltrimethylammonium bromide on UV (ultraviolet) protection properties of nanohybrid particles was investigated. In addition, comparative studies were carried out to evaluate the photocatalytic and UV protection properties of @ (TS), commercial (US3490), synthesized nanparticles, and TPS nanoparticles. Furthermore, the UV protection property of 2‐(2H‐benzotriazol‐2‐yl)?4, 6‐bis (1‐methyl‐1‐phenylethyl) phenol, as an organic anti UV, was also compared with TPS nanoparticles. The as prepared nanohybrid was characterized by Fourier transform infrared spectroscopy, zeta potential, field emission scanning electron microscope (FESEM), transmission electron microscope (TEM), and UV‐Vis spectroscopy. FESEM and TEM micrographs show monodispersity and nano‐metric size of TPS. Rhodamine B degradation study clearly shows that TPS present the lowest photocatalytic property. Also, UV‐Vis spectroscopy results show that the TPS nanoparticles illustrate higher UV blocking ability comparing to other presented anti UV materials. TPS with convenient and useful synthesis method, high UV blocking ability, and little effect on polymer matrix can be introduced as a novel UV‐blocking agent in polyurethane matrix. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44148.     

Butyl rubber reclamation by combined microwave radiation and chemical reagents

Rubber recycling is growing worldwide because of increasing raw material costs. In addition, extensive use of rubber articles and their eventual disposal is a major concern for the environment. Butyl rubber (IIR) was devulcanized by microwave radiation with the aid of devulcanizing reagents and oil. The effect of several devulcanizing reagents, hexadecylamine (HAD), diphenyl disulfide (DPDS), N‐cyclohexyl‐2‐benzothiozyl sulfenamide (CBS), and tetramethylthiuram disulfide (TMTD) on devulcanization process, was studied. The investigation was carried out in various microwave radiation temperatures and different amounts of aromatic and paraffinic oils. The results showed that waste rubber powder with a median particle size of 279 was devulcanized efficiently. It was confirmed when devulcanization % of the devulcanizates were measured by swelling tests. Among of the devulcanizing reagents and based on Horix analysis, HDA with the sol fraction, crosslink density (CLD), and devulcanization percent of 14%, 25 and 64%, respectively, was the most suitable devulcanizing reagent. In addition, compound with 30 and 6 phr paraffinic oil and HDA in formulation, respectively, had maximum devulcanization % (83%). The devulcanizing temperature of this compound was 180 . For the most of all compounds, during microwave radiation, a part of disulfides crosslinks were broken and released sulfurs giving new mono and polysulfides bridges. This resulted in the higher CLDs for some compounds when they compared with CLD of the initial waste rubber. In the morphological study of the devulcanized compounds, vulcanized rubbers clearly showed in the SEM micrographs surrounded by a matrix of devulcanized rubber. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43363.     

Counterion-Induced Cationic Flexible Nanoparticle Catalytic of Piperidinolysis of Phenyl Salicylate

The removal of PSa^? from bulk aqueous phase to the pseudo‐micellar phase by halobenzoate counterion X is responsible for the monotonic increase in k_obs (pseudo first‐order rate constants) with the increase in the values of [MX] where MX = sodium salts of 2‐, and 4‐halobenzoic acids. The values of ion exchange constants, or for X = 2‐ and 4‐halobenzoate ions in the presence of tetradecyltrimethylammonium bromide (TTABr) were calculated from the apparent catalytic rate constants, ^Xk_cat which represent the catalytic effect of CFN. Larger values of or were observed for X = 4‐halobenzoate ions than that for X = 2‐halobenzoate ions due to isomeric factors. The values of or determined in the presence of TTABr were compared with previously determined or values in the presence of cetyltrimethylammonium bromide (CTABr). The values of or are nearly 8 ~ 9‐fold larger for 4‐IBz^?, 4‐BrBz^? and 4‐ClBz^? compared to the respective values of X = 2‐IBz^?, 2‐BrBz^? and 2‐ClBz^?. The values of or for X = 4‐FBz^? is nearly 3‐fold larger than that for X = 2‐FBz^?. The values of or for X = 2‐ and 4‐halobenzoates are significantly smaller in the presence of TTABr than these in the presence of CTABr nanoparticles.     

Sb‐intercalated layered double hydroxides–poly(vinyl chloride) nanocomposites: Preparation,characterization, and thermal stability

In this study, a novel ‐intercalated layered double hydroxide (Sb‐LDH) was prepared by simultaneous recovering of LDH structures and intercalation of into LDH layers. The prepared Sb‐LDH composites remain the hydrotalcite structure with layered geometry and show higher thermal property than that of LDH. When applied to poly(vinyl chloride) (PVC) composites, Sb‐LDH showed limited thermal stability for PVC at the early stage of thermal and thermooxidative degradation processes. However, Sb‐LDH could retard the thermal cracking of the carbonaceous conjugated polyene of PVC which may hinder further degradation, and the moderate amount of Sb‐LDH (1, 2, and 5 wt %) in PVC resin can retard the process of decarbonation and enhance char formation. Sb‐LDH also promoted the transparency of PVC but darkened the color. With the advantages of transparency promotion, high temperature resistance, and long‐term stability, the prepared Sb‐LDH is a potential thermal stabilizer for PVC resins. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42524.     

Morphologies of electrospun fibers of lignin in poly(ethylene oxide)/N,N‐dimethylformamide

The effects of polyethylene oxide (PEO) molecular weight (Mv), and volume fraction ( ) on the morphology of electrospun sulfur free softwood lignin nanofibers were investigated. Small amounts of PEO were used during preparations of the solutions to aid the electrospinning process. It was found that tripling the PEO volume fraction resulted in a transition from semi‐dilute un‐entangled to semi‐dilute entangled solutions. Conversely, the solution remained in the semi‐dilute un‐entangled regime as the molecular weight was increased by five times. The effects of molecular weight and volume fraction of PEO both on entanglement density and fiber morphology were unified by scaling PEO viscosities as a function of . We investigated and discussed conditions that would produce smooth fibers and conditions that would produce fibers with beads. In the case of beads‐on‐a‐string formation, bead widths remained constant regardless of the molecular weight and concentration of PEO, but the bead length changed. Additionally, we observed a decrease in the diameter of the fibers and the dimension of beads (length and width of beads) with an increase in the electric field used for electrospinning. The aspect ratio of beads increased with increases to both the electric field and the PEO molecular weight or concentration. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44172.