Correlation between the mechanical and dielectric responses in polymer films by a fractional calculus approach

A fractional calculus approach was used to study the correlation between the complex elastic modulus and the complex relative permittivity for a polystyrene (PS) film with thickness of ~80 μm. Experimental measurements were carried out using dynamic mechanical analysis and dynamic dielectric analysis. Experimental results show the mechanical and dielectric manifestations of the main relaxation (glass transition process), whose molecular mobility was analyzed by two innovative models: a mechanical fractional model and a dielectric fractional model. Parameters of fractional models show that, when temperature increases, the molecular mobility of the main relaxation also increases, but the cooperativity of mobility decreases. Besides, molecular mobility is greater in the mechanical manifestation of the main relaxation than in the electric manifestation. From theoretical results obtained from fractional models for the isochronal mechanic storage modulus, E′(T) , and the isochronal relative permittivity, , a correlation model for mechanical and dielectric properties of PS film was obtained. This correlation model describes in function of E′(T) . These results suggest that this correlation model can be used to study molecular mobility of mechanical and dielectric dynamic properties of the polymer films samples and predict changes in their behavior by modifying ambient conditions.     

Shear rheology and scaling of semiflexible polymers: Effect of polymer-solvent interactions in the semidilute regime

Semiflexible polymers and their assemblies are important in biology as cross-linked networks of semiflexible polymers form a major structural component of tissue and living cells. This research used shear rheology to demonstrate the tuning from worm-like to rod-like conformation in semiflexible polymers by polymer-solvent interactions. The conformation was assessed by the persistence length l_p, and its influence, in the semidilute regime, was assessed by the scaling of zero-shear viscosity η_o with concentration c and molecular weight . The polymers were poly n-butyl and poly n-octyl isocyanate (PBIC and POIC, respectively). PBIC exhibited the largest l_p in chlorinated solvents, and the solutions obeyed the scaling law . However, when PBIC was dissolved in benzene the l_p was greatly reduced and the scaling law now was , consistent with a worm-like conformation. On the other hand, POIC dissolved in chlorinated and benzenic solvents exhibited a worm-like conformation and the scaling was . These results were contrasted with those of hydroxypropyl cellulose (HPC) aqueous solutions, which exhibit worm-like conformation, the solutions obeyed the scaling η_o ∝ c^2.5 . Finally, the shear viscosity of the polyisocyanates and HPC obeyed the Saito scaling, valid for anisotropic particles in solution.     

Influence of gel preparation concentration on statistical mechanics of poly(dialkylaminoethyl methacrylate) gels on the basis of scaling concept: Toward tunable elasticity and thermomechanical parameters

In order to evaluate the scaling parameters of weakly cationic crosslinked network structures, poly(dialkylaminoethyl methacrylate)-based hydrogels were synthesized via free-radical crosslinking in aqueous solution varying systematically concentration of pregel solution. Based on the gel-preparation concentration, variation in structural properties, effective crosslinking density, average molecular weight of polymer chains, and thermodynamic parameters from combined swelling and elasticity results were discussed using the scaling theory to predict various exponent identities. The concentration dependence of compressive elastic modulus as-prepared state was described by a power-law relationship with the exponent of m = 3.55 indicating the importance of the trapped entanglements. Two structural characteristics, the network chain length N and the average molecular weight of polymer chains have inverse dependence on the gel-preparation concentration in the matrix, while the compressive moduli and effective crosslinking density show completely direct dependence. Experimentally determined N values of PDMAEMA hydrogels first decrease with increasing up to 0.2972 and the dependence of N on the gel-preparation concentration gives the relation with a scaling parameter n = −1.80, which coincides with the prediction of scaling theory. Acceptable agreement was found between the estimate of crosslink density fluctuations deduced from mechanical measurements and the results derived from independent swelling observations. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48350.     

Fluorosilicone resin as a high ultraviolet transmittance optical material

In this study, hydrofluorosilicone oil with a cyclic structure () and tetramethyl-tetravinylcyclotetrasiloxane () are synthesized through a hydrosilylation reaction with platinum as the catalyst to obtain high ultraviolet transmittance fluorosilicone. The curing process of fluorosilicone resin is monitored by Fourier transform infrared spectroscopy. The effects of different A values (the molar ratio of Si─H to vinyl) on the curing process, mechanical properties, glass transition temperature, crosslinking density, hydrophobicity, and UV transmittance are studied. The results demonstrate that with the increase in the A value, the initial curing temperature and the temperature at the completion of curing decrease, the tensile strength initially increases and then decreases, and the glass transition temperature and crosslinking density increase. Furthermore, the contact-angle and UV transmittance initially increase and subsequently decrease, the maximum contact-angle is 107.61°, which shows good hydrophobicity, and the maximum UV transmittance at 351 nm reaches 93.66%.     

A green resin acid ester surfactant from colophony and xylitol: Synthesis,self-assembly in nonaqueous solvents,and thermodynamics

An environmental friendly oil-soluble surfactant colophony xylitol ester (CXE) is first synthesized from natural colophony and xylitol with the use of hot-compressed water and subcritical CO₂ in a steel autoclave. In this solvent-free system, the conversion of the reaction was up to 90.30% in 4 h. Thermal gravimetric analysis determine that its thermal stability was as high as 310°C. CXE is effective in reducing the surface tension of six different organic solvents. The greatest effect of surface tension reduction by CXE is in the case of dimethyl sulfoxide, the surface tension of the surfactant solution was as low as 36.26 mN/m at its critical micelle concentration value of 7.49 mM; The greatest effect of interfacial tension reduction by CXE is in the case of turpentine and water, the interfacial tension low to 1.51 mN/m. Furthermore, transmission electron microscope and particle size measurement showed that CXE is successfully self-assembled into micelles, vesicles, and heteromorphic vesicles in six kinds of organic solvents. Finally, the critical micelle concentration curves at different temperatures provided the thermodynamic parameters of the aggregate formation, found that , , and are negative and increased as the temperature increased.     

Regeneration and utilization of waste phenolic formaldehyde resin: A performance investigation

Recycled thermosetting phenolic formaldehyde (RPF) resins were pulverized to micron-sized powders and successfully reused as an effective component by reactive-injecting with neat phenolic formaldehyde (PF) and/or trioxymethylene (TOX) to prepare regenerated phenolic formaldehyde (i.e., and ). Tensile strength (σ_f), impact strength (I_s), and density (ρ) of and specimens were reduced as RPF concentrations or average particle sizes increased. It is worth emphasizing that σ_f, I_s, and ρ of each reaction-injected series having a fixed RPF concentration and average particle size improved to a maximum value, as TOX concentrations reached a corresponding optimal value. This is the first investigation to report that σ_f and I_s of proper regenerated PF/RPF/TOX specimens using ≦20 wt % RPF waste were ≥ 95% of those of the virgin reaction-injected PF. Possible reasons accounting for these improved mechanical properties were proposed based on results from their Fourier transform infrared analysis (FTIR). © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47445.     

Kinetic study on the synergistic effect between molecular weight and phosphorus content of flame retardant copolyesters in solid-state polymerization

2-Carboxyethyl(phenyl phosphinic) acid has been proved to modify flame retardant properties of poly(ethylene terephthalate) (PET) through copolymerization; however, there is no industrial technological breakthroughs in polyester industrial yarns which requires high strength and modulus, because it is related to the coordinated control of molecular weight and flame retardancy. In this work, the influence of solid-state polymerization reaction kinetics and parameters on flame retardancy retention have been investigated, based on the prepared precursors optimized at 6,000 ppm phosphorus content and 0.64 dL/g intrinsic viscosity (I.V). Results showed that the copolyester polydispersity index increase was significant compared to PET with molecular weight increase. The I.V of optimized precursor could be increased to 1.31 dL/g at 220°C in 20 hr, but at higher phosphorus content loses up to 7%. Flame retardant component deteriorates with increasing reaction rate and temperature as a result of severe side reactions. Optimized precursor at the optimum temperature (210°C) reacted for 20 hr, copolyester with the phosphorus content of 5,910 ppm and the I.V of 1.12 dL/g (( was about 3.5 × 10⁴ g/mol) was prepared. The coordination between high molecular weight and flame retardant performance was realized.     

Synthesis,thermal, dielectric,and microwave reflection loss properties of nickel oxide filler with natural fiber-reinforced polymer composite

Fabrication of hybrid composite of nickel oxide (NiO) combined with oil palm empty fruit bunch (OPEFB) reinforced with polycaprolactone (PCL) has been done by using thermal Haake blending machine, which ensured mixture homogeneity. All hybrid composites' characterizations were carried out using X-ray diffraction (XRD), Fourier transform infrared spectrometry, differential thermogravimetry, thermogravimetric analysis, and scanning electron microscopy. The results showed that the XRD profile patterns of the composites clearly changed as the filler loading amount was increased. Fourier transform infrared spectra illustrated a slight change in the frequencies and positions of the peaks after adding NiO, indicating that some interactions occurred between C=O and O–H or among the fiber, NiO, and PCL. The microwave electromagnetic properties, such as reflection loss (dB), relative complex permittivity (ε_r =–j), and permeability (−j) were calculated at various microwave frequencies in the X-band (8–12 GHz) range. It was observed that the thermal stability, magnetic, and dielectric properties of NiO:OPEFB:PCL composites were modified significantly with NiO addition. This enables the new hybrid composites to be used as engineering materials in the microwave applications. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 46998.     

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.     

Viscoelastic properties and extrusion processability of poly(vinyl butyral)

Rheological properties and flow instability at capillary extrusion of a random terpolymer composed of vinyl butyral, vinyl alcohol, and vinyl acetate, that is denoted as PVB in this article, are studied. It is found that the rubbery plateau modulus is 1.3 MPa at 100°C from the oscillatory shear modulus. Furthermore, the average molecular weight between entanglement couplings M_e is found to be 2670. Because of the relatively high value of , it shows rubbery region in the wide temperature range (90°C–180°C). At the capillary extrusion, the surface instability (shark‐skin failure) appears prior to volumetric melt fracture. The onset stress of the shark‐skin failure, ca. 0.18 MPa, is similar to that of polyethylene, although PVB used in this study has narrow molecular weight distribution. Moreover, the apparent slippage is not detected, presumably due to good adhesion to the die wall. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40337.     

Correlation between clay type and performance of swelling inhibitors based on polyetherdiamine in aqueous fluids

In this work, the linear swelling of four samples of natural clays was evaluated, using poly(propylene glycol) bis(2-aminopropyl ether) ~230 g mol⁻¹ (PEDA-230) and ~400 g mol⁻¹ (PEDA-400) as shale inhibitors for water-based drilling fluids, in comparison to a commercial shale inhibitor. The swelling kinetics was described by a semiempirical equation. A correlation was found between the cation exchange capacity of the clays and the diffusion kinetic constant of the inhibitors. Increased molar mass of PEDA favored swelling inhibition. The swelling inhibition was also evaluated by rheology, and the results were in agreement with the linear swelling tests. Scanning electron microscopy demonstrated the occurrence of microfractures on the clay surface after water contact, as well as the adsorption of the different shale inhibitors on the clay surfaces after contact with the aqueous inhibited fluid. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47661.     

Preparation and characterization of poly(ethylene terephthalate) copolyesters modified with sodium‐5‐sulfo‐bis‐(hydroxyethyl)‐isophthalate and poly(ethylene glycol)

Two types of poly(ethylene terephthalate) (PET) copolyesters were successfully prepared with sodium‐5‐sulfo‐bis‐(hydroxyethyl)‐isophthalate (SIPE) and poly(ethylene glycol) (PEG) units with different molecular weights named as cationic dyeable polyester and easy cationic dyeable polyester. Their chemical and crystalline structures were characterized by the nuclear magnetic resonance (NMR), wide angle X‐ray diffraction (WAXD), and small angle X‐ray scattering measurement, and their thermal properties were tested by differential scanning calorimetry and thermogravimetric analysis, respectively. NMR experimental results showed that the actual molar ratio of comonomers was basically consistent with the correlative feed ratio. WAXD results indicated that the crystalline structures of prepared copolyesters were similar to that of PET. Moreover, the glass transition temperature, melting temperature, and thermal degradation temperature were found to decrease with the reduction of the of PEG units as the incorporation of lower of PEG units brought more ether bonds into molecular chains, which increased the irregularity of molecular chain arrangement and led to lower crystallinity. In addition, because the incorporation of PEG units with lower molecular weight led to more ether bonds and hydroxyl end‐groups in molecular chains, the value of contact angle of PET copolyesters dropped, manifesting PET copolyesters had better hydrophilicity with the decreasing molecular weight of PEG units.© 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39823.     

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.     

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.     

Synthesis and evaluation of an environment-friendly terpolymer CaCO3 scale inhibitor for oilfield produced water with better salt and temperature resistance

The CaCO₃ deposits exist widely in the petroleum industry, causing severe damage to the equipment and production. In this article, a novel environment-friendly terpolymer scale inhibitor Poly (maleic anhydride - acrylic acid -2- acrylamide -2- methyl propanesulfonic acid) (P(MA-AA-AMPS))-containing carboxylic acid group, sulfonic acid group, and amide group was synthesized. The structure and molecular weight were characterized by FTIR, ¹H-NMR, and GPC. The static scale inhibition experiment was conducted to study the influence of factors such as the dosage, monomer ratio, temperature, pH, Ca²⁺ concentration, and concentration on the scale inhibition performance of CaCO₃. The results show that when the monomer ratio is 2.0:1.0:0.5 and the dosage is 20 mg L⁻¹, the maximum scale inhibition efficiency is 95.52%. Even when Ca²⁺ concentration exceeds 1200 mg L⁻¹ and temperature reaches 90 °C, the scale inhibition efficiency is still larger than 80%. The results of SEM and XRD show that P(MA-AA-AMPS) interferes with the growth of CaCO₃ crystal by adsorption, dispersion, and chelation. The effect leads to changes in the morphology of CaCO₃ crystals, the size of which drops from 20–30 μm to 2–5 μm. The P(MA-AA-AMPS) can transform CaCO₃ from stable calcite crystals to unstable aragonite and vaterite. Finally, the formation of CaCO₃ scale is well inhibited. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48460.     

Correlating the mass and mechanical property changes during the degradation of PEG-based adhesive

Change in mechanical property of a degrading adhesive is critical to its performance. However, characterization of degradation behavior is often limited to tracking its mass loss. Four-armed poly(ethylene glycol) end modified with dopamine (PEG-DA) was used as a model bioadhesive to correlate its change in mass with change in mechanical property. Shear modulus (G) was calculated based on the mass and average molecular weight between crosslinks () of PEG-DA, while the storage modulus (G′) was determined by oscillatory rheometry. G decreased slowly within the first week of degradation (4% reduction by week 2), while G′ decreased by 60% during the same period. This large discrepancy is due to the partially disconnected and elastically ineffective PEG polymer, which is trapped within the adhesive network. This resulted in minimal mass change and higher calculated G value during the earlier time points. Therefore, tracking mass loss profile alone is inadequate to completely describe the degradation behavior of an adhesive. Additionally, PEG-DA was coated onto magnetoelastic (ME) sensors, and the change in the resonance amplitude of the sensor corresponded well with dry mass loss of PEG-DA. ME sensing provides a nondestructive method to track the mass loss of the coated adhesive. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48451.     

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.     

Novel anion exchange membrane with low ionic resistance based on chloromethylated/quaternized-grafted polystyrene for energy efficient electromembrane processes

A novel anion-exchange membrane has been manufactured by chloromethylation and subsequent quaternization of polystyrene within a graft copolymer films based on UV-oxidized polymethylpentene. Particular attention is given to the kinetics of chloromethylation and the influence of the reaction conditions on the properties of the anion-exchange membranes. By means of variation of the polystyrene content and its crosslinking degree we have obtained membranes that have an ion-exchange capacity from 1.1 to 2.9 mmole g⁻¹, anion transport numbers between 91.0 and 95.5% and specific ionic conductivities ( ranging from 2 to 25 mS cm⁻¹. The developed membranes due to their low thickness and high conductivities have a remarkably low surface ionic resistance of around 0.6 Ω cm². It was calculated that the use of the developed materials will increase the efficiency of reverse electrodialysis energy production by 8–10% compared to the state of the art membranes. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 137, 48656.     

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.     

Effect of Various Electrolytes on the Phase Separation and Thermodynamic Properties of p-Tert-Alkylphenoxy Poly (Oxyethylene) Ether in the Absence/Presence of Drugs

Cloud point (CP) measurements of 4-(1,1,3,3-tetramethylbutyl) phenyl-polyethyleneglycol (Triton X-100 (TX-100)) were performed in aqueous solution in the presence of drug Amikacin sulfate (AS)/Neomycin sulfate (NS)/(AS/NS+ different inorganic salts). In aqueous solution, the CP values of TX-100 first decrease with increasing concentration and then increase with increasing surfactant concentration. The CP values of TX-100 solutions were found to increase with the increasing concentration of the AS/NS drug. The CP values of TX-100-AS/NS mixtures were also observed to decrease with the increase of the concentration of salt. Different thermodynamic parameters such as standard free energy (), standard enthalpy () as well as the standard entropy () change of phase separation were calculated and discussed in relation to molecular interactions.