当前期刊: Journal of Macromolecular Science Part B-Physics Go to current issue    加入关注   
显示样式:        排序: 导出
我的关注
我的收藏
您暂时未登录!
登录
  • Non-isothermal Thermogravimetric Degradation Kinetics, Reaction Models and Thermodynamic Parameters of Vinylidene Fluoride Based Fluorinated Polymers
    J. Macromol. Sci. B. Phys. (IF 1.204) Pub Date : 2019-11-22
    Arjun Singh; Shalu Singh; Pramod Kumar Soni; Niladri Mukherjee

    Commercial fluororubber SKF 32, fluoroplastic F-32L, fluoroelastomer Kel-F, fluoroplastic FK 800 (labeled as SKF 32, F-32L, Kel-F and FK 800) and an in-house prepared poly(vinylidene fluoride-chlorotrifluoroethylene) (FKM) copolymer were investigated in terms of their thermal degradation kinetics, reaction models and corresponding thermodynamic parameters. All samples underwent a single step thermal degradation using thermogravimetric analysis (TGA) at different heating rates under nitrogen atmosphere. The kinetic parameters were determined through the Kissinger method and three isoconversional methods; viz. the Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS) and Starink. The activation energies of the SKF 32, F-32L, Kel-F, FK 800 and FKM obtained using the Kissinger method were 206, 200, 185, 221 and 243 kJ mol‒1, respectively. The activation energy values for the degradation obtained using the KAS method were: 180–225 kJ mol−1 for SKF 32, 192–209 kJ mol−1 for F-32L, 163–185 kJ mol−1 for Kel-F, 213–227 kJ mol−1 for FK 800 and 187–269 kJ mol−1 for FKM with the extents of conversion (α) = 0.1–0.9. These values of the activation energies obtained from the KAS method were in good agreement with those obtained using the FWO and Starink methods. In addition, the appropriate degradation reaction models were determined by means of the Coats-Redfern and Criado methods. The thermodynamic parameters, such as activation Gibb free energy, ΔG*, activation enthalpy, ΔH*, and activation entropy, ΔS*, for formation of the activated complexes during the thermal degradation were also determined and discussed. The positive values of the Ea, ΔG*, ΔH*, and ΔS* for SKF 32, F-32L, FK 800 and FKM indicated a non-spontaneous process, while the positive values of the Ea, ΔG* and ΔH*, and negative value of ΔS* for Kel-F meant that the formation of the activated complex was accompanied by a smaller decrease of entropy than for the other polymers.

    更新日期:2020-01-06
  • Fretting Wear Behavior of Cu/Ultra-High Molecular Weight Polyethylene Nanocomposites Under Different Strokes
    J. Macromol. Sci. B. Phys. (IF 1.204) Pub Date : 2019-11-25
    Xiaocui Xin; Yunxia Wang; Zhaojie Meng; Hao Liu; Yunfeng Yan; Fengyuan Yan

    Ultrahigh molecular weight polyethylene (UHMWPE) composites reinforced with various contents of nanometer sized particles of Cu were prepared by a hot pressing technique. The fretting wear behavior of UHMWPE and the Cu/UHMWPE nanocomposites were evaluated on an oscillating reciprocating friction and wear tester. The study focused on the effect of the Cu nanoparticle contents and the fretting strokes on the fretting wear behavior of the composites. The results showed that both the strokes and the contents of Cu nanoparticles had an influence on the tribological properties of the composites. The friction coefficients and wear rates first decreased and then increased with the increasing of Cu nanoparticles contents. The content corresponding to the lowest friction coefficient was 1.5%. When the amounts of Cu nanoparticle ranged from 0.5% to 1%, the composites showed the lowest wear rates. In general, the higher number of strokes corresponded to the lower wear rates, which were attributed to alleviated abrasion. More importantly, thin and uniform transfer films were formed on the worn surfaces of the steel balls after sliding against the 1% Cu/UHMWPE nanocomposites. Consequently, the wear rate was decreased. It was inferred that the inclusion of Cu nanoparticles is beneficial for improving the wear resistance of the composites.

    更新日期:2020-01-06
  • Physical Properties of Hot Isostatic Press Molded Poly(carboxy decanediamine)
    J. Macromol. Sci. B. Phys. (IF 1.204) Pub Date : 2019-11-11
    Yutaka Kawahara; Shunsuke Otoyama

    A fully nature-originated poly(carboxy decanediamine) (PUA10) was synthesized from pressurized carbon dioxide and 1,10-decanediamine, which acted as the monomers. Hot isostatic press (HIP)-molding was attempted using powdered PUA10 sample, and the crystal structure as well as physical properties of the molded specimens were investigated. The crystal structure of PUA10 was found to be more perfect after HIP-molding, which is most likely related to the crystallization that occurs under the pressurized conditions. PUA10 crystals generated at atmospheric pressure showed a Brill transition-like crystal phase transition at 145 °C and had a melting temperature of 225 °C. To the contrary, PUA10 crystals generated via the HIP-molding melted at 250 °C. The HIP-molded PUA10 specimen had a compressive yield stress greater than 110 MPa, which is greater than those of various polyamide (PA) polymers. However, the coefficient of thermal expansion (CTE) of HIP-molded PUA10 at around 100 °C was about 30.3 × 10−5 K−1, which is much larger than the CTEs of PA6 and PA66 (10–14 × 10−5 K−1) in the same temperature range.

    更新日期:2020-01-06
  • Preparation of Polyvinyl Alcohol/Ninhydrin Blend Nanomembranes by Needleless Electrospinning and Their Application in Latent Finger Mark Detection
    J. Macromol. Sci. B. Phys. (IF 1.204) Pub Date : 2019-11-06
    Yi-Ting Wang; Ying Wang; Jing Guo; Qian-Xi Zhou

    Finger mark identification, which is one of the biological recognition methods, has a history of more than 100 years. In this study, polyvinyl alcohol (PVA)/ninhydrin blend nanomembranes were prepared using needleless electrospinning and applied in latent finger mark detection. The morphology and structure of the PVA/ninhydrin nanomembranes were investigated using scanning electron microscopy, Fourier transform infrared spectroscopy and X-ray diffraction. The results showed that the preferable composition for the best spinnability of the complex solution was 86.9 g/L PVA and 76.1 g/L ninhydrin, using water as solvent. The ninhydrin was uniformly dispersed in the PVA/ninhydrin nanomembranes in the amorphous regions. There was a small amount of hydrogen bonds between the PVA and ninhydrin. The addition of ninhydrin did not affect the crystal structure of PVA. When subjected to hot steam of a weak acidic water bath (pH = 6), the PVA/ninhydrin nanomembranes completely displayed the latent invisible finger marks left on glass or ceramic surfaces in purple within 3–5 min of the steam exposure, which were easily observed by the naked eyes. The purple finger marks on the nanomembranes were due to the reaction of ninhydrin with amino acids in sweat released from the fingers. Both chemical cross-linking and physical adhesion of the membrane to the surface occurred in the area of the finger mark regions. Physical adhesion also developed in the regions without finger marks. Therefore, finger marks identification using electrospun PVA/ninhydrin nanomembranes is simple, rapid, harmless, and sensitive, and does not need large instruments or any type of liquid chemical reagent.

    更新日期:2020-01-06
  • Cellulose Acetate/Activated Carbon Composite Membrane with Effective Dye Adsorption Performance
    J. Macromol. Sci. B. Phys. (IF 1.204) Pub Date : 2019-09-26
    Xiaoyan Zhao, Chen Huang, Shuai Zhang, Chenyi Wang

    Cellulose acetate (CA) and activated carbon (AC) were used as base material and additive, respectively, to prepare CA/AC composite membranes. By adjusting the AC content (5%, 10%, 15%, and 20%), the morphology and the adsorption capability of the samples for target dyes were studied. The results showed that the surface flatness and compactness of the barrier layer deteriorated with increasing AC content. In addition, the pore size and structures of the supporting layer became large due to the partial agglomeration of the AC in the CA. The relationship between adsorption time and adsorption capability was investigated. It was found that the 15% AC composite membrane possessed the highest adsorption efficiency for acid blue dye. The adsorption equilibrium was 58.69 mg/g for 60 mg/L acid blue dye at 120 min. For acid yellow and acid dark dye, the adsorption equilibria were 58.23 and 58.34 mg/g, respectively.

    更新日期:2019-11-26
  • Concentration Effects in Frozen Polyacrylonitrile Solutions During the Gelation Process as Studied by Viscoelastic Techniques
    J. Macromol. Sci. B. Phys. (IF 1.204) Pub Date : 2019-09-29
    Yutaka Tanaka, Daisuke Takenaka, Keigo Samoto

    Dynamic viscoelasticity measurements were carried out for N, N-dimethylacetamide solutions of polyacrylonitrile (PAN) frozen at −40 °C to characterize the effect of concentration in the frozen state in relation to the freezing and thawing method of the PAN gel. The storage (G′) and loss moduli (G″) were measured for samples obtained by separating the frozen and unfrozen regions during the thawing step. The G′ were also acquired for solutions without the separation (referred to as post-thawing solution), written as G′fro G′unfro and G′post−thaw for frozen region, unfrozen region, and post-thawing solution, respectively. The relationship, G′unfro < G′post−thaw < G′fro was observed, showing that regions of higher and lower concentrations were developed in the thawing step. ( G′fro/ G′post−thaw) was considered a relative index of the concentration increase, to be compared for those of the initial and later stages within the thawing step. ( G′fro/ G′post−thaw) was much greater than 1 in the initial stage, and then decreased and approached 1 in the later stage. The behavior of ( G′fro/ G′post−thaw) was discussed with reference to the effects of freezing time and concentration on the gelation time. The microscopic separation between the dilute and concentrated phases induced at the freezing step was proposed as the physical process to interpret the viscoelastic data.

    更新日期:2019-11-26
  • Rheological Behaviors and Properties of Poly (Ether Ether Ketone) In-Situ Blends: Effect of Chemical Structure of Added Thermotropic Liquid Crystalline Polyarylates
    J. Macromol. Sci. B. Phys. (IF 1.204) Pub Date : 2019-10-21
    Gong Chen, Peng Chen, Luxian Zeng, Jianjun Xu, Pengqing Liu

    Two kinds of thermotropic liquid crystalline polyesters (TLCP) with different chemical structures were used as flow modifiers during the melt spinning of poly (ether ether ketone). One of TLCPs, named PAT-S, was a kind of aromatic polyester synthesized from 4-acetoxybenzoicacid and 6-hydroxy-naphthoic acid, and the other one named, PEEKAR, was a block copolymer based on poly (ether ether ketene) (PEEK) oligomers and PAT-S oligomers. The effects of the chemical structures of the prepared TLCPs on the rheological behavior of the TLCP/PEEK blends were measured by rheological measurements, and then the structure and properties of the TLCP/PEEK in-situ blend fibers were studied by a series of methods, including differential scanning calorimetry (DSC), wide angle X-ray diffraction (WRXD), optical microscopy (OM), scanning electron microscopy (SEM), orientation degree tests, mechanical properties tests, etc. The results showed that the melt viscosity of PEEK could be effectively reduced by nearly 20% by adding a small amount of PEEKAR or PAT-S with the viscosity reducing effect of PEEKAR on PEEK being greater than that of PAT-S; this was mainly caused by the better compatibility between PEEK and PEEKAR because of the similar segment structures. The crystallinity of the PEEK fibers increased by nearly 50% with addition of both TLCPs, indicating that both the PEEKAR and PAT-S could serve as nucleating agent as well. The results from the morphology analysis clearly proved that PEEKAR had a better compatibility with the PEEK resin compared with PAT-S. The tensile strength of the PEEK fibers could be improved to some extent by adding PEEKAR, while it was obviously reduced after adding PAT-S.

    更新日期:2019-11-26
  • Fatigue Life Prediction of a Rubber Mount Based on the Continuum Damage Mechanics
    J. Macromol. Sci. B. Phys. (IF 1.204) Pub Date : 2019-10-23
    Qian Li, Zhi-Wei Wen, Gang He, Ming-Hai Yuan, Wei-Dong Zhu

    Failure analysis and fatigue life prediction are important steps in the design procedure of industrial products to assure the safety and reliability of their components. A new methodology to predict the fatigue life of a rubber mount based on the continuum damage mechanics is proposed in this study. The hyperelastic constitutive model of the natural rubber material in the mount was fitted using the three parameter Mooney-Rivlin model. A damage variable was introduced and the evolution function of cumulative damage in the rubber material was derived. The parameters in the damage function were acquired based on uniaxial tensile tests and fatigue life tests of the natural rubber specimens. Then the finite element analysis (FEA) models of the rubber mount for loads in the X and Y directions were established and the strain contours and the maximum principal strains of the rubber mount under various loads were calculated. The maximum principal strain was used as the fatigue parameter, which was substituted into the natural rubber’s fatigue life damage function to predict the fatigue life of the rubber mount. Finally, the fatigue lives of the rubber mount under various loads were measured on a fatigue test rig to validate the accuracy of the fatigue life prediction method. The test results indicated that the fatigue lives predicted agreed fairly well with the test results and the fatigue prediction method should be applicable to both rubber and other types of components.

    更新日期:2019-11-26
  • The Crystalline Structure of Nascent Ultra High Molecular Weight Single Particles and Its Change on Heating, as Revealed by in-situ Synchrotron Studies
    J. Macromol. Sci. B. Phys. (IF 1.204) Pub Date : 2019-08-27
    Liubov Myasnikova, Marina Baidakova, Valerii Drobot’ko, Sergei Ivanchev, Elena Ivan’kova, Elena Radovanova, Maria Yagovkina, Vyacheslav Marikhin, Yan Zubavichus, Pavel Dorovatovskii

    A solvent-free route to high performance ultra-high molecular weight polyethylene (UHMWPE) film threads is currently under intensive development. It involves compaction/sintering of UHMWPE reactor powder at T < Tm followed by orientation hardening of the sintered film cut into narrow strips. However, not any kind of reactor powder can be transformed into the desired high-performance material. The presence of a monoclinic crystalline phase (MP) in the powder is considered as one of the key parameters indicating its applicability for solvent-free processing. Since the MP is stable only under stress, the assumption has been made that the observed MP is generated during tableting for X-ray analyses rather than during synthesis of the nascent powder. We show that comparative X-ray analysis of a tablet and a single “virgin” particle using synchrotron radiation indicates that the MP content in the virgin particle was far less than that in the compressed tablet. Only the (001) MP peak was resolved while the others were severely overlapped with the normal, orthorhombic reflections. Thus, it supports our idea that the widely observed MP phase is, for the most part, generated during the sample preparation for the X-ray analyses.

    更新日期:2019-11-19
  • Optical and Conductivity Studies of Cr3+ Doped Polyvinyl Pyrrolidone Polymer Electrolytes
    J. Macromol. Sci. B. Phys. (IF 1.204) Pub Date : 2019-08-28
    K. Sreekanth, T. Siddaiah, N. O. Gopal, N. Krishna Jyothi, K. Vijaya Kumar, Ch. Ramu

    Polymer electrolyte films of polyvinyl pyrrolidone (PVP) embedded with various concentrations of Cr3+ ions were prepared by a solution casting technique. The complexation between the Cr3+ ions and the polymer was confirmed by Fourier transform infrared (FTIR) spectroscopy and UV–vis spectroscopy. The electrical conductivity of the films was measured using an impedence analyzer in the frequency range of 42 Hz to 5 MHz at ambient temperature. It was observed that the conductivity increased with the increase in the Cr3+ ion concentration. UV–visible absorption spectra in the wavelength range of 200–800 nm were used to determine the direct and indirect optical energy band gaps and optical absorption edge. Both of the optical band gaps decreased with the increase in Cr3+ ion concentration. FTIR studies on pure and Cr3+ doped PVP polymer films revealed the vibrational changes that occurred due to the effect of the dopant Cr3+ ions in the polymer. Our results suggested that Cr3+, as a dopant, is a good choice to improve the electrical properties of PVP polymer electrolytes.

    更新日期:2019-11-19
  • Structure and Properties of Poly(Oxypropylene) Diamine Intercalated Montmorillonite/Epoxy Composites
    J. Macromol. Sci. B. Phys. (IF 1.204) Pub Date : 2019-10-11
    Lu Li, Yi Zhang, Xia Liao, Zengheng Hao, Xingyue Sheng, Pan Liu

    A type of micro-multilayer particles with a structure similar to that of nacre was prepared by poly(oxypropylene) diamine (POPD) intercalating organic montmorillonite (OMMT). The prepared particles were then blended with epoxy resin (EP) to obtain high performance EP composites. The Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis and contact angle analysis of the OMMT showed that the (POPD) had been successfully intercalated into the OMMT and the micro-multilayer particles were obtained as expected. Transmission electron microscope observation of the cured composites further confirmed that the micro-multilayer particles were well maintained in the EP network. The tensile and bending strength and glass transition temperature of the OMMT/EP composites were all increased compared with those of the EP. All these showed that the addition of the OMMT was an effective way to obtain high performance EP composites.

    更新日期:2019-11-19
  • Mathematical Modeling of Drug Release in a Phase-Transient Temperature-Responsive Drug Delivery System in Spherical Coordinates
    J. Macromol. Sci. B. Phys. (IF 1.204) Pub Date : 2019-10-01
    Mohammad Sirousazar

    A sphere-shaped drug delivery system responsive to temperature, as a unique external stimulus, was introduced and its performance mathematically studied at the pseudo-steady state. The system is composed of three individual sections, including the drug core, phase-transient intermediate shell, and protective polymeric shell. An ON-OFF release of drug could be achieved by increasing or decreasing the environmental temperature around the melting point of the intermediate shell and the smartness of system is due to the solid-liquid phase transition of this shell. The ON-OFF response of the system was mathematically modeled by solving the governing heat and mass transfer equations at the pseudo-steady state. The results showed the lag time of the system in the ON state, the cumulative released drug in the ON state and the fractional undesired release of drug in the OFF state are strongly under the influences of different kinds of factors, including the geometrical characteristics of the system (e.g., the radius of the drug core and the thicknesses of the intermediate and polymeric shells), the physical properties of the system (e.g., the thermal conductivities and diffusion coefficients of the intermediate and polymeric shells), and the environmental and operation conditions.

    更新日期:2019-11-19
  • Surface Modification of Poly (ether ether ketone) with a Medlite C6 (ND-YAG Q-Switched) Skin Treatment Laser
    J. Macromol. Sci. B. Phys. (IF 1.204) Pub Date : 2019-08-20
    Maryam Mehdizadeh Omrani, Afra Hadjizadeh

    Poly ether ether ketone (PEEK), a synthetic polymer, is expected to be useful as a biomaterial due to its appropriate mechanical, chemical, and biocompatibility properties. However, this polymer is biologically inert, requiring surface modification to improve its adhesion to bone cells for use as a bone substrate. Surface properties, such as roughness and hydrophilicity, are important factors in the adhesion of biomaterials to the surrounding tissue; therefore, in this study, laser treatment was performed for surface modification. The aim of the research described here was to investigate the effect of two laser parameters, fluency and wavelength, on the surface roughness and hydrophilicity to determine the optimum parameters for improving surface adhesion. The surface topography and average roughness (Ra) were investigated by atomic force microscopy (AFM). Surface morphology was also observed with an optical microscope, and the hydrophilicity of the surfaces was investigated with static contact angle tests. The results obtained showed that the samples treated at the wavelength of 532 nm with fluency of 8 J/cm2, compared to fluencies of 4 and 12 J/cm2, showed improved surface properties. However, in terms of radiation wavelength, the wavelength of 1064 nm at these three fluencies showed the most promising results for enhancing the surface properties of PEEK for bone implant applications.

    更新日期:2019-11-15
  • Synthesis of a Cationic Polymer-Bentonite Composite Utilizing a Simple and Green Process for the Adsorption of Acid Orange 7 from Aqueous Solution
    J. Macromol. Sci. B. Phys. (IF 1.204) Pub Date : 2019-07-27
    Luyan Wang, Fanqiu Meng, Meishan Pei, Wenjuan Guo, Guoran Liu, Sen Du

    A one-step, green process is reported for synthesis of poly([2-(methacryloyloxy)ethyl] trimethylammonium chloride) (PMETAC) modified bentonite (Bent-PMETAC). The Bent-PMETAC was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Zeta potential, scanning electron microscopy (SEM) and thermal gravimetric analysis (TGA). The results indicated that large amounts of PMETAC were successfully grafted on the surface and interlayers of bentonite, and changed the Zeta potential of the sample from negative to positive. Acid Orange 7 (AO 7), as adsorbate, was used to test the anionic dye adsorption of the samples. The batch adsorption results implied that this novel Bent-PMETAC adsorbent exhibited a much higher removal (95%) of AO 7 than bentonite (10%). In addition, the adsorption process was hardly influenced by pH, which is in good agreement with the results of the Zeta potential analysis. The equilibrium adsorption isotherms and the adsorption kinetics of AO 7 fitted well to the Langmuir model and pseudo-second-order kinetic model, respectively. The maximum adsorption capacity of AO 7 onto Bent-PMETAC was 208.6 mg·g−1 at 298 K, which is much higher than for most other materials. Overall, the results indicated the Bent-PMETAC is a low-cost, simple synthesis and highly efficient adsorbent for anionic dye removal from aqueous solutions.

    更新日期:2019-11-15
  • Influence of Prestrain on the Mechanical Properties and Constitutive Model of Hydroxyl-Terminated Polybutadiene Films as Used for Coatings in Solid Rocket Motors
    J. Macromol. Sci. B. Phys. (IF 1.204) Pub Date : 2019-08-05
    Yongqiang Du, Jian Zheng, Wei Wang, Jianzhuang Zhi, Xiao Zhang

    Low-field 1H NMR tests and uniaxial tensile tests of hydroxyl-terminated polybutadiene (HTPB) films, subjected to a prestrain before the NMR and tensile tests related to the use of the HTPB as coatings for solid rocket motors, were carried out. The mechanisms of the variations of crosslinking density, tensile strength and maximum elongation of the HTPB films with prestrain were analyzed, and a Gaussian function model of the variation of the crosslinking density with prestrain was obtained. By introducing crosslinking density and prestrain as correction coefficients, two prestrain constitutive models of the stress-strain relationship of HTPB films related to the Mooney-Rivlin and Ogden hyperelastic constitutive models, respectively, were established and the parameters of the models were obtained based on nonlinear least squares fitting. The accuracy and effectiveness of the prestrain constitutive models were determined with that based on the Ogden model proven to be of important engineering value.

    更新日期:2019-11-15
  • High-Speed Melt Spinning of Polylactide/Poly(Butyleneterephthalate) Bicomponent Fibers: Mechanism of Fiber Structure Development and Dyeing Behavior
    J. Macromol. Sci. B. Phys. (IF 1.204) Pub Date : 2019-08-29
    Yutaka Kawahara, Motohiro Hanada, Shota Onosato, Wataru Takarada, Midori Takasaki, Koji Takeda, Yoshimitsu Ikeda, Takeshi Kikutani

    Bicomponent fibers consisting of polylactide (PLA) as the sheath and poly(butylene terephthalate) (PBT) as the core were produced by high-speed spinning to obtain materials suitable for medical clothing. The higher-order structure of the PLA fiber component appeared to exhibit simple, alternately stacked, uniaxially oriented amorphous and crystalline regions. Therefore, fairly large tanδ peaks were observed for single-component PLA fibers, even when the orientation-induced crystallization was achieved by high-speed spinning. By conjugating PLA with PBT, although limited mutual interference with the crystallization of each component occurred, both the PLA (Mw = 170,000, L-lactide content = 98.7%) and PBT (intrinsic viscosity = 0.835-0.865 dL/g) could crystallize on a high-speed spinning line, and the proposed formation of a shish-kebab-like structure in the PBT component enhanced the thermal stability of the bicomponent fibers, particularly resulting in shrink-proof properties. The bicomponent fibers developed herein could be deeply dyed at 98 °C, with results comparable to those of industrial polyester, and peeling of the PLA skin layer was rarely observed, even when the dyed fibers were flattened by a rubbing force.

    更新日期:2019-11-15
  • Fabrication of Polypropylene (PP)/Poly Trimethylene Terephthalate (PTT)/Nanoclay Nanocomposite Fibers with Tailored Properties
    J. Macromol. Sci. B. Phys. (IF 1.204) Pub Date : 2019-08-16
    Mohammad Reza Habibolah Zargar, Ahmad Mousavi Shoushtari

    The main aim of this study was to deal with one of the major drawbacks of polypropylene (PP) fibers, i.e., low resiliency and low dyeability, by incorporating polytrimethylene terephthalate (PTT) fibrils, as a dispersed material, and organoclay, as a nano-filler, into the PP polymer matrix. The presence of 10 wt% of PTT and 0.5–1 wt% organoclay in the PP nanocomposite fibers led to an approximately 18.5% and 45.5% increase in the resilience behavior and dye uptake, respectively, compared to pure PP fibers, without using highly toxic carriers. The lowest mean diameter of the nano-fibrils was 75 nm for the hot drawn nanocomposite fiber samples as measured by scanning electron microscopy (SEM). The results of DSC indicated that the presence of both PTT and organoclay significantly influenced the crystallinity of the PP which also confirmed their nucleating effects in the nanocomposite fiber.

    更新日期:2019-11-13
  • Poly (Vinyl Alcohol)/Chitosan/Akermanite Nanofibrous Scaffolds Prepared by Electrospinning
    J. Macromol. Sci. B. Phys. (IF 1.204) Pub Date : 2019-08-20
    Mohammad Reza Bafandeh, Hamid Mir Mojarrabian, Ali Doostmohammadi

    Electrospinning, as an effective method for preparation of scaffolds for cell growth templates, has attracted great attention. In this study electrospinning was used to prepare poly (vinyl alcohol) (PVA)/chitosan scaffolds for bone tissue engineering. In order to improve the bioactivity and mechanical properties of the fibrous scaffolds, 0.5, 1 and 2 wt% akermanite, a calcium silicate based bioceramic, was added to the electrospinning solution. The morphology of the electrospun scaffolds was observed by using field emission-scanning electron microscopy and their mechanical strengths were analyzed by tension tests. The results showed that the formed scaffolds consisted of fibers with less than 100 nm diameter. In the case of the composite containing 1 wt% akermanite, the fibers were more homogeneous and no beads were formed during electrospinning, while in the composite containing 2 wt% akermanite a considerable number of beads were formed which we attribute to an improper viscosity of the electrospinning solution. Among the different compositions, the composite containing 1 wt% akermanite showed higher ultimate tensile strength (10.6 MPa) and fracture strain (9%). These values were increased by crosslinking the scaffold by reaction with glutaraldehyde, up to 13 MPa and 9.4%, respectively.

    更新日期:2019-11-13
  • Assessment of the Microstructure and Mechanical Properties of Polycarbonate (PC)/Acrylonitrile Butadiene Rubber (NBR) Blends Reinforced with Multi-wall Carbon Nanotubes
    J. Macromol. Sci. B. Phys. (IF 1.204) Pub Date : 2019-08-20
    Nafiseh Nikfar, Hossein Izadi-Vasafi, Leyla Goudarzi

    A series of polycarbonate (PC)/acrilonitrile butadiene rubber (NBR)/multi-wall carbon nanotube (MWCNT) nanocomposites were prepared via melt compounding in an internal mixer. The effect of the MWCNT content on the morphology and the thermal and mechanical properties of the prepared nanocomposites were studied. The morphologies of the samples were investigated by field-emission scanning electron microscopy (FESEM) and the thermal properties by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The tensile mechanical results of the nanocomposites showed a decrease in elongation at break with an increase of only 2 wt% of MWCNT content in the PC/NBR blends, and an increasing value in elastic modulus and tensile strength of the nanocomposites. The FESEM images showed that the MWCNTs had good affinity with the polymers and no compatibilizer was needed for making the nanocomposites. The DSC and TGA results showed an increase in thermal stability with addition of MWCNTs because of the more thermally stable carbon nanotubes particles which was uniformly dispersed within the nanocomposites.

    更新日期:2019-11-13
  • Synthesis and Characterization of a Novel Self-colored Fluorescent Polycarbonate Urethane based on the 1,8-Naphthalimide Group
    J. Macromol. Sci. B. Phys. (IF 1.204) Pub Date : 2019-08-20
    Ehsan Zamani, Hossein Yahyaei, Alireza Khosravi, Mohsen Mohseni, Hanieh Shaki

    The synthesis of a novel self-colored polyurethane (PU) is described using 4-amino-N-propanoic acid-1,8-naphthalimide dye. To synthesize the self- colored PU, the dye was added to the PU prepolymer at the chain extension step. PU and self-colored PU were characterized by using Fourier transform infrared spectroscopy (FTIR), UV-visible spectroscopy and Fluorometry. The thermal behavior of the PU and self-colored PU were investigated by differential scanning calorimetry (DSC). The spectra indicated that the addition of dye to the polymer chain did not affect the glass transition temperature (Tg = -39 °C). Tensile strengths and Young’s modulus of the samples were assessed using a tensile strength test; they revealed that addition of the dye to the polymer structure enhanced the Young’s modulus and increased the mechanical strength of the PU. X-ray diffraction (XRD) was used for evaluation of the crystal phase of the polymer; it revealed that both components were amorphous.

    更新日期:2019-11-13
  • Correction
    J. Macromol. Sci. B. Phys. (IF 1.204) Pub Date : 2019-11-01

    (2019). Correction. Journal of Macromolecular Science, Part B: Vol. 58, No. 8, pp. 722-722.

    更新日期:2019-11-01
  • Thermal Stability and Decomposition Kinetics of Poly(Methacryloyloxyethyl Trimethyl Ammonium Chloride-Co-Acrylamide)
    J. Macromol. Sci. B. Phys. (IF 1.204) Pub Date : 2019-07-08
    Xingqin Fu, Tingting Chen, Xiao Xu, Yuejun Zhang

    Poly(methacryloyloxyethyl trimethyl ammonium chloride-co-acrylamide) (P(DMC-AM)), is widely used for various applications under a wide range of conditions. In this work the thermal stabilities and decomposition kinetics of P(DMC-AM) with various intrinsic viscosities, synthesized in our laboratory, were studied by thermogravimetric analysis (TGA) at various heating rates, 5, 10, 20 and 40 K/min, and differential scanning calorimetry (DSC) at 10 K/min, all under a dynamic nitrogen atmosphere. The kinetic parameters were calculated using a model fitting method (Coats–Redfern, CR) and two model–free methods (Kissinger–Akahira–Sunose, KAS and Flynn–Wall-Ozawa, FWO). The result showed that all samples exhibited three steps of mass loss, one for the elimination of the adsorbed water and organic solvents and two for the thermal decomposition of P(DMC-AM). The first decomposition stage for the three samples was in the range of 5% to 45%, the second decomposition stage in the range of 65% to 95% and with 55% conversion separating the first and second decomposition stages. The E values increased with the increasing intrinsic viscosity of the samples. Hence, P(DMC-AM) had good thermal stability and the higher the molecular weight, the better the thermal stability was.

    更新日期:2019-10-25
  • Evaluation of Properties and Structural Transitions of Poly-L-lysine: Effects of pH and Temperature
    J. Macromol. Sci. B. Phys. (IF 1.204) Pub Date : 2019-07-08
    Imen Naassaoui, Adel Aschi

    The structural response to temperature and pH changes of poly-l-lysine (PLL) has been studied by a variety of experimental methods including turbidimetry, dynamic light scattering, and Zeta potential analysis. The experimental results and the molecular dynamics simulations showed that the PLL structural transitions were a result of a competition between electrostatic repulsion, which promotes an extended state, and the hydrophobic effect, which favors a compact state. In fact, as the pH was decreased, the PLL conformation changed from α-helix to the random coil and the hydrophilic volume increases resulted in a transition to spherical micelles which then swelled due to charge-charge repulsions. Following a rise in temperature and/or at high pH, PLL undergoes the α-helix-to-β-sheet transition and reacted more rapidly to form hydrophobic aggregates.

    更新日期:2019-10-25
  • The Effect of Some Physical Factors on the II → I Phase Transition of Isotactic Polybutene-1
    J. Macromol. Sci. B. Phys. (IF 1.204) Pub Date : 2019-08-19
    M. Kaszonyiová, F. Rybnikář

    Isotactic polybutene-1 exhibits excellent physical, mechanical and chemical properties dependent on its most important polymorphic crystal forms, called forms I, II and III. The most stable form, form I, is generated via a slow, solid-state transformation of the tetragonal, kinetically favored form II. The slow transformation rate of form II to I, accompanied by sample shrinkage, attains its maximum at ca 25 °C and takes 7–10 days, which is a technical problem for iPB-1 practical applications. We describe here the results reported in the literature by the authors and others of the effect of various physical factors that affect the transformation rate, with the goal of determining means of accelerating it; it is noted explanations of the effects are limited and in many cases, not given.

    更新日期:2019-10-25
Contents have been reproduced by permission of the publishers.
导出
全部期刊列表>>
2020新春特辑
限时免费阅读临床医学内容
ACS材料视界
科学报告最新纳米科学与技术研究
清华大学化学系段昊泓
自然科研论文编辑服务
中国科学院大学楚甲祥
上海纽约大学William Glover
中国科学院化学研究所
课题组网站
X-MOL
北京大学分子工程苏南研究院
华东师范大学分子机器及功能材料
中山大学化学工程与技术学院
试剂库存
天合科研
down
wechat
bug