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Paper is a widely used packaging material and is nowadays regaining importance, e.g., as bio-based and biodegradable material. Moreover, new technologies such as polymer-fiber composites, printed electronics and the deep drawing of paper are developing. The process stability and also the resulting quality of paper converting processes such as coating, metallization, printing, and the printing of electronics are highly affected by the hygroexpansion of paper. In order to reduce production instability and to choose and develop paper substrates with ideal characteristics, critical parameters need to be known. This paper offers an extensive overview of those parameters, starting at a molecular and microscopic level with the effect of the constituents and morphology of single fibers, before moving on to paper contents, chemical modifications and additives and finally concluding with paper production and fiber network modification. It was found that the major influences are single fiber sorption, inter-fiber contacts, microfibril angle, fiber morphology (length, width, curliness) and fiber orientation. This review gives new ideas and insights for technologists working in research, development and production optimization of paper-based products. [ABSTRACT FROM AUTHOR]

The article presents a list of papers related to materials science published in volumes 39, 40 and 41 of the periodical. The articles include "Adhesively-Bonded Joints and Repairs in Metallic Alloys, Polymers and Composite Materials," by A. Baldan, "Thermo-Mechanical Fatigue of Shape Memory Alloys," by E. Hornbogen and "Models in Thermoluminescence," by C. Furetta and G. Kitis.

The Journal of Materials Science is known for publishing papers on polymer materials. The journal has several editors who specialize in polymers, including Chris Cornelius, Steve Eichhorn, Jamie C. Grunlan, Dale Huber, Maude Jimenez, Greg Rutledge, Jean-François Gohy, and Mohammad Naraghi. These editors handle papers on a wide range of topics related to polymers, including composites, materials for the life sciences, coatings, electronic materials, chemical routes to materials, and ceramics. Each editor has their own area of expertise and has made significant contributions to the field. The journal is a valuable resource for researchers interested in polymeric materials and related topics. [Extracted from the article]

The article presents a list of several articles on chemistry including "Adhesively-bonded joints and repairs in metallic alloys, polymers and composite materials," by A. Baldan, "Thermo-mechanical fatigue of shape memory alloys," by E. Hornbogen, and "Observations of common microstructural issues associated with dynamic deformation phenomena: Twins, microbands, grain size effects, shear bands, and dynamic recrystallization," by L. E. Murr and E. V. Esquivel.

The article presents a list of articles related to materials science published in volumes 39, 40, and 41. The articles include "Adhesively-bonded joints and repairs in metallic alloys, polymers and composite materials," "Observations of common microstructural issues associated with dynamic deformation phenomena: Twins, microbands, grain size effects, shear bands, and dynamic recrystal," and "Role of entropy of fusion in phase transformation and selfdiffusion."

The article presents a list of review articles published in the previous issues of the journal including "Adhesively-Bonded Joints and Repairs in Metallic Alloys, Polymers and Composite Materials," "Thermo-Mechanical Fatigue of Shape Memory Alloys," "Role of Entropy of Fusion in Phase Transformation and Self-Diffusion," "Models in Thermoluminescence," and "Electrical Applications of Carbon Materials."

The article presents a list of articles published in the "Journal of Materials Science," including "Adhesively-Bonded Joints and Repairs in Metallic Alloys, Polymers and Composite Materials," "Thermo-Mechanical Fatigue of Shape Memory Alloys," "Role of Entropy of Fusion in Phase Transformation and Self-Diffusion," "Synthetic Routes, Properties and Future Applications of Polymer-Layered Silicate Nanocomposites," and "Models in Thermoluminescence."

This article presents a list of several research papers published in the "Journal of Materials Science." Some of the papers are "Adhesively-Bonded Joints and Repairs in Metallic Alloys, Polymers and Composite Materials," "Observations of Common Microstructural Issues Associated With Dynamic Deformation Phenomena: Twins, Microbands, Grain Size Effects, Shear Bands, and Dynamic Recrystallization," and "Use of Polymers for Cement-Based Structural Materials."

This article focuses on papers published in the "Journal of Material Science," vol. 39 and 40. Some of the papers are: Adhesively-bonded joints and repairs in metallic alloys, polymers and composite materials by A. Baldan; Thermo-mechanical fatigue of shape memory alloys by E. Hornbogen; Role of entropy of fusion in phase transformation and self-diffusion by G.P. Tiwari, J.M. Juneja and Y. Iijima; Electrical applications of carbon materials by D.D.L. Chung; Nano and macro-structured component fabrication by electron beam-physical vapor deposition by J. Singh and D.E. Wolfe.

This article presents a list of research papers related to materials science, published in the "Journal of Materials Science." These research papers include "Adhesively-Bonded Joints and Repairs in Metallic Alloys, Polymers and Composite Materials," by A. Baldan; "Thermo-Mechanical Fatigue of Shape Memory Alloys," by E. Hornbogen; "Role of Entropy of Fusion in Phase Transformation and Self-Diffusion," by G.P. Tiwari, J.M. Juneja and Y. Iijima; "Models in Thermoluminescence," by C. Furetta and G. Kitis; and "Electrical Applications of Carbon Materials," by D.D.L. Chung.

The article presents a list of review papers published in the volumes 39 and 40 of the "Journal of Materials Science." Some of the papers published in the volume 39 are--'Adhesively-bonded joints and repairs in metallic alloys, polymers and composite materials,' by A. Baldan, 'Thermo-mechanical fatigue of shape memory alloys,' by E. Hornbogen, 'Electrical applications of carbon materials,' by D.D.L. Chung. Some of the papers published in the volume 40 of the 2005 issue of the journal are--'Nano and macro-structured component fabrication by electron beam-physical vapor deposition,' by J. Singh and D. E. Wolfe.

The article presents several review papers published in the Volumes 39 and 40 of the "Journal of Materials Science" including "Adhesively-Bonded Joints and Repairs in Metallic Alloys, Polymers and Composite Materials," by A. Baldan, "Thermo-Mechanical Fatigue of Shape Memory Alloys," by E. Hornbogen, "Recent Developments in Polyurethane-based Conducting Composites," by J. Njuguna and K. Pielichowski, "A Review of Anode Materials Development in Solid Oxide Fuel Cells," by San Ping Jiang, Siew Hwa Chan, and "Advances in the Study on Wear of Metals by Polymers," by Si-Wei Zhang and Ren-Yang He.

Presents review papers in the volumes 39 and 40 of the February 15, 2005 issue of the "Journal of Materials Science". Adhesively-bonded joints and repairs in metallic alloys, polymers and composite materials; Thermo-mechanical fatigue of shape memory alloys; Electrical applications of carbon materials,

Presents reviews papers submitted to the "Journal of Materials Science," Volumes 37 and 38. "Structure and properties of glass-like carbon," BY L.A. Pesin; "Improving cement-based materials by using silica fume," by D.D.L.Chung; "Electron backscatter Kikuchi diffraction in the scanning electron microscope for crystallographic analysis," by K.Z. Baba-Kishi; "Progress in Ostwald ripening theories and their applications to nickel-base superalloys," by A. Baldan; "Progress in Ostwald ripening theories and their applications to the precipitates in nickel-base superalloys," by A. Baldan; "Processes and influencing parameters of the solid particle erosion of polymers and their composites," by N.-M. Barkoula and J. Akrger-Kocsis.

Polymeric thickeners play a vital role in controlling water retention in paper coating processes. In this work, the interactions between various polymer water retention agents (i.e., thickeners) and coating pigments were investigated, in an attempt to improve the understanding of the thickening mechanisms. Adsorption isotherms of the polymeric thickeners, up to four types of commercial thickeners based mainly on copolymers of acrylate and acrylic acid, onto mineral pigments (clay pigment and ground calcium carbonate, GCC) were determined. It was found that the adsorption behaviour was strongly affected by the surface structure of the pigment. All the selected thickeners showed greater affinity towards clay pigment than calcium carbonate. The influence of the selected thickeners on coating mixtures behaviour at tow shear rate was also investigated. In coating mixture based on clay, it was found that HASE (hydrophobically modified alkali swellable emulsion) thickener that has the highest adsorption led to more effective thickening. All the selected thickeners showed moderate effect on the viscosity of the coating mixture based on GCC. The presence of thickeners also produced the coated paper with smooth and homogeneous surfaces, revealed by SEM observation. [ABSTRACT FROM AUTHOR]

With the aim to understand the effect of thermal condition on phase separation in polymer-modified bitumen (PMB), this paper numerically investigates four PMB binders under five thermal conditions between 140 and 180 °C. Based on a phase-field model previously developed by the authors for PMB phase separation, the updated model presented in this paper uses temperature-dependent parameters in order to approach the concerned temperature range, including mobility coefficients, interaction and dilution parameters. The model is implemented in a finite element software package and calibrated with the experimental observations of the four PMBs. The experimental results are well reproduced by the model, and it is thus believed that the calibrated parameters can represent the four PMBs. The simulation results indicate that the model proposed in this paper is capable of capturing the stability differences among the four PMBs and their distinct microstructures at different temperatures. Due to the transition of some PMBs from the thermodynamically stable state at 180 °C to the unstable state at 140 °C, a homogenization process may occur during the cooling applied numerically. After the transition, the PMBs start to separate into two phases and gradually form the binary structures controlled by the temperature. It is indicated that the cooling rate slightly affects the final pattern of the PMB binary microstructure, although the process can be more complicated in reality due to the potential dynamic reasons. [ABSTRACT FROM AUTHOR]

Four kinds of conjugated microporous polymers (CMPs) with imine structures were synthesized by a Sonogashira coupling reaction followed by a postreaction between aldehydes and amines. Palladium nanoparticles (Pd NPs) were successfully supported on the CMPs to prepare Pd/CMP heterogeneous catalysts and were used to catalyze the Suzuki–Miyaura coupling reaction. The number of aromatic nuclei and nitrogen atoms in the CMPs highly affects Pd loading. In the Suzuki–Miyaura coupling reaction, the Pd/CMP with good Pd NPs dispersibility and appropriate Pd content (Pd/CMP-NA) exhibited the highest catalytic efficiency with 100% conversion and 95.4% yield which can be used for many substrates. The Pd/CMP-NA heterogeneous catalyst was easy to recover and still exhibited good catalytic efficiency after 5 cycles. To further understand the catalytic mechanism of Pd/CMP-NA on the Suzuki–Miyaura coupling reaction, we proposed a rational catalytic cycle. This paper provides an idea for the structural design of CMPs used for Suzuki–Miyaura catalytic reaction. [ABSTRACT FROM AUTHOR]

Coordination bonding of Ni(II) tetraazamacrocyclic (TAMC) complexes to carboxylic groups of organic polymers and graphene oxide paper (GOP) is proposed for a facile generation of paramagnetic centers by combining two diamagnetic components. The coordination functionalization occurs under basic conditions in water solution at room temperature. The coordination configuration of central Ni(II) changes from tetracoordinated square-planar to hexacoordinated pseudooctahedral, which implies the conversion from low-spin to high-spin nickel centers. In the case of organic polymers, the coordination bonding of Ni(II) macrocycles gives rise to characteristic changes in coloration (from yellow-orange to violet-blue), as well as clearly manifests itself in UV–visible, FTIR and EPR spectra. In the case of GOP, in addition to evident changes in FTIR spectra, morphological alterations in the mat surface and an increase in the mat thickness are observed in SEM images, which can be explained by an intercalating effect of voluminous macrocyclic cations, as well as by partial disintegration of GOP structure due to the liquid-phase treatment. The effective magnetic moments of tetraazamacrocycles attached to organic polymers vary from 0.88 to 1.47 BM, whereas for GOP considerably higher values of 2.10 and 2.87 BM were obtained. [ABSTRACT FROM AUTHOR]

Spherulite is the main microstructure feature of semicrystalline polymers, exhibiting a non-axisymmetric geometry with a sheaf structure in the center. In the initial stage of growth, spherulite is manifested initiation from the sheaf structure with a certain orientation. The size and orientation of sheaf structure are affected by various processing parameters. Previous research considered spherulite as completely radially symmetric structures, ignoring the effects of anisotropic sheaf on mechanical properties. In this paper, an anisotropic micromechanical model for evaluating the mechanical properties of semicrystalline polymers was proposed. The microstructure of single spherulite was modeled with different sheaf sizes, orientations, and crystallinities. The viscoplastic constitutive model together with the Arruda–Boyce model was used to describe the micromechanical behaviors of the crystalline lamellae and amorphous lamellae, respectively. The evolution of inhomogeneous plastic deformation, interlayer deformation and slip activities in spherulite was observed under tension. The results shown in this work enhance the understanding of the microstructure–property relationship of semicrystalline polymers, which, in turn, guides the development of advanced manufacturing techniques for tailoring mechanical properties. [ABSTRACT FROM AUTHOR]

Highlights the Third International Conference Polymer Fiber 2004 in Manchester, England. Theme of the event; Keynote speakers; Programs and activities.

Recently, functional applications of thermoplastic foams have received extensive attention from the research and materials communities, focusing on their various applications, key challenges, material systems designs, processing methods, and cellular structure characteristics needed for specific functional applications. This review paper starts with consideration of the microcellular foaming mechanism and basic concepts of microcellular foam processing, followed by polymer modification methods, and crucial factors that determine the performance of thermoplastic foams. Special emphasis has been placed on the synergies between foaming and reinforcements, including functional fillers and polymer blends; improvements in homogeneous, functional properties by achieving uniform cell structure and cell dispersion in polymer systems; and comparison of melt processing and solvent-based methods. Then, a wide array of advanced functional applications for foams—such as lightweight applications, heat and sound insulation, electromagnetic shielding, tissue engineering, oil spill cleanup, shape memory, and flexible materials—will be presented. In particular, the relationships between cellular structure and anticipated properties—including mechanical, barrier, dielectric, biomedical, and other properties required in advanced functional applications—will be discussed. Finally, we will outline a future perspective of lightweight and functional foams and suggest recommended future work regarding functional microcellular foams. [ABSTRACT FROM AUTHOR]

This paper focuses on determining the criteria for defect formation during the early stages of thermal binder removal within an ethylene vinyl acetate (EVA) polymer filled with submicron SiC ceramic powder. The only product of the early stage thermal degradation reaction of EVA within an inert atmosphere is acetic acid. This single component and well characterized organic reaction product has allowed the defect forming criteria to be definitively examined. It will be shown that bloating occurs in the early stages of binder removal as a result of pressure build-up in the specimen resulting from acetic acid formed from the thermal elimination reaction of EVA. The first part of this paper examines defect formation occurring in the pure polymer within a hot-stage optical microscope. Bubble formation is observed in the pure polymer. Next, bloating occurring in the molded system is examined. The affect of mineral oil on bloating is also discussed as well as the effect that molding pressure has on bloating. It was found that molding pressure effects defect formation. Finally, this paper presents binder removal maps that were developed for specimens up to 8 mm thick. These bloating maps indicate the existence of two primary bloating regimes. [ABSTRACT FROM AUTHOR]

This paper presents the first-principles investigation on interfacial adhesive strength between grafted polymer and cellulose. Focusing on maleic anhydride-grafted polypropylene, which is expected to be used in various applications including automobiles, a simple interfacial model was constructed under a local tensile loading condition. Then the stress–strain relation, deformation of molecular structure and breaking process were discussed. From comparison of mechanical responses among three chemically possible bonding configurations, it was clarified that the monoester bond exhibited higher interfacial strength than the diester bond. We also found that controlling the bonding configuration can improve the interface strength by about 50% compared to when primary OH groups react to form ester bonds. It was proved that this first-principles calculation model was effective for the definitive design and development of chemical modification of nanocellulose. [ABSTRACT FROM AUTHOR]

Luffa spp. is readily available and widely grown in Asia and Africa and is a rich source of natural fibres for composite development. This paper reviews research findings on Luffa fibres and their composites. The progress of research, novel findings that affect the paradigm of the research area, recent trends, knowledge gaps and future perspectives are evaluated. It was found that the average chemical composition of Luffa fibres ranges from 57–74% cellulose, 14–30% of hemicellulose, 1–22% of lignin and 0–12.8% of the other components. Luffa fibres were usually extracted by drying. Furthermore, the most common modification technique was found to be by alkali mercerisation. About 53% of the research studies made use of epoxy resins for their base polymer making it the most popular polymer type for Luffa fibre reinforced composites. The composites are fabricated usually by manual mixing and hand layup and the most common curing technique was found to be compression moulding (about 63% of the research studies). The mechanical, thermal, crystalline and other properties of the composites are also considered in this review. Further interesting areas suggested for future work include investigation of the effect of drying, more trials with L. acutangula and utilisation of multi-resin ternary systems. It is concluded that Luffa is a promising material for composite development and based on its favourable properties is likely to continue playing an important role for the years to come. [ABSTRACT FROM AUTHOR]

Additive manufacturing (AM) is a broad definition of various techniques to produce layer-by-layer objects made of different materials. In this paper, a comprehensive review of laser-based technologies for polymers, including powder bed fusion processes [e.g. selective laser sintering (SLS)] and vat photopolymerisation [e.g. stereolithography (SLA)], is presented, where both the techniques employ a laser source to either melt or cure a raw polymeric material. The aim of the review is twofold: (1) to present the principal theoretical models adopted in the literature to simulate the complex physical phenomena involved in the transformation of the raw material into AM objects and (2) to discuss the influence of process parameters on the physical final properties of the printed objects and in turn on their mechanical performance. The models being presented simulate: the thermal problem along with the thermally activated bonding through sintering of the polymeric powder in SLS; the binding induced by the curing mechanisms of light-induced polymerisation of the liquid material in SLA. Key physical variables in AM objects, such as porosity and degree of cure in SLS and SLA respectively, are discussed in relation to the manufacturing process parameters, as well as to the mechanical resistance and deformability of the objects themselves. [ABSTRACT FROM AUTHOR]

This paper aims to study the coalescence phenomenon of two different polymers PVDF and PMMA. The paper is divided in two parts: the first part is devoted to the experimental work, and the second one focuses on the modeling of the coalescence phenomenon. The first step was a physicochemical and rheological characterization. Then, the coalescence tests have been performed on droplets derived from PVDF and PMMA polymers using a polarized light optical microscope combined with a hot stage. The effect of several significant parameters like temperature and particle size was investigated. The second part of this study is focused on the modeling of the coalescence phenomenon based on the well-known Bellehumeur model. The latter has been commonly used to describe the coalescence phenomenon between identical grains. The novelty of the present work consists in the extension of the coalescence model to wider describe the coalescence phenomenon between grains of different polymers. In addition, probabilistic analysis was performed in order to investigate the effect of the parameters governing the coalescence model, namely the viscosity, the surface tension and the relaxation time. The results have shown a good compromise between the experimental results and the predictive generalized Bellehumeur model. [ABSTRACT FROM AUTHOR]

Polymers, such as PVDF and PMMA, have been commonly adopted as host materials for gel polymer electrolytes (GPEs), leading to excessive consumption of fossil fuel as well as severe white pollution. Nanocellulose (NC) is a kind of renewable and biodegradable carbohydrate polymer so that its possible application in gel polymer electrolyte for lithium-ion battery is discussed in this paper. The NC membrane with a porous network is prepared by freeze-drying method. To further extend its application into GPE, glutaraldehyde (GA) is used as cross-link agent to enhance the performance of the membrane. Cross-linked by 6 wt% GA, the skeleton membrane exhibits satisfactory mechanical property and thermal stability. The GPE gives moderate electrochemical performance and reverse capability. The experimental results show that the introduction of nanocellulose provides a direction for the development of carbohydrate polymer applied in GPE. [ABSTRACT FROM AUTHOR]

The subject matter discussed herein relates generally to fabrics composed of micro-denier fibers wherein said fibers are fractured/fibrillated by mechanical means by employing ‘Islands-in-the-Sea’ (I/S) technology instead of the conventional splittable fibers such as segmented pie. More particularly, the present subject matter relates to methods for manufacturing high strength, high surface area, flexible, and durable fabrics through the use of bicomponent fibers fractured mechanically by hydroentangling where the hydroentangling energy is sufficient for separating the fibrils as well as entangling (bonding) the fibers. This paper specifically deals with physical properties of spunbond fabrics consisting of I/S bicomponent fibers. This paper also deals with the bonding energy requirements for fracturing I/S filament. The results for two different polymer combinations (Polyester/Nylon and Nylon/Polyethylene) are discussed below. The influence of different process parameters and fiber characteristics on the physical properties of the fabrics is discussed. The role of the number of islands in the cross-section is also discussed. Finally, the influence of changing the ‘Sea’ polymer on the fabric performance is also discussed. [ABSTRACT FROM AUTHOR]

The present paper regards the development of polyurea/polyurethane (PUa/PU) and PUa/PU–silica hybrid shell microcapsules (MCs), loaded with Ongronat®2500, a commercial type of oligomeric methylene diphenyl diisocyanate with increased functionality, as core material. Ongronat® 2500 has a wide range of applications either for the production of rigid polyurethane foams and as cross-linking or self-healing agent. The MCs were achieved by a facile, one-pot process, consisting of an oil-in-water microemulsion system combined with interfacial polymerization processing, employing a higher reactivity isocyanate, toluene diisocyanate, to competitively contribute to the shell formation. Ethylenediamine, polyethylenimine (PEI), triethoxy(octyl)silane (n-OTES) and 3-(2-aminoethylamino) propyltrimethoxysilane (aminosilane) were tested as active, or "latent" active hydrogen (H) sources, and their effect on the MCs morphology, encapsulation yield, shelf life, shell's chemical structure and thermal stability was assessed. The MCs are aimed at the development of a new generation of adhesive formulations, which are mono-component, self-reactive, eco-friendly and with low health hazards, for industries such as the footwear, construction, aerospace and automotive. MCs' characterization was performed using Fourier transformed infrared spectroscopy, thermogravimetric analysis and scanning electron microscopy. It was possible to obtain MCs with a high loading of Ongronat®2500, exhibiting a core–shell morphology, an increased shell resistance to temperature and improved shelf life. The combination of PEI and n-OTES led to the best compromise between encapsulation yield and shelf life. Finally, a confinement effect of the encapsulated macromolecules is herein shown for the first time, by the drastic narrowing of the NCO peak at the FTIR spectrum of the MCs. [ABSTRACT FROM AUTHOR]

Shear thickening solution is rarely encountered but the solution with low concentration and high salinity is really desired in enhanced oil recovery. In this paper, we developed a comb micro-block hydrophobic association polymer (CBHAP). The polymer solution with high salinity showed an obvious shear thickening behavior, even if the polymer concentration was very low (1 g/L). In addition, with the increase in salinity (> 20 g/L) and temperature, shear thickening phenomenon will be more obvious. We analyzed that the unique rheological behavior was influenced by the comb micro-blocked structure and the forces transition from intramolecular to intermolecular when the curled polymer chains were stretched under shearing. In porous media, high permeability and low flow rate were beneficial to achieve the shear thickening flow. The unique property will endow CBHAP better mobility control ability than conventional polymers, especially in high permeability reservoirs or fractured reservoirs. [ABSTRACT FROM AUTHOR]

Single-material flexible actuators that can produce non-uniform deformation in response to external stimuli have attracted considerable interests due to their facile fabrication process and excellent actuation behavior. However, the recognition of actuation state with easily perceived and detectable signal is still a challenge. In this paper, we report an actuator behavior of single-material inverse opal photonic crystal films, which are in response to a variety of solvents based on swelling/de-swelling process. The actuator exhibits improved responsiveness due to the enhanced mass transport of solvent molecules in periodic inverse opal with macroporous structure. Especially, peaks in reflective spectra and corresponding structure colors are obviously changed, providing a simple and effective optical technology for optical recognition of micro-locomotion. Based on the above characteristics, we demonstrate the potential applications of this photonic crystal actuator as solvent-driven gripper, walking device and rolling motor, showing great promise in advanced soft robot for many important intelligent areas. [ABSTRACT FROM AUTHOR]

On the basis of the reports from 2010 to 2018, the chemical structure, production methods and applications of polyurethane ionomers were reviewed. The paper presents ionogenic reagents and counterions responsible for the incorporation of anionic and cationic groups into polyurethane chains and the resulting physicochemical properties of these polymers. The most important applications of synthesized ionomers as a waterborne polyurethane, elastomer materials, biomaterials and materials for special applications (electronics, nanocomposites) were presented. [ABSTRACT FROM AUTHOR]

Heat treatment technology is usually used for the processing of metal materials. In this paper, polymer carbon nitride (g-C3N4) is secondarily calcined at 590 °C. A series of nitrogen-doped g-C3N4 are obtained by adjusting the holding time. The doping of nitrogen atoms changes the electronic structure of the catalyst and narrows the band gap. In addition, the escape of ammonia during the secondary calcinations leads to the increase in the specific surface area of the catalyst, which is helpful to enhance the photosensitization effect. Among them, the sample obtained by holding time at 2 h has the highest photogenerated carrier separation efficiency, the largest specific surface area and the best photocatalytic degradation of methylene blue. [ABSTRACT FROM AUTHOR]

Hydrogels are polymeric networks with tridimensional structure, which are able to load water and other substances. Such property makes hydrogels suitable for innumerous applications in biomedical field. Hydrogels are being used as raw materials in pharmaceutical formulations for more than 60 years, while significant progress is very well documented in topical use. Natural and synthetic polymers have been applied to develop smart hydrogels that respond to physiological stimuli to follow the release of the loaded bioactive ingredient. This paper discusses the most relevant polymers commonly used in pharmaceutical formulations for modified topical delivery. [ABSTRACT FROM AUTHOR]

Ionic polymer transducers (IPT) consist of an ion-exchange membrane plated with flexible conductive electrodes on their outer surface. Compared to other types of electromechanical transducers, ionomeric transducers have the advantage of high-strain output (>9%), low-voltage operation (<5 V), and high sensitivity in the charge-sensing mode. A novel fabrication technique for ionic polymer transducers named the Direct Assembly Process (DAP) was developed in this paper. The DAP allows the use of any type of ionomer, diluent, and conducting powder in the transducer, and permits the exploration of any novel ionomeric design. In this paper the effect of diluent content of the IPT, electrode thickness, and composition were optimized in term of maximum peak strain and strain rate generated by an IPT. Decreasing viscosity and increasing polarity and content of the diluent were demonstrated to increase the strain rate of an IPT. The thickness of the electrode was varied and correlated with the maximum strain generated due to a 2 V step input. This study also demonstrated that RuO2 composition has an optimal loading of 42 vol%, while SWNT electrodes have an optimal performance at around 30 vol%. [ABSTRACT FROM AUTHOR]

Poly(L-lactide) (PLLA) porous materials have become increasingly important for practical applications. However, the methods for preparing PLLA-based porous particles are quite limited. The chirality of PLLA materials remains scarcely explored even though PLLA is a well-known chiral polymer. In this paper, we establish an unprecedented, facile approach for preparing PLLA particles with lamellar structures by precipitation polymerization. By adjusting polymerization conditions (solvent and temperature), a series of PLLA particles with tunable morphology was fabricated. The resulting particles were characterized by SEM, CD, XRD, DSC, and GPC measurements. We further explored chiral resolution ability of the PLLA particles used as chiral additive to induce enantioselective crystallization. According to SEM, CD, and XRD characterizations, PLLA particles show considerable enantioselectivity and preferentially induce L-threonine to crystallize from the racemic solution. Besides, enhancing the crystallinity of PLLA particles is beneficial for improving the particles’ enantiodifferentiating ability. The present study provides a versatile platform for developing novel PLLA materials, which deserve more attention as chiral biomaterials. [ABSTRACT FROM AUTHOR]

The tension-tension fatigue behavior and damage mechanism of basalt fiber-reinforced epoxy polymer (BFRP) composites at different stress ratios are studied in this paper. The fatigue experiments were performed under stress ratios, R = σmin/σmax of 0.1 and 0.5, while the lifetime and the stiffness degradation were monitored and analyzed to investigate the effect of stress ratios. The damage propagation during fatigue loading was periodically monitored by using an in situ scanning electron microscope (SEM). The results show that the fatigue life decreases and the fatigue life degradation rate increases with the decrease of stress ratio for examined BFRP composites. The stiffness degradation is also sensitive to different stress ratios, showing a greater stiffness loss before failure at lower stress ratio. From the SEM images, it is indicated that the micro-damage mode shifts from interface debonding and matrix cracking into fiber breaking with decreasing stress ratios. [ABSTRACT FROM AUTHOR]

As medical materials, silicone polymers are poor in mechanical properties and in resistance to fouling for its non-specific adsorption of proteins, cells, etc. This paper introduces a new type of silicone-silicone interpenetrating polymer network (IPN) composing of two curing reactions: One was radical coupled reaction, and the other was ring opening of epoxy by amino groups. The IPN were characterized by Fourier transform IR spectroscopy (FT-IR), dynamic mechanical analysis, cross section scanning electron microscope, and mechanical property. IPN structure could be formed in a co-continuous phase, while the sea-island phase could be also found up to amino content, and then tear strength and elongation at break were obviously increased. ATR FT-IR, X-ray photoelectron spectroscopy, and static water contact angles confirmed that IPN surfaces showed the hydrophilicity dependent on surface amino-epoxy component. The static water contact angles were greatly decreased to the lowest 69.3°. Both qualitative and quantitative bovine serum albumin (BSA) adsorption assay confirmed that, compared with pure polydimethylsiloxane, BSA adsorption on IPN substrates were greatly decreased, with the most 85%. [ABSTRACT FROM AUTHOR]

Focuses on the Manchester conference regarding polymer fibers from July 10-12, 2002 in England. Keynote speakers; Activities and programs; Topics discussed in the conference.

In this paper, bamboo-like, O-doped carbon tubes with hierarchical pore structure have been fabricated by the direct pyrolysis of dual cross-linked polydivinylbenzene (PDVB) tubes. The bamboo-like, cross-linked PDVB tubes are firstly synthesized by cationic polymerization of divinylbenzene in cyclohexane using BF/EtO complex as the initiator. After a secondary cross-linking being imposed by Friedel-Crafts reaction in CCl using anhydrous AlCl as the catalyst, the obtained dual cross-linked, carboxylic acid functionalized PDVB tubes are directly subjected to pyrolysis, yielding bamboo-like, O-doped porous carbons. The resultant O-doped porous carbon tubes (BCTF-900, pyrolyzed at 900 °C) exhibit a trimodal pore structure (micro-, meso-, and macropores) with a relatively high specific surface area of 595 m g and a low total pore volume of 0.37 cm g. Such bamboo-like carbon tubes display good volumetric capacitive performance (254 F cm at 0.5 A g), moderate volumetric energy density (12.9 Wh L at 428 W L), and excellent cycling stability (the capacitance retention has remained at 96.9% after 10000 cycles at 2 A g). Due to their unique bamboo-like architecture and trimodal pore structure, the PDVB-derived carbon tubes should have widely application prospect. [ABSTRACT FROM AUTHOR]

Biodegradable or transient electronics is an emerging technology whose key characteristic is an ability to dissolve, resorb, physically disappear or disintegrate in physiological environments after fulfilling their functions over prescribed time frames. Biodegradable electronics as temporary implants can be safely absorbed by the body, and as green electronics can effectively alleviate landfill and environmental issues caused by electronic wastes, which are expected to ultimately eliminate associated costs and risks resulting from recycling operations. In this review, the state of the art of the biodegradable polymers, their fabrication techniques, and potential applications in environment friendly electronic skins (e-skins) are comprehensively summarized and systematically discussed. In addition, the future outlook for the development of biodegradable e-skins is also discussed at the end. It is expected that this review will potentially provide vital tools and beneficial strategies for the design of biodegradable e-skins with the functions of diagnosis, therapy and green sensing that are beneficial for human healthcare and environmental protection. [ABSTRACT FROM AUTHOR]

This paper reports an efficient solution dip coating method for the fabrication of highly transparent and conductive single-walled carbon nanotubes (SWCNTs) based thin films. The key to achieve this is properly preparing the polymer surfaces. In this paper we report a surface pretreatment approach of combining air plasma treatment and silane water solution rinsing for polyethylene terephthalate substrate. After this surface pretreatment, one dip (using a home-made dip coater) of SWCNT solution can yield a thin film of the sheet resistance less than 100 ohms/square (Ω/□) and transparency around 90% at the wavelength of 550 nm; while two dips can produce a thin film of the sheet resistance less than 80 Ω/□ and transparency around 80% at the wavelength of 550 nm. The carbon nanotube thin film performances achieved are close to those of the ITO coatings reported in the literature and the process developed is suitable for both mass production and lab sample preparations. [ABSTRACT FROM AUTHOR]

This paper presents the results obtained for the effects of the loading rate and of the testing temperature on the mechanical properties, particularly on the stiffness and on the ultimate tensile strength, of a geopolymer reinforced with glass or carbon fibres. HIGH-SILICA geopolymer powder from CLUZ- CYECH and two reinforcement fibres (glass fibres—type AR and carbon fibre - HTS 5631) were used. The displacement rate is varied from 0.02 until to 2 mm/s and the testing temperature is increased from the room temperature until the temperature of 300 °C. For the case of geopolymers reinforced with carbon fibres and glass fibres, the increase of the displacement rate from 0.002 to 2 mm/s led to an improvement on the ultimate flexure strength of about 33 and 31%, respectively. The same dependency was observed for the stiffness, with variations of loading rate of 39 and 53%, for carbon fibres and glass fibres, respectively. Increasing the room temperature until the temperature of 300 °C decreases significantly both the ultimate strength and the flexure stiffness for both reinforcements. However, a major drop on both the stiffness and the strength occurred up to 150 °C. [ABSTRACT FROM AUTHOR]

Natural fibre-reinforced plastics (NFRP) with renewable polymers as matrices are expected to be an increasing market in the future. In this context the quantification of natural fibre volume content in composites is an important parameter for manufacturers to check the laminate quality. This paper reports a new time and cost efficient method for the determination of natural fibre volume content with a good reproducibility. The measurement of the natural fibre volume content is attributed to the quantification of the total carbon content of the composite as sum parameter determined by chemical ultimate analysis never used for fibre-reinforced plastics before. The differentiation of resin matrix and natural fibre is possible by accounting the different carbon fractions of both components. The fibre weight content can be determined from the detected total carbon of the test samples after the measurement of a calibration line from mix standards. Based on the known densities of the natural fibre and of the resin matrix, the fibre weight content is converted into the corresponding volume content. The fibre volume content of porous and also compact composite parts can be calculated by this approach. The fibre volume content can be measured by this method with a standard deviation of ±1%. [ABSTRACT FROM AUTHOR]

The objectives of this paper are to present the results of experimental study and analysis on the behaviour and the strength of reinforced geopolymer concrete slender columns. The experimental work involved testing of twelve columns under axial load and uniaxial bending in single curvature mode. The compressive strength of concrete for the first group of six columns was about 40 MPa, whereas concrete with a compressive strength of about 60 MPa was used in the other six columns. The other variables of the test program were longitudinal reinforcement ratio and load eccentricity. The test results gathered included the load carrying capacity, the load-deflection characteristics, and the failure modes of the columns. The analytical work involved the calculation of ultimate strength of test columns using the methods currently available in the literature. A simplified stability analysis is used to calculate the strength of columns. In addition, the design provisions contained in the Australian Standard AS3600 and the American Concrete Institute Building Code ACI318-02 are used to calculate the strength of geopolymer concrete columns. This paper demonstrates that the design provisions contained in the current standards and codes can be used to design reinforced fly ash-based geopolymer concrete columns. [ABSTRACT FROM AUTHOR]

Even though the ultimate mechanical properties of degraded polymers are widely reported in the literature, few papers dealt with the elastic properties of polymers after submitted to a degradation source. This topic is important to the understanding of the effects of degradation in polymer chemical and physical structure and also in the design of products where load bearing capability is a relevant requirement. The aim of this paper was to investigate and effects of photodegradation on the Young modulus of polypropylene. Several exposure conditions were applied in order to get a wide picture of this effect and hence to propose a reasonable mechanism for this influence. The elastic characteristics were discussed based on the variations in carbonyl index and in crystallinity during exposure and a new elastic property, named global compliance, was proposed. This article also analyses the influence of ultraviolet source on the photodegradation behaviour. [ABSTRACT FROM AUTHOR]

In the present paper, the following topics are reviewed in detail: (a) the available adhesives, as well as their recent advances, (b) thermodynamic factors affecting the surface pretreatments including adhesion theories, wettability, surface energy, (c) bonding mechanisms in the adhesive joints, (d) surface pretreatment methods for the adhesively bonded joints, and as well as their recent advances, and (e) combined effects of surface pretreatments and environmental conditions on the joint durability and performance. Surface pretreatment is, perhaps, the most important process step governing the quality of an adhesively bonded joint. An adhesive is defined as a polymeric substance with viscoelastic behavior, capable of holding adherends together by surface attachment to produce a joint with a high shear strength. Adhesive bonding is the most suitable method of joining both for metallic and non-metallic structures where strength, stiffness and fatigue life must be maximized at a minimum weight. Polymeric adhesives may be used to join a large variety of materials combinations including metal-metal, metal-plastic, metal-composite, composite-composite, plastic-plastic, metal-ceramic systems. Wetting and adhesion are also studied in some detail in the present paper since the successful surface pretreatments of the adherends for the short- and long-term durability and performance of the adhesive joints mostly depend on these factors. Wetting of the adherends by the adhesive is critical to the formation of secondary bonds in the adsorption theory. It has been theoretically verified that for complete wetting (i.e., for a contact angle θ equal to zero), the surface energy of the adhesive must be lower than the surface energy of the adherend. Therefore, the primary objective of a surface pretreatment is to increase the surface energy of the adherend as much as possible. The influence of surface pretreatment and aging conditions on the short- and long-term strength of adhesive bonds should be taken into account for durability design. Some form of substrate pretreatment is always necessary to achieve a satisfactory level of long-term bond strength. In order to improve the performance of adhesive bonds, the adherends surfaces (i.e., metallic or non-metallic) are generally pretretead using the (a) physical, (b) mechanical, (c) chemical, (d) photochemical, (e) thermal, or (e) plasma method. Almost all pretreatment methods do bring some degree of change in surface roughness but mechanical surface pretreatment such as grit-blasting is usually considered as one of the most effective methods to control the desired level of surface roughness and joint strength. Moreover, the overall effect of mechanical surface treatment is not limited to the removal of contamination or to an increase in surface area. This also relates to changes in the surface chemistry of adherends and to inherent drawbacks of surface roughness, such as void formations and reduced wetting. Suitable surface pretreatment increases the bond strength by altering the substrate surface in a number of ways including (a) increasing surface tension by producing a surface free from contaminants (i.e., surface contamination may cause insufficient wetting by the adhesive in the liquid state for the creating of a durable bond) or removal of the weak cohesion layer or of the pollution present at the surface, (b) increasing surface roughness on changing surface chemistry and producing of a macro/microscopically rough surface, (c) production of a fresh stable oxide layer, and (d) introducing suitable chemical composition of the oxide, and (e) introduction of new or an increased number of chemical functions. All these parameters can contribute to an improvement of the wettability and/or of the adhesive properties of the surface. [ABSTRACT FROM AUTHOR]

This paper reviews stress development mechanisms and stress measurement techniques for polymer coatings. Most polymeric coatings shrink during and after solidification due to chemical reaction, solvent evaporation, phase separation, or some combination thereof. Coating adhesion, however, prevents shrinkage from occurring freely; this frustration of in-plane shrinkage leads to a tensile stress in the plane of the coating. At the same time, stress accumulates, it may be relaxed by processes such as molecular motion. The measured stress at any time is the result of the competition between stress buildup from frustrated shrinkage and stress relief from relaxation. Accumulation of stress is a problem because it can lead to defects such as cracks. An understanding of stress development in various types of polymeric coating systems will lead to strategies for material selection, process optimization, and defect elimination. In this paper, background on stress development is provided, followed by an overview of stress measurement methods for polymer coatings. The remainder of the paper focuses on stress development during the drying and curing of polymer coatings, drawing many examples from previous stress measurement studies. [ABSTRACT FROM AUTHOR]

Recent experiments with hexagonal boron nitride ( h-BN) have shown the successful covalent and non-covalent functionalization of these boron nitride nanostructures, especially nanosheets (BNNS). This paper explores the synthesis of several thiophene-based polymers with conjugated pendant groups and their reactions with BNNSs. Specifically, two phenyl carboxylic acid functionalized polythiophene polymers, poly[3-(4-methoxycarbonylphenyl)thiophene] and poly[3-(4-benzoic acid)thiophene], have been prepared and reacted with exfoliated BNNSs. The resulting complexes between the conjugated polythiophene polymers and the BNNS are reported and characterized by their reaggregation stability and by spectroscopic methods. [ABSTRACT FROM AUTHOR]

In the field of cultural objects conservation efficient stabilisation of fragile and failing, multilayered decorative coatings is a complex and challenging task. This paper introduces a new application of the standardised double-cantilever beam (DCB) test method to improve the understanding of the mechanical properties of failing material and to determine the effect of polymeric agents (consolidants) added for their stabilisation. The adapted DCB method was used to measure the fracture energy, G, and the fracture behaviour of brittle, protein-bound (gesso-type) foundation layers on wooden substrates that typically suffer from delamination and flaking. Wooden DCB specimens containing a brittle layer of protein glue mixed with finely ground clay powder were prepared, fractured, then consolidated with a range of commonly used polymer formulations and finally re-fractured to provide measurements for direct comparison. Consolidants tested included gelatine-based glues (bovine hide glue, isinglass; both pre-stained with Fast Green dye), acrylics (Lascaux Medium for Consolidation, Paraloid B-72/B-48N), poly(vinyl acetates) (Mowilith 50, Mowilith DMC2) and poly(vinyl alcohol) (Mowiol 3-83). Before second-phase fracture cross-sections were taken from the DCB specimens for determining penetration depth and gap-filling ability. For better visibility, the specimens containing acrylics were stained with Solvent blue G dye; iodine-potassium iodide was used for staining the other synthetic consolidants. The resulting data showed that the test method could determine measurable differences between initial G (47 ± 22 J/m) and post-consolidation G values. Also, penetration behaviour could be well characterised and valuable, and detailed information on the type and location of crack path propagation was gained. [ABSTRACT FROM AUTHOR]