Abstract: Abstract A simple method to covalently crosslink chitosan using poly(ethylene glycol) diacid as crosslinking agent is proposed. Networks net-chitosan-ι- PEG(COOH)2 were obtained by heating chitosan in aqueous PEG600(COOH)2 solutions at a temperature higher than 60°C. IR spectroscopy revealed the formation of amide bonds. It is shown that the obtained chemical networks are pH-sensitive hydrogels with enhanced hydrophilicity. The equilibrium degree of swelling of the hydrogels is determined by the conditions of their preparation - heating temperature and mole ratio between chitosan and the crosslinker. The ability of the polymer networks to facilitate bone regeneration processes was shown by in vivo implantation experiments.

Abstract: Abstract The water stability of electrospun poly(vinyl alcohol) (PVA) nanofibres was improved significantly by annealing with poly(acrylic acid) (PAA). Effects of annealing were tested on solution-cast PVA/PAA films by measurement of the swelling degree. The influence of PVA/PAA ratio, annealing temperature and period, molecular weight of PAA, and addition of esterification catalyst was investigated. The results were verified by a significant improvement of the water-stability of electrospun PVA/PAA composite nanofibres.

Abstract: We have formulated a quantitative definition of wear different from the current imprecise definitions. Wear is defined as the unwanted loss of solid material from solid surfaces due to mechanical interaction. The debris method currently used to quantify wear produces results strongly dependent on conditions. We have performed multiple scratch tests for a variety of polymer samples: poly- propylene, polytetrafluoroethylene and a polyester. In each of the materials studied, the scratch penetration depths reach a constant value at a given force after 8 scratches or so. Similarly, the scratch recovery (final, healing) depths for a fixed force reach a plateau after a dozen or so scratch tests. Thus, strain hardening by repetitive scratching takes place. A likely explanation is formation of a more ordered phase - as seen before in mechanical tests by Siegmann, Aharoni, Faitelson et al. Given these results we define a measure of wear W(F) for a given indenter geometry and force F as W(F) = limn→∞ Rh(F) where n is the number of tests performed and Rh is the final (residual, healing) depth after viscoelastic recovery. The present results confirm also our earlier ones that scratch recovery is another useful way to characterize viscoelasticity.

Abstract: Various crosslinking agents have been used to frontally cure the unsatu- rated polyester derived by the reaction of maleic anhydride and 1,2-propanediol. The effect of composition of the curing mixture on the front velocity and its maximum temperature, as well as on the thermal properties of the obtained materials, is described.

Abstract: Abstract Small-strain equilibrium modulus data of polydimethylsiloxane (PDMS) networks are reviewed. 58 different articles in the literature with values of the modulus of end-linked PDMS networks were found [1-58] including more than 250 values of the small-strain equilibrium modulus as function of variables in the crosslinking system. The dominating variable is shown to be the molecular weight of PDMS as expected, whereas the functionality of the crosslinker methylhydrosiloxane/ dimethylsiloxane copolymer is shown to be less important in good agreement with the phantom model. The data collected was fitted to the phenomenological model of Langley and Graessley including an entanglement contribution. The fitted entanglement plateau (0.16 MPa) is in good agreement with literature values and with the theoretical prediction of the tube model. Experimental data for the Mooney-Rivlin constants was found and it was shown that C2 is constant with increasing functionality. Furthermore it was found that trapped entanglements can be split into two categories, viz. locked entanglements contributing to the C1 term and traditionally trapped entanglements contributing to C2.

Abstract: Direct methanol fuel cells (DMFCs) using a proton exchange membrane as electrolyte is an attractive option for electricity generation. The most widely used membrane in the DMFC system is based on a perfluorinated polymer bearing sulfonic acid functions like Nafion ® . The latter combines chemical, mechanical and thermal stability and high protonic conductivity but shows elevated methanol permeability. We propose the preparation of a novel type of hybrid membranes to tentatively solve this problem. This innovative material results from the homo- geneous dispersion of a nano-scaled inorganic filler within Nafion. The filler consists of stacks of negatively charged alumino-silicate layers (Cloisite), with a positive counter-ion in the interlamellar space. The purpose of the addition of this filler is to decrease methanol diffusion through the polymer membrane without decreasing too much the ionic conductivity.

Abstract: The average molecular weight and molecular weight distribution of polyhydroxybutyrate can be affected by different bacterial strains, different cultivation time and also different carbon sources. Food waste was proven to have a high potential in the induction of biosynthesis of polyhydroxybutyrate with different production yields and physical properties. A specific culture of Alcaligenes latus DSM 1124 and Staphylococcus epidermidis, which was isolated from sesame oil, were selected to ferment several types of food wastes as nutrients, including malt waste, soy waste, confectionery waste, milk waste, vinegar waste and sesame oil, into polyhydroxybutyrate in this study. Average molecular weight and molecular weight distribution of polyhydroxybutyrate were measured by gel permeation chromatography. By comparing the results with those obtained using sucrose as a carbon source, the average molecular weight of polyhydroxybutyrate produced from food wastes was increased for Alcaligenes latus; however, it was decreased for S. epidermidis. Thermal analyses of the biopolymer produced by S. epidermidis indicated that the melting point of the polymer produced from sesame oil as carbon source was 188°C, the highest temperature among those polymers produced by using ice cream, malt, and soya wastes.

Abstract: Flow-induced crystallisation in the course of melt spinning changes properties of as-spun fibres and modifies dynamics of the process. Velocity, stress and temperature profiles depend on the speed of on-line crystallisation. Very important but little studied is coupling between crystallinity and rheological properties of the polymer melt. Effects of crystallisation on the dynamics of melt spinning and on the rheological behaviour have been discussed and compared with model calculations and available experimental data.

Abstract: Several methods allowing the removal of copper-based ATRP active complexes from crude amino-functionalized polymethacrylate chains are com- pared. Among them, precipitation in basic medium is one of the most efficient techniques since it allows high recovery yields (above 90%) with a residual metal content as low as 5 ppm. Extraction methods such as liquid-liquid phase sepa- ration and dialysis but also selective adsorption on acidic macroporous ion exchange resin constitute other attractive alternatives. As far as water-insoluble polymers are concerned, catalyst adsorption on alumina remains the most uni- versal method and provides acceptable recovery efficiency. However, we want to stress the key-importance of the experimental adsorption conditions and above all the relative content of alumina used for catalyst extraction.

Abstract: Abstract In this work we have investigated the effects of CaCO3 nanofiller pretreatment on the properties of polyurethane (PU) composites prepared by a mixing procedure. The aim was to enhance interactions at the matrix/filler interface and to improve the distribution of the filler in the polyurethane matrix. CaCO3 nanofiller was treated with two different functional trialkoxysilanes, viz. γ-aminopropyltriethoxysilane (AMPTES) and γ-glycidoxypropyltrimethoxysilane (GPTMS). Fourier transform IR spectroscopy of the pre-treated CaCO3 surface indicates that AMPTES formed a high-molecular-weight ladder-type structure on the CaCO3 surface, while GPTMS was adsorbed in the form of a lower-molecular-weight oligomeric structure. Increased ultimate tensile strength and elongation were obtained for PU + CaCO3 nanocomposites with silane pre-treated filler. This can be explained as the consequence of better stress transfer through the composite, observed on scanning electron micrographs, due to an improved adhesion between PU matrix and silane-treated fillers. The reinforcement effect is more pronounced for PU composites with aminosilane-treated CaCO3 filler in comparison to filler treated with glycidoxysilane.

Abstract: Adherent thin polymer films have been prepared by sequential electrodeposition of ethyl acrylate (EA) and acrylonitrile (AN) onto nickel. Their composition has been studied by IR spectroscopy and time of flight-secondary ion mass spectrometry. Morphology and thickness have been analyzed by atomic force microscopy and ellipsometry, respectively, and compared to single component films of PEA and PAN. No microphase separation was detected in the mixed PEA/PAN films. These show a granular morphology comparable to that of PAN films. The grains contain the two constitutive polymers, as confirmed by the selective thermal degradation of PEA.

Abstract: Reversible addition fragmentation chain transfer (RAFT) polymerizations of styrene in fluid CO2 have been carried out at 80°C and 300 bar using cumyl dithiobenzoate as the controlling agent in the concentration range of 3.5·10 -3 to 2.1·10 -2 mol/L. This is the first report on RAFT polymerization in fluid CO2. The polymerization rates were retarded depending on the employed RAFT agent concentration with no significant difference between the RAFT polymerization performed in fluid CO2 and in toluene. Full chain length distributions were analyzed with respect to peak molecular weights, indicating the successful control of radical polymerization in fluid CO2. A characterization of the peak widths may suggest a minor influence of fluid CO2 on the addition reaction of macroradicals on the dithio- benzoate group.

Abstract: Abstract Linear polyamides with high aliphatic content were prepared through step-heating melt polycondensation of tridecanedioic acid with various diamines. The synthesized polyamides were characterized comprehensively by means of IR, NMR and Raman spectroscopy. In addition, thermogravimetry, differential scanning calorimetry and dynamic mechanical analysis were used to investigate thermal properties of the obtained polyamides. It was found that melting and crystallization temperatures decrease as the aliphatic content increases. X-ray diffraction was applied to determine the crystal structures of the polyamides.

Abstract: Thermoplastic polyurethane (TPU) is an important class of elastomers that has found many novel and specialized applications where high mechanical and chemical performances are prerequisites. They are known for their good mechanical strengths, wear and tear resistance, and low-temperature elasticity. The aim of this work is the study of the viscoelastic behavior of thermoplastic polyurethane (TPU), polypropylene (PP) and their blends using a dynamic mechanical analysis (DMA). Dynamic mechanical analysis is sensitive technique for characterization the structure and viscoelastic behavior of polymeric materials. Blends of TPU+PP, TPU and PP in their pure form were prepared using a laboratory twin-screw extruder (Haake Record 90). The primary and secondary viscoelastic functions were determined. Primary viscoelastic functions, storage modulus (E’ ), loss modulus (E’ ’ ) and loss tangent (tand) were evaluated in the temperature range – 100oC to 250oC. The secondary viscoelastic functions creep, recovery and creep modulus were investigated in creep-fatigue regime at temperatures 25, 35, 45, 55 and 65oC. A master curve for the reference temperature 25oC for the creep modulus of TPU, PP and TPU+PP blends are created by applying the time-temperature correspondence principle. In the literature, there are no creep data of TPU/PP blends. However, because from both a scientific and a commercial point of view is desirable to investigate the stability of the blends on the creep influence. On the base of the results obtained the correlation, continuous phase and phase morphology of investigated systems was discussed

Abstract: Abstract Using amylopectin (AP) and a derivative, we systematically investigated their turbulent drag reduction characteristics and shear stability. The expected shear stability of polysaccharides as drag reducing and flocculating agents triggered our study on structural modification of AP. For this purpose, we prepared a derivative of AP, viz. AP grafted with polyacrylamide (GA), in which the granular form of AP powder (≈10 μm) changed into a mixture of larger fibrils and lumps. Using a rotating-disk apparatus, we measured the shaft torque and calculated the turbulent drag reduction (DR) efficiency under various experimental conditions, i.e., different polymer concentration, rotation speed, and temperature. Contrary to AP, GA showed relatively high DR efficiencies (27%) and very strong shear resistance.

Abstract: A robust and reproducible method for the molar mass analysis of neutral and anionic copolymers based on methacrylic acid and different (meth)acrylates has been developed. Size exclusion chromatography (SEC) using a novel poly- ester-based packing as the stationary phase and dimethylacetamide (DMAC) as the mobile phase yields highly accurate results for copolymers with a methacrylic acid content up to 50 wt.-%. To suppress the different polar and ionic interactions between the sample molecules, the stationary phase and the eluent, DMAC was modified with LiBr and acetic acid. Calibrating the SEC system with poly(methyl methacrylate) of narrow polydispersity, molar masses were obtained that are in good agreement with data obtained by SEC-MALLS (multi-angle laser light scattering) and SEC measurements of methylated samples. The reproducibility and the robustness of the novel method were proven by running similar samples in three different laboratories and for an extended period of two weeks.

Abstract: Frontal polymerization is a mode of polymerization in which a localized zone of reaction propagates through the coupling of thermal diffusion and the Arrhenius dependence of the reaction rate. The dependence of the front propa- gation velocity on the initial composition has been determined in initially miscible binary systems of a free-radically cured diacrylate and an amine- or cationically cured epoxy resin. A minimum of the velocity as a function of the monomer mole fraction is observed if the two polymerizations occur independently. Excellent agreement with an analytical description was found with the diacrylate and an amine-cured epoxy but not for a diacrylate and a cationically cured one because of the effect of HCl impurities on the peroxide.

Abstract: We report the synthesis of a novel poly(p-phenylene-vinylene) derivative bearing dodecanoylsulfanyl side-groups (12COS-PPV). Good solubility in organic solvents was achieved. The average molecular weight was around 30 000, the energy gap 2.8 eV and the thermal stability up to 130°C. Doping with iodine vapours rose conductivity to 2·10 -6 S/cm. Gas sensors made from FeCl3-doped 12COS-PPV showed an unusual behaviour responding to only four of the eight different organic solvent vapours tested. Recoveries from the responses are not complete, but are reproducible and can be used to discriminate between the four solvents. Quantitative analyses are also possible since there is a good linear correlation between relative response and concentration.

Abstract: Abstract Low-density polyethylene (PE) containing nano-particulate clay was prepared after functionalization with maleic anhydride (MA) by reactive grafting in the presence of peroxide followed by blending of maleated PE with neat polymer in different concentrations. Four classes of composites were obtained: (i) exfoliated, (ii) intercalated, (iii) microcomposites, and (iv) intermediate of intercalated and microcomposites, as evidenced by wide-angle X-ray diffraction. All samples were kept for artificial UV irradiation (λ ≥ 290 nm) and for composting to study their photo- and bio-durability. Fourier-transform IR spectroscopy (FT-IR) and scanning electron microscopy were used to monitor the functional group and morphological changes, respectively, whereas biodurability was evaluated by measuring the weight loss. MA functionalization and nature of composites have detrimental effects on the overall durability of composites. Nanocomposites showed higher resistance than microcomposites during initial weathering and composting with a long induction period. The stability of nanocomposites decreases with time and overall durability was worse than of pristine polymer in both environments. It was concluded that the initial protection is due to the filler-generated long diffusion path, which decreases the oxygen diffusion through the matrix. The bio-durability of composites decreased with oxo-degradation. Biodegradation of PE nanocomposites during composting follows the mechanism described by Albertsson et al. as evidenced by FT-IR spectroscopy.

Abstract: Virtual polymeric materials were created and used in computer simu- lations to study their behavior under uniaxial loads. Both single-phase materials of amorphous chains and two-phase polymer liquid crystals (PLCs) have been simulated using the molecular dynamics method. This analysis enables a better understanding of the molecular deformation mechanisms in these materials. It was confirmed that chain uncoiling and chain slippage occur concurrently in the materials studied following predominantly a mechanism dependent on the spatial arrangement of the chains (such as their orientation). The presence of entangle- ments between chains constrains the mechanical response of the material. The presence of a rigid second phase dispersed in the flexible amorphous matrix influences the mechanical behavior and properties. The role of this phase in rein- forcement is dependent on its concentration and spatial distribution. However, this is achieved with the cost of increased material brittleness, as crack formation and propagation is favored. Results of our simulations are visualized in five animations. The deformation mechanisms taking place at the macromolecular level are not yet fully understood. It is generally accepted that a number of different mechanisms occur, depending on the structure of the material and the thermo-mechanical conditions associated to the imposed load. Several models were proposed to explain the specific mechanisms that allow the material to respond to an external load, such as chain uncoiling, chain sliding, crack formation and propagation, and splitting of lamellae in semi-crystalline polymers. However, the conditions and requirements for each mechanism to take place are far from established. To understand and to model those deformation mechanisms are fundamental steps for the prediction of the mechanical properties of polymers. Computer simulations have been performed with the aim of, among other topics, providing insights into this problem. The present paper reports computational results for simple polymer models under conditions that will enable the identification and study of some of the deformation mechanisms referred above.

Abstract: A removable pressure-sensitive adhesive was obtained by free-radical emulsion polymerization The product is a low-viscosity copolymer from different polar and apolar acrylic monomers consisting of microspheres of about 1 μm diameter 2-Ethylhexyl acrylate and isobutyl acrylate were used as non-polar constituents while acrylic acid and acrylamide provided the more polar constituents to regulate the cohesive force of the adhesive The amounts of initiator, water and emulsifier (nonylphenol) were varied to obtain the best adhesive properties at the given copolymer composition The resulting adhesive showed the desired balance of low tack and good adhesive strength in combination with a wide variety of substrates, which made it useful as a removable adhesive for many applications The product was characterised by viscometry, measurements of tack and peel strength, FTIR, DSC, and microscopy

Abstract: Abstract The effect of the addition of hydrocarbon oil on the mechanical behaviour of isotactic polypropylenes (iPPs) was examined. It was found that the oil molecules are completely dissolved in the amorphous region of iPP so that the blending lowers the glass transition temperature, Tg, of iPP. As a result, Young’s modulus of iPP/oil blends is dominated by the difference between the measurement temperature and Tg (ΔTg = T - Tg), independent of the oil content. The elongation at break is proportional to ΔTg, while the strength at break increases linearly with increasing tie-molecule fraction (which increases with decreasing oil content), being independent of ΔTg.

Abstract: Abstract The homopolymer of 4-chloromethylstyrene and its copolymers with styrene (in 1:3 and 1:1 mole ratio) were synthesized by bulk and solution freeradical polymerisations, respectively, at 70±1°C using α,α'-azoisobutyronitrile as an initiator. Highly sterically hindered tris(trimethylsilyl)methyl (Tsi) substituents were then covalently linked to the obtained homopolymer and copolymers. The polymers were characterized by IR, 1H NMR and 13C NMR, differential scanning calorimetry (DSC) and gel permeation chromatography. DSC showed that incorporation of Tsi substituents in the side chains of homopolymer and copolymers increases the rigidity of the polymers and, subsequently, their glass transition temperature.

Abstract: Abstract Graft copolymerization of methacrylonitrile (MAN) onto chitosan using ammonium persulfate (APS) as an initiator was studied. The reactions were carried out under argon atmosphere in a homogenous aqueous phase containing a small portion of acetic acid (AcOH). Evidence of graft copolymerization was obtained by FTIR spectroscopy, e.g., the appearance of nitrile in the spectrum of chitosan-graftpolymethacrylonitrile. The synthetic conditions were systematically optimized through studying the influential factors including temperature, as well as concentrations of initiator, MAN, AcOH, sodium dodecyl sulfate surfactant (SDS) and chitosan. The effects of individual factors were investigated by calculating and monitoring the variation of the grafting parameters, i.e., grafting ratio, grafting efficiency, add-on value, homopolymer content, and total conversion. The optimum condition was achieved at APS 0.0108 mol/L, MAN 0.201 mol/L, 80°C, SDS 0.0016 mol/L, chitosan 0.5 g, AcOH 0.0086 mol/L. The overall activation energy for the graft copolymerization was determined to be 7.3 kJ/mol.

Abstract: Abstract Effects of interactions at the interface on the morphologies of immiscible polymer blends were investigated using linear low-density polyethylene/poly(4- vinylphenol) (LLDPE/PVPh) and LLDPE/poly(methyl methacrylate) (LLDPE/PMMA) blends containing polyethylene-block-PMMA (PE-b-PMMA). In the case of LLDPE/ PMMA/PE-b-PMMA blends, in which there is no specific interaction at the interface, shapes of dispersed droplets were maintained and sizes were simply diminished with increasing PE-b-PMMA content. On the other hand, in the case of LLDPE/ PVPh/PE-b-PMMA, in which hydrogen bonds are formed between PVPh and PMMA blocks at the interface, we found irregularly undulated phase boundaries.

Abstract: Poly(vinyl acetate) (PVAc) composites were prepared by different approaches, namely (i) by mechanical mixing of untreated CaCO3 and PVAc, (ii) by mechanical mixing of CaCO3 pre-treated by irradiation polymerization in the presence of vinyl acetate, and (iii) by in situ emulsion polymerization of VAc in the presence of untreated CaCO3 nanofiller. The effects of nanoparticle pre-treatment and different approaches of preparation were correlated with changes in morphology and mechanical properties of PVAc composites using scanning electron microscopy and tensile tests. Untreated CaCO3 nanoparticles in the composite prepared by mechanical mixing provided strong interactions with the PVAc matrix. On the other hand, CaCO3 pre-treated nanoparticles decreased the interfacial interactions. For composites prepared by in situ polymerization a better dispersion of encapsulated nanoparticles was achieved and, as a result, a significant improvement of composite strength was observed. Interfacial interactions in nanocomposites can be changed by filler pre-treatment or by a suitable way of nanocomposite preparation.

Abstract: Polypropylene/poly(e-caprolactone) (PP/PCL) blends were prepared by melt mixing. The thermal behaviour of the blends was investigated using differential scanning calorimetry (DSC) and dynamical rheology in the solid state (RSA). Both non-isothermal and isothermal crystallizations were performed. The Avrami equation was applied to the latter case. DSC and RSA results demonstrated in agreement with morphological observations that PP/PCL blends are immiscible in the whole composition range. PP acts as a nucleating agent for PCL, and when PP forms the disperse phase, it crystallizes in a fractionated fashion. When PCL is the disperse phase, it exhibits an unexpected melting point depression after cooling at 10 °C/min. Such depression was not observed after isothermal crystallizations, indicating that under non-isothermal crystallization kinetic problems show up. Thus, global crystallization is governed by a competition between nucleation and diffusion, which depends on crystallization conditions and composition. Introduction Preparation of polymer blends has been extensively used to obtain new materials with useful properties. Usually, polymer blending is performed to reduce costs, to prepare materials with specific properties, to develop products with improved properties or to recycle industrial polymers. Unfortunately, most polymer blends are immiscible. Thus, it is imperative to have a good interfacial adhesion between the components to generate compatibility [1]. Although many commercial polymers are semicrystalline, studies on both crystallization and morphology of immiscible polymer blends containing at least one semicrystalline component are relatively scarce, especially if a polar component is involved [2,3]. The properties of semicrystalline blends depend strongly on their crystallinity, crystalline morphology and degree of dispersion. Several phenomena that influence the crystallization behaviour of the system have been reported. Among these phenomena, the following can be mentioned: nucleation and epitaxial crystallization [4-8], migration of heterogeneities from one phase towards the other [9,10], fractionated crystallization [11,12], rejection, engulfing or deformation of the dispersed phase by the growing superstructures of the matrix [13-15], and induction of crystal modifications [16]. Although crystallizability of the components induces immiscibility in the solid state in most cases, if a good

Abstract: Abstract Two classes of poly(amide-imide)s with mono- and bisazoaromatic chromophores in the side chain have been synthesized using one-step hightemperature polycondensation. The influence of the structures of the macromolecules on their properties was investigated. Preliminary results of the kinetics of holographic grating recording using 514.5 nm Ar+ laser light for chosen poly(amideimide) films are presented. The gratings were recorded using two linearly polarized beams with s-s or s-p configurations. For comparative purposes all experimental conditions (light intensity, two-beams intersection angle) were kept unchanged. It was found that time constants of grating build-up were significantly larger for polymers containing a chromophore with two azo groups when compared with the same polymers having a single azo group. On the other hand diffraction efficiencies were lower for polymers containing a chromophore with two azo groups than with a single azo group.

Abstract: Abstract Dynamic mechanical analysis (DMA) techniques are commonly applied to characterize polymer-based materials - but little if at all to characterize semiconductor thermoelectric (TE) materials. TE materials may be coupled with polymeric materials in advanced thermoelectric devices, and the knowledge of TE material properties will be useful in the choice of materials for future applications. We have obtained DMA results for both n-type and p-type bismuth telluride based TE materials. We find that tan δ values, indicative of viscoelastic energy dissipation modes, approach the values for glassy or semi-crystalline polymers, and are larger by more than a whole order of magnitude than the tan δ of structural metals. DMA thermal scans show clear hysteresis-type effects and a correlation with differential scanning calorimetry thermal transitions. DMA properties as a function of frequency are briefly discussed. Our results show that DMA techniques are useful in the evaluation of thermophysical and thermomechanical properties of these TE materials and of assembled coolers. The viscoelastic effects we report may provide a damping mechanism for severe stresses inherent to service conditions of the TE coolers.