Polymer Blends

In the present work novel nanocomposites have been prepared using sulfonated polystyrene-block-poly (ethylene-ran-butylene)-block-polystyrene (SPSPB) as matrix material. Two types of nanofiller were used i.e. neat graphite (G) and nanobifiller of graphite-polyoxometalate (G-POM). The series of SPSPB/G and SPSPB/G-POM nanocomposites were developed using simple solution method. The nanocomposites were incorporated with various filler content (0.01-0.5 wt. %). The SPSPB/G revealed flake-like morphology while SPSPB/G-POM nanocomposite depicted uniform dispersion of G-POM particles in the matrix. The tensile strength of sulfonated polystyrene-based matrix nanocomposites increased from 60.9 to 93.2 MPa with the nanobifiller addition of 0.01 to 0.5 wt. %. Thermal conductivity of SPSPB/G-POM 0.01-0.5 was higher (1.9-2.7 W/mK) than the SPSPB/G series. Higher electrical conductivity of 0.68 Scm -1 was also achieved with the 0.5 wt. % loading of G-POM.

Styrenic thermoplastic vulcanizates (STPV) consist of polypropylene (PP) and linear low density polyethylene (LLDPE) as the continuous phases and a crosslinked hydrogenated styrene block copolymer (SEBS) as the dispersed phase were prepared in an industrial scale using a corotating twin-screw extruder. Morphological study of the TPVs was carried out using a scanning electron microscope (SEM). Rheological study of the SEBS compounds carried with different content of 2,5-Dimethyl-2,5-di(tert-butylperoxy) hexane peroxide (0.5, 1, 2 and 4 wt. %). T90 appeared with 4 w% peroxide shows that curing has been completed. Effect of peroxide content (0.5 to 1.2 wt.%) on properties of the TPVs was led to an increase in tensile strength (from 5.6 to 7.4 MPa) and hardness to a certain extent (74 shore A). On the other hand, mechanical properties such as the elongation at break (from 592% to 284%), the melt flow index (MFI) (from 29.6 to 3.14 g/10 min at 190 °C, 10 kg) and tear strength (from 35 to 30 kg f/cm) are decreased. The compression set at low temperature (70 °C) is not changed so much, at high temperature (120 °C), while, is reduced due to higher curing (from 69% to 46%). Heat aging was carried out (at 85 °C for 168 h) on the TPVs which were prepared via the different content of peroxide (0.5 wt. % to 1.2 wt. %). It was found that the results of elongation and the hardness after aging have the lowest amount using 0.9 wt.% peroxide. However, the tensile strength after aging decreased with increasing the content of peroxide. As a result of increasing curing with increasing content of peroxide, the melting point of the prepared TPVs was disappears. The results of using triallylcyanurate (TAC) and bismaleimide (BMI) as a co-curing agent in peroxide curing indicate that all of the tensile strength, hardness and elongation at break (from 897 to 1082%) of the STPV were increased with BMI. Heat ageing study and compression set on the STPV with TAC was slightly raised compared to BMI. Also, the results of dynamic vulcanization on the properties of TPV based on SEBS/LLDPE/PP indicate that Crosslink density and gel content of TPV are close to that of EPDM rubber (fully crosslinked) and higher than that of TPE (without crosslinking). The results show that the tensile strength and density of the dynamically crosslinked blend have not changed significantly under peroxide curing.

In this work, we outline the development of a thermodynamically consistent microscopic model for a suspension of aggregating particles under arbitrary, inertia-less deformation. As a proof-of-concept, we show how the combination of a simplified population-balance-based description of the aggregating particle microstructure along with the use of the single-generator bracket description of nonequilibrium thermodynamics, which leads naturally to the formulation of the model equations. Notable elements of the model are a lognormal distribution for the aggregate size population, a population balance-based model of the aggregation and breakup processes and a conformation tensor-based viscoelastic description of the elastic network of the particle aggregates. The resulting example model is evaluated in steady and transient shear forces and elongational flows and shown to offer predictions that are consistent with observed rheological behavior of typical systems of aggregating particles. Ad...

Electrospinning is a process to produce versatile nanoscale fibers. In this process, synthetic and natural polymers can be combined to produce novel, blended materials with a range of physical, chemical, and biological properties. We electrospun biocompatible, blended fibrinogen:polycaprolactone (PCL) nanofibers with diameters ranging from 40 nm to 600 nm, at 25:75 and 75:25 blend ratios and determined their mechanical properties using a combined atomic force/optical microscopy technique. Fiber extensibility (breaking strain), elastic limit, and stress relaxation times depended on blend ratios but not fiber diameter. As the fibrinogen:PCL ratio increased from 25:75 to 75:25, extensibility decreased from 120% to 63% and elastic limit decreased from a range between 18% and 40% to a range between 12% and 27%. Stiffness-related properties, including the Young’s modulus, rupture stress, and the total and relaxed, elastic moduli (Kelvin model), strongly depended on fiber diameter. For dia...

In early 2022, the European Union delisted titanium dioxide (TiO 2) from the list of approved food additives, creating a need to explore potential alternatives to titanium dioxide. Given the concerns regarding TiO 2 and the possibility of similar restrictions to their use in tablet coatings, there is a need to evaluate alternatives to TiO 2 opacifiers in tablet coatings. Specifically, the alternative opacifiers are expected to influence the mechanical and adhesion properties of tablet coatings. The current study performs a comprehensive evaluation of six different commercially available titanium dioxide-free (TF) tablet coatings. The TF coatings contain calcium carbonate, rice starch and magnesium carbonate as opacifiers, with polyvinyl alcohol (PVA) or hydroxypropyl methylcellulose (HPMC) as the base polymers. Detailed measurements of drying stress, mechanical strength, and adhesion testing were conducted to evaluate their suitability as pharmaceutical coatings. The TF coatings resulted in drying stresses that were comparable to those observed for TiO 2 coatings. However, the tensile strength and Young's modulus of all TF coatings, except one, were observed to be lower, indicating a relatively poor mechanical strength. Adhesive strength of TF coatings was similar to that of TiO 2 coatings, with waxy tablets exhibiting lower adhesion strength due to higher hydrophobicity. In summary, the HPMC-HPC-based TF coating showed superior mechanical strength and comparable adhesive properties when compared to TiO 2 coatings. This positions it as a viable alternative to TiO 2 among the coatings tested. In contrast, all other TF coatings did not achieve the performance levels of the TiO 2 coatings.

In this thesis, I describe experiments that provide a new and deeper understanding of factors that affect polymer diffusion in acrylic latex films. This is the step that leads to the growth of mechanical properties of these films. Polymer diffusion was studied by fluorescence resonance energy transfer (FRET) in films prepared from dye-labeled latex particles. Poly(n-butyl acrylate-co-methyl methacrylate) [P(BA-MMA)] was chosen for the study of copolymer composition on the polymer diffusion rate. Four sets of P(BA-MMA) copolymers were prepared from various weight ratios of BA/MMA. Polymer diffusion was monitored as a function of annealing temperature, and apparent diffusion coefficients (D app ) were calculated from the FRET data, using a simple diffusion model. The temperature dependence of polymer dynamics (G', G") obtained by linear rheology measurements is in good agreement with the temperature dependence of D app . Increasing the BA content of the copolymer led to an apparent increase in long-chain branching, which is reflected in both the time dependence of D app and in the dynamic moduli measurements. To study the effect of branching on polymer diffusion rates, latex particles comprised of branched poly(n-butyl methacrylate) (PBMA) were prepared. The degree of branching was controlled by adding various amounts of bisphenol A dimethacrylate as a branching agent, plus First, I would like to express my greatest appreciation to Professor Mitchell A. Winnik for his guidance, encouragement, and support during my doctoral study. His insight, kindness, humor, and knowledge truly impress and affect me. From him I have learned not only how to work, but also how to live. He is far beyond a research supervisor. Second, I want to thank my industry supervisor, Dr. Willie Lau, who gave me this great opportunity to work with Rohm and Haas Company, a world's leading company in coatings industry. Without his continuous help my research could not be carried out smoothly. Third, my appreciation will go to my research committee members, Professor Michael Georges, Professor Eugenia Kumacheva, Professor Gilbert Walker, and Professor Tim Bender, for their advices and help on my research. Fourth, I give my appreciation to my colleagues, especially Dr. Jeffrey C. Haley and Dr. Walter F. Schroeder. Working with Jeff was very enjoyable since he is smart, creative and humorous. Walter is an excellent research partner with highly reliance. I would also thank Dr.

This study investigates the mechanical properties of vulcanizates based on SRI-3 rubber with the addition of a natural biopolymer derived from grape leaves. The aim of the research was to develop composite materials with improved performance characteristics and enhanced environmental safety by utilizing renewable plant-based components. Various curing methods for SKI-3-based rubber compounds modified with the biopolymer were examined, including classical sulfur vulcanization. The results showed that the main vulcanization parameterssuch as scorch time, tensile modulus, and total vulcanization timeremain comparable across the studied systems. The use of grape leaf as a modifier demonstrated that the resulting vulcanizates possess very high mechanical properties. The tensile strength reaches 24 MPa, which is 1.5 times higher than that of standard SKI-3-based rubber. The study also revealed that the residual elongation of the developed rubber is only 2%.

A. X-ray diffraction (XRD) analysis of the stretched P(VDF-HFP) film The wide angle XRD measurement of the stretched P(VDF-HFP) (88/12) copolymer film with the thickness of 8 µm is presented in Figure S1a. The copolymer film was mechanically stretched by 400 %, which converted a large fraction of the non-polar α phase to the polar β phase. 1 The prominent peak at 2θ = 20.3º comes from the (110/200) plane of the β phase. Other characteristic peak positions (2θ) are 17.6º (100), 18.5º (020), 19.9º (110) for α phase and 36.5º (020) for β phase. Figure S1b shows the azimuthal angle (ϕ) distribution of XRD intensity of the composite (110/200) plane of the β phase. The azimuthal angle ϕ = 0 º corresponds to the stretching direction and ϕ = 90 o is perpendicular to the stretching direction of the film plane. The data indicates that the β crystalline domains are aligned along the stretch direction. 2

More a decade ago, Hashimoto and co-workers have first investigated the phase behavior of ternary mixtures made of two neutral linear homopolymers A/B and the corresponding diblock copolymer. A few years later, this study has been extended by Benmouna et al. to similar systems composed of cyclic chains. These authors have found that, depending on the concentration of copolymer, the interplay between macrophase and microphase separation transitions can take place. In the other hand, (...)

This work incorporated hexamethylene diamine and terephthalic acid, namely 6T, into typical polymerization processes of Nylon 6 and Nylon 66 to form Nylon 6/6T and Nylon 66/6T copolymers, respectively. The WAXD results showed that as the amount of 6T increased to 10 mol%, all of the Nylon 6/6T copolymers transferred from ␣-form to ␥-form. The DSC measurement revealed that the equilibrium melting point of Nylon 6/6T decreased as the amount of 6T increased. Moreover, the crystallization rate k decreased with the 6T content in Nylon 6/6T copolymers, and dropped greatly when the addition of 6T increased over 7 mol%. In contrast, due to the similar molecular chain lengths of Nylon 66 and 6T, the WAXD results of Nylon 66/6T exhibited little crystal difference as the addition of 6T varied from 0 to 30 mol%. The equilibrium melting point of Nylon 66/6T remained constant, proving that Nylon 66/6T is isomorphous.

Pristine samples of a polymer blend of polyvinylpyrrolidone (PVP)/ polyvinyl alcohol (PVA)/ chitosan filled with different concentrations of silver nanoparticles (AgNPs) were prepared using the casting method. The samples were then examined using various physical and antibacterial characterization techniques. Characterization studies showed that the blend provides a uniform and controlled distribution of AgNPs inside the polymeric matrix without the addition of any more stabilizers. The mean particle size for green and laser-ablated AgNPs was found to be 50 nm according to transmission electron microscopy (TEM) studies. Fourier transforms infrared (FTIR) studies showed the presence of characteristic main peaks corresponding to the vibrational groups which characterize the prepared samples. The interactions between the AgNPs and the blend were marked by changes in the intensity of vibrational peaks and spectral positions. X-ray diffraction (XRD) confirmed the structural modification ...

Common fiber reinforced polymer (FRP) structures contain only one matrix system in the entire part. Hence, the selection of the matrix material is a compromise between the most dominant requirements. To overcome this compromise, the hybrid-matrix approach is investigated using polyurethane (PU) elastomer and thermoset matrix material. The approach offers the possibility to locally integrate different matrices into one FRP structure using a liquid composite molding (LCM) process. To prove the feasibility, co-infiltration experiments were performed to evaluate suitable process concepts. For the process assessment the merging and mixing area is analyzed regarding material transition and void content via micrographs. In order to analyze the matrix compatibility and properties in the merging and mixing area of the different matrix systems the glass transition temperature (TG) and flexural properties of elastomer/thermoset PU blends are determined using Differential Scanning Calorimetry (DSC) and Dynamic Mechanical Analysis (DMA). The experimental results prove that the flow front velocities can be slowed down and aligned along a predefined merging area with an out-of-plane parting line. The comparison of the void content in the different composite areas indicates that the material quality is not affected by the merging and mixing of the two matrix materials during the co-infusion process. The TG and the flexural storage modulus results show that the selected PU resins are miscible and that a gradual transition of the mechanical properties related to the degree of mixing exists.

This study focused on the performance properties of flax blended knitted fabrics. Firstly, fabrics were knitted using flax/recycled polyester/polyester yarns developed in different blend ratios. Physical tests such as dimensional properties, fastness tests and bursting strength of the obtained fabrics were carried out. Then, comfort properties were examined in terms of drying rate and air permeability. In conclusion, while the best fabric performance was obtained in single jersey and pique quality, it was determined that flaxcontaining yarns were not suitable for rib quality. Increasing the flax ratio has a negative impact on fabric performance, and the optimum flax ratio to be used has been determined as 20%.

The transient and steady-state elongational viscosity data of three bidisperse polystyrene blends were investigated recently by Nielsen et al. ͓J. Rheol. 50, 453-476 ͑2006͔͒. The blends contain a monodisperse high molar mass component ͑M L = 390 kg/ mol͒ in a matrix of a monodisperse small molar mass component ͑either M S = 103 kg/ mol or M S =52 kg/ mol at two different weight fractions͒. The experimental data are analyzed in the framework of the molecular stress function model of Wagner et al. ͓J. Rheol. 49, 1317-1327 ͑2005͔͒, which is based on the assumption of a strain-dependent tube diameter and the interchain pressure term of Marrucci and Ianniruberto ͓Macromolecules 37, 3934-3942 ͑2004͔͒. The dilution of the long chains in the matrix of the short chains is identified as the origin of a drastic increase in the tube-diameter relaxation time of the long chains, leading to a large stretching potential of the long-chain component and an increasing steady-state elongational viscosity with increasing strain rate. In addition, in the dilution regime, a transition from affine chain stretch to nonaffine tube squeeze with decreasing strain rate is identified. The dilution regime ends at a critical strain rate, when the tube diameter of the supertubes created by the interaction of the long chains among themselves, is reduced by deformation to the tube diameter of the bulk. A nonlinear extension of the basic double reptation concept is developed comprising all of these different phenomena, and allowing ͑albeit by use of a͒

The transient and steady-state elongational viscosity data of three bidisperse polystyrene blends were investigated recently by Nielsen et al. ͓J. Rheol. 50, 453-476 ͑2006͔͒. The blends contain a monodisperse high molar mass component ͑M L = 390 kg/ mol͒ in a matrix of a monodisperse small molar mass component ͑either M S = 103 kg/ mol or M S =52 kg/ mol at two different weight fractions͒. The experimental data are analyzed in the framework of the molecular stress function model of Wagner et al. ͓J. Rheol. 49, 1317-1327 ͑2005͔͒, which is based on the assumption of a strain-dependent tube diameter and the interchain pressure term of Marrucci and Ianniruberto ͓Macromolecules 37, 3934-3942 ͑2004͔͒. The dilution of the long chains in the matrix of the short chains is identified as the origin of a drastic increase in the tube-diameter relaxation time of the long chains, leading to a large stretching potential of the long-chain component and an increasing steady-state elongational viscosity with increasing strain rate. In addition, in the dilution regime, a transition from affine chain stretch to nonaffine tube squeeze with decreasing strain rate is identified. The dilution regime ends at a critical strain rate, when the tube diameter of the supertubes created by the interaction of the long chains among themselves, is reduced by deformation to the tube diameter of the bulk. A nonlinear extension of the basic double reptation concept is developed comprising all of these different phenomena, and allowing ͑albeit by use of a͒

Morphology development of polytetrafluoroethylene (PTFE) caused by applied flow history in molten isotactic polypropylene (PP) is investigated, employing a cone-and-plate rheometer and a capillary rheometer as mixing devices. Since the flow history is applied at 190 °C, PTFE is in the solid state whereas PP is in the molten state. It is found that primary PTFE particles tend to be agglomerated together by mechanical interlocking. Then they are fragmented into fibers by hydrodynamic force with reorganization process of crystalline phase. The diameter of the fragmented fibers is the same as that of the original ellipsoidal particles. Further, fine fibers whose diameter is in the range from 50 to 100 nm are also generated by yielding behavior of the particles. The prolonged shearing leads to a large number of fibers, although the diameter and length are hardly affected by the exposure time of shearing and shear stress. Moreover, the flow type (i.e., drag or pressure flow) does not affe...

Polymers have significantly assisted to the advancement of the drug delivery devices by adjusting the drug release at consistent rates over extended durations, facilitating cyclic administration, and targeting to the desired site. Polymers are frequently utilized as taste-masking, stabilizing, and proactive agents. The key characteristics that render polymers appealing options for drug delivery include their safety, effectiveness, hydrophilicity, non-immunogenicity, biological inertness, favourable pharmaceutical kinetics, and the presence of functional groups that facilitate covalent crosslinking, targeting ligands, or copolymer formation. Natural polymers that are more commonly used, like arginine, collagen, chitosan, and carrageenans are discussed for their possible application in polymeric drug delivery systems. Synthetic polymers exhibit elevated immunogenicity, limiting their viability for prolonged application. Non-biodegradable polymers necessitate subsequent removal post-drug release at the intended site. Progress in polymer science has made possible in the emergence of various innovative drug delivery systems, including hydrogels, liposomes, nanoparticles, micelles, patches, implants, and others. Biodegradable polymers have garnered considerable interest because they can degrade into non-toxic monomers, enabling sustained drug release from biodegradable polymer-based controlled-release devices. This review delves into the commonly used synthetic and natural polymers that are used in drug delivery, consideration of selection of polymers and recent advancement in polymer research.

In this study, the synthesis of polyethylenes has been carried out with titanium-magnesium supported Ziegler-Natta catalysts in laboratory-scale reactors. A correlation of different polymerization conditions with thermal and mechanical properties of polyethylenes has been established. It is seen that there is lowering of molecular weight (Mw), polymer yield, and catalyst activity at high hydrogen pressure and high temperature. The Mw, polymer yield, and catalyst activity are improved with the increase in ethylene pressure. Dynamic mechanical analysis (DMA) results show that the increase in temperature and hydrogen pressure decreases storage modulus. The samples with higher Mw showed high activation energy. The melting point decreases with the increase in hydrogen pressure but increases slightly with the increase in ethylene pressure. It is seen that the increase in reaction temperature, ethylene pressure, and hydrogen pressure leads to an increase in crystallinity. The tensile modul...

Copolymers of methyl acrylate were grafted onto low-molecular-weight polyethylene in the presence of benzoyl peroxide in o-xylene. The formation of these copolymers was confirmed by functional analysis of the ether groups and Fourier-transform infrared spectroscopy. Various synthesis patterns were demonstrated, which furnished grafted copolymers with a wide range of compositions. X-ray diffraction analysis showed that grafting led to changes in the crystalline structure of low-molecular-weight polyethylene. The grafting sequences of the methyl acrylate units may disrupt the order of the crystalline planes in polyethylene, and with an increase in their content, the crystalline phase in polyethylene becomes less prominent. These copolymers can be used as compatibilizers for CB-filled polyethylene (CB: carbon black). The effect of the grafted copolymers on the properties of high-density polyethylene composites containing CB was evaluated. The composites of polyethylene and the grafted copolymers exhibited enhanced thermal stability, plausibly associated with a decrease in the average size of the CB particles.

and affect the phase behaviour of polymer-polymer mixtures . In this work, the phase behaviour and miscibility regions of hydrogen bonded polymer mixtures are calculated by a new model based on the lattice fluid theory of mixtures . In this model, the compressibility or free volume effect of the mixture which is originated from empty lattice sites is considered by introducing a new correlation for the number of vacant sites . The spinodal curves are calculated for the mixtures and it is shown that as expected from the theory, higher compressibility causes lower stability and consequently the phase separation.

Chain mobility in multiphase polymeric materials is studied by thermally stimulated depolarization currents and dielectric spectroscopy in poly(styrene)-h-poly(butadiene)-h-poly(t-caprolactone) triblock copolymers and poly(carbonale)/poly(t-caprolactone) blends. The variation in the relaxation time distribution of the dielectrically active components and in the number of orientable dipoles in the amorphous phases of these materials is interpreted as the result of the existence of a rigid amorphous phase constrained by the crystalline regions or in the case of the blends by a phase segregation which takes place when the crystalli7.ation process of the blend components advances. The mean relaxation times for the secondary and segmental motions are not affected when the phases are segregated.

The high temperature dielectric relaxation process, observed above the glass transition temperature in poly(e-caprolactone) is studied by Thermally Stimulated Depolarization Currents experiments. The characterization is made by using the windowing polarization technique, decomposing the complex high temperature relaxation into Debye-like peaks. The profile of each peak is then analyzed by using a general kinetic order model, and the origin of the complex relaxation is discussed through the analysis of the parameters obtained from the best fit to the model. The distribution of the trap depths is obtained and their activation energies is found to vary from 0.8 to 1.2 eV. The space charge accumulation is mainly responsible for this relaxation mode in poly(e-caprolactone).

Dielectric relaxations of polycarbonate (PC) and poly(-caprolactone) (PCL) blends that were thought to be completely homogeneous in the amorphous phase from many previous calorimetric studies are performed by using the thermally stimulated depolarization currents technique. Samples kept for 18 months at room temperature were compression-molded and then either quenched or slowly cooled. Quenched samples evidenced a phase separation for the 20/80 PC/PCL composition and the existence of continuous concentration fluctuations for other blend compositions. The slowly cooled samples from the melt exhibited an increase of the crystallinity degree for both blend components, together with a segregation of a predominantly rich PCL phase and the appearance of high-temperature relaxations attributed to interfacial polarization. These findings are confirmed by new calorimetric results on the same blends and by transmission electron microscopy. The spherulitic growth rate also points to the coexistence of two phases which are not completely immiscible but remain separated, each one being rich in one of the blend components. The phase separation of the PC/PCL blends increases with long storage times at room temperature. The driving force behind this segregation process seems to be the slow crystallization of the PCL component during storage. Once the blends have undergone phase separation, only extrusion in the melt or solution mixing can increase their miscibility.

Thermal sampling peaks recorded after windowing polarization are studied for the segmental mode in poly͑⑀-caprolactone͒. Also, numerical decompositions of the global thermally stimulated depolarization current peak into pure Debye contributions are performed with direct signal analysis ͑DSA͒ and simulated annealing direct signal analysis procedures for Arrhenius and Vogel-Tammann-Fulcher ͑VTF͒ temperature dependences, respectively. It is found that the results between the experimental and the numerical procedures agree very well and the approximations made in the analysis of the experimental curves are thus validated, despite the unphysical values for the relaxation parameters found by both methods when using Arrhenius relaxation times. On the contrary, when VTF relaxation times are used for the numerical decomposition, agreement is found with the results of isothermal dielectric absorption as a function of frequency, together with reasonable values for reorientation energies, pre-exponential factors and VTF temperature. Thermal sampling and DSA also compare well when studying the departure from the zero-entropy line which indicates the onset of a cooperative character in the dynamics of molecular motion. Compensation is found whenever the primary relaxation is analyzed with Arrhenius or Eyring relaxation times and does not appear when VTF relaxation times are used in the numerical decomposition.

In this work viscoelastic polymeric damping material was studied for its ability to damp out vibrations in wood structures (houses). This is accomplished by placing a thin layer of the material between wood stud and sheathing material. Damping performance of three individual polymers was obtained and compared to two types of blends of the materials. Placing the strips of material next to each other (parallel arrangement for shear) rather than on top of each other (series arrangement for shear), gave improved damping results over a wider temperature range relative to the single polymers. This is attributed to the widening of the damping peak by combining the materials. This is expected to be useful in earthquake-resistant wooden structures, such as housing, by delaying collapse and by absorbing energy, thereby increasing likelihood of saving the lives of the inhabitants.

In this work viscoelastic polymeric damping material was studied for its ability to damp out vibrations in wood structures (houses). This is accomplished by placing a thin layer of the material between wood stud and sheathing material. Damping performance of three individual polymers was obtained and compared to two types of blends of the materials. Placing the strips of material next to each other (parallel arrangement for shear) rather than on top of each other (series arrangement for shear), gave improved damping results over a wider temperature range relative to the single polymers. This is attributed to the widening of the damping peak by combining the materials. This is expected to be useful in earthquake-resistant wooden structures, such as housing, by delaying collapse and by absorbing energy, thereby increasing likelihood of saving the lives of the inhabitants.

In this work, pure PVC films and PVC-PVDF-HFP mix films were made utilizing the solution casting process with variable wt% of PVC to PVDF-HFP. FTIR, XRD, and DSC techniques were used to evaluate the structural, morphological, and miscibility properties of the films. FTIR and XRD data verified molecular interactions between the two polymers, highlighting the occurrence of the α-phase of PVDF-HFP in the blends. The research also showed that when the PVDF-HFP content increased, so the crystallinity in the samples. Furthermore, both experimental and theoretical DSC data showed a decrease in the glass transition temperature (Tg) as the PVDF-HFP content in the mix rose.

Introduction 2. Synthesis of Model Macromolecules 3. Interaction of Synthetic Poly(alkylene phosphates) with Metal Cations 4. Ionic Interactions 5. Ionic-Nonionic Dihydrophilic Block Copolymers (with Phosphate Units) and Their Interaction with Inorganic Particles 6. Interaction of Poly(alkylene phosphates) with Polyaniline Chapter 2 COMBINATIONS OF TRANSITION METAL CATALYSTS FOR REACTOR BLENDING………………………………………….

Round robin tests carried out under the direction of the Technical Committee 4 of the European Structural Integrity Society (ESIS TC4) have shown that, for determining the fracture resistance of ductile polymers at low loading rates, the multi-specimen methodology based on the construction of the material crack growth resistance curve often does not provide reliable data due to the uncertainties associated with the measurement of crack advancement (Da). With the aim of strengthening this multi-specimen methodology, the ESIS TC4 attention has been recently focused on the analysis of a testing scheme based on the load separation criterion, which does not require the measurement of Da. The present work gives the results of a multi-laboratory round-robin testing exercise carried out by ESIS TC4 in order to assess the degree of reproducibility of the fracture parameters obtainable with the application of this load separation criterion based testing scheme. Encouraging results have been obtained.

3D plotting of micro-extruded filaments is a promising method for the additive manufacturing of porous scaffolds (for tissue engineering) in thermoplastic polymers. A much investigated polymer for degradable scaffolds is poly-εcaprolactone (PCL). One of the remaining issues with the material is its inherent hydrophilicity, which leads to nonspecific protein adsorption. Specifically for cardiovascular applications, it has also been found that PCL is insufficiently flexible to mimic the mechanic-elastic behavior of the natural tissue. Earlier research has shown that blending with low molecular weight poly-ethylene-oxide (PEO) may offer an improvement in terms of both hydrophilicity and flexibility. Until now, solution-based blending has been used as a manufacturing method for these blends, since PCL and PEO are largely immiscible in the melt. This, however, is tedious work which yields only a few grams of material at a time. Therefore, in the current research, a method has been developed for the bulk compounding of PCL-PEO blends, using a twin-screw extruder. The manufactured blends were evaluated for composition, dispersion of the PEO and crystalline morphology. It was found that by re-compounding the blends after the first extrusion step, a good dispersion of the PEO within the PCL matrix was achieved.

The main goal of this research is to study the development of crystalline morphology and compare it to various mechanical properties of microfibrillar composites (MFCs) based on polypropylene (PP) and poly(ethylene terephthalate) (PET), by adding a functional compatibilizer and a non-functional rubber in two different steps in the processing sequence. The MFCs were prepared at a weight ratio of 80/20 PP/PET by twin screw extrusion followed by cold drawing and injection moulding. The non-functionalized polyolefin-based elastomer (POE) and the functional compatibilizer (i.e., POE grafted with maleic anhydride (POE-g-MA)) were added in a fixed weight percentage at two stages: during extrusion or during injection moulding. The morphology observations showed differences in crystalline structure, and the PP spherulite size was reduced in all MFCs due to the presence of PET fibrils. Their relationship with the mechanical performances of the composite was studied by tensile and impact tests. Adding the functional compatibilizer during extrusions showed better mechanical properties compared to MFCs. Overall, a clear relationship was identified between processing, structure and properties.

The main goal of this research is to study the development of crystalline morphology and compare it to various mechanical properties of microfibrillar composites (MFCs) based on polypropylene (PP) and poly(ethylene terephthalate) (PET), by adding a functional compatibilizer and a non-functional rubber in two different steps in the processing sequence. The MFCs were prepared at a weight ratio of 80/20 PP/PET by twin screw extrusion followed by cold drawing and injection moulding. The non-functionalized polyolefin-based elastomer (POE) and the functional compatibilizer (i.e., POE grafted with maleic anhydride (POE-g-MA)) were added in a fixed weight percentage at two stages: during extrusion or during injection moulding. The morphology observations showed differences in crystalline structure, and the PP spherulite size was reduced in all MFCs due to the presence of PET fibrils. Their relationship with the mechanical performances of the composite was studied by tensile and impact tests. Adding the functional compatibilizer during extrusions showed better mechanical properties compared to MFCs. Overall, a clear relationship was identified between processing, structure and properties.

Recently, interest in products with aging/abrasion effects has been increasing. These effects are commonly applied to t-shirts and sweatshirts produced with different knitting structures. Within the scope of the study, knitted garments with different structures were subjected to ozonation using varying working parameters (processing time, ozone strength and pH). Three types of knitted structures were used: single jersey, pique, and fleece. The dimensional properties, color difference, water and perspiration fastness values of the ozonated samples were examined. According to the results, it was determined that ozone washing did not affect the fastness values. However, the ozone washing process caused some loss in bursting strength. Then, the most effective parameter in the ozone washing process was analyzed using SPSS statistical software. The results showed that the color fading values of the samples increased with higher ozone strength and longer processing times and with lower pH values. It was also found that the most effective parameters for the fading effect were processing time, ozone strength and pH, respectively.

The biodegradability, morphology, and mechanical properties of composite materials consisting of acrylic acid-grafted poly(hydroxyalkanoate) (PHA-g-AA) and rice husk (RH) were evaluated. Composites containing PHA-g-AA (PHA-g-AA/RH) exhibited noticeably superior mechanical properties compared with those of PHA/RH because of greater compatibility with RH. The dispersion of RH in the PHA-g-AA matrix was homogeneous because of ester formation and the consequent creation of branched and crosslinked macromolecules, between the carboxyl groups of PHAg-AA and hydroxyl groups in RH. The water resistance of PHA-g-AA/RH was higher than that of PHA/RH, although the weight loss of composites buried in soil compost indicated that both were biodegradable, especially at high levels of RH substitution. After 60 days, the weight loss of the PHA-g-AA/ RH (40 wt%) composite was greater than 90 %. PHA/RH exhibited a weight loss of approximately 4-8 wt% more than PHA-g-AA/RH. The PHA/RH and PHA-g-AA/RH composites were more biodegradable than pure PHA, which implies a strong connection between RH content and biodegradability.

A facile method to prepare polyaniline (PAn) micro-rods in dimethyl fomamide (DMF) solution was developed. The structure of the polyaniline micro-rods was determined by the Transmission electron microscopy (TEM), Scanning electron microscopy (SEM), X-ray diffraction patterns (XRD), FT-IR and UV-vis spectroscopy. They showed that the average length and diameter of the polyaniline microrods were about 15 m and 6 m, respectively. At the same time, the effect of reaction solution and polystyrene (PS) concentration on the formation and morphology of the polyaniline micro-rods was further investigated in detail. The result showed that the reaction solution DMF was the key factor for the formation of polyaniline micro-rods and the morphology of polyaniline micro-rods could be controlled by PS concentration. Moreover, the electrical and microwave absorption properties of rod-like products were also investigated. And the result showed that the short micro-rod products had higher electrical and microwave absorption properties compared with long micro-rod products.

Electrospinning is a process to produce versatile nanoscale fibers. In this process, synthetic and natural polymers can be combined to produce novel, blended materials with a range of physical, chemical, and biological properties. We electrospun biocompatible, blended fibrinogen:polycaprolactone (PCL) nanofibers with diameters ranging from 40 nm to 600 nm, at 25:75 and 75:25 blend ratios and determined their mechanical properties using a combined atomic force/optical microscopy technique. Fiber extensibility (breaking strain), elastic limit, and stress relaxation times depended on blend ratios but not fiber diameter. As the fibrinogen:PCL ratio increased from 25:75 to 75:25, extensibility decreased from 120% to 63% and elastic limit decreased from a range between 18% and 40% to a range between 12% and 27%. Stiffness-related properties, including the Young's modulus, rupture stress, and the total and relaxed, elastic moduli (Kelvin model), strongly depended on fiber diameter. For diameters less than 150 nm, these stiffness-related quantities varied approximately as D-2 ; above 300 nm the diameter dependence leveled off. 50 nm fibers were five-ten times stiffer than 300 nm fibers. These findings indicate that fiber diameter, in addition to fiber material, critically affects nanofiber properties. Drawing on previously published data, a summary of the mechanical properties for fibrinogen:PCL nanofibers with ratios of 100:0, 75:25, 50:50, 25:75 and 0:100 is provided.

ABSTRACTWe have studied star-branched polymers in solution under various labelling and contrast matching conditions by small angle neutron scattering and neutron spin echo spectroscopy. We have investigated the relation between the static and dynamic partial structure factors of the variously labeled star polymers. The system of interest is a set of solutions containing 12-arm star branched polyisoprene of arm-molecular weight of 8000, and two polystyrene 12-arm stars, one fully labelled, the other with one arm labelled. The polyisoprene star polymer arms consisted of diblock copolymers, half-deuterated, and half-protonated. Measurements were performed on a center-deuterated star in a contrasted matching deuterated solvent (shell contrast), and on a reverse labelled star with core contrast. We have also studied a solution with the solvent matched the average star scattering length density and solutions containing identical stars with protonated homopolymers. It is found that in the ...

In industrial loop reactors, for catalytic ethylene (co)polymerization, the heat produced by polymerization can result in temperature and pressure increase, which in turn can lead to reactor breakage, explosion, and consequent release of toxic/flammable fluids in the environment. To predict the reactor temperature and pressure during ethylene (co)polymerization and assess the performance of presure safety valves (PSVs) in response to emergency accidents, an integrated mathematical approach is followed including catalyst kinetics, thermodynamics, and transport properties modeling. A catalytic ethylene (co)polymerization kinetic model is used to predict the catalyst activity variation with respect to reactor temperature and the heat produced by the polymerization reaction during a reaction runaway. The Sanchez-Lacombe equation of state (SL EOS) is utilized in order to predict the reactor pressure for different slurry mixture compositions and the slurry densities at different temperatures, pressures and solids weight fractions. Dynamic macroscopic mass and energy balances are derived to calculate the dynamic evolution of concentrations of the various molecular species as well as the temperature changes in the loop reactor. The model can predict the temperature and pressure increase rates and the maximum flow rate at the PSVs during the runaway.

eLearning may enrich the mental representations, save energy, time and resources.Both in the case of the primary school in Romania and the primary school abroad, the eletronic teaching materials and tools are capitalized. They are integrated in traditional lessons or final exams. Because the equipment with electronic tools is not a problem in our country anymore, the research is based on the analysis of the information obtained through questionnaires. These questionnaires are designed according to the opinion questionnaires realized by G. H. Gallup, respecting in the same time the conditions regarding the length of the questionnaire, its design, avoiding the "halo" effect in the questionnaires applied on the primary school teachers, parents and students. Consequently, this paper aims to: 1. Analyse the usage degree of some eLearning tools in the Romanian primary school, degree which rises or decreases together with other variable involved in the researching process; 2. To answer the following questions: what eLearning tools are involved in the teaching-learning process today and in what degree? What is the connection between the educational degree and the usage degree of the eLearning tools? To what extend do they help anyone keep in mind the information? To what extend do they simplify the teaching process? To what extend do the actors involved in the teaching-learning process consider that the working style may be modified and if they may lead to addiction? 3. To present, in the end, if and how these eLearning tools respect the principles of teaching Mathematics.

This paper presents research work on the characteristics and micro mechanism of strain whitening of a thermoplastic olefin material. Systematic tensile tests have been carried out to investigate the relation between strain whitening extent and external factors, including the deformation employed and the environmental temperature. A new optical method has been developed for the measurement of strain on polymer tensile samples. Applying this method relation between whitening level (grey level change) and strain has been studied. A new concept of 'strain whitening sensitivity' has been proposed and defined as the strain whitening induced by unit deformation or strain. Non-monotonic relation between whitening level and strain has been found. Strained and fractured samples were observed with A JEOL 5800 LV SEM for the micro mechanism investigation. The change of microstructure on the sample surface has been extensively observed and the combined effects of small ridges and micro-voids on the scattering efficiency of the strained surface were regarded as reasons for the non-monotonic relation between whitening level and strain.

Two types of chitosan (CS), a and b, were blended with different concentrations of starch and cast to obtain films. The addition of 1% glycerol was used as a plasticizer to increase film flexibility. The properties of the obtained films were studied by positron annihilation lifetime spectroscopy, X-ray diffraction, and scanning electron microscopy. The results indicate that pure b-CS had smaller size free-volume holes with high fractions than pure a-CS; this was attributed to the difference in bonding of main chains in b-CS. The addition of starch (>20% up to 50%) reduced the size of the free-volume holes and increased their fraction because of the close packing of chain segments. The effect of 1% glycerol to the CS starch blends indicated that some modification took place. V C 2010

The optimal combination of input process parameters to enhance polyamide 12 (PA12) powder particle size distributions and improve thermal properties for efficient laser sintering was investigated in this research using response surface methodology (RSM). The desirability function approach was adopted to establish an optimum parameter combination for achieving maximum melting enthalpy (ΔHm) and optimum particle size distribution (PSD). According to the analysis of variance (ANOVA), pellet mass, solvent concentration, and temperature had the most significant impact on determining the optimal enthalpy and PSD of the PA12 polymer for the thermally induced phase separation (TIPS) process. The validation report of predicted data was symmetrically distributed and extremely near to the experimental data of output responses. The most favorable input operating parameters for maximum PA12 powder production via TIPS were established at approximately 6.97 g PA12 pellet mass, 27.93 mL (DMAc), 242.40 rpm (agitation), and a temperature of 140.78 • C, respectively, while the optimal melting enthalpy and PSD were 35.74 J/g and 57.59 μm, adequate enough for laser sinterability of the polymer powder.

The interfacial structure and properties of immiscible deuterated polystyrene (dPS)/epoxy bilayer films were investigated with neutron reflectivity as functions of the composition of the epoxy layer, the thickness of the dPS layer, and the annealing time. We have found that the interfacial width and its growth rate depend strongly on the compositions of the epoxy layer but only weakly on the thickness of the dPS layer. The effect of the resin/crosslinker composition on the interfacial width and its growth rate is likely due to the different near‐surface structures that result for different epoxy stoichiometries. For an ultra‐thin dPS film (thickness = 2Rg), the data suggest a slight suppression of the growth of the interfacial width that could be due to confinement effects for the long‐chain molecules such as have been previously reported for a thickness of less than approximately 4Rg, where Rg is the radius of gyration of polymer molecules. © 2002 Wiley Periodicals, Inc. J Polym Sc...

Thermoplastic composites and their blends were compounded with a twin -screw extruder and injection moulded. The effect of the addition of silane treated and untreated talc as filler on thermal properties of polymer composites and TPU/PP blends were investigated. Organosilane (3-glycidoxyoxypropyl-metoxy silane) coupling agent was used to treat talc in order to improve the affinity relative between the filler and the composite as well as TPU/PP blends. The obtained results showed that the thermal properties of the talc filled TPU,PP composites and TPU/PP blends were improved with the addition of talc. The DMA storage modulus of the TPU/PP blends increased with the addition of talc, because the talc generated a stiffer interface in the polymer matrix. The comparation results of thermal properties among samples filled with silane treated and untreated talc filler showed that the polymer composites and TPU/PP blends filled with silane treated talc displayed the better thermal properties. The incorporation of fillers into thermoplastics is a fast and cheap method to reduce production costs and modify the mechanical properties. Properties of fillers play an important role in final properties of filler reinforced composites and polymer blends. Chemical properties of fillers are not varied during the melt extrusion processes, but physical characteristics such as filler shape, sizes and size distribution can be change. The filler size and distribution are very important in determining the mechanical properties (stiffness and strength) of composites. Fillers with higher surface areas will contribute to more surface contact between the filler and matrix, thus increasing the mechanical properties of the composite. Fillers with fine or small particles have higher surface areas than fillers with big particles. However, the finer the particles are, the greater their tendency is to agglomerate [1,2] and this can cause an adverse effect on mechanical properties, especially the impact resistance of composites. The reinforcement of elastomers by particulate fillers depended on the physical interactions between the filler and rubber matrix, which can determine the degree of adhesion at interface . The surface modification of fillers by coupling agents results in an improvement of the filler-matrix interaction and provides considerable improvement in the interfacial and mechanical properties of polymer composites. Silane coupling agents have the ability to form a durable bond between organic and inorganic materials. Silane coupling agents have a general formula of R-(CH 2 ) n Si(X) 3 , where R group is a nonhydrolyzable