Mixing Of Polymers Research Articles

Preparation and Characterization of Newly Developed Polysulfone/Polyethersulfone Blend Membrane for CO<sub>2</sub> Separation

Polymeric membranes suffer from so called upper bound tradeoff between permeability and selectivity as described by Robeson. Polymer blending is a valuable technique to tune the properties of polymeric membranes by physical mixing of different polymers in a single mixture. In this study, preparation and characterization of newly developed polysulfone/polyethersulfone (PSF/PES) blend flat sheet dense membranes is described for CO2/CH4 separation. Blend membranes with different blending ratios were prepared and the developed membranes were characterized by FESEM, FTIR and TGA to see the effect of blend ratio on morphology, bonding and thermal stability respectively. Permeability of CO2 and CH4 gases in pressure range of 2-10 bar is recorded to find out the ideal selectivity of prepared membranes. The results are discussed and compared with individual polymer membranes.

Magnetic Properties of Fe@FeSiAl Oxide Nanoparticles and Magneto-Dielectric Properties of Their Composite Sheets

Macroscopically core-shell structured Fe@FeSiAl oxide nanoparticles and their composite sheets were manufactured through a series of simple procedures such as solution combustion synthesis, hydrogen reduction, mixing of polymer and filler, and hot pressing of stacked tape cast films. To evaluate the high frequency magnetic properties of the Fe composite nanopowders, metallic element composition (Fe:Si:Al), hydrogen reduction temperature were controlled and then analyzed using Landau-Lipschitz-Gilbert equation and extended EMT mixing rule. The magneto-dielectric properties of the composite sheet containing 75 wt% 95:3:2 in Fe:Si:Al content powder were a permittivity of 2.5 with a dielectric loss of <;1% and a permeability of 2.0 with a magnetic loss of <;15% at 1 GHz. This result showed that the bandwidth of a patch antenna with the composite sheet substrate could be improved by 4.9 times wider compared with that of a patch antenna with Co2Y type hexagonal Ba ferrite substrate. Furthermore, the composite sheet has a good mechanical flexibility, which leads to a conformal structure. Thus, the composite sheet can be a good candidate for antenna substrate of mobile handsets.

Spectroscopic Evaluation of Mixing and Crystallinity of Fullerenes in Bulk Heterojunctions

The microstructure of blend films of conjugated polymer and fullerene, especially the degree of mixing and crystallization, impacts the performance of organic photovoltaic devices considerably. Mixing and crystallization affect device performance in different ways. These phenomena are not easy to screen using traditional methods such as imaging. In this paper, the amorphous regiorandom poly(3-hexylthiophene) is blended with the potentially crystalline fullerene [6,6]-phenyl-C61-butyric acid methyl ester PCBM and the amorphous bis-adduct. First, the degree of mixing of polymer: fullerene blends is evaluated using UV–Vis absorption, steady-state and ultra-fast photoluminescence spectroscopy. The blue-shift of the polymer emission and absorption onset are used in combination with the saturation of the polymer emission decay time upon fullerene addition in order to infer the onset of aggregation of the blends. Second, the crystallinity of the fullerene is probed using variable angle spectroscopic ellipsometry (VASE), electroluminescence and photoluminescence spectroscopy. It is shown that the red-shift of charge transfer emission in the case of PCBM based blends cannot be explained solely by a variation of optical dielectric constant as probed by VASE. A combination of optical spectroscopy techniques, therefore, allows to probe the degree of mixing and can also distinguish between aggregation and crystallization of fullerenes.

A Molecular Thermodynamic Model for Restricted Swelling Behaviors of Thermo-sensitive Hydrogel

A molecular thermodynamic model was developed for describing the restricted swelling behavior of a thermo-sensitive hydrogel confined in a limited space. The Gibbs free energy includes two contributions, the contribution of mixing of polymer and solvent calculated by using the lattice model of random polymer solution, and the contribution due to the elasticity of polymer network. This model can accurately describe the swelling behavior of restricted hydrogels under uniaxial and biaxial constraints by using two model parameters. One is the interaction energy parameter between polymer network and solvent, and the other is the size parameter depending on the degree of cross-linking. The calculated results show that the swelling ratio reduces significantly and the phase transition temperature decreases slightly as the restricted degree increases, which agree well with the experimental data.

The introductory evaluation of possibility of using waste perlite powder in building polymer composites

The paper deals with possibility of use of waste perlite powder as a microfiller in the building polymer composites. The perlite powder influences the technological properties of the polymer mixes, while the mechanical properties of the hardened composite are not significantly affected. The obtained results confirm the possibility of rational use of the waste material, which is in agreement with the rules of the sustainable development in construction. Till now, 5 % (by mass) of conventional microfiller in the polyester composite have been successfully substituted by perlite powder, which means the utilization of large amounts of this waste, due to its low bulk density (&lt; 100 kg/m3). The authors will attempt to increase the degree of substitution. However, it will require resolving some technological problems involved particularly with the deterioration of the polymer mixes workability by the addition of the perlite powder.

Mixing and segregation of ring polymers: spatial confinement and molecular crowding effects

During the life cycle of bacterial cells the non-mixing of the two ring-shaped daughter genomes is an important prerequisite for the cell division process. Mimicking the environments inside highly crowded biological cells, we study the dynamics and statistical behavior of two flexible ring polymers in the presence of cylindrical confinement and crowding molecules. From extensive computer simulations we determine the degree of ring-ring overlap and the number of inter-monomer contacts for varying volume fractions ϕ of crowders. We also examine the entropic demixing of polymer rings in the presence of mobile crowders and determine the characteristic times of the internal polymer dynamics. Effects of the ring length on ring-ring overlap are also analyzed. In particular, on systematic variation of the fraction of crowding molecules, a -scaling is found for the ring-ring overlap length along the cylinder axis, and a non-monotonic dependence of the 3D ring-ring contact number with a maximum at is obtained. Our results demonstrate that polymer rings are demixed and separated by particular entropy-favourable partitioning of crowders along the axis of the cylindrical simulation box. These findings help to rationalize the implications of macromolecular crowding for circular DNA molecules in confined spaces inside bacteria as well as in localized cellular compartments inside eukaryotic cells.

Designing Hybrid Inorganic-Organic Materials By Utilizing Sol-Gel Chemistry for Batteries and Energy Storage

The focus of this work is to investigate the morphology, physical properties, and ion transport of tetraethyl orthosilicate (TEOS)-titanium isopropoxide (TIP)-polymer hybrid membranes depending on different composition. TEOS and TIP are two precursors used in sol-gel process to prepare Si-Ti mixed materials as the inorganic component. Penta block copolymer (PBC) is used as the organic component, which is poly(t-butyl styrene-b-ethylene-co-propylene-b-styrene-co-styrenesulfonate-b-ethylene-co-propylene-b-t-butyl styrene). Unlike the previous work done by soaking membrane in inorganic sol or mixing polymer with inorganic particles, TEOS-TIP-PBC hybrid membranes were prepared from homogenous inorganic-organic solutions by controlling different TEOS: TIP molar ratio and different concentration of inorganic components in hybrid membranes. Contact angle data by Kruss DSA 100 surface analyser, water uptake, proton conductivity by Autolab potentiostat, mechanical properties by dynamic mechanical analysis (DMA), and thermal stability by thermal gravity analysis (TGA) were investigated and highly affected by the composition. The most interesting results we found is that the proton conductivity of hybrid membranes with both acid and salt form was significantly increased compared with the pure PBC membranes, which opens the potential that these novel hybrid materials can be used in fuel cells, lithium-ion battery, or vanadium redox flow battery. In the future work, other polymers with sulfonate group, such as Nafion, will be included to prepare hybrid membranes. Moreover, other characterizations and applications, such as transmission electron microscopy (TEM), small angle x-ray scattering (SAXS), methanol permeability, and single cell performance of these hybrid membranes will be further investigated.

TEOS-TIP-PBC Hybrid Inorganic-Organic Membranes for Batteries and Energy Storage

The focus of this work is to investigate the morphology, physical properties, and ion transport of Tetraethyl orthosilicate (TEOS)-Titanium isopropoxide (TIP)-Penta block copolymer (PBC) hybrid membranes depending on different composition. TEOS and TIP are two precursors used in sol-gel process to prepare Si-Ti mixed materials as the inorganic component. PBC is poly(t-butyl styrene-b-ethylene-co-propylene-b-styrene-co-styrenesulfonate-b-ethylene-co-propylene-b-t-butyl styrene) as the organic component. Unlike the previous work done by soaking membrane in inorganic sol or mixing polymer with inorganic particles, TEOS-TIP-PBC hybrid membranes were prepared from homogenous inorganic-organic solutions by controlling different TEOS: TIP molar ratio and different concentration of inorganic components in hybrid materials. Contact angle data by Kruss DSA 100 surface analyser, water uptake, proton conductivity by Autolab potentiostat, mechanical properties by dynamic mechanical analysis (DMA), and thermal stability by thermal gravity analysis (TGA) were investigated and highly affected by the composition. The most interesting results we found is that the proton conductivity of hybrid membranes with both acid and salt form was significantly increased compared with the pure PBC membranes, which opens the potential that these novel hybrid materials can be used in fuel cells, lithium-ion battery, or vanadium redox flow battery. In the future work, other polymers with sulfonate groups, such as Nafion, will be included to prepare hybrid membranes. Moreover, other characterizations and applications, such as transmission electron microscopy (TEM), small angle x-ray scattering (SAXS), methanol permeability, and single cell performance of these hybrid membranes will be further investigated.

Polymer Vesicles Formed by Mixing of Amphiphilic Polymer and Hydrophobic Cholesterol-containing Homopolymer in Water

Polymer Vesicles Formed by Mixing of Amphiphilic Polymer and Hydrophobic Cholesterol-containing Homopolymer in Water

Charge generation and transport in efficient organic bulk heterojunction solar cells with a perylene acceptor

The origin of high current density in efficient non-fullerene based bulk heterojunction (BHJ) organic solar cells employing a non-planar perylene dimer (TP) as an electron acceptor and a thiophene based donor polymer PBDTTT-CT is investigated using electrical and optical techniques. Photoluminescence measurements reveal almost complete quenching of both the donor and acceptor excitons, indicating efficient electron and hole transfer processes. The nanomorphology of the films shows fine mixing of the donor polymer and TP at 50 : 50% weight ratio with a photon to current conversion efficiency (IPCE) of 45% in the visible regime. At the donor–acceptor interface, both polymer and TP excitons undergo fast dissociation with similar time scales of a few picoseconds. The magnitude of the polaron yield of PBDTTT-CT:TP blends is observed to be comparable to that of PBDTTT-CT:PC70BM blends and exhibits similar μs-decay dynamics. A power conversion efficiency of 3.2% is achieved for devices with 50 : 50% by weight compositional ratio of polymer and TP.

Comparison of Antibacterial Properties of Nano TiO2and ZnO Particle Filled Polymers

Antibacterial property for the plastic products is very important due to their wide spread usage in many areas close to human health such as a child toy or a food package. There are some methods to make polymers antibacterial such as ionizing radiation but they can be still infected by micro organisms during usage of them. The best and easy way to obtain antibacterial polymers is melt mixing of polymers with antibacterial agents. In this study, nano TiO2 and ZnO particles were mixed with polypropylene and high density polyethylene with a twin screw extruder. Silane was applied to the particles prior melt mixing in order to prevent agglomeration and FT-IR analysis was done to characterize the particles. After melt mixing, particle lled rectangular plates were obtained by plastic injection molding and antibacterial tests were done on the plates according to a standard method, JIS Z 2801. According to the results, satisfactory antibacterial properties were obtained for both polymers and it has been seen that particles without silane could not provide antibacterial e ect.

Triboelectricity in insulating polymers: evidence for a mechanochemical mechanism.

Transfer of reaction products formed on the surfaces of two mutually rubbed dielectric solids makes an important if not dominating contribution to triboelectricity. New evidence in support of this statement is presented in this report, based on analytical electron microscopy coupled to electrostatic potential mapping techniques. Mechanical action on contacting surface asperities transforms them into hot-spots for free-radical formation, followed by electron transfer producing cationic and anionic polymer fragments, according to their electronegativity. Polymer ions accumulate creating domains with excess charge because they are formed at fracture surfaces of pulled-out asperities. Another factor for charge segregation is the low polymer mixing entropy, following Flory and Huggins. The formation of fractal charge patterns that was previously described is thus the result of polymer fragment fractal scatter on both contacting surfaces. The present results contribute to the explanation of the centuries-old difficulties for understanding the "triboelectric series" and triboelectricity in general, as well as the dissipative nature of friction, and they may lead to better control of friction and its consequences.

Insights into the swelling process and drug release mechanisms from cross-linked pectin/high amylose starch matrices

Cross-linked pectin/high amylose mixtures were evaluated as a new excipient for matrix tablets formulations, since the mixing of polymers and cross-linking reaction represent rational tools to reach materials with modulated and specific properties that meet specific therapeutic needs. Objective: In this work the influence of polymer ratio and cross-linking process on the swelling and the mechanism driving the drug release from swellable matrix tablets prepared with this excipient was investigated. Methods: Cross-linked samples were characterized by their micromeritic properties (size and shape, density, angle of repose and flow rate) and liquid uptake ability. Matrix tablets were evaluated according their physical properties and the drug release rates and mechanisms were also investigated. Results: Cross-linked samples demonstrated size homogeneity and irregular shape, with liquid uptake ability insensible to pH. Cross-linking process of samples allowed the control of drug release rates and the drug release mechanism was influenced by both polymer ratio and cross-linking process. The drug release of samples with minor proportion of pectin was driven by an anomalous transport and the increase of the pectin proportion contributed to the erosion of the matrix. Conclusion: The cross-linked mixtures of high amylose and pectin showed a suitable excipient for slowing the drug release rates.

Design on the Polymer Temperature Control System for Tandem Mixer

s: Polymer mixing is the key process of rubber products manufacturing, and mixer is the core equipment in polymer mixing process. By analysis of the effective factors on mixer mixing temperature, this paper study realization method of temperature control system. A polymer temperature control system using tandem mixing technology is designed to improve the mixing efficiency and the quality.

Nanoprecipitation of polymers in a bad solvent

Nanoparticles (NPs) composed of polymers are of great interest since they can add a functionality in many applications, ranging from food and pharma to plastics and electronics. A key factor that determines the functionality of NPs is their size. Nanoprecipitation [1] is a commonly used technique to prepare NPs. We have performed a combined experimental and theoretical study on the size of NPs formed by precipitation of polymers into a bad solvent in the presence of a stabilizing surfactant.We propose an extension of the theoretical framework put forward by Lannibois et al. [10] for nanoparticle formation via precipitation. Our theory is based upon a kinetic model for diffusion limited coalescence (DLC) in which the relevant transport and diffusion mechanisms are quantified. We find that the macroscopic mixing time and the diffusivity of the polymer and surfactant are the main parameters determining the final particle size. The theoretical result for the final size can be condensed into a single analytical expression. At given polymer concentration and mixing time, it follows that the smallest particles can be obtained in the excess of surfactant. This situation corresponds well to the experimentally used conditions. The mixing efficiency is predicted to have a profound influence on the final particle diameter: faster mixing results in smaller particles. The final particle size in the slow mixing regime, which is the typical situation in experiments, turns out to be independent of the molar mass of the polymer and scales as a power 1/3 with the initial polymer concentration. An increase of the surfactant molar mass is predicted to lead to larger particles, because of longer mixing time and lower surfactant mobility.We have performed systematic experimental investigations on nanoparticles formation using various systems but focused on polycaprolactone (PCL) polymers in acetone precipitated in aqueous solutions containing polyvinyl alcohol as surfactant. The PCL molar mass and concentration and mixing time were varied. We show that both our experimental results as well as literature data are in good agreement with our theoretical DLC predictions. This work therefore provides a solid framework for tailoring nanoparticles with a desired size.

Optimisation of Experimental Techniques to Enhance the Efficiency of Polymer Photovoltaic Cell

The idea of generating electricity from plastics itself sounds enthralling, but it is equally challenging to achieve in the lab and then take it to the production level. Polymer Solar Cells (PSCs) have the advantage of lower cost and flexibility but they do suffer from problems like low efficiency and smaller service life which is mainly due to limited absorption spectra, poor charge mobility and the degradation of the polymers. A combination of narrow band donor and fullerene derivative is one of the possible approaches to fabricate a working device. In this work, various experimental techniques have been optimised in order to achieve better efficiency of the PSCs in atmospheric condition. Optimized parameters from polymer mixing ratio, spin coating, annealing and others were used to enhance efficiency of device. Parameters were optimized with the help various techniques viz. Viscometer, Thermo Gravity Analysis, UV-vis spectroscopy, Scanning Electron Microscopy and I-V measurement system. We report 0.76% efficiency in these solar cells, which were fabricated in open atmospheric condition. The as-prepared device showed a good performance with an open-circuit voltage (Voc) 0.74 V, short circuit current (Isc) 0.6 mA, a fill factor (FF) of 35%.

Study on Polymer-Modified Concrete for Improving Flexural Toughness

This paper studies how polymer alters the flexural toughness of concrete. By selecting five different types of polymer mixing into concrete; results indicate that polymer has obvious effect to enhance toughness of concrete evaluated by toughness index T. Microstructure of polymer-modified concrete were studied through environment scanning electron microscope, digital micro-hardness tester and nanoindentor, results indicate that polymer form the ionic compounds and reduce the crystallization of Ca (OH) 2, acting as a flexible filler and reinforcement in concrete. Polymer also alters the microstructure at the aggregatecement interfacial transition zone.

Evaluation on the Drug–Polymer Mixing Status in Amorphous Solid Dispersions at the Early Stage Formulation and Process Development

Drug and polymer mixing status in amorphous solid dispersions, an important aspect with regard to the physical stability and in vivo performance of such systems, was evaluated in this report with two case studies. In the first case study, the mixing between the drug and the polymer in an amorphous solid dispersion was assessed at both particulate and bulk levels to ensure that a homogeneous solid dispersion was obtained. In the second study, drug–polymer distribution evaluation in amorphous solid dispersions facilitated the selection of an optimal drug loading and a robust manufacturing process at the early stage of formulation development. Through these two case studies, it is suggested that establishing a multi-faceted characterization approach for amorphous solid dispersions is key to achieve a better understanding of these complex systems and successful delivery of stable and efficacious amorphous formulations.

Highly efficient miniaturized coprecipitation screening (MiCoS) for amorphous solid dispersion formulation development

Microprecipitated bulk powder (MBP) is a novel solid dispersion technology to manufacture amorphous formulations of poorly soluble compounds that cannot be processed by spray drying or melt extrusion. An efficient high-throughput screening method has been developed to aid the selection of polymer type, drug loading and antisolvent to solvent ratio for MBP formulation development. With a 96-well platform, the miniaturized coprecipitation screening (MiCoS) includes mixing of drug and polymer in dimethylacetamide, controlled precipitation to generate MBP, filtration/washing, drying and high throughput characterization. The integrated MiCoS approach has been demonstrated with a model compound, glybenclamide. Based on the solid state stability and kinetic solubility of the MBP, hydroxypropylmethylcellulose acetate succinate polymer with 40% or lower drug loading, and antisolvent (0.01 N HCl) to solvent (dimethylacetamide) ratio of 5:1 or higher were selected to make glybenclamide MBP. MiCoS can be applied to both early and late stage formulation processing. In early stage research programs, the system can be used to enable efficacy, pharmacokinetics or mini-toxicology studies for poorly water soluble molecules using minimal amount of drug substance (2-10mg). In late stage development programs, MiCoS can be used to optimize MBP formulation by expanding the experimental design space to include additional formulation variants.

Regular Mixing Thermodynamics of Hydrogenated Styrene–Isoprene Block–Random Copolymers

Random copolymerization of A and B monomers represents a versatile method to tune interaction strengths between polymers, as ArB random copolymers will exhibit a smaller effective Flory interaction parameter χ (or interaction energy density X) upon mixing with A or B homopolymers than upon mixing A and B homopolymers with each other, and the ArB composition can be tuned continuously. This approach can also be used to tune the segregation strength in A–ArB “block–random” copolymers. Simple models of polymer mixing thermodynamics suggest that the effective interaction energy density in such block–random copolymers should follow XA–ArB = fB2XA–B, but this prediction has not been tested quantitatively. The present work systematically assesses the validity of this rule for thermally stable hydrogenated derivatives of styrene–isoprene block copolymers, through measurements of the order–disorder transition (ODT) temperature on near-symmetric diblock and diblock–random copolymers of varying composition and suitab...