surface Enrichment in Polymer Blends: Simple Theory and an Experimental Test

1989 ◽  
Vol 154 ◽  
Author(s):  
R.A.L. Jones ◽  
E.J. Kramer ◽  
M.H. Rafailovich ◽  
J. Sokolov ◽  
S.A. Schwarz
Keyword(s):  
Friction And Wear ◽  
Surface Segregation ◽  
Phase Region ◽  
Polymer Mixture ◽  
Recent Theory ◽  
Polymer Mixtures ◽  
Surgical Implants ◽  
Polymeric Solid ◽  
Interface Segregation ◽  
Strength Of Adhesive Joints

AbstractIf a polymer mixture which is in the bulk one-phase region is next to an interface - this may be with another polymer, with a non-polymeric solid, or with the air - the composition of the mixture at the interface will be different from the bulk [1–4]. There are two questions we would like to understand: what determines the composition of the mixture at the interface, and how does that composition increment decay back to the bulk value. This surface or interface segregation has important practical consequences; in the surface case such segregation will profoundly affect wettability, with consequences for the strength of adhesive joints and the biocompatibility of polymeric surgical implants, as well as influencing friction and wear; at interfaces with non-polymers segregation is important for the adhesion of mixed polymer phases to non-polymer phases such as reinforcing fibres or fillers. In this paper we describe some experiments on surface segregation in a very well characterised model system and we describe a recent theory that can be quantitatively tested by our data. We will consider the consequences of this new understanding of surface segregation in polymer mixtures, and we will argue that many of these conclusions may be carried over to the more general case of interface segregation, which opens up a number of interesting technological possibilities.

Surface Enrichment in Polymer Blends: Simple Theory and an Experimental Test

1989 ◽  
Vol 153 ◽  
Author(s):  
R.A.L. Jones ◽  
E.J. Kramer ◽  
M.H. Rafailovich ◽  
J. Sokolov ◽  
S.A. Schwarz
Keyword(s):  
Friction And Wear ◽  
Surface Segregation ◽  
Phase Region ◽  
Polymer Mixture ◽  
Recent Theory ◽  
Polymer Mixtures ◽  
Surgical Implants ◽  
Polymeric Solid ◽  
Interface Segregation ◽  
Strength Of Adhesive Joints

If a polymer mixture which is in the bulk one-phase region is next to an interface - this may be with another polymer, with a non-polymeric solid, or with the air - the composition of the mixture at the interface will be different from the bulk [1-4]. There are two questions we would like to understand: what determines the composition of the mixture at the interface, and how does that composition increment decay back to the bulk value. This surface or interface segregation has important practical consequences; in the surface case such segregation will profoundly affect wettability, with consequences for the strength of adhesive joints and the biocompatibility of polymeric surgical implants, as well as influencing friction and wear; at interfaces with non-polymers segregation is important for the adhesion of mixed polymer phases to non-polymer phases such as reinforcing fibres or fillers. In this paper we describe some experiments on surface segregation in a very well characterised model system and we describe a recent theory that can be quantitatively tested by our data. We will consider the consequences of this new understanding of surface segregation in polymer mixtures, and we will argue that many of these conclusions may be carried over to the more general case of interface segregation, which opens up a number of interesting technological possibilities.

Specific volume and features of compressibility during the molding of powder-polymer mixtures with wax-polypropylene binder

2019 ◽  
pp. 25-33
Author(s):  
Alexander Muranov ◽  
Alexey Semenov ◽  
Anatoly Kutsbakh ◽  
Boris Semenov
Keyword(s):  
Phase Transition ◽  
Comparative Analysis ◽  
Powder Metallurgy ◽  
Injection Molding ◽  
Polymer Binder ◽  
Polymer Mixture ◽  
Powder Injection ◽  
Polymer Mixtures ◽  
Pvt Data ◽  
Mathematical Processing

The article discusses one of the modern areas of powder metallurgy – the technology of manufacturing shaped parts by the powder injection molding (PIM). For the powder-polymer mixture (feedstock) with a wax-polypropylene binder of the solvent-thermal type of removal by isobaric volume dilatometry, the dependence of PVT state parameters was studied. For each component of the polymer binder, the dependence of pressure on the temperature of phase transition was obtained. As a result of mathematical processing and analysis of PVT data for the feedstock of the studied type, a technological window of parameters has been determined that allows injection molding of «green parts» with minimal volume shrinkage. The results of a comparative analysis of the compaction of feedstock with a polymer binder catalytic and solution-thermal type of removal are presented.

scholarly journals Gelation Impairs Phase Separation and Small Molecule Migration in Polymer Mixtures

Polymers ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 1576
Author(s):  
Biswaroop Mukherjee ◽  
Buddhapriya Chakrabarti
Keyword(s):  
Phase Separation ◽  
Rational Design ◽  
Surface Segregation ◽  
Multiscale Methods ◽  
Coarse Grained ◽  
Polymer Gel ◽  
Polymer Mixtures ◽  
Separation Processes ◽  
Surface Migration ◽  
Wide Range

Surface segregation of the low molecular weight component of a polymeric mixture is a ubiquitous phenomenon that leads to degradation of industrial formulations. We report a simultaneous phase separation and surface migration phenomena in oligomer–polymer ( O P ) and oligomer–gel ( O G ) systems following a temperature quench that induces demixing of components. We compute equilibrium and time varying migrant (oligomer) density profiles and wetting layer thickness in these systems using coarse grained molecular dynamics (CGMD) and mesoscale hydrodynamics (MH) simulations. Such multiscale methods quantitatively describe the phenomena over a wide range of length and time scales. We show that surface migration in gel–oligomer systems is significantly reduced on account of network elasticity. Furthermore, the phase separation processes are significantly slowed in gels leading to the modification of the well known Lifshitz–Slyozov–Wagner (LSW) law ℓ ( τ ) ∼ τ 1 / 3 . Our work allows for rational design of polymer/gel–oligomer mixtures with predictable surface segregation characteristics that can be compared against experiments.

Surface Segregation and Wetting from Polymer Mixtures

1994 ◽  
pp. 313-322 ◽  
Author(s):  
Ullrich Steiner ◽  
Erika Eiser ◽  
Andrzej Budkowski ◽  
Lewis Fetters ◽  
Jacob Klein
Keyword(s):  
Surface Segregation ◽  
Polymer Mixtures

Surface segregation in the minority component of the binary polymer mixture

Vacuum ◽  
1999 ◽  
Vol 54 (1-4) ◽  
pp. 273-277 ◽  
Author(s):  
A. Budkowski ◽  
J. Rysz ◽  
F. Scheffold ◽  
J. Klein ◽  
A. Bernasik ◽  
...  
Keyword(s):  
Surface Segregation ◽  
Polymer Mixture ◽  
Binary Polymer

scholarly journals Antibacterial Activity of Tannic Acid and Tannic Acid/Amphiphilic Cationic Polymer Mixtures

2020 ◽  
Vol 32 (6) ◽  
pp. 1491-1496
Author(s):  
Fatimah M. Alzahrani ◽  
Stephen G. Yeates ◽  
Michelle Webb ◽  
Hind Ali Alghamdi
Keyword(s):  
Antibacterial Activity ◽  
Tannic Acid ◽  
Cationic Polymer ◽  
Polymer Mixture ◽  
Klebsiella Pneumonia ◽  
Cationic Polymers ◽  
Polymer Mixtures ◽  
Bacterial Strains ◽  
Gram Positive ◽  
E Coli

In this study, the antibacterial activity of tannic acid/amphiphilic cationic polymer (poly{2-[(methacryloyloxy)ethyl]trimethyl-ammonium chloride}, PMADQUAT) and tannic acid mixtures was examined on the strains of Gram-positive (S. aureus) and Gram-negative (E. coli CI2, E. coli K12, Klebsiella pneumonia and P. aeruginosa) bacteria. Tannic acid exhibited the antibacterial activity against all the studied bacterial strains. The ester linkage between glucose and gallic acid is vital for the antimicrobial activity of tannic acid. Tannic acid inhibited the growth of S. aureus and E. coli K12 (1 wt%) and reduced the growth of P. aeruginosa to 23%. Mixing cationic polymers having different structures (statistical copolymer, homopolymer and diblock polymer) with tannic acid lead to an increase in antibacterial activity of tannic acid and the stability and clarity of mixtures was higher than that of a pure tannic acid solution. Tannic acid/diblock polymer and tannic acid/homopolymer mixtures (0.1 wt%) were excellent for inhibiting the growth of planktonic E. coli K12 bacteria, and a low concentration (0.0001 wt%) of tannic acid/diblock polymer reduced its growth to 19%. By contrast, the tannic acid/statistical polymer mixture (0.0001 wt%) was excellent for inhibiting the growth of Gram-positive S. aureus bacteria.

Apparent phase dissolution at the two-phase region in polymer-polymer mixtures

Polymer ◽  
1989 ◽  
Vol 30 (10) ◽  
pp. 1845-1850 ◽  
Author(s):  
Takashi Ohnaga ◽  
Junko Maruta ◽  
Takashi Inoue
Keyword(s):  
Phase Region ◽  
Polymer Mixtures ◽  
Two Phase ◽  
Phase Dissolution

Ionic polymers based on quaternized polysulfones: hydrodynamic properties of polymer mixtures in solution

2014 ◽  
Vol 86 (11) ◽  
pp. 1871-1882 ◽  
Author(s):  
Anca Filimon ◽  
Adina Maria Dobos ◽  
Ecaterina Avram ◽  
Silvia Ioan
Keyword(s):  
Conformational Changes ◽  
Electrostatic Interactions ◽  
Polymer Composition ◽  
Polymer Mixture ◽  
Solvent Mixtures ◽  
Polymer Mixtures ◽  
Hydrodynamic Properties ◽  
Structural Peculiarity ◽  
Ternary Polymer ◽  
Polymer Solvent

Abstract Hydrodynamic properties developed in a series of mixtures, obtained from quaternized polysulfone and cellulose acetate phthalate or polyvinyl alcohol in N-methyl-2-pyrrolidone, were evaluated by viscometric investigations. Theoretical and experimental aspects concerning the viscometric data for binary polymer/solvent and ternary polymer/polymer/solvent mixtures have been discussed by the new Wolf model, as a function of the charge density of polyion, structural peculiarity of polymers, and polymer mixture composition. Intrinsic viscosity and also the hydrodynamic parameters obtained by the Wolf method offer new information on the competition between different types of interactions manifested in ternary polymer/polymer/solvent systems. The complex dependence of viscosity on polymer composition is influenced by conformational changes of constituent polymers from the mixture, as well as by cumulative effects of electrostatic interactions, hydrogen bonding or association phenomena. Additionally, the above-mentioned interactions indicate the compatibility of these polymers over a large composition domain. This study investigates the hydrodynamic functions from the perspective of some newly-issued theories and analyzes the choice of optimal polymer mixtures compositions for specific applications in biomedical domains.

Polymer Mixtures as Colon Targeted Drug Delivery Systems

2013 ◽  
Vol 690-693 ◽  
pp. 2131-2136
Author(s):  
Mario Helmis ◽  
Mont Kumpugdee-Vollrath
Keyword(s):  
Local Treatment ◽  
Delivery Systems ◽  
Water Soluble ◽  
Polymer Mixture ◽  
Small Scale ◽  
Polymer Mixtures ◽  
Release Studies ◽  
Water Soluble Drugs ◽  
Model Drug ◽  
Colon Diseases

For the development of colon delivery systems (CDS) formulations have to be gastric resistant. The advantage of the CDS is the ability for a local treatment for colon diseases but also its systemic action. CDS can also increase the bioavailability of poorly water soluble drugs e.g. resveratrol, which can be degraded in the upper gastrointestinal tract or by the First-Pass-Effect. In this project the coating technique with different polymer mixtures containing Kollicoat MAE-30DP, Eudragit-NM, Eudragit-L, and Eudragit-NE was investigated. Resveratrol was used as a model drug and all formulations were coated with a polymer mixture in a small scale fluidized bed apparatus. Morphology, roughness and film thickness of the coated tablets were determined by a scanning electron microscope and a 3D light microscope. Drug amount was determined by UV-spectrometry. Release studies were performed in a dissolution apparatus type II. Kinetic profiles of drug release were demonstrated. Results exhibit the advantages of polymer mixtures for CDS in comparison with results of pure Kollicoat MAE-30DP which were published in one of our latest publications.

Characterizing Polymer Surfaces and Interfaces

MRS Bulletin ◽  
1996 ◽  
Vol 21 (1) ◽  
pp. 49-53 ◽  
Author(s):  
T.R Russell
Keyword(s):  
Spatial Distribution ◽  
Polymer Chain ◽  
Diblock Copolymers ◽  
Surface Effects ◽  
Polymer Chains ◽  
Solid Polymer ◽  
Polymer Mixture ◽  
Interface Plane ◽  
Polymer Mixtures ◽  
Polymer Molecules

The presence of a surface or interface can markedly alter the configuration and spatial distribution of polymer molecules. In the bulk, polymer molecules—comprised of numerous monomers covalently linked together—pervade 10s of nanometers spatially. However, packing such chains at an interface—under the constraint that a solid polymer is essentially incompressible—necessitates perturbations to the chain configurations near the interface. This may result in a collapse of coils at the surface or in a preferential orientation of the monomers with respect to the interface plane. For amorphous homopolymers, however, simulations indicate that, on a segmental level, surface effects are generally damped within several segment diameters from the surface. Interactions between the surface and the polymer chains place additional constraints on the molecular configurations. As the architecture of the polymer chain becomes more complex, as with diblock copolymers in which two chemically distinct polymer chains covalently bond together at one end, the packing of chains at the interface must take into account the relative interactions of the two portions of the chains with the interface. Due to the connectivity of the blocks, preferential interactions of the blocks with the interface can influence the spatial distribution of the chains far from the interface. As the number of components increases, as with a simple binary-polymer mixture, not only must packing constraints be satisfied, but also the interactions of the two chains with the surface and with each other must be taken into account. In the case of homogeneous mixtures, the preferential interaction of one chain with an interface can lead to a substantial excess of that chain at the interface which, depending upon the proximity to the demixing point, can lead to surface effects that propagate many molecular diameters into the sample. The key, however, is the connectivity of the monomers in the polymer chain, which can enhance surface effects, as in the case of block copolymers or polymer mixtures, or suppress surface effects, as in the case of homopolymers.

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