Mechanical behaviour of polymer mixtures in the phase separation region

1995 ◽  
Vol 73 (11) ◽  
pp. 1966-1971 ◽  
Author(s):  
V.N. Kuleznev ◽  
L.B. Kandyrin
Keyword(s):  
Phase Separation ◽  
Mechanical Characteristics ◽  
Narrow Range ◽  
Complex Viscosity ◽  
Polymer Mixture ◽  
Polymer Mixtures ◽  
Dynamic Moduli ◽  
Sharp Minimum ◽  
Critical Opalescence ◽  
The Moment

The liquid–liquid phase transition triggered by changes in the composition of polymer mixtures in solution or melt is often accompanied by "critical" opalescence, which signals the appearance of a microemulsion in the mixture. The viscosity of the polymer mixture in this region is characterized by a sharp minimum, observed, as a rule, over an extremely narrow range of concentration. Depending on the concentration of the solution, the type of polymer, and the solvent, the viscosity may decrease by a factor of 8–10. On transition from micro- to macro-separation, viscosity rapidly increases back to the original level. Changes in the composition of the mixture can alter the concentration at which phase separation occurs, but the minimum in viscosity invariably corresponds to the moment of phase separation. The critical opalescence region represents the formation of phase particles up to 80–100 nm in size, and this corresponds to the point of viscosity drop. This effect is due to the appearance of thermodynamically stable microemulsions in the polymer mixture, in the region between the binodal and the spinodal in the phase diagram. These emulsions are characterized by lower molecular interaction of incompatible polymers in the highly developed interfacial layer. Extremal changes at the point of phase separation are also observed for other mechanical characteristics of polymer mixtures in solutions or melts, for example, G′ and G″ dynamic moduli or complex viscosity η*. Keywords: polyblends, critical phenomena, viscosity, emulsions, phase separation.

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.

SIMULATION OF DOOR MOVEMENT WITH A CLOSING MECHANISM

2021 ◽  
Vol 2021 (11) ◽  
pp. 4-10
Author(s):  
Aleksandr Reutov
Keyword(s):  
Mechanical Characteristics ◽  
Dynamic Models ◽  
Quality Criteria ◽  
Strong Impact ◽  
Closing Time ◽  
Door Opening ◽  
Air Resistance ◽  
The Moment ◽  
Moment Of Resistance ◽  
Closing Mechanism

The work objective is to determine the parameters of the closing mechanism that provide the specified characteristics of the door movement. Research method: computer simulation of the movement of a door with a lock mechanism as a multi-mass dynamic system, taking into account the mechanical characteristics and contact interaction of the lock mechanism. Research results and novelty. Computer dynamic models of a door with a door closer and a door with a spring have been developed. The moments of the door opening force, the closing time of the door, the angular velocity of the door at the time of impact with the frame are considered as the criteria for the quality of the door closing mechanism. Formulas are obtained that determine the permissible values of stiffness and deformation of the door closer spring according to the specified moments of the door opening force. The movement of doors with a door closer and with a spring is compared. The parameters of the closing mechanism providing the specified characteristics of the door movement of the considered example are determined. It is shown that with the same values of the opening force moments, the speed of impact with the frame in the case of the door closer is less than the door with a spring. Conclusions: The developed computer dynamic models of a door with a door closer and a door with a spring make it possible to determine the characteristics of the door movement taking into account the inertial and mechanical characteristics of the door closer and spring mechanisms. The permissible values of stiffness and deformation of the door closer spring can be determined by the specified moments of the door opening force in two positions. It is established that the forces of air resistance and friction in the hinges of the door cannot create the moment of resistance necessary for smooth closing of the door without a strong impact on the frame with a limited closing time. The quality criteria that minimize the closing time and the speed of impact of the door with the frame are contradictory. The choice of optimal parameters of the door closing mechanism is possible if one of the criteria is replaced by a restriction. The developed formulas and computer models are recommended for use in the design of devices that restrict the movement of doors.

Characterization of a Composite Material Consisting of a Polyester Resin Matrix with Reinforcement of Horsemane in Flat Tissue

2020 ◽  
Vol 995 ◽  
pp. 49-55
Author(s):  
Christian G Bautista ◽  
Patricio I. Mena ◽  
Cristian A. Paredes ◽  
Marco Antonio Paredes
Keyword(s):  
Mechanical Characteristics ◽  
Sheet Steel ◽  
Resin Matrix ◽  
Matrix Resin ◽  
Biodegradable Composites ◽  
Test Pieces ◽  
Polyester Matrix ◽  
The Moment ◽  
Made In

The manufacture of mechanical components by means of biodegradable composites is the best alternative at the moment of reducing cost and weight, maintaining the mechanical characteristics. In this work the mechanical characteristics are shown as the result of combining a polyester matrix resin with a reinforcement of animal fiber such as horsehair. The results obtained correspond to mechanical characterization tests at traction, bending and impact by dart drop according to rules ASTM D3039/D3039M-17, D7264/D7264M-15 and D5628 respectively, made in four groups of test pieces of material combining a polyester matrix resin and reinforcement of horsemane. The development of materials composed of horsehair as reinforcements offers similar mechanical characteristics with traditional materials such as sheet steel or polymers, but with a considerable weight reduction, ideal for automotive applications such as bodywork or interior parts of vehicles.

Two-step phase separation of a polymer mixture. I. New scaling analysis for the main scattering peak

2000 ◽  
Vol 112 (15) ◽  
pp. 6886-6896 ◽  
Author(s):  
Takeji Hashimoto ◽  
Masaki Hayashi ◽  
Hiroshi Jinnai
Keyword(s):  
Phase Separation ◽  
Polymer Mixture ◽  
Scaling Analysis

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.

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.

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