Bicontinuous microdomain morphology of block copolymers. 1. Tetrapod-network structure of polystyrene-polyisoprene diblock polymers

1987 ◽  
Vol 20 (7) ◽  
pp. 1651-1662 ◽  
Author(s):  
Hirokazu Hasegawa ◽  
Hideaki Tanaka ◽  
Komei Yamasaki ◽  
Takeji Hashimoto
Keyword(s):  
Block Copolymers ◽  
Network Structure ◽  
Diblock Polymers

Effect of Temperature on Stress-Optical Properties of Styrene Butadiene Block Copolymers

1967 ◽  
Vol 40 (5) ◽  
pp. 1373-1380 ◽  
Author(s):  
E. Fischer ◽  
J. F. Henderson
Keyword(s):  
Optical Properties ◽  
Block Copolymers ◽  
Network Structure ◽  
Effect Of Temperature ◽  
Stress Strain ◽  
Two Phase ◽  
Phase Systems ◽  
Effective Network ◽  
Restricted Mobility ◽  
Styrene Butadiene

Abstract Stress, strain, and optical properties of three elastomeric styrene butadiene block copolymers containing 31, 40 and 49 wt per cent styrene were studied as a function of temperature. Mechanical and optical properties indicate that these materials are two phase systems in which the polybutadiene chains form an elastomeric phase and the polystyrene a glassy phase with the latter providing physical crosslinks. Birefringence measurements indicate that decreases in modulus and strength of these materials are associated with decrease in concentration of elastically effective network chains. Independence of stress-optical coefficient of temperature suggests that the decrease in concentration of elastically effective chains is not due to onset of rubberlike behavior or flow within the polystyrene regions themselves, at least for temperatures below about 70° C. Rather, the decrease seems to be associated with increased mobility of the polybutadiene chains at higher temperatures, which also leads to an increase in the rate of stress relaxation. Birefringence measured during extension and retraction showed that stress strain hysteresis is due to restricted mobility of polybutadiene chain segments rather than to permanent viscous flow or to change in the effective network structure of the block copolymers. The ultimate properties of these rubbers were well correlated with the effective network structure in undeformed specimens.

Alginate-based diblock polymers: Preparation, characterization and Ca-induced self-assembly

2021 ◽  
Author(s):  
Amalie Solberg ◽  
Ingrid Vikøren Mo ◽  
Finn L. Aachmann ◽  
Christophe Schatz ◽  
Bjørn E. Christensen
Keyword(s):  
Block Copolymers ◽  
Renewable Resources ◽  
Self Assembly ◽  
Stimuli Responsive ◽  
Diblock Polymers

Renewable resources can provide a range of different polysaccharide blocks that can be used to prepare new types of stimuli-responsive polysaccharide-based block copolymers. Alginates are natural polysaccharides widely used as...

Rubber-Styrene Block Copolymers in Adhesives

1982 ◽  
Vol 55 (1) ◽  
pp. 208-218 ◽  
Author(s):  
D. J. St. Clair
Keyword(s):  
Block Copolymer ◽  
Block Copolymers ◽  
Network Structure ◽  
High Strength ◽  
Pressure Sensitive Adhesive ◽  
Performance Requirements ◽  
Pressure Sensitive ◽  
Type Form ◽  
Physically Crosslinked ◽  
Rubber Block

Abstract Rubber-styrene block copolymers are materials such as the A-B-A type block copolymers, where A represents a block of polystyrene and B represents a rubber block, usually polybutadiene, polyisoprene or an olefin rubber. Because polymers of this type form a physically crosslinked network structure, the polymers are thermoplastic as well as being strong and rubbery. Because of their unique structure, block copolymers are well suited for use in a wide variety of adhesives. Block copolymers can be formulated with resins, plasticizers, and fillers to meet performance requirements ranging from those of a soft, tacky pressure-sensitive adhesive to those of a stiff, high strength construction or assembly adhesive. Adhesives based on the block copolymers can be mixed and applied, either in solvent or as hot melts, using standard processing equipment. Research is continuing on block copolymer technology, formulating technology, and processing technology which should further expand the applications of block copolymers in adhesives.

An alter-centric perspective on employee innovation: The importance of alters’ creative self-efficacy and network structure.

2017 ◽  
Vol 102 (9) ◽  
pp. 1360-1374 ◽  
Author(s):  
Travis J. Grosser ◽  
Vijaya Venkataramani ◽  
Giuseppe (Joe) Labianca
Keyword(s):  
Network Structure ◽  
Self Efficacy ◽  
Creative Self

Türkiye'de iller arası göçlerin nodexl ile sosyal ağ analizi

2017 ◽  
Vol 4 (1) ◽  
pp. 82-109 ◽  
Author(s):  
Mustafa Yakar ◽  
Fatma Sert Eteman
Keyword(s):  
Network Structure ◽  
Population Data ◽  
Single Mode ◽  
Turkish Population ◽  
Place Of Birth ◽  
Place Of Residence ◽  
Migration Flow ◽  
Population Structures ◽  
The Republic ◽  
Provincial Scale

Türkiye'de 20.yy'ın ortasından itibaren başlayan iç göçler zamanla kurulan göçmen ağları ile süreklilik kazanmış ve ülke içinde nüfusun kır-kent dağılımını değiştirecek boyutlara erişmiştir. Araştırma, göçün doğum yeri verisinden hareketle ikamet edilen yerdeki nüfus miktarına göre alınan ve verilen göç akışının büyüklüğünü iller ölçeğinde yönlü ağlar kullanılarak analiz edilmesini amaçlamaktadır. Araştırmada, TÜİK tarafından yayınlanmış olan 2015 yılına ait, iller ölçeğinde doğum yerine göre ikamet yeri verisi kullanılmıştır. Göçün kaynak ve hedef sahaları arasındaki akışını incelemek için NodeXL ile oluşturulan tek modlu, yönlü ve ağırlıklandırılmış göç ağının istatistiksel olarak tam ağ yapısına sahip olduğu görülmüştür. Ağ grafiklerinden ve istatistiklerinden göç hareketinin doğudan batıya doğru gerçekleştiği ve İstanbul’ un ülkenin tamamına hâkim bir görünüme sahip olduğu anlaşılmaktadır. Türkiye nüfusunun cumhuriyet tarihi içinde geçirdiği iç göç süreçleriyle birlikte ülke içinde kurulmuş ve oldukça karmaşık bir görünüme sahip ağ yapısının olduğu ileri sürülebilir. Kurulan ağlar göçlerin devamını sağladığı gibi, göçün yöneldiği merkezlerde daha heterojen nüfus yapılarının ortaya çıkmasına yol açmıştır.ABSTRACT IN ENGLISHSocial Network Analysis of Migration Inter Provinces In Turkey with Nodexl The internal migrations which started in Turkey in the middle of the 20th century have gained permanency with the migration networks that were established at the time and reached dimensions which have the potential to change the rural-urban distribution of the population within the country.  The study aims to analyze the magnitude of the incoming and outgoing migration flow at the provincial scale based on the population data for place of birth according to place of residence by using directional networks. Place of residence according to place of birth at the provincial scale data for 2015 published by TÜİK was used in the study. A single mode, directional and weighted migration network created with NodeXL to examine the migration flows between the source and target has a statistically complete network structure. The network graphs and statistics show that the migrations have taken place from east to west and Istanbul has a view as dominant of the country. It can be argued that internal network structure of Turkish population has  a very complex view because of internal migration in the history of the republic. The established networks have enabled the continuation of migration and have manifested as the emergence of more heterogeneous population structures in centers where migration had been directed.

Application of Fractal Methods to Ensure the Cyber-Resilience of Self-Organizing Networks

2019 ◽  
Vol 22 (4) ◽  
pp. 336-341
Author(s):  
D. V. Ivanov ◽  
D. A. Moskvin
Keyword(s):  
Information Security ◽  
Network Structure ◽  
Self Regulation ◽  
Security Threats ◽  
Self Organizing Networks ◽  
Self Organizing ◽  
Fractal Methods

In the article the approach and methods of ensuring the security of VANET-networks based on automated counteraction to information security threats through self-regulation of the network structure using the theory of fractal graphs is provided.

Self-Assembly of Hydrogels From Elastin-Mimetic Block Copolymers

2002 ◽  
Vol 724 ◽  
Author(s):  
Elizabeth R. Wright ◽  
R. Andrew McMillan ◽  
Alan Cooper ◽  
Robert P. Apkarian ◽  
Vincent P. Conticello
Keyword(s):  
Block Copolymers ◽  
Self Assembly ◽  
Triblock Copolymers ◽  
Variable Temperature ◽  
Inverse Temperature ◽  
Temperature Transition ◽  
Scanning Calorimetry ◽  
Design Synthesis ◽  
Inverse Temperature Transition ◽  
Functional Biomaterials

AbstractTriblock copolymers have traditionally been synthesized with conventional organic components. However, triblock copolymers could be synthesized by the incorporation of two incompatible protein-based polymers. The polypeptides would differ in their hydrophobicity and confer unique physiochemical properties to the resultant materials. One protein-based polymer, based on a sequence of native elastin, that has been utilized in the synthesis of biomaterials is poly (Valine-Proline-Glycine-ValineGlycine) or poly(VPGVG) [1]. This polypeptide has been shown to have an inverse temperature transition that can be adjusted by non-conservative amino acid substitutions in the fourth position [2]. By combining polypeptide blocks with different inverse temperature transition values due to hydrophobicity differences, we expect to produce amphiphilic polypeptides capable of self-assembly into hydrogels. Our research examines the design, synthesis and characterization of elastin-mimetic block copolymers as functional biomaterials. The methods that are used for the characterization include variable temperature 1D and 2D High-Resolution-NMR, cryo-High Resolutions Scanning Electron Microscopy and Differential Scanning Calorimetry.

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