scholarly journals Hyperbranched Silicone MDTQ Tack Promoters

Molecules ◽  
2019 ◽  
Vol 24 (22) ◽  
pp. 4133 ◽  
Author(s):  
Sijia Zheng ◽  
Shuai Liang ◽  
Yang Chen ◽  
Michael A. Brook
Keyword(s):  
Molecular Weight ◽  
Phase Separation ◽  
Complex Mixtures ◽  
Low Molecular Weight ◽  
Structure Property ◽  
Chain Entanglement ◽  
Silicone Gel ◽  
Structure Property Relationships ◽  
Branch Density

Low molecular weight, highly crosslinked silicone resins are widely used as reinforcing agents for highly transparent elastomers and adhesion/tack promoters in gels. The resins are complex mixtures and their structure / property relationships are ill defined. We report the synthesis of a library of 2, 3 and 4-fold hyperbranched polymeric oils that are comprised of linear, lightly branched or highly branched dendronic structures. Rheological examination of the fluids and tack measurements of gels filled with 10, 25 or 50% dendronic oils were made. Viscosity of the hyperbranched oils themselves was related to molecular weight, but more significantly to branch density. The properties are driven by chain entanglement. When cured into a silicone gel, less densely branched materials were more effective in improving tack than either linear oils or Me3SiO-rich, very highly branched oils of comparable molecular weight, because the latter oils underwent phase separation.

scholarly journals Design Strategy for Self-Healing Epoxy Coatings

Coatings ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 50 ◽  
Author(s):  
Dian Yuan ◽  
Vahab Solouki Bonab ◽  
Ammar Patel ◽  
Talha Yilmaz ◽  
Richard A. Gross ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Phase Separation ◽  
Thermoplastic Polyurethane ◽  
Polymeric Materials ◽  
Secondary Phase ◽  
Diglycidyl Ether ◽  
Self Healing ◽  
Structure Property ◽  
Chain Entanglement ◽  
Epoxy Network

Self-healing strategies including intrinsic and extrinsic self-healing are commonly used for polymeric materials to restore their appearance and properties upon damage. Unlike intrinsic self-healing tactics where recovery is based on reversible chemical or physical bonds, extrinsic self-healing approaches rely on a secondary phase to acquire the self-healing functionality. Understanding the impacts of the secondary phase on both healing performance and matrix properties is important for rational system design. In this work, self-healing coating systems were prepared by blending a bio-based epoxy from diglycidyl ether of diphenolate esters (DGEDP) with thermoplastic polyurethane (TPU) prepolymers. Such systems exhibit polymerization induced phase separation morphology that controls coating mechanical and healing properties. Structure–property analysis indicates that the degree of phase separation is controlled by tuning the TPU prepolymer molecular weight. Increasing the TPU prepolymer molecular weight results in a highly phase separated morphology that is preferable for mechanical performances but undesirable for healing functionality. In this case, diffusion of TPU prepolymers during healing is restricted by the epoxy network rigidity and chain entanglement. Low molecular weight TPU prepolymers tend to phase mix with the epoxy matrix during curing, resulting in the formation of a flexible epoxy network that benefits TPU flow while decreasing Tg and mechanical properties. This work describes a rational strategy to develop self-healing coatings with controlled morphology to extend their functions and tailor their properties for specific applications.

SYNTHESIS AND CHARACTERIZATION OF FARNESENE-BASED POLYMERS

2017 ◽  
Vol 90 (2) ◽  
pp. 308-324 ◽  
Author(s):  
Taejun Yoo ◽  
Steven K. Henning
Keyword(s):  
Molecular Weight ◽  
Anionic Polymerization ◽  
Molar Mass ◽  
Functional Materials ◽  
Synthesis And Characterization ◽  
Low Molecular Weight ◽  
Structure Property ◽  
Structure Property Relationships ◽  
By Products

ABSTRACT A bio-based route to the production of trans-β-farnesene has recently been commercialized. Trans-β-farnesene is capable of being polymerized by both anionic and cationic pathways, creating low molecular weight polymers with structure–property relationships unique within the diene class of monomers. Trans-β-farnesene is produced through fermentation of sugar feedstocks. The pathway offers an alternative to petroleum-based feedstocks derived as by-products of naphtha or ethane cracking. Anionic polymerization of the monomer produces a highly branched “bottlebrush” structure, with rheological properties that are markedly different than those of linear diene polymers. Specifically, a lack of entanglements is observed even at relatively high molar masses. For hydroxyl-terminated oligomers, Tg as a function of molar mass follows a trend opposite non-functional materials. The synthesis and characterization of trans-β-farnesene–based polymers will be presented, including anionically prepared low molecular weight diols and monols.

Crosslinking and Mechanical Properties of Liquid Rubber. I. Curative Effect of Aliphatic DIOLS

1979 ◽  
Vol 52 (5) ◽  
pp. 920-948 ◽  
Author(s):  
Yuji Minoura ◽  
Shinzo Yamashita ◽  
Hiroshi Okamoto ◽  
Tadao Matsuo ◽  
Michiaki Izawa ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Molecular Weight ◽  
Low Molecular Weight ◽  
Structure Property ◽  
X Ray Diffraction ◽  
Curative Effect ◽  
Polyurethane Elastomers ◽  
X Ray ◽  
Structure Property Relationships ◽  
The Difference

Abstract The structure-property relationships of polyurethane elastomers derived from a liquid hydroxyl-terminated polybutadiene/low molecular weight aliphatic diol/diisocyanate system were studied. The effects of the amount of low molecular weight diol on the mechanical properties of the elastomer were discussed on the basis of the results of stress-strain, swelling, dynamic viscoelasticity, x-ray diffraction, etc. It was found that some particular combinations of low molecular weight diol and diisocyanate specifically affect the properties of elastomers. When the mechanical properties of the elastomers were plotted against the number of methylene carbons in the low molecular weight diol, characteristic zigzag patterns were obtained. These patterns were explained by the difference in the packing and the dependence of the strength of intermolecular hydrogen bonding on whether the number of the methylene carbons was even or odd. This assumption was confirmed by x-ray diffraction.

SILANE-TERMINATED LIQUID POLY(BUTADIENES) IN TREAD FORMULATIONS: A MECHANISTIC STUDY

2020 ◽  
pp. 000-000
Author(s):  
Fabien Salort ◽  
Steven K. Henning
Keyword(s):  
Molecular Weight ◽  
Viscoelastic Behavior ◽  
Mechanistic Study ◽  
Structure Property ◽  
Silane Coupling Agents ◽  
Chain Entanglement ◽  
Molecular Weights ◽  
Structure Property Relationships ◽  
Silane Coupling ◽  
History Of

ABSTRACT Liquid poly(butadienes) are materials that exhibit flow properties as their molecular weights are at or below that for significant chain entanglement. When applied to tire compound formulation in additive amounts, these low-molecular-weight oligomers are compatible with the elastomeric phase and can influence viscoelastic behavior. The present article will catalogue the history of the use of liquid poly(butadiene) materials in tire compounding, linking their varied application to the evolution of structure–property relationships as a function of microstructure changes. The result of this evolution is the commercialization of functionalized liquid polybutadienes, specifically silane-terminated grades designed for silica-filled systems. It has been found that these materials are not replacements for the typical silane coupling agents ubiquitously used in silica formulating but are rather synergistic with the established technology. The application of silane-terminated liquid poly(butadienes) can both improve traction indicators and limit the negative hysteresis effect commonly associated with the use of liquid poly(butadiene) resins. The mechanism behind the specific changes in viscoelastic and mechanical properties attributed to the addition of silane-terminated liquid poly(butadienes) is explored. It is found that the terminal silane function of the liquid poly(butadienes) may both interact with the silane coupling agent–modified surface of the dispersed silica particles and be available to condense with each other, forming a higher-molecular-weight structure that may effectively increase the apparent crosslink density and therefore bound rubber as an interpenetrating network that extends well into the elastomer phase.

Elastomeric Polyether-Ester Block Copolymers. I. Structure-Property Relationships of Tetramethylene Terephthalate/Polyether Terephthalate Copolymers

1977 ◽  
Vol 50 (4) ◽  
pp. 688-703 ◽  
Author(s):  
J. R. Wolfe
Keyword(s):  
Phase Separation ◽  
Melting Point ◽  
Block Copolymers ◽  
Low Temperature ◽  
Chain Length ◽  
Chemical Structure ◽  
High Water ◽  
Structure Property ◽  
Tear Strength ◽  
Structure Property Relationships

Abstract The properties of elastomeric tetramethylene terephthalate/polyether terephthalate copolymers have been related to the chemical structure, chain length, and concentration in the copolymers of the PTMEG-, PEG-, and PPG-derived polyether units. Low-temperature properties and tear strength are dependent on all three polyether-related variables. Melting point, hardness, and stress at 100% elongation appear to be independent of polyether structure. Polyether glycols of low MW volatilize during copolymer preparation. High-MW polyethers tend to crystallize when present in the copolymers. Polyether glycols of intermediate MW (∼ 1000) yield copolymers with the best resistance to low-temperature stiffening. Copolymer synthesis is most difficult with PPG as the polyether glycol. Inherent viscosities are low, and phase separation occurs at lower polyether MW than with PTMEG or PEG. The PEG-based copolymers exhibit high water swell, particularly at intermediate and high PEG MW. The PTMEG-based copolymers are easiest to synthesize and exhibit the best overall combination of properties.

Nanoporous Polycyanurates Created by Chemically-Induced Phase Separation: Structure-Property Relationships

2014 ◽  
Vol 341 (1) ◽  
pp. 57-66 ◽  
Author(s):  
Olga Grigoryeva ◽  
Alexander Fainleib ◽  
Kristina Gusakova ◽  
Olga Starostenko ◽  
Jean-Marc Saiter ◽  
...  
Keyword(s):  
Phase Separation ◽  
Structure Property ◽  
Structure Property Relationships ◽  
Chemically Induced

Mechanical and Viscoelastic Characterization of Hyperbranched Polyisobutylenes

2002 ◽  
Vol 75 (5) ◽  
pp. 853-864 ◽  
Author(s):  
Judit E. Puskas ◽  
Christophe Paulo ◽  
Volker Altstädt
Keyword(s):  
Molecular Weight ◽  
Butyl Rubber ◽  
Structure Property ◽  
Carbocationic Polymerization ◽  
Molecular Weights ◽  
Structure Property Relationships ◽  
Molecular Weight Distributions ◽  
Weight Distributions ◽  
Living Carbocationic Polymerization

Abstract Structure-property relationships were investigated in hyperbranched polyisobutylenes, in comparison with commercial linear butyl rubber. The gel-free, soluble hyperbranched polyisobutylenes, synthesized by living carbocationic polymerization, had molecular weights, Mw≈400,000 to 1,000,000 g/mol, molecular weight distributions, MWD ≈1.2 to 2.6, and branching frequencies, BR ≈ 4 to 60. The mechanical and viscoelastic characterization of these polymers revealed interesting properties, including the characteristics of crosslinked rubbers.

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