Model hard segments from diphenyl methane diisocyanate and different chain extenders, and corresponding linear block polyurethanes

1982 ◽  
Vol 20 (6) ◽  
pp. 1445-1456 ◽  
Author(s):  
Y. Camberlin ◽  
J. P. Pascault ◽  
J. M. Letoffé ◽  
P. Claudy
Keyword(s):  
Chain Extenders ◽  
Hard Segments ◽  
Linear Block

Association of hard segments in gas separation through polyurethane membranes with aromatic bulky chain extenders

2019 ◽  
Vol 574 ◽  
pp. 136-146 ◽  
Author(s):  
Afsaneh Fakhar ◽  
Morteza Sadeghi ◽  
Mohammad Dinari ◽  
Rob Lammertink
Keyword(s):  
Gas Separation ◽  
Polyurethane Membranes ◽  
Chain Extenders ◽  
Hard Segments

scholarly journals Effects of Diisocyanate Structure and Disulfide Chain Extender on Hard Segmental Packing and Self-Healing Property of Polyurea Elastomers

Polymers ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 838 ◽  
Author(s):  
Ting Li ◽  
Tianze Zheng ◽  
Jiarui Han ◽  
Zhanli Liu ◽  
Zhao-Xia Guo ◽  
...  
Keyword(s):  
Disulfide Bonds ◽  
Aliphatic Amine ◽  
Chain Extender ◽  
Hexamethylene Diisocyanate ◽  
Self Healing ◽  
Segmental Dynamics ◽  
Chain Mobility ◽  
Healing Property ◽  
Chain Extenders ◽  
Hard Segments

Four linear polyurea elastomers synthesized from two different diisocyanates, two different chain extenders and a common aliphatic amine-terminated polyether were used as models to investigate the effects of both diisocyanate structure and aromatic disulfide chain extender on hard segmental packing and self-healing ability. Both direct investigation on hard segments and indirect investigation on chain mobility and soft segmental dynamics were carried out to compare the levels of hard segmental packing, leading to agreed conclusions that correlated well with the self-healing abilities of the polyureas. Both diisocyanate structure and disulfide bonds had significant effects on hard segmental packing and self-healing property. Diisocyanate structure had more pronounced effect than disulfide bonds. Bulky alicyclic isophorone diisocyanate (IPDI) resulted in looser hard segmental packing than linear aliphatic hexamethylene diisocyanate (HDI), whereas a disulfide chain extender also promoted self-healing ability through loosening of hard segmental packing compared to its C-C counterpart. The polyurea synthesized from IPDI and the disulfide chain extender exhibited the best self-healing ability among the four polyureas because it had the highest chain mobility ascribed to the loosest hard segmental packing. Therefore, a combination of bulky alicyclic diisocyanate and disulfide chain extender is recommended for the design of self-healing polyurea elastomers.

Synthesis of thermally and mechanically improved polyurethane-urea elastomers by using novel diamines as chain extenders

e-Polymers ◽  
2016 ◽  
Vol 16 (5) ◽  
pp. 411-418 ◽  
Author(s):  
Muhammad Shoaib ◽  
Ali Bahadur
Keyword(s):  
Hard Segment ◽  
Mechanical Test ◽  
Reference Sample ◽  
Thermal Stabilization ◽  
Urea Group ◽  
Chain Extenders ◽  
Stabilization Effect ◽  
Hard Segments ◽  
Reflectance Ftir ◽  
Atr Spectroscopy

AbstractThis article reports the synthesis of novel diamines as chain extenders for the improvement of thermal and mechanical properties of polyurethane (PU). Three novel diamine, 1,2-di(p-aminophenoxy)ethane (BAE), 1,2-di(p-aminophenoxy)propane (BAP) and 2,2-bis(p-(p-aminophenoxy)phenyl)propane (BAPP) were synthesized as chain extenders. Formation of diamines and their reaction with PU prepolymer was analyzed by using Fourier transform infrared attenuated total reflectance (FTIR-ATR) spectroscopy. The conversion of the free isocyanate group (NCO) into a urethane-urea group was confirmed through the disappearance of the isocyanate peak at 2244 cm-1. The thermogravimetric analysis (TGA) reveals the thermal stabilization effect of urethane-urea hard segments of the polyurethane system. From the SAXS investigations, the hard segment inter-domain spacing (d) was calculated, which was 24 nm for the reference sample, and 25, 26, and 28.5 nm for the synthesized PU systems. Mechanical test shows an increase in the Young’s modulus and yield strength with BAE and BAP diamines, while BAPP diamine based systems reveal lower modulus values as compared to the reference sample.

Biodegradable Polyurethanes Cross-Linked by Multifunctional Compounds

2017 ◽  
Vol 14 (6) ◽  
pp. 778-784 ◽  
Author(s):  
Joanna Brzeska
Keyword(s):  
Polymer Structure ◽  
Cross Linking ◽  
Plant Oils ◽  
Lignocellulosic Materials ◽  
Soft Or ◽  
Native State ◽  
Synthetic Compounds ◽  
Multifunctional Compounds ◽  
Hard Segments ◽  
Synthetic Origin

Background: Cross-linking structure of polyurethanes determines no degradability of these materials. However, introducing the hydrolysable substrates (of natural or synthetic origin) into the cross-linked polyurethanes structure makes them biodegradable. Moreover compounds (such as polycaprolactone triol, glycerin, lysine triisocyanate, etc.) that are used for polyurethane cross-linking are degraded in non-toxic products. All these kinds of compounds can be introduced into soft or hard segments via urethane bonds. Objective: The review focuses on kind of multifunctional polyols and isocyanates, and low molecular crosslinkers used for cross-linked polyurethanes obtaining. These compounds are natural substrates (in the native state or after modification) or are synthetic compounds with degradable linkages. They belong to polyesters, plant oils, proteins, saccharides, and others (e.g. lignocellulosic materials), and they are synthesized chemically or via biosynthesis by algae, plants, microorganisms, and by animals. Conclusion: Incorporation of degradable groups (such as ester moieties) into the polymer structure, and using of substrates with the structure known and metabolized by microorganisms for soft or hard segments building, facilitate degradation of cross-linked polyurethanes.

Miscibility and Crosslinking of Polybutadiene-Based Polyurethanes

2000 ◽  
Vol 65 (11) ◽  
pp. 1820-1832
Author(s):  
Miloslav Pekař ◽  
Pavel Kopecký
Keyword(s):  
Phase Structure ◽  
Initial Mixture ◽  
Cooperative Effect ◽  
Final Phase ◽  
Elastic Part ◽  
Hard Segments

Rheokinetics of polybutadiene-based polyurethanes was studied. Sixteen mixtures differing in the miscibility of reactive components and hard segments contents were prepared. Regardless of the miscibility of the components, the rheokinetics behaviour is qualitatively very similar. The viscous response part is formed and finished much earlier than the elastic part. The quantitative dissimilarities, caused by cooperative effect of miscibility and differences in reactivity, are described. Using a well miscible initial mixture need not give the best results as a reactive crosslinker can easily react with isocyanate and separate from the rest of the reaction mixture thus impairing the final phase structure.

Sign in / Sign up

Export Citation Format

Share Document