scholarly journals Thermal Transition and Relaxation Behavior of Polybutadiene Polyurethanes Based on 2,6-Toluene Diisocyanate

1982 ◽  
Vol 55 (5) ◽  
pp. 1413-1425 ◽  
Author(s):  
C. M. Brunette ◽  
W. J. MacKnight
Keyword(s):  
Hard Segment ◽  
Strong Dependence ◽  
Melting Process ◽  
Relaxation Behavior ◽  
Toluene Diisocyanate ◽  
Segment Length ◽  
Thermal Transition ◽  
Scanning Calorimetry ◽  
Hard Segment Content ◽  
Melting Endotherm

Abstract The thermal transition and relaxation behavior of a series of segmented polyurethanes based on 2,6-toluene diisocyanate-butanediol hard segments and polybutadiene soft segments have been studied via differential scanning calorimetry and rheovibron measurements. Both techniques show a constant low temperature transition at −54°C corresponding to the Tg of the soft butadiene phase and a hard segment transition at about 62°C, both of which are independent of hard segment content. At higher temperatures, a melting endotherm, Tm1, appears between 140 to 150°C followed by recrystallization and then a final melting process, Tm2, between 190 and 210°C. The positions of the melting peaks and the corresponding heats of fusion, ΔHm, show a strong dependence on hard segment content, annealing temperature and, to a lesser degree, on heating rate. The data indicate that crystals of varying stability are formed at different annealing temperatures. Moreover, only those segments involved in the initial crystal distribution (Tm1) which are long enough will give rise to the higher melting crystals, the size and perfection of which are goverened by the hard segment length.

New Waterborne Polyurethane Dispersions from the Soybean-Oil-Based Polyols by Ring Opening of ESO with Glycol

2011 ◽  
Vol 197-198 ◽  
pp. 1196-1200
Author(s):  
Kun Peng Wang ◽  
Li Ting Yang
Keyword(s):  
Differential Scanning Calorimetry ◽  
Soybean Oil ◽  
Thermophysical Properties ◽  
Ring Opening ◽  
Hard Segment ◽  
Waterborne Polyurethane ◽  
Hardness Testing ◽  
Scanning Calorimetry ◽  
Hard Segment Content ◽  
Polyurethane Dispersions

A series of polyols (GSOLs) with a range of hydroxyl numbers based on epoxidized soybean oil (ESO) were prepared by ring opening with glycol. These Polyols of hydroxyl (OH) numbers ranging from 111 to 162 mg KOH/g were obtained. The environmentally friendly soybean-oil-based waterborne polyurethane dispersions (SPU) with very promising properties have been successfully synthesized from a series of soybean-oil-based polyols (GSOLs) with different hydroxyl numbers by a polyaddition reaction with toluene 2,4-diisocyanate (2,4-TDI). The structure and thermophysical properties of the resulting SPU films have been studied by Fourier transform infrared spectroscopy, differential scanning calorimetry, thermogravimetric analysis, and hardness testing. The experimental results showed that the functionality of the GSOLs and the hard segment content play a key role in controlling the structure and the thermophysical properties of the SPU films.

Effect of cooling induced crystallization upon the properties of segmented thermoplastic polyurethanes

2017 ◽  
Vol 37 (5) ◽  
pp. 471-480 ◽  
Author(s):  
Daniel Ramirez ◽  
Juliana Nanclares ◽  
Marisa Spontón ◽  
Mara Polo ◽  
Diana Estenoz ◽  
...  
Keyword(s):  
Hard Segment ◽  
Chain Extender ◽  
Thermal Transitions ◽  
Scanning Calorimetry ◽  
Force Microscopy ◽  
Thermoplastic Polyurethanes ◽  
Dsc Measurements ◽  
Atomic Force ◽  
Hard Segment Content ◽  
Induced Crystallization

Abstract An investigation on the cooling-induced crystallization in three thermoplastic polyurethanes based on MDI, PTMG, and 1.4-BD as chain extender with different hard segment content is reported. Thermal transitions were determined using differential scanning calorimetry (DSC) measurements at different cooling rates, and thermal stability was studied by thermogravimetric analysis. Changes in Raman spectra were useful to correlate the thermal transitions with changes in the morphology of the polymers. The dissimilarity in the composition gave different rheological behavior in the molten state, indicated by the temperature dependence of the viscosity. The mechanical properties and the crystallinity was influenced not only by the cooling rate but also by the hard segment content. Thermoplastic polyurethanes with more hard segment content formed more crystalline hard domains as evidenced by the DSC and atomic force microscopy results.

scholarly journals The influence of bentonite and montmorillonite addition on thermal decomposition of novel polyurethane/organoclay nanocomposites

2013 ◽  
Vol 32 (1) ◽  
pp. 319 ◽  
Author(s):  
Jelena Pavličević ◽  
Milena Špírková ◽  
Oskar Bera ◽  
Mirjana Jovičić ◽  
Katalin Mészáros Szécsényi ◽  
...  
Keyword(s):  
Thermal Decomposition ◽  
Hard Segment ◽  
Reaction Order ◽  
Hexamethylene Diisocyanate ◽  
Scanning Calorimetry ◽  
Degradation Kinetic ◽  
Polyurethane Elastomers ◽  
Hard Segment Content ◽  
Butane Diol ◽  
Thermal Stability Of

Polycarbonate-based polyurethane (PC-PUs) hybrid materials were obtained by the addition oforganically modified bentonite and montmorillonite (1 w/w %). PC-PUs and their nanocomposites wereprepared using prepolymerization with two polycarbonate diols (both of Mr ca 1000) differing in chainconstitution, hexamethylene-diisocyanate and 1,4-butane diol (chain extender) as starting components. All samples contained the same hard-segment content (30 w/w %). Thermogravimetry coupled with differential scanning calorimetry (TG-DSC) was performed to obtain information about the organoclays addition on the thermal stability of the prepared polyurethane elastomers. The effect of bentonite and montmorillonite nanofillers on the decomposition pattern has been evaluated. By deconvolution of derivative thermogravimetric (DTG) curves, it has been found that the thermal decomposition of polyurethane samples takes place in three overlapping processes. Degradation kinetic parameters (activation energy and reaction order) were calculated on the basis of thermal data obtained at only one heating rate.

scholarly journals Effect of diacylhydrazine as chain extender on microphase separation and performance of energetic polyurethane elastomer

e-Polymers ◽  
2020 ◽  
Vol 20 (1) ◽  
pp. 469-481
Author(s):  
Yang Gao ◽  
Jie Lv ◽  
Licheng Liu ◽  
Yingfeng Yu
Keyword(s):  
Hydrogen Bonding ◽  
Hard Segment ◽  
Microphase Separation ◽  
Low Cost ◽  
Ethylene Carbonate ◽  
Mechanical Analysis ◽  
Chain Extender ◽  
Thermal Transitions ◽  
Scanning Calorimetry ◽  
Hard Segment Content

AbstractIt is low cost and feasible to improve the mechanical properties of polyurethane by using the chain extender with hydrogen bonding function to improve the degree of microphase separation. In this article, hydrazine hydrate was used to react with ethylene carbonate and propylene carbonate, respectively, to synthesize diacylhydrazines as the polyurethane chain extender with amide bonds, which were characterized by 1H nuclear magnetic resonance. Polyurethane with different contents of hard segment were prepared from poly-3,3-bis(azidomethyl)oxetane-tetrahydrofuran as the polyol and 4,4′-diphenylmethane diisocyanate as the isocyanate components. Fourier transform infrared spectroscopy showed that with the increase of the hard segment content, the proportion of hydrogen-bonded ordered carbonyl group increased to 94%, proving that diacylhydrazines could improve the degree of ordered hydrogen bonding, which led to clear microphase separation observed by field emission scanning electron microscopy and higher storage modulus of the polyurethane. Differential scanning calorimetry and dynamic mechanical analysis showed that polyurethane with higher hard segment content is likely to exhibit multiple thermal transitions caused by microphase separation. When the hard segment content was 40%, compared with polyurethane with 1,4-butanediol as the chain extender, the tensile strengths of polyurethanes with diacylhydrazines also improved by 30% and 76%, respectively.

scholarly journals Application of polyurethane in the production of shoe soles

2021 ◽  
Vol 69 (1) ◽  
pp. 7-9
Author(s):  
Ivona Rajić ◽  
Emi Govorčin Bajsić ◽  
Tamara Holjevac Grgurić
Keyword(s):  
Hard Segment ◽  
Carbonyl Groups ◽  
Scanning Calorimetry ◽  
Polyester Polyol ◽  
Oil Resistance ◽  
Hard Segment Content ◽  
Footwear Industry ◽  
Fit For Purpose ◽  
Shoe Soles ◽  
Mechanical Studies

Good footwear should be comfortable, long-lasting and fit for purpose, polyurethanes allow designers to meet all of these objectives. Polyurethanes are used in the footwear industry to make insoles and shoe soles.There are two types of PU soles a polyether and polyester based PU sole. Polyether based PU soles have a high resistance against hydrolysis and low oil resistance while polyester based PU soles have a low resistance against hydrolysis and high oil resistance. In this work thermal and mechanical properties of PU elastomers with polyether and polyester polols with different hard segment content were investigated. Differential scanning calorimetry (DSC) indicated partial crystalinity structure of the PU elastomers. PU elastomers based on polyether type polyol show the higher degree of crystalization. Based on DMAresults , Tgvalues of the PU increases and broadened with increasing hard segment content in the PU elastomers based on polyester polyol, due to the interaction between the urethane groups and the ester carbonyl groups. Mechanical studies indicated that the tensile strength of PU elastomers increased with hard segment.

Effect of chain segment length on crystallization behaviors of poly(l-lactide-b-ethylene glycol-b-l-lactide) triblock copolymer

2019 ◽  
Vol 28 (2) ◽  
pp. 77-88
Author(s):  
Yongji Gong ◽  
Weihua Song ◽  
Yifan Wu ◽  
Daohai Zhang ◽  
Yufei Liu ◽  
...  
Keyword(s):  
Growth Rate ◽  
Ethylene Glycol ◽  
Chain Length ◽  
Triblock Copolymer ◽  
Triblock Copolymers ◽  
Segment Length ◽  
Resonance Spectroscopy ◽  
Chain Segment ◽  
Scanning Calorimetry ◽  
Crystallization Behaviors

The poly(l-lactide-b-ethylene glycol-b-l-lactide) (PLLA-PEG-PLLA) triblock copolymers with different chain segment length are fabricated by ring-opening polymerization. The structure, molecular weight, and crystallization behaviors of the triblock copolymers are characterized by Fourier transform infrared, nuclear magnetic resonance spectroscopy, gel permeation in chromatography, X-ray diffraction, differential scanning calorimetry, and polarizing optical microscopy (POM). The results show that the increase of block length is beneficial to improve its crystallization. In addition, the triblock copolymer exhibits a double crystallization phenomenon. The POM results indicate that PEG and PLLA chains of the copolymer crystallize in their respective crystallization temperature regions. The growth rate of the PLLA spherocrystal decreases and the dendritic spherocrystals appear with increasing the PEG chain length when the PLLA chain of the copolymer is isothermal crystallized at 80°C and PLLA chain length is constant. The growth rate of the PEG spherocrystal decreases and the spherocrystal morphology changes little with increasing PLLA chain length when the PEG chain is isothermal crystallized at 25°C and the length of PEG chain remained unchanged.

Sign in / Sign up

Export Citation Format

Share Document