Effect of crosslink density on transport of industrial solvents through polyether based polyurethanes

Desai, Sonal; Thakore, I. M.; Devi, Surekha

doi:10.1002/(sici)1097-0126(1998100)47:2<172::aid-pi43>3.0.co;2-2

Cited by 47 publications

(45 citation statements)

References 2 publications

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“…These thermoplastic elastomers exhibit a two-phase morphology, composed of hard segments -formed by the reaction of 4,4′-methylene-bis(phenylisocyanate) (MDI, in the case of both Texins) or hydrogenated MDA (in case of the Tecoflex) and butanediol as chain extender -and soft segments (polyester diols in case of the Texins and polytetramethyleneglycol in case of the Tecoflex). 25, 26 The hard segments act as physical crosslinks, and therefore the mechanical properties as well as the transport of small molecules through these materials depend on the ratio of hard-to-soft phase, i.e., the ratio of chain extender to polyol and the molecular weight of the latter. [27][28][29][30] While the exact chemical compositions of the three commercial TPUs used here are not known, the mechanical data ( Figure S6, tensile storage moduli E′ at 296 K are around 700, 25, and 5 MPa for Texin 270, Texin 285, and Tecoflex, respectively, cf.…”

Section: Resultsmentioning

confidence: 99%

Influence of Temperature on Low-Power Upconversion in Rubbery Polymer Blends

et al. 2009

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Abstract:The upconverting properties of a dye cocktail composed of palladium(II) octaethylporphyrin (PdOEP, triplet sensitizer) and 9,10-diphenylanthracene (DPA, triplet acceptor/annihilator) were investigated as a function of temperature in several low glass transition temperature (T g ) polymer hosts including an ethyleneoxide-epichlorohydrin copolymer (EO-EPI) and the polyurethanes Texin 270, Texin 285, and Tecoflex EG-80A. Selective excitation of PdOEP at 544 nm in the presence of DPA in these materials resulted in anti-Stokes blue emission from DPA, a consequence of sensitized triplet-triplet annihilation (TTA) photochemistry, confirmed by the quadratic dependence of the upconverted fluorescence intensity with respect to incident light power. The upconversion process was completely suppressed by cooling a PdOEP/DPA blend film to below the T g of the respective polymer. However, the blue emission was clearly visible by the naked eye upon heating these films to room temperature (290 K). Subsequently, the upconverted emission intensity increased with increasing temperature and was found to be completely reversible upon several heating and cooling cycles provided the temperature remained below 400 K. Heating samples above this temperature resulted in unrecoverable failure of the material to produce upconverted photons. The phosphorescence intensity decay of PdOEP in the polymer host, Tecoflex EG-80A, adequately fits to a sum of two exponential functions as well as the Kohlrausch-Williams-Watts (KWW) stretched exponential model. Increasing the temperature of the film increases the complexity and heterogeneity of the system as evidenced by the lower values obtained from the KWW model as the temperature increases.

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Section: Resultsmentioning

confidence: 99%

Influence of Temperature on Low-Power Upconversion in Rubbery Polymer Blends

et al. 2009

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“…From the results, the χ values follow the sequence of hexane > methanol > ethanol > toluene. This indicates that UP has higher interaction with toluene, consequently greater sorption, as observed in the S value [29]. According to Flory–Huggins's theory, to obtain a completely miscible system, the χ value must be less than 0.5.…”

Section: Resultsmentioning

confidence: 99%

Palm oil‐based unsaturated polyester: Activation energy and swelling properties

Lai

Rozman

Tay

2012

Polymer Engineering & Sci

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In this study, unsaturated polyester (UP) resin based on palm oil was synthesized. Palm oil monoglyceride (POMG) was obtained by alchoholysis process of palm oil at 230°C for 3 h. Then, POMG was treated with maleic anhydride (MA) at different ratio of POMG:MA to produce UP resin. The products were then characterized using Fourier transform infrared (FTIR) spectrometer and proton nuclear magnetic resonance (1H‐NMR) spectrometer. FTIR and 1H‐NMR spectrum analyses confirmed that the unsaturated group of MA was chemically attached to POMG. The activation energy of POMG/MA reaction was also studied. The results showed that the ratio of reactants and the presence of 2‐methylimidazole influenced the activation energy of reaction. The prepared UP resin was mixed with 35% of styrene, 0.3% of cobalt naphthenate, and 1% of methyl ethyl ketone peroxide before it was subjected to curing process. The effect of POMG/MG ratio on swelling properties of the cured UP was studied, and the result indicated that toluene and cured UP resin were compatible. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers

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“…Sorption coefficient is related to the maximum sorption of the solvent that can be obtained from the ratio of weight of the solvent absorbed at equilibrium stage to the initial weight of the polymer 14. The sorption coefficient ( S ) of the EFB‐PU composites can be calculated using equation shown below15, 16: where M s = mass of solvent absorbed at equilibrium swelling (in gram); M p = mass of the composite at initial state (in gram).…”

Section: Methodsmentioning

confidence: 99%

The effects of NCO/OH ratio on propylene oxide‐modified oil palm empty fruit bunch‐based polyurethane composites

Rozman

Tay

2008

J of Applied Polymer Sci

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In this study, the effects of NCO/OH ratio on polyurethane composites prepared from propylene oxide-modified oil palm empty fruit bunch (EFB-PO) properties were studied. From the results obtained, the diffusion of solvents in the composites produced was classified as Fickian type. The molecular weight between crosslink points and degree of crosslinking were affected as the NCO/OH was increased. This phenomenon was attributed to the interaction between excess NCO and accessible OH groups from EFB-PO to form a three-dimensional network. From the mechanical testing results, it was found that the NCO/OH ratio had a significant effect on tensile and flexural test. However, no significant influence was observed on impact strength of the composites produced.

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Effect of crosslink density on transport of industrial solvents through polyether based polyurethanes

Cited by 47 publications

References 2 publications

Influence of Temperature on Low-Power Upconversion in Rubbery Polymer Blends

Influence of Temperature on Low-Power Upconversion in Rubbery Polymer Blends

Palm oil‐based unsaturated polyester: Activation energy and swelling properties

The effects of NCO/OH ratio on propylene oxide‐modified oil palm empty fruit bunch‐based polyurethane composites

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