Physical and chemical cross-linking effects in polyurethane elastomers

Kontou, E.; Spathis, G.; Niaounakis, Michael; Kefalas, V.

doi:10.1007/bf01410405

Cited by 72 publications

(64 citation statements)

References 9 publications

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“…The peaks at 1695 and 1665-1675 cm Ϫ1 are characteristic of free urea carbonyl and hydrogen-bonded urea carbonyl, respectively. 26,27 The concentration of the urea can be analyzed by measuring the intensity of the urea carbonyl peak at 1665-1695 cm Ϫ1 with infrared spectroscopy. However, the peaks of carbonyl groups are broad and overlapped at 1620 -1750 cm…”

Section: Thermal Analysismentioning

confidence: 99%

Properties of rigid polyurethane foams blown by HCFC 141B and distilled water

Jung

Ryu

Kim

et al. 2001

J of Applied Polymer Sci

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Rigid polyurethane foams (PUFs) were prepared from polymeric 4,4Ј-diphenylmethane diisocyanate, polyester polyol, 1,4-butane diol, silicone surfactant, hydrochlorofluorocarbon (HCFC) 141B, and distilled water. The properties and structure of the PUFs were investigated with differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and a universal testing machine. The density of the PUF blown by distilled water and/or HCFC 141B decreased from 175.7 to 28.2 kg/m 3 with an increase of blowing agents. From the SEM results, the average cell size of the PUF blown by distilled water increased from 150 to 290 m with the distilled water content. From the DSC results, the glass-transition temperature (T g ) of the PUF blown by distilled water increased from 85.7 to 101.7°C with increasing distilled water content, whereas the T g of the PUF blown by HCFC 141B remained unchanged with HCFC 141B content. The compressive strength and modulus of the PUF blown by a mixture of distilled water and HCFC 141B was increased from 0.13 to 0.25 MPa and from 3.00 to 7.23 MPa, respectively, with the distilled water content at the sample density of about 44.0 kg/m 3 . The increase of the compressive strength and modulus of the PUF at the same density was related to the increase of the T g from 86.0 to 100.9°C.

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Section: Thermal Analysismentioning

confidence: 99%

Properties of rigid polyurethane foams blown by HCFC 141B and distilled water

Jung

Ryu

Kim

et al. 2001

J of Applied Polymer Sci

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“…More precisely, the samples exhibit a predominant elastic feature, E' being much higher than E" in the whole range of frequencies investigated. However, only the polycarbonate-based sample TPU 7 starts losing its viscous feature at ~10 10 Hz, where E" exhibits a maximum. Moreover, it is interesting to notice that the polyether-based sample TPU 1 differs from the others because of its relatively low moduli, which is probably due to a higher flexibility of the ether bonds in comparison with the ester and carbonate bonds of the other samples.…”

Section: Viscoelastic Behaviormentioning

confidence: 98%

“…The T g , in terms of both its absolute value and its relative position with respect to the operating temperature, certainly affects the erosion rate. In addition, molecular and morphological parameters, such as presence of crosslinks, relative content of hard and soft phase, and degree of phase separation between soft and hard segments (that in turn depends on the molecular weight of the elastomer and its chemical composition) have a strong influence on the erosion behaviour [9,10]. Besides, macroscopic mechanical features affect the solid particle erosion resistance.…”

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confidence: 99%

Solid particle erosion and viscoelastic properties of thermoplastic polyurethanes

Arena¹,

Friedrich

Acierno³

et al. 2015

Express Polym. Lett.

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The wear resistance of several thermoplastic polyurethanes (TPUs) having different chemical nature and micronscale\ud arrangement of the hard and soft segments has been investigated by means of erosion and abrasion tests. The goal was\ud correlating the erosion performances of the materials to their macroscopic mechanical properties. Unlike conventional tests,\ud such as hardness and tensile measurements, viscoelastic analysis proved to be a valuable tool to study the erosion resistance\ud of TPUs. In particular, a strict correlation was found between the erosion rate and the high-frequency (~10^7 Hz) loss modulus.\ud The latter reflects the actual ability of TPU to dissipate the impact energy of the erodent particles

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“…[3] Furthermore, incorporation of starch granules into polyurethane may increase this complication as starch is a polyol containing many hydroxyl groups, which could accelerate the three-dimensional network structure with polyurethane chains by crosslinking. [10][11][12][13][14] The properties of these polymer systems can be determined by the level of grafting of the polyurethane chain with the hydroxyl groups on the surface of the starch granules, as well as the level of the cross-linking of polyurethane chains between the starch granules. The average molecular weight of the homopolymer of the polyurethane separated from the polyurethane incorporated with starch granules could also be another characteristic factor of the properties of the starch-polyurethane system.…”

Section: Introductionmentioning

confidence: 99%

The Cross‐Linking of Polyurethane Incorporated with Starch Granules and their Rheological Properties: Influences of Starch Content and Reaction Conditions

Broecker

2003

Macro Materials & Eng

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Two series of polyurethanes were synthesized using one‐ and two‐step reactions in a bulk phase at 175 °C with polycaprolactone diol, butane‐1,4‐diol, and 4,4‐diphenylmethane diisocyanate (MDI) in a suspension of starch granules to observe cross‐linking phenomena. Scanning electron microscopy (SEM), differential scanning calorimetry (DSC) analysis, and complex viscosity η*(ω), storage G′(ω), and loss‐modulus G″(ω) as rheological measurements, were carried out to characterize the cross‐linking in the polyurethane incorporated with starch. SEM micrographs indicated that grafted polyurethane was cross‐linked between starch granules forming a three‐dimensional network. The plots of η* against ω, and log G′ against log G″ showed that the starch content increased cross‐linking, so as to induce gelation (G′ ≥ G″). However, the cross‐linked networking was decreased over the higher range of starch contents (> 33 wt.‐% for the low hard‐segment series, psb2m3 and > 27 wt.‐% for the high hard‐segment series, psb4m5). Cross‐linking is also enhanced in the high hard‐segment series compared to the low hard‐segment series. Increasing the catalyst concentration also enhanced the cross‐linking inside of the polyurethane phase.Plots of η* against ω for p7s3b4m5(OSR C0.01) and p7s3b4m5(TSR C0.01).magnified imagePlots of η* against ω for p7s3b4m5(OSR C0.01) and p7s3b4m5(TSR C0.01).

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Physical and chemical cross-linking effects in polyurethane elastomers

Cited by 72 publications

References 9 publications

Properties of rigid polyurethane foams blown by HCFC 141B and distilled water

Properties of rigid polyurethane foams blown by HCFC 141B and distilled water

Solid particle erosion and viscoelastic properties of thermoplastic polyurethanes

The Cross‐Linking of Polyurethane Incorporated with Starch Granules and their Rheological Properties: Influences of Starch Content and Reaction Conditions

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