Properties and Phase Structure of Polycaprolactone‐Based Segmented Polyurethanes with Varying Hard and Soft Segments: Effects of Processing Conditions

Imre, Balázs; Gojżewski, Hubert; Check, Casey; Chartoff, Richard P.; Vancso, Gyula J.

doi:10.1002/macp.201700214

Cited by 20 publications

(23 citation statements)

References 45 publications

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“…Additional morphology investigations of polyurethanes using AFM have also reported the multiscale organization of the hard segments in the polymer [15,17,51,63]. Similar studies as that presented in this paper, show that at low HS content, the morphology is based on dispersed nano-size particles of hard segments and when increasing the HS content to 25 wt%, well defined domains of irregular shape form a hard segments-based network [64,65].…”

Section: Tpu Morphologiessupporting

confidence: 85%

“…For MDI/BDO hard segments, literature reports a glass transition temperature close to 107°C in a polyurethane based on hydrogenated polybutadiene soft segment [10], that is much (Eq.6) higher than the value observed in this study, therefore the phenomenon should presumably not be attributed only to the Tg of the HS. The breakage of hydrogen bonds between urethane NHs and ester carbonyls (present in our polyol) was mentioned in the past as another possible cause [23,51]. Finally, an amorphous interphase composed of mixed soft and hard segments might exist near domain boundaries.…”

Section: (De% Gg)mentioning

confidence: 74%

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On the use of solubility parameters to investigate phase separation-morphology-mechanical behavior relationships of TPU

Gallu

Méchin

Dalmas

et al. 2020

Polymer

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This study proposes a thorough investigation, especially based on thermodynamics, to predict phase separation in a linear thermoplastic polyurethane, denoted TPU, prepared from fatty acid-based soft segments and MDI (4,4'-methylene bis(phenyl isocyanate))/BDO (1,4-butanediol) hard segments and specially designed for bitumen modification. Hansen' solubility parameters (HSP) of both segments are evaluated to predict their compatibility. The later ones are evaluated either individually from the corresponding segment synthesized separately or from a decomposition of the solubility diagram of the TPUs into two distinct spheres. In a second step, phase separation is experimentally analyzed by combining differential scanning calorimetry, microscopy techniques, and small angle X-ray scattering (SAXS). The microstructure of the TPUs is described considering one soft phase

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Section: Tpu Morphologiessupporting

confidence: 85%

Section: (De% Gg)mentioning

confidence: 74%

On the use of solubility parameters to investigate phase separation-morphology-mechanical behavior relationships of TPU

Gallu

Méchin

Dalmas

et al. 2020

Polymer

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“…The high polarity of the urethane bonds promotes phase separation. According to Imre et al [13], segment miscibility increases with an increase in SS polarity. PCL is a well-known hydrophobic polymer, and it can drive phase separation, which explains the FTIR behavior described previously.…”

Section: Resultsmentioning

confidence: 97%

“…As previously mentioned, this peak is related to the associated urethane bonds, suggesting an increase in the interactions between the HS. The PU segmented structures have been reported on as thermodynamically incompatible, producing insolubilities, and phase separation [13]. Shaper peaks could be related to the presence of the HS domain at the point where the spectrum was measured.…”

Section: Resultsmentioning

confidence: 99%

Influence of Polyol/Crosslinker Blend Composition on Phase Separation and Thermo-Mechanical Properties of Polyurethane Thin Films

et al. 2020

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Polyurethanes (PUs) from Polyethylene glycol (PEG) and polycaprolactone diol (PCL) and a crosslinker, Pentaerythritol (PE), were synthetized with isophorone diisocyanate (IPDI). In this study, we investigated the effect of polyol and crosslinker composition on phase separation and thermo-mechanical properties. The properties were studied through dynamic mechanical analysis, X-ray scattering, atomic force microscopy (AFM), and thermogravimetric analysis (TGA). The results showed changes in PUs properties, microphase structure, and separation due to the composition of polyol/crosslinker blend. So, the largest concentration of PE produced multimodal loss factor patterns, indicating segment segregation while PUs with a PEG/PCL = 1 displayed a monomodal loss factor pattern, indicating a homogeneously distributed microphase separation. Additionally, the increase of the PEG concentration enhanced the damping capacity. On the other hand, agglomeration and thread-like structures of hard segments (HS) were observed through AFM. Finally, the thermal behavior of PUs was affected by chemical composition. Lower concentration of PE reduced the crosslinking; hence, the temperature with the maximum degradation rate.Polymers 2020, 12, 666 2 of 13 separation can lead to property changes because SS are responsible for the softness, flexibility, and rubbery behavior, while HS are related to stiffness and mechanical behavior. The elastomeric behavior of PUs results from embedding HS in SS, where the HS acts as crosslinker due to hydrogen bonding [5]. Hence, the segregation of HS and SS mediate PU properties. Aforesaid segregation can be studied by several microscopic, spectroscopic and crystallographic techniques like Atomic force microscopy (AFM), infrared spectroscopy (IR), both small (SAXS) and wide (WAXS) angle X-ray scattering.Previous research has described this segregation as a function of the composition and chemical structure of monomers, and its effect on PU properties. e.g., Klinedinst, D. et al. [4] studied the effects of varying the SS molecular weight and overall HS content thermoplastic segmented PUs. They used AFM and dynamic mechanical analysis (DMA) to identify a thread-like microphase separated structure in chain-extended systems. A higher polyol molecular weight increased the partial crystallization of SS at lower temperatures than room temperature, and larger SS/HS incompatibility, which induced greater microphase separation and a larger storage modulus plateau magnitude. The larger HS mass also increased the temperature at which HS melting occurred, broadening the storage modulus plateau.Some works have focused on the study of the chain extender or crosslinker structure. Like, Kim, H-N., et al.[1] who compared PU microphases with three chain extenders: isosorbide (ISB), isomannide (IMN), and 1,4-butanediol (BD). According to the SAXS results, the scattering widths of IMN and ISB-based PUs were larger than those of BD-based PUs, indicating that the HS domain sizes in the IMN and ISB-based PUs were smaller. It als...

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“…Since the middle of the 20th century, polyurethane elastomer has been widely applied in various industrial settings because of its effective molecular design, high mechanical strength and strong environmental robustness [1][2][3]. For example, in the field of bearing, polyurethane material is referred to as "wear-resistant rubber."…”

mentioning

confidence: 99%

The Synergistic Effect of WS2 and SWNTs on Tribological Performance of Polyether MDI Polyurethane Elastomer under Dry and Wet Friction Conditions

Shuai

Liu

et al. 2022

Nanomaterials

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To adapt to the complex application of polyurethane bearings, it is feasible to improve the tribological performance of single polyurethane-based friction materials through the synergistic effect produced by multi-component-lubricating fillers. In this context, rather than using tungsten disulfide (WS2), which has demonstrated excellent self-lubricating performance as a lubricating oil additive, this paper proposes that WS2 and single-walled carbon nanotubes (SWNTs) can be designed for addition into a polyether 4,4′-diphenylmethane diisocyanate (MDI) polyurethane matrix as self-lubricating fillers so as to explore the synergistic effect of micro- and nano-lubricating fillers on the tribological performance of polyurethane matrix materials. Through a series of characterizations and tests, it was found that the dispersion of two-component-lubricating additives in a polyurethane matrix is improved when the ratio of WS2 to SWNTs is roughly 2:1. In this case, the tribological performance of polyurethane matrix composites is more satisfactory than at other ratios. In addition, compared with the blank sample, the tribological performance of the synergistically modified polyurethane composites under dry friction is more significantly improved with the increase in contact load, while there is no significant improvement under water lubrication. Aside from contributing to the idea of exploring the synergistic effect of WS2 and other micro or nanofillers, this method also opens up the possibility of practically applying WS2 in the field of friction.

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Properties and Phase Structure of Polycaprolactone‐Based Segmented Polyurethanes with Varying Hard and Soft Segments: Effects of Processing Conditions

Cited by 20 publications

References 45 publications

On the use of solubility parameters to investigate phase separation-morphology-mechanical behavior relationships of TPU

On the use of solubility parameters to investigate phase separation-morphology-mechanical behavior relationships of TPU

Influence of Polyol/Crosslinker Blend Composition on Phase Separation and Thermo-Mechanical Properties of Polyurethane Thin Films

The Synergistic Effect of WS2 and SWNTs on Tribological Performance of Polyether MDI Polyurethane Elastomer under Dry and Wet Friction Conditions

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