A study on the synthesis of urethane oligomers

Król, Piotr; Pilch‐Pitera, Barbara

doi:10.1016/s0014-3057(02)00375-0

Cited by 16 publications

(19 citation statements)

References 12 publications

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“…The method for the production of urethane oligomers with controlled molecular weights distribution has already been presented in our earlier reports 26–28. Those oligomers were obtained in a step‐growth polyaddition process which was composed of a few stages and in which excessive amounts of one or the other monomers were used at individual stages.…”

Section: Methodsmentioning

confidence: 99%

“…(2), denoted the prepolymer‐based method for the synthesis of PU (Table I). The sample codification adopted in that study corresponds to that presented in our earlier paper 24–27…”

Section: Methodsmentioning

confidence: 99%

“…Urethane‐isocyanate prepolymers which were obtained from the first stage of the polyaddition process were then extended and crosslinked with the use of triethanolamine, while the urethane‐hydroxyl prepolymers—with the use of 4,4′,4″‐triphenylmethane triisocyanate. PU elastomers with known block structures were produced in this way 26–28. The wide angle X‐ray scattering (WAXS) and scanning electron microscopy (SEM) methods were employed to evaluate morphological patterns of supermolecular structures.…”

Section: Introductionmentioning

confidence: 99%

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Supramolecular structure of crosslinked polyurethane elastomers based on well‐defined prepolymers

Pilch‐Pitera

Król

Pikus

2008

J of Applied Polymer Sci

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This article provides both quantitative and qualitative evaluations of supermolecular structures present in segmented polyurethane elastomers. This work presents our recent results from investigation of the microdomain morphology of poly-(ether-urethanes) based on polyethylene glycol and poly-(ester-urethanes) based on poly-e-caprolactone diol with different molecular weight as soft segments and hard segments based on the combination of TDI and triethanolamine or 4,4 0 ,4 00 -triphenylmethane triisocyanate (Desmodur RE). Those PU elastomers were obtained not only in a typical one-step method but also in the prepolymer method with the use of urethane oligomers with controlled molecular weight distribution (MWD). Prepolymers with well-defined chain structures and narrow distributions of their molecular weights (MWD) M w =M n ¼ 1.1-1.6 were produced in a multistage method, i.e., in step-by-step polyaddition of 2,4-and 2,6-TDI with polyoxyethylenediols or polycaprolactonediols of different molecular weights. Isocyanate oligomers obtained at individual stages were then crosslinked with triethanolamine, whereas hydroxyl-terminated oligomers were crosslinked with Desmodur RE. Microdomain morphology of the soft and hard-segments structure was characterized by means of wide-angle Xray scattering and scanning electron microscope. The phase morphology and microdomain crystallinity were investigated.

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Section: Methodsmentioning

confidence: 99%

“…(2), denoted the prepolymer‐based method for the synthesis of PU (Table I). The sample codification adopted in that study corresponds to that presented in our earlier paper 24–27…”

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Supramolecular structure of crosslinked polyurethane elastomers based on well‐defined prepolymers

Pilch‐Pitera

Król

Pikus

2008

J of Applied Polymer Sci

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“…Isocyanate terminated polyurethane prepolymer is widely prepared from nonequivalent amounts of toluene diisocyanate (TDI) over alcohols. This method is preferred to control chemical composition and molecular weight 1–3. Polyurethane prepolymer can be then extended with diols or diamines to prepare polyurethane or polyurea, respectively 4–7…”

Section: Introductionmentioning

confidence: 99%

A recycling model of excess toluene diisocyanate isomers in the preparation of polyurethane prepolymer

Zhang

et al. 2012

J of Applied Polymer Sci

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Reaction kinetics of dropwise addition of trimethylolpropane (TMP) to toluene diisocyanate (TDI-80) at various temperatures and initial stoichiometry was studied. The progress of the polymerization reaction was monitored by measuring the concentration of isocyanate groups and TDI isomers by means of backtitration and high performance liquid chromatography (HPLC), respectively. The kinetics of dropwise addition method, compared with the conventional one-shot method, was well described by a second order equation. This procedure was optimized by comparing the deviations between experimental data and theoretically calculated data. The effects of temperature, initial stoichiometry and TDI isomers on the amount of excess 2,4-TDI and 2,6-TDI were investigated. Three commercially available TDI mixtures, 65 : 35, 80 : 20, and 100 : 0 ratio of 2,4-TDI/2,6-TDI, respectively, were used. A recycling model of unreacted TDI isomers and solvent was established to reach a stable process and yield polyurethane prepolymer with good reproducibility. This model has been applied in the chemical plant to prepare polyurethane prepolymer with precisely defined chemical compositions in a continuous process.

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“…In chemical terms, PU systems are rather complex due to the highchemical reactivity of isocyanate functions, whereas the presence of water in the atmosphere can result in a number of side reactions, which can affect the properties of the polymers. 12,13 An excess amount of isocyanate may also give rise to side-products, such as urea, polyisocyanurate trimer, biuret, and allophanate.…”

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confidence: 99%

Curing characteristics and mechanical properties of carbon fiber‐interlayered fabric composites based on a polyurethane matrix

et al. 2007

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Polyurethane matrix composites based on fiber-interlayered carbon fabric laminates were prepared by compression molding to assess the feasibility of this approach, when using a highly reactive resin as matrix. The polyurethane matrix was prepared using the excess isocyanate to enhance the PROPERTIES OF CARBON FIBER-INTERLAYERED FABRIC COMPOSITESrigidity of the system through additional crosslinking. The fiber-interlayered laminates consisted of different amount of short fibers between two carbon fabrics. Three composites containing, respectively, 12%, 18%, and 26% wt/wt total carbon fibers were produced for this study. Thermal and IR spectroscopic analysis were performed to select the most suitable thermal curing conditions for the matrix. The results showed that 70• C represents the minimum curing temperature required to carry out the reactions between polyol and isocyanate groups at an economical rate. In this condition, a multistep reaction occurs to consume the excess isocyanate. Mechanical strength of the composites was measured by three-point bending tests, and the data were analyzed by the Weibull statistical method. Fiber content in the interlayer is a critical parameter in the manufacture of these types of composite materials. Composites with 13% and 21% wt/wt short fibers in the interlayers (giving a total carbon fiber content of 18% and 26% wt/wt) exhibit a wider cumulative distribution of strength data due to the restrictions that they impose on the flow of the resin, thereby resulting in an inhomogeneous distribution of resin throughout the samples. A composite with 12% total carbon content (7% wt/wt short fibers) exhibits a narrower cumulative distribution, denoting a greater reliability relative to the manufacturing method used in this study. C

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A study on the synthesis of urethane oligomers

Cited by 16 publications

References 12 publications

Supramolecular structure of crosslinked polyurethane elastomers based on well‐defined prepolymers

Supramolecular structure of crosslinked polyurethane elastomers based on well‐defined prepolymers

A recycling model of excess toluene diisocyanate isomers in the preparation of polyurethane prepolymer

Curing characteristics and mechanical properties of carbon fiber‐interlayered fabric composites based on a polyurethane matrix

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