Structure-property relationship of blocked diisocyanates: synthesis of polyimides using imidazole-blocked isocyanates

Subramani, Sankaraiah; Nasar, A. Sultan; Gnanarajan, T. Philip; Iyer, N. Padmanabha; Radhakrishnan, Ganga

doi:10.1002/1097-0126(200006)49:6<546::aid-pi431>3.0.co;2-c

Cited by 31 publications

(16 citation statements)

References 20 publications

(16 reference statements)

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“…The absorption in 34202430 cm 21 and 1577 cm 21 attributed to N-H linkages 18,19 appears in the spectrum of EMI rather than that of the EMI derivatives, suggesting N-H bond from EMI reacted with the acyl chloride from the modifier. NAEMI and NBEMI show characteristic absorption of 20 Peaks at 29802840 cm 21 are attributed to the C-H stretching of the imidazole ring and the aliphatic chain. 21 These peaks confirm the reaction between the secondary amine of EMI and the acyl chloride groups of N-acetyl chloride, N-benzoyl chloride, and N-benzenesulfonyl chloride as shown in Scheme 2.…”

Section: Structure Of the Emi Derivativesmentioning

confidence: 99%

Preparation of 2‐ethyl‐4‐methylimidazole derivatives as latent curing agents and their application in curing epoxy resin

Lei

Wang

et al. 2015

J of Applied Polymer Sci

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Three kinds of 2-ethyl-4-methylimidazole (EMI) derivatives (N-acetyl EMI, N-benzoyl EMI, and N-benzenesulfonyl EMI) were synthesized through the reaction of EMI with acetyl chloride, benzoyl chloride, and benzenesulfonyl chloride, respectively. And the structure was confirmed by Fourier transform infrared spectroscopy (FTIR) and 1 H-nuclear magnetic resonance spectroscopy ( 1 H NMR) spectra. Furthermore, the synthesized EMI derivatives were applied in diglycidyl ether of bisphenol A epoxy resin (DGEBA) as latent curing agent. Differential scanning calorimeter (DSC) was used to analyze the curing behavior of DGEBA/EMI derivative systems, indicating DGEBA could be efficiently cured by the EMI derivatives at 1101608C, and the corresponding curing activation energy ranged from 71 to 86 kJ/mol. Viscosity data proves that the storage life of DGEBA with N-acetyl EMI (NAEMI), N-benzoyl EMI (NBEMI), and N-benzenesulfonyl EMI (NBSEMI) at room temperature was 38 d, 50 d, and 80 d, and that at 108C was 90 d, 115 d, and 170 d, respectively. Besides, thermogravimetry (TG), izod impact strength (IIS), and tensile shear strength (TSS) were tested to characterize the thermal stability and mechanical properties of DGEBA cured by EMI derivatives.

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Section: Structure Of the Emi Derivativesmentioning

confidence: 99%

Preparation of 2‐ethyl‐4‐methylimidazole derivatives as latent curing agents and their application in curing epoxy resin

Lei

Wang

et al. 2015

J of Applied Polymer Sci

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“…Imidazole/imidazoline Imidazole 64,86 Basicity of imidazole able to accelerate the blocking reaction without additional catalyst. 22 Large substituent effect on deblocking temperature. 87…”

Section: -145 N-hydroxyphthalimide 85mentioning

confidence: 99%

Blocked isocyanates: from analytical and experimental considerations to non-polyurethane applications

et al. 2016

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“…Both aliphatic and aromatic isocyanates can be blocked by a variety of blocking agents. The most widely commercially used agents are phenols, oximes, alcohols, ε-caprolactam, dibutyl malonate, amides and imides (22)(23)(24)(25). The deblocking temperature of the blocked isocyanates is of vital importance in industrial applications.…”

Section: Introductionmentioning

confidence: 99%

Preparation and Properties of Non-ionic Polyurethane Crosslinkers from 2-Ethoxyethanol/ϵ-caprolactam-Blocked Diisocyanate

Shen

Liang

2012

Journal of Macromolecular Science, Part A

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A series of novel water-based non-ionic blocked polyurethane crosslinker (n-BPUC) dispersions have been synthesized by the reaction of toluene 2,4-diisocyanate (TDI), isophorone diisocyanate (IPDI), polyethylene glycol (PEG), 1,1,1-trimethylolpropane (TMP), 2-Ethoxyethanol (2-Et) and ε-caprolactam (CL). The physical properties of prepared n-BPUC dispersions such as viscosity, pH, and storage stability are measured and compared. The chemical structure of the prepared n-BPUC dispersions is confirmed by Fourier transform infrared spectroscopy (FTIR) and gel permeation chromatography (GPC). Deblocking temperatures of the n-BPUC dispersions are analyzed by differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA) techniques. The thermal analysis reveals that deblocking temperature obtained by DSC and TGA techniques is compared and found to be in the order DSC < TGA. Based on DSC and TGA data, it is shown that deblocking of n-BPUC dispersions based on 2-Et start at lower temperatures compared to that of the ones based on CL. The TDI-based n-BPUCs show higher reactivity than the ones based on IPDI. Hydroxyl-terminated polyurethane (HPU) is introduced to estimate the crosslinking effect of the prepared n-BPUCs. The better tensile properties and water resistance of n-BPUC modified HPU films compared to pure HPU film demonstrate the good crosslinking effect of the prepared n-BPUCs.

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Structure-property relationship of blocked diisocyanates: synthesis of polyimides using imidazole-blocked isocyanates

Cited by 31 publications

References 20 publications

Preparation of 2‐ethyl‐4‐methylimidazole derivatives as latent curing agents and their application in curing epoxy resin

Preparation of 2‐ethyl‐4‐methylimidazole derivatives as latent curing agents and their application in curing epoxy resin

Blocked isocyanates: from analytical and experimental considerations to non-polyurethane applications

Preparation and Properties of Non-ionic Polyurethane Crosslinkers from 2-Ethoxyethanol/ϵ-caprolactam-Blocked Diisocyanate

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