On the Curing of ESO/MTHPA/DEH 35 and ESO/MTHPA/DEH 35/TIN

Severo, Amanda M. C.; Nicácio, Pedro H. M.; Fook, Marcus Vinícius Lia; Wellen, Renate Maria Ramos

doi:10.1007/s10924-022-02489-z

Cited by 5 publications

(4 citation statements)

References 30 publications

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“…For PU without ISO (Figure 5A) there is a shift of the melting peaks to the right increasing the heating rate, it goes from 55 to 59°C. This behavior suggests that the PU melting subtly depends on the heating rate, which slows down due to the time delay effect 46,47 . For ISOPUs a similar trend was observed, Figure S2 (Supplementary Material).…”

Section: Resultssupporting

confidence: 69%

“…At 5 C/ min, ΔH increased from 125 to 158 J/g, for 10% ISO to 70% ISO, that is, there is an increase of 33 J/g in the released heat, which contributes for higher degrees of conversion. This trend can be linked to the increase in the crosslinks between PDI and ISO, elucidating the influence of NCO/OH ratio, 46,51 and corroborating the data observed in the FTIR spectra. In Figure 8B the real conversion is presented as function of the ISO content for the four applied heating rates.…”

Section: Fourier Transform Infrared Measurementssupporting

confidence: 79%

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Synthesis, curing, and degradation kinetics of polyurethanes based on poly(ethylene glycol), isosorbide, and pentamethylene diisocyanate

Araújo

Barreto

Nicácio

et al. 2023

Polymers for Advanced Techs

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Polyurethane (PU) synthesis based on poly(ethylene glycol) (PEG) with isosorbide (ISO) and pentamethylene diisocyanate (PDI), named (ISOPUs) was carried out targeting PUs from renewable sources. The cross-linked ISOPUs were produced and the details of the curing kinetics were determined via Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). DSC scans displayed exotherms between 100 and 200 C, related to cross-linking. ISO addition accelerated the curing and the maximum curing rate (Cmax), with 91 C and 0.2964 min À1 for the compound with 70% ISO. FTIR spectra confirmed the interaction between OH (ISO/PEG) and NCO (PDI) groups, with total NCO consumption (band at 2267 cm À1 ).Through the thermogravimetric analyses (TGA), the PU/70% ISO presented weight loss at 146 C due to the degradation of ISO. ISOPUs displayed a decreased activation energy (Ea) during curing over a range of 100 to 42 kJ/mol for 0 < α < 5%, as demonstrated using the Friedman model, and higher thermal stability as evidenced through TG analyses. Curing and degradation kinetics were modeled using Friedman (FR), Kissinger-Akahira-Sunose (KAS), and Ozawa-Flynn-Wall (OFW). Overall, ISO accelerated the curing rate and increased the degradation Ea, suggesting high thermal stability for PUs with intermediate ISO contents, that is, 30%-50%. K E Y W O R D S biobased polyurethane, curing and degradation kinetics, Isosorbide, pentamethylene diisocyanate, poly(ethylene glycol) 1 | INTRODUCTION Polyurethanes (PU) based on renewable sources, such as bio-based polyols and diisocyanates are being synthesized with the objective to replace PUs from non-renewable sources, such as petroleum, and to reduce the use of toxic isocyanates. The synthesis of bio-based PUs from alternative resources, such as glucose has been growing considerably due to its potential to modify the mechanisms of curing and degradation, providing greater chemical, and physical stability. 1-4 In this context, Wang et al. 5 successfully cross-linked thermosetting PUs through the reaction of a bio-based diol with a monocyclic acetal structure and a trifunctional isocyanate reinforced with carbon fibers.The resulting material presented higher performance for application in the automotive, aerospace, and sports equipment industries.Polyurethanes synthesis takes place through urethane bonds by the polymerization of flexible segments (polyether or polyester), known as polyols, which have one or more OH groups, and rigid segments (diisocyanates) which have two or more NCO groups.

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Section: Resultssupporting

confidence: 69%

Section: Fourier Transform Infrared Measurementssupporting

confidence: 79%

Synthesis, curing, and degradation kinetics of polyurethanes based on poly(ethylene glycol), isosorbide, and pentamethylene diisocyanate

Araújo

Barreto

Nicácio

et al. 2023

Polymers for Advanced Techs

Self Cite

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“…For a better understanding of the curing conversion ( α ) of ESO/MTHPA/DEH35, ESO/MTHPA/DEH35/S10, and ESO/MTHPA/DEH35/S30, the degree of conversion was calculated using the modified Beer–Lambert Law through FTIR spectra integration using Fityk software, the curing rate profile (d α /dt) was determined, the acquired data are presented in Figure 5. The band adopted as reference was 2917 cm −1 (associated with C–H axial stretching), since it is not involved in the curing, remaining stable during the whole process 42 . The band at 900 cm −1 (associated with the epoxide group stretching vibration) was adopted for the curing conversion, since the gradual decrease points to the epoxide ring opening.…”

Section: Resultsmentioning

confidence: 99%

“…For ESO/MTHPA/DEH35 there are two weight loss events, the first one in the range of 60–260°C corresponding to the moisture evaporation, followed by the thermal decomposition of low molecular weight compounds, that is, unreacted DEH 35 and MTHPA. The second weight loss event is marked by the ESO decomposition in the range of 267–500°C 42 …”

Section: Resultsmentioning

confidence: 99%

Degradation kinetics of epoxidized soybean oil composites filled with sisal fiber

Severo,

Barreto,

Nicácio

et al. 2023

J of Applied Polymer Sci

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Epoxidized soybean oil (ESO) composites were cured with methyl tetrahydrophthalic anhydride (MTHPA) and 2,4,6‐tris(dimethylaminomethyl)phenol (DEH 35) as a catalyst, sisal fibers were added at 10% and 30% of percent per weight. Composites curing was monitored using Fourier transform infrared spectroscopy, whereas the thermal stability and the degradation kinetics were investigated using thermogravimetry (TG). ESO/MTHPA/DEH35/S10 and ESO/MTHPA/DEH35/S30 composites displayed curing temperatures approximately 100°C lower related to ESO/MTHPA/DEH35, as well as higher degree of conversion. Sisal addition improved the thermal stability, shifting the weight loss shifting the weight loss onset to higher temperature (from 82 to 120°C). Thermal degradation energy was determined using Friedman, Kissinger‐Akahira‐Sunose and Ozawa‐Flynn‐Wall models. Sisal significantly increased , especially in the intermediate phase (α = 0.2 and 0.8). The degradation kinetics was investigated by TG, and the degradation mechanisms modeled using Kamal‐Sourour, Sestack‐Berggren, and 1st order (F1), showed excellent fit, with R2 > 0.99. Acquired results demonstrate that sisal fiber addition benefited the curing process and increased the thermal stability of ESO composites.

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Effect of hardener and catalyst contents on curing and degradation of epoxidized soybean oil

Albuquerque

Almeida

Barreto

et al. 2022

J of Applied Polymer Sci

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Epoxidized soybean oil (ESO) compounds were cured with methyl tetrahydrophthalic anhydride (MTHPA) as hardener and 2,4,6-tris (dimethylaminomethyl) phenol (DEH 35) as catalyst. To figure out MTHPA and DEH 35's influence during curing and degradation, ESO/MTHPA/DEH 35 compounds were investigated using Fourier-Transform Infrared Spectroscopy (FTIR), differential scanning calorimetry (DSC), and thermogravimetry (TG).FTIR spectra of uncured resin showed the secondary interactions among ESO's carbonyl groups with MTHPA and DEH 35's hydroxyls and amines. Curing progress was followed tracking the evolution of reactive groups, that is, epoxy and carbonyl bands and corroborated with released heat of DSC scans. ESO 87:5 and ESO 87:10 compounds cured using higher heating rates presented higher released enthalpy suggesting denser reticulation, and they also displayed lower activation energy E a ð Þ for curing, which was evaluated using the Friedman model. Increasing the hardener and catalysts contents promoted higher thermal stability and lower degradation rates, while higher E a for degradation was verified.

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On the Curing of ESO/MTHPA/DEH 35 and ESO/MTHPA/DEH 35/TIN

Cited by 5 publications

References 30 publications

Synthesis, curing, and degradation kinetics of polyurethanes based on poly(ethylene glycol), isosorbide, and pentamethylene diisocyanate

Synthesis, curing, and degradation kinetics of polyurethanes based on poly(ethylene glycol), isosorbide, and pentamethylene diisocyanate

Degradation kinetics of epoxidized soybean oil composites filled with sisal fiber

Effect of hardener and catalyst contents on curing and degradation of epoxidized soybean oil

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