The chemical modification of commodity polymers such as polyethylene (PE) is a versatile synthetic approach for preparing materials that cannot be manufactured cost-effectively using conventional polymerization techniques. Aiming to improve PE character low contents of dicumyl peroxide (DCP), from 0% to 1.5% was added as crosslinker to an industrial batch (PEs mixture and additives). From tensile testing crosslinking provided higher elastic modulus most due to the restrained microstructure where XPEs macromolecular chains are interconnected also providing lower strain at break. Crosslinking effects on the nonisothermal melt crystallization rate (Cmax) and degree of crystallinity (Xc) were

This work investigated the curing and degradation behavior of compounds made with 1:1 of bisphenol A diglycidyl ether and epoxidized soybean oil, cured with itaconic acid (ITA) and succinic acid (SUC), coded as EP/ITA and EP/SUC. Complex peaks observed in differential scanning calorimetry are mostly due to the catalyzed curing and homopolymerization. Fourier transform infrared spectroscopy spectra suggest that the curing follows the SN 2 reaction mechanism for both compounds. Lower activation energies of curing were verified for EP/ITA compared to the EP/SUC, mainly due to their greater reactivity with the epoxy matrix at temperatures below the acids structures and melting points. Regarding thermal degradation, four steps were verified: acid degradation, degradation of the non-cross-linked material, degradation of cross-linked material, and carbon decomposition. EP/SUC with a molar ratio equal to 0.4 presented the lowest activation energy for degradation. The degradation's solid-state mechanisms analysis indicated that in EP/ITA and EP/SUC compounds the processes are controlled by nucleation and subsequent growth.

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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.

This work deals with the degradation kinetics of epoxidized soybean oil, whereas the weight loss of epoxidized soybean oil (ESO) cured with methyl tetrahydrophthalic anhydride (MTHPA) as hardener and 2,4,6‐tris (dimethylaminomethyl) phenol (DEH 35) as catalyst displayed two main regions in the thermogravimetry (TG) plots. Nevertheless, deconvolution of the weight loss plots presented three or more events depending on the composition and experimental parameters. Increase the MTHPA addition led to a decrease in the activation energy (AE) for curing which conducted to an increased AE during the degradation. Friedman's isoconversional model exhibits proper R2 for the curing kinetics, but lower R2 values for lower anhydride contents during the degradation kinetics analyses. Kissinger‐Akahira‐Sunose (KAS) and Ozawa‐Flynn‐Wall (OFW) models displayed the best R2 during the kinetics evaluation, whereas the degradation mechanisms fitted reasonably with Avrami‐Erofeev (An) and nth‐order autocatalytic (Cn) during the first and second weight loss regions. Microstructural analyzes and in‐depth investigations into the thermal degradation mechanism of ESO suggest two possible pathways, that is, production of carbonic groups through heterolytic scission, and formation of electrically stable groups with saturated carbon bonds.

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.