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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−1 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−1). 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%. [ABSTRACT FROM AUTHOR]

Synthesis of bio‐polyurethane (Bio‐PU) using isosorbide (ISO) and poly(lactic acid) (PLA) diols, (propanediol based poly(lactic acid) (PLAP) and PLA esterified with Soybean oil (PLASO)) and pentamethylene (PDI) isocyanate were performed. Crosslinked Bio‐PUs were obtained, and the details of the curing kinetics were determined via Fourier transform infrared spectroscopy (FTIR) spectra and differential scanning calorimetry (DSC). Distinct curing behaviors between Bio‐PUs with different PLA diol formulations were observed. The addition of PLAP and PLASO increased the curing conversion at approximately 460% higher than Bio‐PU without PLA content, as verified by FTIR. The curing peak temperature (Tp) of Bio‐PUs with PLAP ranged from 94 to 163°C, while for PLASO Tp was 132–175°C. Bio‐PUs based on PLA diols displayed lower activation energy (Ea) during curing as demonstrated using Friedman model, and higher thermal stability as evidenced through thermogravimetric analyses. Reported data offer reliable tools to evaluate the best rote to synthesize biobased polyurethane and manipulate the degree of crosslinking based on composition and processing conditions, allowing product processing to the desired application. [ABSTRACT FROM AUTHOR]

The effect of poly(lactic acid) (PLA) content on the curing of polyethylene glycol (PEG) based polyurethanes (PU) was investigated. Aiming to produce biobased PU foams, pentamethylene diisocyanate (PDI) was used. Fourier transform infrared spectroscopy (FTIR) found no curing evidence at 30°C and verified that the curing was completed at 300°C. This method tracks hydrogen bonding and NCO consumption. PLA addition decreased the curing rate as evidenced through differential scanning calorimetry (DSC) and promoted changes in the released heat which is linked to chemical and physical crosslinking. Complex peaks were verified in DSC scans whereas the peak at lower temperatures is related to the catalyzed curing while that in the higher ones is due to the homopolymerization. PU foams morphology was investigated using scanning electron microscopy (SEM). Pores and cell sizes are related to PLA content and hydrogen bonding. [ABSTRACT FROM AUTHOR]

In this work, poly(lactic acid) (PLA)-based vegetal Babassu composites were compounded and their thermal properties ascertained. Babassu acted as a facilitator agent for the nonisothermal cold crystallization of PLA. Nonisothermal cold crystallization kinetics of PLA compounds was investigated by differential scanning calorimetry applying Ozawa and Mo models; the activation energy was evaluated by Friedman equation. Our results indicate that Mo's model describes the experimental data successfully; the maximum crystallization rates observed for PLA/Babassu composites are higher than that found for neat PLA. Ozawa model failed to provide an adequate description for the composites, mostly due to the neglected secondary crystallization and impingement of spherulites. Friedman analysis shows that 5 wt% Babassu filler reduced the activation energy of the crystallization process greatly, leading to a shorter crystallization time. [ABSTRACT FROM AUTHOR]

Compounds of poly(3-hydroxybutyrate) (PHB) and zinc oxide with filler content between 1 and 10% were prepared in a laboratory internal mixer. The effect of heating and cooling rates on the crystallization and melting of PHB/ZnO compounds was investigated by differential scanning calorimetry. Physical aspects of the compounds were examined by means of scanning electron microscopy and optical microscopy. Melt and cold crystallization rates rise with increasing cooling/heating rates. The melt crystallization temperatures and maximum melt crystallization rates are almost unaffected by the filler, independent on the filler concentration. The main effect of ZnO on PHB is to reduce the overall crystallinity obtained after a successive melt and cold crystallization events. For defined filler content, Mo model can be applied for the description of tested and untested heating/cooling rates, provided that a lower accuracy is acceptable. [ABSTRACT FROM AUTHOR]