Kinetics of thermal degradation of water borne polyurethane dispersion containing polycaprolactone with either isophorone diisocyanate or metatetramethyl xylene diisocyanate

With isophorone diisocyanate (IPDI) and polyether diols (N210) as raw, the water-borne polyurethane was synthesized. The end groups of the water-borne polyurethane were blocked with 2-hydroxyethyl acrylate (HEA). The chemical structures were characterized from Fourier Transform infrared spectroscopy (FTIR). The viscosity of the emulsion was investigated from rotary viscometer. The kinetics of reaction of NCO blocked with HEA was investigated, the results show that the reaction fits to a second-order reaction characteristic and the reaction rate is irrelevant with HEA.

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Thermal Degradation Kinetics and Modeling Study of Ultra High Molecular Weight Polyethylene (UHMWP)/Graphene Nanocomposite

Molecules ◽

10.3390/molecules26061597 ◽

2021 ◽

Vol 26 (6) ◽

pp. 1597

Author(s):

Iman Jafari ◽

Mohamadreza Shakiba ◽

Fatemeh Khosravi ◽

Seeram Ramakrishna ◽

Ehsan Abasi ◽

...

Keyword(s):

Thermal Stability ◽

Molecular Weight ◽

Thermal Degradation ◽

High Molecular Weight ◽

Degradation Kinetics ◽

Graphene Nanosheets ◽

Thermal Degradation Kinetics ◽

Graphene Nanocomposites ◽

Kinetics Of ◽

Ultra High Molecular Weight

The incorporation of nanofillers such as graphene into polymers has shown significant improvements in mechanical characteristics, thermal stability, and conductivity of resulting polymeric nanocomposites. To this aim, the influence of incorporation of graphene nanosheets into ultra-high molecular weight polyethylene (UHMWPE) on the thermal behavior and degradation kinetics of UHMWPE/graphene nanocomposites was investigated. Scanning electron microscopy (SEM) analysis revealed that graphene nanosheets were uniformly spread throughout the UHMWPE’s molecular chains. X-Ray Diffraction (XRD) data posited that the morphology of dispersed graphene sheets in UHMWPE was exfoliated. Non-isothermal differential scanning calorimetry (DSC) studies identified a more pronounced increase in melting temperatures and latent heat of fusions in nanocomposites compared to UHMWPE at lower concentrations of graphene. Thermogravimetric analysis (TGA) and derivative thermogravimetric (DTG) revealed that UHMWPE’s thermal stability has been improved via incorporating graphene nanosheets. Further, degradation kinetics of neat polymer and nanocomposites have been modeled using equations such as Friedman, Ozawa–Flynn–Wall (OFW), Kissinger, and Augis and Bennett’s. The "Model-Fitting Method” showed that the auto-catalytic nth-order mechanism provided a highly consistent and appropriate fit to describe the degradation mechanism of UHMWPE and its graphene nanocomposites. In addition, the calculated activation energy (Ea) of thermal degradation was enhanced by an increase in graphene concentration up to 2.1 wt.%, followed by a decrease in higher graphene content.

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