Segmental Relaxation Dynamics in Amorphous Polylactide Exposed to UV Light
Article dans une revue avec comité de lecture
Author
Date
2022-07Journal
Macromolecular Chemistry and Physics,Abstract
The degradation of polylactide (PLA) under UV exposure is investigated in terms of cooperativity and kinetic fragility at the glass transition. In the first part, possibly coexisting degradation mechanisms are evoked from the interpretation of the infrared spectroscopy analyses. Furthermore, the reduction of PLA chain length, owing to photolytic scissions predominant over local crosslinks, is assessed from chromatography, and confirmed by the shift of the glass transition temperature toward lower temperature. Modulated temperature thermogravimetric analysis (MT-TGA) also shows that the activation energy needed to initiate thermal degradation falls after UV exposure. In the second part, the impact of UV-induced degradation on the cooperative rearranging region (CRR) size and the kinetic fragility, respectively, calculated thanks to calorimetric and dielectric measurements, is discussed. Despite the assumed concomitance of several degradation mechanisms, it is observed that the glass transition, the kinetic fragility, and the CRR size decrease together with the exposure time. Moreover, it is found that the data align well on another trend depicting the change in the relaxation properties caused by plasticization of PLA. Thus, the variations of segmental relaxation properties caused by UV may be related to the increase of free volume linked to the damaging of the PLA structure.
Files in this item
- Name:
- PIMM_MCP_2022_RICHAUD.pdf
- Size:
- 1.950Mb
- Format:
- Description:
- Segmental Relaxation Dynamics ...
- Embargoed until:
- 2023-01-07
Related items
Showing items related by title, author, creator and subject.
-
Article dans une revue avec comité de lectureARAUJO, Steven; DELPOUVE, Nicolas; DHÔTEL, Alexandre; DOMENEK, Sandra; GUINAULT, Alain; DELBREILH, Laurent; DARGENT, Eric (ACS Publications, 2018)The kinetic fragility of a glass-forming liquid is an important parameter to describe its molecular mobility. In most polymers, the kinetic fragility index obtained from the glassy state by thermally stimulated depolarization ...
-
Article dans une revue avec comité de lectureARAUJO, Steven; DELPOUVE, Nicolas; DOMENEK, Sandra; GUINAULT, Alain; GOLOVCHAK, Roman; SZATANIK, Roman; INGRAM, Adam; FAUCHARD, Cyrille; DELBREILH, Laurent; DARGENT, Eric (American Chemical Society, 2019)The experimental evidence of the increase of activation energy associated with the super Arrhenius behavior governing amorphous polylactide by free volume variations has been obtained through a combination of calorimetric, ...
-
Article dans une revue avec comité de lectureVAROL, N.; DELPOUVE, Nicolas; ARAUJO, Steven; DOMENEK, Sandra; GUINAULT, Alain; GOLOVCHAK, Roman; INGRAM, A.; DELBREILH, Laurent; DARGENT, Eric (Elsevier, 2020)Plasticization of amorphous polylactide shifts the glass transition and extends its temperature range of crystallization to lower temperatures. In this work, we focus on how low−temperature crystallization impacts the ...
-
Article dans une revue avec comité de lectureOUMNAS, Sanaa; QUELENNEC, Blandine; RICHAUD, Emmanuel; DUTHOIT, Alexis; DELPOUVE, Nicolas; DELBREILH, Laurent (Wiley, 2023-02)In this work, epoxy networks used for civil engineering constructions are aged at ambient temperature, and the impact of the early stages of aging on mechanical properties is analyzed. It is observed that Young's modulus ...
-
Article dans une revue avec comité de lectureDELANNOY, Romain; QUELENNEC, Blandine; TOGNETTI, Vincent; DELBREILH, Laurent; DELPOUVE, Nicolas; RICHAUD, Emmanuel (2023)Four epoxy-amine networks were characterized by Dynamical Mechanical Analysis (DMA) and by Dielectric Relaxation Spectroscopy (DRS). The epoxy-amine networks were cured with DGEBA and four aliphatic amine hardeners: three ...