Kinetic Study of the Thermal and Thermo-Oxidative Degradations of Polystyrene Reinforced with Multiple-Cages POSS.

Ignazio Blanco,Claudio Tosto,Gianluca Cicala,Francesco Agatino Bottino

doi:10.3390/polym12112742

Ignazio Blanco, Claudio Tosto + Show 2 more

Open Access

https://doi.org/10.3390/polym12112742

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Journal: Polymers	Publication Date: Nov 19, 2020
Citations: 6	License type: CC BY 4.0

Affiliation: University of Catania

Abstract

A comprehensive kinetics degradation study is carried out on novel multiple cages polyhedral oligomeric silsesquioxane (POSS)/polystyrene (PS) composites at 5% (w/w) of POSS to assess their thermal behavior with respect to the control PS and other similar POSS/PS systems studied in the past. The composites are synthesized by in situ polymerization of styrene in the presence of POSSs and characterized by 1H-NMR. The characteristics of thermal parameters are determined using kinetics literature methods, such as those developed by Kissinger and Flynn, Wall, and Ozawa (FWO), and discussed and compared with each other and with those obtained in the past for similar POSS/PS composites. A good improvement in the thermal stability with respect to neat polymer is found, but not with respect to those obtained in the past for polystyrene reinforced with single- or double-POSS cages. This behavior is attributed to the greater steric hindrance of the three-cages POSS compared with those of single- or double-cage POSS molecules.

Highlights

Despite the pressing media campaign regarding the persistence of plastic in the environment, researchers are well aware that typical polymers are not indefinitely stable
During the in situ polymerization, we observed a slight increase in the polyhedral oligomeric silsesquioxane (POSS) content in the During the in situ polymerization, we observed a slight increase in the POSS content in the obtained composites with respect to the initial mixture ratio (5% w/w) due to the formation of obtained composites with respect to the initial mixture ratio (5% w/w) due to the formation of methanol methanol soluble oligomers of PS
The design and preparation of new PS composites reinforced with triple-cage POSS, uniquely functionalized with isobutyl and cyclopentyl groups, were carried out to verify if the presence of a higher number of POSS cages in the same molecule, dispersed in the matrix, leads to a further increase of material stabilization

Summary

Introduction

Despite the pressing media campaign regarding the persistence of plastic in the environment, researchers are well aware that typical polymers are not indefinitely stable. Academic research has been devoted to enhancing the physical properties of polymers by adding low-molecular-weight substances such as plasticizers, stabilizers, and anti-blocking agents [15,16] or to modifying their structures and verifying the effects of these modifications over the lifetime of the material under artificial accelerated conditions [17,18,19] In this context, our research group at the University of Catania, in collaboration with eminent researchers in the field, tested the stabilization of different polymers, synthetics or naturals, such as polyethersulfone (PES), ethylene propylene diene monomer (EPDM), polyethylene oxide (PEO), and chitosan by the incorporation of polyhedral oligomeric silsesquioxanes (POSS). The calculated parameters, namely temperature at 5% mass loss (T5% ) and apparent activation energy (Ea ) of degradation, were compared with each other and with those of the control PS to evaluate the differences in thermal behavior, if present

Materials

Thermogravimetric

Results and Discussion

Conclusions

A Comprehensive Treatment