Full Text Available
Note: Clicking the button above will open the full text document at the original institutional repository in a new window.
Environmental and thermal aging studies on plastics and biopolymers : changes in mechanical properties and emissions of volatile organic compounds (VOCs)
Dissertation (MSc (Chemical Technology))--University of Pretoria, 2024.
Saved in:
| Other Authors: | |
|---|---|
| Format: | Thesis |
| Language: | English |
| Published: |
University of Pretoria
2025
|
| Tags: |
No Tags, Be the first to tag this record!
|
| _version_ | 1867613655507402752 |
|---|---|
| access_status_str | Open Access |
| author2 | Jacob John, Maya |
| author_browse | Jacob John, Maya |
| author_facet | Jacob John, Maya |
| collection | Thesis |
| dc_rights_str_mv | © 2023 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. |
| description | Dissertation (MSc (Chemical Technology))--University of Pretoria, 2024. |
| format | Thesis |
| id | oai:repository.up.ac.za:2263/101394 |
| institution | University of Pretoria (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:39:35.842Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UPSpace — University of Pretoria Institutional Repository |
| publishDate | 2025 |
| publishDateRange | 2025 |
| publishDateSort | 2025 |
| publisher | University of Pretoria |
| publisherStr | University of Pretoria |
| record_format | dspace |
| source_str | UPSpace — University of Pretoria Institutional Repository |
| spelling | oai:repository.up.ac.za:2263/101394 Environmental and thermal aging studies on plastics and biopolymers : changes in mechanical properties and emissions of volatile organic compounds (VOCs) Jacob John, Maya u22022776@tuks.co.za Tichapondwa, Shepherd Masimba Nzimande, Monwabisi Cyril Dissertation (MSc (Chemical Technology))--University of Pretoria, 2024. Plastics, especially biopolymers, degrade in response to environmental conditions such as UV radiation, heat, and moisture, resulting in surface changes and decreased in mechanical properties. As biopolymers replace traditional plastics, evaluating their long-term environmental impact is critical. This study aims were to investigate the effects of extended environmental aging on the surface and mechanical properties and the emission of volatile organic compound of biopolymers, including polybutylene adipate terephthalate (PBAT), poly (lactic acid) (PLA), polybutylene succinate (PBS) and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH).Biopolymers samples were prepared by melting and compounding in a twin-screw extruder, followed by injection moulding into dumbbell-shaped specimens. The changes in the structural, chemical, thermal, and mechanical characteristics of the biopolymer before and after were investigated by FT-IR, TS, TG-FTIR and Py-GC/MS. The visual appearance of biopolymers after exposure to accelerated aging for 1000 hours was studies. Photo-oxidation led to the formation of chromophores and double bonds, leading to PBAT, PHBH and PBS change color from white to yellow. PLA, which was before transparent due to its amorphous structure, became opaque white because of UV-induced cold crystallization. After 1500 hours of aging, tensile strength in PBAT increased by 12%, while for PBS and PHBH tensile strength decreased by 72% and 12%, respectively. PLA showed the highest decrease after 1000 hours due to UV-induced photodegradation and hydrolysis. Strain at break decreased significantly in PBS (98%), PBAT (64%), and PHBH (60%) after 1500 hours. FTIR spectroscopy confirmed the presence of carbonyl groups in PBS, PLA, and PBAT by revealing C=O and C-O bond peaks at 1710 cm−1 and 1046-1100 cm−1, respectively. To evaluate the effect of photooxidation, the carbonyl index was measured using FTIR analysis, which effectively measures oxidative degradation. The carbonyl index of the biopolymers decreased with aging indicating a gradual decrease in oxidative breakdown. TG-FTIR of biopolymers showed the present of degradation products majorly oligomers, unsaturated carboxylic acids, CO2, CO, and H2O. VOCs analysis revealed that no toxic emissions such as benzene or toluene were emitted from the recycled plastics before and after aging. The study showed that the highest concentration of VOCs was 3-formyl-benzoic acid in PBAT, 2-butenoic acid in PHBH, 2,5-furandione in PBS, and 1,4-dioxane-2,5-dione in PLA. The absence of harmful substances indicates that emissions are within acceptable levels, showing Py-GC/MS's efficiency in monitoring environmental safety. Department of Science and Innovation, South Africa, Waste RDI program, Grant Number: CSIR/BEI/WRIU/2021/047 Chemical Engineering MSc (Chemical Technology) Unrestricted Faculty of Engineering, Built Environment and Information Technology SDG-04: Quality education SDG-06: Clean water and sanitation SDG-07: Affordable and clean energy SDG-08: Decent work and economic growth 2025-03-07T13:35:21Z 2025-03-07T13:35:21Z 2025-04 2024-07 Dissertation * A2025 http://hdl.handle.net/2263/101394 https://doi.org/10.25403/UPresearchdata.28553669 en © 2023 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. application/pdf University of Pretoria |
| spellingShingle | Environmental and thermal aging studies on plastics and biopolymers : changes in mechanical properties and emissions of volatile organic compounds (VOCs) |
| title | Environmental and thermal aging studies on plastics and biopolymers : changes in mechanical properties and emissions of volatile organic compounds (VOCs) |
| title_full | Environmental and thermal aging studies on plastics and biopolymers : changes in mechanical properties and emissions of volatile organic compounds (VOCs) |
| title_fullStr | Environmental and thermal aging studies on plastics and biopolymers : changes in mechanical properties and emissions of volatile organic compounds (VOCs) |
| title_full_unstemmed | Environmental and thermal aging studies on plastics and biopolymers : changes in mechanical properties and emissions of volatile organic compounds (VOCs) |
| title_short | Environmental and thermal aging studies on plastics and biopolymers : changes in mechanical properties and emissions of volatile organic compounds (VOCs) |
| title_sort | environmental and thermal aging studies on plastics and biopolymers changes in mechanical properties and emissions of volatile organic compounds vocs |
| url | http://hdl.handle.net/2263/101394 https://doi.org/10.25403/UPresearchdata.28553669 |