$Preparation Of Low Molecular Weight Natural Rubber Via Photooxidation In Latex State$

Preparation Of Low Molecular Weight Natural Rubber Via Photooxidation In Latex State

Ultraviolet (UV) light has been used to degrade organic matters, including natural rubber (NR) which was commonly carried out in an organic solvent. The aim of this work is to prepare liquid natural rubber (LNR) using a photodegradation method in latex state, hence to characterize its physical and c...

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Main Author:	Ibrahim, Suhawati
Format:	Thesis
Language:	English
Published:	2020
Subjects:	T Technology
Online Access:	http://eprints.usm.my/47575/1/Preparation%20Of%20Low%20Molecular%20Weight%20Natural%20Rubber%20Via%20Photooxidation%20In%20Latex%20State.pdf
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spelling	my-usm-ep.475752021-11-17T03:42:09Z Preparation Of Low Molecular Weight Natural Rubber Via Photooxidation In Latex State 2020-07-01 Ibrahim, Suhawati T Technology TA401-492 Materials of engineering and construction. Mechanics of materials Ultraviolet (UV) light has been used to degrade organic matters, including natural rubber (NR) which was commonly carried out in an organic solvent. The aim of this work is to prepare liquid natural rubber (LNR) using a photodegradation method in latex state, hence to characterize its physical and chemical properties. The efficiency of photodegradation was determined by the molecular weight reduction and gel content of the LNR obtained. The molecular structure of LNR was determined by Fourier Transform Infrared (FTIR) and Nuclear Magnetic Resonance (NMR). While, Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) were used to determine the change in morphology of latex particles. Reaction parameters such as UV radiation, temperature, hydrogen peroxide, reaction time, dry rubber content (DRC) and stabilizers showed synergistic effect and influenced the reaction’s efficiency. Anionic surfactant (SDS) provided better stability to NR latex compared to non-ionic surfactant (Teric). The zeta potential of NR latex was increased during the photodegradation, provided by the negatively charge of fatty acid. Phosphate that represent fatty acid amount was increased in latex serum due to the decomposition of phospholipid upon exposure to the UV and oxidizing agent. Titanium dioxide (TiO2) anatase nanocrystals was prepared via the sol-gel method. The dispersed TiO2 in NR latex showed catalytic effect on the photodegradation reaction. The presence of methylene blue as photosensitizer during photodegradation lowered molecular weight of LNR. The cleavage of NR chains during photodegradation occurred at C=CH and CH2-CH2 bonds. The molecular structure of LNRs were similar to that the NR, but hydroxyl and carbonyl groups on its chain increased. These functional groups were formed as a result of chain cleavage of NR. Photodegradation of epoxidized natural rubber (ENR50) latex showed similar reaction to the NR latex without affecting the mole percentage of epoxy group. However, the presence of TiO2 during the reaction induced for the ring opening of epoxy group to hydroxyls. 2020-07 Thesis http://eprints.usm.my/47575/ http://eprints.usm.my/47575/1/Preparation%20Of%20Low%20Molecular%20Weight%20Natural%20Rubber%20Via%20Photooxidation%20In%20Latex%20State.pdf application/pdf en public phd doctoral Universiti Sains Malaysia Pusat Pengajian Kejuruteraan Bahan & Sumber Mineral
institution	Universiti Sains Malaysia
collection	USM Institutional Repository
language	English
topic	T Technology T Technology
spellingShingle	T Technology T Technology Ibrahim, Suhawati Preparation Of Low Molecular Weight Natural Rubber Via Photooxidation In Latex State
description	Ultraviolet (UV) light has been used to degrade organic matters, including natural rubber (NR) which was commonly carried out in an organic solvent. The aim of this work is to prepare liquid natural rubber (LNR) using a photodegradation method in latex state, hence to characterize its physical and chemical properties. The efficiency of photodegradation was determined by the molecular weight reduction and gel content of the LNR obtained. The molecular structure of LNR was determined by Fourier Transform Infrared (FTIR) and Nuclear Magnetic Resonance (NMR). While, Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) were used to determine the change in morphology of latex particles. Reaction parameters such as UV radiation, temperature, hydrogen peroxide, reaction time, dry rubber content (DRC) and stabilizers showed synergistic effect and influenced the reaction’s efficiency. Anionic surfactant (SDS) provided better stability to NR latex compared to non-ionic surfactant (Teric). The zeta potential of NR latex was increased during the photodegradation, provided by the negatively charge of fatty acid. Phosphate that represent fatty acid amount was increased in latex serum due to the decomposition of phospholipid upon exposure to the UV and oxidizing agent. Titanium dioxide (TiO2) anatase nanocrystals was prepared via the sol-gel method. The dispersed TiO2 in NR latex showed catalytic effect on the photodegradation reaction. The presence of methylene blue as photosensitizer during photodegradation lowered molecular weight of LNR. The cleavage of NR chains during photodegradation occurred at C=CH and CH2-CH2 bonds. The molecular structure of LNRs were similar to that the NR, but hydroxyl and carbonyl groups on its chain increased. These functional groups were formed as a result of chain cleavage of NR. Photodegradation of epoxidized natural rubber (ENR50) latex showed similar reaction to the NR latex without affecting the mole percentage of epoxy group. However, the presence of TiO2 during the reaction induced for the ring opening of epoxy group to hydroxyls.
format	Thesis
qualification_name	Doctor of Philosophy (PhD.)
qualification_level	Doctorate
author	Ibrahim, Suhawati
author_facet	Ibrahim, Suhawati
author_sort	Ibrahim, Suhawati
title	Preparation Of Low Molecular Weight Natural Rubber Via Photooxidation In Latex State
title_short	Preparation Of Low Molecular Weight Natural Rubber Via Photooxidation In Latex State
title_full	Preparation Of Low Molecular Weight Natural Rubber Via Photooxidation In Latex State
title_fullStr	Preparation Of Low Molecular Weight Natural Rubber Via Photooxidation In Latex State
title_full_unstemmed	Preparation Of Low Molecular Weight Natural Rubber Via Photooxidation In Latex State
title_sort	preparation of low molecular weight natural rubber via photooxidation in latex state
granting_institution	Universiti Sains Malaysia
granting_department	Pusat Pengajian Kejuruteraan Bahan & Sumber Mineral
publishDate	2020
url	http://eprints.usm.my/47575/1/Preparation%20Of%20Low%20Molecular%20Weight%20Natural%20Rubber%20Via%20Photooxidation%20In%20Latex%20State.pdf
_version_	1747821804358991872

Preparation Of Low Molecular Weight Natural Rubber Via Photooxidation In Latex State

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