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Synthesis of Biobased Polyethers, Polyesters and Polyamides from Canola Oil Derived Monomers Using Microwave Irradiation
- Author / Creator
- Ahmadi, Reza
Polymers are essential in modern life’s sustainable growth with their diverse applications in packaging, construction, automotive, electronic industries, etc. Nowadays, polymer industry mainly depends on petroleum resources as feedstock and energy source. Increased environmental concerns and limited petroleum resources have impelled industry and researchers to look for renewable feedstocks and alternative methods of polymer synthesis. Plant oils have been considered as prospective feedstocks for the polymer industry due to their worldwide availability and structural similarity to petroleum resources. Microwave irradiation has also emerged as an alternative heating technique for polymer synthesis. This thesis investigated the synthesis and characterization of different polymers from canola oil-derived monomers under conventional heating and microwave irradiation.
In the first study, α-olefin (1-decene) was polymerized to biopolyethers after chemical modification. 1-decene was first converted to 1,2-epoxydecane using m-chloroperoxybenzoic acid, and then subjected to ring-opening polymerization (ROP). Microwave-assisted epoxidation of 1-decene was optimized at 5 min (67% yield), whereas, the conventional epoxidation was completed at 60 min (> 93% yield). ROP of 1,2-epoxydecane was carried out using modified methyl aluminoxane (MMAO) catalyst and resulted in the production of high-molecular weight biopolyethers (M ̅_w> 2 × 106 g/ mol). A three-factor, three-level Box-Behnken response surface design was employed to investigate the effect of process parameters such as time, temperature, and the solvent-monomer ratio on the yield of microwave ring-opening polymerization. Although elevating all test parameters enhanced polymerization yield, the temperature was more effective than other variables. The optimal predicted parameters of reaction time 9.97 min, temperature 99.69 °C, and solvent to monomer ratio of 5.27:5 resulted in the maximum polyether yield of 82.51%. The microwave-assisted ROP improved the polymerization yield (about 9.8%) and reduced the required amount of solvent by 30% compared to the conventional reaction. Thermal stability of biopolyethers produced under both heating methods was comparable, with the melting temperature of 89°C and decomposition temperature in the range of 325- 418 °C. The microwave irradiation yielded a biopolyether with lower glass transition (Tg) compared to the conventional heating, which was explained by the microwave’s effect on the polymer’s tacticity.
The second and third studies investigated synthesis and characterization of two long-chain, unsaturated polyamides, PA (DMOD-PXDA) and PA (DMOD-DETA), from dimethyl 9-octadecenedioate (DMOD) and two different amines (p-Xylylenediamine and diethylenetriamine) under conventional heating and microwave irradiation. The melting temperature of polyamides was around 190 °C with higher values for the conventionally polycondensed ones. Polyamides’ films were also prepared, and their characteristics were evaluated. PA (DMOD-PXDA) films had tensile strengths of about 20 Mpa. The percent elongation at break of the film from conventionally polymerized PA (DMOD-PXDA) was 3 times higher than its microwave polymerized counterpart. Regarding PA (DMOD-DETA) films, the film from conventionally polymerized PA (DMOD-DETA) showed higher tensile strength but lower percent elongation at break compared to its microwave counterpart. In the last study, a one-pot synthesis approach for producing a novel long-chain, unsaturated bio-based polyester using three canola oil-based monomers including dimethyl 9-octadecenedioate, its acid (9-octadecenedioic acid), and 1,2-epoxydecane was developed. The one-pot polymerization was carried out in two sequential steps, the addition of 9-octadecenedioic acid to 1,2-epoxydecane followed by polycondensation of the resulting biodiol (bis(2-hydroxydecyl) octadec-9-enedioate (BHOD)) with dimethyl 9-octadecenedioate. The first step of the reaction (acid-epoxy addition) was successfully performed without using any solvent or catalysts under both conventional and microwave heating. The microwave acid-epoxy addition resulted in a 6-fold decrease in reaction time (30 min) compared to conventional heating (3 hrs). The second step to produce the long-chain, unsaturated biopolyester was carried out using SnCl2 catalyst in a solvent-free media and a high vacuum under conventional heating. Interestingly, the synthesized biopolyester was a thermally stable long-chain polymer with a decomposition temperature of > 329 °C and a melting temperature of > 276 °C. The biopolyester’s thermal properties were comparable to the commonly used commercial polyesters such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT).
Overall, this work developed synthesis approaches and rapid processes for synthesizing high molecular weight biopolyethers and long-chain biopolyester and polyamides with unsaturated motifs which are highly attractive from both industrial and academic points of view.
- Graduation date
- Spring 2021
- Type of Item
- Doctor of Philosophy
- This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.