The increasing concern about environment preservation and the problematic related to petroleum depletion have prompted the research ever more into the development and study of new materials from renewable resources. In this context, vegetable oils with a trygliceride structure and, in particular, linseed oil have gained a relevant interest given their intrinsic ability to be functionalized, for example, by an opportune epoxidization process to obtain so-called epoxidized linseed oils (ELOs). In this research, two commercial ELOs, PlastHall ELO (Hallstar, EEW=175.82, %O=9.6) and Lankroflex L (Akros Chemicals, EEW=180, %O=8.9), were crosslinked in presence of cis-1,2,3,6 tetrahydrophthalic anhydride (THPA) as hardener and 1% by weight of 1-methyl imidazole (MI) as the catalyst, according to a previously optimized process taking a traditional bifunctional epoxy resin, cured under the same conditions, as the reference material. All materials were analyzed by calorimetric and thermogravimetric tests, static and dynamic flexural measurements, indirect evaluations of the heat distortion temperature according to the ASTM E2902 Normative and, finally, by water and toluene absorption behavior at room temperature comparing mechanical properties of conditioned samples at different times. Experimental results demonstrated that the applied curing process allowed the achievement of an acceptable degree of crosslinking for bioresins, even if slightly lower than that shown by the conventional epoxy system. In terms of mechanical properties, although bioresins showed inferior performances with respect to the reference material, PlastHall ELO based resin is characterized by higher flexural parameters with respect to Lankroflex L based one. Finally, regarding the absorption tests, the intrinsic chemical structure of the two bio-based epoxy resins induced a different behavior depending on the polarity of used solvents. In general, within 258 h, given that bioresins always absorbed more than the reference one, the solvent uptake at room temperature amounted to about 2% and 30% by weight for water and toluene, respectively. Moreover, while PlastHall ELO resin exhibited a major attitude to include water than Lankroflex L based material, the reverse was noted in case of toluene absorption tests.
Bioresins based on epoxidized linseed oils: preparation and characterization
P Russo
2015
Abstract
The increasing concern about environment preservation and the problematic related to petroleum depletion have prompted the research ever more into the development and study of new materials from renewable resources. In this context, vegetable oils with a trygliceride structure and, in particular, linseed oil have gained a relevant interest given their intrinsic ability to be functionalized, for example, by an opportune epoxidization process to obtain so-called epoxidized linseed oils (ELOs). In this research, two commercial ELOs, PlastHall ELO (Hallstar, EEW=175.82, %O=9.6) and Lankroflex L (Akros Chemicals, EEW=180, %O=8.9), were crosslinked in presence of cis-1,2,3,6 tetrahydrophthalic anhydride (THPA) as hardener and 1% by weight of 1-methyl imidazole (MI) as the catalyst, according to a previously optimized process taking a traditional bifunctional epoxy resin, cured under the same conditions, as the reference material. All materials were analyzed by calorimetric and thermogravimetric tests, static and dynamic flexural measurements, indirect evaluations of the heat distortion temperature according to the ASTM E2902 Normative and, finally, by water and toluene absorption behavior at room temperature comparing mechanical properties of conditioned samples at different times. Experimental results demonstrated that the applied curing process allowed the achievement of an acceptable degree of crosslinking for bioresins, even if slightly lower than that shown by the conventional epoxy system. In terms of mechanical properties, although bioresins showed inferior performances with respect to the reference material, PlastHall ELO based resin is characterized by higher flexural parameters with respect to Lankroflex L based one. Finally, regarding the absorption tests, the intrinsic chemical structure of the two bio-based epoxy resins induced a different behavior depending on the polarity of used solvents. In general, within 258 h, given that bioresins always absorbed more than the reference one, the solvent uptake at room temperature amounted to about 2% and 30% by weight for water and toluene, respectively. Moreover, while PlastHall ELO resin exhibited a major attitude to include water than Lankroflex L based material, the reverse was noted in case of toluene absorption tests.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
