Optimisation of waste vegetable oil-based thermoset polymers (original) (raw)
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Vegetable oil-derived epoxy monomers and polymer blends: A comparative study with review
Express Polymer Letters
Glycidyl esters of epoxidized fatty acids derived from soybean oil (EGS) and linseed oil (EGL) have been synthesized to have higher oxirane content, more reactivity and lower viscosity than epoxidized soybean oil (ESO) or epoxidized linseed oil (ELO). The EGS and ESO, for comparison, were used neat and in blends with diglycidyl ether of bisphenol A (DGEBA). Thermosetting resins were fabricated with the epoxy monomers and either BF 3 catalyst or anhydride. The curing behaviors, glass transition temperatures, crosslink densities and mechanical properties were tested. The results indicated that polymer glass transition temperatures were mostly a function of oxirane content with additional influence of glycidyl versus internal oxirane reactivity, pendant chain content, and chemical structure and presence of saturated components. EGS provided better compatibility with DGEBA, improved intermolecular crosslinking and glass transition temperature, and yielded mechanically stronger polymerized materials than materials obtained using ESO. Other benefits of the EGS resin blend systems were significantly reduced viscosities compared to either DGEBA or ESO-blended DGEBA counterparts. Therefore, EGS that is derived from renewable sources has improved potential for fabrication of structural and structurally complex epoxy composites, e.g., by vacuum-assisted resin transfer molding.
Epoxidized Vegetable Oils for Thermosetting Resins and Their Potential Applications
Springer series on polymer and composite materials, 2017
In the recent decades, bio-based polymers have gained increasing interest, especially for composite materials. These polymers and their respective monomers are derived from renewable resources, being thermoplastics or thermosetting resins which are biodegradable or non-biodegradable. Thermosettings are strong, rigid polymer materials and cannot be easily processed by melting after their hardening. At present, thermosetting resins are obtained using highly toxic and volatile petrochemicals, which require human and environmental safety monitoring. Considering the wide range of diverse renewable monomers available, vegetable oils (VOs) are especially well-suited when it comes to the synthesis of thermosetting resins due to their carbon-carbon double bonds, highly desirable for this type of application as these unsaturated bonds can be chemically modified in order to increase reactivity toward further polymerization. Thus, epoxidation, which consists of introducing a single oxygen atom to each non-saturated bond to yield in an epoxidic cycle, is a simple, effective method to modify these VOs. The resulted thermosetting resins exhibit improved toughness and environmental-friendly behavior. VOs, especially soybean oil which is abundant and cheap, are typically mixtures of unsaturated fatty acids with numerous bonds that can be easily converted into the more reactive oxirane rings through the reaction with peracids or
Epoxidized Glycidyl Ester of Soybean Oil as Reactive Diluent for Epoxy Resin
Epoxidized glycidyl esters of soybean oil (EGS) have been synthesized and used as reactive diluents for partial replacement of a commercial, bisphenol A-based epoxy resin (DGEBA). The EGS merits include a higher epoxy content and lower viscosity than the epoxidized triglyceride soybean oil (ESO). Thermosetting resins were fabricated from DGEBA systems blended with various amounts of EGS and ESO, using 4-methyl-1,2-cyclohexanedicarboxylic anhydride as a curing agent and 2-ethyl-4-methylimidazole as catalyst. The curing behavior and glass transition were monitored by differential scanning calorimetry (DSC), the performance of thermosetting resins was studied by measurement of thermal stability and flexural properties. The results indicate that EGS resins provide better compatibility, intermolecular crosslinking, and yield materials that are stronger than materials obtained using ESO. However, the EGS resin systems significantly reduce viscosity compared to either pure DGEBA or ESO-ble...
Polymer Engineering & Science, 2013
The present work was aimed at studying the effects of incorporation of epoxidized soybean oil (ESO) in a standard bisphenol A-type epoxy resin (EP) cured by anhydride hardener. The EP/ESO ratio was set for 100/0, 75/25, 50/50, 25/75 and 0/100 (wt.%/wt.%). The investigations performed covered the curing, rheology (gelling), thermomechanical (TMA) and thermogravimetric analysis (TGA) of the EP/ESO compositions. The results showed that the dilution of EP with ESO was accompanied with marked changes in the curing, gelling behavior and final properties. Differential scanning calorimetry (DSC) revealed that the crosslinking of EP/ESO≥50/50 occurred in two steps. This has been considered for the cure schedule set. The gel time of EP/ESO, determined at T=100, 120, 140 o C, respectively, increased with increasing ESO content. The activation energy of gelling increased with increasing ESO content. The glass transition temperature decreased with increasing ESO content of the transparent samples. According to TMA the coefficient of thermal expansion in the glassy state increased with increasing ESO content but was independent of the latter in the rubbery stage. TGA indicated that with increasing ESO content the thermal degradation started earlier and the char yield decreased. The Ozawa, Flynn and Wall (OFW) approach was adapted to TGA tests to calculate
Journal of Applied Polymer Science, 2021
Major limitation for use of epoxy thermosets in engineering applications is its sudden brittle failure. In the present study dipropylene glycol dibenzoate (DPGDB) based plasticizer is used to modify diglycidyl ether of bisphenol A (DEGEBA) based epoxy resin system via simple blending technique. Bio-based epoxidized linseed oil was also used to modify epoxy resin system and compared with DPGDB modified resin. For DPGDB modified resin storage modulus and loss modulus of the epoxy system modified with 10% plasticizer increased by 7.54% and 12.24%, respectively. The primary mechanism responsible for such behavior is improved crosslinking density. With 5% plasticizer loading, flexural strength increased by 21%. There was an improvement of 312.74% in strain at failure for 10% plasticizer loading, while preserving its mechanical strength. It was found that DPGDB based modification was better than epoxidized linseed oil modification.
Polymers for Advanced Technologies, 2017
In the current work, renewable resourced toughened epoxy blend has been developed using epoxidized linseed oil (ELO) and bio-based crosslinker. Epoxidation of linseed oil was confirmed through FTIR and 1 H NMR spectra. The ELO bio-resin was blended at different compositions (10, 20, and 30 phr) with a petroleum-based epoxy (DGEBA) as reactive diluent to reduce the viscosity for better processibility and cured with cardanol-derived phenalkamine to overcome the brittleness. The flow behavior of the neat epoxy and modified bio-epoxy resin blend systems was analyzed by Cross model at low and high shear rates. The tensile and impact behavior studies revealed that the toughened bio-epoxy blend with 20 to 30 phr of ELO showed moderate stiffness with much higher elongation at break 7% to 13%. Incorporation of higher amount of ELO (20 to 30 phr) increases enthalpy of curing without affecting peak temperature of curing. The thermal degradation behavior of the ELO based blends exhibits similar trend as neat epoxy. The higher intensity or broadened loss tangent curve of bio-epoxy blends revealed higher damping ability. FE-SEM analysis showed a rough and rippled surface of bio-based epoxy blends ensuring effective toughening. Reduced viscosity of resin due to maximum possible incorporation of bio-resin and use of phenalkamine as curing agent leads to an eco-friendly toughened epoxy and can be useful for specific coating and structural application.