Cationic polymerization and physicochemical properties of a biobased epoxy resin initiated by thermally latent catalysts

The cationic polymerization and physicochemical properties of a biobased epoxy resin, epoxidized castor oil (ECO), initiated by N-benzylpyrazinium hexafluoroantimonate (BPH) and N-benzylquinoxalinium hexafluoroantimonate (BQH) as thermally latent catalysts were studied. As a result, BPH and BQH show an activity at different temperatures in the present systems. The cured ECO/BPH system showed a higher glass transition temperature, a lower coefficient of thermal expansion, and higher thermal stability factors than those of the ECO/BQH system. On the other hand, the mechanical properties of the ECO/BQH system were higher than those of the ECO/BPH system. These have been attributed to the differences in crosslinking level of cured resins, which were induced by the different activity of the latent catalysts.     

Bio‐based nanocomposites composed of photo‐cured epoxidized soybean oil and supramolecular hydroxystearic acid nanofibers

A mixture of epoxidized soybean oil (ESO), (R)‐12‐hydroxystrearic acid (HSA) and a photoinitiator for cationic polymerization in the ESO/HSA weight ratio 10/1 was heated to 100 °C and gradually cooled to room temperature to give bio‐based gelatinous material. The photo‐curing of the gel afforded a nanocomposite composed of crosslinked ESO and supramolecular HSA nanofibers. The transmission electron microscopy observation of the photo‐cured ESO/HSA revealed that dendritic clusters of HSA nanofibers are formed in the crosslinked ESO matrix. In the differential scanning calorimetry chart of the ESO/HSA, a thermal transition from the mesophase composed of supramolecular nanofibers to isotropic state was observed at 67 °C (ΔH = 22.6 J/g‐HSA), while the T_m of crystalline HSA is 77.7 °C (ΔH_m = 159 J/g‐HSA). Tensile strength at 20 °C of the ESO‐HSA was ～80% higher than that of photo‐cured ESO without HSA. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 669–673, 2009     

Improved hydrolytic stability of poly(dl-lactide) with epoxidized soybean oil

The multi-arm star polymer (ESOPLA) was obtained by ring-opening polymerization of dl-lactide using multifunctional epoxidized soybean oil (ESO) as an initiator in the presence of a stannous actuate (SnOct₂) catalyst. Gel permeation chromatography with multi-angle laser light scattering (GPC-MALLS), FTIR, ¹H NMR, thermal analysis and in vitro degradation were used to qualitatively characterize the synthesized polymers. The results revealed that ESO plays an important role in increasing the molecular weight, polymerization rate and monomer conversion rate. Degradation analysis demonstrated that the decrease in molecular weight and the weight loss ratio of the star-shaped ESOPLA were lower than that of linear poly(dl-lactide) (PDLLA). The surface topography of pre- and post-degradation materials was characterized by scanning electron microscopy (SEM). These SEM images showed that the linear PDLLA films underwent water erosion more readily than the star-shaped polymer films.     

“Green polyethylene” and curauá cellulose nanocrystal based nanocomposites: Effect of vegetable oils as coupling agent and processing technique

Cellulose nanocrystals (CNC) were prepared from curauá fibers via acid hydrolysis, and used as reinforcing phase for high‐density biopolyethylene (HDBPE) or green polyethylene. Castor oil (CO), epoxidized soybean oil (ESO) and epoxidized linseed oil (ELO) were chosen as compatibilizers for this study. Nanocomposites reinforced with CNC (3, 6, and 9 wt %) were processed by extrusion, using CO (3, 6, and 9 wt %) to evaluate its action as CNC dispersing agent in the HDBPE matrix. From the results obtained for these films, the CNC and oil contents were set at 3 wt%. In addition to CO, ELO, and ESO were also used, and besides processing by extrusion, extrusion/hot‐pressing process was also considered, in order to compare the two processing techniques. The nanocomposites were characterized by microscopic, thermal, mechanical, and rheological analyses. The presence of oil leads to less opaque films and improved dispersion. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 1010–1019     

Synthesis and Photoinitiated Cationic Polymerization of Epoxidized Castor Oil and Its Derivatives

ABSTRACT

In this communication we describe the synthesis of epoxidized castor oil (ECO) as an interesting and inexpensive biorenewable monomer by an efficient and low cost epoxidation process. Also described are studies of the photoinitiated cationic polymerization of ECO using diaryliodonium salt photoinitiators. The influence of the structure and the concentration of the photoinitiator on the polymerization are reported. The ability of photosensitizers to accelerate the photopolymerization was also studied. Studies comparing the photopolymerization behavior of ECO with other commercially available epoxidized linseed and soybean oils and with other types of synthetic epoxy monomers were conducted. The excellent reactivity of ECO can be ascribed to the presence of both epoxy and hydroxyl groups in the molecule which permits this material to polymerize mainly by an activated monomer mechanism.

     

Development of completely bio‐based epoxy networks derived from epoxidized linseed and castor oil cured with citric acid

Bio‐based epoxy resins were synthesized from nonedible resources like linseed oil and castor oil. Both the oils were epoxidized through in situ method and characterized via Fourier transform infrared and ¹H‐NMR. These epoxidized oils were crosslinked with citric acid without using any catalyst and their properties compared with diglycidyl ether of bisphenol A‐epoxy. The tensile strength and modulus of epoxidized linseed oil (ELO) were found to be more than those of epoxidized castor oil (ECO)‐based network. However, elongation at break of ECO was significantly higher than that of both ELO and epoxy, which reveals its improved flexibility and toughened nature. Thermogravimetric analysis revealed that the thermal degradation of ELO‐based network is similar to that of petro‐based epoxy. Dynamic mechanical analysis revealed moderate storage modulus and broader loss tangent curve of bio‐based epoxies confirming superior damping properties. Bioepoxies exhibit nearly similar contact angle as epoxy and display good chemical resistant. The preparation method does not involve the use of any toxic catalyst and more hazardous solvents, thus being eco‐friendly.     

Plasticizing effects of epoxidized sun flower oil on biodegradable polylactide films: A comparative study

Polylactide (PLA) is one of the most promising materials among the renewable source-based biodegradable plastics. However, high inherent stiffness and brittleness of the pure PLA is often insufficient for wide range of engineering applications. One of the best ways to improve the processability, toughness and flexibility of PLA is to plasticize with epoxidized plant oils. In this work, epoxidized sun flower oil (ESFO) was incorporated into PLA matrix. The thermal, mechanical, biodegradation, optical transmission properties and fracture morphology of ESFO plasticized PLA were investigated to make a comparison with that of PLA plasticized by commercial epoxidized soya bean oil (ESO). Results show that a remarkable improvement of elongation at break was observed in the case of ESFO incorporated PLA. Although a slightly decrease the T _g of PLA was resulted from the plasticizing effects of ESFO, the thermal stability of the plasticized PLA was improved. On the other hand, the ESFO plasticized PLA showed a higher level of UV adsorption but a lower level of biodegradation ratio. After all, ESFO exhibited similar effects on the biodegradable PLA films to ESO, which is anticipated to be a good candidate for plasticizing biodegradable polymer materials.     

Castor oil modified by epoxidation,transesterification, and acrylation processes: Spectroscopic characteristics

In the present study, castor oil (CO) was modified by epoxidation, transesterification, and acrylation processes. In situ epoxidation method was used to prepare epoxidized castor oil (ECO) in acetic acid with hydrogen peroxide in the presence of Seralite SRC-120 catalyst. Transesterified epoxidized castor oil was synthesized from the reaction of methanol in the presence of sodium methoxide catalyst. The acrylated epoxidized castor oil was synthesized from the reaction of ECO with acrylic acid containing hydroquinone. Chemical structures of modified CO were analyzed by Fourier transform infrared spectroscopy and proton nuclear magnetic resonance spectra analysis.     

Effect of stearate preheating on the thermal stability of plasticized PVC compounds

Effect of preheating of stearates on the processing and post-processing thermal stability of poly(vinyl chloride) compounds, plasticized with di(2-ethylhexyl) phthalate (DEHP) and epoxidized soybean oil (ESO), using several ratios of calcium/zinc stearates and DEHP/ESO is reported. The compounds were prepared as follows: (1) dry-blending the compound components, (2) pelletizing the dry-blend and (3) extruding the pellets to obtain a ribbon geometry. Processing stability was determined by: (a) mechanical characterization and (b) visual color comparison of extruded samples. Post-processing thermal stability was followed by: (a) measurement of HCl release from heated pellets and (b) color changes in heated ribbon samples. From a practical point of view, the preheating has a negligible effect on the initial color of formulations; except for the case of formulations without both ESO and CaSt₂. However, the effect of the preheating on the post-processing thermal stability is strongly determined by the composition formulation.     

Thermal and mechanical properties of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) plasticized by biodegradable soybean oils

The effects of soybean oil (SO) and epoxidized soybean oil(ESO) as biodegradable plasticizers for poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) were studied using thermal and mechanical analyses. PHBV/SO and PHBV/ESO blends were prepared by evaporating solvent from blend solutions. The levels of additive in the blend varied from 5% to 30%. As a plasticizer for PHBV, ESO was more effective than SO in depression of the glass transition temperature as well as in increasing the elongation at break and the impact strength of the films with increasing levels of additive. Biodegradation of the plasticized PHBV films was carried out by accelerated compost method. The degradation rates of the blend films with SO or ESO were found to be faster than that of PHBV film. From the thermogravimetric analysis, it was found that the thermal reaction between the epoxide groups of ESO and PHBV fragments with carboxylic chain ends, occurred during the degradation of PHBV/ESO blends.     

4-Vinylbenzenesulfonic acid adduct of epoxidized soybean oil: Synthesis, free radical and ADMET polymerizations

In this work new radically polymerizable triglyceride based monomers were synthesized by the reaction of epoxidized methyl oleate (EMO) and epoxidized soybean oil (ESO) with 4-vinyl benzene sulfonic acid (4VBSA). The products are 1-(4-vinylbenzene sulfonyl)oxy-2-alkonols of epoxidized soybean oil (SESO) and 1-(4-vinylbenzene sulfonyl)oxy-2-alkonols of epoxidized methyl oleate (SEMO). These adducts were characterized by ¹H NMR, ¹³C NMR, IR and CHNS elemental analysis. SESO was found to contain, on the average, 2.47 4VBSA units per triglyceride. SESO was free radically polymerized and co-polymerized with styrene and the mechanical and thermal properties of the resulting thermosets were determined by DMA, DSC and TGA. SEMO was used as a model compound to determine the efficiency of metathesis catalysts for these fatty acid derivatives. The second generation Hoveyda–Grubbs catalyst was found to give best yields. ADMET polymerization of SESO with this catalyst with and without solvent gave ∼80% yield of a thermoset polymer. Polymers obtained by free radical route swelled in water at room temperature, and hydrolyzed in water at 60 °C.     

Carbonyldiimidazole‐accelerated efficient cure of epoxidized soybean oil with dicyandiamide

This study investigates the curing of epoxidized soybean oil (ESO) using dicyandiamide (DICY) and combinations of DICY with several accelerators as curing agents. The differential scanning calorimetry (DSC) results indicated that carbonyldiimidazole (CDI) is a highly efficient accelerator for the ESO‐DICY curing system. CDI accelerated ESO‐DICY curing system can gel within a short period of 13 min at 190 °C. The activation energies of the ESO‐DICY curing systems with and without CDI are 95 and 121 kJ mol^?1, respectively. Similar acceleration effect was observed in the ESO‐diglycidyl ether of biphenyl A (DGEBA) blending formulations. When the molar part of the glycidyl epoxy groups of DGEBA was equal to the internal epoxy groups of ESO in the mixture, gelation of the DICY curing system accelerated by CDI was achieved in 3 min at 160 °C. Furthermore, the DSC results with FTIR analysis suggest that the stoichiometric curing molar ratio was 3 ESO epoxy units per 1 DICY molecule. Two epoxy units reacted with DICY to give secondary alcohols, while the other one linked to the nitrile group. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 375–382     

Synthesis and application of phenolic resin internally toughened by chain extension polymer of epoxidized soybean oil

A novel epoxidized soybean oil (ESO) internally toughened phenolic resin(ESO-IT-PR) with both good toughness and excellent thermal stability was prepared as the matrix resin of copper clad laminate (CCL). FTIR was adopted to investigate the molecular structure of modified phenolic resins and SEM was used to observe the micro morphology of their impacted intersections. The properties of CCLs prepared with these modified phenolic resins were studied to determine the optimal process and investigate the toughening mechanism. The main modifying mechanism is the etherification reaction between phenol hydroxyl and ESO catalyzed by triethanolamine and the chain extension polymerization between ESO and multi-amine gives the long-chain ESO epoxy grafting on the phenolic resin prepolymer. when the ESO content is 30% and the curing agent content is 7%, the ESO toughened phenolic resin possesses optimal performance. The flexible ESO epoxy shows significant toughening effect and it crosslinks with the phenolic resin to form an internally toughened network, which is the key factor for improving the solderleaching resistance of CCL prepared with this modified phenolic resin. __________ Translated from Journal of South China University of Technology (Natural Science Edition), 2007, 35(7): 99–104 [译自: 华南理工大学学报(自然科学版)]     

Polystyrene‐modified novolac epoxy resin/clay nanocomposite: Synthesis,and characterization

A polystyrene‐modified epoxidized novolac resin/montmorillonite nanocomposite was fabricated and characterized successfully. For this purpose, novolac resin (NR) was epoxidized through the reaction of phenolic hydroxyl group with epichlorohydrin in super basic medium to produce epoxidized novolac resin (ENR). Afterward, a polystyrene was synthesized by atom transfer radical polymerization (ATRP) technique, and then brominated at the benzylic positions using N‐bromosuccinimide (NBS). The brominated polystyrene (PSt‐Br) was reacted with ethanolamine in basic medium in order to afford an amine‐functionalized polystyrene (PSt‐NH₂). An organo‐modified montmorillonite (O‐MMT) was synthesized through the treatment of MMT with hexadecyl trimethyl ammonium chloride salt. Finally, ENR‐PSt/MMT nanocomposite was fabricated through curing a mixture of ENR (70 wt.%) and O‐MMT (5 wt.%) with PSt‐NH₂ (25 wt.%). Transition electron microscopy (TEM) and powder X‐ray diffraction (XRD) analysis revealed that the fabricated nanocomposite has an exfoliated structure. Thermal property studies using thermogravimetric analysis (TGA) showed that the curing of ENR by PSt‐NH₂, as well as incorporation of a small amount of MMT have synergistic effect on the thermal stability of the ENR resin.     

Synthesis of graft polymers with poly(isoprene) as main chain by living anionic polymerization mechanism

The graft polymers [poly(isoprene)‐graft‐poly(styrene)] (PI‐g‐PS), [poly(isoprene)‐graft‐poly(isoprene)] (PI‐g‐PI), [poly(isoprene)‐graft‐(poly(isoprene)‐block‐poly(styrene))] PI‐g‐(PI‐b‐PS), and [poly(isoprene)‐graft‐(poly(styrene)‐block‐poly(isoprene))] PI‐g‐(PS‐b‐PI) with PI as main chain were synthesized through living anionic polymerization (LAP) mechanism and the efficient coupling reaction. First, the PI was synthesized by LAP mechanism and epoxidized in H₂O₂/HCOOH system for epoxidized PI (EPI). Then, the graft polymers with controlled molecular weight of main chain and side chains, and grafting ratios were obtained by coupling reaction between PI^?Li⁺, PS^?Li⁺, PS‐b‐PI^?Li⁺, or PI‐b‐PS^?Li⁺ macroanions and the epoxide on EPI. The target polymers and all intermediates were well characterized by SEC,¹H NMR, as well as their thermal properties were also evaluated by DSC. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Isothermal cure kinetics of epoxy/phenol‐novolac resin blend system initiated by cationic latent thermal catalyst

The investigation of the cure kinetics of a diglycidyl ether of bisphenol A (DGEBA)/phenol‐novolac blend system with different phenolic contents initiated by a cationic latent thermal catalyst [N‐benzylpyrazinium hexafluoroantimonate (BPH)] was performed by means of the analysis of isothermal experiments using a differential scanning calorimetry (DSC). Latent properties were investigated by measuring the conversion as a function of curing temperature using a dynamic DSC method. The results indicated that the BPH in this system for cure is a significant thermal latent initiator and has good latent thermal properties. The cure reaction of the blend system using BPH as a curing agent was strongly dependent on the cure temperature and proceeded through an autocatalytic kinetic mechanism that was accelerated by the hydroxyl group produced through the reaction between DGEBA and BPH. At a specific conversion region, once vitrification took place, the cure reaction of the epoxy/phenol‐novolac/BPH blend system was controlled by a diffusion‐control cure reaction rather than by an autocatalytic reaction. The kinetic constants k₁ and k₂ and the cure activation energies E₁ and E₂ obtained by the Arrhenius temperature dependence equation of the epoxy/phenol‐novolac/BPH blend system were mainly discussed as increasing the content of the phenol‐novolac resin to the epoxy neat resin. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 2945–2956, 2000     

Structure and properties of partially epoxidized soybean oil

In the present study, the characteric-structure relationship of epoxidized soybean oils (ESO) with various degrees of epoxidation has been investigated. FTIR analysis was used to identify the relative extent of epoxidation of the samples during the epoxidation reaction. The viscosities of ESO were much higher than that of the raw oil, viscosity increased with degree of epoxidation. The viscous-flow activation energy of ESO was determined to be higher than that of the raw oil (20.72 to 77.93% higher). Thermogravimetry analysis (TG) of ESO was used to investigate the thermodynamic behavior of the samples. With increasing degree of epoxidation, the thermal stability of the samples initially decreased, then increased at the final reacting stage. Differential scanning calorimeter (DSC) indicated that the melting point of ESO was higher than that of soybean oil. Gel permeation chromatography (GPC) indicated the molecular mass of the samples increased initially, then decreased, with an increase in the extent of epoxidation.     

Plasticizing and thermal stabilizing effect of bio-based epoxidized cardanol esters on PVC

Poly(vinyl chloride) (PVC) is a widely used plastics in different industries. It is an intrinsically hard and brittle polymer and requires the use of plasticizers to improve the processability. Commonly used phthalate-based plasticizers have serious toxicity issues and we present alternatives based on epoxidized soybean oil (ESO) and epoxidized cardanol esters (ECEs). ECEs are synthesized from cardanol and three fatty acids (oleic, ricinoleic, and myristic) using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) as a coupling agent. Their structure and purity are confirmed by Fourier transform infrared spectroscopy (FTIR) and Nuclear magnetic resonance. Moreover, plasticized PVC films are prepared using a solvent-free method. The replacement of 10 phr of ESO with 5 phr of ECE improves the plasticizing power due to the co-solvency effect. Mechanical properties and thermal stability of plasticized PVC films are correlated with the chain length and the number of epoxy groups in ECE. The best plasticizing effect is observed for epoxidized cardanol-myristate (ECD-MA). ECD-MA as a shorter-chain secondary plasticizer is more compatible with ESO and allows higher conformational mobility of PVC chains. PVC/30ESO/5ECD-MA polymer exhibits an exceptionally high initial thermal decomposition temperature (314.4°C) while preserving moderate ductility and tensile strength (263.4% and 23.3 MPa). Overall, this study highlights the potential applicability of ECD-MA in combination with ESO as a sustainable, bio-based plasticizer and heat stabilizer for flexible PVC products.     

Morphology and photoelectrochemical properties of TiO2 electrodes prepared using functionalized plant oil binders

Chemically functionalized plant oils, viz. acrylated epoxidized soybean oil (AESO) and maleinized acrylated epoxidized soybean oil (MAESO), were used as bio-based binders for the TiO₂ electrodes of dye-sensitized solar cells (DSSC). The surface roughness and number of appropriate pores were increased in the TiO₂ films prepared using the plant oil binders in comparison with the film prepared using polyethylene glycol (PEG), due to the larger number of functionalities. The short circuit photocurrent (I_SC) and open circuit photovoltage (V_OC) were increased, and the conversion efficiency was significantly improved, in the cell using the plant oil binders.     

Mechanical and thermal properties of epoxidized soybean oil plasticized polybutylene succinate blends

Epoxidized soybean oil (ESO) was blended as a novel plasticizer with polybutylene succinate (PBS) in a twin‐screw extruder. The effects of ESO on the mechanical and thermal properties of the PBS/ESO blends were investigated by means of tensile test, differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and scanning electronic microscope. ESO improved elongation at break for PBS, which increased and then decreased with the increase in ESO. Elongation at break reached a maximum of 15 times than that for pure PBS when the ESO loading was 5 wt%. The tensile strength and modulus for the blends were lower than those for pure PBS. Compared with pure PBS, the blends exhibited lower glass transition temperature, crystallization temperature, and melting temperature. The storage modulus and tan δ peaks for the blends were lower compared with that for pure PBS. ESO had very limited compatibility with PBS, and phase separation was observed when more ESO was added. Copyright © 2011 John Wiley & Sons, Ltd.