Linseed oil‐based reactive diluents preparation to improve tetra‐functional epoxy resin properties

Two kinds of bio‐resourced reactive diluents have been synthesized from linseed oil. The prepared epoxidized linseed oil (ELO) and the cyclocarbonated linseed oil (CLO) were separately blended with a petroleum‐based tetra‐functional epoxy resin (TGDDM) to improve its processability and to overcome the brittleness of the thermoset network therefrom. The linseed oil modifications were spectrally established, and processability improvement of the resin blends was rheologically confirmed. The curing of samples was studied by differential scanning calorimetry, and their mechanical properties (ie, tensile, flexural, fracture toughness, and adhesion) were investigated as well. Scanning electron microscopy images were obtained to reconfirm the toughness improvement of the modified thermosets. In contrast of the epoxidized soybean oil (ie, the most conventionally studied bio‐based reactive diluent), ELO and CLO had no negative effects on the thermoset material characteristics. They improved properties such as tensile strength (up to 43.2 MPa), fracture toughness (1.1 MPa m^1/2), and peel‐adhesion strength (4.5 N/25 mm). It was concluded that ELO and CLO were efficient reactive diluents to be used in formulations of polymer composites, surface coatings, and structural adhesives based on epoxy resins.     

Development of toughened bio‐based epoxy with epoxidized linseed oil as reactive diluent and cured with bio‐renewable crosslinker

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 ¹H 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.     

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.

     

环氧化蓖麻油的合成及表征

采用酸性氧化铝做催化剂对蓖麻油(CO)进行环氧化,探索环氧化反应时间、反应温度和催化剂等不同条件对蓖麻油环氧化的影响,从而优化出合适的反应条件,采用傅立叶变换红外光谱法(FTIR)、热重分析法(TG)对制备的环氧化蓖麻油(ECO)的结构和性质等进行了研究。利用盐酸-丙酮法对环氧化产物进行环氧值的测定,结果表明,在优化条件下,即采用酸性氧化铝做催化剂,H₂O₂的滴加温度保持在50～55 ℃,反应温度65 ℃,反应时间控制在11.5 h,同时同时加入尿素做稳定剂,可以提高H₂O₂的利用率,使环氧化蓖麻油的环氧值达到2.094×10_-3 mol/g。 对ECO的性能表征结果表明,ECO粘度随着环氧值的增大而增大,随着温度的升高而降低。 ECO在250 ℃前能够基本保持稳定,而后开始分解,有3个明显的热分解阶段：250~390 ℃、390~470 ℃、470~580 ℃,ECO的热稳定性较好。     

A fully biobased epoxy resin from vegetable oils: From the synthesis of the precursors by thiol‐ene reaction to the study of the final material

A novel vegetable oil‐based polyamine issued from grapeseed oil (GSO) was prepared using cysteamine chloride (CAHC) by thiol‐ene coupling (TEC). The structure of the polyamine oil (AGSO) was carefully examined using a large range of chemical analyses (FTIR, ¹H NMR and ¹³C NMR, LC‐MS…). The effects of the amination of GSO on the vegetable oil properties were also studied using viscosimetry. Then, AGSO was employed as a novel curing agent for bio‐based epoxy resin. The thermal crosslinking reaction between AGSO and epoxidized linseed oil (ELO) was studied by DSC and rheology. This study also dealt with the definition of the thermomechanical properties of the final material obtained by the mixing and curing of AGSO with ELO in stoichiometric proportions. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Synthesis and Thermal Properties of Epoxidized Vegetable Oil

Summary: The novel potential epoxy resins, epoxidized soybean oil (ESO) and epoxidized castor oil (ECO), were synthesized and characterized. The cationic polymerization of ESO and ECO with a latent thermal catalyst, N‐benzylpyrazinium hexafluoroantimonate (BPH), was initiated at 80 and 50 °C, respectively. The cured ECO samples showed a higher T_g and lower coefficient of thermal expansion than those of ESO, due to the higher intermolecular interaction in the ECO/BPH system.

Relationships between ESO or ECO conversion and temperature in the polymerization with 1 wt.‐% BPH for 2 h.     

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.     

Reduction of Epoxidized Vegetable Oils: A Novel Method to Prepare Bio‐Based Polyols for Polyurethanes

A novel method, epoxidation/reduction of vegetable oils, is developed to prepare bio‐based polyols for the manufacture of polyurethanes (PUs). These polyols are synthesized from castor oil (CO), epoxidized soybean oil, and epoxidized linseed oil and their molecular structures are characterized. They are used to prepare a variety of PUs, and their thermomechanical properties are compared to those of PU made with petroleum‐based polyol (P‐450). It is shown that PUs made with polyols from soybean and linseed oil exhibit higher glass transition temperatures, tensile strength, and Young's modulus and PU made with polyol from CO exhibits higher elongation at break and toughness than PU made with P‐450. However, PU made with P‐450 displays better thermal resistance because of tri‐ester structure and terminal functional groups. The method provides a versatile way to prepare bio‐polyols from vegetable oils, and it is expected to partially or completely replace petroleum‐based polyols in PUs manufacture.

     

Synthesis and Properties of Renewable Environment‐Friendly Epoxy Resins for Surface Coatings

Sunflower, soybean, and linseed oils are renewable resources that can be readily epoxidized. Epoxidation of these oils has the potential for use as an environmentally friendly, reactive material in pigmented formulation, designed for use as functional coatings. This study concern the synthesis of phthalimide modified epoxy compounds through reacting N‐(2‐hydroxyethyl) phthalimide (HEP) with epoxidized sunflower, soybean and linseed oils. The resulting compounds possessed both oxirane ring and phthalimide group. Incorporation of phthalimide group into epoxy resins provided cyclic imide structure and high cross‐linking density to the stoved resins, to achieve good mechanical characteristics and high chemical resistance to these resins. The films of phthalimide sunflower, soybean and linseed‐based epoxy resins were found to be similar with respect to resistance to water, alkali, acids, and solvents as well as gloss%, adhesion, impact, hardness, bending, and flexibility.     

New hybrid materials based on double‐functionalized linseed oil and halloysite

A series of hybrid systems which combine double‐functionalized linseed oil (methacrylated epoxidized linseed oil) and 2 types of functionalized halloysite (methacrylated halloysite and epoxidized halloysite) was designed in the current study. The curing of the new formulated oil‐clay mixtures was performed via 2 different mechanisms under the influence of the temperature: free‐radical and anionic polymerization. The effect of the functionalized clay tubes against the oil‐based macromonomer reactivity, representing the focus of this study, was monitored by differential scanning calorimetry and Fourier transform infrared spectrometry, concluding that both types of halloysite nanotubes (HNTs) exhibit significant influence on the building of methacrylate/epoxy networks. The effect of the HNTs on the methacrylated epoxidized linseed oil network properties was studied by dynamic mechanical analysis and thermogravimetric analysis, and the morphology of the synthesized hybrids was investigated by scanning electron microscopy. The results suggested that the designed oil‐based hybrid performance is determined by the presence of the both HNT molecules.     

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.     

Biobased epoxy/carbon fiber composites: Effect on mechanical,thermo-mechanical and morphological properties

Biobased epoxy was synthesized from diglycidyl ether of bisphenol A (DGEBA) and epoxidized castor oil (ECO) at a ratio of 80:20. Carbon fiber (CF) was used as a reinforcing agent to fabricate composites using biobased epoxy as matrix. Mechanical, Thermal and morphological properties of neat epoxy and biobased epoxy composites were investigated. Mechanical test results revealed that the composites prepared using five plies were higher than those with three plies and one ply respectively. This phenomenon revealed the effective reinforcing effect of carbon fiber due to its higher strength and higher crosslinking density. The composites also demonstrate high damping behavior as compared with neat epoxy and biobased epoxy blend. With increasing number of plies the composites thermal properties also shows an improvement. The SEM micrographs of the composites depicted that the biobased epoxy was fully adhered to the carbon fiber, thus representing a strong interface between CF/epoxy matrix.     

A Comparison of the Syntheses of High Molar Mass Epoxy Resins on the Basis of two Groups of Modified Vegetable Oils

Application of epoxidized and hydroxylated natural oils as a new group of environmentally friendly and renewable raw materials for the synthesis of high molar mass epoxy resins is described. Selected vegetable oils were first oxidized and next reacted with mono and diethylene glycols. Obtained epoxidized soybean, rapeseed, linseed and sunflower oils were used together with Bisphenol A in the fusion process. Analogously, hydroxylated soybean and rapeseed oils were reacted with commercial grade Bisphenol A-based low molar mass epoxy resin. The fusion process was carried out in the presence of selected catalysts (i.e., lithium chloride, 2-methylimidazole, triphenylphosphine and triethanolamine) giving high molar mass epoxies. The relationship between type of modified oil used in the synthesis and reaction conditions and properties of synthesized resins (e.g., value and distribution of average molar mass, contents of epoxy groups and colour) is discussed.     

Synthesis and Characterization of a Bio-Based Resin from Linseed Oil

Summary: The use of renewable raw materials in the polymer industries is becoming increasingly popular because of environmental concerns and the need to substitute fossil resources. Plant oils with triglyceride backbones can be chemically modified and used to synthesize polymers from renewable resources (biopolymers). In the present study, linseed oil was epoxidized using a chemo-enzymatic method based on Candida Antarctica lipase B (CALB) as a biocatalyst and the modified linseed oil was cured using maleinated linseed oil and a commercial polyamide resin. The amount of epoxidation achieved depended on the amount of lipase used and was determined by infrared (IR) and nuclear magnetic resonance (NMR) spectroscopies. With 20% (weight per weight) catalyst concentration based on the wt % of oil a degree of epoxidation of > 90% was achieved. The cross-linking reaction of epoxidized linseed oil with the maleinated linseed oil and the polyamide resin was studied using differential scanning calorimetry (DSC). DSC traces showed that an increase in epoxidation degree lead to larger values for the exothermic enthalpy integrals of the curing reactions and hence to a higher reactivity of the linseed oil towards the cross-linking agents.     

“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     

INTERPENETRATING POLYMER NETWORKS BASED ON OIL MODIFIED CASTOR OIL URETHANE AND POLY(METHYL METHACRYLATE)

Castor oil was initially subjected to an interesterification reaction with linseed and tung oils and the resulting intermediate was used for the preparation of polyurethanes and their IPNs with poly(methyl methacrylate). They were characterized for their physico-mechanical, swelling, and thermal properties. The morphologies of IPNs were studied with the aid of scanning electron microscopy and differential scanning calorimetry. On comparing the mechanical properties of castor oil polyurethane (CU) and their IPNs (C-IPNs) with those of the castor oil modified with linseed and tung oil (L-IPN and T-IPN, respectively) it was found that L-IPNs showed higher tensile strength, hardness, and better compatibility than C-IPNs. All IPNs showed synergistic effect in elongation and exhibited similar thermal behavior with no significant change with respect to their composition. However, the castor oil polyurethane and their IPNs showed relatively higher elongation and better resistance to solvents.     

Synthesis and Characterization of Acrylated Epoxidized Castor Oil Nanocomposites

Renewable resource-based epoxidized castor oil (ECO) was synthesized and used as a prime material to develop acrylated epoxidized castor oil (AECO) networks. AECO nanocomposites were prepared by the sol-gel method from organo-modified montmorillonite (OMMT) clay and silane. It was found that the AECO/1 wt.% OMMT system increased in tensile strength from 28 to 37 MPa and flexural strength from 54 to 63 MPa as compared with the AECO system. The non-isothermal cure kinetics of the bio-based systems was studied using differential scanning calorimetry. The activation energy of the AECO/OMMT system obtained from Kissinger and Flynn-Wall-Ozawa models is lower than that of AECO system.     

Synthesis and characterization of itaconic‐based epoxy resins

A trifunctional epoxy resin from itaconic acid (TEIA) was synthesized from a renewable resource‐based itaconic acid by allylation of itaconic acid to form diallyl itaconate by using m‐chloroperoxybenzoic acid as oxidizing agents followed by epoxidation of allylic C═C bond of diallyl itaconate methylhexahydropthalic anhydride as curing agent in the presence of 2‐methyl imidazole as a catalyst. The chemical structure of the synthesized resins was confirmed by Fourier transform infrared and nuclear magnetic resonance (¹H‐NMR and ¹³C‐NMR) spectroscopy analysis. The mechanical, thermal, and rheological performances of the TEIA were also investigated and compared with diglycidyl ether of bisphenol A and a plant‐based epoxidized soybean oil bioresin cured with the same curing agent. The higher epoxy value of 1.02, lower viscosity (0.96 Pa s at 25°C), higher mechanical, and higher curing reactivity toward methylhexahydropthalic anhydride of TEIA as compared with epoxidized soybean oil and comparable with diglycidyl ether of bisphenol A demonstrated significant evidence to design and develop a novel bio‐based epoxy resin with high performance to substitute the petroleum‐based epoxy resin.     

Effect of structure on properties of polyols and polyurethanes based on different vegetable oils

We synthesized six polyurethane networks from 4,4′‐diphenylmethane diisocyanate and polyols based on midoleic sunflower, canola, soybean, sunflower, corn, and linseed oils. The differences in network structures reflected differences in the composition of fatty acids and number of functional groups in vegetable oils and resulting polyols. The number average molecular weights of polyols were between 1120 and 1300 and the functionality varied from 3.0 for the midoleic sunflower polyol to 5.2 for the linseed polyol. The functionality of the other four polyols was around 3.5. Canola, corn, soybean, and sunflower oils gave polyurethane resins of similar crosslinking density and similar glass transitions and mechanical properties despite somewhat different distribution of fatty acids. Linseed oil–based polyurethane had higher crosslinking density and higher mechanical properties, whereas midoleic sunflower oil gave softer polyurethanes characterized by lower T_g and lower strength but higher elongation at break. It appears that the differences in properties of polyurethane networks resulted primarily from different crosslinking densities and less from the position of reactive sites in the fatty acids. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 809–819, 2004     

Synthesis,Characterization and Properties of Novel Amphiphilic Phosphated Ionomers by Ring‐Opening Reaction of Epoxidized Styrene‐Butadiene‐Styrene Triblock Polymer

A method for synthesis of novel phosphated ionomer of (styrene‐butadiene‐styrene) triblock polymer (SBS) from epoxidized SBS was developed. The optimum conditions for the ring‐opening reaction of the epoxidized SBS with aqueous solution of disodium hydrogen phosphate were studied. It was found that during the ring‐opening reaction phase transfer catalyst, ring‐opening catalyst and pH regulator were necessary to enhance the conversion of epoxy groups to ionic groups. The products were characterized with Fourier Transform Infrared Spectrophotometry (FTIR) and transmission electron microscopy (TEM). Some properties of the phosphated ionomer were studied. With increasing ionic groups or the ionic potential of the cation of the ionomer, the water absorbency emulsifying volume and the intrinsic viscosity of the ionomer increase, whereas the oil absorbency decreases. The ionomer possesses excellent emulsifying property, as compared with the sulfonated ionomer. The disodium phosphated ionomers in the presence of 10% zinc stearate showed better mechanical properties than the original epoxy SBS. Optimum mechanical properties occurred at the ionic group content of 0.95 mmol/g ionomer. When the ionomer was blended with crystalline polypropylene, a synergistic effect occurs with respect to the tensile strength. The ionomer behaves as a compatibilizer for blending equal amount of SBS and oil‐resistant chlorohydrin rubber (CHR) to form an oil resistant thermoplastic elastomer. SEM microphotographs indicated enhanced compatibility between the two components of the blend in the presence of the ionomer.