A renewable approach to thermosetting resins (original) (raw)
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Linseed oil‐based thermosets by Aza‐Michael polymerization
European Journal of Lipid Science and Technology
Aza-Michael addition on acrylated linseed oil (AELO) was performed to synthetize biobased bulk thermosets without any catalyst. First, acrylation of epoxidized linseed oil (ELO) allowed to obtain acrylate functions with vicinal hydroxyl groups which enhanced the reactivity of acrylates. The autocatalytic effect of hydroxyl groups on acrylate monomers was highlighted by kinetic studies monitored by NMR and FTIR analyses on model molecules. Then, Priamine 1071, amine terminated poly(propyleneoxide) (PPO) and metaxylylenediamine (MXDA) were used as cross-linkers with AELO. Curing kinetics were studied by DSC analyses to compare the reactivity of these structures. Priamine 1071 showed the highest reactivity; curing at room temperature was performed and high conversion was reached. Two enthalpies were observed with MXDA and only one at high temperature for PPO-based materials. Thermosets with a large range of mechanical properties were finally obtained from soft materials with PPO-diamine to hard materials with MXDA. Practical applications: Thermosets were obtained by curing AELO with various diamines via aza-Michael reaction. Model reaction allowed to demonstrate catalytic effect of hydroxyl groups on Aza-Michael reaction of acrylated oil with amines. Hence, linseed oil is a promising resource in terms of sustainable development in polymer science.
Plant oils as renewable precursors of thermosetting and flame retardant polymers
2009
Recent publications report the use of polyols derived from epoxidized plant oils for the preparation of polyurethanes, 19 polyurethane dispersions, polyurethane foams, 21 polyurethane IPNs 22 and hybrid latexes prepared from waterborne PU and acrylic MMA/BA copolymers. 23 Direct polymerization of epoxidized plant oils and fatty acids has also been reported with diamines, 24 anhydrides 25 or by cationic polymerization in the synthesis of linseed oil-POSS hybrid materials 26. As mentioned above, some plant oils present functional groups in their structure. Castor oil has lately found applications in the synthesis of hyperbranched polyurethanes 27 , in the synthesis of biodegradable plastic foams by curing with maleic anhydide 28 and in the preparation of UV-curable thiol-ene formulations. 29 An interesting castor oil derivative is 10-undecenoic acid, which is produced by cracking of castor oil under pressure. It is one of the oldest renewable building blocks, being used in the industry as a Nylon 11 precursor. It has been recently used for the synthesis of a variety of α,ω-dienes as interesting monomers for acyclic diene metathesis (ADMET) polymerization. 14 The dehydration of castor oil followed by crosslinking with bismaleimides via Diels-Alder reaction has been also recently reported 30. Another recent examples of fatty acid and plant oil-based polymers include the synthesis of polyols through Pd catalyzed cyclotrimerization of fatty acid derivatives for polyurethane synthesis, 31 the synthesis of isocyanate-containing triglycerides, 32 the preparation of thermosets from soybean oil and p-dinitrosobenzene via an ene reaction, 33 the development of a linseed oil-based thermoset via ROMP, 34 the cationic polymerization of soybean oil in supercritical CO 2 35 and the synthesis of soybean-based silicon-containing thermosets by cationic polymerization. 36 1 The Brundtland Commission, formally the World Commission on Environment and Development (WCED). Convened by the United Nations in 1983.
1992
2-(4-Carboxyphenyl)benzoxazole-5-carboxylic acid was prepared from silylated 3-amino-4-hydroxybenzoic acid and methyl 4-chloroformyl-1-benzoate in an "one-pot procedure". In addition to the free dicarboxylic acid the acid chloride was prepared and used as monomer. Polycondensations were conducted with the acetates or trimethylsilyl derivatives of phenylhydroquinone, phenylthiohydroquinone, 2,5-bis(phenylthio)hydroquinone and 4,4'-oxydiphenol. Furthermore, a copolyester containing 4-hydroxybenzoic acid was prepared. The resulting polyesters were characterized by elemental analyses, inherent viscosities, differential scanning calorimetry (DSC) and wide-angle X-ray scattering (WAXS) measurements and optical microscopy. The polyesters derived from monosubstituted hydroquinones and the copolyester were found to form nematic melts, whereas all other polyesters only form isotropic melts. The structure/property relationships are discussed by comparison with those of the corresponding poly(ester-imide)s.
Hybrid thermosets from vinyl ester resin and acrylated epoxidized soybean oil (AESO)
Express Polymer Letters, 2011
The synthesis of polymers from renewable resources is a preferred research topic nowadays. This is due to the eco-friendly classification of the related polymers which contribute to environment sustainability and to diminution of global warming by replacement of petroleum-based resins. Plant oils, being unsaturated triglycerides, are very promising raw materials for the 'greening' of thermosets. This note especially holds for soybean oil which may be 'genetically engineered' for such polymer-related application. However, the double bonds along the fatty acid chain in the triglycerides, even if the unsaturation level in the compounds is high enough, are less reactive towards free radicalinduced crosslinking than those in terminal positions. This is the reason why a large body of works addressed the 'functionalization' of plant (vegetable) oils to support the free radical-caused crosslinking and co-crosslinking (with other comonomers) reactions (e.g. [1, 2]). The related synthetic route starts usually with the epoxidation of the double bonds. Afterwards, these epoxy groups react with the carboxyl groups of selected acrylic acids. The resulting 2
Polymer, 2005
A range of thermoset plastics have been prepared by the cationic copolymerization of olive, peanut, sesame, canola, corn, soybean, grapeseed, sunflower, low saturation soy, safflower, walnut, and linseed oils with divinylbenzene or a combination of styrene and divinylbenzene comonomers catalyzed by boron trifluoride diethyl etherate. The chemical, physical, thermal, and mechanical properties of these new polymers have been investigated as a function of the vegetable oil composition. The vegetable oil reactivity has a direct effect on most of the polymers' properties, which can be reasonably predicted by careful choice of the vegetable oil. Coupled with variations in the comonomer and stoichiometry, the choice of vegetable oil allows one to tailor the polymer's properties for specific applications.
Journal of Polymer Science Part A: Polymer Chemistry, 2013
Phosphorus-containing thermosetting resins derived from high oleic sunflower oil were prepared through phospha-Michael addition of a difunctional secondary phosphine oxide, the 1,3-bis(phenylphosphino)propane dioxide on the a,b-unsaturated ketone derived from high oleic acid (ETR). The aim of this approach was to introduce phosphorus and to crosslink the material in one single step. Materials with increasing aromatic content were also prepared by addition 4,4 0-diaminodiphenylmethane and co-crosslinking through aza-Michael addition. The kinetics of the phospha and aza-Michael additions was investigated using the enone derivative of methyl oleate (EO) in presence of BF 3 ÁEt 2 O as catalyst and in absence of catalyst at different temperatures. Competitive experiments showed that phospha-Michael addition proceeds faster than the aza-Michael addition. The new triglyceride-based thermosets containing up to 4.2% of P, were characterized and their thermal and flame retardant properties evaluated. Limiting oxygen index values increase from 21.5 for the phosphorus free material up to 38.0 for the final material with 4.2% P content. These results demonstrate that the flame retardant properties of vegetable oil-based thermosets can be significantly improved by adding covalently bonded phosphorus to the polymer. V
Thermosetting polymers from renewable sources
Polymer International, 2020
Environmental concerns and the need for sustainable industrial practices have sparked the search for alternative materials that offered a lower impact on the environment. Over the course of the past few decades, numerous bio-based polymers have been developed from natural resources. Among the materials, bio-based thermosets are of particular interest due to their increased thermal stability in comparison to thermoplastics. This review covers recent advancements made on the field of bio-based thermosets, with a special focus devoted to resins prepared from vegetable oils, natural phenolic compounds, and a selection of other thermosetting systems developed recently based either on the polymerization of multifunctional monomers or the crosslinking of linear systems. This review article concludes with a critical perspective on the environmental implications of bio-based thermosets.
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
Biobased thermosets from the free-radical copolymerization of conjugated linseed oil
Journal of Applied Polymer Science, 2007
New polymeric thermosets were prepared through the bulk free-radical copolymerization of 100% conjugated linseed oil, acrylonitrile, and divinylbenzene. Under the appropriate reaction conditions and with the appropriate curing sequence, 61-96 wt % of the oil was incorporated into the crosslinked thermosets. The resulting yellow, transparent thermosets varied from being soft and flexible to being hard and brittle. Dynamic mechanical analysis and thermogravimetric analysis showed that these thermosets had good mechanical properties and thermal stability.
Journal of Applied Polymer Science, 2004
Simultaneous addition of bromine and acrylate to the double bonds of fatty acids in triglycerides was achieved. In the first part of the study, methyl oleate was bromoacrylated in the presence of acrylic acid and N-bromosuccinimide as a model compound for the application of the reaction to the triglycerides. Next, soybean oil and high oleic sunflower oil were bromoacrylated by using the same procedure. The products were characterized by GC, IR, 1 H-NMR, 13 C-NMR, and mass spectrometry. The bromoacrylation yields for soybean oil and sunflower oil were 75 and 55%, respectively. A rigid thermoset polymer was prepared from the radical copolymerization of bromoacrylated soybean oil with styrene. The bromoacrylated sunflower oilstyrene copolymer showed semirigid properties. The crosslinked network structure of the copolymers was examined by their swelling behavior in different solvents. Glass-transition temperatures were also determined and soybean oil-based polymer and sunflower oil-based polymer showed a glass transition at 55-65 and 20 -30°C, respectively. The storage moduli of the soybean-based and sunflower-based polymers at room temperature were approximately 1.0 ϫ 10 10 and 1.1 ϫ 10 8 Pa, respectively. Photopolymerization was also carried out by using 2,2-dimethoxy-2-phenyl-acetophenone as initiator. The response of the cured polymers to the thermal energy produced by a small flame was also tested by the ignition respond index method according to ASTM D 3713-78 and was found to be 5 B at 2.00 mm.