Preparation Of Vegetable Oil-Based Polyol By Epoxy-Ring Opening Method And Its Application

Polyols are not only a kind of important fine chemical but also the major raw material for the synthesis of polyurethane.However,most of the polyols currently used in the industry are non-renewable petroleum-based polyols.The exhaustion of global fossil fuel resources and consequent environmental problems have led to the exploration of renewable raw materials and sustainable development.Because it's renewable,biodegradable,non-toxic and inexpensive,vegetable oil has always attracted the academical and industrial researchers.In order to explore the better application of polyols in industry,vegetable oil was selected as the material and its functional groups were transformed through epoxidation and ring-opening reactions.Three kinds of polyols with different properties were obtained by different ring-opening agents and polyurethane films were prepared by the polyols.The main research contents of this paper were as follows:Epoxy soybean oil(ESO)was synthesized from soybean oil(SBO)through selective oxidation of double bond.And the magnetic solid acid catalyst(SO₄^2-/Zr O₂/Fe₃O₄)suitable for the ring-opening reaction of epoxy vegetable oil was prepared by using Zr OCl₂·8H₂O and nano-Fe₃O₄as raw materials.The vegetable oil-based polyols with high hydroxyl value were prepared by using ESO as the raw material,the magnetic solid acid as the catalyst and glycerinum as the ring-opening agent.The effect of the reaction temperature,the reaction time and the dosage of catatlyst on the ring-opening conversion and hydroxyl value of the product were investigated.The experimental results showed that the best reaction conditions were as follows,the reaction temperature was 80°C,the reaction time was 6 h and the catalyst dosage was 1.0%of the mass of ESO.The ring-opening conversion was more than 99%,and the hydroxyl value of the product was 365 mg KOH/g under the best reaction condition.Moreover,both the thermal property and the mechanical property of the polyurethane films prepared by the vegetable oil-based polyols with high hydroxyl value were excellent.To improve the poor hydrophobicity of polyurethane materials,fluorine was introduced into the structure of the polyols through ring-opening reaction by using the epoxy soybean oil(ESO)as the raw material,the magnetic solid acid prepared above as the catalyst and the trifluoroacetic acid as the ring-opening agent.The conditions of the ring opening reaction were optimized and the structure of the polyols was characterized.Then,polyurethane films were prepared by mixing the resultant polyols(SFP)and polytetrahydrofuran(PTMG)with isophorone diisocyanate(IPDI)in different proportions.The hydrophobic property of the PU films was studied by the water absorption test and the static contact angle measurement.The results showed that as the amount of SFP increased,the water absorption of the polyurethane films decreased from 4.2%to 0.5%,the static contact angle of polyurethane films improved from 69.8°to 93.8°without adding any other hydrophobic agent.Therefore,it was observed that the PU films prepared by SFP had superior hydrophobic property.The poor flame-retardant performance of traditional polyurethane was determined by its molecular structure.Therefore,vegetable oil polyols containing nitrogen and phosphorus(PNP)was synthesised by using methyl oleate as raw material through three steps:amidaion,epoxidation and ring-opening reaction with the magnetic solid acid as the catalyst and the dibutyl phosphate as the ring-opening agent.The structure of PNP was characterized.Then,polyurethane films were prepared by mixing the resultant polyols(PNP)and polytetrahydrofuran(PTMG)with isophorone diisocyanate(IPDI)in different proportions.After that,the thermal stability of polyurethane films was investigated by limiting oxygen index analysis,thermogravimetry test,cone calorimeter test and vertical combustion test.Similarly,mechanical property of polyurethane films was studied by tensile test.The results showed that as the amount of PNP increased,the initial decomposition temperature of polyurethane films improved from 176°C to 326°C,the LOI values of polyurethane films went up from 20.4%to25.5%,and the total heat release drooped from 32.2 k W/m² to 21.7 k W/m² without adding any other flame retardant.Moreover,the tensile strength of polyurethane films increased from 2.0MPa to 13.5 MPa.Therefore,it was observed that the PU films prepared by PNP had superior thermal stability and mechanical property.The results provided the original basic data for the pilot test and further industrialization and the polyols appeared suitable for a wide range of applications in the industry.