Preparation And Properties Of Autocatalytic Cardanol Hydroxyl Derivatives And Their Polyurethane Foams

Polyurethane foams?PUFs?are widely used in various fields of national economy due to their excellent performance,and the application fields are still expanding until now.However,traditional petroleum based polyurethane foams are difficult to recycle and non-biodegradable,causing serious pollution to the environment.With the increasing emphasis on resource and environmental issues,the eco-friendly polyurethane foams become a research focus in various countries.Cardanol is a kind of natural phenolic compound with unique side-chain alkanes(C₁₅H_25³1),which is widely used and has outstanding environmental performance.The efficient development and utilization of cardanol are of great significance for promoting the healthy development of the forestry industry chain and relieving the pressure of resources and environment.In this thesis,a series of cardanol hydroxyl derivatives with autocatalytic properties were designed and synthesized.These compounds can not only spontaneously catalyze the foaming process of polyurethanes,but also control the reaction equilibrium between the foaming?water-isocyanate?and the gelling?polyol-isocyanate?reactions in the foaming process.Subsequently,biomass-based PUFs with excellent properties were prepared from the obtained cardanol hydroxyl derivatives and polyaryl polymethylene isocyanate?PAPI?without catalyst.Main emphases of this work were the preparation methods of cardanol amino-polyols,cardanol-based benzoxazine with hydroxyl groups and their PUFs,the property and mechanism of autocatalytic reaction and the relationship between the molecular structure and their properties.?1?Synthesis and reaction characteristics of cardanol amino-based polyolsFour types of cardanol-based polyols?CAP-1,CAP-2,SCAP-1 and SCAP-2?with different viscosities,molecular structures and autocatalytic activities were synthesized by series epoxidation,ring-opening and hydrosilylation reactions.The obtained autocatalytic polyols with high reactivity satisfied the requirements of industrial polyether polyols and could be used for the manufacture of PUFs.The reactivity and cross-linking kinetics between these four autocatalytic polyols with PAPI were studied with non-isothermal dynamic scanning calorimetry?DSC?.The apparent activation energies,kinetic parameters and kinetic equations of cross-linking reaction were analyzed and calculated using Málek method.The results showed the cross-linking reactions of these four autocatalytic polyols with PAPI fit the Seatak-Berggren two-parameter autocatalytic model?SB model?.?2?Preparation and properties of autocatalytic cardanol-based polyurethane foamsFour types of cardanol-based autocatalytic polyurethane foams?CAP-1/PUF,CAP-2/PUF,SCAP-1/PUF and SCAP-2/PUF?were prepared by the reactions between four types of cardanol autocatalytic polyols?CAP-1,CAP-2,SCAP-1 and SCAP-2?and PAPI without catalysts,using one-step foaming process and water as foaming agent.The compressive strengths of the obtained PUFs were ranked as follows:CAP-1/PUF>CAP-2/PUF>SCAP-1/PUF>SCAP-2/PUF,and the glass transition temperatures?T_g?of them were 160.30°C,110.13°C,145.77°C,and 110.03°C,respectively.The cells of these PUFs were uniform and polygonal in regular compact arrangement.TGA-FTIR and TGA-MS were used to analyze the thermal decomposition products of the foams.The results showed the thermal mechanism of these PUFs was a complicated process,including the initial degradation of urethane to polyol and isocyanate components,and their further decomposition to amines,aromatic hydrocarbons,small molecule hydrocarbons and carbon dioxide.?3?Synthesis of cardanol-based benzoximes with hydroxyl groups and their reaction propertiesThree types of cardanol-based benzoximes with hydroxyl groups?CBozH-1,CBozH-2and CBozH-3?were synthesized by the reaction of cardanol,formaldehyde and amino alcohol,and characterized by FTIR and NMR.The polymerization process of the three benzoxazines were studied by DSC.The result showed the thermal polymerization of CBozH-1,CBozH-2and CBozH-3 all followed the first-order reaction kinetics,their reaction orders were 0.9072,0.9094 and 0.9093,respectively.The apparent activation energies of these reactions were 81.75k J/mol,85.47 k J/mol and 87.42 k J/mol,respectively.These three CBozHs were heated and formed polybenzoxazines by self-polymerization?PCBozH-1,PCBozH-2 and PCBozH-3?.The abtained polybenzoxazines all had two glass transition temperatures and high thermal-stability.The thermal degradation mechanism of these polybenzoxazines was investigated by TG-FTIR-MS.The result showed the C-N and C-C bonds on the Mannich bridge were broken first at high temperature to form benzoxazine oligomers,benzoxazine monomers,cardanol formaldehyde oligomers and cardanol derivatives.And these degradation substances were further decomposed to small molecular saturated hydrocarbons,olefinic compounds,CO,CO₂,H₂O,alcohols,nitriles,amines,and aromatic hydrocarbon compounds.?4?Preparation and properties of flame retardant cardanol-based benzoxazine/polyurethane foamsHalogen-free flame retardant cardanol-based benzoxazine/polyurethane foams?CBozH/PUFs?were prepared via one-step method using CBozHs as raw material,tris?hydroxymethyl?phosphine oxide?THPO?as flame retardant and chain extender,and water as foaming agent.The limiting oxygen index?LOI?of CBozH-1/PUF,CBozH-2/PUF and CBozH-3/PUF were 28.1%,29.0%and 27.5%,respectively,when the content of THPO was15%.Cone calorimetry analysis showed the heat release rate?HRR?,the total heat release?THR?,the smoke production rate?SPR?and the total smoke release?TSR?of CBozH/PUFs greatly decreased with the addition of THPO.Carbon residue analysis showed the flame retardancy of the obtained PUFs was improved by combinating gas phase and condensed phase flame retardant of THPO.With an increase of THPO,the thermal stability of the PUFs was enhances remarkably.Because non-combustible compounds such as phosphoric acid and metaphosphoric acid formed in the early decomposition of THPO at low temperature effectively promoted the carbon formation,which deferred the thermal degradation of PUFs,and thereby improved the thermal stability of PUFs.