Synthesis Of Degradable Formaldehyde Waterborne Acrylic Resin

Formaldehyde is a significant organic raw material for producing chemicals,such as urea-formaldehyde resins and pesticides,since it has strong reducibility.However,formaldehyde has a serious impact on people's health as one of the common pollutants in indoor air.Especially carcinogenicity has attracted people's attention.There are many methods for degrading formaldehyde,including plant adsorption,physical adsorption,photocatalytic degradation and chemical reactive degradation.Among them,plant adsorption and physical adsorption exists adsorption saturation,which will cause secondary pollution.Therefore,many studies are devoted to photocatalytic degradation and chemical reactive degradation.In this thesis,the acrylate?PMA?latex was modified by blending and chemical grafting,and the composite latexes which can degrade formaldehyde by chemical reaction were prepared.Additionally,we also synthesized the TiO₂ visible light photocatalysts modified by BP.The BP/TiO₂ composites were introduced to the polyacrylate latex which could catalytically degrade formaldehyde under ordinary visible light.The specific work includes the following aspects:?1?ADH/PMA composites were prepared by blending.The ADH aqueous solution was directly added to the PMA latex by physical blending.The UV characterization indicated that ADH could be uniformly dispersed in the PMA latex and maintained the stability of the latex.By SEM characterization,compared with pure PMA film,ADH/PMA film is slightly rough.The mapping mages showed that the N element was uniformly distributed in the ADH/PMA film.The AHMT method was used to verify the effect of formaldehyde degradation on composite films with 0%,2.5%,5%and 7.5%ADH.The results showed that the degradation of formaldehyde gradually increased with the increase of ADH.The degradation rate of formaldehyde was semi-quantitatively calculated to be 1.034*10² mol/?h·m³?by measuring the peak height of infrared amino absorption,when the polymer film was loaded by 5%ADH.TG results showed that the thermal stability of ADH/PMA film and ADH/PMA-HCHO film after formaldehyde absorption was improved compared with pure PMA film.The DSC results showed that the T_g of ADH/PMA film and ADH/PMA-HCHO film after formaldehyde absorption increased.?2?Chemical graft modification of PMA.Using OP-10 and SDS as complex emulsifiers,the latexes modified by MBA and DA with 1%,2%,3%,4%and 5%contents were prepared by semi continuous latex polymerization.Compared with the appearance of MBA/PMA latex and DA/PMA latex,MBA/PMA latex showed a slightly milky white,while the appearance of DA/PMA latex was slightly yellow white.The stability of latex was verified by UV spectrum.The results showed that the latexes were stable within 24h.SEM results showed that the compactness of MBA/PMA and DA/PMA films were almost the same as that of PMA films.Mapping results showed that the distribution of N elements in MBA/PMA composite films and DA/PMA composite films was uniform.The degradation of formaldehyde in MBA/PMA film and DA/PMA film was verified by AHMT method.The coloration results showed that the MBA chemical grafting modified PMA could not degrade formaldehyde.However,DA chemical grafting modified PMA could completely degrade formaldehyde with only 1%DA loading.Combining the reaction mechanism of MBA and DA with formaldehyde,the reason for the above phenomenon is that the amine group in MBA belongs to the amide,and the carbonyl group in the amide forms a conjugation with the lone pair electron of the amine group,which inhibits the reactionactivity of the amine group to some extent,so formaldehyde degradation is invalid.The amino group of DA is a methylene group,which belongs to the electron donating group and promotes the reactivity of the amine group with formaldehyde.Therefore,DA chemical grafting modified PMA could degrade formaldehyde.?3?Preparation of BP/TiO₂/PMA composite latex.TiO₂ was prepared by sol-gel method.The XRD result showed that the synthesized TiO₂ was anatase with high crystallinity.The TiO₂ particle size was about6 nm.A BP modified TiO₂ photocatalytic composite dispersion with a concentration of 0.49%was prepared by a simple ultrasonic method.The results of TEM and AFM showed that the prepared BP was 2-3 layers.The nano-TiO₂ was uniformly supported on the nano-BP sheet combining with the mapping results.The XRD test results showed that the particle size of TiO₂ modified by BP was slightly larger.The Raman and XPS test results revealed that the P element formed P-O-Ti in the form of a substituted Ti site.The prepared BP/TiO₂ nanocomposites were blended with latex,and the catalytic effect was verified by photocatalytic degradation of free formaldehyde.The AHMT results showed that the addition of 0.1125%BP/TiO₂ nanocomposite could completely degrade formaldehyde.The photocatalytic mechanism of BP/TiO₂ indicated that the formation of P-O-Ti bond lead to the imbalance of charge between atoms,which reduced the recombination rate of photogenerated holes and photogenerated electrons,thereby improving the catalytic ability of TiO₂in the visible wavelength range.