The Effects of DOPO-g-ITA Modified Microcrystalline Cellulose on the Properites of Composite Phenolic Foams

In order to improve the comprehensive performance of phenolic foam,9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide(DOPO)was grafted with itaconic acid(ITA)(DOPO-g-ITA)to modify microcrystalline cellulose(MCC).DOPO-g-ITA modified MCC(DIMMCC)was used to prepare composite phenolic foam(DCPF).The structures of DIMMCC were verified by Fourier transform infrared spectroscopy(FT-IR).The microstructure and crystalline property were characterized by scanning electron microscope(SEM)and X-ray diffraction(XRD)respectively.Compared with MCC,the crystallinity of DIMMCC was dramatically decreased,but the diffraction peak positions were unchanged.Thermal stability was decreased,and T_(i)decreased by 45.0°C.The residual carbon(600°C)was increased by 22.34%.With the dosage of DIMMCC/PR increased,compared with PF,the mechanical properties and flame retardancy of DCPF were increased.Especially,the dosage of DIMMCC/PR was 10%,the comprehensive properties of DCPF was better than others.

Synthesis and Characterization of DOPO-g-CNSL and Its Effect on the Properties of Phenolic Foams

In order to improve the mechanical properties without reducing its flame retardancy of phenolic foams(PFs),9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide(DOPO)was introduced in the structure of cashew nut shell liquid(CNSL)to improve its flame retardant,and the product of DOPO grafting CNSL(DOPO-g-CNSL)was obtained to modify phenolic resin,and to prepare DOPO-g-CNSL modified PFs(DCMPFs).The structures of DOPO-g-CNSL were verified by Fourier transform infrared spectroscopy(FT-IR)and nuclear magnetic resonance(1H-NMR).Compared with CNSL,thermal stability of DOPO-g-CNSL was decreased and Ti decreased by 3.53%,but the residual carbon(800°C)was increased by 35.05%.Compared with pure PF,the mechanical properties,toughness and flame retardancy of DCMPFs were increased when the ratio of DOPO-g-CNSL to phenol(DOPO-g-CNSL/P)was no more than 10%.With the dosage of DOPO-g-CNSL/P increased,Ti of DCMPFs was slightly increased,but the carbon residues(800°C)were almost unchanged.And the cell sizes of DCMPFs were basically the same as the pure PF.By comprehensive analysis,the suitable dosage of DOPO-g-CNSL/P was no more than 10%.

Preparation and Characterization of Tung Oil Toughened Modified Phenolic Foams with Enhanced Mechanical Properties and Smoke Suppression

In this study,we prepared a series of tung oil phenolic foams(TPF)by a one-pot method.The FT-IR and 1H NMR spectra confirm the successful Friedel-Crafts grafting of phenol to the long-chain alkyl group in tung oil.Modified TPFs exhibit enhanced mechanical properties,including compressive and flexural strengths of up to 0.278±0.036 MPa and 0.450±0.017 MPa,respectively,which represent increases of 68.75%and 86.72%over those of pure phenolic foam(PF).SEM spectra reveal the TPF microstructure to have uniform hexagonal cell morphology,narrower cell size distribution,and smaller mean cell size,suggesting enhanced mechanical properties.The TPF total smoke release decreased by 74.23%,indicating that the long alkyl chain significantly improves smoke suppression of the combusting foam.However,due to the flammability of the alkyl chains,the TPF limiting oxygen index decreases with increasing tung oil content.Moreover,TPF exhibits reduced thermal stability and high-temperature charring rate,elevated peak and mean heat release rates,and higher total heat release compared with pure PF.Therefore,future research will focus on the use of tung oil modified flame retardant to provide more robust phenolic foams.

Study on Toughening Phenolic Foams in Phosphorus-Containing Tung Oil-Based Derivatives

Phenolic foams(PFs)as thermal insulation material with outstanding flame retardancy are required to match society’s ever-expanding safety expectations;however,a trade-off exists between flame retardancy and toughness.Here,for the first time,we synthesized a novel reactive phosphorus-containing tung-oil-based derivative and used it to toughen PF,resulting in PFs with a combination of excellent mechanical properties and flame retardancy.Compared with pure PF,the modified PFs exhibit enhanced mechanical properties,with specific compressive and flexural strengths as high as 5.67 MPa and 12.46 MPa,which represent increases of 90.67%and 178.7%over those of pure PF,respectively.Meanwhile,the limiting oxygen index(LOI)values of the modified PFs are improved as much as 40.83%.Scanning electron microscopy micrographs show that the microstructure of the modified PFs is better than that of pure PF,with a more uniform cell morphology,a narrower pore size distribution range,and a smaller average pore size,all of which are beneficial to the foam’s mechanical properties.This study provides a scientific paradigm for the development of advanced PFs based on renewable biological resources.

Effects of Bamboo Fiber Length and Loading on Mechanical,Thermal and Pulverization Properties of Phenolic Foam Composites

In order to improve the mechanical properties and toughness of phenolic foams,a reinforcement method using two kinds of bamboo fibers was optimized with respect to the fiber contents.The compressive and flexural properties,thermal stability,friability and morphology of the phenolic foam composites were studied.The mechanical properties of the pristine foam and composites were evaluated by measuring the compressive strength.The results showed that the greatest mechanical properties were achieved by incorporating 2.5wt%of the reinforcement,and the compressive and flexural strengths of the two composites increased by 26.21%and 24.35%,respectively,compared with that of the pristine foam.The results of thermogravimetric testing demonstrated that the addition of bamboo fiber imparted better thermal stability to the phenolic foam,which was mainly attributed to the higher initial thermal decomposition temperature of the bamboo fiber.However,the influences of both reinforcements on the thermal stability of the material were negligible.The incorporation of bamboo fiber decreased the friability of the phenolic foam.Furthermore,the reduction in friability of the foam composites with longer lengths were higher than that in foams with shorter bamboo fibers.Moreover,the morphology and cell sizes of the fiber-reinforced phenolic foams were analyzed by scanning electron microscopy,the results indicated strong bonding between the fibers and phenolic matrix,and the incorporation of the bamboo fibers into the foam resulted in increased cell size of the material.Finally,the thermal conductivity and flame resistance of the phenolic foams reinforced by the bamboo fibers were also measured.

Heating Process of Thermosetting Insulation Materials for Buildings

Polyurethane （PU） and phenolic （PF） foams used for building isolation were analyzed by thermal gravity/differential thermal analysis to determine their pyrolysis behavior, including the decomposition point and the maximum reaction rate point. Besides, the shape deformations of PU and PF foams were observed, and their oxygen index and the calorific value in combustion were also studied. The results showed that the pyrolysis of both PU and PF can be divided into three stages from room temperature to 1 000 ℃ in the atmospheric air, with total mass loss of 94.345% for PF and 88.191% for PU, respectively. The oxygen index of PU and PF decreased with increasing the temperature and the duration of the heat treatment. With the temperature increasing, the calorific values of both materials were reduced remarkably. These results of the PU and PF could provide basic data of the thermal stability and fire safety design in the application of thermosetting insulation materials.

Lignin-based phenolic resin modified with whisker silicon and its application

In this study,lignin-based phenolic resin was modified with whisker silicon and preparation of the phenolic foam was carried out.The resin and foam materials were characterized by Fourier transform infrared spectroscopy(FT-IR),thermo gravimetric analyzer(TGA),thermal conductiv-ity test,limit oxygen index(LOI)analyzer and cone calorimeter.The results showed that when the content of lignin and whisker silicon increased,the oxygen index of the foam increases and the calorific value of combustion decreased.However,if the amount of lignin increased,the open porosity of the foam and the thermal conductivity increased.When the lignin substitution rate was 30%and the whisker silicon addition amount was 1%,the phenolic foam(PF4)had the best performance:the 57.1%mass lost at 600℃ and the thermal stability was 16.8%higher than that of ordinary resin.The LOI was 49.6%,and 39.3%higher than that of ordinary phenolic foam.