Synthesis Formulation And Characterization Of Phenol Formaldehydechitosan Composites

The methodology of the experiment involves three main stages. The first part describes thesynthesis of the PF (novolac) resins. Novolac (resins) were prepared with an excess of phenol overformaldehyde under acidic conditions. PF molar ratio were varied from 1P:2F to 1P:8F. Thestructure of the PF was determined using FT-IR techniques. The preparation and characterizationwas reported. The physicochemical properties tests carried out on the (novolac) resins include pH,viscosity, water-tolerance, density, resin solid content, gel time, cure time and yield%. Emissiontests such as free formaldehyde content and free phenol content were determined . The second partinvolves synthesis of chitosan from commercial chitin with different degree of substitutionsdetermined by potentiometric titration. Characterization using FT-IR of the fresh chitin and thedeacetylated chitosan was carried out and functional groups were observed and compared with thestandard values. The following analysis were carried out on the chitin: loss on drying, moisturecontent, % solubility, solubility in chemicals, density, pH value, and ash content. The solubility ofthe chitosan were tested in various solutions like distilled water, acetone, ethanol, acetic acid andlactic acid. The third part was the production of the composites with different P: F molar ratio 1P:2Fto 1P:8F and filler loading were varied 10% to 50%. A total of thirty five composites were produced,fabricated and subjected to mechanical properties.from the physiochemical properties of density,water absorption and tensile strength/modulus of composites at different filler loading of 10% to50% using 5%w/v Heaxemethylenetetramine (HMTA) as the hardener, loading of 40% with 1P:4Fand 1P:2F gave excellent results in terms of mechanical properties. The results of the mechanical properties revealed that the tensile strength and the tensile modulus increases with the increase ofthe filler loading. Further analysis was carried out to determine the optimum from the compositesat different filler loading. To prove the results, optimization of 1P:2F to 1P:4F were carried out withthe filler at different degree of deacetylation (DD) % values. In this case, the DD% values wereincreased by increasing the concentration of the alkali (NaOH) at 30%, 40% and 50%w/v at atemperature of 120oC. The approximate calculated values of 70%, 81.47% and 90.92% DD of thechitosan were obtained and composites using P: F molar ratio of 1P:2F and 1P:4F were prepared.The composites were then subjected to various analysis to obtain the optimization of thecomposites. In order to characterize the chitosan phenol formaldehyde composites, several analysiswere carried out on the following sample, neat polymer (100%), untreated, 70%, 81.47% and90.92% DD were carried out. Swelling behaviors tested using the following solvents water, carbon tetrachloride, ethanol and acetone, and the results obtained were reasonable. Chemical resistanceon the 40% of 1P:4F and 1P:2F were carried out in 1N HCl and 1N NaOH at 72 hours. A verygood results were obtained for samples 70%, 81.47% and 90.92% with an average result of around7%. But the basicity behaviors was poor in 1N NaOH solution with the highest value in theuntreated 12.5% were observed. Other tests carried out were density and water absorption, thedensities were in the range of 1.8g/cm3for 60% to 0.82g/cm3for untreated.The water absorptionmeasurement was found to be excellent in all the samples, lowest value was observed in 91% andhighest for 70% DD. Neat matrix showed complete resistance to water absorption. Mechanicalproperties tests of: tensile strength/modulus (38% improvement), flexural strength/modulus (27%improvement), impact (65% improvement) and hardness (25% improvement) of filler loading of40% at DD of 70% gave an excellent results. Formaldehyde emission test using flask method werecarried out on the composites. The effect of DD on emission was found to be highest in 70% DDand lowest in 91% DD. The effect of chitosan in reduction of formaldehyde release in theproduction of chitosan/P:F composite mechanism of reaction between chitosan and novolac resinwere drawn. The use of chitosan in the production of composite have significantly reduced theemission. The SEM studies of the samples were investigated and. morphological results clearlyshowed that when the polymer resin matrix was reinforced with the different loadings of chitosan70% to 90.92% DD surface modification took place. Wide angle x-ray analysis (XRD) was carriedout to investigate the effectiveness of the resin interaction Thermal analysis of the reinforcedchitosan phenol formaldehyde composites as compared to the virgin polymer had improved from330oC to 615oC. Improved stability was manifested throughout the whole range of temperaturestudied. The overall results of the research show that composites which were deacetylated,reinforced and cured with hardner (HMTA) gave excellent results than those without deacetylation and curing

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