Synthesis And Sulfontion Of Naphthalene-Based Pitch Resin

Ion exchange resin has broad application in the field of water treatment, metallurgy, biology, medicine, catalysis, etc. As a new type of thermosetting polymer materials, the pitch resin possesses excellent performances, such as good chemical stability, high mechanical strength and extensive synthetic materials, etc. In the late 1980 s, the domestic and foreign scholars have carried out extensive research on it. In recent years, the research relating to the ion exchange resin prepared by sulfonated pitch resin ion attracted people’s attention.In this paper, the NP-BA pitch resin and NP-PXG pitch resin have been synthesized by using naphthalene(NP) as the monomer, benzaldehyde(BA) or 1,4-benzenedimethanol(PXG) as cross-linking agent, under the catalysis of concentrated sulfuric acid or p-toluenesulfonic acid(TSOH). Then, the two kinds of pitch resin were treated by using concentrated sulfuric acid as sulfonating reagent and the ion exchange capacity of the pitch resin was investigated. The pitch resin’s chemical structure was characterized by Fourier infrared spectrum(FT-IR), proton NMR spectra(1H-NMR) and VPO determinator. The thermal stability was analyzed by thermo gravimetric analyzer(TG/DTG) and differential scanning calorimeter(DSC). Then the effect of synthesis process on the bonding properties of the pitch resin was investigated and the relationship between the sulfonating conditions and the ion exchange properties of sulfonated pitch resin were discussed. The main research results were as follows:(1) FT-IR and 1H-NMR analysises showed that the synthesis mechanism of naphthalene-based pitch resin was cationic polycondensation initiated by carbocation. The average molecular of NP-BA pitch resin and NP-PXG pitch resin measured by VPO determinator was 794 and 1115 respectively.(2)Single factor investigation of synthsis conditions of pitch resin showed that the suitable synthesis conditions of NP-BA pitch resin were as follows: 1:1.0~1:1.5(the raw material ration), 150 oC, 180 min, 8~10%(mass fraction of the catalyst content), and the suitable synthesis conditions of NP-PXG pitch resin were as follows: 1:1~1:1.2(the raw material ration), 120 oC, 90 min, 5~7%( mass fraction of the catalyst content);(3) TG/DTG curve showed that the NP-BA pitch resin had three stages of weight loss, i.e. room temperature~200oC, 200~400oC and 400~630oC, and its percent of weight loss was 4.56%, 33.57%, 38.40% and the NP-PXG pitch resin had two stages of weight loss, i.e. room temperature~400oC and 400~620oC, and its percent of weight loss was 8.3% and 65.3%.(4) The apparent solubility of B-stage pitch resin was in sequence of chloroform > tetrahydrofuran > quinoline > toluene > heptane.(5) The sulfonation experimental results show that the ion exchange capacity of the sulfonated NP-PXG pitch resin was higher than the sulfonated NP-BA pitch resin. Under the conditions of 150 oC, the NP-PXG pitch resin(90 mesh) was sulfonated for 12 h and its ion exchange capacity was 3.798mmol/g. its its ion exchange capacity was slightly lower than 001×7 type strong acid styrene ion exchange resin(4.5mmol/g).