Entry in Emulsion Polymerization-the molecular weight of surfactant NaPSS

• Main Authors: Han- Chou Chen, 陳漢洲
• Other Authors: Hou-Hsein Chu
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/40201226331355215497

碩士 === 逢甲大學 === 化學工程學所 === 96 === Using completely sulfonated polystyrene sodium sulfonate (NaPSS) with weight-average molecular (Mw) of 25000 and 70000, respectively , and sodium dodecyl sulfate (SDS), the emulsion polymerization of styrene was conducted to observe the entry of radicals. In each recipe, 1g of NaPSS and varied amount ( 0.3, 0.5 and 0.7g，respectively) of SDS were used. The NaPSS of 25000 was synthesized by the stable free radical polymerization procedure, while the one of 70000 was commercial products. Although two NaPSSs of different Mw have the equivalent functional number per unit weight, and the same critical micelle concentration (0.42g/100mL water), the two kinds of latexs particles have considerably different size. Recipes containing NaPSS (70000) have larger particle size and faster polymerization rate (Rp), and the same results were found for seeded emulsion polymerization. The long chain NaPSS was prone to limited aggregation to form larger particles, less particles number, and to accommodate more radicals per particle. The shorter chain NaPSS can produce tremendous particles, and the chain number per particle is extremely low. Comparing to results of using a mixture of partly sulfonated NaPSS (degree of sulfonation = 0.65) and SDS, we found the partly sulfonated system even has the larger particle size and the faster polymerization rate. Using different amount of initiator (potassium persulfate) but fixed amount of surfactant 1g of NaPSS and 0.5g of SDS in emulsion polymerization , both the latex particle number and Rp increase with increasing the initiator concentration. However, the Rp levels off and np decreases at higher initiator concentration.