乙酸乙烯酯半連續法乳化聚合反應之研究

Studies on Semicontinuous Emulsion Polymerization of Vinyl Acetate

呂銘坤(Meng-Kun Lu) ； 游清文(Chin-Wen Yu)

《化學》 68年1期 (1979/03) Pp. 10-21

https://doi.org/10.6623/chem.1979003

摘要

乙酸乙烯酯(VAc)單體在一個充分攪拌且充滿純氮氣的反應器內使用硫酸十二基鈉為乳化劑，過硫酸鉀為起始劑，在50°C及攪拌速率的400 rpm條件下進行半連續法乳化聚合反應，以研討改變單體進料速率、乳化劑及起始劑濃度對聚合速率、本質黏度([ŋ])及分子量分佈的影響。由實驗結果顯示：(1)VAc的半連續法乳化聚合反應，其主要的反應場所仍在顆粒相內。(2)聚合速率在可控制區內略大於其進料速率；在泛濫區則與進料速率無關且保持定值。(3)在可控制區內的半連續法乳化聚合反應，其[ŋ]值在大部份反應過程的變化很小，且較囘分法所得為低。(4)平均分子量及本質黏度均隨進料速率之加快而增大，多分散性則遞減。(5)在低進料速率時，起始劑及乳化劑濃度對聚合速率幾乎沒有影響，但對[ŋ]值則略有影響，此現象有異於囘分法所得結果。

並列摘要

The semicontinuons emulsion polymerization of vinyl acetate (VAc) was carried out under nitroge atmosphere at 50°C with agitation rate of 400 r. p. m. in the presence of sodium lauryl sulfate as emulsifier and potassium persulfate as initiator. The effect of monomet addition rate, emulsifier concentration and initiator concentration on the polymerization rate, intrinsic viscosity and molecular weight distribution were studied. It was found that the main reaction locus of the semicontinous emulsion polymerization of vinyl acetate is still in the polymer particles. In controllable region, the polymerization rate is a little higher than the monomer addition rate; while in flooded region, it is independent of the monomer addition rate and keeps constant value. The intrinsic viscosity keeps constant value during most part of the reaction, but the value is smaller than which obtained from that of batch process. It suggests that different intrinsic viscosity depends mostly on the addition rate of vinyl acetate. Faster addition rate effects the increase of average molecular weight and the decrease of polydispersity. When the monomer is at a lower addition rate, the concentration of both initiator and emulsifier have some influence on the intrinsic viscosity, but there are almost no influence on the rate of polymerization.