|
本論文研究聚合反應動力學及其反應器設計；論文注重在質量平衡及動力學的探討，
作為聚合反應器設計的基礎，共分成兩大部份。
第一部份：乳化聚合反應
一般在工業上殳學術上的研究均著重於分批台連續操作，各有其優缺點。分批式乳化
聚合的優點為聚體顆料濃度及轉化率較高，分子量較高，其缺點為不利於連續大量的
生產。而連續乳化聚合卻正好相反，其優點為可連續生產，且產品性質均勻；但缺點
為聚體顆粒濃度降低，轉化率極小。1969年Om(55)等提出播種槽的構想，似可兼備分
批式連續式操作的優點。但此方面的實驗證實至今仍很缺乏，本文實驗方面，首次利
用管內混合器（Hi-mixer）當作播種槽，由實驗證實其效果，理論方面，綜合Omi 及
Imoto 的觀念（35，34），建立一動力學模式，並首次以串聯攪拌槽模擬播種槽，預
測其反應轉化率及分子量的問題。
聚合實驗是以苯乙烯為單體，十二烷基硫酸鈉為乳化劑，過硫酸鉀為起始劑。研究的
方法為①分別探討分批式及連續式的乳化聚合反應，得到一動力學模式，與實驗結果
比較。②設計播種槽，由實驗探討其效果，並與理論作一比較。③對分批式，連續式
及播種連續式操作所得到的聚體顆粒，轉化率及聚體分子量作一比較和討論。
結果顯示，無論分批式、連續式或播種連續式操作，理論上對於轉化率、聚體顆粒濃
度及分子量的預期，均能與實驗結果相符合，最重要的是播種連續操作能提高連續乳
化反應的轉化率和分子量，其值介於分批和連續操作之間，而理論上以串聯攪拌槽模
擬管內混合器，亦能得到合理竹的說明。若能把播種槽規模放大，可得到最適的效果
，將可應用到工業上的生產。
第二部份：溶液共聚合反應
工業上以溶液共聚合方法生產的實例很多，生產技術已有相當的發展，但理論還很缺
乏，尤其是預測共聚物的分子量及其分佈，主要的是共聚合的反應機構非常複雜，若
用傳統的動力學作轉化率及分子量竹寺的預測太過於繁複。
本文首次提出“單位單體”的觀念將聚合反應的動力學簡化，其結果可合理的預測轉
化率及分子量，並由實驗證明其可行性。
共聚合實驗方面，以丙烯及苯乙烯為單體，過氧化二苯甲醯（Benzoyl peroxide）
為起始劑，甲苯為溶劑，在定溫下進行分批式聚合反應。研究的方法為①採用工業上
最重要的單體共沸組成，改變起始劑濃度或溶劑濃度，或溫度等條件，對轉化率、分
子量、分子量分佈及聚體組成等問題，作一探討。②利用“單位單體”的觀念演導動
力學模式，與實驗結果比較之。③將“單位單體”的觀念推廣到其他組成的共聚合反
應。
實驗結果證明，丙烯一苯乙烯的溶液共聚合，在溫度80 ∼100℃，起始劑濃度／單
體濃度比為3.0×10-4∼9.0×10-4，溶劑濃度／單體濃度比為0.6∼1.4，且轉化率在
50％以下的範圍，理論與實驗結果非常吻合。轉化率高於50％時，實驗顯示自加速作
用非常明顯，但其理論探討為本文範圍之外。
///////
THe topics on polymerization kinetics and reactor design are studied in
this thesis. Emphases are placed on the aspects of chemical kinetics and
material balance as they form the foundation for the proactice of reactor
design for all chemical works. The content of this paper is arranged in
two parts:
Part Ⅰ. Emulsion polymerization:
Industrial and theoretical researchers paid huge attention to the
comparison between batch and continuous operations of chemical reactors.
Among the advantages of batch operations of emulsion polymerizations are:
(1) high polymer particle concentration, (2) high conversion, and (3) high
molecular weight of product. One of the disadvantages of batch reactors is
the fact that they can not fulfill the requirement of mass production. On
the other hand, continuous operations usually reduce labour requirement
and produce products of uniform properties. However, disadvantages also
exist in continuous operations. Such as: (1) low polymer particle
concentration, (2) low conversion, and (3) low molecular weight of
product. Omi suggested in 1969 that a seeder reactor might retain all the
advantages of both batch and continuous reactors. However , few
experimental proofs have been presented in this respect. In this study, a
kinetic model based on Omi''s and Imoto''s concepts is formulated. An
internal mixer (Hi-mixer) has been used as the seeder reactor, and a
theoretical approach is adopted by assuming that a seeder reactor can be
simulated by a series of stirred tanks.
Styrene is used as monomer, sodium lauryl sulfate as emulsifier, and
potassium persulfate as initiator. First, a mew kinetic model of the
emulsion polymerization of styrene is established for both batch and
continuous reactors. Secondly, a seeder reactor is designed and used to
study the changes in conversion and molecular weight of polymer
experimentally. The results are then compared with theoretical
predictions. Overall performances of simulations among batch, continuous,
and seeder reactors are examined.
It is found that our kinetic model of emulsion polymerization of styrene
can give resonable predictions about monmer conversion, polymer particle
concentration, and molecular weight of the produced polymer in batch,
continuous, and seeder reactors. The experimental results show that the
seeder reactor can improve the conversion and the molecular weight of the
polymer which should be low in normal continuous operations. This fact can
be explained resonably by the theoretical treatment. It is concluded that
the use of seeder reactors provides a way for continuous emulsion
polymerization operations in the industrial production.
temperature between 80-100℃, mole ration of initiator to monomer between
3×10-4-9×10-4, and mole ratio of solvent to monomer between 0.6-1.4
untill 50% conversion is obtained. At higher conversions, the viscous
effect and diffusion should be considered. Within this 50% conversion
limit, no significant autoacceleration is observed. Results in this part
will serve as guide as to , in general terms, how the principle of "unit
monomer" is to be applied to the simulation models of solution
copolymerization for reactor design.
|