甲醛高分子聚合物之研究

High Molecular Polymerization of Formaldehyde

任騰閣(Teng-Ke Jen)

《化學》 57年4期 (1968/12) Pp. 140-147

https://doi.org/10.6623/chem.1968023

摘要

本研究係用氰化鈉作觸媒（一種陰離子型觸媒），二甲甲醯胺（DMF）作介質，聚甲醛作原料，將熱解聚甲醛所生成之氣態單體甲醛，與氮氣流混合，隔絕氧氣，在-40～-70°C通入含氰化鈉之二甲甲醯胺內實行聚合。聚合時外加適量與適宜的「其他介質」（如三乙胺TEA），可改進聚合物之性質；如再加適量與適宜的「補正劑」（modifier）（如乙醇鈉），則更可提高聚合物之產率。本研究所得聚合物經化學分析，含甲醛99.5%，又經紅外線吸收光譜測定其爲多氧次甲基（polyoxymethylene）結構，故其分子式當為（CH_2O）_n，無疑。聚合物之物理性質：融點165~225°C；極限黏度0.51~2.3分升/公克；熱安定性，K222，12~25%/分鐘；強靱度15~20。聚合反應較好條件：（一）聚合反應溫度：-50～55°C，（二）氰化鈉用量：NaCN/DMF=1/4,000，（三）「其他介質」TEA/DMF=1/10，（四）「補正劑」乙醇鈉：TEA：DMF=1：100：20,000，聚合物產率33.3%，（五）甲醛氣流速度：75毫升/分鐘，聚合一次反應時間2.5小時。

並列摘要

Polymerizations of formaldehyde were studied in the presence of sodium cyanide as catalyst (one of the anionic chain transfer catalysts), dimethyl formamide (DMF) as reaction medium, and paraformaldehyde as raw material. Paraformaldehyde was pyrolyzed at about 160°C to gaseous monomeric formaldehyde which, after purified from moisture and precooled to -10～-15°C, was carried into the reaction medium solution (DMF and NaCN) by nitrogen and polymerized at -40～-70°C, therein. The physical properties of the polymer may be improved by adding a proper amount of another suitable medium (namely triethylamine, TEA) into the reaction medium solution. If an additional proper modifier (namely sodium ethoxide, NaOC_2H_5) in proper amount was added, the yield can also be increased. It had been demonstrated by chemical analysis that the polymer was composed of 99.5% formaldehyde. The infrared absorption spectra measurements indicated that it had a polyoxymethylene structure; It's chemical composition was therefore identified as (CH_2O)_n. The physical properties of the polymer obtained were: m.p. 165～225°C, intrinsic viscosity 0.51～2.3 dl/g. Thermal stability K222%/min 12～25; toughness 15～20. The preferable conditions of polymerization had been found to be: ( 1) Polymerization temperature: -50～-55°C. (2) Amount of catalyst NaCN: NaCN/DMF=1/4,000. (3)Additional medium TEA: TEA/DMF=1/10. (4)Modifier NaOC_2H_5:TEA:DMF=1:100:20,00 This was the most effective combination in this study, from which a 33.3% yield of polymer was obtained. (5)Flow rate of gaseous monomeric formaldehyde: 75ml/min, the polymerization time of a batch was 2.5 hours correspondingly.