A simulation model dealing with the kinetic behavior of the hydrolytic polymerization of c-caprolactam with bifunctional regulators has been proposed to analyse such characteristic data of the polymerization as the concentrations of caprolactam, endgroups, E-aminocaproic acid, cyclic dimer, and as well as conversion, numherand weight-average molecular weights, and polydispersity index. The calculated values based upon the model were found to be quite compatible with the observed values. It is found that the presence of more bifunctional acid leads to a lower equilibrium value of polydispersity index, unlike the case of monofunctional acid where the polydispersity index asymptotically reaches a value of 2, regardless of the amount of monofunctional acid initially added. ZUSAMMENFASSUNG:Ein Model1 zur Simulierung der Kinetik der hydrolytischen Polymerisation von E-Caprolactam mit bifunktionellen Molekulargewichtsreglem wird vorgeschlagen, um charakteristische Daten wie die Konzentrationen von Caprolactam, Endgruppen, E-Aminocapronsaure und cyclischem Dimeren sowie Umsatz, zahlen-und gewichtsmittlere Molekulargewichte und die Uneinheitlichkeit zu analysieren. Die anhand dieses Modells berechneten Werte stimmen gut mit den experimentellen Ergebnissen iiberein. Es wurde festgestellt, dal3 bei Venvendung bifunktioneller Saure als Regler mit zunehmender Reglerkonzentration die Uneinheitlichkeit abnimmt, wahrend sich mit monofunktioneller Saure als Regler die Uneinheitlichkeit mit steigender Reglerkonzentration asymptotisch einem Wert von 2 nahert.
Existem muitas substâncias que fizeram a história do século XX e contribuíram para os grandes desenvolvimentos queaconteceram durante esse longo período. Muitas destas substâncias foram descobertas por acidente ("serendipity") a caminho de pesquisa diferente e existem muitos casos de que nós poderíamos mencionar em especial na área de produtos químicos e polímeros. Mas não foi exatamente assim na história do nylon que estamos para contar, porque nesse caso foi o desejo de encontrar uma alternativa para a seda, o impulso para obter um substituto daquela fibra natural maravilhosa que só a natureza é capaz de sintetizar através de sínteses tanto difícil quanto precisas e rápidas e com métodos ainda a considerar se não inatingíveis certamente ainda não alcançados. O autor desse texto, deve ao polímero do qual vamos falar a história da própria vida científico-tecnológica e, por consequência, encontra-se em uma situação psicológica que o levará a empregar demasiada ênfase, mas pelo menos com conhecimento de causa. Podemos desculpar os excessos e a extensão do texto, incomum para esta revista. Muitas das informações históricas foram encontradas na internet; outra importante fonte informativa foi um livro intitulado "Os botões de Napoleão" que fala de 17 moléculas que mudaram o mundo e o nylon é uma dessas. Esperamos que os leitores sintam-se agradavelmente envolvidos por esta história
The use of Hindered Amine Light Stabilizers (HALS) directly in polyamide 6 polymerization can cause some problems. The following two problems were the focus of our project:1) We investigated, from a theoretical point of view, the results of introducing directly one of the precursors of HALS into polyamide 6 polymerization. For the investigation, 4 amino‐2,2,6,6‐tetramethylpiperidine (triaceton‐diamine or TAD) was chosen. We considered the TAD chain‐ending effects and their influence on the total amount of amino chain‐endings that can be titrated, a parameter of primary importance in the fibre field.2) We examined the amide interchange reaction in the case of an HALS containing two amide groups, using a product available on the market, N,N′‐bis(tetramethyl‐4‐piperidyl)isophtalamide. In this case we were able to generate a couple of equations that allows one to calculate the quantity of amide interchanged HALS. This was done by comparing the results (molecular weight and chain‐endings analysis) of polymerization with and without HALS.
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