Molecular weight distribution in anionic polycaprolactam

✍ Scribed by G. Stea; G.B. Gechele

• Book ID: 103069196
• Publisher: Elsevier Science
• Year: 1965
• Tongue: English
• Weight: 526 KB
• Volume: 1
• Category: Article
• ISSN: 0014-3057
• DOI: 10.1016/0014-3057(65)90039-x

✦ Synopsis

We examined the molecular weight distribution in polycaprolactam obtained at 180: with sodium hydride and acetylcaprolactam. The polymer was fractionated in a continuous procedure with phenol/water system at 70:. Titration of acetyl end groups in the various polymer fractions led to values of Mn. At all stages of the polymerization, the molecular weight distribution seems very narrow in agreement with the step-addition process of the lactam molecules. Fractionations of samples, made with the same catalyst system but above the polymer melting point (220°), were also carried out. In this case, the method just mentioned could not be used to find Mn because of the presence of free amino end groups. According to recent theories, this could indicate the presence of branched products together with smaller linear molecules. Indirect measurements suggested a progressive broadening of the distribution. This effect suggests the occurrence of transamidation reactions in the molten state.