In the presence of water or catalysts giving off water, caprolactam is polymerized by several reaction mechanisms taking place simultaneously. It was investigated whether the formation of polyamide takes place according to a polycondensation or polyaddition mechanism in the presence of phosphoric acid. In order to prove the polycondensation mechanism, the formation at 250°C. of a mixed anhydride from the carboxylic acids and the orthophosphoric acid was studied. N‐phosphoryl aminocaproic acid has also been synthesized. No catalytic effect was exerted by this compound; on the basis of this fact it can be stated that in the case catalysis by orthophosphoric acid, the increase of the polyamide chain does not take place according to a polycondensation mechanism. The adduct of caprolactam and orthophosphoric acid is able to catalyze the polymerization of caprolactam. Polymerizations carried out at temperatures ranging from 170 to 200°C. proved that the acid—amide bond of the caprolactam ring is weakened by the phosphoric acid, thereby rendering possible the polymerization to take place at a lower temperature. At elevated temperatures (exceeding 160°C.), the ammonium salts of phosphoric acid undergo dissociation; thus, free orthophosphoric acid is always present in the mixture undergoing polymerization. Due to the dissociation at higher temperatures, the phosphoric acid yields a product having higher molecular weight than at lower temperatures. It has been established that the rate of polymerization is directly proportional to the square root of the molar concentration of the free orthophosphoric acid. The activation energy of the polymerization catalyzed by phosphoric acid was 46 kcal./mole.

The polymerization of caprolactam taking place in the presence of water has been investigated by a number of authors. On the basis of 11-ork by Wiloth,' Hermans,2 L I a t h e~,~ and Majury4 it is known that in the presence of water or of catalysts giving off water the polymerization of the caprolactam does not take place with a uniform reaction mechanism but with several reactions proceeding simultaneously. Compounds which give off water at the temperature of the polymerization, that is, at 256°C. are used as catalysts. Thus primarily hexamethylene-diammonium adipate (nylon salt) and aminocaproic acid are used. The acids and bases employed during the polymerizatjon exert only a slight catalytic effect; their role consists primarily of fixing the desired molecular weight.I n our work we investigated whether the phosphoric acid, besides its chain-closing effect, catalyzes the polymerization of the caprolactam. The water formed during the reaction 2H3PO4 HdP207 + H20 t,aking place at 250°C. is primarily expected to exert a catalytic effect. It was doubtful whether the l / l O O -l / 2 O O f l~ phosphoric acid, that is, a quantity sufficient only to stabilize the molecular weight, yields enough water for the polymerization at the velocity desirable for industrial purposes.The polymerizations were carried out in a boiler heated by diphenyl boiling at 256°C. The phosphoric acid was added to carefully distilled and recrystallized caprolactam. The polymerization was carried out under an atmosphere of purified and dried nitrogen gas. The progress of the polymerization was folloived by removing an aliquot from the polymerizing apparatus from time to time. The polymer samples were processed in the n-ay usual in the technicaI literature.The progress of the polymerization is shown in Figure 1. On the basis of the trend and shape of the curve it can be seeii that the phosphoric acid exerts a considerable catalytic effect.The correlation between conversion and time is shown in Table I. Careful examination of the character of the tabulated data and the per-'795

SYNOPSISFibers from mixtures of two polypropylene types were produced with the same conditions. The polymer base was a normal fiber grade polymer to which a high molecular weight polypropylene was added in amounts of 25,50, and 75%. The extensibility of the fibers changed considerably by increasing the high polymer amount. The tensile properties were measured and compared with measured structural properties, such as crystallinity, crystalline particle size, amorphous orientation, amorphous region derived from small and wide-angle X-ray scattering. New terms, the specific amorphous orientation and the structural deformability index, were proposed, and it was shown that the tensile properties, i.e., strength, elongation at break, initial modulus and sonic modulus, are in very good correlation with them.

ZUSAMMENFASSUNG:Wir untersuchten die Caprolactampolymerisation mit Caprolactam-hydrochlorid mit Hilfe der dilatometrischen Methode. Auf Grund des Zusammenhangs zwischen Geschwiudigkeitsmaximum und Katalysatoranfangskonzentration sollten beide funktionelle Gruppen der bei der Initiierungsreaktion entstandenen Produkte am Kettenwachstum teilnehmen. Nach dern Maximalwert zu Reaktionsbeginn sinkt die Polymerisationsgeschwindigkeit bis zu einem Minimum und wachst dann wieder bis zum Erreichen eines stationiren Wertes. Der Gesamtcharakter der kinetischen Kurven deutet daraufhin, daI3 der Polymerisationsmechanismus verwickelt ist und sich wahrscheinlich das Kettenwachstum nicht auf dern Wege ein und desselben Elementarschrittes abspielt. _ j 1 1 O L J HCl O~N-CO(CH,),NHCO(CH,),NHCO(CH,),NH,~HCl + O b N H ' (cH2)5 J I (CHA J ' (CHZ),

ZUSAMMENFASSUNG:Wir untersuchten die Polymerisation des Caprolactams mit Benzylamin-hydrochlorid auf dilatometrischem Wege. Der Charakter der kinetischen Kurven weist darauf hin, daB eine analoge Veranderung der Aktivitat des katalytischen Systems zu beobachten ist wie mit Caprolactam-hy drochlorid als Katalysator. Dies wird mit einer Verandemng der Bindungsweise der Salzsaure wahrend der Polymerisation erklirt. Die Analyae des Anfangsabschnittes der Polymerisation lafit darauf schliefien, daB sich als erster Schritt die Reaktion des Benz3tamin-hydrochlorids zu Amin und Caprolactam-hydrochlorid abspielt. SUMMARY:The caprolactam polymerization was investigated using benzylamine hydrochloride as catalyst. The character of the kinetic curves indicates the same changes in the activity of the catalytic system as with caprolactam hydrochloride as catalyst. This observation is explained with changes in the neutralization index during polymerization. The examination of the first par1 of the polymerization reaction indicates that the starting step is the reaction of benzylamine hydrochloride to free amine and caprolactam hydrochloride.