Supermolecular structures obtained in systems polyethylene–low molecular solvent on cooling

Abstract

Some peculiarities of the influence of the phase state of systems polyethylenelow molecular solvent on tlie morphology of the supermolecular structure of polyethylene were eslablished. With equal concentrations and almost equal crystallization temperatures it is possible to obtain Iletlritcs a n d banded spherulites depending o n the phase state determined by the phase diagram. I n Systemen aus Polyethylen und niederrnolekularen Losungstti itteln erhaltene ubermolekulare StrukturenEinige Besonderheiten des Einflusses des Phasenzustandes von Systemen aus Polyethylen und niederrnolekularen Losungsmitteln auf die Morphologie der ubermolekularen Struktur des Polyethylens werden dargelegt. Bei gleicher Konzentration und etwa gleichen Kristallisationstemperature11 ist es moglich, in Abhangigkeit von dem durch das Phasendiagramni bestimmten Phasenzustand Hedritc uud gebanderte Spharolithe zu erhalten.

Pecularities of the thermomechanical behaviour of ultra-high molecular weight linear polyethylene and its blends with linear polyethylene of normal molecular weight

“…The ascending parts of the deformation had an increasing amplitude and changed to irreversible plastic deformations. These data correlate very well with our previous microscope, X-ray, thermal and rheological studies [1,3,9] and can be explained by the presence of a physical network of entangled molecules which, by structurizing the polymer in general, ensure a considerable hardness, opposing the outer load within the range Trm M -TL. The TM-curve at constant load of UHMWPE tablet, preheated up to 150 ~ without load and then cooled, retained the presence of high-elastic state within the range 140 ~ ~ When the UHMWPE tablet was preheated up to 210 ~ without load, the shape of the TM-curve has changed.…”

“…The way of production of powdered nascent polyethylenes is described in [1,3]. The reeking and flow temperatures, determined by means of polarization microscope "ReichertZetopan" and by means of DSC [9] are as follows:…”

“…Consequently, it could be considered that the flow of UHMWPE above 190 ~ is caused by a measurable break of the physical network by the disentangling and probably breaking of a part of the tie molecules. It is probably not connected with a high decrease of the molecular mass of the polymer (Is = 0 g/10 min even at 260 ~ and 21.6 kg) [3]. The consequent cooling from 210 ~ to room temperature leads to the formation of a structure with an increased thermomechanical compliance.…”

“…It is established that the UHMWPE possess extremely good physico-mechanical properties, but their processing is made considerably difficult by the high viscosity of their melts [2]. In a previous work we have shown the flow increase of UHMWPE through its mixing with high density polyethylene of normal molecular weight (NMWPE), obtained by means of a standard Ziegler system [3]. The blends show a significant improvement of the physico-mechanical properties of NMWPE [4].…”

Structure and physicomechanical properties of high density polyethylene filled during polymerization

“…The monotonous colouring of the polymer layer depending on its position towards the direction of the gypsum plate shows that the polymeric envelope consists of lamellar crystallites which are oriented in a definite way towards the surfaces of the filler particle [13]. When the microscope plate is turned by go", the colours remain the same.…”