Polyethylene solution-grown

Fig. 12. 50 MHz DD/MAS 13C NMR spectrum of solution-grown polyethylene with a viscosity-average molecular weight of 91,000 at room temperature. The spectrum was obtained by pulse sequence I (shown in Fig. 1) with the repetition time,t = 1,500 s...

For this cycloalkane, the Tic s of the methylene carbons in the folded sequence are estimated to be 35-39 s at room temperature and become shorter with increasing temperature [66]. Hence, the Tic s for the regularly folded methylene sequence in polyethylene, if it exists, will be appreciably shorter than 35 s at room temperature, and much shorter than ca. 220 s of the inner methylene carbons of polyethylene (cf. Table 1). Hence, if we measure the DD/CP 13C NMR spectrum of the solution-grown polyethylene sample by a single pulse sequence with a rep-... 

Fig. 12. 50 MHz DD/M AS NMR spectrum of solution-grown polyethylene with a viscosity-...

In the following figures, further experiments are linked to the annealing and recrystallization of a number of additional polymers. In Fig. 6.81 the increase of lamellar thickness is illustrated on the example of solution-grown polyethylene. The crystals were collected in dried mats. The graph on the right side allows a comparison with data on melt-crystallized and annealed polyethylene (see also Sect. 5.2). Sufficiently mobile and flexible molecules, such as polyethylene, can thicken by chain... 

A consequence of post or secondary crystallization is a thickening in the long period of polymer crystals. As already noted in Section D.lc this effect can be studied over relatively short periods of time (Le., several hundred hours) by annealing semicrystalline material. In Fig. 44 this effect is demonstrated for solution grown polyethylene single crystals. 

D. M. Sadler, Studies on the Surface of Solution Grown Polyethylene Crystals and Some Related Topics, PhD dissertation. University of Bristol, 1969. 

The component of the radius of gyration in the lamella plane was measured for solution-grown polyethylene crystals as a function of tag molecular weight. It was found that was independant of My/. The authors ascribe this to... 

Experiments on two types of materials will be presented, namely (1) a powder of solution-grown polyethylene, Sholex 6050, and (2) a urea-polyethylene inclusion complex, in which polyethylene is of the same origin. The inclusion complexes of urea and low-molecular-weight hydrocarbon molecules have been studied extensively for more than thirty years, but the urea-polyethylene complex (UPEC) was successfully prepared rather recently. We prepared the complex according to the method described by Monobe et al. 

One method of investigating molecular motion in polymer physics is the observation of the temperature dependence of the line width of broad-line NMR spectra. However, since UPEC is composed of polyethylene and urea molecules, the protons in urea molecules must be replaced by deuterons in order to observe the behavior of the polyethylene chain by proton magnetic resonance. For this purpose, deuterated urea molecules were used in the preparation of UPEC (d-UPEC). In the preparation of d-UPEC, deuterated methanol has been used as a solvent in order to prevent proton exchange. In order to compare the new data with the data of bulk polymers, solution-grown polyethylene and extended-chain crystals of polyethylene were also used in the NMR study. 

Sirota E, Herhold A (1999) Transient phase-induced nucleation. Science 283(5401 ) 529-532 Spells SJ, Sadler DM, Keller A (1980) Chain trajectory in solution grown polyethylene crystals correlation between infra-red spectroscopy and small-angle neutron scattering. Polymer 21 (10) 1121-1128... 

Figure 6.14 Friction force microscopy image of a solution grown polyethylene lamellar crystal obtained in air. Schonherr and Vancso [16]. Reproduced with permission of American Chemical Society.

Fig. 4.8 Solution-grown polyethylene single crystal, (a) Electron micrograph of a lamellar crystal (courtesy of Dr P. Allan), (b) Selected-area diffraction pattern (courtesy of Dr. l.G. Voigt-Martin). 

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