Polyethylene length-temperature

A more detailed study of the effect of pH, chain length of the polyethylene glycol, temperature, and concentration in solution has also been attempted, particularly with a view of studying ion conduction in a solid film of these complexes [85]. 

Polyethylene is injected into a mould at a temperature of 170°C and a pressure of 100 MN/m. If the mould cavity has the form of a long channel with a rectangular cross-section 6 mm X 1 mm deep, estimate the length of the flow path after 1 second. The flow may be assumed to be isothermal and over the range of shear rates experienced (10 -10 s ) the material may be considered to be a power law fluid. 

A lace of polyethylene is extruded with a diameter of 3 mm and a temperature of 190°C. If its centre-line must be cooled to 70°C before it can be granulated effectively, calculate the required length of the water bath if the water temperature is 20°C. The haul-off speed is 0.4 tn/s and it may be assumed that the heat transfer from the plastic to the water is by conduction only. 

Both investigated systems are melts of polybead chains at a temperature of 473 K. Configurations of chain length ranging from 24 beads to 100 beads at a density of 0.75 g/cm3 (this corresponds to a comparable real system of polyethylene at a pressure of 1 bar) have been successfully embedded. The hard-sphere radius was 2.2 A, corresponding approximately to a van-der-Waals ra-... 

Boothroyd et al. [74] recently determined the temperature dependence of the Kuhn length for polyethylene with the aid of small-angle neutron scattering. In the temperature range between 100 and 200°C, dlnC /dT = - 1.1 x 10 3 K 1... 

Figure 15 Morphological map of linear polyethylene fractions. Plot of molecular weight against crystallization temperature. The types of supermolecular structures are represented by symbols. Patterns a, b and c represent spherulitic structures with deteriorating order from a to c. Patterns g and d represent rods or sheet-like structures whose breadth is comparable to their length g or display a different aspect ratio d. Pattern h represents randomly oriented lamellae. Neither h nor g patterns have azimuthal dependence of the scattering. Reproduced with permission from Ref. [223]. Copyright 1981 American Chemical Society. (See Ref. [223] for full details.) Note the pattern a is actually located as o in the figure this was an error on the original.

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