High density polyethylene measurements

The underwater coincidence counter (UWCC) is a transportable system for measuring fresh MOX fuel stored under water (Eccleston et al. 1998). It is a modified version of a standard Fork detector (FDET) whereby the ionization and fission chambers have been replaced with sensitive He tubes embedded in a high-density polyethylene measurement head. The UWCC measures neutrons coming from a segment of the MOX fuel in multiplication corrected coincidence mode and provides total Pu, once the isotopics and the active fuel length are known. 

Fig. 13a. FTIR spectra taken at 300 K during elongation of a high-density polyethyloie film with light polarized alternately parallel and perpendicular to the stretching direction b Stress-strain diagrams of high-density polyethylene measured at 300 K and 343 K...

Sperling [133] has reported extensively on the determination of cadmium in seawater, as well as in other biological samples and materials. He added ammonium persulfate, which permitted charring seawater at 430 °C without loss of cadmium. For workbelow 2 pg/1 cadmium in seawater he recommended extraction of the cadmium to separate it from the matrix [126,134,135]. He found no change in the measured levels over many months when the seawater was stored in high-density polyethylene or polypropylene. 

The thermal conductivity of a section of a commercially produced high density polyethylene foam channel was measured. The walls consisted of a 6.4 mm foam core with a skin of 1.6 mm thickness on either side. Sqnares were machined from the outer surface of the channel, so that heat flow throngh the entire thickness the core pins one skin layer and the complete section conld be... 

Allyl Free Radicals. Ayscough and Evans (3) have recently studied, by ESR measurements, the types of allylic free radicals produced by gamma-irradiation of several monomeric olefins. In irradiated polyethylene the allyl free radical is quite stable, persisting for several months at room temperature (31). The presence of these allyl free radicals is most noticeable in the case of high density polyethylene, and this type of free radical is undoubtedly the cause of the slow oxidation of polyethylene at room temperature, which lasts for 40 or more days after irradiation (10). Williams and Dole (40) could observe little if any oxidation of low density polyethylene when it was exposed to air after irradiation. By oxidation we mean formation of carbonyl groups as detected by infrared absorption studies at 1725 cm"1. Parenthetically, it should be noted that adding an oxygen. molecule to a free radical produces initially another type of free radical, a peroxy free radical, but in this paper we shall not discuss free radicals of this or any other types except those of hydrocarbons. 

Very recently, flow birefringence measurements have been carried out also on polymer melts. Fig. 1.5 shows a check of eq. (1.5), as carried out in this Institute with the aid of a high density polyethylene of rather... 

Fig. 2.7. Drop off of doubled extinction angle 2"/ during stress-relaxation after cessation of steady shear flow according to Wales (59). Measurements on the melt of a high-density polyethylene (Marlex 6002) at a measurement temperature of 147° C. Shear rate of the steady shear flow q = 0.06 sec-1...

Fig. 3.8. Extinction angles % vs. reduced shear rate for solutions of a high density polyethylene fraction (Dow Chem. Corp.) in transdecalin at 160° C (75). The concentrations are indicated near the curves in g/100 cm. Open and closed symbols indicate repeat measurements. The dotted line gives the extinction angle vs. at zero concentration, as obtained by linear extrapolation at several...

For example, Figs. 2.43 and 2.44 present the measured [55] viscosity and first normal stress difference data, respectively, for three blow molding grade high density polyethylenes along with a fit obtained from the Papanastasiou-Scriven-Macosko [59] form of the K-BKZ equation. A memory function with a relaxation spectrum of 8 relaxation times was used. 

Figure 2.44 Measured and predicted first normal stress difference for various high density polyethylene resins at 170° C.

High Density Polyethylene - [Both regular and high molecular weight (HMW)]. The time to increase in torque at 220°C. by the Brabender Plasticorder was determined as a measure of crosslinking. Yellowness Index after the Brabender test at 220°C. and after the first extrusion at 260°C. were also performed. 

Composite formulations were prepared as follows The straw samples as received from INEEL were ground to 0.69 mm in a hammer mill and oven dried to 1.1% moisture. The dried straw samples were then blended with various amounts of high-density polyethylene (HDPE), lubricants, and maleated polyethylene blends (MAPE) (see Table 2). The mixed formulations were then extruded with a 35-mm Cincinnati Milacron Model CMT 35 counterrotating conical twin screw extruder (Cincinnati Milacron, Batavia, OH), which produced a 9.525 x 38.1 mm2 solid cross-section. Flexural strength, density, and water sorption were measured for the extruded samples according to ASTM Standard Methods (13,14). 

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