High-density polyethylene method

High Density Polyethylene. High density polyethylene (HDPE), 0.94—0.97 g/cm, is a thermoplastic prepared commercially by two catalytic methods. In one, coordination catalysts are prepared from an aluminum alkyl and titanium tetrachloride in heptane. The other method uses metal oxide catalysts supported on a carrier (see Catalysis). 

Solution blending Polar as well as nonpolar solvents can be used in this method. The polymer is solubilized in a proper solvent and then mixed with the filler dispersion. In solution, the chains are well separated and easily enter the galleries or the layers of the fillers. After the clay gets dispersed and exfoliated, the solvent is evaporated usually under vacuum. High-density polyethylene [24], polyimide (PI) [25], and nematic hquid crystal [26] polymers have been synthesized by this method. The schematic presentation is given in Scheme 2.2. 

Chimassorb 944 Determination in Polypropylene, High Density Polyethylene (HDPE) and Low Density Polyethylene (LDPE) by the Total Nitrogen Content Analytical Method, Code No. KC65/1, Ciba-Geigy, Basel (1980). 

A wide variety of methodologies have been employed for the analysis of antioxidants in polymers and some standard methods are available. For high-density polyethylene ASTM method D5524 (ASTM International) — Determination of phenolic antioxidants in high-density polyethylene, describes a method whereby the sample is ground to a small particle size and then extracted by refluxing with cyclohexane. The cyclohexane extract is then examined by reverse-phase HPLC with UV detection. 

The process developed at CPRR is said to be similar in its layout to those used in private industry. Most plastic reclamation systems are designed to work with rigid containers, such as PET beverage bottles, and HDPE milk or household product containers, because they are currently the easiest postconsumer items to collect and sort. PET beverage bottles are actually not one, but several materials a PET body (clear or green), a pigmented high-density polyethylene (HDPE) base cup, aluminum cap, label, and adhesives. To separate these components, either a dry or wet separation method based on one or more of the different physical properties of the materials can be used. 

Calibration. The accepted method of calibrating a GPC system was used. Narrow molecular-weight distribution high-density polyethylene polymers were characterized by light scattering, osmometry, and sedi-... 

One of the advantages of the FTIR spectrometer is the facility of sample preparation procedure. It is possible to press powder into pellet. In this method, different diluents (matrixes) can be selected for several applications. For mid-IR frequency range, KBr, KC1, or diamond dust can be used. For far-infrared testing, high-density polyethylene (HDPE) or diamond dust is suitable. For near-infrared analysis, Csl or KBr can be selected or mulls may be used as alternatives to pellets. The sample... 

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). 

In this study, Raman spectroscopy and pattern-recognition techniques were used to develop a potential method to differentiate common household plastics by type [87-89], which is crucial to ensure the economic viability of recycling. The test data consisted of 188 Raman spectra of six common household plastics high-density polyethylene (HDPE), low-density polyethylene (LDPE), polyethylene terephthalate (PET), polypropylene (PP), polystyrene (PS), and polyvinylchloride... 

A test set of 6 to 13 aroma compound partition coefficients between different food contact polymers (low density polyethylene (LDPE), high density polyethylene (HDPE) polypropylene (PP), polyethylene terephthalate (PET), polyamide (PA)) and different food simulant phases (water, ethanol, aqueous ethanol/water mixtures, methanol, 1-propanol) were taken from the literature (Koszinowski and Piringer, 1989, Baner, 1992, Franz, 1990, Koszinowski, 1986, Franz, 1991, Baner, 1993, Piringer, 1992). Table 4-2 shows the test set of 13 different aroma compounds, with their properties and their structures. The experimental data were compared to estimations using different estimation methods of UNIFAC-FV, GCFLORY (1990), GCFLORY (1994) and ELBRO-FV. 

Barbalata, A. Bohossian, T. Prochazka, K. Delmas, G., "Characterization of the Molecular Weight Distribution of High- Density Polyethylene by a New Method Using Turbidity at a Lower Critical Solution Temperature," Macromolecules, 21, 3186 (1988). 

Material abbreviations include PP = polypropylene PVC = poly(vinyl chloride) HDPE = high-density polyethylene PC = polycarbonate PS = polystyrene PET = polyethylene terephthalate. Method performance data provided in this reference. 

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