Polyethylene comparison

Briggs, D., Brewis, D.M., Dahm, R.H., Fletcher, I.W. (2003) Analysis of the surface chemistry of oxidized polyethylene comparison of XPS and ToF-SIMS. Surf. Interface Anal., 35,156-167. 

Nakae M, Uehara H, Kanamoto T, Ohama T, Porter RS. Melt drawing of ultra-high molecular weight polyethylene Comparison of Ziegler- and metallocene-catalyzed reactor powders. J Polym Sci B 1999 37 1921. 

Allen, N.S., Edge, M., Holdsworth, D., Rahman, A., Catahna, F., Fontan, E., Escalona, A. M., Sibon, F.F. Ageing and spectroscopic properties of polyethylenes comparison with metallocene polymer. Polym. Degrad. Stab. 67, 57-67 (2000)... 

Gardette, M., Perthue, A., Gardette, J.L., et al. Photo-and thermal-oxidation of polyethylene Comparison of mechanisms and influence of imsaturation content Polym. Degrad. Stab. 98(11), 2383-2390 (2013)... 

The conformational characteristics of PVF are the subject of several studies (53,65). The rotational isomeric state (RIS) model has been used to calculate mean square end-to-end distance, dipole moments, and conformational entropies. C-nmr chemical shifts are in agreement with these predictions (66). The stiffness parameter (5) has been calculated (67) using the relationship between chain stiffness and cross-sectional area (68). In comparison to polyethylene, PVF has greater chain stiffness which decreases melting entropy, ie, (AS ) = 8.58 J/(molK) [2.05 cal/(molK)] versus... 

Table 10.8 Comparison oE antioxidants in polyethylene in both the absence and presence of copper powder and carbon black (data based on ICI literature). Induction time assessed from oxygen uptake measurements using a Barcroft manometer...

Figure 11.7. Comparison of oxidation rates of unstabilised polyethylene and polypropylene (After...

Whilst it is inevitable that polypropylene will be compared more frequently with polyethylene than with any other polymer its use as an injection moulding material also necessitates comparison with polystyrene and related products, cellulose acetate and cellulose acetate-butyrate, each of which has a similar rigidity. When comparisons are made it is also necessary to distinguish between conventional homopolymers and the block copolymers. A somewhat crude comparison between these different polymers is attempted in Table 11.7 but further details should be sought out from the appropriate chapters dealing with the other materials. 

Aliphatic Polyolefins other than Polyethylene, and Diene Rubbers Table 11.11 Comparison of major propenies of ethylene-based copolymers with polyethylene ... 

It is difficult to resist a comparison between the structure and properties of acetal polymers and those of polyethylene. 

Fig. 7 gives an example of such a comparison between a number of different polymer simulations and an experiment. The data contain a variety of Monte Carlo simulations employing different models, molecular dynamics simulations, as well as experimental results for polyethylene. Within the error bars this universal analysis of the diffusion constant is independent of the chemical species, be they simple computer models or real chemical materials. Thus, on this level, the simplified models are the most suitable models for investigating polymer materials. (For polymers with side branches or more complicated monomers, the situation is not that clear cut.) It also shows that the so-called entanglement length or entanglement molecular mass Mg is the universal scaling variable which allows one to compare different polymeric melts in order to interpret their viscoelastic behavior. 

FIGURE 6.4 Comparison of Shodex GPC UT column and conventional-type column. Column Left Shodex GPC UT-806M X 2, 8 mm i.d. X 300 mm X 2. Right Conventional type column X 2, 7.8 mm i.d. X 300 mm x 2. Eluent 0.1% BHT in ODCB. Flow rate 1.0 mL/min. Detector Rl, MALLS (multi-angle laser light scattering detector). Column temp. I45°C. Sample High-density polyethylene. 

COMPARISON OF FOUR COMMERCIAL LINEAR AQUEOUS SIZE EXCLUSION COLUMNS AND FOUR SETS OF COMMERCIAL POLYETHYLENE OXIDE (PEO) STANDARDS FOR AQUEOUS SIZE EXCLUSION CHROMATOGRAPHY OF POLYVINYLPYRROLIDONE AND PEO... 

Po[yamine disulphides do not inhibit peroxide vulcanization of polyethylene, are stable in air up to 300-350°C, exhibit good compatibility and show no sweating out from the polyethylene mass. Table 8 gives the comparison between the efficiency of polyamine disulphides as thermostabilizers of cured polyethylene. 

Table 5 shows typical values for polyethylene pocket materials of course, for the various producers [60-65] they vary slightly owing to differences in formulation and process. An exact comparison is also difficult, since not all producers state tolerances respectively clarify their statistical base. 

Characteristic data for polyethylene separators in comparison with competing systems are discussed later in this section (Table 11). 

It has been found that, for a fixed mineral filler content, the viscosity of PMF-based composites increases when the coat is made of polyethylene [164, 209, 293], poly(vinyl chloride) [316] and polypropylene [326, 327], The picture was different, however, for composites based on the ethylene/vinyl acetate copolymer to which kaolin with grafted poly (vinyl acetate) was added [336]. Addition of PMF with a minimum quantity of grafted polymer results in a sharp drop of flowability (rise of viscosity), in comparison to addition of unmodified filler but with a further increase of the quantity of grafted polymer the flow gradually increases and, depending on the kaolin content and quantity of grafted polymer, may even become higher than in specimens with unmodified filler, for equal concentrations. 

Table 8-19 General comparison of metalized coextruded polyethylene and aluminum foil...

Thermogravimetric data indicate that the structure of a polymer affects stability in a neutral environment (HI). A polymer such as Teflon, with carbon-carbon bonds which are (by comparison) easily broken, and with strong carbon-fluorine bonds, is quite stable thermally. However, polyethylene, also with carbon-carbon bonds but containing carbon-hydrogen bonds which are broken relatively easily in comparison with the carbon-fluorine bond, is less stable than Teflon. In turn, polyethylene is more stable than polypropylene. This difference in stability is probably caused by tertiary carbon-hydrogen bonds in polypropylene. Polypropylene is more stable than polyisobutylene or polystyrene, which decompose principally by unzipping mechanism. 

This thermal behavior is completely opposite from the model polyethylenes that we have synthesized via ADMET. All the endotherms for the methyl-branched ADMET polyethylenes are sharp in comparison with their chain-made... 

Fig. 2. Comparison of the effects of various stress treatments upon reproductive effort in Poa annua. The intensity of each stress treatment is characterised by comparing the growth increment of stressed plants to that of control (unstressed) plants over the same experimental period. , control O, water stress (polyethylene glycol) A, mineral nutrient stress (dilute concentrations of Rorison solution) shading by neutral filters (Smit, 1980).

Acrylonitrile polymerizes in the same way as ethylene. Notice that this polymer has the same structure as polyethylene, except that a CN group is attached to every second carbon atom, so the structure is a reasonable one. A line structure of polyacrylonitrile eliminates the clutter caused by the H atoms. A ball-and-stick model of the same polymer segment is included for comparison. 

Such doubts are removed by a comparison of results for polyethylene (PE), (Fig. 5.2) obtained at such high temperatures (namely T = 509 K), that it is already possible to carry out molecular dynamics simulations for melts of (sufficiently short but chemically realistic ) chains that reach thermal equilibrium [165,168]. 

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