Polyethylene melt index

For one thing, remembering again the fact that an interval from p — 3normal distribution, the figure 6a is sometimes stated as the process capability. This usage would say that in the context of the polyethylene melt index example of Table 5.4 the a = 12.1 figure from (5-10) implies a melt index process capability... 

Hjrpalon type Chlorine, % Sulfur, % Mooney viscosity Polyethylene Melt index Stress Exp. ... 

In terms of ESCR, the time to failure improves significantly as density is lowered from 0.96 g/cc to 0.95 g/cc at the same molecular weight, but there is also an additional improvement in ESCR time to failure as the molecular weight is increased, as shown by a decrease in the polyethylene Melt Index. Table 5.16 shows the time to failure (represented as 50% failure in the number of test samples) as Melt Index changes from 6.5 to 0.3 at a density of 0.95 g/cc. 

Z Dark, W. A., Determination of polyethylene melt index from GPC data, UqM Chromatography cf Polymers and Related Materials HI (J. Cazes, ed. Marcel Dekker, New York (1981)... 

Rachtanapun, P, S. E. M. Selke, and L. M. Matuana. 2004. Effect of the high-density polyethylene melt index on the microcellular foaming of high-density polyethylene/polypropyl-ene blends. JAppl Polym Sci 93 364—71. 

Prediction of Polyethylene Melt Index and Molecular Weight Distribution Using a... 

PREDICTION OF POLYETHYLENE MELT INDEX AND MOLECULAR WEIGHT DISTRIBUTION... 

Polyethylene and polypropylene are semitransparent plastics made by polymerization. They are produced from ethylene and propylene in a variety of grades. Their mechanical properties are determined mainly by density (degree of crystallinity) and molecular weight, characterized by the Melt Index (MI). 

Polythiosemicarbazide disulfide is the most efficient aliphatic polyamine disulfide for inhibiting the thermal oxidative breakdown of polypropylene, while polyimi-noaniline disulfide and polydiiminodiphenyloxide disulfide (Fig. 3) are the most efficient aromatic polyamine disulfides. In contrast to polyethylene, the thermal oxidative breakdown period increases as the concentration increases (Fig. 4), Depending on the concentration, the flow-melt index at 230°C increases at a lower rate than in the case of commercial stabilizer Santanox (Table 2)-... 

The melt flow rate of a polymer is the weight of polymer in grams that extrudes from a standard capillary die under a standard load, at a standard temperature, over a ten minute period. The term melt index is used exclusively for polyethylene melt flow rate is the preferred term for all other polymers, We measure melt flow rates using a piece of equipment called a melt indexer . The capillary dimensions, testing temperature, and load are specified for a given polymer by the National Institute for Standards and Testing. 

Polyethylene is used in extrusion and injection molding processes. When used to manufacture blown films a standard polyethylene will have a melt index of approximately 1 g/10 min, while that used for injection molding typically has a melt index of 5 to 20 g/10 min. Why are the polymers used for these two processes so different ... 

Table V compares M, M and M values for two polyethylenes analyzed by SEC in TCB solution at l45°C. Sample C is a linear low density material listed in Table 1. NBS 1 476 is low density polyethylene which is stated to be a low conversion tubular reactor product with density 0.931 gem and melt index 1.2 (11). IL and are little af fected by the existence of aggregates in these two samples but values are more severely influenced.

Ethylene Polymers. Depending on the polymerization conditions, three major types of polyethylene are manufactured low-density polyethylene (LDPE) by free-radical polymerization, linear low-density polyethylene (LLDPE) by copolymerization of ethylene with terminal olefins, and high-density polyethylene (HDPE) by coordination polymerization. The processes yield polymers with different characteristics (molecular weight, molecular weight distribution, melt index, strength, crystallinity, density, processability). 

Linear low-density polyethylene (LLDPE)440-442 is a copolymer of ethylene and a terminal alkene with improved physical properties as compared to LDPE. The practically most important copolymer is made with propylene, but 1-butene, 4-methyl-1-pentene, 1-hexene, and 1-octene are also employed.440 LLDPE is characterized by linear chains without long-chain branches. Short-chain branches result from the terminal alkene comonomer. Copolymer content and distribution as well as branch length introduced permit to control the properties of the copolymer formed. Improvement of certain physical properties (toughness, tensile strength, melt index, elongation characteristics) directly connected to the type of terminal alkene used can be achieved with copolymerization.442... 

POLYETHYLENE, A thermoplastic molding and extrusion material available in a wide range of flow rates (commonly referred to as melt index) and densities. Polyethylene offers useful properties, such as toughness at temperatures ranging from —76 to +93°C. stiffness, ranging from flexible to rigid, and excellent chemical resistance. The plastic can be fabricated by all thermoplastic processes. 

Mechanical properties of polyethylenes vary with density and melt index. Low-density polyethylenes are flexible and tough high-density products arc quite rigid and have creep resistance under load. Toughness is the primary mechanical property affected by melt index, with lower-melt-index polyethylenes having greater toughness. Under loads, polyethylene is subject to creep, stress relaxation, or a combination of both,... 

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