Linear low-density PE

As part of a multi-technique investigation (see also discussion under mid-infrared spectroscopy later), Corrales et al. [13] plotted the carbonyl index for films prepared from three grades of polyethylenes a high-density PE (HDPE), a linear low-density PE (LLDPE) and a metallocene PE (mPE) (see Figure 5). In this study, the data trend shown in Figure 5 correlated well with activation energies derived from the thermal analysis, which showed that the thermal-oxidative stability followed the order LLDPE > mPE > HDPE, whereas the trend... 

As discussed earlier under Section 2.3, Carbonyl index, in one relatively recent comparison of the photo-oxidative and thermal (oven-aged) degradation behaviour of different polyethylenes, additive free grades of a metallocene (mPE), an HDPE and a linear low-density PE (LLDPE) were analysed by a combination of mid-IR spectroscopy, TGA and CL [13]. The mid-IR... 

Commercial high density, medium density, low density and linear low density PE s (HDPE, MDPE, LDPE and LLDPE respectively) were used. Their properties are listed in Table III. ... 

The different available high pressure polymerisation processes of polyethylene (PE) yield LDPE (low density PE), LLDPE (linear low density PE) and copolymer features of the same. The various process variations have been developed during recent decades and introduced a number of well developed steps and devices to achieve safe and economical operating conditions at the very high reaction pressures of 1500 to 3000 bar. 

Linear low-density PE (LLDPE) has a density similar to LDPE, but the linearity of HDPE. Branches of LLDPE are comparatively short. None of WPC manufacturers has reported that they make composite deck boards based on LLDPE, as well as on VLDPE (very low-density PE) and ULDPE (nltra low-density PE). The two latter polyethylenes have extremely high flexibility, which wonld make them inappropriate for composite deck boards or railing systems. 

Polyethylene films for agricultural applications need to have high strength and elasticity, resistance to wind forces, and a long service life. They are mostly produced from low density PE combined with linear, low density PE and ethylene-vinyl acetate copolymer. 

Polyolefin floor coverings (PP and PE), power cables with PE coverings and HDPE pipes and wall covering materials, halogen free linear low-density PE and thermoset crosslinked polyethylene are all suggested as alternatives to PVC by Greenpeace. 

Today several basic types of PE are prepared low-density PE (LDPE) linear low-density PE (LLDPE), and high-density PE (HDPE). Representative structures are shown in Figure I, where the lines represent the stretched-out strand of backbone atoms in the polymer molecule. Figure 1 illustrates the branching and bonding in these polymers, in reality polymers are usually in an entangled and random coiled conformation. The "stretched-ouf conformation would be rare. 

MW, MW distribution and side-chain branches in PE influence its material properties, including melting point and crystallinity. Linear low-density PE is more easily processed than high-density PE due to the presence of side-chain branches. The combination of stiffness and stress-crack resistance of the material are improved by the presence of these side chains [6, 7]. To improve processing, polymers with different MW can be melt-blended, but with the resultant problems and cost. 

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