TABLE OF CONTENTS The density of PE depends on the polymerisation process used and on the thermal history of each sample (Figure 2.1 and Table 3.2). It markedly influences the properties and represents the main property used in the classification of PE grades (see previously). The density of a 100% crystalline sample is considered as 1 g/cm 3, while that of a 100% amorphous sample is 0.85 g/cm 3.
| Solvent | ? (nm) | Temperature ( C) | d n/ d c (ml/g) |
|---|---|---|---|
| 1-Chloronaphthalene | 436 | 135 | 0.215 |
| 546 | 135 | 0.192 | |
| 633 | 135 | 0.183 | |
| 1,2,4-Trichlorobenzene | 436 | 135 | 0.125 |
| 546 | 135 | 0.110 | |
| 633 | 135 | 0.107 | |
| n-Decane | 436 | 135 | 0.117 |
| 546 | 135 | 0.114 | |
| 633 | 135 | 0.112 |
Elastomer-modified, filled, or reinforced grades might have significantly higher density depending on their formulation. For example, a high-density PE (HDPE) grade with 40 wt% calcite has a density of 1400 kg/m 3, while crosslinked HDPE with 30 wt% wood flour has a density of 1032 kg/m 3. The density of LDPE filled with 50 wt% CaCO 3 is 1184 kg/m 3.
PE is a linear hydrocarbon polymer. Some grades contain short and/or long branches, and some or no unsaturation. The melting point of HDPE ranges from 120 to 130 C.
The detailed...
