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Polyethylene
Plastic
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Polyethylene plastic is the most popular polymer plastic used.
Polyethylene is known for its toughness, excellent chemical
resistance, low coefficient of friction, near-zero moisture
absorption, and light weight. Four types of polyethylene exists: Low
density, medium density, high density, and ultra-high molecular
weight (UHMW).
- Low density polyethylene has good
toughness and flexibility, low heat resistance, and clarity in
film form (linear low-density polyethylene).
- Applications include packaging
applications such as industrial bags, shrink bundling,
produce/garment bags, industrial containers and toys.
- High density polyethylene has a
higher rigidity and tensile strength. It is used in items such
as cultured marble molds, cheese molds, support bracings on golf
bags, backpacks, and structural tanks.
- UHMW has great abrasion resistance,
impact strength, chemical resistance, and a low coefficient of
friction.
- UHMW is used in conveyor wear
strips, guide rails, bearings, chute linings, paper machine
suction box covers, and parts of textile looms.
Specifications:
| |
TYPES OF POLYETHYLENE |
| Property |
Low Density |
Medium
Density |
High
Density |
UHMW |
| PHYSICAL
PROPERTIES |
| Specific gravity |
0.910-0.925 |
0.926-0.940 |
0.941-0.965 |
0.928-0.941 |
| Specific volume |
30.4-29.9 |
29.9-29.4 |
29.4-28.7 |
29.4 |
| Water absorption, 24 h, (%) |
<0.01 |
<0.01 |
<0.01 |
>0.01 |
| MECHANICAL
PROPERTIES |
| Tensile strength (psi) |
600-2,300 |
1,200-3,500 |
3,100-5,500 |
4,000-6,000 |
| Elongation (%) |
90-800 |
50-600 |
20-1,000 |
200-500 |
| Tensile modulus (10^5 psi) |
0.14-0.38 |
0.25-0.55 |
0.6-1.8 |
0.20-1.10 |
| Flexural modulus (10^5 psi) |
0.08-0.60 |
0.60-1.15 |
1.0-2.0 |
1.0-1.7 |
| Impact strength, Izod
(ft-lb/in of notch) |
No break |
0.5-16 |
0.5-20 |
No break |
| Hardness, Rockwell R |
10 |
15 |
65 |
67 |
| THERMAL
PROPERTIES |
| Thermal conductivity (10^-4
cal-cm/sec-cm^2-C) |
8.0 |
8.0-10.0 |
11.0-12.4 |
11.0 |
| Coefficient of thermal
expansion |
5.6-12.2 |
7.8-8.9 |
6.1-7.2 |
7.8 |
| Deflection temperature (F) |
|
|
At 264 psi |
90-105 |
105-120 |
110-130 |
118 |
|
At 66 psi |
100-121 |
120-165 |
140-190 |
170 |
| ELECTRICAL
PROPERTIES |
| Dielectric strength (V/mil) |
460-700 |
460-650 |
450-500 |
900 |
| Dielectric constant |
|
|
At 1 kHz |
2.25-2.35 |
2.25-2.35 |
2.25-2.30 |
2.25-2.30 |
| Dissipation factor |
|
|
At 1 kHz |
0.0002 |
0.0002 |
0.0003 |
0.0002 |
| Volume resistivity (ohm-cm)
At 73 F 50% RH |
10^15 |
10^15 |
10^15 |
10^18 |
| Arc resistance (s) |
135-160 |
200-235 |
- |
- |
| OPTICAL
PROPERTIES |
| Refractive index |
1.51 |
1.52 |
1.54 |
- |
| Transmittance (%) |
4-50 |
4-50 |
10-50 |
- |
*Information provided
by IAPD
|
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