Polyethylene

Polyethylene is used more than any other thermoplastic polymer. There is a wide variety of grades and formulations available that have an equally wide range of properties. In general, the outstanding characteristics of polyethylene are:

Toughness, Ease of processing, Chemical resistance, Abrasion resistance, Electrical properties, Impact resistance, Low coefficient of friction, Near-zero moisture absorption.

The three most commonly used grades of polyethylene are: Low Density, High Density and Ultra high molecular weight.
Low Density Polyethylene (LDPE)

LDPE, was the first of the polyethylene’s to be developed. It is a corrosion resistant, low density extruded material that provides low moisture permeability. LDPE has a fairly low working temperature, soft surface and low tensile strength. It is an excellent material where corrosion resistance is an important factor, but stiffness, high temperature and structural strength are not important considerations.

Features:
Lightweight, Formable, Impact Resistant, Excellent Electrical Properties, Machinable, Weldable.

Fabrication:
LDPE can be fabricated using the following techniques. Hot gas welded, Fusion and butt welded, Ultra-sonic sealed, Die cut, Vacuum formed Thermo-formed, Machined with wood or metal working tools.

Applications:
Chemical resistant tanks and containers, Food storage containers, Laboratory equipment, Disposable Thermo-formed products, Corrosion resistant work surfaces, Vacuum formed end caps and tops, Moisture barriers.
High Density Polyethylene  (HPDE)

HPDE is more rigid and harder than lower density materials. It also has a higher tensile strength, four times that of low density polyethylene, and it is three times better in compressive strength. HDPE meets FDA requirements for direct food contact applications. It also is accepted by USDA, NSF and the Canadian Department of Agriculture.

Features:
Abrasion Resistant, the extremely high molecular weight of HDPE combined with its very low coefficient of friction provides and excellent abrasion resistant product preventing gouging, scuffing and scraping.

Exceptional Impact Strength:
HDPE is one of the highest impact resistant thermoplastics available and maintains excellent machine ability and self- lubricating characteristics. Properties are maintained even at extremely low temperatures.

Chemical Resistant:
HDPE has very good chemical resistance of corrosives as well as stress cracking resistance (with the exception of strong oxidising acids at elevated temperatures). Certain hydrocarbons cause only a light surface swelling at moderate temperature.

Water Resistant:
Moisture and water (including saltwater) have no affect on HDPE. It can be used in fresh and salt water immersion applications.

Fabrication:
HDPE can be fabricated using the following techniques: Hot gas welded, Fusion and butt welded, Ultra-sonic sealed, Die cut, Machined with wood or metal working tools, Vacuum formed, Thermo-formed

Applications:
Food cutting boards, Corrosion resistant wall coverings, Pipe flanges, Lavatory partitions, Chemical Plants, Radiation shielding, Self supporting containers, Industrial tanks and sinks, Boat trailer skids.

Typical properties of HDPE           

Specific Gravity:  g/cm³    
0.955
Min/Max Service Temperature in Air  
°C   
-50 to 80
Tensile Strength: Mpa   
22
Hardness:
Rockwell M
63
Impact Resistance Charpy Notched
KJ/M²
10
Thermal elongation: mm/(m.k)  
›50
Dielectric Strength: KV/mm ›30
Surface Resistivity: Ohms >1014
Co-efficient of linear expansion
K x 10¯1 180
Food Grade: FDA Yes




Typical properties of UHMWPE           

Specific Gravity:  g/cm³    
0.93
Min/Max Service Temperature in Air  
°C   
-250 to +80
Tensile Strength: Mpa   
›20
Hardness:
Rockwell M
61
Impact Resistance Charpy Notched
KJ/M²
 ›100
Impact Resistance Charpy un-Notched KJ/M²  No break
Co-efficient of thermal expansion: m/(m.k) x 10¯6  200
Dielectric Strength: KV/mm 40
Surface Resistivity: Ohms >1x1014
Flammability UL94
HB
Food Grade: FDA Yes






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