Cellulose - Regenerated Cellulose - Supplier Data by Goodfellow

Background

All forms of cellulose degrade before they melt but natural cellulose can be regenerated by the xanthate process to manufacture fibres, commonly called rayon or viscose, and film, commonly called by its earliest brand name Cellophane®.

The latter films are plasticised by glycols and water to overcome their brittleness and are transparent, colourless and of moderate crystallinity. They were very widely used for packaging but have been substantially replaced by synthetic thermoplastics, especially polypropylene.

Cellulose has very high permeability to moisture and, especially when dry, very low permeability to permanent gases. Their moisture content varies greatly with their environment reaching approximately 50% at 100% relative humidity.

Not surprisingly, this causes many of their properties to vary considerably - so summarised values must be treated with considerable caution.

Key Properties

The key properties of cellulose are tabulated below.

Table 1. Key Properties

Chemical Resistance
Acids - dilute Good
Alkalis Good
Greases and Oils Good
Electrical Properties
Dielectric constant @1 MHz 4 (dry)
Dielectric strength ( kV.mm-1 ) 30-50 @ 1 mm
Dissipation factor @ 1 kHz 0.06
Volume resistivity ( Ohm.cm ) 1010 - 1012
Mechanical Properties
Elongation at break ( % ) 18/55
Tensile modulus ( GPa ) 5/3
Tensile strength ( MPa ) 120/55
Physical Properties
Density ( g.cm-3 ) 1.44
Limiting oxygen index ( % ) approx. 18
Water absorption - equilibrium ( % ) 50
Thermal Properties
Specific heat ( J.K-1.kg-1 ) approx. 1400
Properties Cellulose Film
Property Value
Extension to break - Longitudinal % 18
Extension to break - Transverse % 55
Permeability to Carbon Dioxide @ 25 °C x10-13 cm3.cm.cm-2.s-1.Pa-1 0.01
Permeability to Hydrogen @ 25 °C x10-13 cm3.cm.cm-2.s-1.Pa-1 0.01
Permeability to Nitrogen @ 25 °C x10-13 cm3.cm.cm-2.s-1.Pa-1 0.005
Permeability to Oxygen @ 25 °C x10-13 cm3.cm.cm-2.s-1.Pa-1 0.005
Permeability to Water @ 25 °C x10-13 cm3.cm.cm-2.s-1.Pa-1 >15,000
Tensile modulus - Longitudinal GPa 5
Tensile modulus - Transverse GPa 3
Tensile strength - Longitudinal MPa 120
Tensile strength - Transverse MPa 55
Properties Cellulose Fibre
Property Value
Material Medium tenacity rayon
Specific Modulus cN/tex 300 - 700
Coefficient of thermal expansion x10-6 K-1 approx. 80
Density g.cm-3 1.5 - 1.55
Extension to break % 20 - 40
Tenacity cN/Tex 13 - 23
Thermal Conductivity @ 23 °C W.m-1.K-1 approx. 0.06

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