High-performance Polyethylene Fibres

1. Introduction Polyethene, polyethylene, polythene A flexible waxy translucent polyalkene thermoplastic made in a variety of ways producing a polymer of varying characteristics.

LDPE: molecular weight 50,000 - 300,000 softening temperature 110 oC relative density 0.92

HDPE: molecular weight up to 3,000,000 softening temperature 130 oC relative density 0.945- 0.96

UHMW-PE: molecular weight up to 6,000,000

low moisture absorption

low coefficient of friction

highly resistant to abrasion

self lubricating

fibre commercialized in late 1970s by DSM

2. Spinning of Polymers

Spinning: A specialized form of extrusion that uses a spinneret to manufacture multiple continuous multi filaments of polymer

Types of Spinning:

Wet Spinning

Dry Spinning

Melt Spinning

Gel Spinning

Wet Spinning:

Polymers is dissolved in solvent

Precipitation of polymer

Solidification of polymers at emergence from the spinneret

Acrylic, spandex, modacrylic,

Dry Spinning:

Polymers is dissolved in solvent

Solidification of polymer through evaporating the solvent

Acetate, triacetate, acrylic, modacrylic, spandex

Melt Spinning:Polymer is melted

Solidification of cooling after extrusion

Nylon, polyester, olefins

Gel Spinning:

Preparation of gel

At extrusion fibres are first dried and than cooled in a liquid bath

Dyneema, spectra

High-performance Polyethylene Fibres

3. Production

Polymer Preparation– UHMW-PE is synthesized based on metallocene

catalysts from monomers of ethylene (C2h4)

– HDPE molecules have 700- 1,800 monomers

– UHMW-PE molecules have 100,000-250,000 monomers

Product Types

– Powder

– Rods Sheets

– Fibres

3. Production

Gel Spinning

– HPPE are produced as Dyneema by DSM in Netherlands and Toyobo/DSM in Japan and Spectra by Honeywell in USA

– Feedstock Polymer

– Spinning Solution

– Gelation and crystallization

– Drawing

3. Production

4. Structure and Properties

Fibre Form- Produced as Multifilament Yarn (0.32-10 dpf, 5 N/tex, 120 N/tex, circular cross-section, smooth skin)

Structure and Morphology (highly crystalline > 80%, non-crystalline is an interphase form characterized by high density, orientation and restricted mobility of molecular chains.

Structure and Properties• Density 0.97-0.98 gm/cm3

Commercially Available FibresDensity(kg/m3)

Den/fil(dpf)

Tenacity(N/tex)

Modules (N/tex)

ElongationTo break (%)

DSM HPF

Dyneema SK 60 970 1 2.8 91 3.5Dyneema SK 65 970 1 3.1 97 3.6Dyneema SK 75 970 2 3.5 110 3.8

Dyneema SK 76Toyobo

970 2 3.7 120 3.8

Dyneema SK 60 970 1 2.8 91 3.5

Dyneema SK 71Honeywell

970 1 3.5 122 3.7

Spectra 900 970 10 2.6 75 3.6Spectra 1000 970 5 3.2 110 3.3Spectra 2000 970 3.5 3.4 120 2.9