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Expanded polyethylene
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<h2 id="properties">Properties</h2> <p>EPE foams are low density, semi-rigid, <a href="/facts/Closed_cell_foam/kGrXWWcb">closed cell foam</a> that are generally somewhere in <a href="/facts/Stiffness/xlabLkfT">stiffness</a>/compliance between <a href="/facts/Expanded_polystyrene/dfIVntty">Expanded polystyrene</a> and <a href="/facts/Polyurethane/qNo2KSXA">Polyurethane</a>. Production of EPE foams is similar to that of expanded polystyrene, but starting with PE beads.<a class="footnote-ref" id="fnref:1" href="#fn:1"><sup>1</sup></a> Typical densities are 29 to 120 kg/m3 (49 to 202 lb/cu yd) with the lower figure being common.<a class="footnote-ref" id="fnref:2" href="#fn:2"><sup>2</sup></a> Densities as low as 14 kg/m3 (24 lb/cu yd) can be produced.<a class="footnote-ref" id="fnref:3" href="#fn:3"><sup>3</sup></a> </p><p>Base polymer for EPE foams range from <a href="/facts/Low-density_polyethylene/qK26w1dJ">Low-density polyethylene</a> (LDPE) to <a href="/facts/High-density_polyethylene/9mUm98TQ">High-density polyethylene</a> (HDPE).<a class="footnote-ref" id="fnref:4" href="#fn:4"><sup>4</sup></a> </p> <h3>Co-polymers</h3> <p>Expanded polyethylene copolymers (EPC) are also known - such as 50:50 (weight) materials with <a href="/facts/Polystyrene/dfIVntty">polystyrene</a>. Though other properties are intermediate between the two bases, toughness for the copolymer exceeds either, with good tensile and puncture resistance. It is particularly applicable for re-usable products.<a class="footnote-ref" id="fnref:5" href="#fn:5"><sup>5</sup></a> </p> <h2 id="production">Production</h2> <p>EPE foams were first manufactured in the 1970s.<a class="footnote-ref" id="fnref:6" href="#fn:6"><sup>6</sup></a> </p><p>Production of the PE beads is usually by extrusion, followed by chopping, producing a 'pellet'.<a class="footnote-ref" id="fnref:7" href="#fn:7"><sup>7</sup></a> <a href="/facts/Autoclave/bg1J3cXJ">Autoclave</a> expansion is the most common route the bead foam.<a class="footnote-ref" id="fnref:8" href="#fn:8"><sup>8</sup></a> Butane or pentane is often used as a <a href="/facts/Blowing_agent/T6JxAzVX">blowing agent</a> (before 1992 CFCs may have been used). Depending on the specific process uses the beads may be <a href="/facts/Cross-linked/zeQ9hEAA">cross-linked</a> either by electron beam irradiation (see <a href="/facts/Electron_beam_processing/dNlumRKv">Electron beam processing</a>), or by the addition of a chemical agent such as <a href="/facts/Dicumyl_peroxide/63zU9ItF">dicumyl peroxide</a>.<a class="footnote-ref" id="fnref:9" href="#fn:9"><sup>9</sup></a> </p><p>An alternate route (JSP Process) to the beads uses <a href="/facts/Carbon_dioxide/xGzpppEp">carbon dioxide</a> as a blowing agent which is impregnated into the pellets in an autoclave at a temperature close to the plastic's crystalline melting point. The pellets are foamed by "flashing" into the (lower pressure) atmosphere to expand.<a class="footnote-ref" id="fnref:10" href="#fn:10"><sup>10</sup></a> </p><p>Finally molding is done by steam chest compression molding; usually the low pressure variant of the process is used, though the high pressure variant may be used for HDPE based EPE foams.<a class="footnote-ref" id="fnref:11" href="#fn:11"><sup>11</sup></a> </p> <h2 id="uses">Uses</h2> <p>Polyethylene bead foams (including) EPE can be used to replace both <a href="/facts/Polystyrene_foam/dfIVntty">polystyrene foam</a>, and both rigid and flexible <a href="/facts/Polyurethane/qNo2KSXA">polyurethane</a>. Uses include cushioning applications, and impact absorption applications including packaging.<a class="footnote-ref" id="fnref:12" href="#fn:12"><sup>12</sup></a> </p><p>Consumption of <a href="/facts/Polyethylene/LaaAf4cn">polyethylene</a> for PE foam was estimated at 114x106 kg in 2001. The majority was used for non-crosslinked foams, but crosslinked PE foams represented a significant (~ one third) fraction of demand. Use in protective packaging represented the largest use sector for such foams.<a class="footnote-ref" id="fnref:13" href="#fn:13"><sup>13</sup></a> </p><p><a href="/facts/Gore-Tex/ST3smnuS">Gore-Tex</a> uses EPE for a waterproof, windproof and breathable fabric for <a href="/facts/Winter_clothing/LxdyxDls">winter clothing</a>. </p> <h2 id="see-also">See also</h2> <ul><li><a href="/facts/Waterproof_fabric/xGSRhVXa">Waterproof fabric</a></li></ul> <h3>Sources</h3> <ul><li>Mills, N.J. (2003), "(Report 167) Polyolefin Foams", <i>Rapra Review Reports</i>, vol. 14, no. 11, iSmithers Rapra Publishing, <a href="/facts/ISSN_(identifier)/DPAflDvU">ISSN</a> <a href="https://search.worldcat.org/issn/0889-3144">0889-3144</a></li> <li>Rosato, Dominick V.; Rosato, Donald V.; Rosato, Matthew V. (2004), <i>Plastic Product Material and Process Selection Handbook</i>, Elsevier</li> <li>Spalding, Mark A.; Chatterjee, Ananda, eds. (2017), <i>Handbook of Industrial Polyethylene and Technology: Definitive Guide to Manufacturing, Properties, Processing, Applications and Markets Set</i>, Scrivener Publishing (Wiley)</li></ul> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>Rosato, Rosato & Rosato 2004, p. 359. - Rosato, Dominick V.; Rosato, Donald V.; Rosato, Matthew V. (2004), Plastic Product Material and Process Selection Handbook, Elsevier <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>Rosato, Rosato & Rosato 2004, p. 359. - Rosato, Dominick V.; Rosato, Donald V.; Rosato, Matthew V. (2004), Plastic Product Material and Process Selection Handbook, Elsevier <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>Spalding & Chatterjee 2017, p. 639. - Spalding, Mark A.; Chatterjee, Ananda, eds. (2017), Handbook of Industrial Polyethylene and Technology: Definitive Guide to Manufacturing, Properties, Processing, Applications and Markets Set, Scrivener Publishing (Wiley) <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> <li id="fn:4"><p>Spalding & Chatterjee 2017, p. 639. - Spalding, Mark A.; Chatterjee, Ananda, eds. (2017), Handbook of Industrial Polyethylene and Technology: Definitive Guide to Manufacturing, Properties, Processing, Applications and Markets Set, Scrivener Publishing (Wiley) <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li> <li id="fn:5"><p>Rosato, Rosato & Rosato 2004, p. 359. - Rosato, Dominick V.; Rosato, Donald V.; Rosato, Matthew V. (2004), Plastic Product Material and Process Selection Handbook, Elsevier <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li> <li id="fn:6"><p>Spalding & Chatterjee 2017, p. 639. - Spalding, Mark A.; Chatterjee, Ananda, eds. (2017), Handbook of Industrial Polyethylene and Technology: Definitive Guide to Manufacturing, Properties, Processing, Applications and Markets Set, Scrivener Publishing (Wiley) <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li> <li id="fn:7"><p>Spalding & Chatterjee 2017, Fig. 21.2 p.643; pp.650-652. - Spalding, Mark A.; Chatterjee, Ananda, eds. (2017), Handbook of Industrial Polyethylene and Technology: Definitive Guide to Manufacturing, Properties, Processing, Applications and Markets Set, Scrivener Publishing (Wiley) <a href="#fnref:7" class="footnote-back-ref">↩</a></p></li> <li id="fn:8"><p>Spalding & Chatterjee 2017, p. 640. - Spalding, Mark A.; Chatterjee, Ananda, eds. (2017), Handbook of Industrial Polyethylene and Technology: Definitive Guide to Manufacturing, Properties, Processing, Applications and Markets Set, Scrivener Publishing (Wiley) <a href="#fnref:8" class="footnote-back-ref">↩</a></p></li> <li id="fn:9"><p>Spalding & Chatterjee 2017, Fig. 21.2 p.643; pp.650-652. - Spalding, Mark A.; Chatterjee, Ananda, eds. (2017), Handbook of Industrial Polyethylene and Technology: Definitive Guide to Manufacturing, Properties, Processing, Applications and Markets Set, Scrivener Publishing (Wiley) <a href="#fnref:9" class="footnote-back-ref">↩</a></p></li> <li id="fn:10"><p>Spalding & Chatterjee 2017, pp. 651–2. - Spalding, Mark A.; Chatterjee, Ananda, eds. (2017), Handbook of Industrial Polyethylene and Technology: Definitive Guide to Manufacturing, Properties, Processing, Applications and Markets Set, Scrivener Publishing (Wiley) <a href="#fnref:10" class="footnote-back-ref">↩</a></p></li> <li id="fn:11"><p>Spalding & Chatterjee 2017, pp. 645–6. - Spalding, Mark A.; Chatterjee, Ananda, eds. (2017), Handbook of Industrial Polyethylene and Technology: Definitive Guide to Manufacturing, Properties, Processing, Applications and Markets Set, Scrivener Publishing (Wiley) <a href="#fnref:11" class="footnote-back-ref">↩</a></p></li> <li id="fn:12"><p>Spalding & Chatterjee 2017, p. 640. - Spalding, Mark A.; Chatterjee, Ananda, eds. (2017), Handbook of Industrial Polyethylene and Technology: Definitive Guide to Manufacturing, Properties, Processing, Applications and Markets Set, Scrivener Publishing (Wiley) <a href="#fnref:12" class="footnote-back-ref">↩</a></p></li> <li id="fn:13"><p>Mills 2003, p. 34. - Mills, N.J. (2003), "(Report 167) Polyolefin Foams", Rapra Review Reports, vol. 14, no. 11, iSmithers Rapra Publishing, ISSN 0889-3144 <a href="https://search.worldcat.org/issn/0889-3144" target="_blank">https://search.worldcat.org/issn/0889-3144</a> <a href="#fnref:13" class="footnote-back-ref">↩</a></p></li> </ol>