The strongest ropes commercially available today are made from HMPE, or High Modulus PolyEthylene.  HMPE a material that is composed of extraordinarily long molecular chains of polyethylene.  Industry began using HMPE in the 1950s, and started spinning it into fibers in the 1970s.  It is very tough, with the highest impact strength of any thermoplastic presently made.  How strong is it?  With a yield strength of 2.4 GPa (348,090+ psi), it is as strong as high carbon/high strength steel.  However, because of HMPE’s extremely low density, it has a strength-to-weight ratio 8 time higher than high strength steel!  This is why plasma-based soft shackles and winch lines float… HMPE is an amazing material, used in many exotic applications such as artificial joints, body armor, and high pressure hydraulic joints and seals.  And of course synthetic line, which is used to build ASR Offroad recovery gear! 

ELASTICITY: HMPE fibers are very inelastic, they do not stretch much at all.  After a rope is braided and spliced, there is typically a "constructional stretch" as the rope is loaded past 40% MTS for the first time, which can lead to up to 5% elongation.  Once this constructional stretch has been removed, there will be virtually no stretch in an HMPE rope.   

DURABILITY: HMPE ropes are extraordinarily durable.  HMPE also has a low coefficient of friction, which means it has excellent wear properties and can have a slippery feel.  As with all rope, HMPE line can be susceptible to cutting if put under tension while on a sharp edge.  

WATER ABSORPTION: HMPE does not absorb water, and it's strength is unaffected by exposure to water.  

HEAT RESISTANCE: HMPE will start to experience a loss of strength at temperatures exceeding of 140 degrees F.  For perspective, the hottest temperature ever recorded on earth in nature was 134 degrees F in Death Valley CA in 1913.   

PLASMA: Arguably the strongest HMPE rope available is Plasma, made by Cortland.  Plasma is manufactured from strands of HMPE that have been enhanced by Cortland’s patented recrystallization process.  The Plasma® process draws the precisely twisted strand through a heated fluid filled pressurized vessel, creating a constant heat profile throughout the strand’s cross-section.  This process ensures that all filaments are drawn under the same controlled conditions, thereby enhancing the base HMPE fiber by further aligning its molecules and effectively increasing fiber strength efficiency throughout the strand.