I thought I posted the following information previously - here it is again for those who are interested. In summary Spectra fibre and Dyneema fibre (well from the two manufacturers below anyway) are both gel spun polyethylene fibre with high strength, low stretch, high abrasion and UV resistance.
Honeywell Spectra Fibre
Spectra® fiber is one of the world's strongest and lightest fibers. A bright white polyethylene, it is, pound-for-pound, fifteen times stronger than steel, more durable than polyester and has a specific strength that is 40 percent greater than aramid fiber.
Spectra® fiber a polyethylene fiber that is produced using a patented gel-spinning process. Polyethylene is a remarkably durable plastic, and scientists at Honeywell have captured the tremendous natural strength in the molecular backbone of this everyday plastic to create one of the world's strongest and lightest fibers. The gel-spinning process and subsequent drawing steps allow Spectra® fiber to have a much higher melting temperature (150°C or 300°F) than standard polyethylene.
With outstanding toughness and extraordinary visco-elastic properties, Spectra® fiber can withstand high-load strain-rate velocities. Light enough to float, it also exhibits high resistance to chemicals, water, and ultraviolet light. It has excellent vibration damping, flex fatigue and internal fiber-friction characteristics, and Spectra® fiber's low dielectric constant makes it virtually transparent to radar.
Spectra® fiber is used in numerous high-performance applications, including police and military ballistic-resistant vests, helmets and armored vehicles, as well as sailcloth, fishing lines, marine cordage, lifting slings, and cut-resistant gloves and apparel. Honeywell also converts Spectra® fiber into the Spectra Shield® family of specialty composites for armor and other applications.
DMS Dyneema
Dyneema® is an UHMwPE fiber. DSM invented it 20 years ago and it's been in production since 1990. The fiber is incredibly versatile with virtually limitless applications. The fiber is manufactured by means of a gel-spinning process that combines extreme strength with incredible softness. So what are the properties that make this fiber so special?
High strength/low weight – Dyneema® is 15 times stronger than steel, and 40% stronger than aramids on a weight-for-weight basis.
Low specific gravity (0.97) - Dyneema® floats on water and is ideal for lightweight solutions.
Excellent chemical resistance - Dyneema® is chemically inert, and independent studies have confirmed that Dyneema® performs well in dry, wet, salty and humid conditions, as well as other situations where chemicals are present.
UV resistant – Products made with Dyneema® fiber show strong resistance to photo degradation when exposed to UV light. The high UV resistance of the fiber ensures continuing high performance.
Moisture resistant - Dyneema® fiber is hydrophobic. It resists water absorption, providing an extra level of protection and durability.
High durability - Dyneema® fiber can withstand the harshest environments for a longer time. This is due to its inherent strength, and its resistance to many damaging chemical agents..
Types of Dyneema®
Dyneema® derives its enormous strength from a proprietary gel-spinning process that results in extremely long, straight polymer chains. This exceptionally strong material is available in four major types.
Dyneema® fiber, an Ultra-High Molecular Weight Polyethylene (UHMwPE)
Dyneema Purity®, a medical grade fiber
Dyneema® UD, a uni-directional sheet material for laminate composite construction
Ballistic sheet, made from (UHMWPE) tape for laminate composite construction