Fibers of UHMWPE and a process for producing thereof
The invention relates to a process for producing gel-spun ultra high molecular weight polyethylene (UHMWPE) fibres having high tensile strengths and improved creep rates wherein the UHMWPE used in said process is characterized by a difference in the phase angle according to Formula (1) Δδ=δ 0.001 −δ 100 of at most 42°, wherein δ 0.001 is the phase angle at an angular frequency of 0.001 rad/sec; and δ 100 is the phase angle at an angular frequency of 100 rad/sec as measured with a frequency sweep dynamic rheological technique at 150° C. on a 10% solution of UHMWPE in paraffin oil, provided that δ 100 is at most 18°. The invention further relates to gel-spun UHMWPE fibres produced thereof. The gel-spun UHMWPE fibres of the invention have a tensile strength of at least 4 GPa, and a creep rate of at most 5×10 −7 sec −1 as measured at 70° C. under a load of 600 MPa. The gel-spun UHMWPE fibres produced thereof are useful in a variety of applications, the invention relating in particular to ropes, medical devices, composite articles and ballistic-resistant articles containing said UHMWPE fibres.
1. An ultra high molecular weight polyethylene (UHMWPE) fibre having a tensile strength of at least 4 GPa and a creep rate of at most 5×10 −7 sec −1 as measured at 70° C. under a load of 600 MPa, wherein
the fibre consists of ultra high molecular weight polyethylene (UHMWPE) having a difference in phase angle Δδ of at most 42° according to Formula 1:
Δδ=δ 0.001 −δ 100 (1)
wherein
δ 0.001 is the phase angle at an angular frequency of 0.001 rad/sec; and
δ 100 is the phase angle at an angular frequency of 100 rad/sec and is at most 18°, and wherein
δ 0.001 and δ 100 are measured with a frequency sweep dynamic rheological technique at 150° C. on a 10% solution of UHMWPE in paraffin oil.
2. The fibre of claim 1 wherein the creep rate is at most 3×10 −7 sec −1 .
3. The fibre of claim 1 with a tensile strength of at least 4.5 GPa.
4. A rope comprising the fibre of claim 1 .
5. A composite article comprising the fibre of claim 1 .
6. A medical device comprising the fibre of claim 1 .
7. The medical device of claim 6 , wherein the medical device is a suture or a medical cable.
8. The fibre of claim 1 , wherein the difference in phase angle Δδ of the UHMWPE is at most 40°.