Ballistic resistant articles comprising elongate bodies
A ballistic-resistant moulded article having a compressed stack of sheets including reinforcing elongate bodies, where at least some of the elongate bodies are polyethylene elongate bodies that have a weight average molecular weight of at least 100,000 gram/mole and a Mw/Mn ratio of at most 6. Methods for manufacturing ballistic-resistant moulded articles are also provided.
1. A ballistic-resistant molded article comprising a compressed stack of sheets comprising reinforcing elongate bodies,
wherein at least some of the elongate bodies are polyethylene elongate bodies which have a weight average molecular weight of at least 100,000 gram/mole and a Mw/Mn ratio of at most 6, and
wherein, when the polyethylene elongate bodies are tapes, at least one of the tapes has a 200/110 uniplanar orientation parameter of at least 3, and, when the polyethylene elongate bodies are fibers, at least one of the fibers has a 020 uniplanar orientation parameter of at most 55°.
2. The ballistic-resistant molded article according to claim 1 , wherein the polyethylene elongate bodies have a weight average molecular weight of at least 300,000 gram/mole.
3. The ballistic-resistant molded article according to claim 1 , wherein the elongate bodies in at least one of the sheets are unidirectionally oriented.
4. The ballistic-resistant molded article according to claim 3 , wherein a direction of the elongate bodies in a sheet is oriented in a different direction from a direction of the elongate bodies in an adjacent sheet.
5. The ballistic-resistant molded article according to claim 1 , wherein the elongate bodies are tapes.
6. The ballistic-resistant molded article according to claim 1 , wherein the elongate bodies have a tensile strength of at least 2.0 GPa, a tensile modulus of at least 80 GPa, and a tensile energy to break of at least 30 J/g.
7. The ballistic-resistant molded article according to claim 1 , further comprising a matrix material, wherein the matrix material is located in at least one sheet, between at least two sheets, or both.
8. The ballistic-resistant molded article according to claim 7 , wherein at least some of the sheets are substantially free from the matrix material and the matrix material is present between the sheets.
9. A consolidated sheet package suitable for use in the manufacture of a ballistic-resistant molded article comprising a compressed stack of sheets comprising reinforcing elongate bodies, the consolidated sheet package comprising:
2-50 sheets, each sheet comprising reinforcing elongate bodies, the direction of the elongate bodies within the sheet package being not unidirectional,
wherein at least some of the elongate bodies are polyethylene elongate bodies which have a weight average molecular weight of at least 100,000 gram/mole and a Mw/Mn ratio of at most 6, and
wherein, when the polyethylene elongate bodies are tapes, at least one of the tapes has a 200/110 uniplanar orientation parameter of at least 3, and, when the polyethylene elongate bodies are fibers, at least one of the fibers has a 020 uniplanar orientation parameter of at most 55°.
10. A method for manufacturing a ballistic-resistant molded article comprising:
providing sheets comprising reinforcing elongate bodies, stacking the sheets in such a manner that the direction of the elongate bodies within the stack is not unidirectional, and
compressing the stack under a pressure of at least 0.5 MPa,
wherein at least some of the elongate bodies are polyethylene elongate bodies which have a weight average molecular weight of at least 100,000 gram/mole and a Mw/Mn ratio of at most 6, and
wherein, when polyethylene elongate bodies are tapes, at least one of the tapes has a 200/110 uniplanar orientation parameter of at least 3, and, when the polyethylene elongate bodies are fibers, at least one of the fibers has a 020 uniplanar orientation parameter of at most 55°.
11. The method according to claim 10 , wherein the sheets are provided by providing a layer of elongate bodies and causing the elongate bodies to adhere.
12. The method according to claim 11 , wherein the elongate bodies are caused to adhere by the provision of a matrix material, wherein the matrix material is located in at least one sheet, between at least two sheets, or both.
13. The method according to claim 11 , wherein the elongate bodies are caused to adhere via compression.
14. The ballistic-resistant molded article according to claim 7 , wherein the matrix material is present in an amount of 0.2-40 wt. %, calculated on the total wt of elongate bodies and matrix material.