Amorphous polymer article
Method of producing an article comprising providing a raw material in the form of a plurality of polymer elements, the polymer elements comprising an amorphous polymer; heating the materials to a temperature above a first predetermined temperature; and compacting the material whilst above the first predetermined temperature. The first predetermined temperature is the Tg of the polymer elements, the pressure is between 100 and 200 psi; and the temperature and pressure of compaction are sufficient to soften the outer portion of the polymer elements and to cause the polymer elements to bonds to each other without melting or softening of the inner portion of polymer elements. A product is produced having a structure which comprises cores of amorphous polymer that have not been softened or melted in the method, surrounded by a mass of softened and re-hardened material which bonds the cores together.
1. A method of producing an article comprising the steps:
providing a raw material in the form of a plurality of polymer elements said polymer elements comprising an amorphous polymer;
heating said material to a temperature above a first predetermined temperature; and
compacting said material whilst above said first predetermined temperature, wherein:
said first predetermined temperature is the Tg of the polymer elements,
said pressure is between 100 and 1200 psi; and
said temperature and pressure of compaction are sufficient to soften the outer portion of the said polymer elements and to cause the said polymer elements to bond to each other without melting or softening of the inner portion of said polymer elements,
such as to produce a product the structure of which comprises cores of amorphous polymer that have not been softened or melted in the method, surrounded by a mass of softened and re-hardened material which bonds the cores together.
2. A method as claimed in claim 1 in which said temperature is between 125° C. and 190° C.
3. A method as claimed in claim 2 in which the temperature is between 135° C. and 150° C.
4. A method as claimed in claim 2 in which the temperature is between 150 and 190° C.
5. A method as claimed in claim 1 including the further steps of:
(i) raising the temperature from a first, lower, temperature to a second, higher, temperature at a first rate over a first period of time;
(ii) holding the temperature at said second temperature for a second period of time;
(iii) raising the temperature from the second temperature to a third, higher, temperature at a second rate over a third period of time;
(iv) holding the temperature at said third temperature for a further period of time; and
(v) reducing the temperature from said third temperature in accordance with a predetermined cooling strategy.
6. A method as claimed in claim 5 in which:
(i) the temperature is increased to a second temperature of 135° C. at 10° C./min;
(ii) the second temperature is held for between 5 minutes;
(iii) the temperature is increased to a third temperature of 152° C. at approximately 1° C./min;
(iv) the third temperature is held for between 5 minutes and 27 minutes; and
(v) the temperature is then returned to a lower (room) temperature in accordance with the predetermined cooling strategy.
7. A method as claimed claim 1 including the further steps of:
(i) applying the compaction pressure to the assembly;
(ii) raising the temperature from a first, lower temperature to a compaction temperature;
(iii) holding the temperature at the compaction temperature for a period of time; and
(iv) reducing the temperature from the compaction temperature in accordance with a predetermined cooling strategy.
8. A method as claimed in claim 7 in which the pressure applied in step ( 1 ) is in the region of 2.8 MPa (400 psi), the temperature is increased to 152° C. and is held for between 5 and 27 minutes before returning to the lower temperature in accordance with a predetermined cooling strategy.
9. A method as claimed in claim 1 in which the material comprises a polymer selected from the group consisting PVC, PVC/PVC and PAN.
10. A method as claimed in claim 1 in which the material comprises a combination of amorphous and crystalline polymers.
11. An article manufactured in accordance with the method of of claim 1 .
12. An article comprising a hot compaction of amorphous polymer material wherein the structure of said article comprises cores of amorphous polymer surrounded by a mass of softened and re-hardened material which bonds the cores together.
13. A method as claimed in claim 1 wherein said polymer elements comprise a molecularly oriented amorphous polymer and the said structure comprises cores of oriented amorphous polymer that have not been softened or melted in the method and retain their orientation, surrounded by a mass of softened and re-hardened material which bonds the cores together.
14. An article as claimed in claim 12 wherein the structure of the said article comprises cores of molecularly oriented amorphous polymer surrounded by a mass of softened and re-hardened material which bonds the cores together.
15. A method as claimed in claim 9 in which the material is PVC.
16. A method as claimed in claim 1 wherein the said raw material is provided in the form of a plurality of polymer elements said polymer elements consisting of an amorphous polymer.