Imperial Chemical Industries Limited

Derrick S Bailey

Brian P Griffin

Frederic N Cogswell

Shaped articles are provided containing a polymer which is capable of exhibiting anisotropy in the melt characterized in that the ratio of the stiffness in any two directions at right angles in the shaped article differs by at least 10%, and preferably by at least 50%, from the ratio in the same two directions for a control sample made from a melt consisting entirely of the polymer in anisotropic form. These may be obtained by a variety of methods including disturbing the normal flow pattern of flow into a mould by including obstacles to flow in the mould, disturbing the pattern of flow by foaming in the mould, by including fillers or by using polymers capable of existing as a bi-phase anisotropic and isotropic melt and forming shaped articles in which the two-phase disposition is retained.

Shaped articles formed from polymers capable of exhibiting anisotropic

Shaped articles are provided containing a polymer which is capable of exhibiting anisotropy in the melt characterized in that the ratio of the stiffness in any two directions at right angles in the shaped article differs by at least 10%, and preferably by at least 50%, from the ratio in the same two directions for a control sample made from a melt consisting entirely of the polymer in anisotropic form. These may be obtained by a variety of methods including disturbing the normal flow pattern of flow into a mould by including obstacles to flow in the mould, disturbing the pattern of flow by foaming in the mould, by including fillers or by using polymers capable of existing as a bi-phase anisotropic and isotropic melt and forming shaped articles in which this two-phase disposition is retained.

Compositions containing a polymer of PTFE and a polymer capable of exhibiting an anisotropic melt characterized in that the compositions contain between 0.05 and 99.5% of PTFE and 0.5 to 99.95% by weight of the polymer capable of forming an anisotropic melt. The presence of a minor amount of the anisotropic melt-forming polymer, that is, from 0.5 to 50% by weight of the composition enables the processability of PTFE to be improved, even to the extent of providing an injection mouldable PTFE composition. Compositions containing 20 to 50% by weight of PTFE confer benefits on anisotropic melt-forming polymers, such as lubricity and greater versatility in fabrication operations. Concentration of 0.05 to 5.0% by weight of PTFE are particularly suitable for modifying the viscosity characteristics of the low melt viscosity anisotropic melt-forming polymers so that such anisotropic melt polymers are less subject to problems such as flashing and jetting during moulding.

Growing community of inventors

Welwyn, United Kingdom

Derrick S Bailey