| 摘要 |
A melt-processable water soluble polymer composition comprises a water soluble polymer and at least 15 wt.% of a hygroscopic salt to act as a lubricant to render the polymer extrudable and/or mouldable. Preferably, the polymer is polyvinyl alcohol and the salt is an alkaline or alkaline earth metal salt selected from sodium chloride, sodium citrate, or magnesium chloride. The salt may be in anhydrous form and may be present in an amount up to 75 wt.% of the total weight of the composition. The composition may further comprise a solvent plasticiser for the polymer, especially selected from glycerine and/or propylene glycol. The salt is typically present in an amount greater than that of the plasticiser, such as 1.25-12 to 1. The composition may be provided in the form of a powder, pellet, tablet or filament. A polymer internal lubricant comprising a blend of a hygroscopic salt and a solvent plasticiser is also disclosed. |
