Polystyrene/polyethylene oxide copolymer for enhancing water vapor permeability in thermoplastic foam

摘要

Polymeric foam and polymeric foam products that contain a foamable polymer material, at least one blowing agent, a polystyrene/polyethylene oxide copolymer, and optionally, an infrared attenuating agent, are provided. In exemplary embodiments, the blowing agent includes at least one hydrofluorocarbon blowing agent. The maleic anhydride-styrene copolymer grafted with polyethylene oxide provides a water vapor permeability of 1.1 perm inch or greater in the extruded foam product without detrimentally affecting physical or thermal properties of the product. Additionally, the copolymer of maleic anhydride-styrene grafted with polyethylene oxide has a positive affect on the processability of the blowing agent(s) in the composition by both widening the process window and enhancing the solubility of the blowing agent in the polymer melt. Thus, the polystyrene/polyethylene oxide copolymer present in the inventive composition acts as a cell enlarger, a plasticizer, and a processing aid. A method of forming an extruded foam product is also provided.

主权项

1. A composition for forming a closed cell, rigid thermoplastic polymer foam comprising:
polystyrene; at least one blowing agent; and a polystyrene/polyethylene oxide copolymer having the formulawhere X is from 100 to 2,500, Y is from 20 to 500, Z is from 5 to 50, and R is C1-C25,
wherein said composition forms a foamed product that has a water vapor permeability from 1.1 perm inch to about 1.5 perm inch; and wherein the polystyrene/polyethylene oxide copolymer is present in an amount from greater than 0.5% to about 5% by weight of the total dry components of the composition.