๐“๐จ๐๐š๐ฒ'๐ฌ ๐Š๐๐Ž๐–๐‹๐„๐ƒ๐†๐„ ๐’๐ก๐š๐ซ๐ž : ๐๐š๐ซ๐š๐ฆ๐ž๐ญ๐ž๐ซ๐ฌ ๐š๐Ÿ๐Ÿ๐ž๐œ๐ญ๐ข๐ง๐  ๐ฉ๐จ๐ฅ๐ฒ๐ฎ๐ซ๐ž๐ญ๐ก๐š๐ง๐ž ๐ฏ๐ข๐ฌ๐œ๐จ๐ž๐ฅ๐š๐ฌ๐ญ๐ข๐œ ๐Ÿ๐จ๐š๐ฆ'๐ฌ ๐ซ๐ž๐œ๐จ๐ฏ๐ž๐ซ๐ฒ ๐ญ๐ข๐ฆ๐ž

 ๐“๐จ๐๐š๐ฒ'๐ฌ ๐Š๐๐Ž๐–๐‹๐„๐ƒ๐†๐„ ๐’๐ก๐š๐ซ๐ž

"๐๐š๐ซ๐š๐ฆ๐ž๐ญ๐ž๐ซ๐ฌ ๐š๐Ÿ๐Ÿ๐ž๐œ๐ญ๐ข๐ง๐  ๐ฉ๐จ๐ฅ๐ฒ๐ฎ๐ซ๐ž๐ญ๐ก๐š๐ง๐ž ๐ฏ๐ข๐ฌ๐œ๐จ๐ž๐ฅ๐š๐ฌ๐ญ๐ข๐œ ๐Ÿ๐จ๐š๐ฆ'๐ฌ ๐ซ๐ž๐œ๐จ๐ฏ๐ž๐ซ๐ฒ ๐ญ๐ข๐ฆ๐ž"



1. Dwell time in compression state (Longer time results in slower recovery)

2. Extent of applied Compression (25-50% compression of original dimensions gives more rapid recovery than 80-90%)

3. Isocyanate Index (lower isocyanate index leads to a higher fraction of dangling chains and therefore slower recovery)

4. Dosage of mono-functional polyether polyol in the formulation (higher amount results in slower recovery-more Network Imperfection)

5. Glass transition temperature of the polymer (Tg) (higher Tg results in more viscoelastic effect)

6. Gel fraction (higher gel fraction by using more gelling catalyst results in higher isocyanate conversion and slower recovery)

7. Temperature (lower ambient temperature results in slower recovery)


Recovery of viscoelastic foams is conventionally tested by hand squeezing/pressing down the foam and then releasing the foam.


source : F Homayouni


#Polyurethane #Isocyanate #Polyol #ViscoelasticFoam #MemoryFoam

#RecoveryTime

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