| Number | Name | Date | Kind |
|---|---|---|---|
| 2591379 | Schradermeier | Apr 1952 | |
| 4111813 | Preus | Sep 1978 | |
| 4668201 | Stark | May 1987 | |
| 4821670 | Foxcroft | Apr 1989 | |
| 5002511 | Maki | Mar 1991 |
| Number | Date | Country |
|---|---|---|
| 0523977 | Feb 1956 | BEX |
| 0269431 | Jun 1988 | EPX |
| Entry |
|---|
| "Pelaspan Expandable Polystyrene", Catalog 171-90, Dow Chemical Company, Feb. 1958, p. 32. |