Embrittlement time for

Degradable Low-Density Polyethylene (LDPE) Films. Typical xenon arc embrittlement times for unstabilized low-density polyethylene are l600-2UOO hrs. The controls chosen for this research are listed in Table II the thin LDPE garment bag embrittled in 1820 hr and the EcoPlastics LDPE control became brittle after 2075 hr xenon irradiation. The thin garment bag was not brittle, as determined by a fold test, after 18 months outdoor exposure. The Dupont "Sclair" LDPE control listed in Table II was unusual since it had short embrittlement times of 1175 hr in the Weather-Ometer and 6.5 months outdoors. This film was used as a yardstick to measure the Degradable LDPE films since a Degradable Plastic should not last more than 6 months, perhaps less, outdoors and 1200 hr in the xenon arc Weather-Ometer. 

Figure 18. Relationship between peroxide and carbonyl concentrations and embrittlement time for polypropylene. (—CD—) peroxide formation, open chamber (— —) carbonyl formation, open chamber (—A—) peroxide formation, closed chamber (— —) carbonyl formation, closed chamber.

Figure 5. Embrittlement times for 25 nm LLDPE transparent mulch film with six different Envirocare additives exposed outdoors in soil contact in Pontecchio Marconi, Italy (110 kLy yr ). Data are times (dark bars) and absorbed energy (light bars) for embrittlement.

---