Yenziwe kwizinto ezithambileyo (i-PP copolymer) oku kwenza ukuba iphantse ingaphuki.Nangona ebusika obubandayo izinto zihlala zomelele kwaye ziguquguquka.Esi sondlo sinokuvalwa ngokukhawuleza okusebenzayo ekulula ukusitshixa ukuthintela ukuchitheka ngengozi.