▁processing ▁and ▁use ▁of ▁rub bers , ▁pl ast ics , ▁and ▁fib ers . ▁Pol ym ers ▁const itute ▁the ▁basic ▁materials ▁of ▁the ▁rub ber ▁and ▁pl astic ▁indust ries ▁and ▁are ▁of ▁vital ▁importance ▁to ▁the ▁text ile , ▁pet role um , ▁autom obile , ▁paper , ▁and ▁ph arma ce ut ical ▁indust ries . ▁Their ▁vis co el astic ▁properties ▁determine ▁the ▁mechanical ▁performance ▁of ▁the ▁final ▁products ▁of ▁these ▁indust ries , ▁and ▁also ▁the ▁success ▁of ▁processing ▁methods ▁at ▁intermediate ▁stages ▁of ▁production . ▁ ▁In ▁vis co el astic ▁materials , ▁such ▁as ▁most ▁polym ers ▁and ▁pl ast ics , ▁the ▁presence ▁of ▁liquid - like ▁behaviour ▁depends ▁on ▁the ▁properties ▁of ▁ ▁and ▁so ▁var ies ▁with ▁rate ▁of ▁applied ▁load , ▁i . e ., ▁how ▁quickly ▁a ▁force ▁is ▁applied . ▁The ▁sil ic one ▁to y ▁' S illy ▁Put ty ' ▁behav es ▁quite ▁differently ▁depending ▁on ▁the ▁time ▁rate ▁of ▁applying ▁a ▁force . ▁P ull ▁on ▁it ▁slowly ▁and ▁it ▁exhib its ▁continuous ▁flow , ▁similar ▁to ▁that ▁ev iden ced ▁in ▁a ▁highly ▁vis c ous ▁liquid . ▁Alternatively , ▁when ▁hit ▁hard ▁and ▁directly , ▁it ▁sh at ters ▁like ▁a ▁sil icate ▁glass . ▁ ▁In ▁addition , ▁conventional ▁rub ber ▁under go es ▁a ▁glass ▁transition ▁( o ften ▁called ▁a ▁rub ber - glass ▁transition ). ▁E . g . ▁The ▁Space ▁Sh utt le ▁Ch allen ger ▁dis aster ▁was