Nws tuaj yeem suav hais tias cov txheej txheem ua tiav ntawm cov txheej txheem yas yog cov txheej txheem uas cov roj hmab thiab cov khoom sib xyaw kom sib xyaw tsawg tau yaj nrog txhua lwm yam, tab sis cov plasticizer tau txawv ntawm cov kev hais txog dav dav. Thaum lub sijhawm ua haujlwm, cov kuab tshuaj yuav yaj, thiab cov yas yuav tsum nyob hauv cov kua ntev ntev ua ntej nws muaj tshuaj lom neeg nrog cov cob. Thaum cov tshuab yas ntxiv, nws tuaj yeem nce qhov hloov pauv, yoog raws, txias txias thiab elongation. Txo qhov nyuaj, hloov pauv, iav hloov pauv qhov kub, yaj taw tes, kub muag lossis yas ntws kub [17].