Cov khoom tseem ceeb tshaj plaws ntawm cov yas thiab roj hmab yog cov yas deforms thaum nws yog deformed, thaum roj hmab deforms elastically. Hauv lwm lo lus, nws tsis yooj yim rau yas kom rov qab mus rau nws thawj lub xeev tom qab deformation, thaum roj hmab yog yooj yim dua. Elasticity ntawm cov yas yog heev me me, feem ntau tsawg dua 100%, thaum roj hmab tuaj yeem ncav cuag 1000% lossis ntau dua. Nyob rau hauv feem ntau cov txheej txheem molding, cov txheej txheem khoom ua tiav tom qab Molding txheej txheem tiav; Thaum roj hmab tseem xav tau tus txheej txheem vulcanization tom qab cov txheej txheem molding ua tiav.
Yas thiab cov roj hmab muaj cov ntaub ntawv polymer, tsuas yog muaj cov pa roj carbon thiab hydrogen, thiab qee tus muaj cov pa roj oxygen me me, thiab txhua yam, cov tshuaj lom neeg, cov leeg sulfur thiab lwm yam atoms. Lawv muaj cov khoom tshwj xeeb thiab siv tau. Nyob rau hauv chav tsev kub, yas yog khoom, heev zog, thiab tsis tuaj yeem ncab thiab deformed. Roj hmab tsis nyuaj heev, ywj, tuaj yeem ncab thiab elongated, thiab tuaj yeem rov qab mus rau nws thawj lub xeev tom qab cheem ncab. Qhov no yog vim lawv cov qauv sib txawv. Lwm qhov sib txawv yog tias cov yas tuaj yeem siv tau ntau zaus, thaum siv roj hmab tsis tuaj yeem siv ncaj qha thiab tsuas siv tau rau cov txheej txheem siv roj hmab. Cov duab ntawm cov yas ntawm ntau tshaj 100 degrees txog 200 degrees yog zoo li cov duab ntawm roj hmab ntawm 60 txog 100 degrees. Yas tsis suav nrog roj hmab.