A composition and a process for straightening hair are disclosed. The process includes coating keratin fibers with a composition comprising a thermally-activated agent and a guanidine moiety containing adjuvant compound and contacting the coated keratin fibers with a heating device at a temperature of at least 185℃ for sufficient time to modify the keratin fibers. The thermally-activated agent has the general formula of Formula (I): where: A is selected from NH and O R and R’ are independently selected from H, CH3, CH2CH3,and CH2OH X and Y are independently selected from H and alkyl and n = 0, or 1, or, 2, or 3 and the adjuvant is selected from a compound containing a guanidine moiety represented by the radical:本發明揭示出一種用於直髮的組成物及方法。該方法包括以一包含熱活化試劑及含胍部分佐藥化合物的組成物塗佈角質纖維,及讓該經塗佈的角質纖維與加熱裝置在溫度至少185℃下接觸足夠的時間,以修改該角質纖維。該熱活化試劑具有式(I)之通式:其中A係選自於NH及O;R及R’係各自獨立地選自於H、CH3、CH2CH3及CH2OH;X及Y係各自獨立地選自於H及烷基;及n=0、或1、或2、或3;及該佐藥係選自於包括由下列基團表示的胍部分之化合物:
