Nucleation, Melting Behaviour and Mechanical Properties of Poly(L-lactic acid) Affected by The Addition of N, N’-Bis(benzoyl) Suberic Acid Dihydrazide

Anew category of nucleating agent for poly(L-lactic acid) (PLLA) was developed. An organic nucleating agent; N,N’-bis(benzoyl) suberic acid dihydrazide (NA) was synthesized from benzoyl hydrazine and suberoyl chloride which was deprived from suberic acid via acylation. The nucleation, melting behaviour and mechanical properties of the PLLA containing NA were investigated. NA showed excellent nucleating effects on PLLA crystallization. Compared to the neat PLLA, with the addition of 0.8 % NA, the crystallization temperature (To) increase from 105.88 °C to 125.57 °C and the crystallization enthalpy(ΔHc) increase from 1.379 J g–1 to 31.63 J g–1 at a cooling rate of 1 °C min–1 from melt. In the presence of NA, the melting behaviour of PLLA was affected significantly, and a double-melting peak resulted during melting-recrystallization. The tensile strengths and tensile modulus increase with the increase ofNAcontent and possesses a maximum value for the criticalNAloading of 0.8 %. However, the elongations at break of the samples decreased significantly.Keywords: Poly (L-lactic acid), crystallization, melting behaviour, benzoyl hydrazin