Amino acids and poly(amino acids) as nucleating agents for poly(lactic acid)

In industry, rapid crystallization is often required. At present, the crystallization rate of poly(lactic acid) (PLA) is too low compared to industrial needs. In this paper, amino acids such as glycine and L-alanine and poly(amino acids) like polyglycine and poly-DL-alanine are considered as heterogeneous crystallization nucleat- ing agents. The impact of adding these bio-based addi- tives on the isothermal crystallization behavior of PLA was quantified and compared at different concentrations by using the so-called Lotz efficiency scale, which here is based on isothermal DSC measurements. In addition, rhe- ological and rheo-optical techniques were used to moni- tor the isothermal crystallization. Our results indicate that polyglycine possesses a significant nucleating ability (60.5%) which is comparable to the industrially used talc (81.1%).