Enhanced crystallization, heat resistance and transparency of poly(lactic acid) with self-assembling bis-amide nucleator

Deyu Niu; Tianfeng Shen; Pengwu Xu; Manman Yu; Tianxi Liu; Weijun Yang; Zhenyu Wang; Piming Ma

doi:10.1016/j.ijbiomac.2023.123584

Enhanced crystallization, heat resistance and transparency of poly(lactic acid) with self-assembling bis-amide nucleator

Int J Biol Macromol. 2023 Apr 15:234:123584. doi: 10.1016/j.ijbiomac.2023.123584. Epub 2023 Feb 15.

Authors

Deyu Niu¹, Tianfeng Shen¹, Pengwu Xu², Manman Yu¹, Tianxi Liu¹, Weijun Yang¹, Zhenyu Wang³, Piming Ma⁴

Affiliations

¹ The Key Laboratory of Synthetic and Biological Colloids, Ministry of Education, Jiangnan University, 1800 Lihu Road, Wuxi 214122, China.
² The Key Laboratory of Synthetic and Biological Colloids, Ministry of Education, Jiangnan University, 1800 Lihu Road, Wuxi 214122, China. Electronic address: pengwuxu@jiangnan.edu.cn.
³ Institute of Environmental Processes and Pollution control, and School of Environment and Civil Engineering, Jiangnan University, Wuxi 214122, China.
⁴ The Key Laboratory of Synthetic and Biological Colloids, Ministry of Education, Jiangnan University, 1800 Lihu Road, Wuxi 214122, China. Electronic address: p.ma@jiangnan.edu.cn.

PMID: 36796569
DOI: 10.1016/j.ijbiomac.2023.123584

Abstract

The application of poly(lactic acid) (PLA) is limited by its low crystallization rate. Conventional methods to increase crystallization rate usually result in a significant loss of transparency. In this work, a bundled bis-amide organic compound N'-(3-(hydrazinyloxy)benzoyl)-1-naphthohydrazide (HBNA) was used as a nucleator to prepare PLA/HBNA blends with enhanced crystallization, heat resistance and transparency. HBNA dissolves in PLA matrix at high temperature and self-assembles into bundle microcrystals by intermolecular hydrogen bonding at a lower temperature, which induces PLA to form ample spherulites and "shish-kebab-like" structure rapidly. The effects of HBNA assembling behavior and nucleation activity on the PLA properties and the corresponding mechanism are systematically investigated. As a result, the crystallization temperature of PLA increased from 90 °C to 123 °C by adding as low as 0.75 wt% of HBNA, and the half-crystallization time (t_1/2) at 135 °C decreased from 31.0 min to 1.5 min. More importantly, the PLA/HBNA maintains good transparency (transmittance > 75 % and haze is ca. 27 %) due to the decreased crystal size, even though the crystallinity of PLA is increased to 40 %, which also led to good heat resistance. The present work is expected to expand the application of PLA in packaging and other fields.

Keywords: Bis-amide nucleator; Crystallization; Heat resistance; Poly(lactic acid); Transparency.

MeSH terms

Amides*
Crystallization
Hot Temperature*
Polyesters / chemistry

Substances

poly(lactide)
Amides
Polyesters