Crystal-nuclei formation during injection-molding of poly (L-lactic acid)

被引：10

作者：

Du, Mengxue ^{[1
]}

Jariyavidyanont, Katalee ^{[1
]}

Boldt, Regine ^{[2
]}

Tariq, Muhammad ^{[3
,4
]}

Fischer, Matthieu ^{[2
]}

Spoerer, Yvonne ^{[2
]}

Kuehnert, Ines ^{[2
]}

Androsch, Rene ^{[1
]}

机构：

[1] Martin Luther Univ Halle Wittenberg, Interdisciplinary Ctr Transfer oriented Res Nat Sc, D-06099 Halle An Der Saale, Germany

[2] Leibniz Inst Polymerforschung Dresden e V, Hohe Str 6, D-01069 Dresden, Germany

[3] Martin Luther Univ Halle Wittenberg, Inst Phys, D-06099 Halle An Der Saale, Germany

[4] Univ Engn & Technol, Basic Sci Dept, Taxila 47040, Pakistan

来源：

POLYMER | 2022年 / 250卷

关键词：

Injection molding; Skin-core structure; Simulation; Crystallization; Crystal nucleation; Poly ( L -lactic acid); SHEAR-INDUCED CRYSTALLIZATION; FLOW-INDUCED CRYSTALLIZATION; MULTIPLE MELTING BEHAVIOR; MECHANICAL-PROPERTIES; POLY(L-LACTIC ACID); POLY(LACTIC ACID); NUCLEATION KINETICS; ENTHALPY RELAXATION; CHIP; PHASE;

D O I：

10.1016/j.polymer.2022.124897

中图分类号：

O63 [高分子化学（高聚物）];

学科分类号：

070305 ; 080501 ; 081704 ;

摘要：

Injection-molding of rather slow crystallizing poly (L-lactic acid) (PLLA) was analyzed regarding the formation of crystal nuclei at different distances from the skin in a standard test bar. The relative number of nuclei in the various regions of fully amorphous test bars was estimated by evaluation of the kinetics of cold-crystallization, being faster in the skin than in the core region of the component. Simulation of the cooling-rate- and shear-rateprofiles along the cross-section of the molded bar suggests that the different nuclei numbers in skin and core mainly are caused by the higher shear rate in surface-near regions, though being supercritical for shear-induced nuclei formation also in the core. The latter conclusion is derived by comparing both the cold-crystallization kinetics and semicrystalline morphology with those of non-injection molded PLLA. The simulated shear-rate data, after conversion into specific-work-of-flow data, were found significantly exceeding the critical specific work of flow for shear-induced nuclei formation, being around 25 kPa, in all regions of the component. The results of the present study successfully demonstrate that knowledge about the crystallization kinetics of the sheared and quiescent melt of PLLA can be used to predict structure formation in industrial processing.

引用

页数：12

共 96 条

[1] Effect of nucleating agents on crystallinity and properties of poly (lactic acid) (PTA) [J].