Related Experiment Video
Updated: Sep 23, 2025

Synthesis of Programmable Main-chain Liquid-crystalline Elastomers Using a Two-stage Thiol-acrylate Reaction
Published on: January 19, 2016
Effect of stereocomplex crystal and flexible segments on the crystallization and tensile behavior of poly(l-lactide)
Xiaolu Li1, Xiuqin Zhang1, Guoming Liu2
1Beijing Key Laboratory of Clothing Materials R & D and Assessment, Beijing Engineering Research Center of Textile Nanofiber, School of Materials Science & Engineering, Beijing Institute of Fashion Technology Beijing 100029 China clyzxq@bift.edu.cn clywangrui@bift.edu.cn.
Abstract:
The effects of poly(ethylene glycol) (PEG) and/or poly(d-lactide) (PDLA) blocks on the crystallization and mechanical properties of poly(l-lactide) (PLLA) were investigated systematically via differential scanning calorimetry (DSC), polarized optical microscopy (POM), wide-angle X-ray diffraction (WAXD) and tensile testing. The structural evolution during uniaxial stretching of the obtained blends above the glass transition temperature was studied by in situ WAXD. It was observed that the stereocomplex (SC) crystals promoted the nucleation of PLLA homocrystals (α/α' crystal), and flexible PEG blocks could enhance the spherulitic growth rate. The PLLA/PDLA-PEG-PDLA had a higher elongation at break than that of PLLA/PDLA without significant loss in tensile strength and stiffness. In situ WAXD showed that the PLLA/PDLA-PEG-PDLA crystallized faster during stretching. It was shown that the incorporation of SC crystals and flexible PEG blocks could not only accelerate the crystallization but also improve the toughness of PLLA.
Related Concept Videos
Polymer Classification: Stereospecificity
Polymer Classification: Crystallinity
Crystalline domains are the regions where polymer chains are aligned in an orderly manner and held together in proximity by intermolecular forces. For example, chains in the crystalline domains of polyethylene and nylon are bound together by van der Waals...
Polymer Classification: Architecture
Types of Step-Growth Polymers: Polyesters
Polyesters are commonly prepared from terephthalic acid and ethylene glycol; the crude product is known as poly(ethylene terephthalate) or PET. However, polyesters are synthesized industrially by transesterification of dimethyl terephthalate with ethylene glycol at 150 °C. The two reactants and the...
Step-Growth Polymerization: Overview
Many natural and synthetic polymers are produced by...
Molecular Weight of Step-Growth Polymers
As the step-growth polymerization involves step-wise condensation of monomers, the molecular weight also builds up eventually. Consequently, high molecular weight polymers are obtained at the late stages of the polymerization, where 99% of monomers have been consumed.
The extent of the...

