Strong Nucleating Effect of Si-Containing Tri-Block Oligomers on Poly(Ethylene Terephthalate)

Area of Science:

• Polymer Science
• Materials Chemistry
• Nanotechnology

Background:

• Poly(ethylene terephthalate) (PET) is a widely used polymer with properties that can be modified through nucleation.
• Developing effective nucleating agents is crucial for controlling PET's crystallization behavior and enhancing its performance.
• Silane coupling agents offer potential as building blocks for novel polymer additives.

Purpose of the Study:

• To synthesize and characterize a novel tri-block oligomer nucleating agent based on a silane coupling agent for PET.
• To investigate the effect of this nucleating agent, both in its oligomeric and cross-linked forms, on the thermal and crystallization properties of PET.
• To evaluate the performance of the developed nucleating agent in improving PET's crystallinity and morphology.

Main Methods:

• Synthesis of a tri-block oligomer nucleating agent (LPOBD) using 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane, oxalic acid, and low molecular weight PET.
• Cross-linking of LPOBD with tetraethyl orthosilicate to form LPOBD-T.
• Preparation of LPOBD/PET and LPOBD-T/PET composites via melt blending.
• Analysis of thermal and crystallization behaviors using X-ray Diffraction (XRD), Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TG), and Polarized Optical Microscopy (POM).

Main Results:

• The synthesized tri-block oligomer (LPOBD) demonstrated a significant nucleation effect on PET.
• The cross-linked nucleating agent (LPOBD-T) exhibited superior crystallization performance compared to LPOBD.
• Composites with 1 wt% LPOBD-T showed a 3.3% increase in crystallinity, a 21.1 °C rise in crystallization temperature, and a 53 s reduction in crystallization time (t_1/2).
• A more uniform crystalline morphology was observed in the modified PET samples.

Conclusions:

• Tri-block oligomers synthesized from a silane coupling agent are effective nucleating agents for poly(ethylene terephthalate).
• The cross-linked form (LPOBD-T) provides enhanced nucleation efficiency and improves PET's crystallization kinetics and morphology.
• This study presents a promising approach for developing advanced nucleating agents for PET modification.