The Relationship between Microstructure and Mechanical Properties of PBST Two-Component Crystalline Random Copolymers...

Area of Science:

• Materials Science
• Polymer Chemistry
• Crystallography

Background:

• The mechanical properties of two-component crystalline random copolymers are intrinsically linked to their microstructure.
• The influence of composition on crystallization behavior and crystal structure is a key factor in material performance.

Purpose of the Study:

• To investigate the impact of varying butylene terephthalate (BT) content on the crystallization behavior, crystal structure, and mechanical properties of poly (butylene succinate-co-butylene terephthalate) (PBST) random copolymers.
• To correlate microstructural changes with macroscopic mechanical performance.

Main Methods:

• Systematic synthesis of PBST random copolymers with diverse BT molar ratios.
• Comprehensive analysis using Wide-Angle X-ray Diffraction (WAXD), Small-Angle X-ray Scattering (SAXS), and Differential Scanning Calorimetry (DSC).

Main Results:

• PBST-37.5 (37.5 mol% BT) exhibited the lowest strength and highest elasticity due to inhibited two-component crystallization and imperfect crystal growth.
• PBST-32.5 (32.5 mol% BT) demonstrated higher hardness with dual poly (butylene terephthalate) (PBT) and poly (butylene succinate) (PBS) crystals.
• Copolymers with >37.5 mol% BT showed only PBT crystals, with increasing BT content leading to larger crystal size, higher crystallinity, enhanced strength, and reduced elasticity.

Conclusions:

• The mechanical properties of PBST copolymers are highly sensitive to BT content, dictating the type and perfection of crystalline phases.
• Tailoring BT composition allows for control over the balance between strength and elasticity in PBST materials.
• Understanding the interplay between composition, crystallization, and microstructure is crucial for designing advanced polymer materials.