On December 25, 2025, Medical Device Innovation Workshop released a relevant research interpretation, revealing the significant impact of crystallinity on polymer properties. The same monomer can form crystalline or amorphous materials through different polymerization or molding processes, which have similar chemical structures but distinct performance.
    In terms of mechanical properties, crystallinity works together with the glass transition temperature. Above the glass transition temperature, increased crystallinity enhances tensile strength and reduces creep; below it, the material becomes brittle. Data shows that when crystallinity increases from 65% to 95%, the tensile strength rises from 1.4MPa to 40MPa, and the elongation at break decreases from 500% to 20%. Density increases with crystallinity. Crystalline polymers are usually opaque due to the refractive index difference between crystalline and amorphous regions, but they can still be transparent if the crystalline region size is extremely small or the density is close to that of the amorphous region. In addition, when crystallinity exceeds 40%, the maximum service temperature of the polymer can be increased to the crystalline melting point. The higher the crystallinity, the better the solvent resistance and barrier properties. These characteristics provide important basis for material selection in fields such as medical devices.

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