Isotactic polypropylene (iPP) foils : correlation of core and shell crystallinity with mechanical properties obtained by nanoindentation

Huskić, Miroslav (avtor), Slemenik Perše, Lidija (avtor), Orel, Boris (avtor), Mihelčič, Mohor (avtor)

This study investigates the correlation between the crystallinity and mechanical properties of calendered isotactic polypropylene (iPP) foils, focusing on the influence of haul-off speed and additive type. Two groups of iPP foils produced on an industrial scale were compared: (i) foils containing 10 wt.% recycled PP at haul-off speeds of 2 and 10 m/min; and (ii) foils with different additives (neat PP, 10 wt.% recycled PP, and PP ran- dom copolymer) at a constant haul-off speed of 10 m/min. All foils exhibited a pronounced skin–core structure, with the inner surface showing higher crystallinity (up to 10%) due to slower cooling rates, as determined by Flash Differential Scanning Calorimetry (Flash DSC). Nanoindentation tests correlated these differences in crystallinity with variations in the hardness and elastic modulus across the cross-section of the foil. Higher haul-off speeds (10 m/min) resulted in increased crystallinity, a higher elastic modulus and higher hardness. Polarized optical microscopy (POM) confirmed the morphological differences and highlighted the presence of highly oriented skin layers and stratified crystalline struc- tures. These findings emphasize the significant influence of processing conditions, such as hauling speed and the addition of recycled polypropylene or a random copolymer, on the mechanical and optical properties of iPP foils. This comprehensive approach to characterizing complex structure–property relationships is valuable for optimizing the production and performance of polypropylene-based packaging foils on an industrial scale.

• Jezik: Angleški jezik
• Ključne besede: isotactic polypropylene (iPP), foils, calendering, flash differential scanning calorimetry (Flash DSC), nanoindentation, polarized optical microscopy, crystallinity, haze
• Tipologija: 1.01 - Izvirni znanstveni članek
• Organizacija: FS - Fakulteta za strojništvo
• Status publikacije: Objavljeno
• Različica publikacije: Objavljena publikacija
• Datum objave: 11.03.2025
• Leto izida: 2025
• Št. strani: 18 str.
• Številčenje: Vol. 17, no. 6, art. 736
• PID: 20.500.12556/RUL-167831
• UDK: 621
• ISSN pri članku: 2073-4360
• DOI: 10.3390/polym17060736
• COBISS.SI-ID: 229024771
• Datum objave v RUL: 14.03.2025

Gradivo je del revije

• Naslov: Polymers
• Skrajšan naslov: Polymers
• Založnik: MDPI
• ISSN: 2073-4360
• COBISS.SI-ID: 517951257

Licence

• Licenca: CC BY 4.0, Creative Commons Priznanje avtorstva 4.0 Mednarodna
• Povezava: http://creativecommons.org/licenses/by/4.0/deed.sl
• Opis: To je standardna licenca Creative Commons, ki daje uporabnikom največ možnosti za nadaljnjo uporabo dela, pri čemer morajo navesti avtorja.

Sekundarni jezik

• Jezik: Slovenski jezik
• Ključne besede: izotaktični polipropilen (iPP), folije, kalandriranje, hitra diferenčna dinamična kalorimetrija (Flash DSC), nanoindentacija, polarizacijska optična mikroskopija, kristaliničnost, motnost

Projekti

• Financer: ARIS - Javna agencija za znanstvenoraziskovalno in inovacijsko dejavnost Republike Slovenije
• Številka projekta: P2-0264-2020
• Naslov: Trajnostni Polimerni materiali in Tehnologije