Impact toughness of CPP- and PET-Based hybrid thermoplastic laminates under edgewise charpy testing

Abstract

This study examines the Charpy impact characteristics of laminated thermoplastic composites made from cast polypropylene (CPP) and polyethylene terephthalate (PET) matrices, reinforced with glass, carbon, and hybrid fiber stacking sequences. Laminates for composite materials were produced using the process of stacking films and hot-pressing them, followed by cutting, and then tested according to ISO 179-1 directives. The Charpy impact test was performed on five specimens for each configuration to measure both impact energy and toughness. The data show that both the matrix’s plasticity and the stacking sequence significantly influence the impact response. CPP composites displayed the best toughness against plain configurations of 7.2 J for carbon and 5.4 J for glass, while the hybrids reached up to 7.26 J for glass-carbon-glass and 6.65 J for carbon-glass-carbon. PET composites carried less toughness in standard configurations of 4.5 J for both carbon and glass, while the hybrid carbon-glass-carbon configuration improved toughness to 7.45 J. The CPP_GCG laminate absorbed about 86% more energy than the PET_G, while CPP composites absorbed 30-35% more than PET composites for all the studied stacking structures. The fractography of specimens confirmed the occurrence of ductile fracture for the CPP composites and brittle failure for the PET composites. The data demonstrate the effectiveness of combining a ductile matrix with hybrid stacking structures to elevate the toughness against impacts, as well as the tolerance to damages for laminated composites.

Keywords

• Charpy impact test
• Fiber-reinforced thermoplastics
• Impact toughness
• Hybrid composites
• Absorbed energy

Edgewise charpy testi altinda CPP ve PET bazlı hibrit termoplastik laminatların darbe dayanıklılığı

Öz

Bu çalışmada, cam, karbon ve hibrit elyaf istifleme dizileriyle güçlendirilmiş döküm polipropilen (CPP) ve polietilen tereftalat (PET) matrislerden yapılmış lamine termoplastik kompozitlerin Charpy darbe karakteristikleri incelenmektedir. Kompozit malzemeler için laminatlar, filmlerin istiflenmesi ve sıcak preslenmesi, ardından kesilmesi ve ardından ISO 179-1 direktiflerine göre test edilmesi işlemi kullanılarak üretilmiştir. Charpy darbesi, hem darbe enerjisi hem de tokluk ölçümleri için her konfigürasyondaki beş numune üzerinde gerçekleştirildi. Veriler, hem matris plastisitesinin hem de istifleme dizisinin darbe tepkisini büyük ölçüde etkilediğini göstermektedir. CPP kompozitleri, karbon için 7.2 J ve cam için 5.4 J'lik düz konfigürasyonlara karşı en iyi tokluğu gösterirken, hibritler cam-karbon-cam için 7.26 J ve karbon-cam-karbon için 6.65 J'ye ulaşmıştır. PET kompozitler, hem karbon hem de cam için 4.5 J'lik standart konfigürasyonlarda daha az tokluk taşırken, hibrit karbon-cam-karbon konfigürasyonu tokluğu 7.45 J'ye çıkardı. CPP_GCG laminatı, PET_G'den yaklaşık %86 daha fazla enerji emerken, CPP kompozitleri incelenen tüm istifleme yapıları için PET kompozitlerinden %30-35 daha fazla enerji emdi. Numunelerin fraktografisi, CPP kompozitleri için sünek kırılmanın ve PET kompozitleri için gevrek kırılmanın meydana geldiğini doğruladı. Veriler, darbelere karşı tokluğu ve lamine kompozitler için hasar toleransını artırmak için sünek bir matrisi hibrit istifleme yapılarıyla birleştirmenin etkinliğini göstermektedir.

Anahtar Kelimeler

• Charpy darbe testi
• Elyaf takviyeli termoplastikler
• Darbe tokluğu
• Hibrit kompozitler
• Emilen enerji

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