A unique set of double-edge notched tension specimens of a Polyethylene Terephthalate Glycol-modi¿ed ¿lm was tested in mode I, plane stress. The load was registered on a universal testing machine. The displacements, ligament lengths, and video frames were recorded by a Digital Image Correlation system. With these registered data, the essential work of fracture, J-integral, and crack tip opening displacement (CTOD) fracture concepts have been applied. The onset of crack initiation was through a complete yielded ligament. The analysis showed that the intrinsic speci¿c work of fracture, we, is the speci¿c energy just up to crack initiation, which is an initiation value. we has both a coincident value and the same con-ceptual meaning as Jo, the J-integral at the onset of crack initiation. The relationship between Jo and CTOD is also determined. The in¿uence on the notch quality when the specimens were sharpened by two different procedures, femtosecond laser ablation and razor blade sliding, was analysed in detail.Peer ReviewedPostprint (author's final draft
Poly (Lactic Acid) (PLA)/Ground Tire Rubber (GTR) blends using Dicumyl peroxide (DCP) as a crosslinking agent were prepared with the following aims: propose a new route to recycle wastes rubber from the automotive industry and improve the toughness and impact strength of the inherently brittle bio-based PLA. The GTR were subjected to two types of grinding process (cryo- and dry ambient grinding). Swelling measurements revealed the grinding to be associated with a mechanical damage of the rubber chains, independently on the type of grinding or on the GTR size (from <400 µm to <63 µm). Moreover, the finest GTR contains the largest amount of reinforcing elements (carbon black, clay) that can be advantageously used in PLA/GTR blends. Indeed, the use of the finest cryo-grinded GTR in the presence of DCP showed the least decrease of the tensile strength (−30%); maintenance of the tensile modulus and the largest improvement of the strain at break (+80%), energy at break (+60%) and impact strength (+90%) as compared to the neat PLA. The results were attributed to the good dispersion of both fine GTR and clay particles into the PLA matrix. Moreover, a possible re-crosslinking of the GTR particles and/or co-crosslinking at PLA/GTR interface in presence of DCP is expected to contribute to such improved ductility and impact strength.
Double edge notched tension (DENT) specimens of a polyethylene terephthalate (PET) film were tested in an universal testing machine, measuring the displacements and the ligament lengths with a digital image correlation (DIC) system. With these data the essential work of fracture (EWF), crack tip opening displacement (CTOD), and the J-integral fracture methods were compared. The specimens were tested in mode I under plane stress conditions, verifying that the crack always propagated through a fully yielded ligament. It has been proved that we, the specific essential work of fracture was the specific energy just up to crack initiation and has the same value that J-integral at crack initiation, Jo. The relationship of these parameters with the CTOD was also shown. The influence of the notch quality on the fracture behaviour when the specimens were sharpened by two different methods, femtosecond laser ablation or by razor blade sliding, has also been analysed in detaiPeer ReviewedPostprint (author's final draft
PLA/natural rubber (NR)/wastes tire rubber (GTR) were dynamically vulcanizing using dicumyl peroxide (DCP). Swelling, dissolution, and electron microscopy revealed that the unvulcanized and weekly vulcanized blends (DCP < 3 wt%) show a continuous rubber phase while the highly vulcanized blends (DCP > 3 wt%) show co‐continuous rubber/PLA phase. In the latter blends, the tensile toughness (1.3 MJ m−3) and the tensile‐impact strength of the neat PLA (58 kJ m−2) were increased of a factor 12.5 and 8.3 respectively. Moreover, the appropriate crosslinking agent content (3–3.75 wt%) in the ternary blends allowed to reach same tensile toughness, impact strength, shape recovery and shape fixity as compared to their equivalent binary PLA/NR blends.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.