Structural Heterogeneity Dependence of the Fracture Feature Distribution in the Tensile Elongation of Microinjection Molded Polyethylene

Abstract

The microscopic structure and tensile statistical fracture behavior of microinjection molded polyethylene samples with and without a weldline were investigated as a function of mold temperature using small-angle X-ray scattering (SAXS), wide-angle X-ray diffraction (WAXD), and stress−strain measurements. Probability density functions were adopted to describe the statistical nature of bulk mechanical parameters. The distributions of the elongation at break and fracture toughness follow a Gaussian function for the samples molded at 27 and 50 °C, whereas the fracture feature distributions deviate evidently from Gaussian statistics in the case of the samples molded at 75 °C. This discrepancy is due to the different extent of structural heterogeneity along the shear flow direction as evidenced by the distributions of crystallinity and degree of molecular orientation. Being composed of a more uniform structural distribution on both the lamellar and molecular length scales across the length, a fraction of the samples molded at 75 °C can surpass the barrier of localized homogeneous deformation as observed in the ones produced at low mold temperatures upon tensile stretching and thus are globally elongated to a large strain before ultimate failure, resulting finally in a broad non-Gaussian distribution of the fracture parameters. The fracture toughness−yield stress relationships revealed that the degree of orientation of the polymeric chains is of more importance than the crystallinity with regard to the fracture toughness.

Firmware Vulnerability Detection Algorithm Based on Matching Pattern-Specific Numerical Features With Structural Features

“…Three function sets are obtained by compiling the generated binary files on three separate target platforms, namely ARM, MIPS, and x86, and are utilized as the test sets for the experiments in order to confirm the efficacy and validity of the tests. The numerical features of each function in the test set are extracted and their screening effects are compared to verify the effectiveness of MSNC [29]. For the completeness of the experimental tasks in different stages, the same experimental environment is set up, and its environmental parameters are shown in Table II.…”

Performance Enhancement of PLA-Based Blend Microneedle Arrays through Shish-Kebab Structuring Strategy in Microinjection Molding

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