The orientation of fibrillar crystals in curdlan tripropionate (CDTPr) fibers was analyzed by small angle X-ray scattering (SAXS) and transmission electron microscopy (TEM), and compared with that of poly［(R)-3-hydroxybutyrate-co-(R)-3-hydroxyvalerate］ (P(3HB-co-3HV)) fibers. Wide-angle X-ray diffraction pattern of both fibers showed fiber diagram indicating that the crystals were highly oriented along the fiber axial direction. Two clear diffraction points were observed on the meridian in SAXS pattern of P(3HB-co-3HV) fiber, which indicate lamellar crystals aligned with long period. On the other hand, no clear spot reflection was observed for CDTPr fiber and only the streak scattering was observed. TEM observation of the highly ordered structure of CDTPr fibers revealed that fibrillar crystals, 150 nm in length, were highly ordered along the fiber axis, with no clear periodicity along the fiber axis. This highly ordered structure of CDTPr seems to be the reason why no clear SAXS reflection was observed. On the other hand, in the case of P(3HB-co-3HV), lamellar crystals with a thickness of 5 nm were periodically aligned along the fiber axis, with their long axis pointing perpendicular to the fiber axis. The difference in crystal orientation can be attributed to the flexibility of the molecular chains of P(3HB-co-3HV) and CDTPr. P(3HB-co-3HV) have a folded structure in crystals, whereas those of CDTPr have an elongated chain structure in crystals.

Sharp objects like knives and axes are tools designed for cutting and chopping tasks. However, their sharp edges also make them potentially dangerous and capable of causing harm to people. Herein four distinct types of knives were examined for the penetration and damages brought on by stabbing carbon and Kevlar fabrics. The analysis stated the damage patterns resulting from the sharp impacts and concentrated on factors that influence fabric penetration. Penetration force was recorded with different knives and impact velocities on the fabric material, revealing insights into the punching behavior of carbon and Kevlar fabrics. It was observed that impacts with sharp knives at varying heights caused increased punching force and energy in both fabric materials. Notably, Kevlar fabric showed minimal depth of penetration upon impact from sharp knives. Sheep foot point knife K3 exhibited the maximum penetration force, energy, and depth of penetration due to its pointed sharp angle and substantial weight. Additionally, this knife caused less surface area breaches in the fabric. In contrast, Drop point K1, Clip point K2, and Cleaver point K4 knives resulted in larger surface damage, with average damage areas of 156mm and 95mm for carbon and Kevlar fabrics, respectively. Cleaver point knife K4 experienced the least penetration in the fabric due to its blunted structure. These findings are valuable for researchers studying knife crime offenses, knife manufacturing, and fabric types for protective body armor against stab threats. They contribute to understanding the dynamics of such attacks and informing the development of effective protective measures.