2020. 2. 10. 15:11ㆍ카테고리 없음
Polypropylene, low-density polyethylene, and high-density polyethylene pre-production plastic pellets were weathered for three years in three experimental treatments: dry/sunlight, seawater/sunlight, and seawater/darkness. Changes in chemical bond structures (hydroxyl, carbonyl groups and carbon-oxygen) with weathering were measured via Fourier Transform Infrared (FTIR) spectroscopy.
These indices from experimentally weathered particles were compared to microplastic particles collected from oceanic surface waters in the California Current, the North Pacific Subtropical Gyre, and the transition region between the two, in order to estimate the exposure time of the oceanic plastics. Although chemical bonds exhibited some nonlinear changes with environmental exposure, they can potentially approximate the weathering time of some plastics, especially high-density polyethylene.
The majority of the North Pacific Subtropical Gyre polyethylene particles we measured have inferred exposure times 18 months, with some 30 months. Inferred particle weathering times are consistent with ocean circulation models suggesting a long residence time in the open ocean.
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Essential Ftir Software Crack
A study on the mechanism for the degraded toughness in nylon 6/clay nanocomposite is explored in this Article. Such a nanocomposite exhibits lower specific essential work of fracture w e and specific nonessential work of fracture β w p than its pure nylon 6 counterpart, as revealed by essential work of fracture (EWF) measurements.
Furthermore, the molecular orientation in a small region (20 × 20 μm 2) ahead of crack tip, obtained from micro-FTIR measurements for the first time, is found to be lower in the nanocomposite during crack initiation and propagation. The decreased molecular orientation, mostly resulted from severe microvoiding at crack tips, is responsible for the reduced specific essential work of fracture w e. Meanwhile, the molecular orientation around crack tip also indicates that lower plastic deformation occurs in the plastic zone, which is well correlated with decreased specific nonessential work of fracture β w p in the nanocomposite.