ABSTRACT
Concern over the effects of nanomaterials on human health has risen due to the dramatic advances in the development of various technologies based on nanomaterials. Gifu Prefecture and Gifu University are developing technologies for recycling used carbon fiber because the waste disposal process is highly cost and energy intensive. However, generation of carbon fiber dust during the recycling process is a serious issue, especially in the occupational environment. Recycling requires carbonization by partial firing treatment at 500â followed by firing treatment at 440â: these processes produce dust as a by-product. It is important to study the influence of carbon fibers on human health at a molecular level. In this study, three types of carbon fibers - before recycling, after carbonization, and after firing were evaluated for their toxic effects on mice. During the breeding period, no loss in body weight was confirmed. Further, by staining the lung tissue sections, it was found that pulmonary fibrosis did not occur. We found that these carbon fibers might not possess severe toxicity. However, we also found that the toxicity varies according to firing treatment. Furthermore, we found that firing treatment reduces the potential hazard to human health.
Subject(s)
Carbon Fiber/chemistry , Carbon/chemistry , Dust/analysis , Environmental Monitoring/methods , Recycling/methods , Animals , Body Weight/drug effects , DNA/drug effects , Environmental Pollution , Gene Expression Profiling , Hemoglobins/chemistry , Inflammation , Lung/drug effects , Male , Mice , Mice, Inbred C57BL , Occupational Exposure/adverse effects , Oligonucleotide Array Sequence Analysis , Oxidative Stress , Particle Size , RNA/analysis , Refuse DisposalABSTRACT
Temperature-sensitive gels (TSGs) are generally used in the fields of medical, robotics, MEMS, and also in daily life. In this paper, we synthesized a novel TSG with good thermal durability and a lower melting temperature below 60 °C. We discussed the physical properties of he TSG and found it provided excellent thermal expansion. Therefore, we proposed the usage of TSG to develop a strategic breathable film with controllable gas permeability. The TSG particles were prepared firstly and then blended with linear low-density polyethylene/calcium carbonate (LLDPE/CaCO3) composite to develop microporous TSG/LLDPE/CaCO3 films. We investigated the morphology, thermal, and mechanical properties of TSG/LLDPE/CaCO3 composite films. The film characterization was conducted by gas permeability testing and demonstration temperature control experiments. The uniformly porous structure and the pore size in the range of 5â»40 µm for the TSG/LLDPE/CaCO3 composite films were indicated by SEM micrographs. The demonstration temperature control experiments clearly proved the effect of the controllable gas permeability of the TSG and, more promisingly, the great practical value and application prospects of this strategic effect for the temperature-sensitive breathable film was proved.
ABSTRACT
Crystalline polymeric nanospheres composed of poly{stearyl methacrylate (SMA)-co-poly(ethylene glycol) monomethacrylate (PEGm)}s were prepared by the dispersion radical polymerization of SMA and PEGm in an ethanol/water solution. Scanning electron microscopy showed that the nanospheres were highly spherical, and had a narrow size distribution. Electron spectroscopy for chemical analysis and X-ray diffraction studies of the nanospheres suggested a core-corona-type structure; the hydrophilic PEGm corona accumulated on the nanosphere surface, while the hydrophobic SMA core formed a layered structure. Heat treatment caused a melting of the SMA layers, but successive cooling allowed it to re-form. Accompanying this reversible order-disorder transition, the nanospheres also showed a reversible aggregation/deaggregation behavior in their water-dispersion state.
ABSTRACT
Uniform polymeric nanoparticles with various morphologies of projection coronas like the viruses in the coronavirus group have been formed by the self-organization of macromolecular chains polymerizing in a dispersion system of styrene (St), acrylonitrile (AN) and poly(ethylene glycol) monomethoxymonomethacrylate (PEGm) in a polar solvent (water/ethanol). An increase in the water composition reduced the crystallization degree of AN units, resulting in a variety of the nanoparticle morphology such as the increased particle size, the reduced projection size, the increased projection number, and the decreased inter-projection distance. The difference in the projection morphology strongly affected a dispersibility in water.
