Abstract: The far ultraviolet rays are harmful to human health, particularly for their mutagenic effects; it can cause skin cancer, cataracts, photochemical pollution. In the future, chemists plan to use it as weapons for the destruction of objects. Therefore, we should meet this future challenge by scientific means in order to snuff out its far-ultraviolet rays. In this paper, we’ve intend to carry out a deep spectral study on a series of red dyes such as: beet red; congo red; methyl red; neutral red; phenol red and carminic acid, to find out which are able to damage far ultraviolet rays by absorption. The analysis methods used are UV-Vis absorption spectrophotometry and emission spectrophotometry. The experimental results have been carried out in our laboratory; have shown that certain red dyes have an ability to absorb light in the far ultraviolet range below 200 nm; this is due to their chemical structures. Therefore, they are able to dodging far ultraviolet rays. Moreover, the spectral analyzes by fluorescence of the series of red dyes studied, have showed that these red dyes emit beyond 600 nm.Abstract: The far ultraviolet rays are harmful to human health, particularly for their mutagenic effects; it can cause skin cancer, cataracts, photochemical pollution. In the future, chemists plan to use it as weapons for the destruction of objects. Therefore, we should meet this future challenge by scientific means in order to snuff out its far-ultraviolet ...Show More
Abstract: Food packages and kitchen utensils made of thermoplastic are very popular due to their low production costs. However, thermoplastic is easily degraded at high temperatures and has low mechanical properties. When degraded, thermoplastic produces carcinogenic monomers that can contaminate food. Thus, natural fiber-based composites are introduced. Most commercial products nowadays are made of thermosets that are difficult to degrade. In order to produce fully biodegradable composite materials, we mixed PLA (polylactic acid) pellets with bamboo. PLA is a thermoplastic polyester that is synthesized from the fermentation of plant starch. The mechanical properties of PLA/bamboo composites depend on the surface interaction between PLA and bamboo. Thus, we studied the effect of the chemical treatment of bamboo prior to composite making on the mechanical properties of PLA and bamboo. Furthermore, the morphology of bamboo was varied into powder, fiber, and strip. A four-year-old bamboo trunk was harvested and dried to minimize the moisture content. Then, it is soaked separately in cold water and 5% NaOH for 72 hours. After it is rinsed and re-dried, the fiber and powder of bamboo are extracted through mechanical treatment. The composite is made with 10% bamboo reinforcement by hot press molding technology at 220°C for 40 minutes. The tensile testing shows that only bamboo strips can improve the mechanical properties of composites. Besides, the alkali treatment was found to increase the brittleness of bamboo, causing an increase in modulus elasticity and a decrease in ductility.Abstract: Food packages and kitchen utensils made of thermoplastic are very popular due to their low production costs. However, thermoplastic is easily degraded at high temperatures and has low mechanical properties. When degraded, thermoplastic produces carcinogenic monomers that can contaminate food. Thus, natural fiber-based composites are introduced. Mos...Show More
