Bamboo Gas Permeability Testing And Analysis

Bamboo species are widely distributed throughout the entire world. Especially China has the world's largest storage of bamboo. As a kind of green material for protecting environment, bamboo has many advantages such as fast-growing, high yield, good logging property and strong ecological functions. So its ecological, economic and social benefits will become increasingly prominent accompanied with the social development. In recent years, the research of bamboo materials has greatly developed, but there are still many areas worthy of exploiting, i.e. the relationship between bamboo physical properties, mechanical properties, chemical properties, and the processing and utilization. In this study, the researching progress of bamboo properties has be en analyzed and concluded, and the detecting system has been designed to reflect gas permeability one of the physical properties of bamboo.Leakage problem of bamboo container is one of the main factors on products'quality (bamboo wine, bamboo juice, etc.). It leads the packaging products not to be saved prolonged or metamorphosed in the long-distance transportation; so it is needed to test the permeability of bamboo, which can be helpful for choosing the bamboo materials and improve the way to deal with anti-leakage based on the tested results. Then get the best anti-seepage treatment. It usually needs to improve the permeability and increase the penetration rate in the process of bleaching or dyeing of bamboo, which helps to raise the amount of infiltration into the bamboo. Penetration rate is a physical extent reflecting the gas permeability in the bamboo material. Due to gas and liquid permeability in the bamboo are similar, its liquid permeability can be got indirectly according to the gas permeability. In this paper, bamboo gas permeability has been studied with the use of vacuum pressure method and the image analysis method. Vacuum pressure method is divided into two types:negative pressure and positive pressure. According to the structure, vacuum pressure method can be divided into two parts:vacuum pressure devices, micro-pressure electronic test and analysis. Vacuum pressure device is composed of a standard plastic anti-pressure pipe, vacuum valves, vacuum pumps, vacuum gauges, pressure gauges and air compressors, etc; the electronic test and analysis system is composed of highly sensitive piezoelectric crystal pressure sensor, data acquisition cards, signal amplifying and filtering circuit, and the air pressure signal processing software based on the LabVIEW.Image analysis method:using image processing method, it can be analyzed the pore area size changes of the stoma and the vascular bundles structure of bamboo before and after pretreatment. The penetration rate of bamboo is directly related to the porosity of bamboo material. At first, select the automatic threshold segmentation algorithm of the RGB tri-chromatic model of color image, operate automatic threshold segmentation to the R-component color image, and then eliminate the noise through opening and closing the morphological operations, at last calculate the pore area of the anatomical structures image according to standard circle area.In this study, it has respectively measured and analyzed the gas permeability on vertical, horizontal and membrane of one kind of bamboo with the use of virtual instrument detecting system on bamboo gas permeability. The result shows that bamboo structure has significant relationship with its permeability. The vertical permeability of bamboo is the strongest, while bamboo membrane has the lowest penetration rate. After the boiling pre-treatment, gas permeability of bamboo samples is significantly larger than that of those un-pretreated, which indicates that boiling pre-treatment can effectively increase the penetration rate of bamboo wood. Observing micro-porosity changes of bamboo anatomical structure before and after the boiling pretreatment through the image analysis method, the conclusion indicates that:the cross-section of the bamboo samples after boiling pretreatment, its porosity (the inner to the outer of bamboo) is larger than that of the ones without pretreatment. Therefore boiling pretreatment can increase the porosity of bamboo materials and then enhance the gas permeability of the bamboo. The application of this method can also analyze other impacts through modified approach on the internal porosity of bamboo. These conclusions can provide a theoretical basis on dealing with bamboo leak-proof staining, anti-mildew, anti-corrosion and other modification approach.