| The release of Volatile Organic Compounds (VOC) in furniture caused more serious indoor air pollution, and brought more attention of the country. Foreign countries have already set up systematic testing standard on home furniture pollution. Though China has issued harmful substances limit standard for some home furniture production raw materials such as artificial board, adhesive and solvent type wood coatings, its home furniture testing is only conducted by taking a part of home furniture samples as testing and experiment subjects and the testing results obtained from this are used as evaluation basis for the volatilization of volatile organic compounds of the overall home furniture.However, this method itself shows a large-randomness and poor experimental repeatability and this type of inspection method belongs to destructive inspection. Large-volume environmental test chamber method can be used to conduct overall inspection on volatile organic compounds of home furniture products. However, the temperature, humidity and air flow control items of large-volume environmental test chamber of the test equipment are under coupling constraints, the testing experiment is unable to be run stably, and the generality of the testing method is poor. For example, the test operation parameters, such as temperature, humidity, air exchange rate and load rate, can't be unified, and the different test influencing factors, such as edge banding ratio, use of reagent, position of sampling port, sampling time, sampling frequency, shelving time, are not be included in inspection standard. Therefore, it is in urgent need of a high-performance large-volume environmental test chamber system to complete corresponding test, and a perfect inspection standard for VOC of overall home furniture, so as to facilitate China to issue new inspection standard for VOC of overall home furniture as soon as possible.A series of research work has been carried out regarding the above issues aiming to provide experimental basis for the issuance of new inspection standard. The detailed research contents and innovation work are as follows:(1)Develop large-volume environmental chamber test system which is based on the volatilization testing of volatile organic compounds. The unique internal and external chamber nest and multi-channel air duct structure solve common condensation phenomenon. The system software is designed with memory and analysis functions, and equipped with hand-held sampling terminal which ensures scientific nature and reliability of sampling work. All operation parameters of this system can be adjusted in a certain range, to enable to meet all parameter requirements in current Chinese and American testing standards simultaneously, and complete nondestructive testing on all kinds of home furniture products according to different inspection standards. Research fuzzy control approach which decouples with redundant structure and simplifies control process, and adopt temperature-humidity compensation algorithm based on neural network. Solve trouble control precision brought by simultaneous action of temperature, humidity and air flow, large lag of stability, strong coupling, nonlinearity, etc.(2) In order to perfect the requirements for environmental operation parameters and experimental design parameters in inspection standard, compare the environmental operation parameters in American inspection standard ASTM E1333 with those in Chinese inspection standard GB 50325, analyze the incidence of the four parameters including temperature, relative humidity, load rate and air exchange rate on inspection results according to experimental results, and offer their optimal reference values in inspection experiment respectively, at the meantime, provide reference to realize the conversion of inspection results under different testing environmental parameters. Conduct research on the experimental design parameters not included in the requirements of Chinese and foreign inspection standards, such as edge banding ratio, use of reagent, position of sampling port, sampling time, sampling frequency, shelving time, analyze the incidence of these parameters on inspection results, and provide experimental basis for the issuance of new inspection standard.(3)On the issue of long testing period (7-28 days) of home furniture products, deduce theoretical model for release process of VOC by taking John Little model as basis, middle density fiberboard and chipboard as main research subjects and using Laplace transformation and inverse transformation. Verify the model with large-volume environmental chamber testing system which is based on the volatilization testing of VOC, and it is found that the release process matches with actual situation relatively after 5 hours. For any product of the same type, the overall release process with the period exceeding 200 hours can be calculated with its release parameters within 5 hours. Because the model calculation is rather complex and part of calculation parameters are not easy to be determined, the simplified mathematical fitting model with stronger practicability is obtained by mathematical fitting method.(4) In order to inspect and analyze the release amount of different volatile organic compounds more accurately and obtain the substance list being capable of covering volatile organic compounds volatilized from home furniture, test the samples of Batch 103 home furniture from different manufactures and regions. This article offers standard material curves of 19 different volatile gases for basis reference, thus avoiding the errors caused by taking benzene standard material curve as equivalent. Make statistics on percentages of all volatile organic compounds in all home furniture products on their TIC spectrogram by peak area normalization method, sort these organic compounds by their proportions, analyze the features of volatile matters of panel furniture, solid wood furniture and upholstered furniture to support a fact that the key testing volatile matters are different for different products.(5) In order to achieve rapid testing for volatile organic compounds and remove the boundedness of inspection subject of model calculation method, a low-cost, easily available negative pressure testing device is designed to realize the rapid testing of formaldehyde. Analyze the release process of formaldehyde gas under negative pressure condition according to the principle of pressure difference to obtain mathematic model between air pressure value and release concentration of formaldehyde gas, acquire corresponding relation between air pressure change and release amount of formaldehyde gas through experiment, and demonstrate that the rapid testing of formaldehyde can be realized by negative pressure method. |
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