Study On Moisture Migration Behavior Of Surface Carbonized Wood

In this study,Populus beijingensis and Pinus sylvestris were chosen as the research object.Both moisture adsorption and water absorption of two woods that carbonized at different temperature and time periods were studied by TD-NMR.The detected data were fitted by Contin software and Origin software in order to investigate the water migration of carbonization wood during moisture adsorption and water absorption,so as to obtain the optimal technical conditions of carbonization.The main conclusions are as follows:(1)The water migration of sapwood and heartwood of surface carbonized Populus beijingensis during moisture adsorption and water absorption revealed that the optimum temperature and time period for surface carbonization are 350? and 90s.At an ambient temperature of 40? and a relative humidity of 82.3%,for heartwood,the moisture adsorption balance was reached after 77.5 hours,and the moisture adsorption content is 3.5%;the water absorption balance was reached after 821h,and the water absorption content is 155.3%.For sapwood,the moisture adsorption balance was reached after 125 hours,and the moisture adsorption content is 4.9%;the water absorption balance was reached after 989 hours,and the water absorption content is 125%.(2)The water migration of heartwood and sapwood of surface carbonized Pinus sylvestris during moisture adsorption and water absorption revealed that the optimum temperature and time period for surface carbonization are 350? and 90s.At an ambient temperature of 40? and a relative humidity of 82.3%,for heartwood,the moisture adsorption balance was reached after 221 hours,and the moisture adsorption content is 4.9%;the water absorption balance was reached after 989h,and the water absorption content is 86.1%.For sapwood,the moisture adsorption balance was reached after 221 hours,and the moisture adsorption content is 5.2%;the water absorption balance was reached after 989 hours,and the water absorption content is 164.0%.(3)The T2(Spin-spin relaxation time)revealed that only bound water existed during moisture adsorption of carbonized Populus beijingensis and carbonized Pinus sylvestris.With the incensement of carbonization temperature and carbonization time,the adsorption of bound water gradually reduced,so as the signal intensity and relaxation time values of T2 distributions.But during water adsorption,the signal intensity and relaxation time values of bound water gradually reduced,the relaxation time values of free water increased,but the signal intensity decreased.(4)Comparative analyzing the water migration of carbonized Populus beijingensis and Pinus sylvestris during moisture adsorption and water absorption,the desired effect of the surface carbonized is obtained while the temperature and time period for surface carbonization were 350? and 50s.The order of moisture adsorption content from low to high:the sap wood of Populus beijingensis,the heartwood of Pinus sylvestris,the heartwood of Populus beijingensis,and the sapwood of Pinus sylvestris;the order of water absorption content from low to high:the heartwood of Pinus sylvestris,the sapwood of Populus beijingensis,the heartwood of Populus beijingensis and the sapwood of Pinus sylvestris.