基于剖面密度梯度（VDP）技术的意杨板材剖面密实梯度

以12 mm厚意杨Populus deltoids板材为试材，在1 MPa，100 ℃和2 ~ 5 min条件下，实施横向热压密实试验，采用剖面密度梯度（VDP）测试仪获取了密实后速生杨木锯材的断面密度分布，并利用建立的“密度-压缩率”转换公式，转换为压缩率数据，从而实现了木材断面压缩率的准连续定量和定位。结果表明：①VDP技术可以准确定量密实后木材各厚度微层的压缩率；②意杨木材断面压缩率分布与剖面密度梯度类似，呈现表高芯低的宽“V”形；在试验工艺条件下，表层约50%厚度受到不同程度的压缩，最大压缩率达到34%~37%，而芯层未受到显著压缩。图4参7

Vertical densification gradient of Populus deltoides lumber with vertical density profile (VDP) technology

Plantation wood,as a potential substitute for naturally grown wood used in flooring or furniture manufacture,is normally characterized by low-density and low-hardness,which compression can improve.To accurately locate and quantify the compression rate（CR） of Populus deltoides（poplar） lumber at each micro-layer of densified fast-growing wood,vertical density profile（VDP） technology was introduced.The 12 mm thick,fast-growing poplar lumber was compressed under 1 MPa at 100 ℃ for 2,3,and 5 min.Corresponding VDP data were transformed into CR data following a deduced mathematical equation and then graphically analyzed.Results showed that the compression rate distribution（CRD）,having a V-shaped curve,was similar to VDP with a maximum surface CR of 34%-37%.Meanwhile,the thickness in a core showed no great compression.Overall,VDP technology precisely quantified the different compression rates for different micro-layers of P.deltoides lumber.