Preliminary Study On The Principle And Protection Of Moso Bamboo Tubes' Splitting

Bamboo is known as the second forest in our country. The area and production of bamboo in China is the highest in the world. But it easily splits during depositing and the storage, especially splitting of bamboo used out of doors is serious. Splitting causes huge waste of resources and economic loss. At present, there are few researches on bamboo tubes. How to get the better effect in the best economic ways is still in researching. This research firstly studied on systematic principle and protection of bamboo tubes'splitting, and made exact, simple and easy-operated indexes to assess splitting. In this paper,4-year old Phyllostachys pubescens bamboo used out of doors were studied. Relations of morphology parameters, basic properties and splitting were studied, to make a through inquiry into the principle and protection of bamboo tubes'splitting. The main conclusions were as follows.Assessed splitting extent of bamboo tube:When it was hard to measure crack's depth, it was suggested to use indexes:cracks'area/tube's volume (l/S), to assess splitting degree.Relation of splitting and morphology parameters of Moso bamboo:1) Tube diameter and wall thickness had significant influences on the splitting extent. When other morphology parameters were constant, bigger diameter and thicker wall were found to result in severer splitting.2) Cracks extended through tissues with low strength. Splitting get slowly at the inside.Influence of bamboo basic properties on splitting:1) Moisture content (M.C.) decreased along the height of culm with a quadratic curve, while density linearly increased along the of height. Chordwise shrinkage ratio had no significant difference on different height positons.2) On the same height positon, chordwise shrinkage ratio outside was 3 times of that inside, so splitting was easily appeared outside.3) l/S decreased with the increase of M.C. with a quadratic curve, while increased with the increase of density and chordwise shrinkage ratio with a quadratic curveDifference of properties among different wall positons:1) At non-node positon, M.C. got lower linearly and density got bigger with a quadratic curve from wall inside to outside.2) Shrinkage ratio at the outside of the wall was the biggest and it was easy to shrink. Gradients of density and shrinkage ratio were the biggest at the position near the outside and it was easy to split. Gradients of the inside wall were at the second; the smallest was in the middle of the wall.3) An the same height positon, chordwise tensile strength differed much on each radial location. It was biggest at the positon inside the wall, the value was 10.5 MPa. As the chordwise shrinkage inside was small, cracks hard expand. When near inside the wall, chordwise tensile strength sharply reduced to 5.9 MPa, and it increased up to 9.0 MPa from middle wall to outside the wall.Results of protection:Anti-crack result of getting rid of green part and brushing the body with tung oil was better than that of strapping tube body with iron hoops, and it was better to keep water in bamboo with the method.