Study On Wood Modification By Paraffin-oil Impregnation Technology

Paraffin-oil impregnation can develop the dimensional stability of wood and improve the mechanical properties and decay resistance. However, the relevant factor such as paraffin-oil impregnation technology, the types of petroleum wax and assortment remains have effect on the paraffin-oil impregnation, which remain to be further research. In addition, the existing traditional paraffin-oil equipment could not meet the requirements of the latest technology. In order to evaluate the influence of tree species and petroleum wax type on paraffin-oil impregnation effect, the change of dimensional stability, weight gain rate, contact angle were analysed. The relationship models between the different variables and dimensional stability were set up, a relatively new type of industrialization wax injection machine was designed and spatial heat propagation during wax injection process was explored. The main conclusions are as follows:The paraffin-oil impregnation modification technology can significantly enhance the wood dimensional stability, the influence of tree species and petroleum wax type on paraffin-oil impregnation effect was great. The influence of tree species and petroleum wax type on paraffin-oil impregnation effect had a large difference among different species. Compared to the control sample, the bulking factor of paraffin-oil with beech was decreased by 53% or more, while that of the other assortment had a decreasing amplitude ranging from 40% to 90%. There is a big difference for the distribution of petroleum wax when assortments are different. In comparison with the sample impregnated by petroleum wax, the dimensional stability of specimen impregnated by microcrystalline wax with a type of 85# would increased by more than 30% for beech with the same assortment.The wax injection time had significant effects on wax injection effect. It can significantly improve the wax injection effect by lengthening the time appropriately. Wax injection time had a peak value.There was no practical significance in improving the dimensional stability of wax injection wood to extend treat time beyond the peak value. The surface contact angle tended to be consistent after wax injection. But there was no significant correlation between the final results of the contact angle and the petroleum wax type. In addition, there is a close relationship between weight gain rate, compatibility rate and physical properties of wax. The weight gain rate of the SX105 wax injection wood was 14% higher than the other two types wax injection wood.In the wax injection process, the temperature inside the timber affect the impregnation and distribution of petroleum wax directly. The variation of temperature field is different among different positions. The thickness affects the temperature distribution, when the sample is thinner the heating rate is fasting. Ansys analysis software simulation results show that the theoretical value and the actual value is very close.The wax injection tank, heating system, condensing system are disigned theoretically in new wax injection equipment. The equipment can heat the wood uniformly. It can control the temperature flexibly and accurately. It is well sealed during the wax injection process, which can not only save the wax but also protect the environment. The dimensional stability of sample treated by the equipment is developed ideally. Compared to the control sample, the bulking rate of factor of beech treated by paraffin-oil was decreased by 56.28%, which can achieve industrialization.