Research On Self-bonding Forming Process And Mechanism Of Fiberboard

While the wood-based panel industry has developed rapidly, the problems about lack of raw materials and release of free formaldehyde also appear to be obviously. The study is carried by wood fiber as a raw material, without any adhesive and other additives, using the dry fiberboard production process, to explore the feasibility of binderless fiberboard forming and the hot-pressing process in the conditions of laboratory. And the response surface methodology is used to optimize the best process in the interaction of hot-pressing temperature, hot-pressing pressure, hot-pressing time and fiber moisture content as well. In addition, by XRD and FTIR, its forming mechanism of preliminary research is investigated. The conclusions are as follows:(1)Without any adhesive and other additives, it is possible to obtain a better performance binderless fiberboard by controlling related hot-pressing parameters.(2)The single factor tests show that in the study, hot-pressing temperature has important effect on TS and IB; with the extension of hot-pressing time, IB increases largely, MOR and MOE increase firstly, and then decrease; it is obvious for increasing fiber moisture content to reduce TS and increase IB; Density and IB have linear increase with the increase of hot-pressing pressure, while TS is linear decrease, but in the turning point of9MPa, the changes are all not large, MOR and MOE firstly increase and then reduce. When density is less than1.3g/cm3, the boards'properties improve significantly with increasing of density, but the changes are not big while greater than1.3g/cm3.(3)The response surface methodology is used to discuss the interaction of hot-pressing temperature, hot-pressing pressure, hot-pressing time and fiber moisture content, the results show that hot-pressing temperature and fiber moisture content have the remarkable interaction for MOR and MOE; there is an obvious interaction for TS and density between the interaction of hot-pressing temperature and hot-pressing pressure; the interaction of hot-pressing temperature and hot-pressing time is significant to IB.(4)According to the response surface methodology and model equation optimization, under the premise of meeting relevant requirements of the industry standard floor-based fiberboard LY/T1611-2003and the European high density fiberboard EN622-5:1997, and combining with cost of actual production, that is, the lowest hot-pressing temperature, the minimum of hot-pressing pressure, the shortest of hot-pressing time, and fiber moisture content as high as possible, finally we get the best technical parameters of binderless fiberboard under hot-pressing:hot-pressing temperature184.65℃, hot-pressing pressure5.32MPa, hot-pressing time4.02min, fiber moisture content11.54%. Considering the actual operation convenient, it can be set to:hot-pressing temperature185℃, hot-pressing pressure5MPa, hot-pressing time4min, and fiber moisture content12%.(5)The XRD and FTIR analysis show that in the study, after hot-pressing the fiber crystallinity of board is lower than the raw material, the hot-pressing conditions have made a certain degree of cellulose degradation, and its natural crystal area has been damaged. In the hot-pressing process of binderless fiberboard, a series chemical changes of fiber composition and the combination of molecular force are both helpful for the bonding process, but the main role is tend to the fact that lignin plasticizing, melting, flowing and condensing to cause the self-bonding forming.