INVESTIGATION OF THE DENSITY OF A FIBROUS CELLULOSE MATRIX FOR A HEAT-INSULATING POLYMER COMPOSITE MATERIAL AT LOW PRESSING PRESSURES
For heat-insulating polymer composite materials (PCM) with a cellulose fiber filler, one of the topical issues is the change in the density of the fiber matrix under the influence of external mechanical loads. The subject of the experimental study was samples of loosened unbleached wood sulfite cellulose from coniferous wood in an air-dry state. The aim of the study is to assess the change in the bulk density of loosened pulp from the value of the pressing pressure at low pressing pressures. In experimental studies, the method of densimetry was used. Samples of loosened cellulose were obtained from the pulp folder under laboratory conditions by mechanical de-fibration. A laboratory rotary chopper was used. Loosening was carried out at a circumferential rotor speed of 50 m / s. The pressing pressure varied from 0 to 7.5 kPa. Samples of loosened cellulose with a bulk density from 11.1 to 100.0 kg/m3were obtained. The experiments were carried out in three-fold repetition. It is shown that with an increase in the pressing pressure, the bulk density of cellulose steadily increases. In the studied range of pressing pressures, the pulp compaction takes place in two stages. At the first stage, at a pressing pressure of 0 to 5 kPa, the bulk density increases from the initial value 11.1 to 87.5 kg / m3. At the second stage, when the pressing pressure exceeds 5 kPa, the bulk density increases from 87.5 to 100 kg/ m3. At the second stage, the slowdown in the increase in bulk density with an increase in the pressing pressure can be caused by the deformation of the elementary cellulose fibers. The results of the experimental study can be used to create heat-insulating PCM based on cellulose fibers.