The Cell Wall Ultrastructure And Main Chemical Composition Analysis Of Cork From Quercus Variasilis

Cork as a kind of renewable resources,its application is more and more widely,but the domestic cork from Quercus variabilis with bigger hardness and more impurity content,its physical properties are worse than cork from Quercus surber.To explain the physical and mechanical properties of domestic cork from Quercus variabilis.The virgin cork and reproduction cork of Quercus variabilis as raw materials,firstly,the structure and surface elements of cork were analyzed;secondly,the ultrastructure of cork cell wall were explored and researched;then compared and analyzed the chemical composition and characteristics of cork,and analyzed the linear correlation of composition and performance.Suberin which was the mian composition of cork,its main component was analyzed.Finally cork staining was primarily explored.Came to the following conclusions:(1)The analysis of the cork cell structure by means of scanning electron microscopy,showed that cork cell string section shape was hexagonal,a honeycomb arrangement;cross section and diameter section of cork cell shape was approximated a quadrilateral whose cell wall like brick wall arrangement.The lateral cell wall of cork cell was uneven,and there are folds.Cork cell wall was not smooth,densely covered with bumps and the cell wall had the oval material exchange channel(plasmodesmata).With scanning electron microscope and X-ray energy spectroscopy(SEM-EDAX)for elemental analysis of cork,results showed that the main elements in cork were O,C and P(H without detection),also there contained about 2.22% metal elements in cork.The content of metal elements were Na,Mg,Al,K,Ca,Fe and Cu elements,which Cu,Ca,Fe and K contents were higher,the average weight ratio respectively 0.62%,0.47% and 0.36% and 0.37%.The metal components of cork demonstrate the Quercus variabilis forest had good absorbing and conversion effect on atmospheric deposition and soil decontamination.(2)The study of cork from Quercus variabilis by means of transmission electron microscopy,found that cork structure of cell wall had three layers,which were divided into the primary wall(P),the secondary wall(S)and the third wall(T).The thickness of the secondary wall(S)was the most thick which occupies most of the cell wall.Cork cell had a lot of plasmodesmatas between the cells and its distribution was non regularity.The mature cork cell had calottes at both ends of the plasmodesmatas which blocked the plasmodesmata channels,and the cork cells became closed spaces.In cork cell wall,the compound of middle lamella(CML)and cell corner region(CCML)was more lignin distribution.(3)Through the chemical composition analysis of virgin cork and reproduction cork,the results showed that the the main chemical composition in cork were suberin,lignin,cellulose and extractives.In virgin cork,suberin content was 38.27%~39.91%;lignin content was 22.72%~24.09%;cellulose content was 10.94%~12.54%;total extractives content was 10.59%~12.33%;In reproduction cork suberin content was 39.22%~40.89%;lignin content was 19.60%~22.19%,cellulose content was 11.78%~13.85%,total extraction content was 9.76%~11.20%.Through the comparison and analysis of chemical composition and physical properties of virgin cork and reproduction cork,found that composition and performance of virgin cork and reproduction cork have certain ant difference;virgin cork cells of higher lignin content,hardness was bigger;reproduction cork cells of higher suberin content,flexibility was more excellent.The content of lignin and suberin of cork had significant effect on hardness and compression resilience.There was a significantly positive correlation between the content of lignin and wood hardness;there was a significantly negatively correlated between the content of suberin and wood hardness.15 min and 24 h compression rebound rate and suberin content showed significant positive correlation;and the content of lignin showed a significant negative correlation.(4)The analysis of suberin,indicated that most suberin monomer was C16~C24 homologue of fatty acids,and most were carbon chain alkane acid and unsaturated carbon acid.Among them,the content of saturated fatty acids was 30.18%~39.11%;unsaturated fatty acid content was 24.08%~ 37.85%.Most of them were monocarboxylic saturated fatty acids(58.92%~68.03%)and lest of them were binary carboxylic acids(3.94%~4.69%),and some of these in the middle position of the carbon chain had oxygen ring or the hydroxyl.The suberin monomers of vigin cork and reproduction were basically the same,but the monomer component content were difference.(5)The study of raw and bleached cork materials which were stained,found different dyes had significant influence on color difference and color saturation difference of this two kinds cork sheet,the thickness of cork sheet had no significant influence on the color difference and color saturation difference.Basic fuchsin,basic green and basic brown,the dyeing effect of them on bleaching materials was better than raw materials of cork.