| Utilizing crop straws (wheat straw, rice straw) producing the non-wood based panel is one of the popular projects in field of composite study around the world. However, this kind of particleboard couldn't be widespread, especially in China, because of the high cost and characteristics of the isocyanate. In order to adapt to the needs of market, the exploitation of wheat straw particleboards made with Urea Formaldehyde(UF) or Phenol Formaldehyde(PF) has been becoming more and more concerned in China. Thus, in the aspect of modifying interface characteristics, the author of this dissertation studied the structural features, chemical components, surface wettability, acid and alkali characteristics and adhesive joints mechanism with the materials of wheat straw. As the interface of adhesive joint for wheat straw being modified by adding the coupling agent and spraying diluted alkali, the properties of UF wheat straw and PF wheat straw board were improved obviously. The PF wheat straw particle board was nearly approached to the second rank of GB/T4897-92.By using Optical Microscope (OM) and Scanning Electron Microscope (SEM), the structural features of cross section, interior and exterior surfaces for wheat straws were observed and analyzed. The results show mat the cuticle, fat and wax were the main factors of affecting adhesive joints. The phenomenon of "sputter" appeared on the exterior surface after wheat straw treated by diluted alkali.By means of Electron Spectroscopy for Chemical Analysis(ESCA), Fourier Transform Spectroscopy(FTTR), Gas Chromatography and Mass Spectrometer(GC/MS) and normal chemical analysis, surface elements and chemical components of wheat straw were analyzed. The results show that the content of C element was decrease, O and N elements were increase from exterior to interior, whereas, the content of Si was the biggest near to the exterior surface. 170 癈 was the turning point of C and O element. The contents of N and Si elements changed slightly. The results of ESCA and Micro-FTIR analysis show that reaction groups were less for exterior surface and reaction groups of interior surface were more reaction active centers than that of exterior surface. The content of moisture, ash, silicon dioxide of raw material and ash, holocellulose, lignin, pentosan, extractives of cool, hot water, Benzene and alcohol, Benzene and acetone, (ethyl) ether, 1% NaOH solution were measured. Seven fat acids in extractives of ether were identified by GC/MS. The acidity of wheat straw was found to be neutrality and its pH value was bigger than that of most of trees. The bigger buffer capacity of wheat straw was, the bigger resistance of pH was changed.By use of contact angle measuring gauge and wetting model, penetration and spreading constant K was calculated to evaluated the penetration and spreading capacity of differentadhesives on wheat straws. The bigger K value was, the stronger penetration and spreading capacity was. The experimental results showed that KMDi>KPf>KVf. After wheat straw treated by diluted alkali, the penetration and spreading capacity of three adhesives increased obviously, and equilibrium time became less. Wettability of three adhesives on the wheat straw surface was compared. The critical surface tension, the maximal work of immersion and the work of adhesion were calculated.By means of Micro-FTTR, Cross Polarization and Magic Angle Spinning 13C Nuclear Magnetic Resonance(CP/MAS 13C-NMR) and adhesive interface model, three different adhesives were mixed with cellulose separately and hot pressed. The results show that the active groups (桸H2, 桟H2OH, 桸=C=O) of UF, PF and MDI reacted with -OH group of C3, C6 in cellulose. By curve fitting of QS ESCA and comparing group contents, the results show that the surfaces of wheat straw reacted with adhesives and formed chemical absorption.According to information from FTIR, CP/MAS 13CNMR and ESCA, mechanism of adhesive joints for wheat straw was analyzed. In addition, the coupling agent's function and mechanism of function with...
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