基于互穿交联结构的PVA-硅酸钠杂化改性杨木的制备与性能

Preparation and Properties of PVA-Sodium Silicate Hybrid Modified Poplar with Interpenetrating and Cross-linking Structure

为提高无机硅酸钠浸渍改性杨木的性能,使用有机-无机杂化的方法对速生杨木进行了改性。以聚乙烯醇(PVA)为有机改性剂,硅酸钠为无机改性剂,采用分步真空-加压原位浸渍的方法制备PVA-硅酸钠杂化改性杨木。对比了杨木素材、硅酸钠改性杨木和PVA-硅酸钠杂化改性杨木的增重率、密度增大率、力学强度和阻燃抑烟性能,并采用傅里叶变换红外光谱(FT-IR)和X射线衍射仪(XRD)对化学结构和结晶结构进行了表征。结果表明,与硅酸钠浸渍改性杨木相比,PVA-硅酸钠杂化改性杨木的增重率提高了7.9%,密度增大率提高了12.3%。PVA-硅酸钠杂化改性杨木的硬度、抗弯强度、抗压强度和冲击韧性都显著提高。FT-IR分析表明,PVA和硅酸钠发生化学反应形成互穿交联结构,并与杨木中的羰基、羟基形成Si-O-C键和氢键缔合,解释了改性杨木力学性能提高的原因。XRD分析表明,PVA和硅酸钠的浸入明显降低了杨木的结晶度,这也是改性杨木冲击韧性提高的原因。PVA-硅酸钠杂化改性杨木的阻燃性能与硅酸钠浸渍改性杨木接近,但抑烟效果显著提高。PVA-硅酸钠杂化改性杨木的平均热释放速率为57.63 kW/m^(2),较杨木素材降低了28.93%;PVA-硅酸钠杂化改性杨木的总生烟量为1.255 m^(2),较杨木素材和硅酸钠浸渍改性杨木分别降低了40.3%和31.5%。

In order to improve the properties of poplar impregnated inorganic sodium silicate,the fast-growing poplar was modified by organic-inorganic hybrid method.Using polyvinyl alcohol(PVA)as organic modifier and sodium silicate as inorganic modifier,PVA-sodium silicate hybrid mo-dified poplar wood was prepared by step vacuum pressure in-situ impregnation.The weight percentage gain,density increase ratio,mechanical strength,flame retardant and smoke suppressive performance of unmodified poplar,sodium silicate modified poplar and PVA-sodium silicate hybrid modified poplar were compared.The chemical structure and crystal structure were characterized by Fourier transform infrared spectroscopy(FT-IR)and X-ray diffraction(XRD).The results showed that the weight gain rate of PVA-sodium silicate hybrid modified poplar increased by 7.9%and the density increase rate increased by 12.3%.The hardness,blending strength,compressive strength and impact toughness of poplar modified by PVA-sodium silicate hybrid were all significantly improved.FT-IR analysis showed that PVA reacted with sodium silicate to form interpenetrating cross-linking structure,and form Si-O-C bond and hydrogen bond association with carbonyl and hydroxyl in poplar,which explained the reason for the improvement of mechanical properties of modified poplar.XRD analysis shows that the immersion of PVA and sodium silicate significantly reduces the crystallinity of poplar,which is also the reason for the improvement of impact toughness of modified poplar.The flame resistance of PVA-sodium silicate hybrid modified poplar was similar to that of sodium silicate impregnated modified poplar,but the smoke suppression effect was significantly improved.The average heat release rate of poplar modified by sodium silicate was 57.63 kW/m^(2),which was 28.93%lower than that of poplar material;the total smoke production of poplar modified by PVA-sodium silicate hybrid was 1.255 m^(2),which was 40.3%and 31.5%lower than that of poplar material and sodium silicate impregnated poplar,respectively.