含氢硅油改性稀土荧光竹塑复合材料的耐水性

Water resistance of rare earth fluorescent bamboo plastic composites modified with hydrogen silicone oil

为提高稀土荧光竹塑复合材料的耐水性能,拓宽其应用范围。利用含氢硅油改性竹粉和铝酸锶荧光粉表面,熔融共混,注塑成型的方法制备稀土荧光竹塑复合材料。通过接触角测量仪、荧光分光光度计、电子万能试验机、扫描电镜等仪器研究含氢硅油改性对复合材料接触角、吸水性能、发光性能和力学性能的影响。结果表明:未改性复合材料表面具有亲水性,改性复合材料表面具有疏水性。相比于未改性复合材料,改性复合材料的吸水率和吸水厚度膨胀率较低。经11 d水浸泡,改性复合材料的相对发光强度下降28.82%显著低于(P<0.05)未改性复合材料的46.40%,改性复合材料的发光性能耐水性更好。随着浸水时间的延长,复合材料的弯曲强度、弯曲模量、拉伸强度均下降并趋于稳定,冲击强度先增大后减小,然后趋于稳定,与未改性复合材料相比,改性复合材料的弯曲强度、弯曲模量、拉伸强度的下降率较低(P<0.05),改性复合材料的力学性能遇水更稳定。扫描电镜显示,改性复合材料中荧光粉和竹粉在基体中分散较均匀、团聚减少、界面黏合强度改善。复合材料经含氢硅油改性后,游离羟基数量减小,羟基吸收峰向低波数移动,在1 387.75 cm-1处出现Si-CH3的特征吸收峰,表明含氢硅油与竹纤维和荧光粉表面羟基发生了化学反应,研究结果对提高稀土荧光竹塑复合材料的耐水性具有实际意义。

To improve the water resistance of rare earth fluorescent bamboo plastic composites and broaden the scope of application, the surface of bamboo powder and strontium aluminate phosphor were modified by hydrogen-containing silicone oil. Rare earth fluorescent bamboo plastic composites modified with hydrogen-containing silicone oil were manufactured by melt blending and injection molding process. In the composites, the contents of bamboo powder and strontium aluminate phosphor were both 13.89%. The effects of hydrogen-containing silicone oil on the contact angle, water absorption, thickness swelling, emission spectrum, bending strength, bending modulus, tensile strength and impact strength of rare earth fluorescent bamboo plastic composites were investigated by using contact angle meter, fluorescence spectrophotometer, electronic universal testing machine, pendulum impact tester and so on. The tensile fracture microstructure of rare earth fluorescent bamboo plastic composites was observed by field emission scanning electron microscopy. The results from water contact angle test showed that the water contact angles of composites unmodified and modified by hydrogen-containing silicone oil were 83° and 100°, respectively, which indicated that the unmodified composite was hydrophilic and the modified composite was hydrophobic. Analysis showed that the water absorption and thickness swelling of composites increased with the increasing of soak time and then leveled off. The water absorption and thickness swelling of modified composites were smaller than those of unmodified composites. Emission spectra showed that the relative luminous intensity peak of modified composites was 67.84% higher than that of unmodified composites before being soaked in water. The relative luminous intensity of them decreased with the increasing of soak time. After being soaked in water for 11 d, the relative luminous intensity of unmodified and modified composites was decreased by 46.40% and 28.82%, respectively, indicating that the modified composites possessed better luminous stability in water. Mechanical properties showed that the mechanical properties of modified composites were superior to unmodified composites before being soaked in water. With the increasing of immersion time, the flexural strength, flexural modulus and tensile strength of composites decreased and then leveled off, and the impact strength of composites increased at first, then decreased and finally leveled off. Compared with the unmodified composites, the modified composites had better mechanical properties after being soaked in water. For modified composites, the decreasing rates of bending strength, flexural modulus and tensile strength were smaller, while the decreasing rate of the impact strength was larger. However, the impact strength of modified composites was still bigger than that of unmodified composites after being soaked in water for 11 d. Field emission scanning electron microscopy showed that in the modified composites, strontium aluminate phosphors and bamboo powder dispersed very well, the agglomeration decreased, and the interfacial adhesion strength improved. Fourier transform infrared spectroscopy results showed that after the composites were modified by hydrogen-containing silicone oil, the number of free hydroxyl groups was decreased and hydroxyl absorption peak shifted to lower wavenumber. After modification, there was a new characteristic absorption peak attributed to the Si-CH3 groups appeared in 1387.75 cm-1, which indicated that chemical reactions happened between the hydrogen-containing silicone oil and the hydroxyl of bamboo fiber and strontium aluminate phosphor surface. The research results in this paper have great practical significance on improving water resistance of rare earth fluorescent bamboo plastic composites.