MC尼龙6/纳米ZnO复合材料热稳定性的原位XRD法研究

Thermal Stability of MC Nylon 6/ZnO Nanocomposite Based on Method of in situ XRD

采用原位聚合反应制备MC尼龙6/纳米ZnO复合材料．动态高温XRD(20～210℃)分析表明,随着温度的升高,MC尼龙6的α_1(200)晶面和α_2(002+202)晶面分别发生了收缩和膨胀,纯MC尼龙6和MC尼龙6/纳米ZnO复合材料的α_1和α_2晶面热膨胀系数分别为α_T^(α_1)=-8．8×10^(-5)℃^(-1),α_T^(α_2)=1．6×10^(-4)℃^(-1)和α_T^(α_1)=-1．7×10^(-4)℃^(-1),α_T^(α_2)=3．4×10^(-4)℃^(-1)．随着温度的升高,MC尼龙6/纳米ZnO复合材料相对结晶度逐渐降低,在熔融温度附近结晶结构基本被破坏,在达到升温高点后的降温过程中产生了重结晶,在20～210℃之间的结构变化基本是可逆的．加入纳米ZnO提高了MC尼龙6的热稳定性,随着纳米材料含量的增加,复合材料的热稳定性呈上升趋势,分散得越好,热稳定性越强;加入纳米ZnO使MC尼龙6的起始降解温度提高1～9℃,最大失重速率时的温度提高．

MC nylon 6/ZnO nanocomposite was prepared by in situ polymerization method. Dynamic high temperature XRD patterns indicate that with the temperature increasing the α1 （200 lattice plane） of MC nylon 6 was shnmk, but the α2 （002＋202 lattice plane） was expanded, the thermal expansion coefficients of the lattice planes of pure MC nylon 6 were αT^α1=-8.8×10-5 ℃-1 and αT^α2=1.6×10-4 ℃^-1. the thermal expansion coefficients of MC nylon 6/ZnO nanocomposites were αT^α1=-1.7×10^-4 ℃^-1 and αT^α2=3.4×10^-4 ℃^-1, respectively. With the temperature increasing, the relative crystallinity of MC nylon 6/ZnO nanocomposite decreased, the crystal structure was almost destroyed at the temperature close to the melting temperature, and with the temperature decreasing from the tiptop, it recrystallized, the variation of crystalline morphology and relative crystallinity was almost reversible in the tested temperature range from 20 to 210℃. Along with the increase of the content of nanometer particles, the thermal stability of the composites showed a rising trend. The more evenly the particles distributed, the better the thermal stability was. Nano-ZnO addition made starting degradation temperature of MC nylon 6 increased by 1-9 ℃ and the maximal weight-losing rate temperature also increased.