Hao Chao-wei, Zhao Ying, Li Wan-li, Xu Yi-zhuang, Wang Du-jin, Xu Duan-fu
State Key Laboratory of Polymer Physics and Chemistry, Joint Laboratory of Polymer Science and Materials, Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
Guang Pu Xue Yu Guang Pu Fen Xi. 2008 Sep;28(9):2048-52.
Temperature-dependent FT IR, DSC and POM were used to investigate the interaction between PVPK90 and nylon 6 molecules and its effect on the thermal behavior and morphology of nylon 6. DSC results suggest that the melting and crystallization behavior of nylon 6 are obviously influenced by the introduction of PVP. With the PVP content increasing, the crystallization temperature, melting temperature and the crystallinity of nylon 6 decreased, and eventually, both the exothermal and endothermic peaks could not be observed when the PVP content reached 80%, implying that the aggregation structure of nylon 6 changes from the crystalline state to the amorphous state. FTIR provided the evidence of the interaction between PVP and nylon 6 molecules. With the increase in PVP content, the peak position of nu N-H of nylon 6 gradually shifts from 3311 to 3300 cm(-1) with 90% content of PVP, and the half height peak width is broadened correspondingly. Three peaks were obtained in the carbonyl group absorption band for PVPK90/Nylon 6(50/50) and PVPK90/Nylon 6(80/20) blends from the curve-fitting results. With the addition of PVP molecules, the nu C=O of nylon 6 shifts to higher wave number and a new peak located at about 1620 cm(-1) appears and its peak area increases with the content of PVP. The above spectral variation of nu C=O and nu N-H in the PVPK90/Nylon 6 blend indicates that the carbonyl group of PVP could form H-bonding with N-H group of nylon 6 molecule, and partially destroy the hydrogen bonding between the nylon 6 molecules. POM results showed that the spherulitic size of nylon 6 decreases with the increment of the PVP and becomes more imperfect, and when the PVP content reaches 80%, no spherulites could be observed. This phenomenon is attributed to the molecular interactions between the PVP and the nylon 6 molecules, which weakens the free mobility of nylon 6 chains to form regular packing and eventually induces the change in the spherulitic morphology of nylon 6. In summary, the molecular interactions between the carbonyl group of PVP molecules and N-H group of nylon 6 molecules account for the above changes in the crystalline structure and the morphology of nylon 6 in the blends.
采用温度依赖的傅里叶变换红外光谱（FT IR）、差示扫描量热法（DSC）和偏光显微镜（POM）研究了聚乙烯吡咯烷酮K90（PVPK90）与尼龙6分子之间的相互作用及其对尼龙6热行为和形态的影响。DSC结果表明，PVP的引入对尼龙6的熔融和结晶行为有明显影响。随着PVP含量的增加，尼龙6的结晶温度、熔融温度和结晶度降低，当PVP含量达到80%时，放热峰和吸热峰均消失，这意味着尼龙6的聚集结构从结晶态转变为非晶态。FTIR为PVP与尼龙6分子之间的相互作用提供了证据。随着PVP含量的增加，尼龙6的νN-H峰位从3311 cm-1逐渐移至3300 cm-1（PVP含量为90%时），半高宽相应变宽。通过曲线拟合，在PVPK90/尼龙6（50/50）和PVPK90/尼龙6（80/20）共混物的羰基吸收带中得到三个峰。随着PVP分子的加入，尼龙6的νC=O向高波数移动，出现一个位于约1620 cm-1的新峰，且其峰面积随PVP含量增加而增大。PVPK90/尼龙6共混物中νC=O和νN-H的上述光谱变化表明，PVP的羰基可与尼龙6分子的N-H基团形成氢键，并部分破坏尼龙6分子间的氢键。POM结果表明，尼龙6的球晶尺寸随PVP含量的增加而减小且变得更不完善，当PVP含量达到80%时，未观察到球晶。这种现象归因于PVP与尼龙6分子之间的分子相互作用，该作用削弱了尼龙6链形成规则堆积的自由移动性，最终导致尼龙6球晶形态发生变化。综上所述，PVP分子的羰基与尼龙6分子的N-H基团之间的分子相互作用导致了共混物中尼龙6结晶结构和形态的上述变化。
