In order to improve the thermal stability of condensed polynuclear aromatic(COPNA) resin synthesized from vacuum residue, 1,4-benzenedimethanol was added to cure COPNA resin. The curing mechanism was investigated by p...In order to improve the thermal stability of condensed polynuclear aromatic(COPNA) resin synthesized from vacuum residue, 1,4-benzenedimethanol was added to cure COPNA resin. The curing mechanism was investigated by proton nuclear magnetic resonance spectrometry, solid carbon-13 nuclear magnetic resonance spectrometry and Fourier transform infrared spectroscopy. Microstructures of the uncured and the cured COPNA resins were studied by scanning electron microscopy and X-ray diffractometry. The thermal stability of COPNA resins before and after curing was tested by thermogravimetric analysis. The element composition of the cured COPNA resin heated at different temperatures was analyzed by an element analyzer. The results showed that the uncured COPNA resin reacted with the cross-linking agent during the curing process, and the curing mechanism was confirmed to be the electrophilic substitution reaction. Compared with the uncured COPNA resin, the cured COPNA resin had a smooth surface, well-ordered and streamlined sheet structure with more crystalline solids, better molecular arrangement and orientation. The weight loss process of the uncured and cured COPNA resins was divided into three stages. Carbon residue of the cured COPNA resin was 41.65% at 600 ℃, which was much higher than 25.02% of the uncured COPNA resin, which indicated that the cured COPNA resin had higher thermal stability.展开更多
Novel titanium-doped silicone resins were synthesized from low-cost silane monomers and tetrabutyl titanate as raw materials and hydrochloric acid as catalyst, with titanium element as dopant into principal chain of S...Novel titanium-doped silicone resins were synthesized from low-cost silane monomers and tetrabutyl titanate as raw materials and hydrochloric acid as catalyst, with titanium element as dopant into principal chain of Si-O-Si. The resins were characterized by means of FTIR, IH NMR and 13C NMR spectra, their thermal properties and curing properties were investigated and their corresponding films were determined. The results show that the thermal stability and storage stability of the resins were influenced by the types of silane monomers containing dif- ferent carbon atomicities of organic group. The thermal stability of the titanium-doped silicone resin with a molar ratio of silane monomer B（n-propyl triethoxysilane） to silane monomer C（n-octyl triethoxysilane） being 1：1 is superior to that of the resin with a molar ratio of silane monomer B to silane monomer C being 1：3. However, the storage stability of the former is inferior to that of the latter. This work also showed that the synthesized titanium-doped silicone resins have the highest thermal stability up to 450--500℃ with an atomicity molar ratio of 1：4 of titanium to silicon in the reactants. But the best storage stability of the resin prepared from the reactants with an atomicity molar ratio of 1：6[n（Ti）：n（Si）] was obtained. The effect of the type and content of curing agent on the curing properties of the resin was also studied. Moreover, thermal mechanism and curing mechanism were proposed in this work.展开更多
麦芽糖-三聚氰胺-甲醛共缩聚(MMF)树脂是以麦芽糖、三聚氰胺和甲醛为主要原料,在碱性条件下合成而得。研究了麦芽糖与三聚氰胺的摩尔比(Mmal∶Mmel)以及固化剂对树脂热稳定性能的影响,利用DSC和FT-IR对树脂固化行为以及特征官能团的变...麦芽糖-三聚氰胺-甲醛共缩聚(MMF)树脂是以麦芽糖、三聚氰胺和甲醛为主要原料,在碱性条件下合成而得。研究了麦芽糖与三聚氰胺的摩尔比(Mmal∶Mmel)以及固化剂对树脂热稳定性能的影响,利用DSC和FT-IR对树脂固化行为以及特征官能团的变化进行了测试分析,并用Kissinger-Crane-Arrhenius方程对MMF树脂固化动力学进行了探讨。结果表明:(1)MMF树脂固化后形成了稳定的三维网络结构,游离活性基团的数量明显降低;(2)MMF树脂的热分解过程可以分为3个阶段,以氯化铵为固化剂引入MMF树脂后,体系的热稳定性能明显增强,具有更好的耐久性和热稳定性;(3)MMF树脂的固化为放热过程,相比MF树脂,MMF树脂固化放热焓值更大,固化反应更容易进行;(4)MMF树脂样品的表观活化能为72.74 k J/mol,MMF树脂固化体系的动力学模型为dα/dt=4.26×1010×e72 740/(RTp)(1-α)0.93。展开更多
基金supported by the National Natural Science Foundation of China(51172285 and 51372277)the Fundamental Research Funds for the Central Universities(14CX02060A,15CX02084A)the Natural Science Foundation of Shandong Province(ZR2011EL030)
文摘In order to improve the thermal stability of condensed polynuclear aromatic(COPNA) resin synthesized from vacuum residue, 1,4-benzenedimethanol was added to cure COPNA resin. The curing mechanism was investigated by proton nuclear magnetic resonance spectrometry, solid carbon-13 nuclear magnetic resonance spectrometry and Fourier transform infrared spectroscopy. Microstructures of the uncured and the cured COPNA resins were studied by scanning electron microscopy and X-ray diffractometry. The thermal stability of COPNA resins before and after curing was tested by thermogravimetric analysis. The element composition of the cured COPNA resin heated at different temperatures was analyzed by an element analyzer. The results showed that the uncured COPNA resin reacted with the cross-linking agent during the curing process, and the curing mechanism was confirmed to be the electrophilic substitution reaction. Compared with the uncured COPNA resin, the cured COPNA resin had a smooth surface, well-ordered and streamlined sheet structure with more crystalline solids, better molecular arrangement and orientation. The weight loss process of the uncured and cured COPNA resins was divided into three stages. Carbon residue of the cured COPNA resin was 41.65% at 600 ℃, which was much higher than 25.02% of the uncured COPNA resin, which indicated that the cured COPNA resin had higher thermal stability.
基金Supported by the Science and Technology Project of Guangdong Province, China(No.2009B011000012)
文摘Novel titanium-doped silicone resins were synthesized from low-cost silane monomers and tetrabutyl titanate as raw materials and hydrochloric acid as catalyst, with titanium element as dopant into principal chain of Si-O-Si. The resins were characterized by means of FTIR, IH NMR and 13C NMR spectra, their thermal properties and curing properties were investigated and their corresponding films were determined. The results show that the thermal stability and storage stability of the resins were influenced by the types of silane monomers containing dif- ferent carbon atomicities of organic group. The thermal stability of the titanium-doped silicone resin with a molar ratio of silane monomer B（n-propyl triethoxysilane） to silane monomer C（n-octyl triethoxysilane） being 1：1 is superior to that of the resin with a molar ratio of silane monomer B to silane monomer C being 1：3. However, the storage stability of the former is inferior to that of the latter. This work also showed that the synthesized titanium-doped silicone resins have the highest thermal stability up to 450--500℃ with an atomicity molar ratio of 1：4 of titanium to silicon in the reactants. But the best storage stability of the resin prepared from the reactants with an atomicity molar ratio of 1：6[n（Ti）：n（Si）] was obtained. The effect of the type and content of curing agent on the curing properties of the resin was also studied. Moreover, thermal mechanism and curing mechanism were proposed in this work.
文摘麦芽糖-三聚氰胺-甲醛共缩聚(MMF)树脂是以麦芽糖、三聚氰胺和甲醛为主要原料,在碱性条件下合成而得。研究了麦芽糖与三聚氰胺的摩尔比(Mmal∶Mmel)以及固化剂对树脂热稳定性能的影响,利用DSC和FT-IR对树脂固化行为以及特征官能团的变化进行了测试分析,并用Kissinger-Crane-Arrhenius方程对MMF树脂固化动力学进行了探讨。结果表明:(1)MMF树脂固化后形成了稳定的三维网络结构,游离活性基团的数量明显降低;(2)MMF树脂的热分解过程可以分为3个阶段,以氯化铵为固化剂引入MMF树脂后,体系的热稳定性能明显增强,具有更好的耐久性和热稳定性;(3)MMF树脂的固化为放热过程,相比MF树脂,MMF树脂固化放热焓值更大,固化反应更容易进行;(4)MMF树脂样品的表观活化能为72.74 k J/mol,MMF树脂固化体系的动力学模型为dα/dt=4.26×1010×e72 740/(RTp)(1-α)0.93。
