酚醛树脂作为一种热固性树脂基体具有广泛的应用。为了满足其作为高性能树脂基体在苛刻条件(耐高温和抗氧化)下的使用,进一步提高酚醛树脂的耐热性能并兼顾其工艺性能显得尤为重要。采用含有无机元素的耐热性聚合物(聚硼氮烷)和碳化硼纳米粒子协同改性酚醛树脂的方法,能够克服单独加入碳化硼导致的酚醛树脂固化温度升高的问题。固化动力学分析表明,加入聚硼氮烷的酚醛树脂改性体系,其固化转化率显著高于同温度下酚醛树脂或碳化硼改性酚醛树脂的转化率。同时,聚硼氮烷和碳化硼协同改性酚醛树脂固化物在高温阶段(800~1000℃)的热解稳定性较改性前有大幅度的提高。通过红外光谱分析了不同热解程度下酚醛树脂及其改性物的结构,进一步阐述了聚硼氮烷和碳化硼协同作用对酚醛树脂改性体系固化行为和热解过程的影响机制。上述采用耐热性活性聚合物和碳化硼陶瓷粒子协同改性热固性树脂的方法,有望在高性能复合材料树脂基体中得到运用。

Phenol-formaldehyde resin (PF) has been widely used as an excellent thermosetting resin owing to its toughness, heat tolerance, chemical inertness and good electronic property. For high performance application, especially for expanding its usage in harsh environment demanding superior thermal and oxidation stability, further enhancement of the comprehensive properties is vital. Here, a thermally stable polyborazine (PBZ) and boron carbide ceramic microparticles (B4C) were incorporated simultaneously into the phenolic resin matrix. The curing kinetics and structure evolution of the PF/B4C/PBZ composite were investigated with differential scanning calorimetry (DSC), Fourier transform IR (FTIR) and thermal gravimetric analysis (TGA). Both the curing initiation and peak temperatures of the composite were lowered as a result of the presence of active hydrogen atom of PBZ and the hydrogen bonding among PBZ and PF. In addition, the thermal stability of PF was improved in the temperature range

添加改性材料纳米蒙脱土和聚乙二醇,采用层间聚合工艺对酚醛树脂改性,以提高泡沫材料的耐热性能和韧性等;研究了酚醛配比对泡沫材料微观结构的影响;采用X射线衍射仪、红外光谱分析仪及扫描电子显微镜分析了改性酚醛树脂的结构。结果表明:聚乙二醇与酚醛树脂间发生强相互作用形成了复合物,使改性后的酚醛树脂泡沫材料韧性提高;纳米蒙脱土增加了酚醛树脂的层间距,提高了耐热性能,使热分解温度达到361℃;酚醛配比越大,树脂酸固化反应活性越低,形成的泡沫孔径越小。

Phenolic resin was modified by the addition of nano montmorillonite and polyethylene glycol via interlayer polymerization process to improve the heat resistance and toughness of the foam material. The effect of the ratio of phenol to formaldehyde on the microstructure of phenolic foam was studied. The structure of the modified phenolic resin was analyzed by X-ray diffraction (XRD), infrared spectroscopy (IR) and scanning electron microscopy (SEM). The results show that polyethylene glycol interacts with phenolic resin strongly to form the composite material, which enhances toughness of the modified phenolic resin foam material. Nano montmorillonite improves the heat resistance by increasing the distance between phenolic resin layers and consequently the thermal decomposition temperature reaches 361 ℃. The higher the ratio of phenol to formaldehyde, the lower the reactivity of acid curing reaction and the smaller the cell diameter of the foam formed.

为探究硼改性酚醛树脂与丁腈橡胶的质量比（BPF/NBR）对复合摩擦材料力学性能、耐热性能和摩擦磨损性能的影响,采用不同比例的丁腈橡胶和硼改性酚醛树脂作为复合摩擦材料基体,添加碳纤维、钢纤维、石墨、氧化铝粉和沉淀硫酸钡制成复合摩擦材料。对复合摩擦材料的密度、硬度、压缩强度和摩擦磨损性能进行了测试,用变焦距体视显微镜观察磨损表面,并分析其磨损机理。用差分扫描量热仪对摩擦材料进行耐热性分析。结果表明：BPF/NBR质量比对复合摩擦材料的力学性能、耐磨及耐热性影响较大;当硼改性酚醛树脂与丁腈橡胶质量比为6∶1时,复合摩擦材料有最高的密度、硬度和压缩强度,分别为1.933 g/cm~3、105 HRL和134 MPa;当硼改性酚醛树脂与丁腈橡胶质量比为5∶1时,摩擦材料的磨损量最小;随着BPF/NBR比例增大,复合摩擦材料表面抗犁削作用增强,黏着转移减弱。利用丁腈橡胶二次改性硼改性酚醛树脂能显著提高硼改性酚醛树脂的耐热性能,且硼改性酚醛树脂与丁腈橡胶的最佳比例介于4∶1和5∶1之间。

Phenolic resin, epoxy resin, styrene butadiene rubber and polytetrafluoroethylene can be used as friction material matrix. Due to poor wear resistance, heat resistance and adhesive properties of epoxy resin, styrene butadiene rubber and polytetrafluoroethylene, their applications in friction materials are limited. The advantages of phenolic resin on the heat resistance, adhesive property, mechanical properties, processing properties and lower cost make it become the most commonly used in adhesive base material of composite friction material. However, the pure phenolic resins are brittle, poor toughness, high hardness, poor heat resistance, low strength and large noise during using stage, so modification is an effective method to improve the comprehensive performance. The effects of different ratio of boron modified phenolic resin (BPF) and nitrile butadiene rubber (NBR) on mechanical properties, thermal stability, friction and wear properties of the friction material were investigated.

通过正交试验方法确定了SiO_2纳米粒子对酚醛树脂改性的最优条件为,反应温度80℃,反应时间180 min,反应物的配比:SiO_2纳米粒子:苯酚:甲醛为2.5:1:1.7。制备的改性酚醛树脂材料分别用热分析,傅里叶变换红外光谱和透射电镜进行表征。相比于未进行改性的酚醛树脂,SiO_2纳米粒子改性后,其热稳定性得到了明显的提升,最高可达525℃;另外在N_2的氛围中,820℃的烧蚀温度下,其固含量也增加至70%。

SiO2 nanoparticles modified phenolic resin. By orthogonal experiment method to determine the optimal conditions of SiO2 nanoparticles modified phenolic resin. Optimal experimental conditions for the reaction temperature of 80 °C, the reaction time of 180 minutes, the ratio of reactants:SiO2 nanoparticles:phenol:formaldehyde for 2.5:1:1.7. Preparation of modified phenolic resin material thermal analysis, Fourier transform infrared spectroscopy and transmission electron microscopy characterization. Not performed compared to the modified phenolic resin, the SiO2 nanoparticles modified, its thermal stability has been improved significantly, up to 525 °C;Also in N2 atmosphere, 820 °C ablative temperature. The solids content also increased to 70%.

以核桃壳经苯酚液化后的液化产物、硼酸、多聚甲醛为原料，通过固相法合成硼改性核桃壳生物基酚醛树脂（BWPF），用傅立叶红外光谱（FTIR）分析其结构，扫描电镜（SEM）观察其自然断面形貌，差示扫描量热法（DSC）与热重分析法（TG）分析其热性能。结果表明：硼酸与核桃壳液化产物中的酚羟基发生反应生成新的交联，随着硼酸加入量的增加，硼改性核桃壳生物基酚醛树脂韧性和固化温度得到提高；随着硼酸加入量的增加、反应温度的提高和反应时间的延长，硼改性核桃壳生物基酚醛树脂炭残余质量有所增加，耐热性能提高。

Boron-modified walnut shell biomass-based phenol-formaldehyde resins (BWPF)were synthesized by solid-phase generation method with the liquefied products of walnut shell in phenol,plus boric acid and paraformaldehyde as raw materials.The structure and properties of BWPF were analyzed by Fourier transform infra-red spectra (FTIR),the morphology of its natural cross section was observed by scanning electron microscope (SEM),whereas its thermal properties were analyzed by differential scanning calorimeter (DSC)and thermogravi-metric analysis (TG).The results showed that a new cross-linked bond such as B-O was formed in the process when boric acid reacted with the phenolic hydroxyl groups in the liquefied products of walnut shell.With the incre-ment of boron content,the toughness and curing temperature of BWPF were both promoted.The carbon residual mass and thermal stability of the resins were all increased with the increasing of the boric acid amount,reaction temperature and reaction time