酚醛树脂分子量及分布场解吸质谱表征方法研究

酚醛树脂分子量及分布的表征方法有很多,如蒸气压渗透法(VPO)、气相色谱、高压液相色谱和凝胶渗透色谱等,但由于酚醛树脂存在众多异构体,这些方法均有一定限制性.场解吸质谱(FD-MS)方法的特点是只给出样品固有组分的分子峰,不产生碎片离子峰,用于酚醛树脂的表征,可以直接得出树脂所有固有组分的分子离子峰值,及树脂不同缩合度组分的相对含量,非常适用于组份繁多的酚醛树脂的的分子量及分布表征研究.以苯酚、甲酚及甲醛等原料分别制备了Resole型苯酚-甲醛树脂、Novolac型苯酚-甲醛树脂、Novolac型甲酚树脂及混酚-甲醛树脂,利用FD-MS对制备的几种不同类型酚醛树脂的分子量及分布进行了研究.结果表明,通过FD-MS谱图分析还可以得到树脂缩聚程度、原料种类、树脂特性等信息,对于鉴别及剖析各种类型酚醛树脂方便有效.

FIELD DESORPTION MASS SPECTROMETRY CHARACTERIZATION FOR RELATIVE MOLECULAR MASS AND DISTRIBUTION OF PHENOLIC RESIN

The characterization of relative molecular mass and distribution of phenolic resins by modern analytical techniques is detailed.Common VPO,GC,HPLC and GPC methods are referenced.But these methods are restrictive in analysing the phenolic resins with more isomers.Field desorption(FD) is a term used to describe the formation of ions in the gas phase from a material deposited on a solid surface(known as an ’emitter’) in the presence of a high electrical field.The field desorption mass spectrometry(FD-MS) of the phenolic resins can give the molecular ion peak and the content of the every phenol unit without fragment ion peaks.A series of phenolic resins was made with various raw materials.The phenol-formaldehyde resole resin,the phenol-formaldehyde novolac resin,the cresol-formaldehyde novolac resin and the phenol-cresol-formaldehyde novolac resin were determined by FD-MS.The sample concentration is 10 mg/mL,the heating current is 10~30 mA/min,the ionization voltage is 5~8 kV.The FD-MS shows us the molecular ion peak and the content of the every phenol unit without any fragment ion peaks.By FD-MS analysing we can also get the informations about the degree of polymerization,raw materials,characteristics and so on.So the FD-MS method is convenient and impactful for differentiating of the various phenolic resins,suitable for the characterization of relative molecular mass and distribution of the phenolic resin.