Study On Toughening Modification Of Phthalonitrile Resin Containing Benzoxazine Composites

Phthalonitrile resin containing benzoxazine(BA-Ph)was one of the most representative high performance nitrile resins that could autocatalytic molding at low temperature in recent years.It not only has superior physical,chemical and mechanical properties of traditional phthalonitrile resin,but also solves the problem of high curing threshold of this kind of resin over the years(long curing time,high curing temperature).BA-Ph as a resin matrix fiber reinforced composite material has begun to be used in aerospace,military industry and other fields.However,driven by high and new technology,the requirements of structural strength of composite materials in various industries are becoming higher and higher.BA-Ph still has the problem of high brittleness after it curing so that the structural strength of its composite materials is limited.According to previous studies on the toughening modification of thermosetting resin matrix,the impact strength is improved at the expense of thermal properties or bending properties.Therefore,it has become a major challenge to improve the toughness of BA-Ph while maintaining its excellent properties.So,Thesis focuses on the preparation of BA-Ph based composites with high structural strength.The specific research content is as follows:1.Firstly,the influence of different molecular weight of poly(arylene ether nitrile)containing phenolphthalein(PP-PEN)on toughening and modification BA-Ph resin matrix and BA-Ph based composites was investigated.Through the analysis of reaction kinetics theory,the toughness of BA-Ph was the best when the numerical average molecular weight(M_n)of PP-PEN was 17965 g/mol.Then the glass fiber reinforced BA-Ph based composites were prepared by hot pressing.The results showed that the toughness of the glass fiber reinforced BA-Ph based composites was improved obviously which impact strength was improved from 77 KJ/m~2 to 106 KJ/m~2 when the M_n of PP-PEN was 17965 g/mol.2.Secondly,on the basis of determining the optimal molecular weight of the toughening agent and changing the proportion of PP-PEN in BA-Ph resin matrix,the reaction and toughening mechanism of BA-Ph/PP-PEN systems as well as the optimum processing conditions,mechanical properties and other properties of fiber-reinforced composites were studied by rheological,DSC and in situ infrared characterization.The results show that when the content of the toughening agent was 20 wt.%,the influence of PP-PEN on toughening BA-Ph was best and the impact strength of fiber-reinforced composite was 149 KJ/m~2.3.Finally,vinyl MQ silicone resin was introduced into BA-Ph/PP-PEN composites,the synergistic enhancement effect between the reinforcing particles and PP-PEN was used to realize the high performance and functionalization of the composite materials,which expanded the application field of the composite materials.