Study On Synthesis Of Novel Macromolecular Coupling Agent And Its Application

Resin matrix composites, as the name implies, represent a series of compositesusing organic polymer as matrix. It has many excellent characteristics such as highspecific strength, high specific stiffness, outstanding designability, good antifatigue-fracture property and anti-corrosion ability, nice dimensional stability and easyto large scale wholly-shape, and is widely used in aerospace, automotive, electric,construction, and machinery industries. There are a great variety of inorganic particleswith diverse properties, and using inorganic ultrafine particles as reinforcing material isa commonly used method and there are a lot of applications in polymer composite field.However, due to it’s special particle size and surface properties, it’s difficult forinorganic ultrafine particles to disperse well in resin matrix besides the poor interfacebonding performance. To date, using coupling agent is one of the main ways to modifyinorganic ultrafine particles, and most of the coupling agents are small in molecularweight, the modifying effect isn’t obvious enough. Macromolecular coupling agent is anew direction in novel coupling agent developing field. But macromolecular couplingagent used in thermosetting resin matrix composites hasn’t been reported yet.This thesis aims to design and synthesize novel macromolecular coupling agentused to modify inorganic ultrafine particles, and produce thermosetting resin matrixcomposites materials of excellent comprehensive performance.In this study, three kinds of macromolecular coupling agent GBM with differentmolecular weights are designed and synthesized successfully, showing a narrowmolecular weight distribution and good thermal stability. Both GBM with differentmolecular weight and g-(2,3-epoxy-propoxy) propyl-trimethoxysilane (KH560), whichis used for comparison, are taken as the modifier to treat aluminium nitride particles(nano-AlN and micro-AlN). As a result, thermal stability of AlN particles is improvedand the particles disperse well and become more stable in organic solution. GBM ismore effective than KH560for the function of modification. Relatively, there are lessactive groups on the surface of micro-AlN than those of nano-AlN, and thermal stability of nano-AlN is improved while the changing of micro-AlN isn’t that obvious.For the nano-AlN/cyanate ester composite (nAlN/CE), effect of the addition ofnano-AlN to CE resin and its surface properties are studied. Putting nano-AlN into CEresin can decrease the cure temperature, and coupling agent modification can furtherlower it. During this case, GBM is more catalytic effect than KH560. Of all thecomposite systems, larger molecular weight contributes to higher Crosslinking Densityvalue. GBM is more beneficial for nano-AlN’s dispersion in CE matrix than KH560is.Addition of nano-AlN to CE resin can improve its thermal conductivity, coupling agentcan make the situation better, but larger molecular weight doesn’t lead to better thermalconductivity. Nano-AlN will lower the glass transition temperature (Tg) of CE resin,modification of KH560isn’t effective enough, but GBM can have a function ofmaintaining the Tg. GBM can optimize the interface of nano-AlN/CE composite, it cannot only help lower dielectric constant, but also lessen dielectric loss. The reactivefunctionality of the GBM will react with the matrix and reduce density of triazine ringto realize the toughening function besides the particles toughening effect, so GBM canimprove the impact strength of the AlN/CE system, and its toughening effect is betterthan KH560.For the micro-AlN/cyanate ester composite, effect of different coupling agent toits dielectric property is studied. Modification of coupling agent can lower the dielectricconstant differently, while the dielectric loss isn’t affected abviously. When themolecular weight is the similar, increasing anchoring chain MAH can lower thedielectric constant.