Preparation Of PPTA Paper-based Composite Materials And Their Properties Study

PPTA (poly (p-phenylene terephthalamide)) paper-based composite materials are widelyused in aerospace and electrical industry because of their superior performance. Thepreparation and the properties of PPTA paper-based composite materials are discussed basedon the study of the PPTA end-group distribution, which is significant and practical. Theapproach was optimized in order to achieve PPTA MALDI-TOF spectra with highersignal-to-noise ratio and reliability. The end-group of imported and home-make PPTAshort-cut fiber and the PPTA powder produced during the beating process were characterizedwith MALDI-TOF MS. Response surface methodology (RSM) was used to investigate theprincipal influencing factor of PPTA hot pressed paper properties and the correlation amongthem. The interaction of the principal factor with the properties of PPTA hot pressed paperwas obtained. The regression model was built. The compatibility of PPTA hot pressed paperwith polyimide resin and thermal stability of polyimide resin was analyzed, aiming atdetermining the type of resin used for the PPTA hot pressed paper impregnating. Thetechnology of impregnating and curing was preliminarily discussed.The results obtained are as follows:1. The PPTA test samples for MALDI-TOF MS analysis were prepared using theevaporation-grinding (E-G) method.3-aminoquinoline was employed as matrix material withpotassium trifluoroacetate as the cationizing agent. The higher signal-to-noise ratios wereobtained at a matrix-to-polymer mixing ratio of20:1(W: W) in the reflectron mode. Theresidual traces of sulfuric acid in the samples could improve the co–crystallization betweenthe polymer and matrix. The MALDI-TOF MS spectra obtained in residual traces of sulfuricacid yield the superior signal-to-noise ratios and reliability as a result. The MALDI-TOF MScharacterization of low molecular mass oligomers of PPTA is effective.2. Structure A-1with amine-carboxyl end groups is the predominant species in thespectrum of both imported and homemade PPTA short-cut fiber. There is also trace quantitiesin imine branching structure B-7. In the polymerization of homemade PPTA fiber, there existsobvious chain transfer to solvent. So the proportions of solvent terminated structure of B-3and B-3H are higher. The species of structure in the imported PPTA powder produced duringthe beating process are fewer than that of the fibrous raw material, while the species ofstructure in the homemade PPTA powder produced during the beating process are more thanthe fibrous raw material. At the same time, the proportions of structure B-1PP, A-3P with phenyl end groups and branching structure B-7are increased in the homemade PPTA powderproduced during the beating process.3. The regression model was set up using response surface methodology, which indicatesthe effect of preparation technology of PPTA hot pressed paper on the absorbability andstrength. The quadratic formulas were obtained by optimizing the second-order polynomialmodel. The regression analysis showed that the model possessed higher regression rate,having higher coincide degree with the experimental results. This model could be used toanalyze and predict the absorbability and strength of PPTA hot pressed paper. The liner andquadratic term of hot pressing pressure, and the liner term of hot pressing temperature andproportion of PPTA short-cut fiber have highly significant effects on the Klemm absorbabilityof PPTA hot pressed paper. The liner and quadratic term of PPTA-pulp beating degree, and theliner term of hot pressing pressure and proportion of PPTA short-cut fiber have highlysignificant effects on the Gurley porosity of PPTA hot pressed paper. At the same time, theGurley porosity was significantly influenced by the interaction between the proportion ofPPTA short-cut fiber and the PPTA-pulp beating degree. Hot pressing temperature andpressure have highly significant effects on the tensile strength, tear strength and wet strengthof PPTA hot pressed paper. The proportion of PPTA short-cut fiber has highly significanteffects on the tensile strength and wet strength of PPTA hot pressed paper, and its quadraticterm has significant effect on the tear strength of PPTA hot pressed paper. The PPTA-pulpbeating degree has highly significant effect on the tear strength. At the same time, the tensilestrength was significantly influenced by the interaction between hot pressing temperature andthe proportion of PPTA short-cut fiber as well as the interaction between hot pressingtemperature and the PPTA-pulp beating degree. The interaction between hot pressingtemperature and pressure has significant effect on the wet strength of PPTA hot pressed paper.4. The polyimide resin PM1with good thermal stabilities has a good compatibility toPPTA paper-based composite materials, and the optimum concentration of PM1forimpregnating is20%. When the hot pressing temperature is220℃, the hot pressing pressureis1.5MPa by flatbed hot pressing, the tensile index of the PPTA paper-based compositematerials is91.2N·m/g. When by roll hot pressing the hot pressing temperature is180℃, thehot pressing pressure is1.5MPa, the tensile index of the PPTA paper-based compositematerials is60.4N·m/g.