Development of critical molecular weight-property specifications for high performance polymers used as adhesives and composites

The polyimide resin, LARC-160, was prepared from diethyl-3, 3', 4,4'-benzophenone tetracarboxylate, ethyl-5-norbornene-2,3-dicarboxylate and Jeffamine AP-22. The imidization reactions of NE and BTDE were studied by HPLC, C-13-NMR and IR. NE imidizes slowly at 12 C; BTDE imidizes when the resin is heated above 100 C. Both imidization reactions proceed directly to the imide. Neither amic acid is present in significant quantities at any stage of the imidization reactions. The monomer mixture was stored at 12 C for periods up to 14 months. The effects of resin aging at this temperature on the chemical composition of the resin monomer mixture and the imidized polymer formed on curing were investigated. Aging the resin monomer mixture has the effect of partially advancing the imidization reaction. The average size of the cured polymer increases slightly with resin age

Characterization of the relationship of the cure cycle chemistry to cure cycle processing properties

Dynamic dielectric analysis (DDA) is used to study curing polymer systems and thermoplastics. Measurements are made over a frequency range of six decades. This wide range of frequencies increases the amount of information which can be obtained. The data is analyzed in terms of the frequency dependence of the complex permittivity epsilon sup *, specific conductivity sigma (ohm/cm) and the relaxation time tau, parameters which are characteristic of the cure state of the material and independent of the size of the sample

FDEMS Sensing for Automated Intelligent Processing of PMR-15

The purpose of this grant was to develop frequency dependent dielectric measurements, often called FDEMS (frequency dependent electromagnetic sensing), to monitor and intelligently control the cure process in PMR-15, a stoichiometric mixture of a nadic ester, dimethyl ester, and methylendianiline in a monomor ratio

Analytical modeling and sensor monitoring for optimal processing of advanced textile structural composites by resin transfer molding

A two-dimensional model of the resin transfer molding (RTM) process was developed which can be used to simulate the infiltration of resin into an anisotropic fibrous preform. Frequency dependent electromagnetic sensing (FDEMS) has been developed for in situ monitoring of the RTM process. Flow visualization tests were performed to obtain data which can be used to verify the sensor measurements and the model predictions. Results of the tests showed that FDEMS can accurately detect the position of the resin flow-front during mold filling, and that the model predicted flow-front patterns agreed well with the measured flow-front patterns

Microwave sensor system for continuous monitoring of adhesive curing processes

A microwave sensor system has been developed for monitoring adhesive curing processes. The system provides continuous, real-time information about the curing progress without interfering with the reaction. An open-coaxial resonator is used as the sensor head, and measurements of its resonance frequency and quality factor are performed during cure to follow the reaction progress. Additionally, the system provides other interesting parameters such as reaction rate or cure time. The adhesive dielectric properties can also be computed off-line, which gives additional information about the process. The results given by the system correlate very well with conventional measurement techniques such as differential scanning calorimetry, combining accuracy and rate with simplicity and an affordable cost. © 2012 IOP Publishing Ltd.The authors thank Rut Benavente Martinez for her assistance in the DSC experiments. The contract of BG-B is financed by the Ministry of Science and Innovation of Spain, through the 'Torres Quevedo' Sub-programme, which is also co-financed by the European Social Fund (ESF). This work has been financed by the Ministry of Science and Innovation of Spain through the project MONIDIEL (TEC2008-04109).García Baños, B.; Catalá Civera, JM.; Penaranda-Foix, FL.; Canós Marín, AJ.; Sahuquillo Navarro, O. (2012). Microwave sensor system for continuous monitoring of adhesive curing processes. Measurement Science and Technology. 23(3). https://doi.org/10.1088/0957-0233/23/3/035101S233Jost, M., & Sernek, M. (2008). Shear strength development of the phenol–formaldehyde adhesive bond during cure. Wood Science and Technology, 43(1-2), 153-166. doi:10.1007/s00226-008-0217-2Costa, M. L., Botelho, E. C., Paiva, J. M. F. de, & Rezende, M. C. (2005). Characterization of cure of carbon/epoxy prepreg used in aerospace field. Materials Research, 8(3), 317-322. doi:10.1590/s1516-14392005000300016Chen, J., & Hojjati, M. (2007). Microdielectric analysis and curing kinetics of an epoxy resin system. Polymer Engineering & Science, 47(2), 150-158. doi:10.1002/pen.20687Sernek, M., & Kamke, F. A. (2007). Application of dielectric analysis for monitoring the cure process of phenol formaldehyde adhesive. International Journal of Adhesion and Adhesives, 27(7), 562-567. doi:10.1016/j.ijadhadh.2006.10.004Núñez, L., Gómez-Barreiro, S., Gracia-Fernández, C. A., & Núñez, M. R. (2004). Use of the dielectric analysis to complement previous thermoanalytical studies on the system diglycidyl ether of bisphenol A/1,2 diamine cyclohexane. Polymer, 45(4), 1167-1175. doi:10.1016/j.polymer.2003.12.024Lefebvre, D. R., Han, J., Lipari, J. M., Long, M. A., McSwain, R. L., & Wells, H. C. (2006). Dielectric analysis for in-situ monitoring of gelatin renaturation and crosslinking. Journal of Applied Polymer Science, 101(5), 2765-2775. doi:10.1002/app.21631Cordovez, M., Li, Y., & Karbhari, V. M. (2004). Assessment of Dielectrometry for Characterization of Processing and Moisture Absorption in FRP Composites. Journal of Reinforced Plastics and Composites, 23(4), 445-456. doi:10.1177/0731684404031980Das, N. K., Voda, S. M., & Pozar, D. M. (1987). Two Methods for the Measurement of Substrate Dielectric Constant. IEEE Transactions on Microwave Theory and Techniques, 35(7), 636-642. doi:10.1109/tmtt.1987.1133722Fioretto, D., Livi, A., Rolla, P. A., Socino, G., & Verdini, L. (1994). The dynamics of poly(n-butyl acrylate) above the glass transition. Journal of Physics: Condensed Matter, 6(28), 5295-5302. doi:10.1088/0953-8984/6/28/007Givot, B. L., Krupka, J., & Belete, D. Y. (s. f.). Split post dielectric resonator technique for dielectric cure monitoring of structural adhesives. 13th International Conference on Microwaves, Radar and Wireless Communications. MIKON - 2000. Conference Proceedings (IEEE Cat. No.00EX428). doi:10.1109/mikon.2000.913931Canos, A. J., Catala-Civera, J. M., Penaranda-Foix, F. L., & Reyes-Davo, E. (2006). A novel technique for deembedding the unloaded resonance frequency from measurements of microwave cavities. IEEE Transactions on Microwave Theory and Techniques, 54(8), 3407-3416. doi:10.1109/tmtt.2006.877833Marks, R. B., & Williams, D. F. (1992). A general waveguide circuit theory. Journal of Research of the National Institute of Standards and Technology, 97(5), 533. doi:10.6028/jres.097.024Harrington, R. F. (1967). Matrix methods for field problems. Proceedings of the IEEE, 55(2), 136-149. doi:10.1109/proc.1967.5433Baker-Jarvis, J., Janezic, M. D., Domich, P. D., & Geyer, R. G. (1994). Analysis of an open-ended coaxial probe with lift-off for nondestructive testing. IEEE Transactions on Instrumentation and Measurement, 43(5), 711-718. doi:10.1109/19.328897Taylor, B. N. (1994). Guidelines for evaluating and expressing the uncertainty of NIST measurement results. doi:10.6028/nist.tn.1297Casalini, R., Corezzi, S., Livi, A., Levita, G., & Rolla, P. A. (1997). Dielectric parameters to monitor the crosslink of epoxy resins. Journal of Applied Polymer Science, 65(1), 17-25. doi:10.1002/(sici)1097-4628(19970705)65:13.0.co;2-tPreu, H., & Mengel, M. (2007). Experimental and theoretical study of a fast curing adhesive. International Journal of Adhesion and Adhesives, 27(4), 330-337. doi:10.1016/j.ijadhadh.2006.06.004Harper, D. P., Wolcott, M. P., & Rials, T. G. (2001). Evaluation of the cure kinetics of the wood/pMDI bondline. International Journal of Adhesion and Adhesives, 21(2), 137-144. doi:10.1016/s0143-7496(00)00045-2Garcia-Banos, B., Canos, A. J., Penaranda-Foix, F. L., & Catala-Civera, J. M. (2011). Noninvasive Monitoring of Polymer Curing Reactions by Dielectrometry. IEEE Sensors Journal, 11(1), 62-70. doi:10.1109/jsen.2010.2050475He, Y. (2001). 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Hybrid films of polyimide containing in situ generated silver or palladium nanoparticles: Effect of the particle precursor and of the processing conditions on the morphology and the gas permeability

International audienc

In situ generation of nanoparticulate lanthanum(III) oxide-polyimide films: characterization of nanoparticle formation and resulting polymer properties

International audienc