Modelling and experimental investigation of microwave heating of adhesively bonded polypropylene joint

Numerical study of the thermal degradation of isotropic and anisotropic polymeric materials

“…3 and 4 correspond to cases 7, 8 and 9, i.e., orthotropic diffusion tensors. Case 7 is such that the monomer mass and energy diffusion in the x-direction, i.e., D 11 and K 11 , is ten times larger than those in the y-direction, i.e., D 22 and K 22 , while, in case 8, the thermal diffusion in the y-direction is ten times larger than that in the x-direction. These differences in the components of the diffusion tensors are clearly reflected in Fig.…”

“…Moreover, the numerical method presented here can easily handle the dependence of the thermal capacity on temperature, monomer concentration, space and time, and calculations performed with more realistic, i.e., temperature-dependent, specific heats or thermal capacities may be performed in the future. Furthermore, many studies on the curing of polymeric materials and frontal polymerization also assume that the specific heat is constant, e.g., [17][18][19][20][21][22], although mathematical models of frontal polymerization involve initiation, propagation and termination of the chain polymerization. Initiation involves two steps; in the first one, the initiator decomposes into two active radicals, while, in the second step, the radical species attach to their respective monomers to form live monomer radicals.…”

“…Figs. 9 and 10 correspond to cases 1, 2, 3, 5, 8, 13, 16 and 17 and cases 22,33,35,36,38,40,41, and 42, respectively, and show that the initial temperature profile evolves from the high temperature at the location where the heat source used to start the polymerization is placed, with very little monomer conversion and exhibits spikes at t = 400 for cases 1 and 2, whereas no spikes are observed in case 3 at this time. Spikes are not observed for t 500 in cases 1 and 2 due to the formation of a polymerization front and the no-flux conditions for heat and concentration employed in this paper.…”

“…13 and 14 illustrate the temperature and monomer concentration profiles at x = 9.9 and x = 30, respectively, along the y axis at different times for cases 22,33,35,36,38,40,41, and 42, show the nonuniformity of the temperature profiles for anisotropic polymeric composites, and indicate that cases 35 and 38 are characterized by a relative maximum in the temperature profile; the peak temperature is larger for case 35 than for case 38, whereas the other cases exhibit more uniform and lower temperature profiles at t = 400.…”

Effect of thermal expansion coefficient on the stress distribution in solar panel

“…For example, the temperature changed from À101 to 93 1C when the spacecraft in low-orbit, and the temperature changes more greatly when the spacecraft is in high-orbit. The solar panel will produce thermal stresses under the function of the space temperature field, which influence the dependability of the spacecraft and service life because of the different thermal expansion coefficients and elastic moduli resulting from the adhesion with many kinds of materials in the solar panel [3][4][5][6][7][8][9].…”