(85e) Characterization and Optimisation of Autoclave Production Process Parameters of Particulate Reinforced Polymer Matrix Composites for Aerospace and Marine Applications

Adeodu O. Adefemi¹, Anyaeche O. Christopher², Oluwole O. Oluleke³

^{1, 2}Department of Industrial and Production Engineering, University of Ibadan, Ibadan, Nigeria

³Department of Mechanical Engineering, University of Ibadan, Ibadan, Nigeria

Corresponding Author

adeoduac@abuad.edu.ng

ABSTRACT

Polymer matrix composites (aluminium-polyester and carbon black-polyester) are used in diverse applications due to their easy adaptability in providing tailored mechanical properties usually achieved by curing. Their production process in autoclave curing results in long processing cycle, which invariably affects the quality negatively. There is dearth of information on determining optimum process parameters for curing in autoclave oven. The objective of this study was to determine optimum process parameters for the production of aluminium-polyester and carbon black-polyester composites in autoclave oven.

Process parameters for polymer matrix composites include cure temperature, degree of cure and cure cycle according to ISO 4049 standard. Three sets of samples of polyester reinforced with aluminium and carbon black powders separately in 30.0, 20.0 and 10.0% reinforcement composition, were weighed, mixed, cast into moulds and cured in autoclave oven according to ASTM D790 standard. Temperature and degree of cure of each sample were observed inside the oven by using thermocouple and differential scanning calorimetry, respectively, at an interval of five minutes until full cure was achieved. The samples were examined for tensile properties and voids using universal testing machine and optical microscope according to ASTM D638 standard. An optimisation problem for the autoclave process was formulated for the minimisation of cure time as objective function subject to maximum and minimum allowable temperatures, as constraints. The primal problem was solved using finite difference method and optimised by genetic algorithm. The tensile strengths and micrographs of aluminium-polyester and carbon black-polyester composites from both optimised and conventional control processes were compared using t-test at α _0.05.

Autoclave oven achieved cure temperatures of 90and 75 ^oC, degree of cure of 85.0 and 80.0% in 270 and 170 minutes for aluminium-polyester and carbon black-polyester, respectively. Tensile strength of 30.0, 20.0 and 10.0% aluminium-polyester cured in autoclave had 0.0092, 0.0068 and 0.0048 MPa, respectively, while 30.0, 20.0 and 10.0% carbon black-polyester composite had 0.0032, 0.0028 and 0.0020 MPa, respectively. Micrographs of aluminium-polyester samples cured in autoclave showed mean void size of 206 μm, while micrographs of carbon black-polyester samples showed mean void size of 337 μm. Autoclave optimum process parameters were able to achieve cure temperatures of 90and 75 ^oC, degree of cure of 99.0 and 100.0% and also minimised the cure cycle to 30 and 23 minutes for aluminium-polyester and carbon black-polyester composites, respectively, compared to 230 and 170 minutes, respectively in the conventional control experiment. The 30.0, 20.0 and 10.0% optimised aluminium-polyester composites had 0.012, 0.011 and 0.0096 MPa, while 30.0, 20.0 and 10.0% optimised carbon black-polyester composites had 0.010, 0.0076 and 0.0068 MPa tensile strength, respectively. The micrographs of the optimised aluminium-polyester samples showed mean void size of 25.2 μm, while carbon black-polyester samples showed mean void size of 23.6 μm. There was an improvement in the microstructures of optimised aluminium-polyester and carbon black-polyester by 88.0 and 93.0%, respectively, compared to the conventional control samples. The variation between optimised and conventional control samples were significant for both composites.

The optimum process parameters for aluminium-polyester and carbon black-polyester composites were established. These optimum parameters are useful for curing composites with desirable microstructures and tensile strength properties

Keywords: Autoclave oven, Cure cycle, Microstructural, Co-Polymer matrix composites,

Tensile strength

Word count: 518