Elevated temperature mechanical behavior of nano Al₂O₃ embedded interpenetrating polymer network/glass fiber composites

Abstract

Two methods of enhancing the mechanical performance of glass fiber reinforced polymer (GFRP) composites, namely the formation of an interpenetrating polymer network (IPN) of two thermoset polymers (epoxy and vinyl ester) and the addition of nanofillers (nano Al2O3) have been implemented simultaneously. The content of nano Al2O3 (0.1, 0.4, and 0.7 wt% of the polymer matrix) in the glass fiber reinforced epoxy‐vinyl ester IPN (GEVIPN) composite significantly affected its mechanical performance. Incorporation of 0.1 wt% nano Al2O3 in GEVIPN composite exhibited 17.69% and 27.64% improvement in flexural strength and toughness, respectively. Additionally, when the composites were subjected to elevated temperature testing, their mechanical performance was drastically affected. However, the test results revealed that nano Al2O3/GEVIPN composites possessed significantly improved mechanical degradation resistance at elevated temperatures. This new composite material could be utilized as structural materials in the civil, automotive, and marine industries. Dynamic mechanical thermal analysis was performed to assess the composites' thermomechanical behavior. Fractography analysis of tested samples revealed the underlying phenomena, which dictate the mechanical performance at each testing temperature. A constitutive deformation model assessed the reliability of this new material at ambient and elevated test temperatures.

Enhanced interlaminar mechanical behavior of advanced fiber metal laminates via nano Al2O3‐IPN formation and surface pre‐treatments

“…In our previous work, it has been shown that GF composites with nano Al 2 O 3 -IPN matrix have displayed higher FS, FM and strain at peak than the GFRP composite with IPN. 30 The addition of nano Al 2 O 3 to the IPN used as the matrix phase of two FMLs in this work also revealed a similar trend. The FS of MA_0.1NA was $6% more than that of MA_N; that of CE_0.1NA was $14% more than that of CE_N.…”

“…In this work, 0.1 wt% of nano Al 2 O 3 was added to the IPN; as in our previous work, it was established that for this particular nanofiller polymer system highest dispersibility was attained at 0.1 wt%. 30 Proper dispersion of 0.1 wt% of nano Al 2 O 3 in the IPN can be seen in Figure S3. Uniform dispersion of nano Al 2 O 3 is essential for achieving high reinforcement efficiency.…”

“…16 The presence of polar groups on the chemically pre-treated aluminum surface also seems to enhance its wettability with IPN and nano Al 2 O 3 -IPN, as there is a strong possibility for the existence of chemical bonds along their interfaces. 30 Figure S8 shows the contact angles between pre-treated aluminum surfaces and IPN and nano Al ) and the ability of nano Al 2 O 3 to form hydrogen bonds due to the presence of hydroxyl groups on its surface. 26…”

“…40 Additionally, Al 2 O 3 particles, due to their nano size and high surface energy, contributed towards increasing the quality of the interfaces of IPN with aluminum and GF. 30 Both aluminum surface pre-treatment and modification of the IPN matrix by nano Al 2 O 3 enhanced the ILSS of the composites by hindering shear slippage. As a result, CE_0.1NA has shown the highest ILSS (MPa) that is $24% higher than MA_N.…”

“…The nano Al 2 O 3 particles individually dispersed within the polymer entanglements could dissipate energy through molecular relaxations and interactions. 30 Furthermore, nano Al 2 O 3 also delayed crack propagation within the matrix phase as it was functional in crack pinning, crack tip blunting, and crack bifurcation. 24 The delay in crack propagation was manifested in the form of higher strain at peak of FMLs with nano Al 2 O 3 -IPN compared to FMLs with IPN, having the same form of surface pre-treatment.…”