Performance of polyvinyl chloride-based E-glass reinforced isophthalic and orthophthalic polyester sandwich composites: A comparative study

This study investigates the performance of sandwich composites composed of polyvinyl chloride cores reinforced with E-glass fibers and bonded with isophthalic and orthophthalic polyester skins. The aim is to comparatively assess the mechanical and morphological characteristics of these composite structures. The comparative analysis also included variations in the skin thickness of the sandwich composite. Mechanical tests such as compressive, impact, and hardness were carried out. Moreover, fracture tests specifically focusing on single-edge notched beam fracture (mode I) were conducted under different temperature conditions, low (−10 °C), ambient (25 °C), and high (100 °C) temperatures. Comparative analysis of the mechanical properties indicated that the isophthalic-based sandwich composites exhibited superior mechanical characteristics when compared to their orthophthalic counterparts. Fracture properties of both types of sandwich composites demonstrated higher values at lower temperatures, followed by room temperature, and then high temperatures. In both types of sandwich composites, using two layers of E-glass on both sides of the polyvinyl chloride foam resulted in superior properties. This improvement can be attributed to the increased skin thickness. The interfacial properties were identified using Fourier transform infrared spectroscopy and scanning electron microscopy, revealing distinct spectroscopic features such as CH-stretching, C–O–C, CH bend, CN stretching, and NH stretching. Examination of the fractured surfaces through scanning electron microscopy revealed distinct features such as crushed fiber, fiber pull-out, honeycomb, riverline patterns, matrix-fiber delamination, and debonding, providing valuable insights into the composite's structural integrity.