Novel composite sandwich structure from green materials: Mechanical, physical, and biological evaluation Ahmed S. O. Mohareb, 1 Ahmed H. Hassanin, 2 Alaa A. Badr, 2 Khaled T. S. Hassan, 1 Ramsis Farag 3,4 1 Forestry and Wood Technology Department, Faculty of Agriculture, Alexandria University, Egypt 2 Textile Engineering Department, Faculty of Engineering, Alexandria University, Egypt 3 Polymer and Fiber Engineering Department, Auburn University, Auburn, Alabama 36849 4 Textile Engineering Department, Faculty of Engineering, Mansoura University, Egypt Correspondence to: A. S. O. Mohareb (E - mail: ahmed_mohareb@yahoo.com) ABSTRACT: Flax and Jute fabrics were used as reinforcements with polyester resin to form composite skins while poplar particleboard was used as a core for making composite sandwich structures by applying vacuum assisted resin transfer molding (VARTM) tech- nique. Mechanical, physical, and biological properties of these novel composite sandwich structures were evaluated. The results showed that the proposed engineered panels have superior mechanical properties that are suitable for different structural applications compared with conventional particleboards. When compared with the control panels, significant enhancement on Modulus of elastic- ity (MOE) and Modulus of rupture (MOR) were achieved. On the other hand, the results indicated that the proposed panel compo- sites exhibit better dimensional stability compared with poplar particleboard control panels. In addition, the proposed composite sandwich structures proved resistant against the decay fungi after 12 weeks of fungal exposure. Obviously, the developed composite panels could be used in a wide variety of applications. V C 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42253. KEYWORDS: adhesives; biomaterials; composites; mechanical properties; polyesters Received 25 November 2014; accepted 22 March 2015 DOI: 10.1002/app.42253 INTRODUCTION The last quarter of the previous century brought a new genera- tion of composite materials that are characterized by their high strength to weight ratio, high specific stiffness, excellent fatigue resistance, and outstanding corrosion resistance compared to most common metallic alloys, such as steel and aluminum alloys. Other advantages of composites comprise their ability to entertain directional mechanical properties, low thermal expan- sion properties, and high dimensional stability. It is a combina- tion of outstanding physical, thermal, and mechanical properties that makes composites attractive to replace metals in many fields of applications, especially when weight saving is required. Composites are now used in aircrafts, helicopters, spacecrafts, satellites, ships, wind turbine blades, submarines, automotive industries, chemical processing equipment, sporting goods, and civil infrastructures. 1–3 The majority of the current commercial composites are made from synthetic polymers that are petroleum-based. Using petro- leum based composites is facing obstacles such as uncertain future of petroleum supply and price, and concerns about envi- ronmental pollution. On the other hand, agricultural derived biomass, as well as residues of wood industry are accumulating to problematic levels. It remains a major challenge to expand the sustainable and profitable use of these waste-treated residues as a raw material for value-added products which require inno- vative and environmentally friendly solutions. 4–6 Consequently, the utilization of biomass (green resource), has gained a huge attention from the researchers. 7,8 Green composites are made up from natural fibers (such as wood pulp, kenaf, hemp, Flax, Jute, henequen, pineapple leaf, sisal, etc.) and natural resins. 9–11 In the wood-based product industry, particleboard is known as a panel product manufactured from lignocellulosic materials, primarily in the form of a relatively small particles, combined with a binder and bonded together under heat and pressure. The main difference between particleboard and other wood products, such as wafer board, oriented strand board, medium density fiberboard, plywood, and hardboard, is the type of used materials and particles size. The major types of wood particles used to manufacture particleboard include wood shavings, flakes, sawdust, wafers, chips, sawdust, strands, and wood wool. 12 Table I Shows MOR and MOE values defined by EN 312 (2010) concerning boards for use in dry conditions in dif- ferent applications. 13 VARTM technique was used in this work. V C 2015 Wiley Periodicals, Inc. WWW.MATERIALSVIEWS.COM J. APPL. POLYM. SCI. 2015, DOI: 10.1002/APP.42253 42253 (1 of 8)