“…According to the type of reinforcement, glass fibers, polymers, shear keys, pins and different kinds of natural fibers/fillers have been most common. A major improvement in the different mechanical properties of fiber‐reinforced PUFs has been observed by previous researchers by using different kinds of fibers . Fiber‐reinforced PUFs can be used in different industrial applications to achieve better performance in comparison to its neat counterpart.…”
Sandwich composites with a polyurethane foam (PUF) core have become a versatile set of materials with applications ranging from basic construction elements to advanced engineering materials. This diverse range of applications has provided these sandwich materials with a distinctive position in today's engineering world. This review focuses on the broad research that has been carried out on PUF core‐based sandwich composites over the years—especially in the last decade. Thorough details have been presented focusing on basic PUF core sandwich structures, advanced PUF core sandwich composites with different kinds of reinforcements and complex structures such as hybrid sandwich panels. All the research presented here has been categorized carefully, such as the types of materials used in various studies, the types of reinforcements and testing techniques used, including mechanical, electrical, dynamic, thermal and acoustic methods etc. Comparisons have also been made based on similar materials, similar testing procedures and similar application areas. Research areas have been highlighted by giving a deep insight into the most promising research, manufacturing techniques and improvement procedures. Major consumption areas and application sectors for PUF core sandwich composites have also been discussed in this review. Finally, conclusions have been made based on the results found from a literature investigation.
“…According to the type of reinforcement, glass fibers, polymers, shear keys, pins and different kinds of natural fibers/fillers have been most common. A major improvement in the different mechanical properties of fiber‐reinforced PUFs has been observed by previous researchers by using different kinds of fibers . Fiber‐reinforced PUFs can be used in different industrial applications to achieve better performance in comparison to its neat counterpart.…”
Sandwich composites with a polyurethane foam (PUF) core have become a versatile set of materials with applications ranging from basic construction elements to advanced engineering materials. This diverse range of applications has provided these sandwich materials with a distinctive position in today's engineering world. This review focuses on the broad research that has been carried out on PUF core‐based sandwich composites over the years—especially in the last decade. Thorough details have been presented focusing on basic PUF core sandwich structures, advanced PUF core sandwich composites with different kinds of reinforcements and complex structures such as hybrid sandwich panels. All the research presented here has been categorized carefully, such as the types of materials used in various studies, the types of reinforcements and testing techniques used, including mechanical, electrical, dynamic, thermal and acoustic methods etc. Comparisons have also been made based on similar materials, similar testing procedures and similar application areas. Research areas have been highlighted by giving a deep insight into the most promising research, manufacturing techniques and improvement procedures. Major consumption areas and application sectors for PUF core sandwich composites have also been discussed in this review. Finally, conclusions have been made based on the results found from a literature investigation.
“…However, when diatomite was added as a supporting material, it was observed that the PUF biocomposites had a rougher surface and pore diameters smaller than PUF. The reduced cell size may be owing to the silica acting as a nucleating agent, and the deformation of the cell walls is increased with increasing filler concentrations 45 , 46 . Figure 2 SEM images of the PUF reinforced with ( a ) 0% diatomite; ( b ) 1% diatomite; ( c ) 2% diatomite and ( d ) 5% diatomite.…”
Porous three-dimensional (3D) polyurethane-based biocomposites were produced utilizing diatomite and hydroxyapatite as fillers. Diatomite and Hydroxyapatite (HA) were utilized to reinforce the morphological, chemical, mechanical, and thermal properties of polyurethane foam (PUF). Diatomite and Hydroxyapatite were added into polyurethane at variable percentages 0, 1, 2, and 5. The mechanical properties of PUF were analyzed by the compression test. According to the compression test results, the compressive strength of the polyurethane foam is highest in the reinforced foam at 1% by weight hydroxyapatite compared to other reinforced PUFs. Scanning electron microscopy (SEM) images presented structural differences on foam by adding fillers. Functional groups of PUF were defined by Fourier Transform Infrared Spectroscopy (FTIR) and the thermal behavior of PUF was studied with Thermogravimetric Analysis (TGA). The obtained results revealed that PUF/HA biocomposites indicated higher thermal degradation than PUF/Diatomite biocomposites. The bone can be regarded as a composite substance composed of inorganic minerals mostly formed through hydroxyapatite (HA), which reinforces the bone structure and supplies mechanical strength and moreover an organic matrix consisting of type I collagen. Bone is good at self-regeneration, but the natural healing mechanism is difficult when significant bone loss, so medical implants are generally utilized to overcome the defect of bone. The temporary 3D scaffold, according to the bone tissue engineering approach, plays a significant role in controlling osteoblast functions as well as a fundamental role in guiding the new formation of bone into preferred forms 1. Scaffolds for bone regeneration serve primarily as substrates for binding and proliferation of osteogenic cells. Thus, like bone grafts, three-dimensional biodegradable materials with a porous structure were of big interest not only for their structural and composition similarities to the natural bone but also for their original functional properties, like greater surface area, and high mechanical strength 2. The most studied synthetic biodegradable polymers studied for bone tissue engineering include polylactic acid (PLA), polycaprolactones (PCL), polyglycolide (PGA), and polylactic-co-glycolic acid (PLGA) 3,4. However, when artificial biodegradable polymers are used, the right equilibrium among the rate of tissue regeneration and in vivo degradation is hard to accomplish. For this reason, other polymers, especially polyurethanes, can be utilized to produce scaffolds for the regeneration of bone tissue. The use of polyurethane for scaffolding is probable to achieve a much wider range of morphological and mechanical characteristics compared to mostly used biodegradable polymers 5. Polyurethanes (PU) are classically produced by polyaddition reactions of isocyanates with polyols (polyalcohols). Based on the formulation, a wide property spectrum from elastomer to rigid foams are readily designed and synthesized 6-8. Currently, they are...
“…STF contains SiO 2 that reacts with PEG to form particulate matter and strengthen the mechanical properties of the composites. However, excessive STF fails to be dispersed evenly and causes agglomeration and uneven cell size, which adversely affect the cell morphology and the bending property of the composites . Figure (d) shows the bending property curve of pure rigid PU foam without STF and composites made with 1 wt % STF containing 14, 40, and 75 nm SiO 2 .…”
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