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Thermoplastics Foams
Published in Omar Faruk , Jimi Tjong , Mohini Sain, Lightweight and Sustainable Materials for Automotive Applications, 2017
Sai Aditya Pradeep, Srishti Shukla, Nathaniel Brown, Srikanth Pilla
While polymeric foams have gained attention in the automotive industry as lightweight and less energy sensitive materials, the industry has struggled to compensate for their poor mechanical properties. Specific properties of common automotive foams are illustrated in Figure 11.5. Dependence of physical properties of foams on their relative density is well described by the Gibson and Ashby equation [21] as shown in Equation 11.3. In Equation 11.3, Pf refers to physical property of the foam, Ps is the physical property of resin/solid phase, ρf refers to foam density, ρs represents the density of parent resin, n describes another constant with a value between 1 and 2, and C describes a constant with a value of 1 for most polymer foams. It has been observed that mechanical properties of nanocellular and microcellular foams are far better than those of conventional foams, with the former having the best properties.
Foam Injection Molding
Published in S. T. Lee, Polymeric Foams, 2022
The microscopic cell size and many cells in microcellular material can not only reduce material consumption but also improve the molding thermodynamics with a quicker cycle time. The major differences between structural foam and microcellular foam are cell density and cell size. Microcellular plastic is ideally defined with a uniform cell size of about 10 μm, and a cell density as high as 109 cells/cm3 [10]. It is possible to make this kind of microstructure cell density with microcellular injection molding if material and processing are controlled very well. The maximum cell size of typical structural foam is about twice as big as the maximum cell size of the microcellular foam. The typical structural polystyrene foam has an average cell size of about 250 μm. Usually the cell density of the structural foam is about 102–106 cells/cm3. However, the cell density of the microcellular foam is 106 cells/cm3 or higher. The cell size and cell density in the foamed parts mainly determine the property differences between structural foam and microcellular foam. Microcellular foam has more advantages than structural foam because of the small cell sizes and high cell density in the foamed parts.
Analysis of selected mechanical parameters for foamed materials with non-Newtonian liquid characteristics in terms of their use in aspects of protective helmets
Published in International Journal of Occupational Safety and Ergonomics, 2020
Marcin Jachowicz, Grzegorz Owczarek
The possibility to produce foamed materials with non-Newtonian liquid characteristics has enabled their application in products for which it is very important to combine flexibility with high requirements in terms of shock-absorbing properties [4,5]. To date, materials such as rubber, plastic, elastomer materials and soft and hard microcellular polyurethane foams have been used. Textile materials capable of kinetic energy suppression [6] for certain ranges of value, with a capacity comparable to that characterizing elastomer materials, have also been in use. These materials (e.g., microporous rubber, foamed rubber, polyvinyl chloride [PVC] and nitrile mixture) used, e.g., in shockproof pads are characterized by high energy absorption capacity and a small instant flexibility (elastic return) [7,8]. To improve the protective properties, the thickness of the cushioning material can be increased. However, the greater the density and thickness of the material, and the value of the force transferred through the sample, the less suitable such material is to protect against impacts [6] because this causes a significant increase in weight and imposes restrictions of mobility.
Role of nano-SiO2 on the performance of microporous foamed polystyrene polymer
Published in Journal of Experimental Nanoscience, 2019
Anfu Guo, Hui Li, Jie Xu, Jianfeng Li, Fangyi Li
Despite the many investigations on preparation of foamed materials, the mechanism by which micromorphology affects the properties of microporous foamed materials is not fully understood. The aim of this study is to investigate the effect of nano-SiO2 on the micromorphology of microporous foamed PS materials. In this study, PS-MCF was prepared with different nano-SiO2 contents using supercritical CO2. This was aimed at understanding the effect of nano-SiO2 on the micromorphology of microporous foamed materials. The effect of nano-SiO2 on expansion ratio, cell diameter, and cell density was measured to analyze its influence on the microcellular morphology of a microcellular foamed polymer. The microstructure of PS/SiO2 was analyzed by varying the foaming temperature; further, the effect of nano-SiO2 on the optimum foaming temperature was also studied.
A review on waste wood reinforced polymer composites and their processing for construction materials
Published in International Journal of Sustainable Engineering, 2023
Katleho Keneuwe Khoaele, Oluwatoyin Joseph Gbadeyan, Viren Chunilall, Bruce Sithole
Injection moulding is used for melting granules or powder of polymeric substances inserted into a container by external heating. The molten polymer of fluidity is pressed into the mould cavity for moulding (Mohammed Alharmoodi, Hussain Idrisi, and Hamid Ismail Mourad 2022). While there is less research explicitly addressing the injection moulding process for WPCs than for extrusion processing, the topics are often related and centre on the composition and characteristics of the materials. Additionally, studies have been published on producing WPC microcellular foams using injection moulding (IM) and WPC made with biopolymers (Gardner, Han, and Wang 2015).