Papers by Keyword: Modulus

Abstract: In this paper, we consider a detailed technological process for manufacturing parts, namely, a gear wheel. The proposed method with the intervention of modern 3D modelling makes it possible to improve the main indicators of quality and strength of parts. Based on the results obtained, a cycloid transcendental system of circular motion of a gear wheel with the specified basic parameters was modelled. Using multifunctional modules, we studied the vibrations of the gear wheel at different points in time. It was found that due to the fatigue and contact strength, it is possible to ensure uniform flexural strength of the gear teeth. And also, by adjusting the profile of the teeth of the part, we selected the desired strengthening coefficient. The presented dependence of the angles of inclination of the gear teeth on the transformation coefficient allows you to improve the main indicators of quality and strength by at least 2 %.

Abstract: Thermal conductivities of silicone rubber filled with Al₂O₃ were prepared. Thermal conductivity experimental results obtained were analyzed using the Nielsen and Agari models to explain the effect of Al₂O₃ filler on the formation of thermal conductive networks. Thermal conductivities increased with the adding of mixed Al₂O₃ of large and small sizes fillers. The scanning electron microscopy (SEM) showed that it is the optimum particle sizes and quantities that made the filler packing closer, which thus leads to formation of more thermal conductive chains.

Abstract: This paper presents the effect of accelerated salt spray (fog) exposure on commercially glass fiber reinforced polyester composite to determine the durability of the material. Aging behavior after exposure in the salt-spray environment was studied by mechanical properties i.e. flexural stress and flexural modulus. The accelerated salt spray exposure was conducted by Copper-Accelerated Acetic Acid Salt Spray (CASS) Test according to ASTM B368. The CASS exposure was carried out for 120 hours and observed every 24 hours. The flexural modulus results tend to be constant up to 4 days and more significant change on 5^th day of measurement. Furthermore, the morphology of specimens investigated by a Scanning Electron Microscopy (SEM). The SEM results also showed that only scratch occurred on the surface of the specimens test. The longer of the CASS exposure time, the higher the number of scratches. From this study, it could be concluded that Glass Fiber Reinforced Polyester Composite has slightly damage for 120 hours CASS test exposure.

Abstract: The composites between polyamide 11 (PA11) and functionalized graphene nanoplatelets (GNP) were prepared to compare influence of GNPs content and functionalities; hydroxyl (GO) and carboxylic acid (GC); on mechanical and thermal properties. The composites were melt compounded and injection molded into specimens with the final GNP content of 1, 3, 5, 7 and 9 wt%. It was found in XRD that these plasma-exfoliated GNPs acted as the nucleating agents that changed the crystal form of PA11, but did not have significant influence on crystallinity content. DSC analysis confirmed the nucleating effect of GNPs, which the degree of crystallinity was not affected by the presence of GNPs. The functionalities of GNP did not reduce the degradation temperature of the composites compared to neat PA11. Young's modulus and tensile strength at yield of the composites were higher with respect to the GNP content. This was attributed to stretching restriction of polymer chains by GNPs during the elastic deformation. The composites adding GO had higher tensile properties than those adding GC. In contrast, the composites adding GC showed higher impact strength than those adding GO. SEM micrographs indicated the failure of the composites occurred at the interphase between PA11 matrix and GNPs.

Abstract: Crosslinker (polyvinylsilicone oil, C gum) and curing agent (2, 5-bis (tert-butyl peroxy)-2, 5-dimethyl hexane, DBPMH) were used to change the crosslink density of the thermal conductivity of silicone rubber filled with Al₂O₃. The results show that the thermal conductivity of silicone rubber changed with its degree of crosslinking. When the Al₂O₃ loading was 5 vol. % and a completely continuous conducting network had not formed, the thermal conductivity of the vulcanizates decreased with increasing crosslink density. The thermal conductivity of the vulcanizate with a suitable amount of C gum increased to 53%, and the tensile strength increased by 0.8 MPa compared to the vulcanizate without C gum. When the Al₂O₃ loading was 30 vol. % and a completely continuous conducting network had formed, the crosslink density of vulcanizates changed as the amount of DBPMH changed. The thermal conductivity of vulcanizates first decreased and then increased with increasing crosslink density. There was a valley value in the thermal conductivity–crosslink density curve.

Abstract: The current work reports on the fabrication of composite matrix from saw dust (SD) and recycled polyethylene terephthalate (PET) at different weight ratio by flat-pressed method. Wood plastic composites (WPCs) were made with a thickness of 15 mm after mixing the saw dust and PET followed by a three phase press cycle. Physical properties (Density, Water Absorption (WA) and Thickness Swelling (TS)) and Mechanical properties (Modulus of Elasticity (MOE) and Modulus of Rupture (MOR)) were determined base on the mixing ratios according to the standard. WA and TS were measured after 2 h and 24 h of immersion in water. The results showed that as the density increased, the SD content decreased from 90 % to 50 % into the matrix. However, WA and TS decreases when the PET content increased in the matrix. Remarkably, the MOE and MOR attained a maximum point at 964.199 N/mm² and 9.03 N/mm² respectively in 50 % SD content. In comparism with standard, boards D and E can be classified as medium density boards while A, B and C are low density boards. The results indicated that the fabrication of WPCs from sawdust and PET would technically be feasible for indoor uses in building due to favorable physical properties exhibited. The mechanical properties response showed that it cannot be used for structural or load bearing application.

Abstract: This study investigated the effects of the extrusion temperature and volumetric flow rate settings in a fused filament fabrication (FFF) process on the tensile properties of specimens made of poly(ethylene-co-trimethylene terephthalate). The tensile strength almost doubled from 13.5 MPa at 230°C to 26.7 MPa at 260°C extrusion temperature, while the elongation at break improved to 5.4% and the tensile modulus rose to 641.8 MPa at the highest temperature. Similar observations were made when the extrusion flow rate was augmented to 115% of the initial value, with part strength greatly improving to 795.9 MPa and part elasticity increasing by 22%. These results illustrate two effective strategies to enhance the mechanical properties of components made in an engineering material that is increasingly being utilized in filament-based 3D printing.

Abstract: Glass fiber reinforced unsaturated polyesters were prepared by hand lay-up technique. Effect of clay conditions and loading, as well as mixing time on tensile modulus, flammability, and wear resistance were evaluated. In general, the results showed that there might be two possible structures, dispersed and agglomerated, in the composite samples. The modulus results showed that the effect of clay drying, as well as higher filler loading increase the property. In contrast, the mixing time resulted in negative effect on modulus. The improvement on modulus and flammability might be influenced by clay dispersion due to shear and viscosity change, while the decrease on modulus and wear resistance might be caused by agglomerated structures due to lubrication effect of moisture content, and less crosslink point caused by styrene evaporation.

Abstract: Fiber reinforced composite material is used widely in oil fields for its high specific strength and resistance to corrosion. Glass reinforced plastics (GRP) and Glass reinforced epoxy (GRE) pipe samples were investigated under oil field conditions. The samples were subjected to ultraviolet radiation, moisture and elevated temperature using accelerating weathering machine and then aged in different environments encountered in oil well streams and characterized by using Scanning Electron Microscopy (SEM). The surface morphology was analyzed and the images produced from wet crude and effluent water has shown different degree of deformation of the glass fiber and debonding with the polymer matrix. The tensile and modulus properties were also evaluated and effect of ageing found to be more pronounced in the case of wet crude especially for the GRE. The study revealed some tendency of GRP samples to reform the polymer matrix interface with the glass fiber after weathering. The assessment of physical properties provided information about the structural stability of composite pipes under harsh environments, which in turn can impact their overall performance and service life.

Abstract: Effects of irradiated rPP compatibilizer, on the mechanical and thermal properties of recycled polypropylene/microcrystalline cellulose composites (rPP/MCC), are investigated. rPP is irradiated with an electron beam at dosages ranging from 10, 20, 30 to 50kGy. A matrix, containing of unirradiated and irradiated rPP (50:50 by ratio), is then added to 5, 20 and 40wt% MCC fibres. The composites are prepared using a twin screw extruder, followed by injection moulding. The properties are then characterized using tensile and thermal degradation tests. The improvement of Young’s modulus by up to about 45% suggests a compatibilising effect of the irradiated rPP. Fracture surface observations reveal an adhesion between rPP matrix and MCC fibres. However, the thermal stability deteriorated with the addition of MCC and irradiated rPP.