Advanced Materials Research Vols. 652-654

Abstract: The effects of voids and the environment conditions on the curing degree and the Barcol hardness of CFRP laminates were discussed in this paper. The curing degree increased with increasing immersion time. The porosity had the negative effects on the curing degree of the specimens at the same immersion time. The Barcol hardness decreased with increasing immersion time. The porosity had no obvious effects on the Barcol hardness of the specimens at the same immersion time. The curing degree increased in the hygrothermally conditions. The effect of the environment conditions on the Barcol hardness is obvious. The Barcol hardness of the aged was lower than that of the non-aged specimens in the case of similar porosity.

Abstract: Flammability of polypropylene/vinyl acetate copolymer (PP/EVA) composites containing melamine phosphate (MP) and pentaerythritol (PER) was studied by limiting oxygen index (LOI), and UL 94. It is found that the LOI values decrease with the increase of EVA content in the PP/EVA composites. The thermal decomposition were investigated by thermogravimetric analysis. Moreover, the mechanical properties of the PP/EVA composites were studied. Compared with the flame retarded PP/EVA composites, the incorporation of a small amount of the peroxide (DCP) into the flame retarded composites leads to an increase in both tensile properties and flame retardancy.

Abstract: In this article we report the preparation of a graphene/room temperature vulcanized (RTV) silicone rubber composite. Both the morphology and the properties of the composite were investigated in detail. SEM study shows that the composite has a microphase-separated structure. PDMS is the continuous phase, and the randomly distributed graphene nanosheets and a few aggregates are the dispersed phase. However, DSC curves of the composites have only one glass transition temperature (T_g). With the increases of the graphene content, T_g increases and T_m decreases. Mechanical properties tests show that the addition of graphene has a significant reinforcement effect on silicone rubber. The tensile strength is 0.37MPa with graphene mass fraction at 1.0%, which increases 76% compared with that of pure silicone rubber parallel sample.

Abstract: The high density polyethylene (HDPE) nanocomposites were prepared by melt mixing HDPE with multi-wall carbon nanotubes (MWCNTs). In this work, the morphological, nucleation, crystallization and mechanical properties of the HDPE nanocomposites were studied by scanning electron microscopy, different scanning calorimetry, small-angle X-ray scattering and tensile testing. It was found that the tensile strength and Young’s modulus is increased by 42.4% and 116.5% at 3.wt% MWCNT loading compared to the pure HDPE. According to SEM results combined with SAXS, well-defined nanohybird shish-kebab (NHSK) entities exist in the composites, and in the shish-kebab structures fibrillous carbon nanotubes (MWCNTs) act as shish while HDPE lamellae act as kebab. The crystallization behavior, probed by DSC, suggests that MWCNTs have strong nucleation ability and shear stress plays an important role in polymer crystallization process. The mechanical properties demonstrated that the formation of the Shish-kebab structures improved the interfacial adhesion and brought obvious mechanical enhancement for the HDPE/MWCNTs nanocomposites.

Abstract: The effects of voids on the bending strength and ILSS of CFRP laminates were discussed in this paper. The bending strength and ILSS of specimens decreased with the porosity increasing from 0.33% to 1.50%. The empirical models of the bending strength and ILSS of CFRP laminates with different porosities are established by using ORIGIN software. The evolution laws of the bending strength and ILSS with different porosities were corresponding to the form of exponential function.

Abstract: The effects of voids on the tensile and compressive properties of CFRP laminates were discussed in this paper. The tensile and compressive strength of specimens decreased with the porosity increasing from 0.33% to 1.50%. The empirical models of the tensile strength and the compressive strength of CFRP laminates with different porosities are established by using ORIGIN software. The evolution laws of the tensile strength and the compressive strength with different porosities were corresponding to the form of exponential function.

Abstract: In the present study, compressive behavior of CNT reinforced Al2124 and Al6061 nanocomposites was investigated. The powders were sonicated for 30 minutes then ball milled at 200 rpm for 1 hour under argon environment. The ball milled slurry was dried and again was milled under same conditions for 15 min to disperse the agglomerated particles. The prepared powders were spark plasma sintered at 35 MPa and 450oC. Sintered specimens with final dimensions of 6 mm diameter and 12 mm length were used as standard specimens for compression tests carried out at a compression rate of 0.5 mm/min. The effect of CNT addition on the compressive modulus, percentage compression, and compressive strength was investigated.

Abstract: Composite soils have been widely used in civil engineering applications, especially in slopes, embankment dam and landfills. This paper aims to investigate effect of fiber inclusion on compaction characteristic of composite soil (i.e. clay composite). A series of laboratory tests carried out to evaluate fiber effect on optimum water content and maximum dry unit weight of composite soils. Clay was selected as soil part of the composite and natural fiber was used as reinforcement. The fiber parameters differed from one test to another, as fiber length varied from 10 mm to 20mm and fiber content were selected as 0.1% and 0.25%. For each test, compaction curved derived and the results were compared. The results proved that inclusion of fiber affected compaction behaviour of samples so that increasing in fiber content and length caused increasing in Optimum Moisture Content (OMC) and slightly decreased maximum dry unit weight.

Abstract: In this paper, Al matrix composites reinforced with Al-Ti intermetallics/Ti metal compound spherical agents were successfully fabricated through powder metallurgy way. Al-Ti intermetallic including Al₃Ti and TiAl phases are main reinforcements and inner Ti metal could not only play reinforce role but also reduce the crack sensitivity of Al-Ti intermetallics. This kind of reinforcements bonded strongly with Al matrix. As expected, the resultant composites exhibit promising mechanical properties at ambient temperature. And the mechanical property could be improved through regulating the relative thickness of the Al-Ti intermetallics and Ti metal layers.