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Mechanical Properties of Polymers and Composites
14 Dec 1993-
TL;DR: In this article, the authors discuss various mechanical properties of fiber-filled composites, such as elastic moduli, creep and stress relaxation, and other mechanical properties such as stress-strain behavior and strength.
Abstract: Mechanical Tests and Polymer Transitions * Elastic Moduli * Creep and Stress Relaxation * Dynamical Mechanical Properties * Stress-Strain Behaviour and Strength * Other mechanical Properties * Particulate-Filled Polymers * Fiber- Filled Composites and Other Composites.
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TL;DR: In this article, various polypropylene/layered silicate composites were prepared with different silicate contents and the analysis of the tensile yield stress values of a large number of composites showed a broad range of variation in mechanical properties.
82 citations
TL;DR: In this paper, the authors investigated the dynamic mechanical properties of Pinus sylvestris in the radial and tangential directions of wood and found that the tangential direction had on average a higher peak temperature than the radial direction for a loss factor peak around −80°C.
Abstract: Wood is a complex cellular structure with different properties in the radial and tangential direction. Many researchers have measured dynamic properties in the longitudinal direction and a few in the radial direction but very little data can be found in the literature on dynamic mechanical properties in the tangential direction. The purpose of the work presented in this paper was to investigate the dynamic mechanical behaviour in the radial and tangential directions of wood (Pinus sylvestris). Testing was done in tension at 1 Hz with a Dynamic Mechanical Thermal Analyser. Properties in radial and tangential direction were different. The radial direction showed a higher elastic modulus and lower loss factor levels at temperatures between −120°C and 80°C. The tangential direction had on average a higher peak temperature than the radial direction for a loss factor peak around −80°C. It is the opposite of synthetic composites where the stiffer direction has a higher peak temperature. A loss factor peak at around 0°C was seen, most significantly in the tangential direction. This peak has scarcely been reported in the literature before. The distance between annual rings did not significantly affect the dynamic behaviour in the tangential direction.
82 citations
TL;DR: In this article, an experimental study was conducted to examine the influence of cyclic loading on the interfacial properties of carbon fiber/epoxy resin composites using dynamic mechanical analysis (DMA) techniques.
Abstract: An experimental study was conducted to examine the influence of cyclic loading on the interfacial properties of carbon fibre/epoxy resin composites. Two composite material systems having the same fibres and epoxy matrix, but with different fibre surface treatments, oxidised/sized and untreated, respectively, were used in this study. The existence of different interphases in these materials was studied using dynamic mechanical analysis (DMA) techniques. Fatigue tests were conducted at various load levels and then by using DMA and C-scan techniques, the fibre/matrix interfacial degradation was characterised. The results indicated that cyclic fatigue loading did affect the fibre/matrix interfacial properties of the composite laminates. Specimens with oxidised/sized fibres showed less interfacial degradation compared to laminates with untreated fibres.
81 citations
Additional excerpts
...Among other testing methods based on adsorption measurements, for example, solid gas chromatography [16], differential scanning calorimetry [17,18]; DMA has attracted increasing attention, because it provides a sensitive and non-destructive detection of the interphasial region [19, 20]....
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TL;DR: In this paper, high-filled polybenzoxazine nanocomposites with nano-SiO2 particles were investigated for their mechanical and thermal properties as a function of filler loading.
Abstract: Highly filled polybenzoxazine nanocomposites filled with nano-SiO2 particles were investigated for their mechanical and thermal properties as a function of filler loading. The nanocomposites were prepared by high shear mixing followed by compression molding. A very low A-stage viscosity of benzoxazine monomer gives it excellent processability having maximum nano-SiO2 loading as high as 30 wt% (18.8 vol%) with negligible void content. Moreover, thermal analysis of the curing process of the compound of the PBA-a/nano-SiO2 composites was found to be autocatalytic in nature with average activation energy of 79–92 kJ mol−1. Microscopic analysis (SEM) performed on the PBA-a/nano-SiO2 composite fracture surface indicated a nearly homogeneous distribution of the nano-scaled silica in the polybenzoxazine matrix. In addition, the enhancement in storage modulus of the nano-SiO2 filled polybenzoxazine composites was found to be significantly higher than that of the recently reported nano-SiO2 filled epoxy composites. The dependence of the nanocomposites’ modulus on the nano-SiO2 particles content is well fitted by the generalized Kerner equation. Furthermore, the relatively high micro-hardness of the PBA-a/nano-SiO2 composites up to about 600 MPa was achieved. Finally, the substantial enhancement in the glass transition temperature (Tg) of the PBA-a/nano-SiO2 composites was also observed with the ΔTg up to 16 °C at the nano-SiO2 loading of 30 wt%. The resulting PBA-a/nano-SiO2 composite is a highly attractive candidate as coating material in electronic packaging or other related applications.
81 citations
TL;DR: A general review of existing strain-gage technologies as applied to orthotropic-composite materials is given in this article, where specific topics addressed are gage-bonding procedures, transverse-sensitivity effects, errors due to gage misalignment, and temperature compensation methods.
Abstract: A general review of existing strain-gage technologies as applied to orthotropic-composite materials is given. The specific topics addressed are gage-bonding procedures, transverse-sensitivity effects, errors due to gage misalignment, and temperature-compensation methods. The discussion is supplemented by numerical examples where appropriate. It is shown that the orthotropic behavior of composites can result in experimental error which would not be expected based on practical experience with isotropic materials. In certain cases, the transverse sensitivity of strain gages and/or slight gage misalignment can result in strain-measurement errors exceeding 50 percent.
81 citations