A microstructural approach for modelling flexural properties of long glass fibre reinforced polyamide6.6

This study focuses on the micromechanical prediction of temperature-dependent elastic properties of a composite made of a polypropylene matrix reinforced with discontinuous glass fibers. Firstly, an experimental investigation of the mechanical behavior is presented. Specimen are cut from injection-molded rectangular plates using a pattern based on fiber orientation. The microstructure is investigated by X-ray tomography at the specimen center and an average orientation tensor is calculated. Tensile tests are performed over a temperature range from ambient temperature to 85℃ and dispersion of mechanical properties is rather low; moreover, they are representative of the ones measured out of an industrial injected part. Then, the evolution of elastic properties with orientation and temperature is analyzed and compared with numerical predictions calculated with Mori–Tanaka homogenization scheme.

Section: Methodsmentioning

confidence: 99%

“…The smallest value is around 0.3 mm when a maximum of 11 mm is sometimes reached, and therefore the composite should be qualified as semi-long fiber material. 26,28…”

Section: Materials and Experimental Proceduresmentioning

confidence: 99%

Section: Materials and Experimental Procedures Materialsmentioning

confidence: 99%

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Prediction of elastic anisotropic thermo-dependent properties of discontinuous fiber-reinforced composites

Lopez

Thuillier

Grohens

2019

“…In this sense, the increase in the compatibility between the components of composites by surface treatment of filler favours the easy absorption and transfer of stress under the compressive and tensile forces, and the flexural strength is improved. 55 In the same time, the segmental motions in the neighbourhood of organic–inorganic interfaces are restricted. Figure 5(a) represents the flexural strength curves of the samples with the addition of TiO 2 at different weight percentage.…”

Section: Methodsmentioning

confidence: 99%

Nylon 612/TiO₂ composites by anionic copolymerization-molding process: Comparative evaluation of thermal and mechanical performance

Rusu¹

2019

This study describes the changes in some properties of two series of nylon 612/TiO2 composites by varying filler type (untreated and treated) and content (up 8.0 wt.%). The samples preparation by simultaneous anionic copolymerization-molding process ensures a good dispersion of the filler in matrix. Differential scanning calorimetry, thermogravimetrical analysis, static mechanical testing, dynamic mechanical analysis and scanning electron microscopy allowed to investigate the effects of filler loading on the mechanical, thermal and morphological characteristics of the samples and revealed the importance of filler treatment on the composites behaviour. The semicrystalline character has been proved by differential scanning calorimetry (only a single melting peak is present) and wide-angle X-ray diffraction (two reflexion plane with d-spacing of 0.4311 and 0.3817 nm appear). At the same filler content, the difference ΔHm1–ΔHc was higher for the samples with treated filler. The lower Tm,α(2) in comparison with Tm,α(1) revealed a modification of the nucleation process during crystallization. The main mass loss of the samples occurred between 277 and 550℃. The addition of the filler leads to the improvement of flexural strength and flexural modulus in comparison with neat copolymer. Incorporating 8.0 wt.% treated filler, the Tg value increases by about 11.0%, reaching 61.0℃.

“…Many researches have been reported on LFT usage. 3–6 Zhang et al. 7 investigated the optimal length of the fiber and fiber dispersion to achieve better mechanical properties, such as tensile and izod impact property.…”

Section: Introductionmentioning

confidence: 99%

Long fiber thermoplastic composites under high-velocity impact: Study of fiber length

Asenjan

Sabet

Nekoomanesh

2018

This study experimentally investigates the high-velocity impact response of long glass fiber-reinforced polypropylenes with different fiber lengths. The study considers three long fiber thermoplastic composites, i.e. 5, 10, and 20 mm prepared via a combination of extrusion and pultrusion processes and a crosshead die. An internal mixer was used to obtain an isotropic compound. The dispersion quality of each compound was confirmed using burn off test. A gas gun with a spherical projectile was employed to conduct high-velocity impact tests at three velocities of 144, 205, and 240 m/s. Internal mixer operation resulted in extensive fiber length reduction for all three long fiber thermoplastic lengths. Results from mechanical tests (Tensile and Izod impact) revealed an increasing value with increase in long fiber thermoplastic length, i.e. fiber length. High-velocity impact results showed higher impact performance for 20 mm long fiber thermoplastic compound compared to 5 and 10 mm long fiber thermoplastic containing specimens. Rate of increase in energy absorption from neat polypropylene to 5 and 10 mm long fiber thermoplastic compounds is much higher than from 10 to 20 mm long fiber thermoplastics. High-velocity impact tests indicated that there may be a threshold value for fiber length beyond which the fiber length plays a lesser role. Scanning electron microscopic analysis showed more fiber breakage at the impact point at a higher impact velocity than the lower end of high-velocity impact.