Void Content Measurements in Commingled E-Glass/ Polypropylene Composites Using Image Analysis from Optical Micrographs

Santulli, Carlo; Gil, R. Garcia; Long, A.C.; Clifford, M.J.

doi:10.1515/secm.2002.10.2.77

Cited by 43 publications

(25 citation statements)

References 23 publications

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“…Assuming that the intra-tape voids are not closed at these pressures and temperatures, it can be estimated that the all-PP laminates consolidated by vacuum bagging have a void content of 13% (when consolidated at 0.1 MPa pressure and 140°C) and 7% (when consolidated at 0.1 MPa and 160°C). This degree of porosity is greater than reported elsewhere for glass fibre reinforced polypropylene composites [55,56,58,59]. The thermal stability of glass fibres means that glass fibre reinforced polypropylenes can be consolidated at higher temperatures allowing greater matrix flow and so lower void content in the final parts.…”

Section: Vacuum Bagging Directly From Fabricmentioning

confidence: 63%

Direct Forming of All-Polypropylene Composites Products from Fabrics made of Co-Extruded Tapes

et al. 2009

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Many technologies presented in literature for the forming of self-reinforced or all-polymer composites are based on manufacturing processes involving thermoforming of pre-consolidated sheets. This paper describes novel direct forming routes to manufacture simple geometries of self-reinforced, all-polypropylene (all-PP) composites, by moulding fabrics of woven co-extruded polypropylene tapes directly into composite products, without the need for pre-consolidated sheet. High strength co-extruded PP tapes have potential processing advantages over mono-extruded fibres or tapes as they allow for a larger temperature processing window for consolidation. This enlarged temperature processing window makes direct forming routes feasible, without the need for an intermediate preconsolidated sheet product. Thermoforming studies show that direct forming is an interesting alternative to stamping of pre-consolidated sheets, as it eliminates an expensive belt-pressing step which is normally needed for the manufacturing of semi-finished sheets products. Moreover, results from forming studies shows that only half the energy was required to directly form a simple dome geometry from a stack of fabrics compared to stamping the same shape from a pre-consolidated sheet.

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Section: Vacuum Bagging Directly From Fabricmentioning

confidence: 63%

Direct Forming of All-Polypropylene Composites Products from Fabrics made of Co-Extruded Tapes

et al. 2009

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“…Density measurement is a common method to determine the overall void content in a sample. 32,33 Because voids have no mass but contribute to volume, the density will decrease in proportion to void content. The void content is given by ASTM D2734-09 (2009) 34 where r is the density of the void-containing specimen and r m is the density of the solid (void-free) material (reference).…”

Section: Microstructural Characterizationmentioning

confidence: 99%

Water uptake in epoxy matrix with voids: Experiments and modeling

Abdelmola

Carlsson

2018

Journal of Composite Materials

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The influence of voids on the moisture uptake of epoxy matrix has been studied. Specimens with void contents from 0 to about 50% were prepared. Void geometry and content were analyzed using microscopy and density methods. Voidcontaining samples were characterized by differential scanning calorimetry and dynamic mechanical analysis which verified consistency of chemistry. The moisture uptake of specimens immersed in distilled water at 40 C was monitored. The rate of absorption and saturation moisture content increased with increasing void content. Mass balance calculations revealed that only 6-8% of the void volume is occupied by water at saturation. The moisture uptake of void-free and void-containing specimens was non-Fickian. The Langmuir model provided better fits to the experimental results, although the high void content specimens showed substantial deviations from the Langmuir diffusion model. The moisture diffusivity of the void-free and void-containing specimens agreed reasonably with the Maxwell inclusion model.

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“…Figure shows that the voids and other features have different gray levels; consequently, an appropriate intensity threshold is widely used to automatically extract the voids. However, this simple operation cannot readily distinguish some spurious void‐like features from real voids . Figure was obtained after removing the points in Fig.…”

Section: Calculation Of Void Contentmentioning

confidence: 99%

Reduction of void content of vacuum‐assisted resin transfer molded composites by infusion pressure control

Chen

Arakawa

2014

Polymer Composites

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Vacuum-assisted resin transfer molding is a promising technique for making large and complex composite structures. However, void formation remains a problem. Two primary contributors to void formation, nonuniform resin flow and continuous evaporation of resin under low pressure, were experimentally studied. Improved pressure control at the vent is proposed to reduce the void content of the manufactured composite material: at the start of the resin infusion, the pressure at the vent is set to the full vacuum of the equipment, while after the resin has saturated all of the reinforcements, the pressure at the vent is increased slightly. The full vacuum at the start of infusion avoids air entrapment, and the slightly higher pressure later in the process restrains the resin evaporation. A lower void content is obtained. POLYM. COMPOS., 36:1629-1637

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Void Content Measurements in Commingled E-Glass/ Polypropylene Composites Using Image Analysis from Optical Micrographs

Cited by 43 publications

References 23 publications

Direct Forming of All-Polypropylene Composites Products from Fabrics made of Co-Extruded Tapes

Direct Forming of All-Polypropylene Composites Products from Fabrics made of Co-Extruded Tapes

Water uptake in epoxy matrix with voids: Experiments and modeling

Reduction of void content of vacuum‐assisted resin transfer molded composites by infusion pressure control

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