Some wetting and adhesion phenomena in polypropylene composites

Elmendorp, J. J.; Schoolenberg, G.E.

doi:10.1007/978-94-011-0523-1_6

Cited by 8 publications

(9 citation statements)

References 16 publications

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“…Equation (2) was shown to correlate well with experimental observations of polypropylene wetting a glass surface [14]. This indicates that the local wetting inside fiber bundles, in particular at a low global pressure, will be positively affected by a low polymer viscosity and a strong physical interaction between the liquid and the fiber surface.…”

Section: Capillary Phenomena and Micro-impregnationsupporting

confidence: 68%

“…Its behavior was Newtonian at shear rates below 10 s 1 ; as the shear rate in the matrix during impregnation was estimated to be approximately 1 s −1 , the matrix behavior can thus be considered Newtonian. The value of the surface tension for the polypropylene is given as γ lv = 0.0208 N/m, and the static contact angle on glass is taken as θ = 0 [14]. A model matrix consisting of polyethylene glycol (PEG) mixed with water was used to perform experiments at room temperature.…”

Section: Matrix Materialsmentioning

confidence: 99%

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Impregnation of Compressible Fiber Mats with a Thermoplastic Resin. Part II: Experiments

Michaud¹,

Törnqvist²,

Månson

2001

Journal of Composite Materials

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The impregnation of compressible glass fiber mats by a thermoplastic resin in the transverse direction is investigated with application to the Glass Mat reinforced Thermoplastics (GMT) lamination process in a double belt press. A model proposed in Part I to simulate the kinetics of impregnation and the evolution of the fiber volume fraction profile as the resin front progresses across the fiber mat, as well as after macro-impregnation is complete, is further developed to include micro-impregnation effects. The predictions are compared with experimental results obtained using model systems such as polyethylene glycol and glass fiber mats, as well as an industrially relevant system consisting of polypropylene and glass fiber mats used in the production of GMT blanks. It is shown that significant compression of the fiber mat may occur during impregnation, with subsequent relaxation on a much longer time-scale. Also, fiber bundle impregnation generally occurs after macro-impregnation is complete, the driving force being the local pressure in the resin around the bundles, dictated by the local state of compression of the mat. The model is then used to provide guidelines for optimization of the preform impregnation conditions for a given material configuration.

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Section: Capillary Phenomena and Micro-impregnationsupporting

confidence: 68%

Section: Matrix Materialsmentioning

confidence: 99%

Impregnation of Compressible Fiber Mats with a Thermoplastic Resin. Part II: Experiments

Michaud¹,

Törnqvist²,

Månson

2001

Journal of Composite Materials

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“…The fibre surface is clean and there are no PP residuals on fibre surface which indicates that interface is the weakest link in these composites. Figure 13 (b) shows that in some regions fibres were impregnated whereas some regions contain PP only [24,25].…”

Section: Composite Materials Microstructure and Qualitymentioning

confidence: 95%

Mechanical Performance of a Recycled Carbon Fibre/PP Composite

2010

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A composite made of recycled carbon fibres in recycled polypropylene matrix is studied experimentally to describe the features of the elastic and time dependent nonlinear mechanical behaviour. The properties of the developed material have a large variability to be addressed and understood. It was found that the stress-strain curves in tension are rather nonlinear at low strain rate and the strength is sensitive to strain rate. The elastic properties' reduction for this composite after loading to high strains is rather limited. More important is that even in the "elastic region" due to viscoelastic effects the slope of loadingunloading curve is not the same and that at higher stress large viscoplastic strains develop and creep rupture is typical. The time and stress dependence of viscoplastic strains was analysed and described theoretically. The viscoelastic response of the composite was analysed using creep compliance, which was found to be slightly nonlinear.

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“…The Laplace transform of compliance functions can be calculated using Equation (43) and the engineering constants for the matrix in the Laplace domain can be calculated using Equations (32). Then the engineering constants for UD composite in the Laplace domain can be calculated using Equations (A2.1)-(A2.9) and the element of compliance and stiffness matrices for UD composite using Equations (A1.3) and Equation (7). Stiffness and compliance for GMT in the Laplace domain are calculated using Equations (25) and (31).…”

Section: Resultsmentioning

confidence: 99%

“…It is explained in Reference [4] by insufficient wetting of PP into glass fiber and poor fiber-matrix adhesion from heat treatment of the fibers. Elmendorp [7] states that a clear disadvantage of the polypropylene (PP) is its small degree of polarity, which leads to limited wettability as well as to adhesion issues in its use as a matrix material for composite materials such as glass mat thermoplastics. It can result in unwetted areas, voids, etc.…”

Section: Introductionmentioning

confidence: 99%

Micromechanical Modeling of Viscoelastic Response of GMT Composite

Megnis

Vārna

Allen³

et al. 2001

Journal of Composite Materials

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Experimental studies have been performed to obtain creep compliance functions of polypropylene (PP) and Glass Mat reinforced Thermoplastics (GMT) with PP matrix. It was found that both GMT and PP in the considered loading region may be considered as linear viscoelastic materials. The obtained viscoelastic compliance functions were successfully used to describe material behavior in the stress relaxation test. A micromechanical model based on the correspondence principle in the Laplace domain was developed to describe the viscoelastic behavior of GMT. This model considers the GMT composite with a given fiber orientation distribution function as consisting of an infinite number of unidirectional layers with orientations corresponding to this distribution function. The viscoelastic properties of the unidirectional layer are calculated using Hashin's concentric cylinder model that uses the experimentally determined viscoelastic properties of PP matrix. The predictions for GMT have been compared with experimental data. The model predicts rather good initial properties of GMT but it gives slightly less time dependence than compared to experimental data for both relaxation functions and compliance. The cause of the difference (debonding) between matrix and fiber, nonuniform fiber spatial distribution, stress concentrations etc.) is discussed.

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Some wetting and adhesion phenomena in polypropylene composites

Cited by 8 publications

References 16 publications

Impregnation of Compressible Fiber Mats with a Thermoplastic Resin. Part II: Experiments

Impregnation of Compressible Fiber Mats with a Thermoplastic Resin. Part II: Experiments

Mechanical Performance of a Recycled Carbon Fibre/PP Composite

Micromechanical Modeling of Viscoelastic Response of GMT Composite

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