Structure-property relationships in glass-reinforced polyamide, part 1: The effects of fiber content

Abstract

We present the results of an extensive study of the performance of injection moulded glass-fibre reinforced polyamide 66 with glass content between 0-40% and based on two chopped glass products both sized with polyamide compatible sizing. Mechanical properties generally improved with increasing glass content, modulus linearly, strength with a maximum at 40-50% glass content, and impact showing an initial decrease from the resin value with a minimum at 4% glass content before increasing at higher glass contents. Residual fibre length decreased linearly with increasing glass content. Interfacial strength was found to be in the 30-36 MPa range and no significant differences in dry as moulded performance was found between the 123D and 173X sizings. Conditioning these composites in either boiling water or water/glycol mixtures leads to a dramatic drop in both tensile modulus and tensile strength. This is most likely due to the high level of matrix plasticization. After conditioning the 173X sized glass delivered a significantly higher level of tensile elongation at all fibre contents. Excellent agreement was obtained between the experimental data and the theoretical predictions of the Cox model for modulus and the Kelly-Tyson model for strength over the range of fibre concentrations studied.

Optimization of the crystallinity of polypropylene/submicronic-talc composites: The role of filler ratio and cooling rate

“…The combination of this crystallographic characteristic of the talc platelets and their nucleating effect results in an orientation of the iPP crystals nearly normal to the talc platelets [23][24][25][26][27]. This concomitance of orientation of the chains and the talc platelets is a common feature of injectionmolded composites reinforced with filler of high aspect ratio which tend to align along the flow direction [27,33,[55][56][57]. In the case of composites with lamellar fillers, this phenomenon is enhanced by to the so-called shear-amplification effect [58].…”

Prediction of Young’s Modulus for Injection Molded Long Fiber Reinforced Thermoplastics

“…At higher fiber content, the dominant fiber breakage mechanisms are fiber-fiber and fiber-machine interactions [34]. The residual fiber length exhibited a linear decrease following an increase in the fiber content [14,35]. Several authors also suggested that the fiber breakage rate was proportional to the fiber length or fiber aspect ratio [12,36].…”

“…The predicted values keep increasing with the fiber content, which is not true within commercial fiber concentration for injection molded LFTs [13,14]. In this paper, we report on the development of an empirical model to correct the fibers' aspect ratio for the actual as-formed LFTs with fiber bundles under high fiber content.…”

Influence of Hygrothermal Aging on Poisson’s Ratio of Thin Injection-Molded Short Glass Fiber-Reinforced PA6

“…The mechanical properties of glass fiber-reinforced polyamide materials, in general, depend on glass fiber content, glass fiber diameter and glass fiber length (aspect ratio), as well as the glass fiber orientation [1][2][3]. The glass fiber orientation is generated mainly by the injection molding process and can be determined visually or by X-ray diffraction analysis [4,5].…”

“…The Poisson's ratio µ describes the ratio of transverse strain εq to tensile strain εl under uniaxial mechanical stress (see Equation (2)) and is given in some common standard publications as a material-specific constant [9,10]. A value of Poisson's ratio µ of 0.5 means incompressible material behavior and, thus, isotropy under uniaxial load [11].…”