Julien Ville

Rheological, morphological and structural properties of PE/PA/nanoclay ternary blends: Effect of clay weight fraction

The effect of an organically modified layered silicate on the rheological, morphological, and structural properties of immiscible polyethylene/polyamide (PE/PA) blends was investigated. The blends have been prepared for PA weight fractions ranging from 10 to 90% and at clay weight fractions from 1 to 6%. Scanning electron microscopy and transmission electron microscopy have been used to study the morphology and the structure of the blends. The dispersed phase size was shown to decrease with increasing clay content up to 2% and tends to stabilize at higher fractions. For PE matrix blends, clay particles were shown to be essentially located at the interface of the two polymers, forming an interphase whose thickness grows with clay fraction. For PA matrix blends with 2% of clay, the interphase thickness is stabilized at 11 nm; further clay addition leads to dispersion of clay within PA. Oscillatory and steady shear measurements have shown that PE matrix ternary blends behaved like polymer blends and underlined the contribution of an interphase at high clay fractions. For sufficiently filled PA matrix blends, a yield behavior was observed. The behavior of PA matrix ternary blends, dominated by the organoclay dispersed in PA, is similar to that of nanocomposites.The effect of an organically modified layered silicate on the rheological, morphological, and structural properties of immiscible polyethylene/polyamide (PE/PA) blends was investigated. The blends have been prepared for PA weight fractions ranging from 10 to 90% and at clay weight fractions from 1 to 6%. Scanning electron microscopy and transmission electron microscopy have been used to study the morphology and the structure of the blends. The dispersed phase size was shown to decrease with increasing clay content up to 2% and tends to stabilize at higher fractions. For PE matrix blends, clay particles were shown to be essentially located at the interface of the two polymers, forming an interphase whose thickness grows with clay fraction. For PA matrix blends with 2% of clay, the interphase thickness is stabilized at 11 nm; further clay addition leads to dispersion of clay within PA. Oscillatory and steady shear measurements have shown that PE matrix ternary blends behaved like polymer blends and underlin...

Influence of extrusion conditions on fiber breakage along the screw profile during twin screw compounding of glass fiber-reinforced PA

Abstract In the present study, Polyamide 12 was compounded with glass fibers in both laboratory and industrial twin screw extruders using various processing conditions (screw speed and feed rate). Dead-stop experiments were performed and samples were collected at different locations along the screws in order to determine the fiber length distribution and the extent of fiber breakage. Results show that significant fiber break-up occurs right after the addition of glass fibers to the molten matrix. Similarly fiber length distribution changes drastically at the first sampling location, near the glass fiber feeder. Processing conditions also influence the extent of degradation: it increases with screw speed and decreases with feed rate, which controls the residence time. Flow modelling has been used to calculate the flow conditions along the screw profile. It is shown that the modified Shon-Liu-White model previously proposed to describe the average fiber length evolution as function of specific energy is not able to correctly predict the evolution along the screw profile. In similar processing conditions, the large industrial extruder appears as less severe than the small laboratory one.

A Study of Fiber Breakage during Compounding in a Buss Kneader

Abstract This paper is devoted to the study of fiber breakage during compounding with a polyamide matrix in a Buss kneader. Results showed a drastic decrease of glass fiber length during compounding, typically from 3500 to 350 μm. Fiber breakage depended on processing conditions: it increased with screw speed, but the effect of feed rate was less clear. Fiber breakage increased also with the severity of the screw profile. Characterizations of fiber length evolution along the screw profile have also been performed after dead-stop experiments. Generally speaking, fiber length evolution can be described using a modified Shon-Liu-White model, in which either the number of turns or the specific energy is considered.

3D printed ferromagnetic composites for microwave applications

The use of 3D technology in the field of microwave electronics requires the development of new materials adapted to these applications. In this study, magnetic composites composed of polyethylene (PE) matrix filled with Nickel–Iron alloy (Ni81Fe19) are prepared using two elaboration devices: first, a propeller mixer for small quantity of samples, and then, a twin screw extruder able to produce higher samples amounts. Microstructural and rheological characterizations are suggested in order to study the feasibility of shaping PE/NiFe composites with 3D printer using Fused Deposition Modeling technique. A shear-thinning behavior with the dispersion of NiFe micrometric particles allows the use of 3D printer to shape final composites. A microwave characterization is also performed. Electromagnetic properties are predicted by the adjustment of a model based on mixing laws taking into account demagnetization effect and interactions between NiFe particles. The production of composite filaments and first printing tests are also presented.

A Comparative Study of Fiber Break‐up During Compounding of Glass Fiber‐Reinforced Polyamide in Batch and Continuous Mixers

Glass fiber breakage during compounding was determined for both batch and continuous mixers including an internal mixer and two different co‐rotating twin screw extruders; of laboratory and industrial scales. The effect of processing conditions such as screw speed, feed rate and screw profiles on fiber damage was investigated. Finally, the results of experimental studies were discussed, compared and interpreted using a model for fiber breakage.