Relationship between fiber degradation and residence time distribution in the processing of long fiber reinforced thermoplastics

Zhuang, Hao; Ren, P.; Zong, Yanbing; Dai, Guohao

doi:10.3144/expresspolymlett.2008.68

Cited by 21 publications

(17 citation statements)

References 14 publications

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“…The effect of processing parameters on fiber length distribution during extrusion has been widely investigated, including melt viscosity [3], screw speed [4], screw geometry [5]and residence time [6]. However, studies on the effect that the ratio of initial pellet length to screw channel width, or diameter, has on the percent of fiber breakage during polymer processing are seldom reported.…”

Section: Introductionmentioning

confidence: 99%

Progress in modeling long glass and carbon fiber breakage during injection molding

Chen¹,

Cieslinski²,

Baird³

2015

AIP Conference Proceedings

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Abstract. This work is concerned with the modeling of in-machine fiber breakage during injection molding. A lab-scale single screw extruder is used to evaluate fiber breakage in the screw. Our experiments show that as the initial glass fiber pellets length is reduced relative to the channel width, the overall percent of breakage is reduced. We believe that the ratio of initial pellet length to the screw channel width, or diameter, is an important parameter determining the percent of fiber breakage. Data have been fit using an exponential decay model with a kinetic decay constant and a critical length value. This empirical model has been tested on an injection molding machine with a screw 1.6 times larger than that of our single screw extruder. The predicted average fiber length leaving the nozzle shows reasonable agreement with the measured value. For the injection molded end-gated-plaque produced by the same machine, additional fiber breakage has been observed in the runner. A hydrodynamic force based breakage model is combined with mold filling simulation to simulate the fiber breakage in the runner. For carbon fibers, similar breakage trends were observed in the single screw extruder indicating the applicability of our empirical model to carbon fiber.

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Section: Introductionmentioning

confidence: 99%

Progress in modeling long glass and carbon fiber breakage during injection molding

Chen¹,

Cieslinski²,

Baird³

2015

AIP Conference Proceedings

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“…One of the most significant problems of injection‐molded composites is the fiber fragmentation. Mainly in the compounding extruder and in the feed zone of the injection molding screw the strong shearing stresses reduce the length of glass fibers to the order of magnitude of a few tenths millimeters, regardless of their original size [5–7]. Since the enlargement of residual fiber length in the composite products can significantly enhance the mechanical and physical properties of injection‐molded composites, numerous technologies have been developed in the industry for producing parts in which the residual fiber length exceeds the usual values of a few tenths millimeters [4, 8, 9].…”

Section: Introductionmentioning

confidence: 99%

Manufacturing and testing of long basalt fiber reinforced thermoplastic matrix composites

Deák

Czigány

Maršálková

et al. 2010

Polymer Engineering & Sci

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In this work, long basalt fiber reinforced composites were investigated and compared with short basalt fiber reinforced compounds. The results show that long fiber reinforced thermoplastic composites are particularly advantageous in the respects of dynamic mechanical properties and injection molding shrinkage. The fiber orientation in long basalt fiber reinforced products fundamentally differs from short basalt fiber reinforced ones. This results in more isotropic molding shrinkage in case of long basalt fiber reinforced composites. The main advantage of the used long fiber thermoplastic technology is that the special long fiber reinforced pellet can be processed by most conventional injection molding machines. During extrusion compounding the fibers in the compound containing 30 wt% fibers are fragmented to an average length of 0.48 mm (typical of short fiber reinforced thermoplastic compounds), this length decreases further during injection molding to 0.20 mm. Contrarily using long fiber reinforced pellets and cautious injection molding parameters, an average fiber length of 1.8 mm can be achieved with a conventional injection molding machine, which increased the average length/diameter ratio from 14 to 130. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers

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“…It was clear that the PA46 macromolecules were degraded by extrusion. 18,19 Average length of glass ber ( L) and its distribution The CC and M V of PA46 were 8.06 Â 10 À5 mol g À1 and 3.62 Â 10 4 for RPA46-F6.…”

Section: Resultsmentioning

confidence: 99%

“…They found that the composite mixed with a Buss kneader had shorter average ber length than that one mixed with a twin screw extruder. Zhuang et al 19 investigated the inuence of shear force with different screw speeds and variable channel depth on ber degradation. Ville et al 17 studied ber breakage during compounding with a polyamide matrix in a Buss kneader.…”

Section: Introductionmentioning

confidence: 99%

Relationship between screw structure and properties of recycled glass fiber reinforced flame retardant nylon 46

et al. 2015

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Considering environmental protection and economic requirements, the use of recycled glass fiber reinforced flame retardant nylon 46 (RGFFRPA46) is of significant importance. In this work, the mechanical, thermal, rheological and flame retardant properties of the recycled RGFFRPA46 were evaluated by varying shear screws. To establish the relationship between the screw structure and the properties of RGFFRPA46, the carboxyl content (CC) and viscosity-average molecular weight (M V ) of PA46, the distribution and average length of glass fiber ( L) and microscopic appearance of RGFFRPA46 were investigated. The results showed that the shear force resistance time of RGFFRPA46 increased with the increase of the shear strain and with the ratio of length to diameter of the used extruder. As a result, M V of PA46, L and the percentage of glass fiber length (V j ), which was higher than critical length, decreased, whereas the CC of PA46 increased significantly. The mechanical and rheological properties were sensitive to these variations, particularly the decrease in impact, tensile, flexural strength and shear viscosity of RGFFRPA46. Furthermore, the influence of degradation on M V of PA46 and L were negative to the thermal properties of RGFFRPA46 after extrusion. However, the flame retardant properties of RGFFRPA46 were independent of the degradation. All of them achieved a UL-94 V-0 classification, and passed the glow wire ignition temperature (775 C) test along with LOI of 36.7%. When RGFFRPA46 was extruded by a single screw extruder with the lowest shear force, a decrease of only 5.8% was observed in mechanical properties with negligible reductions in thermal and flame retardant properties.

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Relationship between fiber degradation and residence time distribution in the processing of long fiber reinforced thermoplastics

Cited by 21 publications

References 14 publications

Progress in modeling long glass and carbon fiber breakage during injection molding

Progress in modeling long glass and carbon fiber breakage during injection molding

Manufacturing and testing of long basalt fiber reinforced thermoplastic matrix composites

Relationship between screw structure and properties of recycled glass fiber reinforced flame retardant nylon 46

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