Fibre Production and Measurement

Raw Materials for Fibre Production

Raw materials for producing virgin PP, recycled PP and HDPE used in this study are commercial grade granules. Their characteristics given in the manufacturer specifications are presented in Table 3.1 (LyondellBasell 2013; Martogg 2013; PTTPM 2013).

© Springer Nature Singapore Pte Ltd. 2017

S. Yin, Development of Recycled Polypropylene Plastic Fibres

to Reinforce Concrete, Springer Theses, DOI 10.1007/978-981-10-3719-1_3

Table 3.1 Characteristics of raw materials of plastic fibres

Raw material

Virgin PP granule

Recycled PP granule

HDPE granule

Density (g/cm3)




Melt flow index (MFI, 2.16 kg, dg/min)

3.5 (at 230 °C)

13 (at 230 °C)

0.4 (at 190 °C)

Tensile stress at yield (MPa)




Flexural modulus (GPa)




Notched izod impact strength (23 °C, type 1, Notch A, kJ/m2)




Preparation of PP Fibres

As shown in Fig. 3.1, the plastic granules were fed into a single-screw extruder and melted. Temperatures of five heating zones of the extruder were set at 218, 223, 225, 233 and 235 °C. Fibres were then extruded into a water bath from the nozzle at the tip of the extruder. The extruded fibers are pulled to a chill roll and hot-drawn in the ovens at 120-150 °C. The resulting fibres through the second chill roll were smooth and had a circular cross-section of around 0.9 mm2. An indented roller die was used to mark indents on the fibres, in order to increase the bonding strength between the fibres and concrete. After indentation, fibers were cut into a length of 47 mm. Table 3.2 lists the virgin and recycled PP fibres produced through this

Extrusion apparatus for monofilaments

Fig. 3.1 Extrusion apparatus for monofilaments

Table 3.2 Details of PP fibres



100% virgin PP fibre

100% virgin PP

5:95 HDPE-virgin PP fibre

Mixture of 5% of HDPE and 95% virgin PP

100% recycled PP fibre

100% recycled PP

5:95 HDPE-recycled PP fibre

Mixture of 5% of HDPE and 95% recycled PP

50:50 virgin-recycled PP fibre

Mixture of 50% of virgin PP and 50% recycled PP

method. They were 100% virgin PP fibre, 5:95 HDPE-virgin PP fibre, 100% recycled PP fibre, 5:95 HDPE-recycled PP fibre, and 50:50 virgin-recycled PP fibre. Their details can be seen in Table 3.2.

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