Fiber preparation and mechanical properties of recycled polypropylene for reinforcing concrete

Abstract

Polypropylene (PP) fibers have been widely used to reinforce concrete footpaths as an alternative to steel mesh. The reinforcing effect of the PP fiber is directly proportional to its tensile strength and Young modulus. This research explored the feasibility of using an improved melt spinning and hot drawing process to produce virgin and recycled PP fibers of high mechanical properties in an industrial scale. Commercial grade granules of virgin PP, recycled PP and HPDE were mixed in different proportions in preparing five different types of fibers. All the fibers obtained high tensile strength and Young modulus. A relationship between the structural parameters and mechanical properties was then established. It was observed that the melt spinning and hot drawing process formed both a-form and b-form crystals in the PP fibers, and significantly improved crystallinity from about 50% to 80%.

Mechanical reprocessing of polyolefin waste: A review

“…It refers to blend recycled plastics with similar type of virgin plastics or different types of recycled plastics in the melt process. Blending recycled plastics with virgin plastics of similar components not only can reduce cost, but the new blended plastics can maintain equal performance with the virgin plastic products . However, plastic waste collected from kerbside is a mixture of various types and qualities of polymers, thus extensive research has been carried out on reprocessing commingled plastic waste .…”

Dispersion of carbon nanotubes in ultrahigh‐molecular‐weight polyethylene by melt mixing dominated by elongation stress

“…These results are in accordance with those of our earlier studies. 13,19 From Figure 6 presents SEM and TEM images of CNTs/UHMWPE composites prepared at various rotation rates with a CNT content of 1 wt%. The mixing time is fixed at 4 min.…”

“…The structure and working principle of the feeding unit and the mixing unit were introduced in detail in our previous studies. 19,20 The feeding unit and the mixing unit are connected with a baffle. Materials can only flow from the feeding unit into the mixing unit through the flow gap on the baffle but cannot flow back.…”

Characterisation of macro polyolefin fibre reinforcement in concrete through round determinate panel test

“…It has a length of 30-60 mm and a cross section of 0.6-1.5 mm 2 . It has a tensile strength of 300-600 MPa and a Young's modulus of 4-10 GPa depending upon the manufacturing techniques [3]. Two techniques have been widely adopted to produce macro polyolefin fibre.…”

“…Concrete has very high compressive strength, but it is weak in tensile strength and toughness. In order to improve its tensile strength and toughness, steel reinforcement [1] and various fibres such as steel fibres [2], synthetic fibres [3], glass fibres [4] and natural fibres [5] are often used to reinforce concrete.…”