Lightweight and High Impact Toughness PP/PET/POE Composite Foams Fabricated by In Situ Nanofibrillation and Microcellular Injection Molding

Abstract

Polypropylene (PP) has become the most promising and candidate material for fabricating lightweight products. Microcellular injection molding (MIM) is a cost-effective technology for manufacturing porous plastic products. However, it is still challenging to fabricate high-performance PP microcellular components. Herein, we reported an efficient strategy to produce lightweight and high impact toughness foamed PP/polyethylene terephthalate (PET)/polyolefin-based elastomer (POE) components by combining in situ fibrillation (INF) and MIM technologies. First, the INF composite was prepared by integrating twin-screw compounding with melt spinning. SEM analysis showed PET nanofibrils with a diameter of 258 nm were achieved and distributed uniformly in the PP due to the POE’s inducing elaboration effect. Rheological and DSC analysis demonstrated PET nanofibrils pronouncedly improved PP’s viscoelasticity and crystal nucleation rate, respectively. Compared with PP foam, INF composite foam showed more stretched cells in the skin layer and refined spherical cells in the core layer. Due to the synergistic toughening effect of PET nanofibrils and POE elastic particles, the impact strength of INF composite foams was 295.3% higher than that of PP foam and 191.2% higher than that of melt-blended PP/PET foam. The results gathered in this study reveal potential applications for PP based INF composite foams in the manufacturing of lightweight automotive products with enhanced impact properties.

In Situ Nanofibrillar Polypropylene-Based Composite Microcellular Foams with Enhanced Mechanical and Flame-Retardant Performances

“…The rheological property of polymer composite has a significant effect on foaming behavior [ 36 ]. Figure 3 illustrates the relationship between storage modulus (G′), complex viscosity (η*) and loss tangent (tan δ) with frequency (ω).…”

“…η* of INF composites is significantly higher than that of pure PP and melt-blended composites, particularly in the low frequency region. It can be explained that the PET fibril network can restrict the motion of PP molecular chains as a role of a skeleton within PP matrix [ 36 ]. It is noteworthy that the η* of PP/PET(S) composite decreased greatly after the introduction of PDPP particles, while the η* is almost kept constant for both INF composites.…”

Lightweight and High Mechanical Properties of In Situ Poly(ethylene terephthalate) Reinforced Polypropylene Composite Foams by Chemical Foam Injection Molding

“…This result is consistent with our previous works. 21,27 The immiscible nature of the PET phase and PP matrix, associated with strong elongation flow action during the INF process, are major factors influencing the formation of the fibrillar network. Additionally, the average diameter of PET fibrils in the PP/PET(F)/Talc composite is significantly reduced from 368 to 231 nm when compared with the PP/PET(F) sample.…”

Enhancing the foaming properties of polypropylene/basalt fiber composites by altering their rheological and crystallization behavior via polyethylene–octene blending modification

“…In a PP composite, it is crucial to consider that the disperse phase has a small and evenly distributed particle size. Any changes in the morphology of the dispersed phase can affect the nucleation effect, which in turn affects the foam's quality 23,24 . Such as Wang et al 25 prepared PP/POE composites with “island” structure and co‐continuous structure.…”

“…Any changes in the morphology of the dispersed phase can affect the nucleation effect, which in turn affects the foam's quality. 23,24 Such as Wang et al 25 prepared PP/POE composites with "island" structure and co-continuous structure. Gong et al 26 found that the addition of POE could obviously enhance the foaming quality of PP.…”