Isothermal and Non-Isothermal Crystallization Studies of Long Chain Branched Polypropylene Containing Poly(ethylene-co-octene) under Quiescent and Shear Conditions

Zhang, Zinan; Yu, Fengyuan; Zhang, Hongbin

doi:10.3390/polym9060236

Cited by 16 publications

(9 citation statements)

References 64 publications

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“…Already crystallized inclusions of a dispersed polymer accelerate the crystallization of the matrix acting as nucleating agent and induce the formation of additional spherulites. Finally, the average spherulite radius in those blends becomes smaller than in plain iPP crystallized under the same condition [22]. Razavi-Nouri et al [23] studied the morphology of PP/linear low-density PE (LLDPE) blends and found that the nucleation densities of the PP spherulites decreased in the presence of the LLDPE.…”

Section: Introductionmentioning

confidence: 99%

Recycling of Polypropylene/Polyethylene Blends: Effect of Chain Structure on the Crystallization Behaviors

Rudolph²,

2019

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The combination of high-density polyethylene (HDPE), low-density polyethylene (LDPE) and polypropylene (PP) is frequently found in polymer waste streams. Because of their similar density, they cannot be easily separated from each other in the recycling stream. Blending of PP/ polyethylenes (PEs) in different ratios possibly eliminate the sorting process used in the regular recycling process. PP has fascinating properties such as excellent processability and chemical resistance. However, insufficient flexibility limits its use for specific applications. Blending of PP with relative flexible PEs might improve its flexibility. This is a unique approach for recycling or upcycling, which aims to maintain or improve the properties of recycled materials. The effects of the branched-chain structures of PEs on the crystallization behavior and the related mechanical properties of such blends were investigated. The overall kinetics of crystallization of PP was significantly influenced by the presence of PEs with different branched-chain structures. The presence of LDPE was found to decrease the overall crystallization rate while the addition of HDPE accelerated the crystallization process of the blends. No negative effect on the mechanical performance and the related crystallinity was observed within the studied parameter range.

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Section: Introductionmentioning

confidence: 99%

Recycling of Polypropylene/Polyethylene Blends: Effect of Chain Structure on the Crystallization Behaviors

Rudolph²,

2019

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“…This type of process offers very short reaction times, little or no use of solvents, simple product isolation steps, and relatively low infrastructure costs [11,12]. In the literature, PP-LCB is a well-studied topic with different approaches to improve the properties of linear PP and their disadvantages [13][14][15][16][17][18][19][20][21][22]. In addition to introducing LCB onto the backbone of PP, further competition reactions can take place.…”

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confidence: 99%

Influence of Different Types of Peroxides on the Long-Chain Branching of PP via Reactive Extrusion

et al. 2020

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Long-chain branching (LCB) is known as a suitable method to increase the melt strength behavior of linear polypropylene (PP), which is a fundamental weakness of this material. This enables the modification of various properties of PP, which can then be used—in the case of PP recyclates—as a practical “upcycling” method. In this study, the effect of five different peroxides and their effectiveness in building LCB as well as the obtained mechanical properties were studied. A single screw extruder at different temperatures (180 and 240 °C) was used, and long-chain branched polypropylene (PP-LCB) was prepared via reactive extrusion by directly mixing the peroxides. The peroxides used were dimyristyl peroxydicarbonate (PODIC C126), tert-butylperoxy isopropylcarbonate (BIC), tert-Butylperoxy 2-ethylhexyl carbonate (BEC), tert-amylperoxy 2-ethylhexylcarbonate (AEC), and dilauroyl peroxide (LP), all with a concentration of 20 mmol/kg. The influence of the temperature on the competitive prevalent reactions of degradation and branching was documented via melt mass-flow rate (MFR), rheology measurements, and gel permeation chromatography (GPC). However, via extensional rheology, strain hardening could be observed in all cases and the mechanical properties could be maintained or even improved. Particularly, PODIC C126 and LP signaled a promising possibility for LCB in this study.

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“…They further analyzed the effect of molecular weight of EOC on the crystallization rate of PP matrix in another piece of research 26 . The crystallization behavior of the PP/EOC blends was also studied by Zhang et al 27 They found that the crystallization of the blends was considerably enhanced due to the presence of the long‐chain branches and showed that the addition of EOC could also increase the crystallization rate of PP. Moreover, the results reported by Uthaipan et al 28 revealed that in comparison with the neat PP, the PP crystallization in the PP/EOC blends happened at a lower degree of undercooling with smaller crystal size and vulcanized EOC particles could accelerate the crystallization of the PP phase.…”

Section: Introductionmentioning

confidence: 99%

Toward understanding the crystallization behavior of polypropylene‐based nanocomposites: Effect of ethylene–octene copolymer and nanoclay localization

et al. 2023

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The crystallization properties of polypropylene (PP), a widely used polymer in industry, can be modified to overcome its mechanical limitations. In the current work, we investigated the effect of ethylene octene copolymer (EOC), blend morphology, nanoclay loading, nano‐localization, and component ratios on PP/EOC crystallization behavior in various aspects, including crystallization rate, degree of crystallinity, nucleation state, and crystalline phases. The results revealed that adding EOC with varying ratios can decrease PP crystallinity both in degree and rate due to the partial miscibility of components through grafting. Furthermore, it was found that the effect of the nanoclay on the crystallization behavior of PP is dependent on the nanoclay loading and its localization in the blend. The nanoclay, therefore, served as a nucleation agent at low nanoparticle contents, accelerating the crystallization rate regardless of the blend's microstructure. However, the crystallization rate of the blend samples at high nanoclay contents (above the rheological percolation threshold) was strongly influenced by the type of morphology. Accordingly, high nanoclay concentrations in blends with matrix‐dispersed morphologies reduced crystallization rates (increasing half‐time from 164 to 216 and 186 s), primarily because PP chains slowed down due to their interactions with nanoparticles and nanoclay hindrance. In contrast, in a blend with a co‐continues‐type morphology, the crystallization rates increased (decreasing half‐time from 624 to 270 and 236 s) due to nano‐localization at the interface and morphology transformation to the matrix‐dispersed one. The blends and nanocomposites based on PP/EOC were also investigated to determine the relationship between the crystallization behavior and mechanical properties.

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Isothermal and Non-Isothermal Crystallization Studies of Long Chain Branched Polypropylene Containing Poly(ethylene-co-octene) under Quiescent and Shear Conditions

Cited by 16 publications

References 64 publications

Recycling of Polypropylene/Polyethylene Blends: Effect of Chain Structure on the Crystallization Behaviors

Recycling of Polypropylene/Polyethylene Blends: Effect of Chain Structure on the Crystallization Behaviors

Influence of Different Types of Peroxides on the Long-Chain Branching of PP via Reactive Extrusion

Toward understanding the crystallization behavior of polypropylene‐based nanocomposites: Effect of ethylene–octene copolymer and nanoclay localization

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