Distribution of α-, β-, and γ-Phases in a Multi-flow Injection-molded Hierarchical Structure

Mi, Dashan; Hou, Fengyi; Zhou, Man; Zhang, Jie

doi:10.1007/s10118-018-2057-3

Cited by 7 publications

(7 citation statements)

References 54 publications

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“…As the amorphous phase is made up of rigid and loose parts [21] , and the rigid part is comparably difficult to remove by acid, the remaining phase that can be observed by SEM may not just be the kebab lamella but may also some rigid amorphous structure. However, in our previous work, using online WAXD/ SAXS detection, we proved that shish-kebab structure recrystallization at 165 C could lead to a 10% increase in kebab thickness, which is consistent with the phenomenon found in the current experiment [24] . Two major mechanisms can explain lamellar thickening: the meltingrecrystallization mechanism (recrystallization after partial melting) and the sliding diffusion mechanism (polymer chains in the lamella crystal slide along the chain axis) [31,32] .…”

Section: Crystalline Structuresupporting

confidence: 91%

Further improved mechanical properties of polypropylene by shish‐kebab structure and high‐temperature annealing

Zhao

Jia

2022

Polymer Engineering & Sci

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Multiflow injection molding is used to prepare a highly oriented shish-kebab structure, and the mechanical properties of Polypropylene in the weak direction (WD) and strong direction (SD) are analyzed in this work. The oriented structure shows strong anisotropy. For example, the impact strength in SD is 6 times that of WD. One or three minutes of high-temperature-annealing (HTA, 30 C higher than T m ) has been proven to be an effective method to trigger the partial melting and re-crystallization process, which in turn, can improve the shish-kebab structure and greatly improve yield and impact strength in both WD and SD. Furthermore, results confirm that the chains in the amorphous region play a key role in the mechanical properties in the WD, while the shish-kebab crystal structure determines the properties in the SD. Using shish-kebab structure and HTA to improve mechanical properties in both SD and WD directions will be helpful to avoid generating fiber composites that create recycling difficulties and loss of properties with cycle times.

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Section: Crystalline Structuresupporting

confidence: 91%

Further improved mechanical properties of polypropylene by shish‐kebab structure and high‐temperature annealing

Zhao

Jia

2022

Polymer Engineering & Sci

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“…It is well-known that iPP can crystallize into two distinctly different crystal morphologies under different conditions, namely spherulites and shish-kebab superstructures. The formation of spherulites is under quiescent crystallization conditions, while shish-kebabs under intensive shear or elongational flow condition. − Shish-kebab, which is regarded as a kind of self-reinforced superstructure, can pronouncedly improve impact strength of the materials without sacrificing stiffness and modulus, unlike the addition of elastomer. − …”

Section: Introductionmentioning

confidence: 99%

Remarkably Improved Impact Fracture Toughness of Isotactic Polypropylene via Combining the Effects of Shear Layer-Spherulites Layer Alternated Structure and Thermal Annealing

Liu

Hong

et al. 2019

Ind. Eng. Chem. Res.

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The effect of thermal annealing on the mechanical properties and microstructure of polymers has been studied intensively. Nevertheless, sparse work investigated the influence of annealing on the mechanical properties of materials with alternated structure. In this work, the evolution of properties and microstructure of iPP samples with different structure after annealing were discussed. Note that annealing plays a little role on microstructure of all the specimens, whereas its effect on the variation of impact strength of different samples does not show the similar trend. For sample CIM and V1, impact fracture toughness does not improve significantly after annealing within the range of temperature used. But the promotion of the impact strength of sample V2 is extremely remarkable (from 29 KJ/m2 to 90.5KJ/m2), which can be attributed to better interfacial adhesion, resulting in violent crack deflection and plastic deformation, the formation of microfibers and the better ability of load transfer.

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“…The control of semicrystalline polymer morphology has received much attention due to the “structure–property” relationship, which plays a crucial role in both scientific study and industrial field. Generally, the morphology is largely decided by processing conditions such as thermal field and shear field. − For example, the thermal field can influence mobility of chain and a sufficient shear effect can cause its extension.…”

Section: Introductionmentioning

confidence: 99%

Evolution of iPP/HDPE Morphology under Different Mold Temperatures via Multiflow Vibration Injection Molding: Thermal Field Simulation and Oriented Structures

Hong

Leng

et al. 2020

Ind. Eng. Chem. Res.

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To date, many advanced polymer processing technologies have been developed to tune the morphology of semicrystalline polymers, such as multiflow vibration injection molding (MFVIM). By adjusting the processing fields, i.e., shear and thermal fields, the material can be imparted with great mechanical properties, good electrical/thermal conductivity, or biomimic structure, by manipulating chain's orientation, crystal's arrangement, or hierarchical structure distribution. Despite the era of intelligent manufacturing approaching, there is rarely any report on the computer simulation of these advanced processing technologies. In this work, the processing fields of the MFVIM isotactic polypropylene/high-density polyethylene (iPP/ HDPE) part are successfully simulated using Moldflow by designing a special model. Different thermal gradients can be realized in the plate part by setting different mold temperatures. The experimental results correlate well with the simulation results, and both of them illustrate that the mold temperature plays an important role in the morphology of dispersed PE phase resulting in different physical properties.

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Distribution of α-, β-, and γ-Phases in a Multi-flow Injection-molded Hierarchical Structure

Cited by 7 publications

References 54 publications

Further improved mechanical properties of polypropylene by shish‐kebab structure and high‐temperature annealing

Further improved mechanical properties of polypropylene by shish‐kebab structure and high‐temperature annealing

Remarkably Improved Impact Fracture Toughness of Isotactic Polypropylene via Combining the Effects of Shear Layer-Spherulites Layer Alternated Structure and Thermal Annealing

Evolution of iPP/HDPE Morphology under Different Mold Temperatures via Multiflow Vibration Injection Molding: Thermal Field Simulation and Oriented Structures

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