Shish–kebab-like cylindrulite structures resulted from periodical shear-induced crystallization of isotactic polypropylene

Zhou, Qixiong; Liu, Fanghui; Guo, Chao; Fu, Qiang; Shen, Kaizhi; Zhang, Jie

doi:10.1016/j.polymer.2011.05.002

Cited by 59 publications

(43 citation statements)

References 43 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…These technologies include shear-controlled orientation in injection molding, 18 oscillatory shear injection molding technology, 19 and vibrate-injection molding (VIM). 20 These methods provide a relatively thick sheared layer (or high sample orientation) for enhanced performance.…”

Section: Introductionmentioning

confidence: 99%

Quantification of the Effect of Shish-Kebab Structure on the Mechanical Properties of Polypropylene Samples by Controlling Shear Layer Thickness

Xia

Jin

et al. 2016

Macromolecules

Self Cite

View full text Add to dashboard Cite

Oriented "shish-kebab" structure can enable remarkable mechanical enhancement in polymers. Therefore, the formation mechanism and practical application of this structure have been extensively studied. However, the effect of shish-kebab content on mechanical properties is still uncertain. Knowledge of this effect is crucial in the academic and industrial fields but remains elusive because shish-kebab content is difficult to control. In this work, a self-developed multiflow vibrateinjection molding was used to produce samples with different shear layer thicknesses. The content of shish-kebab was represented by R, i.e., the thickness ratio of shear layer (composed by shish-kebab) to the whole sample. Results showed that with increased R impact/tensile strength exponentially increased, whereas elongation at break exponentially decreased. Based on the results, a modified model was proposed to interpret the strengthening and toughening mechanism. This study established a new method of predicting and controlling the mechanical properties of samples with shish-kebab and spherulite structures.

show abstract

Section: Introductionmentioning

confidence: 99%

Quantification of the Effect of Shish-Kebab Structure on the Mechanical Properties of Polypropylene Samples by Controlling Shear Layer Thickness

Xia

Jin

et al. 2016

Macromolecules

Self Cite

View full text Add to dashboard Cite

show abstract

“…Specifically, Ma‐PP was added to improve the interface adhesion of iPP and GF, and the β‐NA was used to modify the crystal form of the matrix. Furthermore, the self‐developed pressure vibrate‐injection molding (PVIM), whose mechanism was described in our previous papers , was adopted to form abundant orientation structures. Different from our previous works, a mold with an overflow channel was used to form multiflow in the sample during the packing stage.…”

Section: Introductionmentioning

confidence: 99%

Hierarchic structure and mechanical property of glass fiber reinforced isotactic polypropylene composites molded by multiflow vibration injection molding

Wang

et al. 2015

Polymer Composites

Self Cite

View full text Add to dashboard Cite

Maleic anhydride‐grafted polypropylene (Ma‐PP) and β nucleation agents (β‐NA) were used to modify the glass fiber (GF)/isotactic polypropylene (iPP) composite. The interface adhesion, degree of orientation, and crystalline morphologies of the PP/GF composites molded by multiflow vibrate‐injection molding (MFVIM) and conventional injection molding (CIM) were studied by polarized light microscopy (PLM), scanning electronic microscopy (SEM), and X‐ray measurements. Results prove that the interface adhesion was improved by the Ma‐PP; γ crystal was generated by the MFVIM due to the instant high pressure and shear during the multiflow; and a hierarchical structure which has a strengthened skin and a toughened core was formed. As a result, the final PP/GF/β‐NA composite has a 60% increase in tensile strength and 80% improvement in impact strength compare with the CIM pure PP/GF composite. Based on the observations, a modified model is proposed to interpret the strengthening and toughening mechanism. Our work paves the way to obtain high‐performance GF/iPP composites. POLYM. COMPOS., 38:2707–2717, 2017. © 2015 Society of Plastics Engineers

show abstract

“…The PLM images of microparts revealed a typical skin‐core morphology, which was characterized by the presence of a series of distinct regions, namely, the skin layer, interlayer, and core layer. Specifically, the shear layer was composed of a highly oriented structure, which could be parallel lamellar stacks or shish‐kebabs as reported in literature . The core layer contained randomly larger α ‐spherulites without preferred orientation.…”

Section: Resultsmentioning

confidence: 83%

Role of dicumyl peroxide on the morphology and mechanical performance of polypropylene random copolymer in microinjection molding

Yang

Kong

et al. 2017

Polymers for Advanced Techs

View full text Add to dashboard Cite

The purpose of this work is to systematically investigate the effects of dicumyl peroxide (DCP) on the microstructural evolution and mechanical properties of polypropylene random copolymers (PPRs) during the microinjection process. Polarized light microscopy, differential scanning calorimetry, X-ray diffraction, and scanning electronic microscopy measurements were employed to characterize the morphology evolution of the PPR microparts with DCP. A hierarchical structure was found in the PPR microparts with DCP. Specifically, with the individual addition of organic peroxide, the orientation parameter of the PPR microparts decreased pronouncedly and the formation of skin layer was suppressed, while the formation of core layer was promoted.This was ascribed to the distribution of shear rate in the microchannel, which was determined by the wall ship effect in the filling stage and the relaxation behavior in the cooling stage. A mechanism was proposed to explain the distinctive filling behavior and molding characteristics of PPR with DCP in microinjection molding. Microinjection molding possesses many advantages, such as high precision, low cost, and high productivity. Therefore, many microsystem technology-related products, such as micropumps, microgears, optical grating elements, and microheat exchangers, are widely used in many industrial fields. 2,3 During μIM, the interfacial effects of wall slip and surface tension become more pronounced as compared with that of conventional injection molding (CIM). 4The μIM of polymers requires extremely high injection velocity, high mold temperature, and high melt temperature to prevent premature freezing or the occurrence of short shots. Therefore, under such a stringent condition, high shear stress is inevitably produced in the micromold cavities. 5 When the wall shear stress exceeds the critical stress (σ c1 ), the melts slip over the solid surfaces of the microchannel upon which the phenomenon of wall slip occurs. 2The resulting interfacial effects on the morphology and properties of polymers in μIM have since attracted the intense attention of many researchers.Crystalline polymers in microchannels, such as polypropylene, exhibit hierarchical structures and mechanical properties that are strongly dependent on the temperature, velocity profile, and shear stress during the μIM. Chains subjected to a higher shear rate and higher shear stress generally induce the formation of either highly oriented or parallel lamellar stack structures. 6,7 On the contrary, chains with lower shear rates and lower shear stresses induce the formation of a spherulitic structure. The distribution of oriented structures greatly influences the hierarchical Until now, the application of polypropylene resins in microinjection production is limited due to the extremely severe molding condition. A "controlled-rheology polypropylene" technology provides an approach to improve the processing ability of polypropylene resin in μIM, which is performed using a peroxide-initiated scission (β-scission) reactio...

show abstract

Shish–kebab-like cylindrulite structures resulted from periodical shear-induced crystallization of isotactic polypropylene

Cited by 59 publications

References 43 publications

Quantification of the Effect of Shish-Kebab Structure on the Mechanical Properties of Polypropylene Samples by Controlling Shear Layer Thickness

Quantification of the Effect of Shish-Kebab Structure on the Mechanical Properties of Polypropylene Samples by Controlling Shear Layer Thickness

Hierarchic structure and mechanical property of glass fiber reinforced isotactic polypropylene composites molded by multiflow vibration injection molding

Role of dicumyl peroxide on the morphology and mechanical performance of polypropylene random copolymer in microinjection molding

Contact Info

Product

Resources

About