Structure and properties of ultrahigh molecular weight polyethylene processed under a consecutive elongational flow

Cao, Changlin; Chen, Xiaochuan; Wang, Junxia; Lin, Yu; Guo, Yiyou; Qian, Qingrong; Chen, Qinghua; Feng, Yi; Yu, Dingshan; Chen, Xudong

doi:10.1007/s10965-017-1422-1

Cited by 17 publications

(20 citation statements)

References 34 publications

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“…The determination of molecular weight is used to evaluate the degree of scission of long molecular chains, especially applied in UHMWPE and its blends due to its ultra‐long molecular chains . M η of samples calculated by the theoretical equation or determined by intrinsic viscosity method is presented in Table , which shows that the determined M η ( M η D ) was slightly lower than the theoretical M η ( M η T ), which indicated that few chain scissions occurred in the mixing process.…”

Section: Resultsmentioning

confidence: 99%

“…In the work reported here, an innovative eccentric rotor extruder (ERE), which generated elongational flow in the whole conveying, mixing and plasticizing process, was found to give good dispersal and led to a shorter processing time than a twin‐screw extruder (TSE) . Especially, compared to shear flow, the elongational flow well retained the intrinsic molecular weight of neat UHMWPE that indicated very little chain scission . Therefore, the novel device was employed to melt‐blend HDPE/UHMWPE mixtures and improve the dispersion of UHMWPE in the HDPE matrix, which can provide a more continuous, simple and economical approach and short processing time to mix HDPE/UHMWPE blends without pronounced chain scission.…”

Section: Introductionmentioning

confidence: 99%

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Short‐time fabrication of well‐mixed high‐density polyethylene/ultrahigh‐molecular‐weight polyethylene blends under elongational flow: morphology, mechanical properties and mechanism

Lin

Yang

2019

Polymer International

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As linear polyethylenes, ultrahigh‐molecular‐weight polyethylene (UHMWPE) and high‐density polyethylene (HDPE) have the same molecular structure, but the large difference in viscosity between them makes it difficult to obtain well‐mixed blends. An innovative eccentric rotor extruder (ERE) generating an elongational flow was used to prepare HDPE/UHMWPE blends within short processing times. Compared with the obvious two‐phase morphology of a sample from a twin‐screw extruder observed with a scanning electron microscope, few small UHMWPE particles were observed in the HDPE matrix for a sample from the ERE, indicating the good mixing on a molecular level of HDPE/UHMWPE blends achieved by the ERE during short processing times. The morphological changes of blends prepared using the ERE evidenced the good integration of HDPE and UHMWPE even though the UHMWPE content is up to 50 wt% in the blends. Moreover, all blends retained most of the intrinsic molecular weight. The good mixing was further confirmed from the thermal, crystallization and rheological behaviors determined using differential scanning calorimetry and dynamic rheological measurements. Importantly, the 50/50 blend presented improved mechanical properties, especially super‐impact strength of 151.9 kJ m−2 with incomplete‐break fracture state. The strengthening and great toughening effects of UHMWPE on the blends were attributed to the addition of unwrapped UHMWPE long molecular chains. The effective disentanglement mechanism of UHMWPE chains under elongational flow was explained schematically by a non‐parallel three‐plate model. © 2019 Society of Chemical Industry

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Short‐time fabrication of well‐mixed high‐density polyethylene/ultrahigh‐molecular‐weight polyethylene blends under elongational flow: morphology, mechanical properties and mechanism

Lin

Yang

2019

Polymer International

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“…For the electrical performance of all nanocomposites, it is not difficult to understand why the conductivity of the ISBS x% nanocomposites has a similar inverted S‐shaped trend as the OBSH loading further increases. Overall, extensive research about the elongation rheology suggests that the dynamic elongation deformation field is more effective at the dispersion of nanoparticles in a short thermal‐mechanical history than shear flow field . Owing to the convergent and divergent flow in the vane mixer, the bubbles are endowed with the special capacity of repeated compression and expansion.…”

Section: Resultsmentioning

confidence: 99%

Homogeneous dispersion of multiwalled carbon nanotubes via in situ bubble stretching and synergistic cyclic volume stretching for conductive LDPE/MWCNTs nanocomposites

Yang

Tong

et al. 2019

Polymer Engineering & Sci

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Low-density polyethylene (LDPE)/multiwalled carbon nanotubes (MWCNTs) nanocomposites with different foaming agent (OBSH) contents were innovatively prepared via In Situ Bubble Stretching (ISBS) and synergistic cyclic volume stretching. The cyclic convergent and divergent flow makes the MWCNTs repeatedly subjected to bubble stretching, which is conducive to the efficient dispersion of MWCNTs in the matrix. The thermal weight loss of neat OBSH and nanocomposite were characterized by thermal gravimetric analyzer (TGA), which indicated that the OBSH in the nanocomposite had been completely decomposed into gas during the plasticizing transport process. The results of morphology showed that the moderate content of OBSH had better dispersion effect on MWCNTs. At optimal OBSH content, the OBSH could generate enough gas and larger bubbles per unit time to provide greater expansion forces to do much for the dispersion of MWCNTs. The dynamic mechanical analysis (DMA) was further carried out and also proved that the content of OSBH was an important factor for the dispersion of MWCNTs. Moreover, the relationship between the OBSH content and conductivity was discussed in details. The improvement in conductive properties of nanocomposites associated with the use of the method can be attributed to a more homogeneous dispersion of MWCNTs. POLYM. ENG.

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“…When the synergy angle α becomes zero, the flow is a pure elongational one, and if it becomes 90°, the flow is a pure shear one. Most notably, it is generally known that the effect of elongational flow on mixing is more strong than that of shear flow [19][20][21][22][23][24], which provides evidence for the feasibility of field synergy analysis. Therefore, the synergy relationship provides a new perspective to understand the polymer mixing.…”

Section: Synergy Between Velocity and Velocity Gradientmentioning

confidence: 99%

Multi-Field Synergy Process for Polymer Plasticization: A Novel Design Concept for Screw to Facilitate Phase-to-Phase Thermal and Molecular Mobility

Jian¹,

Chen²,

Yang³

2020

Thermosoftening Plastics

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A novel concept of screw design has been proposed considering the multi-field synergy principle to facilitate phase-to-phase thermal and molecular mobility; subsequently, a torsion element has been designed. This new screw design allows an innovative and effective way to resolve a growing challenge in polymer process engineering, especially for nanocomposites or biopolymers, that is, an inadequate control of mass transfer and thermal management for multicomponent melt flows through narrow channels during extrusion or injection. The adaption of torsion element in the screw facilitated the plasticization mixing and thermal distribution in polymer melts, and the torsional flow induced by the torsion elements shows a synergistic effect on the melt-phase mass flow and the thermal flow field. The latter effect enhances the mass and heat transfer of heterogeneous polymer systems and realizes effective heat management to achieve properly uniform temperature field.

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Structure and properties of ultrahigh molecular weight polyethylene processed under a consecutive elongational flow

Cited by 17 publications

References 34 publications

Short‐time fabrication of well‐mixed high‐density polyethylene/ultrahigh‐molecular‐weight polyethylene blends under elongational flow: morphology, mechanical properties and mechanism

Short‐time fabrication of well‐mixed high‐density polyethylene/ultrahigh‐molecular‐weight polyethylene blends under elongational flow: morphology, mechanical properties and mechanism

Homogeneous dispersion of multiwalled carbon nanotubes via in situ bubble stretching and synergistic cyclic volume stretching for conductive LDPE/MWCNTs nanocomposites

Multi-Field Synergy Process for Polymer Plasticization: A Novel Design Concept for Screw to Facilitate Phase-to-Phase Thermal and Molecular Mobility

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