Determination of plateau moduli and entanglement molecular weights of ultra-high molecular weight isotactic polypropylene synthesized by Ziegler-Natta catalyst

Niu, Hui; Wang, Yuanjie; Liu, Xiaoyan; Wang, Yanshai; Li, Yang

doi:10.1016/j.polymertesting.2017.04.007

Cited by 20 publications

(11 citation statements)

References 20 publications

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“…Table 10 shows the plateau moduli, as well as the molecular weights between entanglements calculated from Equation (11) for each sample. Notice from Table 10 that the value of M e obtained for the raw PP is almost the same reported in the literature for isotactic PP, which is approximately 6900 g/mol [ 25 , 26 , 27 ]. From the data obtained, it is observed that M e is mainly driven by the M w , in other words, as the molecular chains become shorter, they tend to entangle less.…”

Section: Resultssupporting

confidence: 78%

Investigation of the Mechanical Properties of Parts Fabricated with Ultrasonic Micro Injection Molding Process Using Polypropylene Recycled Material

et al. 2020

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This research focuses on investigating how physical and mechanical properties of polypropylene (PP) recycled material are modified when ultrasonic micro injection molding (UMIM) technology is used to produce material specimens. Experimental characterization by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) spectra, and rheology tests show that the fabricated PP samples were able to withstand up to five times recycled processing before some signs of mechanical and physical properties degradation are observed. Surprisingly, uniaxial extension tests show an increase of 3.07%, 10.97% and 27.33% for Young’s modulus, yield stress and ultimate stress values, respectively, and a slight reduction of 1.29% for the samples elongation at break when compared to the experimental data collected from virgin material samples. The improvement of these mechanical properties in the recycled samples suggests that ultrasonic microinjection produces a mechano-chemical material change.

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Section: Resultssupporting

confidence: 78%

Investigation of the Mechanical Properties of Parts Fabricated with Ultrasonic Micro Injection Molding Process Using Polypropylene Recycled Material

et al. 2020

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“…erefore, no elastic modulus values could be obtained in this area. e plateau region of the elastic modulus was associated with the rubbery behavior of different colloids [46,47]. Across all the emulsions of this study, the values of the elastic modulus whenever a plateau region was found were always higher than the viscous modulus at the same frequencies, which yields information on the elastic nature of the system (the complete information of the viscous and elastic moduli is given in Figures S1-S5).…”

Section: Emulsion Characterizationmentioning

confidence: 58%

A Multiscale Approach to the Design and Manipulation of Oil-in-Water Emulsion-Based Products

Gomez

Pradilla

Álvarez

2021

International Journal of Chemical Engineering

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Advances in computational technology and high-throughput modeling software have given rise to the tailored design of products that require accurate mathematical relationships for their assessment. Industrial emulsion-based products, ubiquitous to everyday life, are complex systems driven by interfacial phenomena that require quick property-prediction tools for their commercialization. In this work, by means of a multiscale approach, mathematical relationships to model oil-in-water emulsions and that can be applied to any commercial emulsion-based product are proposed. The energy consumption during the emulsification process ( E v , which transitions from monotonic increase to exponential growth at 80% w / w ), a parameter responsible for finished product performance, was linked to final product properties at three different levels: (i) molecular, through the dynamics of the interdroplet interactions given their distribution and structure at a microscopic level; (ii) microscopic, through average droplet size yielding an inversely proportional exponential relationship ( D 4,3 ∝ E v − 4 ); and (iii) macroscopic, through the plateau value of the elastic modulus and the flow behavior index leading to inversely proportional quadratic relationships ( G ′ ∝ E v − 2 and η ∝ E v − 2 , respectively). These relationships are valid at dispersed phase concentrations beyond the 60% w / w threshold where the packing of the droplets changes the emulsion’s microscopic structure giving rise to Van der Waals forces-driven phenomena. Finding this threshold allowed expanding the concentration ranges of previously reported models. The main expectation is that these results will aid researchers and process/product designers to optimize their work in different industrial applications.

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“…This is due to the presence of molybdenum disulfide nanoparticles in catalyst support. Adding nanoparticles to polymer matrix, during the polymerization process, prevents the chain growth; therefore, from a certain limit, the growth of the chains stops and the molecular weight reduces comparing to pure polymer …”

Section: Resultsmentioning

confidence: 99%

Effect of exfoliated molybdenum disulfide oxide on friction and wear properties of ultra high molecular weight polyethylene

Amini

Ramazani

Varjouy

et al. 2018

Polymers for Advanced Techs

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The aim of this work is to investigate the effect of molybdenum disulfide on tribological properties of Ultra-high-molecular-weight polyethylene (UHMWPE). UHMWPE/ MoS 2 nano-composites were prepared using in-situ polymerization and Ziegler-Natta catalytic system. Studies showed that, in order to obtain the optimum tribological properties, interlayer distance between nanosheets should be as high as possible.Therefore, the nanosheets were subjected to oxidation using the required oxidants followed by thermal shock and ultrasound. Fourier-transform infrared spectroscopy (FTIR) analysis was used to determine the formation of functional groups which indicate the formation of S═O bond in the molybdenum disulfide oxide. Then, in order to exfoliate and increase the interlayer distance of nanosheets, thermal shock and ultrasonic were conducted Field Emission Scanning Electron Microscopy (FESEM) analyses. Finally, the obtained sample was used as the second support of catalyst in in-situ polymerization process. Then, under specified and constant operational conditions, the synthesis of samples containing 0.5%, 1%, and 2% nanoparticles were conducted. The results of the morphological study with FESEM indicate that the filler is uniformly distributed in the matrix, and X-ray Powder Diffraction (XRD) analysis showed that completely exfoliated nanocomposites were resulted and in low nanoparticle content. Addition of MoS 2 as reinforcing agent had a significant effect on friction coefficient of the nanocomposites. With the addition of 0.5 wt% of MoS 2 , the friction coefficient declined by approximately 35%. Furthermore, negligible decrease in sample's weight after the wear test is an indication of a strong interaction between MoS 2 and the matrix. Scratch resistance test revealed that with the addition of filler, the resistance increased from 23 to 60 MPa.

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Determination of plateau moduli and entanglement molecular weights of ultra-high molecular weight isotactic polypropylene synthesized by Ziegler-Natta catalyst

Cited by 20 publications

References 20 publications

Investigation of the Mechanical Properties of Parts Fabricated with Ultrasonic Micro Injection Molding Process Using Polypropylene Recycled Material

Investigation of the Mechanical Properties of Parts Fabricated with Ultrasonic Micro Injection Molding Process Using Polypropylene Recycled Material

A Multiscale Approach to the Design and Manipulation of Oil-in-Water Emulsion-Based Products

Effect of exfoliated molybdenum disulfide oxide on friction and wear properties of ultra high molecular weight polyethylene

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