Caracterização viscosimétrica de nanocompósitos híbridos PS/POSS

Bianchi, Otávio; Repenning, Gustavo Borcelli; Mauler, Raquel Santos; Oliveira, Ricardo Vinícius Bof de; Canto, Leonardo Bresciani

doi:10.1590/s0104-14282012005000022

Cited by 10 publications

(13 citation statements)

References 46 publications

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“…In the case of acrylic fiber production viscosity related molecular weight is used as a control method for polymer quality. Although widely used, viscosity is not an absolute method to measure molecular weight, since it depends on other properties, such as temperature, polymer morphology, size and shape of the solvent molecules [21][22][23][24] . Solution viscosity is basically a measure of the size or extension in space of polymer molecules, and is empirically related to molecular weight for linear polymers [2] .…”

Section: Determination Of Intrinsic Viscosity and The Viscometric Molmentioning

confidence: 99%

“…However, several studies reported that at low polymer concentration in the solution, and thus it is diluted, it makes feasible to extrapolate to infinite dilution [2,[21][22][23][24] . According to Etxabarren [23] , in most cases the concentration dependence is not relevant in applications which the polymer concentration tends to a weight or volume fraction close to unity.…”

Section: Intrinsic Viscosity and Viscosity Average Molecular Weight M Vmentioning

confidence: 99%

“…According to Etxabarren [23] , in most cases the concentration dependence is not relevant in applications which the polymer concentration tends to a weight or volume fraction close to unity. In solutions with dilution to infinity, the interactions between the polymer chains disappear and excluded volume effects related to the molecular segments become negligible [24] . Therefore, it is possible to determine the intrinsic viscosity under these considerations.…”

Section: Intrinsic Viscosity and Viscosity Average Molecular Weight M Vmentioning

confidence: 99%

“…From values of intrinsic viscosity, k and α constants, the viscosity average molecular weight M v were obtained by Mark-Houwink-Sakurada relation, shown in Equation 2. The k and α parameters are empirical constants which depends on the temperature and nature of the polymer/solvent interaction [2,21,24] . For example, in monodisperse solutions, which have a single particle size, the constant α equals 1, thus M v =M w .…”

Section: Intrinsic Viscosity and Viscosity Average Molecular Weight M Vmentioning

confidence: 99%

“…For example, in monodisperse solutions, which have a single particle size, the constant α equals 1, thus M v =M w . However, most of the solutions obtained are polydisperse in practice and the constant α can range from 0.5 to 1, and is generally between 0.6 and 0.8 [2,24] . The polyacrylonitrile/DMF solvent/temperature system was used in the present work at 20°C.…”

Section: Intrinsic Viscosity and Viscosity Average Molecular Weight M Vmentioning

confidence: 99%

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Synthesis and Thermal Behavior of Polyacrylonitrile/Vinylidene Chloride Copolymer

et al. 2014

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Polyacrylonitrile fiber encompasses a broad range of products based on acrylonitrile (AN) which is readily copolymerized with a wide range of ethylenic unsaturated monomers giving rise to polymers with different characteristics and applications. Such products can be designed for cost-effective, flame and heat resistant solutions for the textile industry, aircraft and automotive markets. In the present work acrylonitrile was copolymerized with vinylidene chloride (VDC) by conventional suspension polymerization process via redox system, with an initial content of 10%/mass of the VDC monomer. The copolymer average molecular weight was obtained by Gel Permeation Chromatography (GPC) and by intrinsic viscosity analysis. To control the polymerization process continuously, qualitative and quantitative analysis of the chloride content in the PAN AN/VDC copolymer structure was accomplished by using X-ray fluorescence and potentiometric titration techniques. A good correlation was found between these two techniques, leading to a straightforward verification of VDC in the polymer structure. The thermal behavior of PAN AN/VDC copolymer was performed by Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA). The results showed that VDC monomers exhibited a nearly stoichiometric reaction with acrylonitrile, copolymerizing about 90% of its initial mass. VDC changed significantly the polyacrylonitrile thermal behavior, decreasing the polymer degradation temperature by about 40-50°C.

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Section: Determination Of Intrinsic Viscosity and The Viscometric Molmentioning

confidence: 99%

Section: Intrinsic Viscosity and Viscosity Average Molecular Weight M Vmentioning

confidence: 99%

Section: Intrinsic Viscosity and Viscosity Average Molecular Weight M Vmentioning

confidence: 99%

Section: Intrinsic Viscosity and Viscosity Average Molecular Weight M Vmentioning

confidence: 99%

Section: Intrinsic Viscosity and Viscosity Average Molecular Weight M Vmentioning

confidence: 99%

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Synthesis and Thermal Behavior of Polyacrylonitrile/Vinylidene Chloride Copolymer

et al. 2014

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Reactive melt blending of PS‐POSS hybrid nanocomposites

Bianchi

Barbosa

Machado

et al. 2012

J of Applied Polymer Sci

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Hybrid nanocomposites of polystyrene (PS) and methacryl phenyl polyhedral oligomeric silsesquioxane (POSS) were synthesized by reactive melt blending in the mixing chamber of a torque rheometer using dicumyl peroxide (DCP) as a free radical initiator and styrene monomer as a chain transfer agent. The effects of mixing intensity and composition on the molecular structure and morphology of the PS-POSS hybrid nanocomposites were investigated. The degree of POSS hybridization (a POSS ) was found to increase with the POSS content, DCP/POSS ratio, and rotor speed. For the PS-POSS materials processed in the absence of styrene monomer, an increase in the a POSS led to a reduction in the molecular weight by PS chain scission, as a consequence of the free radical initiation. On the other hand, the use of styrene monomer as a chain transfer agent reduces the steric hindrance in the hybridization reaction between POSS and PS, enhancing the degree of POSS hybridization and avoiding PS degradation. The PS-POSS morphology consists of nanoscale POSS clusters and particles and microscale crystalline POSS aggregates. PS-POSS with higher a POSS values and lower amounts of nonbound POSS showed improved POSS dispersion, characterized by smaller interfacial thickness (t) and greater Porod inhomogeneity lengths (l p ). The processing-molecular structure-morphology correlations analyzed in this study allow the POSS dispersion level in the PS-POSS materials to be tuned by controlling the reactive melt blending through the choice of the processing conditions. These insights are very useful for the development of PS-POSS materials with optimized performance.

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Structure and properties relationship of melt reacted polyamide 6/malenized soybean oil

Ernzen

Bondan

Luvison

et al. 2015

J of Applied Polymer Sci

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In this work, a maleinized soybean oil (SOMA) was melt reacted with polyamide 6 and the thermal, rheological, and morphological properties were evaluated. It was observed that the maleinized soybean oil reacted with polyamide chains, increasing the molecular weight of the polymer. Addition of SOMA also promoted an increase in the amount of α crystalline phase as well as in the crystallinity index. The average amorphous layer thickness (La) was enhanced with the addition of 1 wt % of SOMA, while the average crystalline layer thickness (Lc) were significantly enlarged with the increase in SOMA content, indicating that SOMA structures were located at the interfacial region between amorphous and crystalline. The addition of 5 wt % of SOMA plasticized the PA6, reducing its glass transition temperature. However, the sample containing 5 wt % of SOMA showed an accentuated pseudoplastic behavior as compared to other samples. Addition of SOMA also reduced the tensile strength and increased the elongation at break. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43050.

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Caracterização viscosimétrica de nanocompósitos híbridos PS/POSS

Cited by 10 publications

References 46 publications

Synthesis and Thermal Behavior of Polyacrylonitrile/Vinylidene Chloride Copolymer

Synthesis and Thermal Behavior of Polyacrylonitrile/Vinylidene Chloride Copolymer

Reactive melt blending of PS‐POSS hybrid nanocomposites

Structure and properties relationship of melt reacted polyamide 6/malenized soybean oil

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