Role of Rheology in Melt Processing

Dealy, John M.; Wang, Jian

doi:10.1007/978-94-007-6395-1_8

Cited by 6 publications

(12 citation statements)

References 59 publications

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“…The value of η 0 of PP and PPgV are consistent with a decrease of about three times in weight average molecular weight of PP when considering the relation η 0 $ M w 3.4 applicable to linear simple polymers. 40 This result is in agreement with previous ones, when low concentration of MA has been grafted to the same PP also using DBPH. 36 The dynamic moduli of N2V, N5V, and N10V appearing in Figure 7 fall in between those of PP and PPgV.…”

Section: Rheological Characterizationsupporting

confidence: 93%

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Polypropylene nanocomposites produced by in‐situ grafting of maleic anhydride using different mixing procedures

Merchán Sandoval,

Failla,

Quinzani

2024

Polymer Composites

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Nanocomposites (NC) of polypropylene (PP) and organophilic montmorillonite (oMt) are produced by reactive mixing with simultaneous grafting of maleic anhydride (MA) onto PP using organic peroxide as initiator. Five different strategies of incorporating reactants and clay into a laboratory mixer are used. The structure of composites is examined by FT‐IR spectroscopy, x‐ray diffraction and scanning electron microscopy. Rotational rheometry, thermogravimetry and oxygen permeability are used to evaluate properties. The preparation method has a remarkable influence on NC's structure. Simultaneous addition of peroxide and MA to molten PP followed by incorporation of clay 20 minutes later produces the best degree of clay exfoliation/disaggregation. The NCs obtained using this procedure are highly transparent and have very thin tactoids with interlayer spacing more than 50% larger than the original oMt. The incorporation of just 2 wt% of clay gives place to more than 30% reduction in PP oxygen permeability. Additionally, the temperature at the maximum thermal degradation rate in nitrogen reduces in about 60°C while the temperature at which the thermal degradation process begins is not affected.Highlights Highly intercalated/exfoliated PP/oMt nanocomposites are synthesized Reactive mixing procedure affects the quality of nanocomposite's structure A initial period of grafting before clay addition is the most effective method Highly transparent materials with small tactoids of d001>4 nm is generated PP oxygen permeability is highly reduced by the use of just 2 wt% of nanoclay

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Section: Rheological Characterizationsupporting

confidence: 93%

“…In case of PP, this value was estimated by fitting the viscosity data to the Carreau-Yasuda model. 40 Additionally, the terminal relaxation time, λ 0 , calculated from the dynamic moduli at small frequencies as λ 0 ¼ lim…”

Section: Structural Characterizationmentioning

confidence: 99%

Polypropylene nanocomposites produced by in‐situ grafting of maleic anhydride using different mixing procedures

Merchán Sandoval,

Failla,

Quinzani

2024

Polymer Composites

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“…It is possible that the lubricating water layer or the depletion layer that forms between two phase materials and solid surfaces suppressed the stick-slip behavior common in capillary dies. 49,50 On the other hand, a small amount of die swell was observed as the extrudates were on average slightly thicker (1.46 ± 0.05 mm) than the set die gap width (1.13 mm). When compared against laboratory processing techniques (e.g., solution casting), the major benefit that comes from using the proposed methodology (a shear mixer to produce pastes and an extruder to continuously process sheets) is the significant reduction in processing time.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…It is also important to point out that at all the screw speeds, there was neither a “shark skin” nor a ridged pattern observed at the extrudate’s surface. It is possible that the lubricating water layer or the depletion layer that forms between two phase materials and solid surfaces suppressed the stick-slip behavior common in capillary dies. , On the other hand, a small amount of die swell was observed as the extrudates were on average slightly thicker (1.46 ± 0.05 mm) than the set die gap width (1.13 mm).…”

Section: Resultsmentioning

confidence: 99%

Continuous Processing of Cellulose Nanofibril Sheets Through Conventional Single-Screw Extrusion

Azrak

Costakis

Moon

et al. 2020

ACS Appl. Polym. Mater.

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Extrusion-based processes are one of the most widely used continuous polymer processing techniques because of their commercial availability, versatility, and cost-effective scalability. For these reasons, conventional single-screw extrusion was investigated and used for continuously processing mechanically fibrillated cellulose nanofibrils (CNFs) into wet sheets. A high shear mixing procedure was used to process highly loaded CNF pastes with up to ∼25 wt % solids, composed of ∼91 wt % CNF and ≤ ∼9 wt % of a processing aid like carboxymethyl cellulose (CMC), xanthan gum (XG), or anionic polyacrylamide (aPAM). Validation of the mixing procedure proved that highly loaded CNF/processing aid pastes can be processed in under 40 min. The higher solid loadings significantly reduced the preparation and drying time. The water-retention ability and stability of CNF suspensions containing different processing aids were assessed through centrifugation and zeta potential analysis. Extrusion of the prepared pastes showed that cohesive sheets could be produced continuously at output rates of 7.45 ± 0.47 kg/h (or 1.14 ± 0.072 dry) without the introduction of surface defects. Wet extrudates with an average width of ∼5 cm and thickness of 1.46 ± 0.05 mm were continuously processed, with the length limited only by the lack of collection rolls. A viscosity−shear rate dependence analysis linked extrudate homogeneity and reduced defects to a stronger Newtonian response for CNF/CMC pastes when compared to pure CNFs. On the other hand, CNF/XG and CNF/aPAM pastes experienced a much stronger shear thinning response, which correlated with a stronger appearance of observable aggregates and pinhole defects in the extrudates. Tensile testing of the pressed and heated CNF/CMC extrudates revealed equivalent mechanical properties to cast CNF films prepared through conventional solution casting. Lastly, preliminary calendering results for CNF/CMC extrudates showed that full consolidation can be achieved, thus providing a way to continuously dry and press the wet extrudates.

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“…The Cole–Cole distribution reveals a significant increase in zero-shear viscosity by adding argan byproduct as a filler, especially in the case of argan shell, as shown in the results. The increased effect of viscosity after the addition of the filler is normally due to the restricted mobility of chain segments, which alters the normal polymer flow [ 57 , 58 ]. In addition, the good distribution and good affinity of rigid bio-filler into the polymer increases its resistance to flow and subsequently results in an increase in viscosity [ 59 , 60 ].…”

Section: Resultsmentioning

confidence: 99%

Thermal, Morphological and Mechanical Properties of a BioPE Matrix Composite: Case of Shell, Pulp, and Argan Cake as Biofillers

et al. 2023

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Extrusion and hot compressing molding processes were used to create bio-polyethylene (BioPE) composites reinforced with argan byproducts (shell, pulp, and argan cake) as bio-fillers. The thermal stability of the composites wass analyzed by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Dynamical mechanical analysis and rheological testing were used to investigate their mechanical properties. The morphological results showed a good adhesion between the argan and BioPE matrix. More efficient mechanical properties have been distinguished in the case of argan byproduct-based composite. A higher Young’s modulus was noted for all the biocomposites compared to pure BioPE. Thermal analysis revealed that the addition of bio-filler to polymer reduced decomposition temperatures. This study provides an ecological alternative for upgrading the valorization of abundant and underutilized Moroccan biomass. Furthermore, the possibility of using argan byproducts in composite manufacturing will help open up new markets for what is currently considered waste.

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Role of Rheology in Melt Processing

Cited by 6 publications

References 59 publications

Polypropylene nanocomposites produced by in‐situ grafting of maleic anhydride using different mixing procedures

Polypropylene nanocomposites produced by in‐situ grafting of maleic anhydride using different mixing procedures

Continuous Processing of Cellulose Nanofibril Sheets Through Conventional Single-Screw Extrusion

Thermal, Morphological and Mechanical Properties of a BioPE Matrix Composite: Case of Shell, Pulp, and Argan Cake as Biofillers

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