scholarly journals Bionanocomposite Blown Films: Insights on the Rheological and Mechanical Behavior

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1167
Author(s):  
Maria Chiara Mistretta ◽  
Luigi Botta ◽  
Rossella Arrigo ◽  
Francesco Leto ◽  
Giulio Malucelli ◽  
...  
Keyword(s):  
Mechanical Behavior ◽  
Viscoelastic Behavior ◽  
Elongational Flow ◽  
Marginal Effect ◽  
Film Blowing ◽  
Rheological Characterization ◽  
Polyethylene Matrix ◽  
Blown Films ◽  
Twin Screw ◽  
Industrial Level

In this work, bionanocomposites based on two different types of biopolymers belonging to the MaterBi® family and containing two kinds of modified nanoclays were compounded in a twin-screw extruder and then subjected to a film blowing process, aiming at obtaining sustainable films potentially suitable for packaging applications. The preliminary characterization of the extruded bionanocomposites allowed establishing some correlations between the obtained morphology and the material rheological and mechanical behavior. More specifically, the morphological analysis showed that, regardless of the type of biopolymeric matrix, a homogeneous nanofiller dispersion was achieved; furthermore, the established biopolymer/nanofiller interactions caused a restrain of the dynamics of the biopolymer chains, thus inducing a significant modification of the material rheological response, which involves the appearance of an apparent yield stress and the amplification of the elastic feature of the viscoelastic behavior. Besides, the rheological characterization under non-isothermal elongational flow revealed a marginal effect of the embedded nanofillers on the biopolymers behavior, thus indicating their suitability for film blowing processing. Additionally, the processing behavior of the bionanocomposites was evaluated and compared to that of similar systems based on a low-density polyethylene matrix: this way, it was possible to identify the most suitable materials for film blowing operations. Finally, the assessment of the mechanical properties of the produced blown films documented the potential exploitation of the selected materials for packaging applications, also at an industrial level.

Tubular Film Blowing

2006 ◽  
Author(s):  
Chang Dae Han
Keyword(s):  
Elongational Flow ◽  
Fiber Spinning ◽  
Point Of View ◽  
Low Density Polyethylene ◽  
Low Density ◽  
Film Blowing ◽  
Chain Branching ◽  
Blown Films ◽  
Long Chain Branching ◽  
Long Chain

Tubular film blowing has long been used to produce biaxially oriented films using such thermoplastic polymers as low-density polyethylene (LDPE), high-density polyethylene (HDPE), and polypropylene (PP). Here, LDPE refers to a polymer that is synthesized by free-radical polymerization under high pressure (Fawcett et al. 1937). The discovery of linear low-density polyethylene (LLDPE) in the 1980s via the Unipol process (Beret et al. 1986; Jones et al. 1985), which uses a low-pressure gas-phase process, has led to additions to the family of tubular blown films during the past two decades. The discovery of metallocene catalysts (Stevens and Neithamer 1991; Welborn and Ewen 1994) in the 1990s further increased the number of LLDPEs that have been used to produce tubular blown films during the last decade. To distinguish LLDPE from LDPE, LLDPE is sometimes referred to as low-pressure low-density polyethylene (LP-LDPE) and LDPE is referred to as high-pressure low-density polyethylene (HP-LDPE) (see Chapter 6 of Volume 1). In this chapter, however, we use the terminologies LDPE and LLDPE. As described in Chapter 6 of Volume 1, LDPE has a high degree of long-chain branching, while LLDPE has short-chain branching with little or no longchain branching. However, the metallocene catalysts apparently allow one to produce LLDPEs having a wide range of side chains, including a certain degree of long-chain branching. The details of the synthetic procedures for producing such a variety of LLDPEs are closely guarded industrial secrets. Biaxially oriented film can be strong and tough in all directions in the plane of the film. As in fiber spinning, the polymer melt exiting from the die flows under a mechanical tension in the direction of flow. However, in the film blowing process, the tube of molten polymer is extended in both the transverse and the axial (machine) directions. Therefore, rheologically speaking, the film blowing process may be treated from the point of view of biaxial elongational flow, whereas the fiber spinning process may be treated from the point of view of uniaxial elongational flow.

scholarly journals Use of Biochar as Filler for Biocomposite Blown Films: Structure-Processing-Properties Relationships

Polymers ◽  
2021 ◽  
Vol 13 (22) ◽  
pp. 3953
Author(s):  
Luigi Botta ◽  
Rosalia Teresi ◽  
Vincenzo Titone ◽  
Giusi Salvaggio ◽  
Francesco Paolo La Mantia ◽  
...  
Keyword(s):  
Tensile Tests ◽  
Film Blowing ◽  
Water Contact ◽  
Blown Films ◽  
Angle Measurements ◽  
Biocomposite Films ◽  
Oxidative Resistance ◽  
Twin Screw ◽  
Mechanical Performances ◽  
Processing Properties

In this work, biocomposite blown films based on poly(butylene adipate-co-terephthalate) (PBAT) as biopolymeric matrix and biochar (BC) as filler were successfully fabricated. The materials were subjected to a film-blowing process after being compounded in a twin-screw extruder. The preliminary investigations conducted on melt-mixed PBAT/BC composites allowed PBAT/BC 5% and PBAT/BC 10% to be identified as the most appropriate formulations to be processed via film blowing. The blown films exhibited mechanical performances adequate for possible application as film for packaging, agricultural, and compost bags. The addition of BC led to an improvement of the elastic modulus, still maintaining high values of deformation. Water contact angle measurements revealed an increase in the hydrophobic behavior of the biocomposite films compared to PBAT. Additionally, accelerated degradative tests monitored by tensile tests and spectroscopic analysis revealed that the filler induced a photo-oxidative resistance on PBAT by delaying the degradation phenomena.

Role of Glycosaminoglycans in the Mechanical Behavior of the Posterior Sclera

2013 ◽  
Author(s):  
Barbara J. Murienne ◽  
C. Thao D. Nguyen
Keyword(s):  
Mechanical Properties ◽  
Mechanical Behavior ◽  
Viscoelastic Behavior ◽  
Ocular Diseases

Changes in sclera mechanical properties have been shown to play an important role in ocular diseases such as glaucoma 1,2,3 and myopia 4,5. In both diseases, those changes in mechanical behavior were observed along with changes in proteoglycan (PG) and associated glycosaminoglycan (GAG) levels, which have been shown to significantly influence the viscoelastic behavior of other tissues 6.

Structure and Mechanical Behavior of Isotactic Polypropylene Composites Filled with Silver Nanoparticles

e-Polymers ◽  
2007 ◽  
Vol 7 (1) ◽  
Author(s):  
Sie Chin Tjong ◽  
Suping Bao
Keyword(s):  
Mechanical Behavior ◽  
Isotactic Polypropylene ◽  
Ag Nanoparticles ◽  
Screw Extruder ◽  
Additional Increase ◽  
Polypropylene Composites ◽  
Melt Compounding ◽  
Twin Screw ◽  
Izod Impact ◽  
The Impact

AbstractIsotactic polypropylene (PP) nanocomposites containing 0.1, 0.3, 0.5 and 1.0 wt % silver (Ag) nanoparticles were prepared via melt compounding in a twin-screw extruder followed by injection molding The effects of the Ag nanoparticle additions on the structure and mechanical behavior of PP were studied using DSC, WXRD, optical microscopy, tensile and Izod impact techniques. DSC and WXRD measurements showed that the addition of only 0.1 wt% Ag nanoparticles promote the formation of β-form PP. Further increasing Ag content would not lead to additional increase of the β-PP phase content. The induced β- form PP phase is beneficial to enhance the impact strength and tensile ductility of the PP/Ag nanocomposites.

Targeted Loss of Proteoglycans Results in Changes of Frequency-Dependent Viscoelastic Behavior of the Intact Articular Cartilage

2012 ◽  
Author(s):  
Simon Y. Tang ◽  
Tamara Alliston
Keyword(s):  
Articular Cartilage ◽  
Mechanical Behavior ◽  
Viscoelastic Behavior ◽  
Enzymatic Digestion ◽  
Cartilage Tissue ◽  
Indentation Modulus ◽  
Frequency Dependent ◽  
Bovine Articular Cartilage ◽  
Before And After ◽  
Tan Δ

Cartilage is a multi-phasic, viscoelastic material that derives its mechanical behavior of its primary constituents including collagen, proteoglycans, and water. The complex mechanical function of cartilage depends critically on the composition and balance of these constituents. We sought to determine the effects of proteoglycan loss on both the time- and frequency-dependent mechanical behavior of articular cartilage. Using cathepsin d, an enzyme that specifically cleaves proteoglycans, we assessed the in situ mechanical behavior of intact bovine articular cartilage before and after enzymatic digestion using microindentation over loading frequencies ranging between 0.5 hz to 20 hz. The loss of proteoglycans does not affect the elastic components of mechanical behavior (indentation modulus; p = 0.67), but have significant consequences on the viscoelastic components (tan δ; p<0.001). Moreover, the changes in the viscoelastic mechanical behavior are more pronounced at higher loading frequencies (p<0.001). Taken together, these results suggest that proteoglycans are critical for providing dynamic stability for the cartilage tissue.

Multiscale Finite Element Modeling of the Viscoelastic Behavior of Sportswear Under Periodic Load

2020 ◽  
pp. 0887302X2093779
Author(s):  
Ali Sajjadi ◽  
Seyed Abdolkarim Hosseini ◽  
Saeed Ajeli ◽  
Mohammad Mashayekhi
Keyword(s):  
Finite Element ◽  
Mechanical Behavior ◽  
Viscoelastic Properties ◽  
Viscoelastic Behavior ◽  
Tensile Load ◽  
Periodic Load ◽  
Unit Cells ◽  
Multiscale Finite Element ◽  
Optimum Sample ◽  
Good Agreement

The aim of this study was to investigate the influence of different stitch factors on the mechanical behavior of the seam section of sportswear under periodic load. Multiscale finite element (FE) modeling was then utilized to predict the mechanical behavior of the samples under periodic tensile load. The unit cells of the fabric and the stitched section were modeled in the mesoscale. Elastic and viscoelastic properties of the yarns were assigned to the model. In order to obtain the mechanical properties of the sample, periodic boundary conditions were applied to the unit cell. Elastic and viscoelastic properties calculated from the mesoscale were then used for the macromodel. FE results had a good agreement with the experimental ones in predicting the mechanical behavior of the seam section under the periodic tensile load. By using Taguchi method, the optimum sample was found.

scholarly journals Super-Toughed PLA Blown Film with Enhanced Gas Barrier Property Available for Packaging and Agricultural Applications

Materials ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1663 ◽  
Author(s):  
Yuanping Jiang ◽  
Cong Yan ◽  
Kai Wang ◽  
Dawei Shi ◽  
Zhengying Liu ◽  
...  
Keyword(s):  
Viscoelastic Behavior ◽  
Barrier Properties ◽  
Light Transmittance ◽  
Film Material ◽  
Film Blowing ◽  
Gas Barrier ◽  
Melt Strength ◽  
Agricultural Applications ◽  
Green Packaging ◽  
Gas Barrier Properties

Polylactic acid (PLA) holds enormous potential as an alternative to the ubiquitous petroleum-based plastics to be used in packaging film and agricultural film. However, the poor viscoelastic behavior and its extremely low melt strength means it fails to meet the requirements in film blowing processing, which is the most efficient film processing method with the lowest costs. Also, the PLA’s brittleness and insufficient gas barrier properties also seriously limit PLA’s potential application as a common film material. Herein, special stereocomplex (SC) networks were introduced to improve the melt strength and film blowing stability of PLA; polyethylene glycol (PEG) was introduced to improve PLA’s toughness and gas barrier properties. Compared with neat poly(l-lactide) acid (PLLA), modified PLA is stable in the film blowing process and its film elongation at break increases more than 18 times and reaches over 250%, and its O2 permeability coefficient decreased by 61%. The resulting film material also has good light transmittance, which has great potential for green packaging applications, such as disposable packaging and agricultural films.

scholarly journals Rheological characterization of polymer-based nanocomposites with different nanoscale dispersions

e-Polymers ◽  
2005 ◽  
Vol 5 (1) ◽  
Author(s):  
Dong Gi Seong ◽  
Tae Jin Kang ◽  
Jae Ryoun Youn
Keyword(s):  
Storage Modulus ◽  
Extensional Flow ◽  
Rheological Behaviour ◽  
Polyamide 6 ◽  
Twin Screw Extrusion ◽  
Rheological Characterization ◽  
Melt Compounding ◽  
Transmission Electron ◽  
Screw Extrusion ◽  
Twin Screw

AbstractPolyamide 6 - clay nanocomposites with different nanoscale dispersions were prepared by melt compounding via twin-screw extrusion and their internal structures were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The rheological behaviour of these nanocomposites in shear and extensional flow were investigated using an Advanced Rheometric Expansion System and an Elongational Melts Rheometer in connection with the analysis by XRD and TEM. Nanocomposites with fully exfoliated structure and with poorly dispersed structure showed very different rheological behaviour. In general, addition of clay increased the viscosity and the storage modulus of nanocomposites, but different rheological behaviours were observed depending upon the degree of clay dispersion in the polymer matrix. In shear flow, only the exfoliated nanocomposite showed solid-like plateau behaviour in storage modulus and strong shear-thinning behaviour in shear viscosity. In extensional flow, only fully exfoliated nanocomposites showed strain-hardening behaviour, which is caused by the interaction between nanoparticles as well as between polymer molecules and nanoparticles.

Fabrication and Characterization of Polypropylene/Ethylene-Octene Copolymer Blend Nanocomposites

2007 ◽  
Vol 29-30 ◽  
pp. 267-270 ◽  
Author(s):  
S.K. Samal ◽  
S. Mohanty ◽  
S.K. Nayak
Keyword(s):  
Loss Modulus ◽  
Clay Content ◽  
Xrd Analysis ◽  
X Ray Diffraction ◽  
Rheological Characterization ◽  
Maximum Increase ◽  
Cloisite 30B ◽  
Twin Screw ◽  
The Impact ◽  
Blend Nanocomposites

PP/EOC thermoplastic blend nanocomposites were prepared by melt intercalation technique using an intermeshing co-rotating twin screw extruder. The organoclay (Na+ MMT, Cloisite 20A, Cloisite 30B) content was varied between 0-5wt. % whereas the blend composition was kept constant (70PP: 30EOC) as optimized in our previous work. The effects of clays on the mechanical and rheological properties have been studied. Mechanical studies of PP/EOC nanocomposites reveal a significant increase in the impact strength upto a clay content of 3%. X-ray diffraction (XRD) analysis showed a significant increase in the interlayer gallery space with increase in clay loading. The rheological characterization made employing parallel plate rheometer revealed a maximum increase in storage modulus (G’) and loss modulus (G”) in case of modified clay indicating higher stiffness of the nanocomposites as compared to unmodified nanocomposites. Time Temperature superposition (TTS) was employed to generate various viscoelastic mastercurves.

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