Table 1 - uploaded by Khalid Lamnawar
Content may be subject to copyright.
Source publication
This study was dedicated to the blown film extrusion of poly(lactic acid), which mainly presents poor shear and elongation viscosities, and its blends. In order to enhance its melt strength, two main routes were selected (i) a structural modification through chain extension and branching mechanisms by adding a reactive multifunctional epoxide (name...
Context in source publication
Similar publications
In this work, poly(lactic acid) (PLA)/cellulose-nanowhisker (CNW) nanocomposites were prepared by twinscrew extrusion followed by injection moulding. The CNW was dispersed in a plasticiser/compatibiliser (PL) before the melt mixing process. It was found that the PL not only improved the processability and reduced the fragility of PLA but also preve...
Citations
... As shown in Fig. 1c, dispersed phase ellipsoids are created due to incorporating 1 wt% chain extender to the optimal 75/25 blend. Deformed drop retraction method (DDRM) improved the surface interfacial [42]. In fact, the blend morphology is skin-core type, with the dispersed phase located in the central point of the film thickness (core region). ...
Efforts to develop and implement an increasing number of biodegradable polymers continue to grow worldwide; nevertheless, substantial obstacles must undoubtedly be surmounted in order to produce biodegradable polymers that exhibit exceptional properties and high performance. With the objective of enhancing the compatibility between the two intrinsically immiscible polymers, polybutylene adipate-co-terephthalate (PBAT) and poly(butylene adipate) (PLA), we employed epoxidized polyhedral oligomeric silsesquioxanes (epoxy-POSS) nanoparticles. A solution-casting method was employed to fabricate nanocomposites comprising a nanoparticle and two biocompatible polymers. This process proved to be highly effective. The distinctive morphology, high strength, toughness, and thermal stability of these nanocomposites were demonstrated by a variety of experiments at 1 wt% nanoparticle. The opposite effect was observed when nanoparticles were added exceeding 1 wt%; consequently, the degree of compatibility between the polymer phases diminished. The impact strength and elongation-at-break of the composite samples were significantly altered at 1% nanoparticle application, going from 57.04 MPa and 520% to about 400% and 62.4 MPa, respectively, as compared to pristine PLA. Microscopic observations showed that the dispersion of nanoparticles in all three phases was dispersed, continuous, and the interface was uniform, and the presence of nanoparticles prevented the melt crystallization of PLA.
... This also influenced the cold crystallization temperature Tcc of PLA, which decreased to 106 • C for the uncompatibilized blend. The PA11 domains acted as nucleation centers, thus improving the crystallization of PLA in the mixtures [25]. ...
... This also influenced the cold crystallization temperature Tcc of PLA, which decreased to 106 °C for the uncompatibilized blend. The PA11 domains acted as nucleation centers, thus improving the crystallization of PLA in the mixtures [25]. ...
The objective of the present study was to investigate multiphase systems based on polylactic acid (PLA) and polyamide 11 (PA11) from blends to multilayers. Firstly, PLA/PA11 blends compatibilized with a multifunctionalized epoxide, Joncryl, were obtained through reactive extrusion, and the thermal, morphological, rheological, and mechanical behaviors of these materials were investigated. The role of Joncryl as a compatibilizer for the PLA/PA11 system was demonstrated by the significant decrease in particle size and interfacial tension as well as by the tensile properties exhibiting a ductile behavior. Based on these findings, we were able to further clarify the effects of interdiffusion and diffuse interphase formation on the structure, rheology, and mechanics of compatible multilayered systems fabricated with forced-assembly multilayer coextrusion. The results presented herein aim to provide a deeper understanding of the interfacial properties, including the rheological, mechanical, and morphological behaviors, towards the control of the interface and confinement in multilayer polymers resulting from coextrusion, and also to permit their use in advanced applications.
... Micic and Bhattacharya 214 have also reported that very high shear viscosity leads to bubble instability. Al-Itry et al. 212 have attributed the high film blowability of Joncryl-modified PLA to the enhancement of both the shear and elongational properties of PLA due to its modification with Joncryl. In their studies on the blown film extrusion of bionanocomposites, Mistretta et al. 215 have stated the importance of appropriate shear viscosity in the achievement of superior film blowability. ...
This review presents fundamental knowledge and recent advances pertaining to research on the role of rheology in polymer processing, highlights the knowledge gap between the function of rheology in various processing operations and the importance of rheology in the development, characterization, and assessment of the morphologies of polymeric materials, and offers ideas for enhancing the processabilities of polymeric materials in advanced processing operations. Rheology plays a crucial role in the morphological evolution of polymer blends and composites, influencing the type of morphology in the case of blends and the quality of dispersion in the cases of both blends and composites. The rheological characteristics of multiphase polymeric materials provide valuable information on the morphologies of these materials, thereby rendering rheology an important tool for morphological assessment. Although rheology extensively affects the processabilities of polymeric materials in all processing operations, this review focuses on the roles of rheology in film blowing, electrospinning, centrifugal jet spinning, and the three-dimensional printing of polymeric materials, which are advanced processing operations that have gained significant research interest. This review offers a comprehensive overview of the fundamentals of morphology development and the aforementioned processing techniques; moreover, it covers all vital aspects related to the tailoring of the rheological characteristics of polymeric materials for achieving superior morphologies and high processabilities of these materials in advanced processing operations. Thus, this article provides a direction for future advancements in polymer processing. Furthermore, the superiority of elongational flow over shear flow in enhancing the quality of dispersion in multiphase polymeric materials and the role of extensional rheology in the advanced processing operations of these materials, which have rarely been discussed in previous reviews, have been critically analyzed in this review. In summary, this article offers new insights into the use of rheology in material and product development during advanced polymer-processing operations.
... The change in complex viscosity is attributed to the PBAT molecular chain entanglement with PBS molecular chain mediated by the transesterification product acting as a compatibilizer [21], which formed pseudo structures to withstand shear forces. Ralltry [25] et al. also reported a similar behavior in PLA/PBAT blends at lower frequencies and considered that the melt viscosity was increased because of the interaction between the polymers. The Cole-Cole plot mainly describes the viscoelastic properties of the blends with a relaxation time distribution, and the plot was shown between imaginary viscosity (η") and real viscosity (η ). ...
The ternary blends of a high content of thermoplastic starch (TPS), poly(butylenes adipate-co-terephthalate) (PBAT), and poly(butylene succinate) (PBS) were first melt-compounded in a twin screw extruder. The TPS contents in ternary blends were fixed at 60 wt%. The miscibility, morphology, thermal behavior, mechanical properties, and thermal resistance of the blends were investigated. The results showed that dispersions of PBS and PBAT minor phases improved the tensile strength and elongation at break. TPS/PBS/PBAT60/10/30 formed a good balance in strength and toughness. Dynamic mechanical analysis of the blends exhibits an intermediate and peak suggesting the ternary blend is compatible. Minor phase-separated structure SEM results showed that TPS/PBS/PBAT60/10/30 blend formed a typical mixture with core-shell morphology. As the PBAT composition was increased, phase morphology changes occurred in the blends, leading to decreased values of complex viscosity, storage modulus, and loss modulus. Moreover, the thermal resistances and melt flow properties of the materials were also studied by analysis of the heat deflection temperature (HDT) and melt flow index (MFI) value in the work.
... Moreover, it exhibits low toxicity, biocompatibility, exceptional durability, and high transparency. Furthermore, it has been observed that, under favorable circumstances, PLA degrades completely [21]. Due to all these advantages, PLA is one of the most commercially used biopolymers and has various applications across several industries. ...
The increasing concern over environmental pollution caused by petroleum-based plastics has resulted in a growing demand for sustainable and eco-friendly alternatives. Polylactic acid (PLA) is a biopolymer that has gained significant attention as a potential replacement for traditional plastics due to its biocompatibility and biodegradability. Nevertheless, PLA needs further research and development due to its lack of physio-chemical aspects. PLA is blended with additives in the form of bio or chemical-based nanofillers (NFs) to improve its physio-chemical, mechanical, thermal, and antibacterial properties. This comprehensive review explores the various types of NFs and their synthesis methods. The various processes employed for blending PLA and NFs are presented. The potential of incorporating NFs with PLA to enhance its properties is also explored. Through a critical analysis of current research, this review aims to evaluate the efficacy of this approach and assess the potential applications of PLA-NF blends in the food processing industry, bone tissue engineering, and skin generation.
... After 10 minutes, the bending angle is 7° and the form recovery rate is 96.5%. The accumulated energy in frozen molecular chains is progressively released, and the thermal motion of molecules in TPI is similarly accelerated [21][22][23][24]. As the weight percentage of CNT grew, the form recovery rates of all specimens decreased. ...
TPI, also known as artificial eucommia rubber, is a thermo-responsive SMP created by molecular recombination and modification with contemporary polymer synthesis and modification techniques. In this paper, TPI shape memory polymer is reinforced with different weight proportions (0, 0.2%, 0.4%, 0.6%, 0.8% and 1%) of carbon nanotube (CNT) and specimens were fabricated with the aim of enhancing the properties of neat TPI polymer composites. Some thermo-mechanical characteristics were investigated and interpreted, including the differential scanning calorimeter (DSC) test, dynamic mechanical analysis (DMA) test, thermal conductivity test, compression test, and a few shape memory properties such as shape recovery ratio and shape recovery rate. TPI shape memory polymers exhibit strong shape memory capabilities and the best mechanical properties based on the testing results for the specimen TPI with 0.8% CNT weight fraction.
... 8a presents the extensional data for PLA V, which are well superposed with the linear viscoelastic envelope (LVE) (3η + 0 (t)) at strain rates of 0.05 and 1 s −1 . This indicates that the Trouton ratio (Tr = η e /η 0 ) is equal to 3, which is the limiting case of Newtonian fluids [62]. As expected, the neat PLA did not exhibit any strain hardening at the strain rates investigated. ...
... The absence of strain hardening for the neat PLA confirms that the polymer is not suitable for blown film processing, for instance. However, at values of 0.1 and 0.5 s −1 , an apparent strain-hardening behavior was observed, i.e., Tr slightly diverged from 3. The occurrence of strain hardening for linear PLA has been reported in some studies and might be related to its stereoregularity [62,64]. In fact, the stereo-regularity of high L-content PLA (96% of L content for PLA 2002D) may allow the formation of a range of structures when stretched [62]. ...
... However, at values of 0.1 and 0.5 s −1 , an apparent strain-hardening behavior was observed, i.e., Tr slightly diverged from 3. The occurrence of strain hardening for linear PLA has been reported in some studies and might be related to its stereoregularity [62,64]. In fact, the stereo-regularity of high L-content PLA (96% of L content for PLA 2002D) may allow the formation of a range of structures when stretched [62]. ...
Agave Tequilana Weber (ATW) is the base ingredient for preparing tequila liquor; tequila production yields tons of waste rich in cellulose representing environmental issues. Cellulose nanocrystals (CNC), the crystalline regions extracted from cellulose microcrystals, were obtained from the waste of ATW as an attractive alternative to reinforce polymeric materials. CNC were grafted with (poly (2-ethyl hexyl acrylate) to improve compatibility with hydrophobic polymers. The CNC pristine (CNCP) and grafted (CNCG) were dispersed in PLA (0.5, 1 and 2 wt.%), employing several melt processing stages. CNC distribution within PLA matrix was followed using SEM and TEM. Also, thermal properties were characterized through differential scanning calorimetry and thermogravimetric analysis. Thermal stability of nanocomposites increased with CNC, CNCG nanocomposites showed better results (Td ~ 370 °C) than CNCP nanocomposites (Td ~ 366 °C). The degree of crystallinity showed for CNCG (25.1%) was higher than for CNCP (21.1%) nanocomposites. The tensile properties were improved with CNCP (0.44 MPa) and CNCG (2.11 MPa) content. The CNC increased the shear properties of PLA melt and exhibited a strain-hardening behavior during elongational rheology test. The CNC and CNCG are an interesting alternative to modify the melt rheological behavior and the mechanical behavior in the solid-state of low melt strength polymers, which could be thermally degraded during processing. Composites could be used to produce films for the food industry through blow-extrusion processing.
Graphical abstract
... [2] Moreover, the incorporation of multifunctional chain extenders in these blends has allowed to further improve the compatibility and therefore the performance of the final manufacture and, at the same time, to improve the processability of the system for the film blowing process. [3,4] Most of the existing literature on PLA/PBAT films is mainly focused on the improvement of their performance. [4][5][6] However, few information is available on the effect of the process DOI: 10.1002/masy.202100251 ...
Poly(lactide) (PLA) and poly(butylene‐adipate‐co‐terephthalate) (PBAT) blends are among the most promising biodegradable materials for flexible packaging applications and the film blowing is one of the most common techniques to make plastic films. In this work, a study on the effect of the cooling air during the production process of blown films made by compatibilized PLA/PBAT blend has been performed. The application of cooling air has led to a significant reduction of the thermal shrinkage of the films in the transverse direction, respect to the machine direction, and has been beneficial in order to improve their mechanical and optical properties.
... On the contrary, previous rheological studies involving PLA dispersions have been limited to highly viscous polymer melts in which the polyester was the matrix and the filler was the dispersed phase, aiming at a particlemodified PLA-based material. 34,35 Here, both the viscosity and the viscoelastic behavior of aqueous PLA/XG dispersions were studied at different compositions, where the concentration of both the dispersed phase and the aqueous XG matrix were independently varied. The time−concentration principle was then applied to cover a wider range of frequencies. ...
In this work, the rheological behavior of stable poly(lactic acid) (PLA) dispersions in water, intended for coating applications, was investigated. The newly prepared dispersion consists of PLA particles with an average diameter of 222 ± 2 nm based on dynamic light scattering (DLS) and scanning electron microscopy (SEM) analyses, at concentrations varying in the 5-22 wt % range. Xanthan gum (XG), a bacterial polysaccharide, was used as a thickening agent to modulate the viscosity of the formulations. The rheological properties of the PLA dispersions with different XG and PLA contents were studied in steady shear, amplitude sweep, and frequency sweep experiments. Under steady shear conditions, the viscosity of all the formulations showed a shear-thinning behavior similar to XG solutions in the whole investigated 1-1000 s-1 range, with values dependent on both PLA particles and XG concentrations. Amplitude and frequency sweep data revealed a weak-gel behavior except in the case of the most diluted sample, with moduli dependent on both PLA and XG contents. A unified scaling parameter was identified in the volume fraction (ϕ) of the PLA particles, calculated by considering the dependence of the continuous phase density on the XG concentration. Accordingly, a master curve at different volume fractions was built using the time-concentration-superposition approach. The master curve describes the rheological response of the system over a wider frequency window than the experimentally accessible one and reveals the presence of a superimposed β relaxation process in the high-frequency region.
... 106 PLA/ PBAT materials made by blown film extrusion process improved the crystalline nature with improved thermo-mechanical properties. 107 The addition of powdered extract of rosemary with PLA improved the rheological properties, antibacterial and antioxidant effects, and biocompatibility. Rosemary alone was found to increase the T g value, but PEG addition decreased the T g value. ...
Three-dimensional (3D) printing is a pioneering technology that has gained increased popularity in the fields of tissue engineering, drug design, drug delivery systems and biomedical devices. Thus, it enables us to explore this technique for fabricating 3D-printed catheters. Owing to its enhanced productivity and cost-efficiency, this technique can be utilized to fabricate any material for manufacturing or designing catheters with antimicrobial properties. From 1930s, Foley's catheter had been widely used to drain the urinary bladder of patients with impaired bladder function. Despite the complications like catheter-associated urinary tract infections (CAUTIs), kidney damage, chronic infections, encrustations and personal discomfort during inflation of the balloon, Foley's catheter was used universally without any changes in product design. Currently, marketed catheters have been reported for reducing CAUTI, but the prevention of limitations by coating drugs onto the catheter is very expensive. Altering the physical properties of the catheter by biopolymer blend might ease the discomfort. Thus, new technologies have to be adopted to manufacture ideal catheters that are biocompatible and provide antimicrobial and anti-fouling properties. Herein, we provide an overview of 3D printing techniques along with different materials opted for manufacturing catheters to overcome the existing challenges and limitations.
