Tuning Mechanical Properties of Biobased Polymers by Supramolecular Chain Entanglement

2019 ◽  
Vol 52 (22) ◽  
pp. 8967-8975 ◽  
Author(s):  
Meghan E. Lamm ◽  
Lingzhi Song ◽  
Zhongkai Wang ◽  
Md Anisur Rahman ◽  
Benjamin Lamm ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Chain Entanglement ◽  
Biobased Polymers ◽  
Supramolecular Chain

scholarly journals Decoupling of Mechanical and Transport Properties in Organogels via Solvent Variation

Gels ◽  
2021 ◽  
Vol 7 (2) ◽  
pp. 61
Author(s):  
Kenneth P. Mineart ◽  
Cameron Hong ◽  
Lucas A. Rankin
Keyword(s):  
Mechanical Properties ◽  
Mechanical Behavior ◽  
Transdermal Drug Delivery ◽  
Triblock Copolymer ◽  
Polymer Concentration ◽  
Mineral Oil ◽  
Solute Diffusion ◽  
Oil Viscosity ◽  
Chain Entanglement ◽  
Mineral Oils

Organogels have recently been considered as materials for transdermal drug delivery media, wherein their transport and mechanical properties are among the most important considerations. Transport through organogels has only recently been investigated and findings highlight an inextricable link between gels’ transport and mechanical properties based upon the formulated polymer concentration. Here, organogels composed of styrenic triblock copolymer and different aliphatic mineral oils, each with a unique dynamic viscosity, are characterized in terms of their quasi-static uniaxial mechanical behavior and the internal diffusion of two unique solute penetrants. Mechanical testing results indicate that variation of mineral oil viscosity does not affect gel mechanical behavior. This likely stems from negligible changes in the interactions between mineral oils and the block copolymer, which leads to consistent crosslinked network structure and chain entanglement (at a fixed polymer concentration). Conversely, results from diffusion experiments highlight that two penetrants—oleic acid (OA) and aggregated aerosol-OT (AOT)—diffuse through gels at a rate inversely proportional to mineral oil viscosity. The inverse dependence is theoretically supported by the hydrodynamic model of solute diffusion through gels. Collectively, our results show that organogel solvent variation can be used as a design parameter to tailor solute transport through gels while maintaining fixed mechanical properties.

scholarly journals Electrospun Alginate Fibers: Mixing of Two Different Poly(ethylene oxide) Grades to Improve Fiber Functional Properties

Nanomaterials ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 971 ◽  
Author(s):  
Barbara Vigani ◽  
Silvia Rossi ◽  
Giulia Milanesi ◽  
Maria Bonferoni ◽  
Giuseppina Sandri ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Ethylene Oxide ◽  
Electrospinning Process ◽  
Mechanical Resistance ◽  
Fiber Morphology ◽  
Chain Entanglement ◽  
Poly Ethylene Oxide ◽  
Alginate Fibers ◽  
Poly Ethylene ◽  
Morphology And Mechanical Properties

The aim of the present work was to investigate how the molecular weight (MW) of poly(ethylene oxide) (PEO), a synthetic polymer able to improve alginate (ALG) electrospinnability, could affect ALG-based fiber morphology and mechanical properties. Two PEO grades, having different MWs (high, h-PEO, and low, l-PEO) were blended with ALG: the concentrations of both PEOs in each mixture were defined so that each h-PEO/l-PEO combination would show the same viscosity at high shear rate. Seven ALG/h-PEO/l-PEO mixtures were prepared and characterized in terms of viscoelasticity and conductivity and, for each mixture, a complex parameter rH/rL was calculated to better identify which of the two PEO grades prevails over the other in terms of exceeding the critical entanglement concentration. Thereafter, each mixture was electrospun by varying the process parameters; the fiber morphology and mechanical properties were evaluated. Finally, viscoelastic measurements were performed to verify the formation of intermolecular hydrogen bonds between the two PEO grades and ALG. rH/rL has been proved to be the parameter that better explains the effect of the electrospinning conditions on fiber dimension. The addition of a small amount of h-PEO to l-PEO was responsible for a significant increase in fiber mechanical resistance, without affecting the nano-scale fiber size. Moreover, the mixing of h-PEO and l-PEO improved the interaction with ALG, resulting in an increase in chain entanglement degree that is functional in the electrospinning process.

scholarly journals Transparent PC/PMMA Blends with Enhanced Mechanical Properties via Reactive Compounding of Functionalized Polymers

Polymers ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 73
Author(s):  
Tobias Bubmann ◽  
Andreas Seidel ◽  
Holger Ruckdäschel ◽  
Volker Altstädt
Keyword(s):  
Mechanical Properties ◽  
Mechanical Performance ◽  
Morphological Structure ◽  
Scratch Resistance ◽  
Polymer Composition ◽  
Two Phase ◽  
Chain Entanglement ◽  
Twin Screw ◽  
Optical And Mechanical Properties ◽  
Pmma Blends

Reactive compounding of terminally phenolic OH-functionalized polycarbonate (PC) with epoxy-functionalized polymethylmethacrylate (PMMA) prepared by copolymerization with glycidyl methacrylate was investigated. It was spectroscopically demonstrated that a PC/PMMA copolymer was formed during the melt reaction of the functional groups. Zirconium acetylacetonate could catalytically accelerate this reaction. Correlations of the phenomenological (optical and mechanical) properties with the molecular level and mesoscopic (morphological) structure were discussed. By the investigated reactive compounding process, transparent PC/PMMA blends with two-phase morphologies were obtained in a continuous twin-screw extruder, which, for the first time, combined the high transmission of visible light with excellent mechanical performance (e.g., synergistically improved tensile and flexural strength and high scratch resistance). The transparency strongly depended on (a) the degree of functionalization in both PC and PMMA, (b) the presence of the catalyst, and (c) the residence time of the compounding process. The in-situ-formed PC/PMMA copolymer influenced the observed macroscopic properties by (a) a decrease in the interphase tension, leading to improved and stabilized phase dispersion, (b) the formation of a continuous gradient of the polymer composition and thus of the optical refractive indices in a diffuse mesoscopic interphase layer separating the PC and PMMA phases, and (c) an increase in the phase adhesion between PC and PMMA due to mechanical polymer chain entanglement in this interphase.

Connecting Chain Chemistry and Network Topology With the Large Deformation Mechanical Response of Elastomers

2012 ◽  
Author(s):  
Jacob D. Davidson ◽  
N. C. Goulbourne
Keyword(s):  
Mechanical Properties ◽  
Large Deformation ◽  
Network Structure ◽  
Biological Networks ◽  
Mechanical Response ◽  
Md Simulations ◽  
Matrix Formulation ◽  
Modeling Framework ◽  
Chain Entanglement ◽  
Scale Network

Elastomers are polymers able to undergo large, reversible deformations, and their mechanical properties depend on the chemistry of individual chains as well as the topology of the crosslinked network. In this work we analyze the connection between micro-scale network structure and the macroscopic mechanical properties by performing molecular dynamics (MD) simulations using the Kremer & Grest bead-spring model. The chain length and the density at which crosslinking is performed are varied in order to produce systems ranging from crosslink-dominated to highly entangled, and stress-stretch results are obtained via MD in the large deformation regime. In analogy with recent work on social, technological, and biological networks, we apply mathematical graph theory to describe elastomer networks in a multi-scale modeling framework. A matrix formulation of crosslinked polymers is presented and applied in order to identify the network structure resulting from both chemical crosslinks and physical crosslinks (entanglements). We show that spectral analysis of the crosslink and chain entanglement adjacency matrices along with the corresponding degree distributions can be used to identify and differentiate between the different materials. The spectrum of the crosslink adjacency matrix resembles a sparse regular graph, and spectrum of the intermolecular chain entanglement matrix for the highly entangled systems is shown to resemble a random graph; however, deviations are noted which require further study. A comparison of the network properties with the stress-stretch response demonstrates the influence of both crosslinks and entanglements on the large deformation mechanical behavior of an elastomer material.

scholarly journals Converting Muscle-mimetic Biomaterials to Cartilage-like Materials

2021 ◽  
Author(s):  
Linglan Fu ◽  
Lan Li ◽  
Bin Xue ◽  
Jing Jin ◽  
Yi Cao ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Articular Cartilage ◽  
Protein Unfolding ◽  
Protein Chain ◽  
Compression Tests ◽  
Chain Entanglement ◽  
Load Bearing ◽  
Protein Mechanics ◽  
High Elasticity ◽  
Soft Actuators

Load-bearing tissues, such as muscle and cartilage, exhibit mechanical properties that often combine high elasticity, high toughness and fast recovery, despite their different stiffness (~100 kPa for muscles and one to several MPa for cartilage). The advance in protein engineering and protein mechanics has made it possible to engineer protein-based biomaterials to mimic soft load-bearing tissues, such as muscles. However, it is challenging to engineer protein biomaterials to achieve the mechanical properties exhibited by stiff tissues, such as articular cartilage, or to develop stiff synthetic extracellular matrices for cartilage stem/progenitor cell differentiation. By employing physical entanglements of protein chains and force-induced protein unfolding, here we report the engineering of a highly tough and stiff protein hydrogel to mimic articular cartilage. By crosslinking an engineered artificial elastomeric protein from its unfolded state, we introduced chain entanglement into the hydrogel network. Upon renaturation, the entangled protein chain network and forced protein unfolding entailed this single network protein hydrogel with superb mechanical properties in both tensile and compression tests, showing a Youngs modulus of ~0.7 MPa and toughness of 250 kJ/m3 in tensile testing; and ~1.7 MPa in compressive modulus and toughness of 3.2 MJ/m3. The energy dissipation in both tensile and compression tests is reversible and the hydrogel can recovery its mechanical properties rapidly. Moreover, this hydrogel can withstand a compression stress of >60 MPa without failure, amongst the highest compressive strength achieved by a hydrogel. These properties are comparable to those of articular cartilage, making this protein hydrogel a novel cartilage-mimetic biomaterial. Our study opened up a new potential avenue towards engineering protein hydrogel-based substitute for articular cartilage, and may also help develop protein biomaterials with superb mechanical properties for applications in soft actuators and robotics.

scholarly journals Color Fixation Strategies on Sustainable Poly-Butylene Succinate Using Biobased Itaconic Acid

Polymers ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 79
Author(s):  
Lidia G. Quiles ◽  
Julio Vidal ◽  
Francesca Luzi ◽  
Franco Dominici ◽  
Ángel Fernández Cuello ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Itaconic Acid ◽  
The Other ◽  
Zro2 Nanoparticles ◽  
Butylene Succinate ◽  
Elongation At Break ◽  
Biobased Polymers ◽  
Hydrophilic Behavior ◽  
The Matrix ◽  
Absorbance Spectra

Biopo-lybutylene succinate (bioPBS) is gaining attention in the biodegradable polymer market due to its promising properties, such as high biodegradability and processing versatility, representing a potential sustainable replacement for fossil-based commodities. However, there is still a need to enhance its properties for certain applications, with aesthetical and mechanical properties being a challenge. The aim of the present work is to improve these properties by adding selected additives that will confer bioPBS with comparable properties to that of current counterparts such as polypropylene (PP) for specific applications in the automotive and household appliances sectors. A total of thirteen materials have been studied and compared, being twelve biocomposites containing combinations of three different additives: a commercial red colorant, itaconic acid (IA) to enhance color fixation and zirconia (ZrO2) nanoparticles to maintain at least native PBS mechanical properties. The results show that the combination of IA and the coloring agent tends to slightly yellowish the blend due to the absorbance spectra of IA and also to modify the gloss due to the formation of IA nanocrystals that affects light scattering. In addition, for low amounts of IA (4 wt %), Young’s Modulus seems to be kept while elongation at break is even raised. Unexpectedly, a strong aging affect was found after four weeks. IA increases the hydrophilic behavior of the samples and thus seems to accelerate the hydrolization of the matrix, which is accompanied by an accused disaggregation of phases and an overall softening and rigidization effect. The addition of low amounts of ZrO2 (2 wt %) seems to provide the desired effect for hardening the surface while almost not affecting the other properties; however, higher amounts tends to form aggregates saturating the compounds. As a conclusion, IA might be a good candidate for color fixing in biobased polymers.

scholarly journals The Impact of the Addition of Compatibilizers on Poly (lactic acid) (PLA) Properties after Extrusion Process

Polymers ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 2688
Author(s):  
F.A.M.M. Gonçalves ◽  
Sandra M. A. Cruz ◽  
Jorge F. J. Coelho ◽  
Arménio C. Serra
Keyword(s):  
Mechanical Properties ◽  
Lactic Acid ◽  
Extrusion Process ◽  
Poly Lactic Acid ◽  
Thermal And Mechanical Properties ◽  
Fundamental Study ◽  
Biobased Polymers ◽  
Structural Differences ◽  
The Impact ◽  
Morphology And Mechanical Properties

Poly (lactic acid) (PLA), due to its biodegradability, biocompatibility, and renewability, is one of the most promising biobased polymers for replacing some of the petrol-based materials. Low flexibility of PLA is overcome, by blending it with olefin-based polymers, such as polypropylene (PP). However, the use of compatibilizing agents is required to attain final materials with suitable mechanical properties. Such agents, although essential, can affect PLA structure and, consequently, the mechanical properties of the PLA. To the best of our knowledge, this issue was never studied, and the results can contribute to achieving the best formulations of PLA-based blends according to their final applications. The thermal and mechanical properties of the extruded PLA, with three different commercial compatibilizing agents, were evaluated with the purpose of demonstrating how the compatibilizers can introduce structural differences into the PLA chain during the extrusion process. The combination of crystallinity, molecular weight, and the morphology of the samples after extrusion determines the final mechanical properties of PLA. Despite being a fundamental study, it is our aim to contribute to the sustainability of PLA-based industries. The addition of a 2.5% concentration of C1 compatibilizer seems to have less influence on the final morphology and mechanical properties of the blends.

Chain entanglement, mechanical properties and drawability of poly(lactide)

1994 ◽  
Vol 272 (9) ◽  
pp. 1068-1081 ◽  
Author(s):  
D. W. Grijpma ◽  
J. P. Penning ◽  
A. J. Pennings
Keyword(s):  
Mechanical Properties ◽  
Chain Entanglement

Mechanical Behavior of Lightly Crosslinked Polyurethanes

1977 ◽  
Vol 50 (5) ◽  
pp. 934-944 ◽  
Author(s):  
S. Dzierża ◽  
J. Janáček
Keyword(s):  
Mechanical Properties ◽  
Hydrogen Bonding ◽  
Elevated Temperatures ◽  
Van Der Waals ◽  
Crosslinking Agent ◽  
Polymeric Materials ◽  
Van Der Waals Forces ◽  
Branch Points ◽  
Chain Entanglement ◽  
Polyurethane Elastomers

Abstract Polyurethane elastomers are a numerous group of polymeric materials of wide practical application. They are usually formed by polyaddition of diisocyanates with hydroxyl-terminated polyesters or polyethers in the presence of low molecular weight diols or diamines as chain extenders. One may consider urethane elastomers to be block copolymers, consisting of moderately flexible long linear polyester or polyether segments and relatively stiff segments of aromatic and urethane groups. The length and structure of each block can be easily controlled. Crosslinking by an excess of diisocyanate can occur only at the stiff segments, and the number of branch points can also be controlled. The properties of these elastomers can be widely changed using components of different structures and varying their quantitative ratios. They are the results of a combination of segment flexibility, crosslinking, chain entanglement, orientation of segments, hydrogen bonding and other van der Waals forces, as well as rigidity of aromatic units. In the urethane systems, hydrogen bonding and other van der Waals forces, play a much more pronounced role than in familiar olefin-derived elastomers. Although polyurethane elastomers have very good mechanical properties at room temperature, their application is strongly limited by rapid deterioration of properties which takes place at elevated temperatures. The decay of mechanical properties of polyurethane is caused by the breaking of hydrogen and other secondary bonds, as well as by the presence of relatively weak crosslinks that make up their network. The properties of polyurethanes at elevated temperatures may, perhaps, be improved by forming additional crosslinks, besides the typical ones. Some efforts concerning this problem have been published. The aim of our study was to obtain and check the properties of polyurethane elastomers having unsaturated bonds, on which some additional crosslinks were expected to be formed in the presence of a suitable crosslinking agent.

scholarly journals Colour Fixation Strategies on Sustainable Polybutylene Succinate Using Biobased Itaconic Acid

2020 ◽  
Author(s):  
Lidia García-Quiles ◽  
Julio Vidal ◽  
Debora Puglia ◽  
Franco Dominici ◽  
Ángel Fernández ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Itaconic Acid ◽  
Young Modulus ◽  
The Other ◽  
Zro2 Nanoparticles ◽  
Elongation At Break ◽  
Biobased Polymers ◽  
The Matrix ◽  
Polybutylene Succinate ◽  
Absorbance Spectra

BioPBS is gaining attention in the biodegradable polymer market due to their promising properties such as high biodegradability and processing versatility representing a potential sustainable replacement for fossil oil-based commodities. However, there is still a need to enhance its properties for certain applications, being aesthetical and mechanical properties a challenge. The aim of the present work is to improve these properties by adding selected additives that will confer bioPBS with comparable properties to that of current counterparts such as polypropylene (PP) for specific applications in the automotive and household appliances sectors. A total of thirteen materials have been studied and compared, being twelve biocomposites containing combinations of three different additives: a commercial red colourant, itaconic acid (IA) to enhance colour fixation and zirconia (ZrO2) nanoparticles to maintain at least native PBS mechanical properties. Results show that the combination of IA and the colouring agent tends to slightly yellowish the blend due to the absorbance spectra of IA and also to modify the gloss due to the formation of IA nanocrystals that affects light scattering. In addition, for low amounts of IA (4wt.%), young modulus seems to be kept while elongation at break is even raised. Unexpectedly, a strong aging affect was found after 4 weeks. IA increases the hydrophilic behaviour of the samples and thus seems to accelerate the hydrolisation of the matrix, which is accompanied by an accused disaggregation of phases and an overall softening and rigidization effect. The addition of low amounts of ZrO2 (2wt.%) seems to provide the desired effect for hardening the surface while almost not affecting the other properties; however, higher amounts tends to form aggregates saturating the compounds. As a conclusion, IA might be a good candidate for colour fixing in biobased polymers.

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