scholarly journals Novel Random Copolymers of Poly(butylene 1,4-cyclohexane dicarboxylate) with Outstanding Barrier Properties for Green and Sustainable Packaging: Content and Length of Aliphatic Side Chains as Efficient Tools to Tailor the Material’s Final Performance

Polymers ◽  
2018 ◽  
Vol 10 (8) ◽  
pp. 866 ◽  
Author(s):  
Giulia Guidotti ◽  
Michelina Soccio ◽  
Valentina Siracusa ◽  
Massimo Gazzano ◽  
Andrea Munari ◽  
...  
Keyword(s):  
Mechanical Response ◽  
Mechanical Characterization ◽  
Barrier Properties ◽  
Random Copolymers ◽  
Isomer Ratio ◽  
Trans Conformation ◽  
Final Performance ◽  
Alkyl Groups ◽  
Flexible Packaging ◽  
Ordered Phases

The present paper describes the synthesis of novel bio-based poly(butylene 1,4-cyclohexane dicarboxylate)-containing random copolymers for sustainable and flexible packaging applications. On one side, the linear butylene moiety has been substituted by glycol subunits with alkyl pendant groups of different length. On the other side, copolymers with different cis/trans isomer ratio of cyclohexane rings have been synthesized. The prepared samples were subjected to molecular, thermal, diffractometric, and mechanical characterization. The barrier performances to O2, CO2, and N2 gases were also evaluated. The presence of side alkyl groups did not alter the thermal stability, whereas it significantly influences the formation of ordered phases that deeply affect the functional properties, mainly in terms of mechanical response and barrier performance. In particular, the final materials present higher flexibility and significantly improved barrier properties with respect to the homopolymer and most polymers widely employed for flexible packaging. The improvement due to copolymerization was more pronounced in the case of higher co-unit-containing copolymers and for the samples with cyclohexane rings in the trans conformation.

scholarly journals Poly(Alkylene 2,5-Thiophenedicarboxylate) Polyesters: A New Class of Bio-Based High-Performance Polymers for Sustainable Packaging

Polymers ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2460
Author(s):  
Giulia Guidotti ◽  
Michelina Soccio ◽  
Massimo Gazzano ◽  
Valentina Siracusa ◽  
Nadia Lotti
Keyword(s):  
Thin Films ◽  
High Performance ◽  
Mechanical Response ◽  
Unit Length ◽  
Barrier Properties ◽  
Point Of View ◽  
Free Standing ◽  
Chain Mobility ◽  
Ordered Phases ◽  
Methylene Groups

In the present study, 100% bio-based polyesters of 2,5-thiophenedicarboxylic acid were synthesized via two-stage melt polycondensation using glycols containing 3 to 6 methylene groups. The so-prepared samples were characterised from the molecular point of view and processed into free-standing thin films. Afterward, both the purified powders and the films were subjected to structural and thermal characterisation. In the case of thin films, mechanical response and barrier properties to O2 and CO2 were also evaluated. From the results obtained, it emerged that the length of glycolic sub-units is an effective tool to modulate the chain mobility and, in turn, the kind and amount of ordered phases developed in the samples. In addition to the usual amorphous and 3D crystalline phases, in all the samples investigated it was possible to evidence a further phase characterised by a lower degree of order (mesophase) than the crystalline one, whose amount is strictly related to the glycol sub-unit length. The relative fraction of all these phases is responsible for the different mechanical and barrier performances. Last, but not least, a comparison between thiophene-based homopolymers and their furan-based homologues was carried out.

scholarly journals Visco-Hyperelastic Characterization of the Equine Immature Zona Pellucida

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1223
Author(s):  
Elisa Ficarella ◽  
Mohammad Minooei ◽  
Lorenzo Santoro ◽  
Elisabetta Toma ◽  
Bartolomeo Trentadue ◽  
...  
Keyword(s):  
Zona Pellucida ◽  
Soft Matter ◽  
Mechanical Response ◽  
Mechanical Characterization ◽  
Nonlinear Material ◽  
Prony Series ◽  
Critical Comparison ◽  
Highly Nonlinear ◽  
Good Agreement

This article presents a very detailed study on the mechanical characterization of a highly nonlinear material, the immature equine zona pellucida (ZP) membrane. The ZP is modeled as a visco-hyperelastic soft matter. The Arruda–Boyce constitutive equation and the two-term Prony series are identified as the most suitable models for describing the hyperelastic and viscous components, respectively, of the ZP’s mechanical response. Material properties are identified via inverse analysis based on nonlinear optimization which fits nanoindentation curves recorded at different rates. The suitability of the proposed approach is fully demonstrated by the very good agreement between AFM data and numerically reconstructed force–indentation curves. A critical comparison of mechanical behavior of two immature ZP membranes (i.e., equine and porcine ZPs) is also carried out considering the information on the structure of these materials available from electron microscopy investigations documented in the literature.

scholarly journals Role of smooth muscle activation in the static and dynamic mechanical characterization of human aortas

2022 ◽  
Vol 119 (3) ◽  
pp. e2117232119
Author(s):  
Giulio Franchini ◽  
Ivan D. Breslavsky ◽  
Francesco Giovanniello ◽  
Ali Kassab ◽  
Gerhard A. Holzapfel ◽  
...  
Keyword(s):  
Experimental Data ◽  
Smooth Muscle ◽  
Muscle Activation ◽  
Mechanical Response ◽  
Mechanical Characterization ◽  
Viscoelastic Behavior ◽  
Material Model ◽  
Suitable Material ◽  
Dynamic Mechanical

Experimental data and a suitable material model for human aortas with smooth muscle activation are not available in the literature despite the need for developing advanced grafts; the present study closes this gap. Mechanical characterization of human descending thoracic aortas was performed with and without vascular smooth muscle (VSM) activation. Specimens were taken from 13 heart-beating donors. The aortic segments were cooled in Belzer UW solution during transport and tested within a few hours after explantation. VSM activation was achieved through the use of potassium depolarization and noradrenaline as vasoactive agents. In addition to isometric activation experiments, the quasistatic passive and active stress–strain curves were obtained for circumferential and longitudinal strips of the aortic material. This characterization made it possible to create an original mechanical model of the active aortic material that accurately fits the experimental data. The dynamic mechanical characterization was executed using cyclic strain at different frequencies of physiological interest. An initial prestretch, which corresponded to the physiological conditions, was applied before cyclic loading. Dynamic tests made it possible to identify the differences in the viscoelastic behavior of the passive and active tissue. This work illustrates the importance of VSM activation for the static and dynamic mechanical response of human aortas. Most importantly, this study provides material data and a material model for the development of a future generation of active aortic grafts that mimic natural behavior and help regulate blood pressure.

scholarly journals Mechanical Characterization of Nanocomposite Joints Based on Biomedical Grade Polyethylene under Cyclical Loads

Polymers ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 2681
Author(s):  
Annamaria Visco ◽  
Cristina Scolaro ◽  
Antonino Quattrocchi ◽  
Roberto Montanini
Keyword(s):  
Titanium Dioxide ◽  
Mechanical Response ◽  
Mechanical Characterization ◽  
Laser Light ◽  
Mechanical Tests ◽  
Fatigue Tests ◽  
Weight Content ◽  
Percentage Weight ◽  
Static Mechanical

Polymeric joints, made of biomedical polyethylene (UHMWPE) nanocomposite sheets, were welded with a diode laser. Since polyethylene does not absorb laser light, nanocomposites were prepared containing different percentages by weight of titanium dioxide as it is a laser absorbent. The joints were first analyzed with static mechanical tests to establish the best percentage weight content of filler that had the best mechanical response. Then, the nanocomposites containing 1 wt% titanium dioxide were selected (white color) to be subjected to fatigue tests. The experimental results were also compared with those obtained on UMMWPE with a different laser light absorbent nano filler (carbon, with greater laser absorbing power, gray in color), already studied by our research team. The results showed that the two types of joints had an appreciable resistance to fatigue, depending on the various loads imposed. Therefore, they can be chosen in different applications of UHMWPE, depending on the stresses imposed during their use.

Mechanical Characterization of the Decellularized Porcine Small Intestinal Submucosa Extracellular Matrix

2013 ◽  
Author(s):  
Shijia Zhao ◽  
Linxia Gu ◽  
James M. Hammel ◽  
Haili Lang
Keyword(s):  
Mechanical Properties ◽  
Extracellular Matrix ◽  
Mechanical Response ◽  
Mechanical Characterization ◽  
Small Intestinal Submucosa ◽  
Trade Name ◽  
Porcine Small Intestinal Submucosa ◽  
Small Intestinal ◽  
Intestinal Submucosa

In this work, the decellularized porcine small intestinal submucosa extracellular matrix (SIS-ECM), obtained from the commercial product under the trade name of CorMatrix, were tested in uniaxial tension. Preconditioning under cyclic loading of 2 N was conducted to stabilize the mechanical response of the tissue. The influence of rehydration time on the mechanical properties of the tissue was evaluated. Results suggested that the stiffness of SIS-ECM decreased with longer rehydration time. Considering the application of CorMatrix in pericardial closure, the native pericardium samples were also tested. The comparison indicated that the native pericardium is softer than rehydrated CorMatrix. This work can facilitate the surgeons to better choose the appropriate rehydration time when conducting the extracardiac implantations, such as pericardial reconstruction, pericardial closure, etc.

High‐pressure processing effects on the barrier properties of flexible packaging materials

2020 ◽  
Vol 44 (11) ◽  
Author(s):  
Luís Marangoni Júnior ◽  
Rosa Maria Vercelino Alves ◽  
Christiane Quartaroli Moreira ◽  
Marcelo Cristianini ◽  
Marisa Padula ◽  
...  
Keyword(s):  
High Pressure ◽  
Barrier Properties ◽  
High Pressure Processing ◽  
Packaging Materials ◽  
Flexible Packaging ◽  
Processing Effects

scholarly journals Biomechanical Comparison of Glutaraldehyde-Crosslinked Gelatin Fibrinogen Electrospun Scaffolds to Porcine Coronary Arteries

2015 ◽  
Vol 138 (1) ◽  
Author(s):  
E. Tamimi ◽  
D. C. Ardila ◽  
D. G. Haskett ◽  
T. Doetschman ◽  
M. J. Slepian ◽  
...  
Keyword(s):  
Mechanical Response ◽  
Mechanical Characterization ◽  
Artery Bypass ◽  
Bypass Graft ◽  
Vein Grafts ◽  
Electrospun Scaffolds ◽  
Response Data ◽  
Custom Made ◽  
Biomechanical Comparison

Cardiovascular disease (CVD) is the leading cause of death for Americans. As coronary artery bypass graft surgery (CABG) remains a mainstay of therapy for CVD and native vein grafts are limited by issues of supply and lifespan, an effective readily available tissue-engineered vascular graft (TEVG) for use in CABG would provide drastic improvements in patient care. Biomechanical mismatch between vascular grafts and native vasculature has been shown to be the major cause of graft failure, and therefore, there is need for compliance-matched biocompatible TEVGs for clinical implantation. The current study investigates the biaxial mechanical characterization of acellular electrospun glutaraldehyde (GLUT) vapor-crosslinked gelatin/fibrinogen cylindrical constructs, using a custom-made microbiaxial optomechanical device (MOD). Constructs crosslinked for 2, 8, and 24 hrs are compared to mechanically characterized porcine left anterior descending coronary (LADC) artery. The mechanical response data were used for constitutive modeling using a modified Fung strain energy equation. The results showed that constructs crosslinked for 2 and 8 hrs exhibited circumferential and axial tangential moduli (ATM) similar to that of the LADC. Furthermore, the 8-hrs experimental group was the only one to compliance-match the LADC, with compliance values of 0.0006±0.00018 mm Hg−1 and 0.00071±0.00027 mm Hg−1, respectively. The results of this study show the feasibility of meeting mechanical specifications expected of native arteries through manipulating GLUT vapor crosslinking time. The comprehensive mechanical characterization of cylindrical biopolymer constructs in this study is an important first step to successfully develop a biopolymer compliance-matched TEVG.

scholarly journals Random and Diblock Thermoresponsive Oligo(ethylene glycol)-Based Copolymers Synthesized via Photo-Induced RAFT Polymerization

Polymers ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 137
Author(s):  
Alexey Sivokhin ◽  
Dmitry Orekhov ◽  
Oleg Kazantsev ◽  
Olga Sivokhina ◽  
Sergey Orekhov ◽  
...  
Keyword(s):  
Ethylene Glycol ◽  
Room Temperature ◽  
Raft Polymerization ◽  
Chain Extension ◽  
Random Copolymers ◽  
Hydrophobic Core ◽  
Polymer Backbone ◽  
Alkyl Groups ◽  
Green Led ◽  
A Chain

Amphiphilic random and diblock thermoresponsive oligo(ethylene glycol)-based (co)polymers were synthesized via photoiniferter polymerization under visible light using trithiocarbonate as a chain transfer agent. The effect of solvent, light intensity and wavelength on the rate of the process was investigated. It was shown that blue and green LED light could initiate RAFT polymerization of macromonomers without an exogenous initiator at room temperature, giving bottlebrush polymers with low dispersity at sufficiently high conversions achieved in 1–2 h. The pseudo-living mechanism of polymerization and high chain-end fidelity were confirmed by successful chain extension. Thermoresponsive properties of the copolymers in aqueous solutions were studied via turbidimetry and laser light scattering. Random copolymers of methoxy- and alkoxy oligo(ethylene glycol) methacrylates of a specified length formed unimolecular micelles in water with a hydrophobic core consisting of a polymer backbone and alkyl groups and a hydrophilic oligo(ethylene glycol) shell. In contrast, the diblock copolymer formed huge multimolecular micelles.

scholarly journals Comparative Analysis of the Mechanical Behaviour of PEF and PET Uniaxial Stretching Based on the Time/Temperature Superposition Principle

Polymers ◽  
2021 ◽  
Vol 13 (19) ◽  
pp. 3295
Author(s):  
Emilie Forestier ◽  
Christelle Combeaud ◽  
Nathanael Guigo ◽  
Guillaume Corvec ◽  
Christophe Pradille ◽  
...  
Keyword(s):  
Physical State ◽  
Mechanical Response ◽  
Superposition Principle ◽  
Barrier Properties ◽  
Experimental Conditions ◽  
Chemical Structures ◽  
Strain Induced Crystallization ◽  
Poly Ethylene ◽  
Time Temperature Superposition Principle ◽  
High Level

Poly(ethylene 2,5-furandicarboxylate), PEF and poly(ethylene terephthalate), PET, are two polyesters with close chemical structures. It leads to similar thermal, mechanical and barrier properties. In order to optimize their stretching, a strategy based on the time/temperature principle is used. The building of master curves, in the linear visco-elastic domain, allows the identification of the experimental conditions for which the two materials are in the same physical state. The initial physical state of the materials is important as, to fit with the industrial constrains, the polymers must reach high level of deformation, and develop strain induced crystallization (SIC). In this paper, the screening of the forming range is described, as well as the mechanical response depending on the stretching settings. Moreover, the same mechanical response can exist for PEF and PET if the same gap from the α-relaxation exists.

scholarly journals Performance of molecular crystals in conversion of light to mechanical work

2021 ◽  
Vol 118 (5) ◽  
pp. e2020604118
Author(s):  
Jad Mahmoud Halabi ◽  
Ejaz Ahmed ◽  
Samuel Sofela ◽  
Panče Naumov
Keyword(s):  
Microelectromechanical Systems ◽  
Mechanical Response ◽  
Mechanical Characterization ◽  
Dynamic Performance ◽  
Molecular Crystals ◽  
Performance Indices ◽  
Simulation Tools ◽  
Specific Performance ◽  
Generating Capacity ◽  
Quantitative Performance

Dynamic molecular crystals have recently received ample attention as an emerging class of energy-transducing materials, yet have fallen short of developing into fully realized actuators. Through the trans–cis surface isomerization of three crystalline azobenzene materials, here, we set out to extensively characterize the light-to-work energy conversion of photoinduced bending in molecular crystals. We distinguish the azobenzene single crystals from commonly used actuators through quantitative performance evaluation and specific performance indices. Bending molecular crystals have an operating range comparable to that of microactuators such as microelectromechanical systems and a work-generating capacity and dynamic performance that qualifies them to substitute micromotor drivers in mechanical positioning and microgripping tasks. Finite element modeling, applied to determine the surface photoisomerization parameters, allowed for predicting and optimizing the mechanical response of these materials. Utilizing mechanical characterization and numerical simulation tools proves essential in accelerating the introduction of dynamic molecular crystals into soft microrobotics applications.

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