Theory and Simulation of Polymers at Interfaces

MRS Bulletin ◽  
1997 ◽  
Vol 22 (1) ◽  
pp. 13-15 ◽  
Author(s):  
Anna C. Balazs
Keyword(s):  
Mechanical Properties ◽  
Polymer Films ◽  
Colloidal Particles ◽  
Structural Integrity ◽  
Solid Surfaces ◽  
Polymer Layer ◽  
Polymer Interfaces ◽  
New Materials ◽  
Immiscible Polymers ◽  
The Individual

The articles in this issue illustrate how various theoretical and computer models have been used to probe behavior of polymers at penetrable and impenetrable interfaces. Interest in polymer interfaces stems from the control interfaces commonly have over macroscopic properties—such as the strength or biocompatibility of the material. Consider the “alloying” or blending of existing polymers. This technique provides an inexpensive means of fabricating new materials that can display the desirable properties of the individual components. Most polymer pairs however are immiscible, and the mixture segregates into macroscopic domains separated by relatively weak interfaces. To enhance the structural integrity of the blend, copolymer “compatibilizers” are added to the mixture. These chains localize at the interface between the immiscible polymers, enhance the adhesion between the phase-separated regions, and thereby improve the mechanical properties of the blend.On an impenetrable interface, polymer films or coatings are commonly used to modify the properties of the underlying substrate. For example the polymer layer can be utilized to tailor biocompatibility, wettability, or roughness of the surface. Polymers anchored to solid surfaces can also be used to control the interaction between these surfaces. Thus the tethered layer can promote the adhesion between dissimilar solids or prevent the aggregation of colloidal particles.

scholarly journals The Use of a Hybrid Pillar and Its Importance for Aesthetic Rehabilitation and Tissue Stability: A Clinical Report

2018 ◽  
Vol 2018 ◽  
pp. 1-6
Author(s):  
Guilherme da Gama Ramos ◽  
Danilo Lazzari Ciotti ◽  
Samuel Rehder Wimmers Ferreira ◽  
Maide Rehder Wimmers Ferreira Margarido ◽  
Raquel Adriano Dantas ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Clinical Case ◽  
Clinical Report ◽  
New Materials ◽  
Metal Free ◽  
The Past ◽  
Secondary Role ◽  
The Individual

In the past, aesthetics had a secondary role in implant rehabilitation. Nowadays, the search for a perfect and harmonious aesthetic has stimulated the development of new materials and techniques. Due to this aesthetic requirement, the hybrid abutment (titanium link + zirconia) emerged as an alternative to metallic pillars. The hybrid abutment made a more favorable aesthetic possible, provided reliable mechanical properties, and increased biocompatibility to the surrounding tissues. Additionally, the individual zirconia abutment improves the emergency profile and the final white aesthetics. The objective of this paper is to report a clinical case with a manufactured individualized hybrid abutment for a metal-free indirect restoration, showing the applicability, mechanical properties, and biocompatibility of the hybrid abutment.

scholarly journals INVESTIGATION OF IMPACT OF CROSSLINKING AGENTS ON CHARACTERISTICS OF SPATIAL NET AND PROPERTIES OF STYRENE-ACRYLIC POLYMER FILMS

2018 ◽  
Vol 61 (7) ◽  
pp. 68
Author(s):  
Inna Slepchuk ◽  
Olga Ya. Semeshko ◽  
Tatiana S. Asaulyuk ◽  
Yuliya G. Saribekova
Keyword(s):  
Mechanical Properties ◽  
Polymer Film ◽  
Polymer Films ◽  
Crosslinking Agent ◽  
Hydrolytic Degradation ◽  
Physical And Mechanical Properties ◽  
Acrylic Polymer ◽  
The Individual ◽  
High Degree ◽  
Crosslinking Agents

The influence of crosslinking agents on the characteristics and properties of films from aqueous dispersions of styrene-acrylic polymers Lacritex 309, 430 and 640 was studied in order to obtain coatings on textile materials. Mono-, di- and triglycidyl esters are chosen as crosslinking agents. The choice of aqueous dispersions of polymers and crosslinkers is due to strict environmental requirements for textile products. By determining the amount of aceton-insoluble fractions of the formed polymer films, it was determined that the incorporation of crosslinkers is required in the Lacritex dispersion 640, and the films based on Lacritex 430 and 309 are distinguished by a high degree of intermolecular crosslinking. Optimum concentrations of crosslinkers have been established, which provide a high degree of curing of Lacritex 640. Using the sol-gel method, the structural parameters of the spatial nets of styrene-acrylic polymers (the part of sol fraction, the degree of crosslinking, the part of active chains, the average molecular weight of the chain segment, the crosslink density) were calculated. The polymer films from the individual polymer Lacritex 430 have the highest indexes of physic mechanical characteristics. Lacritex 640/Laproxide 703 compositions can be used as polymer matrixes for textile materials. The formation of crosslinks of hydroxyl and carboxyl groups of the styrene-acrylic polymer with epoxy groups of the crosslinking agent was confirmed by IR spectroscopy. The investigation of the effect of water and soap-soda treatments at various temperatures shows that the films under study have high resistance to water and soap-soda solution. The results of investigation of the tensile strength, the elongation at break, the hardness of the coating surface by the Koenig method and the stickiness according to the FINAT method (Test Method Number 9) of the formed polymer films indicate high physical and mechanical properties such as increased mechanical strength and elasticity, reduced hardness and tackiness. Thus, based on the studies carried out, it can be concluded that the individual styrene-acrylic Lacritex polymers 309 and 430 provide the formation of a strong three-dimensional spatial structure of the polymer film and can be used without crosslinking agents. The use of Lacritex 640 is possible in the composition together with the Laproxide 703 crosslinking agent at an optimum concentration of 4%. A polymer film based on this composition has a high degree of crosslinking, and as a result, increased resistance to organic solvents, reduced hydrolytic degradation at high temperatures, and increased physico-mechanical properties. A polymer film based on this composition has a high degree of crosslinking, hence, has increased resistance to organic solvents, reduced hydrolytic degradation at high temperatures, and increased physical and mechanical properties. Forcitation:Slepchuk I., Semeshko O.Ya., Asaulyuk T.S., Saribekova Yu.G. Investigation of impact of rosslinking agents on characteristics of spatial net and properties of styrene-acrylic polymer films. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2018. V. 61. N 7. P. 67-75

scholarly journals Influence of Different Percentages of Binders on the Physico-Mechanical Properties of Rhizophora spp. Particleboard as Natural-Based Tissue-Equivalent Phantom for Radiation Dosimetry Applications

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1868
Author(s):  
Siti Hajar Zuber ◽  
Nurul Ab. Aziz Hashikin ◽  
Mohd Fahmi Mohd Yusof ◽  
Mohd Zahri Abdul Aziz ◽  
Rokiah Hashim
Keyword(s):  
Mechanical Properties ◽  
Radiation Dosimetry ◽  
Structural Integrity ◽  
Soy Flour ◽  
Lower Percentage ◽  
Internal Bonding ◽  
X Ray ◽  
Tissue Equivalent ◽  
Tissue Equivalent Phantom ◽  
Edx Analyses

Rhizophora spp. particleboard with the incorporation of lignin and soy flour as binders were fabricated and the influence of different percentages of lignin and soy flour (0%, 6% and 12%) on the physico-mechanical properties of the particleboard were studied. The samples were characterised by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), X-ray fluorescence (XRF) and internal bonding. The results stipulated that the addition of binders in the fabrication of the particleboard did not change the functional groups according to the FTIR spectrum. For XRD, addition of binders did not reveal any major transformation within the composites. SEM and EDX analyses for all percentages of binders added showed no apparent disparity; however, it is important to note that the incorporation of binders allows better bonding between the molecules. In XRF analysis, lower percentage of chlorine in the adhesive-bonded samples may be advantageous in maintaining the natural properties of the particleboard. In internal bonding, increased internal bond strength in samples with binders may indicate better structural integrity and physico-mechanical strength. In conclusion, the incorporation of lignin and soy flour as binders may potentially strengthen and fortify the particleboard, thus, can be a reliable phantom in radiation dosimetry applications.

Polylactide-based stent coatings: biodegradable polymeric coatings capable of maintaining sustained release of the thrombolytic enzyme streptokinase

2020 ◽  
Vol 92 (8) ◽  
pp. 1329-1340
Author(s):  
A. G. Kolmakov ◽  
A. S. Baikin ◽  
S. V. Gudkov ◽  
K. N. Belosludtsev ◽  
E. O. Nasakina ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Polymer Films ◽  
De Novo ◽  
Membrane Surface ◽  
Aqueous Media ◽  
Polymeric Coatings ◽  
Short Term ◽  
Thrombolytic Activity ◽  
Viable Cells ◽  
Nitinol Stents

AbstractThe paper describes synthesis and testing of novel biodegradable polylactide-based polymer membranes with desired mechanical properties, which are capable of sustained and directed release of biomacromolecules with high molecular weight (in particular, streptokinase; m.w. 47 kDa). Streptokinase is a pharmaceutical agent, possessing a pronounced thrombolytic activity. The membranes synthesized had a percentage elongation of 2–11% and tensile strength of 25–85 MPa. They were biodegradable – yet being stored in aqueous media in the absence of biological objects, would be dissolved by no more than 10% in 6 months. The synthesized membranes were capable of controlled release of streptokinase into the intercellular space, with the enzyme retaining more than 90% of its initial activity. The rate of streptokinase release from the membranes varied from 0.01 to 0.04 mg/day per cm2 of membrane surface. The membrane samples tested in the work did not have any short-term toxic effects on the cells growing de novo on the membrane surface. The mitotic index of those cells was approximately 1.5%, and the number of non-viable cells on the surface of the polymer films did not exceed 3–4% of their total amount. The implantation of the synthesized polymers – as both individual films and coatings of nitinol stents – was not accompanied by any postoperative complications. The subsequent histological examination revealed no abnormalities. Two months after the implantation of polymer films, only traces of polylactide were found in the implant-surrounding tissues. The implantation of stents coated with streptokinase-containing polymers resulted in the formation of a mature and thick connective-tissue capsules. Thus, the polylactide membranes synthesized and tested in this work are biodegradable, possess the necessary mechanical properties and are capable of sustained and directed release of streptokinase macromolecules.

scholarly journals Characterization of Mechanical Heterogeneity in Dissimilar Metal Welded Joints

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4145
Author(s):  
He Xue ◽  
Zheng Wang ◽  
Shuai Wang ◽  
Jinxuan He ◽  
Hongliang Yang
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Welded Joints ◽  
Structural Integrity ◽  
Material Interfaces ◽  
Mechanical Heterogeneity ◽  
Finite Element Software ◽  
Dissimilar Metal ◽  
Stress Changes

Dissimilar metal welded joints (DMWJs) possess significant localized mechanical heterogeneity. Using finite element software ABAQUS with the User-defined Material (UMAT) subroutine, this study proposed a constitutive equation that may be used to express the heterogeneous mechanical properties of the heat-affected and fusion zones at the interfaces in DMWJs. By eliminating sudden stress changes at the material interfaces, the proposed approach provides a more realistic and accurate characterization of the mechanical heterogeneity in the local regions of DMWJs than existing methods. As such, the proposed approach enables the structural integrity of DMWJs to be analyzed in greater detail.

The mechanical properties of polymer–colloid hybrid hydrogels

Soft Matter ◽  
2017 ◽  
Vol 13 (27) ◽  
pp. 4786-4790 ◽  
Author(s):  
H. Dehne ◽  
F. M. Hecht ◽  
A. R. Bausch
Keyword(s):  
Mechanical Properties ◽  
Functional Properties ◽  
Colloidal Particles ◽  
Hybrid Gels ◽  
Hybrid Hydrogels ◽  
Polymer Colloid

The incorporation of monodisperse colloidal particles in hydrogels is a promising approach to create hybrid gels with unique structural, mechanical and functional properties.

Effect of graphite and silicon carbide fillers on mechanical properties of PA6 polymer composites

2017 ◽  
Vol 37 (6) ◽  
pp. 547-557 ◽  
Author(s):  
Sekaran Sathees Kumar ◽  
Ganesan Kanagaraj
Keyword(s):  
Mechanical Properties ◽  
Silicon Carbide ◽  
Polymer Composites ◽  
Interfacial Adhesion ◽  
Hybrid Composites ◽  
Fracture Morphology ◽  
Tensile Fracture ◽  
Injection Molded ◽  
The Individual

Abstract In this paper, the combined effect of different weight percentages of silicon carbide (SiC) and graphite (Gr) reinforcement on the mechanical properties of polyamide (PA6) composite is studied. Test specimens of pure PA6, 85 wt% PA6+10 wt% SiC+5 wt% Gr and 85 wt% PA6+5 wt% SiC+10 wt% Gr are prepared using an injection molding machine. The tensile, impact, hardness, morphology and thermal properties of the injection molded composites were investigated. The obtained results showed that mechanical properties, such as tensile and impact strength and modulus of the PA6 composites, were significantly higher than the pure PA6, and hybridization with silicon carbide and graphite further enhanced the performance properties, as well as the thermal resistance of the composites. The tensile fracture morphology and the characterization of PA6 polymer composites were observed by scanning electron microscope (SEM) and Fourier transform infrared spectroscopic methods. SEM observation of the fracture surfaces showed the fine dispersion of SiC and Gr for strong interfacial adhesion between fibers and matrix. The individual and combined reinforcing effects of silicon carbide and graphite on the mechanical properties of PA6 hybrid composites were compared and interpreted in this study. Improved mechanical properties were observed by the addition of small amount of SiC and Gr concurrently reinforced with the pure PA6. Finally, thermogravimetric analysis showed that the heat resistance of the composites tended to increase with increasing silicon carbide and graphite content simultaneously.

A New Model for Biologic Constructs: Biotensegrity

2003 ◽  
Author(s):  
Stephen M. Levin
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Gone With The Wind ◽  
New Model ◽  
Automobile Parts ◽  
Finite Element Meshes ◽  
The Individual ◽  
Central Factory ◽  
Model Structures ◽  
As If

Present biologic models envision organisms behave like the character ‘Topsy’ in Gone with the Wind; they “just grew.” Modeled of Lego©-like components, the individual structures are linked together as if they are automobile parts that are manufactured at different plants and assembled at some central factory. For the most part, hexahedral finite element meshes are used to model structures. When tetrahedral modeling is used, no account is made of the different mechanical properties that are inherent in triangulated structures, (trusses), that make the structures behave very differently than hexahedral-based models.

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