Current Applied Polymer Science
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Published By Bentham Science

2452-2716

2022 ◽  
Vol 05 ◽  
Author(s):  
Wanda Jones ◽  
Bedanga Sapkota ◽  
Brian Simpson ◽  
Tarig A. Hassan ◽  
Shaik Jeelani ◽  
...  

Background: Thermoplastic expandable microspheres (TEMs) are spherical particles that consist of polymer shell encapsulating a low boiling point liquid hydrocarbon that acts as the blowing agent. When TEMs are heated at 80-190 C, the polymer shell softens and the hydrocarbon gasifies, causing the microspheres expand leading to increase in volume and decrease in density. TEMs are used in food packaging, elastomeric cool roof coatings, shoe soles, fiber and paper board, and various applications in the automotive industry. It is noted that TEMs are known by its brand name ‘Expancel’ which is also used to refer TEMs in this paper. Objective: The objective of this work was to develop and characterize forms prepared from TEMs with/without carbon nanofibers (CNFs) coatings to study the effect of CNFs on structural, thermal, and mechanical properties. Method: Sonochemical method was used to coat TEMs with various weight percentage (1, 2, and 3 %) of CNF. Neat foam (without CNF) and composite foams (TEMs coated with various wt.% of CNF) were prepared by compression molding the TEMs and TEMs-CNF composites powders. Thermal and mechanical properties of the neat and composite foams were investigated. Result: The mechanical properties of the composite foam were notably improved, which is exhibited by a 54% increase in flexural modulus and a 6% decrease in failure strain with the TEMs-(2 wt.% CNF) composite foam as compared to the neat foam. Improvement in thermal properties of composite foam was demonstrated by a 38% increase in thermal stability at 800 ºC with the TEMs-(1 wt.% CNF) composite foam as compared to the neat foam. However, no change in glass transition of TEMs was observed with the CNF coating. SEM-based analysis revealed that CNFs were well dispersed throughout the volume of the TEMs matrix forming a strong interface. Conclusions: Straightforward sonochemical method successfully triggered efficient coating of TEMs with CNFs resulting to strong adhesion interface. The mechanical properties of composite foams increased up to 2% of CNFs coating and then decreased with the higher coating presumably due to interwoven bundles and aggregation of CNFs, which might have acted as critical flaws to initiate and propagate cracking. Thermal properties of foams increased with the CNFs coating while no change in glass transition temperature was observed due to coating.


2021 ◽  
Vol 04 ◽  
Author(s):  
Ipsita Chinya ◽  
Ranjan Sen ◽  
Anirban Dhar

Background: A polymer as a host in the optical waveguide has many advantages and, when doped with rare-earth (RE) elements, offers an efficient connection, compared to its glass-based counterparts as an amplifier. However, a polymer matrix causes the concentration quenching effect of REs in the polymer matrix, making the fabrication of RE-doped polymer waveguides more complicated as compared to the fabrication of glass-based complements. Moreover, controlling scattering loss at the particle-polymer interface for maintaining the optical clarity of the composite is also a great challenge. Objective: The main aim of the present study was to optimize the synthesis of Er2O3grafted Polymethylmethacrylate (PMMA)-Polystyrene (PS) composite based transparent ternary nanocomposite and its characterization to implement them as a potential material for active core in Polymer Optical Preform (POP). Methods: Nano Erbium Oxide (Er2O3) was successfully synthesized by the wet-chemical method and encapsulated by a polymerizable surfactant, i.e., 3-Methacyloxypropyltrimethoxy silane (MPS). The encapsulated nanoparticles were further subjected to grafting with PMMA using in-situ polymerization of methyl methacrylate (MMA) followed by blending with PS via solvent mixing technique. Results: The optical transparency of the ternary composite was achieved by fine-tuning the diameter (15-20 nm) of the PMMA coated Er2O3. The crystallinity present in Er2O3 was significantly reduced after PMMA coating. The comparatively higher refractive index obtained at 589 nm wavelength for the synthesized material indicated its usability as active core material in the presence of a commercial acrylate cladding tube. A photoluminescence (Pl) study indicated that the technique might be used for a higher level of Er3+doping in polymer matrix without sacrificing its transparency. Conclusion: The obtained results indicated that the sample synthesized with the adopted technique gives better Pl intensity compared to the other methods of Er3+ incorporation in polymer optical preform (POP).


2021 ◽  
Vol 04 ◽  
Author(s):  
Ouassim Hamdi ◽  
Denis Rodrigue

: Auxetic materials have high potential due to their exceptional properties resulting from their negative Poisson ratio. Recently, several auxetic polymer-based materials have been developed. In fact, several applications are looking for a lightweight (less material consumed in production and transport) while having high mechanical performances (impact absorption, rigidity, strength, resistance, etc.). So, a balance between density and toughness/strength is of high importance, especially for military, sporting, and transport applications. So auxetic materials (especially foams) can provide high impact protection while limiting the material’s weight. This article presents a review of recent advances with a focus on auxetic polymers, with particular emphasis on the auxetic polymer foams in terms of their fabrication methods and processing conditions (depending on the nature of the cellular structure), the effect of the fabrication parameters on their final properties, as well as their models and potential applications.


2021 ◽  
Vol 04 ◽  
Author(s):  
Anna L.M.M. Toledo ◽  
Talita N. da Silva ◽  
Arianne C. dos S. Vaucher ◽  
Arthur H. V. Miranda ◽  
Gabriela C. C. Silva de Miranda ◽  
...  

Background: The demand for novel biomaterials has been exponentially rising in the last years as well as the searching for new technologies able to produce more efficient products in both drug delivery systems and regenerative medicine. Objective: The technique that can pretty well encompass the needs for novel and high-end materials with a relatively low-cost and easy operation is the electrospinning of polymer solutions. Methods: Electrospinning usually produces ultrathin fibers that can be applied in a myriad of biomedical devices including sustained delivery systems for drugs, proteins, biomolecules, hormones, etc that can be applied in a broad spectrum of applications, from transdermal patches to cancer-related drugs. Results: Electrospun fibers can be produced to mimic certain tissues of the human body, being an option to create new scaffolds for implants with several advantages. Conclusions: In this review, we aimed to encompass the use of electrospun fibers in the field of biomedical devices, more specifically in the use of electrospun nanofibers applications toward the production of drug delivery systems and scaffolds for tissue regeneration.


2021 ◽  
Vol 04 ◽  
Author(s):  
Chaitrali M Bidikar ◽  
Poonam R Inamdar

Background: Natural polymers are fascinating category of small chain molecules originating for the natural resources, and few examples include Sodium Alginate and Xanthan Gum which are water-soluble in the nature; used for mainly food packaging, biomedical and pharmaceutical applications. In proposed research work, an effort was made to overcome the polymer challenges emerging from the development of polymer blends, as the miscibility between polymers, is a vital aspect. Objective: This work focuses on the miscibility studies of natural origin polymers. In regards to that, Sodium Alginate/ Xanthan Gum blends were prepared in variable concentrations in aqueous medium and it was utilized for viscosity analysis, FTIR, Ultraviolet spectroscopic studies at variable temperatures. Methods: It was observed that the developed, Sodium Alginate / Xanthan Gum blends are miscible with each other at most of the temperatures (at 20°C, 40°C and 60°C) considering their viscosity parameters, FTIR and UV spectral data. Results: Viscosity studies revealed that the miscibility windows of polymeric ratio increases as the temperature increases whereas FTIR spectral patterns exhibited that the composition having 60:40 ratio of polymers exhibits high intensity stretches and represented to be miscible when compared to other combinations. Conclusion: The present study has reported the simple and efficient method in exploration of the miscibility windows of Sodium alginate and Xanthan gum blend.


2021 ◽  
Vol 04 ◽  
Author(s):  
Diego Moreira Schlemper ◽  
Sérgio Henrique Pezzin

: Self-healing coatings are intended to increase long-term durability and reliability and can be enabled by the presence of microcapsules containing a self-healing agent capable of interacting with the matrix and regenerating the system. This review article provides an overview of the state-of-the-art, focusing on the patents published in the field of microcapsule-based self-healing organic coatings, since the early 2000’s. A discussion about coatings for corrosion protection and the different self-healing approaches and mechanisms are also addressed, as well as future challenges and expectations for this kind of coatings.


2021 ◽  
Vol 04 ◽  
Author(s):  
Nadia Gallouze ◽  
Naima Belhaneche-Bensemrab ◽  
Sophie Commereuc ◽  
Vincent Verney

Objective: The objective of this work is the study of artificial ageing of semi-rigid and plasticized polyvinyl chloride (PVC) stabilized with epoxidized sunflower oil (ESO) as biobased derivative in combination with zinc and calcium stearates. Materials and Methods: For comparison, a formulation of PVC plasticized and stabilized with epoxidized soya bean oil (ESBO) was considered. Artificial ageing was carried out during the 304 hours. Samples were taken off after: 48, 146, 234 and 304 hours and then characterized. The evolution of density, glass transition temperature and morphology, was followed as a function of the time. The structural modifications of polymer were analyzed by Fourier transform infrared spectroscopy in attenuated total reflectance and transmission modes. Results: The results showed a little decrease of density, a considerable increase of the glass transition temperatures values and a change of morphology. All changes in the properties of PVC relate to formation of new chemical structures. Conclusion: Globally, it was found that ESO exhibited similar performances to those of ESBO


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