polymer composition
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Pharmaceutics ◽  
2022 ◽  
Vol 14 (1) ◽  
pp. 158
Author(s):  
Anna Clara De Felice ◽  
Valerio Di Di Lisio ◽  
Iolanda Francolini ◽  
Alessia Mariano ◽  
Antonella Piozzi ◽  
...  

Polylactides (PLAs) are a class of polymers that are very appealing in biomedical applications due to their degradability in nontoxic products, tunable structural, and mechanical properties. However, they have some drawbacks related to their high hydrophobicity, lack of functional groups able to graft bioactive molecules, and solubility in unsafe solvents. To circumvent these shortcomings, porous scaffolds for tissue engineering were prepared by vigorously mixing a solution of isotactic and atactic PLA in nontoxic ethyl acetate at 70 °C with a water solution of choline taurinate. The partial aminolysis of the polymer ester bonds by taurine -NH2 brought about the formation of PLA oligomers with surfactant activity that stabilized the water-in-oil emulsion. Upon drying, a negligible shrinking occurred, and mechanically stable porous scaffolds were obtained. By varying the polymer composition and choline taurinate concentration, it was possible to modulate the pore dimensions (30–50 µm) and mechanical properties (Young’s moduli: 1–6 MPa) of the samples. Furthermore, the grafted choline taurinate made the surface of the PLA films hydrophilic, as observed by contact angle measurements (advancing contact angle: 76°; receding contact angle: 40°–13°). The preparation method was very simple because it was based on a one-pot mild reaction that did not require an additional purification step, as all the employed chemicals were nontoxic.


2022 ◽  
Vol 8 ◽  
Author(s):  
Bavo De Witte ◽  
Ana I. Catarino ◽  
Loes Vandecasteele ◽  
Michael Dekimpe ◽  
Nelle Meyers ◽  
...  

Monitoring the occurrence and trends of microplastic contamination in the marine environment is key to establish microplastic (MP) data baselines, to work out policy mitigation measures, and to assess the effectiveness of waste regulations. To establish MP contamination baselines in the marine environment, marine biota species can be selected as monitoring matrices to track plastic pollution in the environment. The aim of this work was to evaluate the feasibility of biomonitoring MPs in fish gastrointestinal tract (GIT). A selection of suitable fish species was performed, based on species distribution, sampling effort, commercial value of species, sustainable development of fish populations, migration behaviour, and scientific evidence for occurrence of MPs in the fish GIT. Sampling and MP extraction protocols were developed and validated on fish GIT samples acquired in the Southern North Sea. The fish species selection protocol enabled the selection of ubiquitous distributed and non-endangered fish species relevant for MP monitoring in the North Sea. The fish GIT sampling protocol considered background contamination measures and sampling fillet as procedural blanks. Advantages and disadvantages of onboard dissection were discussed. The MPs extraction protocol was based on matrix digestion, density separation, and Nile red staining of particles followed by fluorescent microscopy observation. The confirmation of MPs identification and the analysis of the polymer composition was done using micro-Fourier transform infrared (μFTIR) spectroscopy. The MP analysis indicated a low number of MPs in the fish GIT. The mean number of particles per single fish GIT was 0.48 ± 0.81 (Nile red staining observations) to 0.26 ± 0.64 (corrected for background contamination). A power analysis (sampling effort) indicated that to detect significant differences, in a balanced-ANOVA type of analysis, between species and/or sampling areas, the sample size would require a minimum of 109 up to 370 individual fish. The feasibility of MP biomonitoring in fish GIT was assessed by a SWOT-analysis, which indicated that fish GIT is a suitable matrix for biomonitoring of MPs, but that the large number of samples needed to identify significant differences can be a major drawback. A potential implementation strategy for MP biomonitoring within Europe was suggested.


2022 ◽  
pp. 118849
Author(s):  
Yelim Moon ◽  
Won Joon Shim ◽  
Gi Myung Han ◽  
Jongwook Jeong ◽  
Youna Cho ◽  
...  

Polymers ◽  
2022 ◽  
Vol 14 (1) ◽  
pp. 166
Author(s):  
Iolanda Corrado ◽  
Rocco Di Girolamo ◽  
Carlos Regalado-González ◽  
Cinzia Pezzella

Plant-derived essential oils (EOs) represent a green alternative to conventional antimicrobial agents in food preservation. Due to their volatility and instability, their application is dependent on the development of efficient encapsulation strategies allowing their protection and release control. Encapsulation in Polyhydroxyalkanoate (PHA)-based nanoparticles (NPs) addresses this challenge, providing a biodegradable and biobased material whose delivery properties can be tuned by varying polymer composition. In this work, EO from Mexican oregano was efficiently encapsulated in Polyhydroxybutyrate (PHB) and Poly-3-hydroxybutyrate-co-hydroxyhexanoate (PHB-HHx)-based NPs by solvent evaporation technique achieving high encapsulation efficiency, (>60%) and loading capacity, (about 50%). The obtained NPs displayed a regular distribution with a size range of 150–210 nm. In vitro release studies in food simulant media were fitted with the Korsmeyer–Peppas model, indicating diffusion as the main factor controlling the release. The cumulative release was affected by the polymer composition, possibly related to the more amorphous nature of the copolymer, as confirmed by WAXS and DSC analyses. Both the EO-loaded nanosystems displayed antimicrobial activity against Micrococcus luteus, with PHB-HHx-based NPs being even more effective than the pure EO. The results open the way to the effective exploitation of the developed nanosystems in active packaging.


2022 ◽  
Vol 292 ◽  
pp. 118274
Author(s):  
Andrea Camedda ◽  
Marco Matiddi ◽  
Alvise Vianello ◽  
Stefania Coppa ◽  
Jessica Bianchi ◽  
...  

Author(s):  
Olena Chulieieva ◽  
Volodymyr Zolotaryov ◽  
Volodymyr Chulieiev ◽  
Tetiana Kuleshova ◽  
Mykola Suslin

The viscoelastic properties of a halogen-free polymer composition for cable products have been investigated. The influence of temperature parameters, shear rate on the die-swell ratio of the polymer composition has been determined; the dependence of the melt density on a temperature was investigated. The polymer matrix is a mixture of polyolefins (linear low density polyethylene; polyolefin elastomer and maleic anhydride modified linear low density polyethylene) as a flame retardant filler for the polymer composition is trihydrate alumina. The content of flame retardant filler in the polymer composition is 60 %. The polymer composition was manufactured on the compounding line of X-Compound, Switzerland. The investigation of both melt density and die-swell ratio of the polymer composition has been conducted with help of capillary viscometer type IIRT-AM. To determine the density of the melt the ratio of capillary length to diameter L/D=8/2 was used. The results of the study of the dependence of the melt density of the polymer matrix from a temperature of 150–190 °C at different loads showed that this parameter decreases from 789 to 744 kg/m3 and for polymer composition from 1309 to 1268 kg/m3. The die-swell ratio in the case of an increase of the shear rate at temperatures of 150–190°C for the polymer matrix increases from 1,102 to 1,520, and for the polymer composition decreases from 1,056 to 1,018. The investigation results of the dependence of both die-swell ratio of the polymer matrix and the polymer composition on the ratio of the length of the forming tool to the diameter indicates that the die-swell ratio for the polymer matrix was reduced from 1,296 to 1,152, and for the polymer composition from 1,045 to 1,01. It was established that the viscoelastic properties of the halogen-free polymer composition are significantly influenced by: processing temperature, shear rate, melt density, the ratio of the length of the forming tool to the diameter. The research results give a possibility for a reasonable approach for the determination of technological parameters of an insulation, sheathing of power cables and optical cables of microtube construction. It will also allow to quickly adjust the geometrical parameters of the forming tool of cable heads.


Polymers ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 73
Author(s):  
Tobias Bubmann ◽  
Andreas Seidel ◽  
Holger Ruckdäschel ◽  
Volker Altstädt

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.


2021 ◽  
Vol 5 (4) ◽  
pp. 183-190
Author(s):  
M. A. Dremukhin ◽  
V. N. Nagovitsin

Reducing the time for carrying out the strength analysis of a structure in the process of manufacturing shaping tooling using modern tools of virtual computer design and modeling, namely mathematical 3D modeling in a small-scale production with the use of additive technologies, is the main task. With the help of numerical discretization, the investigated model is divided into a finite set of elements, which can take any form of the element and be defined in different reference systems. This will make it possible to predict approximately numerically the behavior of the material during its deformation under the action of the given loads applied to the 3D model. The use of additive technologies with the use of modern computer modeling, which is based on software, is an urgent task. This approach will make it possible to develop equipment with a complex geometric shape, bypassing the stage of writing control programs and performing labor-intensive operations for the primary processing of the product. This method is based on the process of constructing a 3D model of the shaping tooling that repeats the shape of the reflective surface of the reflector, using modified high-temperature engineering plastics. The process of evaluating the effectiveness of the developed model is shown on the basis of strength calculations, safety factor, deformation, static stress and displacement. The results of the work can be used in the design and manufacture of dimensionally stable products of complex geometric shapes from non-metallic materials used in the aerospace industry.


Author(s):  
B. G. Alimukhamedova ◽  
S. Sh. Tashpulatov ◽  
I. V. Cherunova

The article deals with the results of theoretical research of the use of polymer composition based on collagen to reinforce the structure of textile materials in order to prevent sliding in the seams. The calculation of the weight of polymer composition applied to the surface of textile material of garments has been presented. The dependence of the weight of polymer composition on the radius of warp and weft yarns and the width of a unit fabric structure has been determined. A formula for the volume of polymeric material has been obtained to calculate the necessary mass of the polymeric composition applied to the surface of the connection seams.


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