Artigos de revistas: "Solventless processing"

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Brandão, Lúcia, Júlio Viana, David G. Bucknall e Gabriel Bernardo. "Solventless processing of conjugated polymers—A review". Synthetic Metals 197 (novembro de 2014): 23–33. http://dx.doi.org/10.1016/j.synthmet.2014.08.003.

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Jaimini, Manish, Arpit Jain, Sanjay K. Sharma e Shailender Mohan. "Solventless coating for Tablets: An alternative to conventional coating technique". Indian Journal of Pharmaceutical and Biological Research 2, n.º 02 (30 de junho de 2014): 108–14. http://dx.doi.org/10.30750/ijpbr.2.2.18.

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There are many ways to coat tablets. Coatings are a very important part in the formulation of pharmaceutical dosage form to achieve excellent formulation quality (e.g., color, texture, mouth feel, and taste masking), physical and chemical protection for the drugs in the dosage forms, and modification of drug release characteristics. Most film coatings are applied as aqueous or organic-based polymer solutions. Such film coating brings their own disadvantages. Solventless coatings are alternative technique of coating. Solventless coating technologies can overcome many of the disadvantages associated with the use of solvents (e.g., solvent exposure, solvent disposal, and residual solvent in product) in pharmaceutical coating. Solventless processing reduces the overall cost by eliminating the tedious and expensive processes of solvent disposal/treatment. In addition, it can significantly reduce the processing time due to reduction of step of drying/evaporation. These environment-friendly processes are performed without any heat in most cases (except hot-melt coating) and thus can provide an alternative technology to coat temperature-sensitive drugs. This review includes various solventless coating methods like magnetic assisted impaction coating , hotmelt coating, supercritical fluid spray coating, electrostatic coating, dry powder coating, and photocurable coating that can be used to coat the pharmaceutical dosage forms.

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Shamshina, Julia L., Robin S. Stein e Noureddine Abidi. "Choosing the right strategy: cryogrinding vs. ball milling – comparing apples to apples". Green Chemistry 23, n.º 23 (2021): 9646–57. http://dx.doi.org/10.1039/d1gc03128g.

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Despite many reports on ball milling (BM) of chitin, the effect of cryomilling of chitin has not yet been reported, even though it is a solventless and environmentally-friendly method for the processing of chitin polymer.

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Bose, Sagarika, e Robin H. Bogner. "Solventless visible light-curable coating: I. Critical formulation and processing parameters". International Journal of Pharmaceutics 393, n.º 1-2 (junho de 2010): 32–40. http://dx.doi.org/10.1016/j.ijpharm.2010.01.041.

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Zhang, Dan, Maria G. Villarreal, Eusebio Cabrera, Avraham Benatar, L. James Lee e Jose M. Castro. "Performance study of ultrasonic assisted processing of CNT nanopaper/solventless epoxy composite". Composites Part B: Engineering 159 (fevereiro de 2019): 327–35. http://dx.doi.org/10.1016/j.compositesb.2018.10.012.

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Afzal, Adeel, Humaira Masood Siddiqi, Shaukat Saeed e Zahoor Ahmad. "Exploring resin viscosity effects in solventless processing of nano-SiO2/epoxy polymer hybrids". RSC Advances 3, n.º 12 (2013): 3885. http://dx.doi.org/10.1039/c3ra21150a.

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Ullas, A. V., Devendra Kumar e Prasun Kumar Roy. "Epoxy-Glass Microballoon Syntactic Foams: Rheological Optimization of the Processing Window". Advances in Polymer Technology 2019 (1 de abril de 2019): 1–12. http://dx.doi.org/10.1155/2019/9180302.

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In this paper, we discuss the chemorheology of epoxy based syntactic foams containing glass microballoons of varying density, with an aim of establishing the effect of microballoon loading on its processability. The primary objective is to determine the maximum microballoon loading that disperses uniformly in the resin without the aid of any diluent. The viscosity and dynamic mechanical properties of epoxy formulations containing varying amounts of glass microballoons were established by parallel plate rheometry. Our studies reveal that solventless processing of formulations with microballoon loading > 60% poses practical difficulties due to prohibitively high viscosities, although a packing efficiency of 74% is theoretically allowed in the case of hexagonal close packing. The presence of microballoons does not alter the curing mechanism. The mechanical properties of syntactic foams were inversely proportional to the loading and type of glass microballoons.

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Russo, Ethan B., Jeremy Plumb e Venetia L. Whiteley. "Novel Solventless Extraction Technique to Preserve Cannabinoid and Terpenoid Profiles of Fresh Cannabis Inflorescence". Molecules 26, n.º 18 (10 de setembro de 2021): 5496. http://dx.doi.org/10.3390/molecules26185496.

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Despite its use by humans for thousands of years, the technology of cannabis usage and extraction is still evolving. Given that the primary pharmacological compounds of interest are cannabinoid and terpenoids found in greatest abundance in capitate glandular trichomes of unfertilized female inflorescences, it is surprising that older techniques of hashish making have received less technological advancement. The purpose of this study was to employ organically grown cannabis and to isolate pure trichomes from freshly picked flowers via exposure to vapor from solid CO2, commonly known as “dry ice”, followed by their isolation via sifting through a 150 µ screens while maintaining the cold chain. Biochemical analysis was undertaken on fresh flower, frozen-sifted flower by-products, treated trichomes (Kryo-Kief™), dried flower, dried sifted flower by-product and dried kief. The dry ice process successfully concentrated cannabinoid content as high as 60.7%, with corresponding concentration and preservation of monoterpenoids encountered in fresh flower that are usually lost during the conventional cannabis drying and curing process. The resulting dried sifted flower by-product after dry ice processing remains a usable commodity. This approach may be of interest to pharmaceutical companies and supplement producers pursuing cannabis-based medicine development with an eye toward full synergy of ingredients harnessing the entourage effect.

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Polgar, L. M., J. Keizer, R. Blom, B. Niemeijer, T. de With, F. Picchioni e M. van Duin. "THERMOREVERSIBLE CROSS-LINKING OF RUBBER COMPOUNDS: FROM PROOF-OF-CONCEPT TOWARD AN INDUSTRIAL PROCESS". Rubber Chemistry and Technology 91, n.º 2 (1 de abril de 2018): 492–508. http://dx.doi.org/10.5254/rct-18-82638.

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ABSTRACT It is demonstrated that the concept of thermoreversible cross-linking of functionalized maleic anhydride grafted ethylene–propylene (EPM-g-MA) rubber using Diels–Alder chemistry is limited neither to laboratory scale using a solvent route nor to gum rubber. The use of an internal mixer is the first step toward an industrial process, since it greatly reduces the processing time and allows for a solventless process for the furan-functionalization and subsequent bismaleimide cross-linking of EPM rubber. Practical rubber compounds were prepared by mixing thermoreversibly cross-linked EPM with carbon black and mineral oil in the same batch mixer. This resulted in reinforcement of the rubber without affecting the thermoreversible character of the cross-linking. The pendant furan groups of the (non)cross-linked EPM-g-furan interact with the carbon black filler. Finally, crystalline EPM rubber compounds were prepared, which show excellent material properties and property retention over multiple reprocessing cycles.

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Osváth, Zsófia, Anita Szőke, Szabolcs Pásztor, Györgyi Szarka, László Balázs Závoczki e Béla Iván. "Post-Polymerization Heat Effect in the Production of Polyamide 6 by Bulk Quasiliving Anionic Ring-Opening Polymerization of ε-Caprolactam with Industrial Components: A Green Processing Technique". Processes 8, n.º 7 (17 de julho de 2020): 856. http://dx.doi.org/10.3390/pr8070856.

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Bulk, solventless anionic ring-opening polymerization (AROP) of ε-caprolactam (CPL) with high yields, without side products and with short reaction times, initiated by caprolactamate-carbamoylcaprolactam initiating systems belong to green polymerization processes, leading to poly(ε-caprolactam) (Polyamide 6, PA6, Nylon 6). However, the effect of post-polymerization heat (i.e., slow, technically feasible cooling) on the fundamental characteristics of the resulting polymers such as yield and molecular weight distributions (MWDs) have not been revealed thus far. Significant post-polymerization effect was found by us in terms of both monomer conversions and MWDs by carrying out CPL polymerization with industrial components under conditions mimicking thermoplastic reaction transfer molding (T-RTM). Remarkably, higher monomer conversions and molecular weights (MWs) were obtained for Polyamide 6 samples prepared without quenching than that for the quenched polymers at the same reaction times. Independent of quenching or non-quenching, Mn of the resulting polymers as a function of conversion fell in the theoretical line of quasiliving AROP of CPL. At high monomer conversions, significant increase of the MW and broadening of the MWDs occurred, indicating pronounced chain–chain coupling. These findings have fundamental importance for designing processing conditions for in situ polymerization processes of ε-caprolactam by various techniques such as T-RTM, reaction injection molding (RIM), and other processing methods of Polyamide 6.

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Comerford, James W., Fergal P. Byrne, Simone Weinberger, Thomas J. Farmer, Georg M. Guebitz, Lucia Gardossi e Alessandro Pellis. "Thermal Upgrade of Enzymatically Synthesized Aliphatic and Aromatic Oligoesters". Materials 13, n.º 2 (13 de janeiro de 2020): 368. http://dx.doi.org/10.3390/ma13020368.

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The enzymatic synthesis of polyesters in solventless systems is an environmentally friendly and sustainable method for synthetizing bio-derived materials. Despite the greenness of the technique, in most cases only short oligoesters are obtained, with limited practical applications or requiring further chemical processing for their elongation. In this work, we present a catalyst-free thermal upgrade of enzymatically synthesized oligoesters. Different aliphatic and aromatic oligoesters were synthesized using immobilized Candida antarctica lipase B (iCaLB) as the catalyst (70 °C, 24 h) yielding poly(1,4-butylene adipate) (PBA, Mw = 2200), poly(1,4-butylene isophthalate) (PBI, Mw = 1000), poly(1,4-butylene 2,5-furandicarboxylate) (PBF, Mw = 600), and poly(1,4-butylene 2,4-pyridinedicarboxylate) (PBP, Mw = 1000). These polyesters were successfully thermally treated to obtain an increase in Mw of 8.5, 2.6, 3.3, and 2.7 folds, respectively. This investigation focused on the most successful upgrade, poly(1,4-butylene adipate), then discussed the possible effect of di-ester monomers as compared to di-acids in the thermally driven polycondensation. The herein-described two-step synthesis method represents a practical and cost-effective way to synthesize higher-molecular-weight polymers without the use of toxic metal catalysts such as titanium(IV) tert-butoxide, tin(II) 2-ethylhexanoate, and in particular, antimony(IV) oxide. At the same time, the method allows for the extension of the number of reuses of the biocatalyst by preventing its exposure to extreme denaturating conditions.

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Tuskaev, Vladislav, Svetlana Gagieva, Dmitrii Kurmaev, Nikolay Kolosov, Elena Mikhaylik, Evgenii Golubev, Alexander Sizov et al. "Titanium(III, IV)-Containing Catalytic Systems for Production of Ultrahigh Molecular Weight Polyethylene Nascent Reactor Powders, Suitable for Solventless Processing—Impact of Oxidation States of Transition Metal". Polymers 10, n.º 1 (21 de dezembro de 2017): 2. http://dx.doi.org/10.3390/polym10010002.

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Manning, Thelma G., Joseph Leone, Martijn Zebregs, Dinesh R. Ramlal e Chris A. van Driel. "Definition of a JA-2 Equivalent Propellant to be Produced by Continuous Solventless Extrusion". Journal of Applied Mechanics 80, n.º 3 (19 de abril de 2013). http://dx.doi.org/10.1115/1.4023315.

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In order to eliminate residual solvents in ammunition and to reduce the emissions of volatile organic compounds to the atmosphere, the U.S. Army ARDEC has teamed with TNO in developing a new process for the production of solventless propellant for tank ammunition. To reduce the costs of solventless propellants production, shear roll mill and continuous extrusion processing was investigated. As described in this paper JA-2 a double base propellant cannot be processed without solvent by the extrusion process. An alternative JA-2 equivalent propellant was defined. The aim of this work is to demonstrate the manufacturing of this propellant by solventless continuous twin screw extrusion processing while maintaining gun performance characteristics of conventional JA-2 propellant. This is elucidated by explicitly researching the relationship between interior ballistic properties of the gun propellant and utilizing a continuous manufacturing process. Processing conditions were established, and the propellant was manufactured accordingly. The extruded propellant has the desired properties, which resulted in a comparable gun performance as the conventional JA-2 propellant.

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Gikonyo, Ben, Fangbing Liu, Siddhartha De, Catherine Journet, Catherine Marichy e Alexandra Fateeva. "Investigating the vapour phase synthesis of copper terephthalate Metal Organic Framework thin films by atomic/molecular layer deposition". Dalton Transactions, 2022. http://dx.doi.org/10.1039/d2dt03216c.

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Solventless synthesis and processing of Metal Organic Frameworks (MOFs) is critical to implement these materials in applied technologies. Vapour phase synthesis of MOF thin films is particularly suitable for such...

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Lazarjani, Masoumeh Pourseyed, Owen Young, Lidya Kebede e Ali Seyfoddin. "Processing and extraction methods of medicinal cannabis: a narrative review". Journal of Cannabis Research 3, n.º 1 (19 de julho de 2021). http://dx.doi.org/10.1186/s42238-021-00087-9.

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Abstract Introduction As the cannabis industry transitions from a black market to a legal market, product development, and methods of extraction have become a focal point. To date, more than thousands of chemical constituents have been identified from the cannabis plant, all of which possess different chemical properties that require different conditions for preservation during drying and extraction. However, scientific publications that explore these areas for the cannabis plant are currently lacking. Method This is a narrative review paper which focuses on critiquing drying and extraction methods of Cannabis sativa L. plant. Relevant keywords such as medicinal cannabis, extraction, solvent, cannabinoids, and terpenes have been searched in PubMed, EMBASE, MEDLINE, Google Scholar, and Cochrane Library (Wiley) databases. Result To find relevant papers for this narrative review, 93 papers have been reviewed. Among them, 12 irrelevant papers were discarded. The excluded papers were either about hemp seed oil or hemp fiber and protein. Based on this review, solvent extraction is the most common method for cannabis plants. Although solventless and hydrodynamic extraction are known for their high yield and feasibility, more investigation is needed in these areas. Regarding the drying process, hang-drying is the most convenient method; however, it may be substituted by freeze-drying in the near future. Discussion This review analyses various drying and extraction processes to guide the selection of suitable methods for various types of cannabis products and applications. This is done by outlining traditional and modern methods of drying techniques, exploring the importance of solvents for extraction, visiting solventless extraction procedures, and finally comparing conventional and alternative methods of extraction. Conclusion In conclusion, based on the current knowledge, using organic solvents is the most convenient method for medicinal cannabis extraction. However, more research is needed for some of the drying and extraction methods. Also, developing a green and sustainable cannabis extraction method should be considered for future studies.

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"Towards Solventless Processing of Thick Electron-Beam (EB) Cured Lithium-Ion Battery Electrodes". ECS Meeting Abstracts, 2017. http://dx.doi.org/10.1149/ma2017-02/6/578.

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Rahimian, Kamyar, e Douglas A. Loy. "Solventless Sol-Gel Chemistry Through Ring-Opening Polymerization of Bridged Disilaoxacyclopentanes". MRS Proceedings 628 (2000). http://dx.doi.org/10.1557/proc-628-cc6.43.

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Ring-opening polymerization (ROP) of disilaoxacyclopentanes has proven to be an excellent approach to sol-gel type hybrid orgainc-inorganic materials [1]. These materials have shown promise as precursors for encapsulation and microelectronics applications (Figure 1). The polymers are highly crosslinked and are structurally similar to traditional sol-gels, but unlike typical sol-gels they are prepared by an organic base or Bronsted acid (formic or triflic acid), without the use of solvents and water, they have low VOC's and show little shrinkage during processing.

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Rahimian, Kamyar, e Douglas A. Loy. "Sol-Gel Chemistry by Ring-Opening Polymerization". MRS Proceedings 576 (1999). http://dx.doi.org/10.1557/proc-576-63.

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ABSTRACTSol-gel processing of materials is plagued by shrinkage during polymerization of the alkoxide monomers and processing (aging and drying) of the resulting gels. We have developed a new class of hybrid organic-inorganic materials based on the solventless ring-opening polymerization (ROP) of monomers bearing the 2,2,5,5-tetramethyl-2,5-disilaoxacyclopentyl group, which permits us to drastically reduce shrinkage in sol-gel processed materials. Because the monomers are polymerized through a chain growth mechanism catalyzed by base rather than the step growth mechanism normally used in sol-gel systems, hydrolysis and condensation products are entirely eliminated. Furthermore, since water is not required for hydrolysis, an alcohol solvent is not necessary. Monomers with two disilaoxacyclopentyl groups, separated by a rigid phenylene group or a more flexible alkylene group, were prepared through disilylation of the corresponding diacetylenes, followed by ring closure and hydrogenation. Anionic polymerization of these materials, either neat or with 2,2,5,5-tetramethyl-2,5-disila-1-oxacyclopentane as a copolymer, affords thermally stable transparent gels with no visible shrinkage. These materials provide an easy route to the introduction of sol-gel type materials in encapsulation of microelectronics, which we have successfully demonstrated.

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Ng, Kok Wei Joseph, Jacob Song Kiat Lim, Nupur Gupta, Bing Xue Dong, Chun-Po Hu, Jingdan Hu e Xiao Matthew Hu. "A facile alternative strategy of upcycling mixed plastic waste into vitrimers". Communications Chemistry 6, n.º 1 (27 de julho de 2023). http://dx.doi.org/10.1038/s42004-023-00949-8.

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AbstractChemical depolymerization has been identified as a promising approach towards recycling of plastic waste. However, complete depolymerization may be energy intensive with complications in purification. In this work, we have demonstrated upcycling of mixed plastic waste comprising a mixture of polyester, polyamide, and polyurethane through a reprocessable vitrimer of the depolymerized oligomers. Using poly(ethylene terephthalate) (PET) as a model polymer, we first demonstrated partial controlled depolymerization, using glycerol as a cleaving agent, to obtain branched PET oligomers. Recovered PET (RPET) oligomer was then used as a feedstock to produce a crosslinked yet reprocessable vitrimer (vRPET) despite having a wide molecular weight distribution using a solventless melt processing approach. Crosslinking and dynamic interactions were observed through rheology and dynamic mechanical analysis (DMA). Tensile mechanical studies showed no noticeable decrease in mechanical strength over multiple repeated melt processing cycles. Consequently, we have clearly demonstrated the applicability of the above method to upcycle mixed plastic wastes into vitrimers and reprocessable composites. This work also afforded insights into a potentially viable alternative route for utilization of depolymerized plastic/mixed plastic waste into crosslinked vitrimer resins manifesting excellent mechanical strength, while remaining reprocessable/ recyclable for cyclical lifetime use.

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Cheng, Chung‐Fu, Trevor J. McCraw, Theo H. Solomon, Michael R. Yan, Gary E. Wnek, Andrew Olah e Eric Baer. "High elastic modulus polyethylene: Process‐structure‐property relationships". SPE Polymers, 30 de março de 2024. http://dx.doi.org/10.1002/pls2.10130.

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AbstractPrevious studies have shown that gel‐spun‐ultra‐high‐molecular‐weight polyethylene (UHMWPE) produces thin fibril products that exhibit high tensile moduli (35–200 GPa). The elaborate gel‐spinning process involves complex drawing stages with solvent incorporation. In this study, a previously proposed two‐stage, environmentally friendly solventless methodology was optimized. The two‐stage process included cross‐rolling (Stage 1) and orientation (Stage 2) to obtain oriented HDPE thin rods with an impressively high modulus using conventional HDPE. The optimization of the process was successfully achieved by thoroughly investigating the voiding mechanism. In addition, rapid relaxation during orientation supports the cavitation mechanism. Owing to this optimization, a modulus of 75 GPa was readily attained. The significant enhancement in the mechanical properties was a direct result of the optimization of our processing methodology to achieve a high degree of orientation. Notably, the fabricated oriented HDPE thin rods showed moduli comparable to those of the gel‐spun UHMWPE fibers but were at least 40 times thicker. Our comprehensive characterization of the voiding process and stress relaxation during our two‐stage process indicated the formation of a highly taut network structure and craze‐like configuration with controlled delamination. Thus, our proposed hierarchical model was refined to elucidate the process‐structure‐property relationships in greater detail.Highlights An optimized two‐stage environmentally friendly solventless process has been developed to create oriented polyethylene thin rods with impressively high modulus (75 GPa). The optimization was achieved by thoroughly investigating the voiding effect during cross‐rolling and crystalline relaxation during orientation. Comparison of the modulus from our process are similar to various commercial, gel‐spun fibers. Our thin rod products are at least 40 times thicker than commercial gel‐spun fibers. The thin rod product has impressively high modulus‐to‐weight and strength‐to‐weight ratios for future study in composite systems.

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Artigos de revistas sobre o tema "Solventless processing"

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