Journal articles: 'Copolymers – Thermal properties'

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Eliza, Eliza, Desnelli Desnelli, Ady Mara, and Fahma Riyanti. "Study of Effect of Weight Ratio on Copolymerization of Chitosan and Acrylamide." Indonesian Journal of Fundamental and Applied Chemistry 6, no. 3 (October 20, 2020): 96–102. http://dx.doi.org/10.24845/ijfac.v6.i3.96.

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In this research, chitosan copolymer synthesis with acrylamide has been carried out by varying weight of chitosan and acrylamide, namely 2:3, 3:2 and 1:1 using a microwave oven. The copolymers characterization was carried out using FTIR, XRD, SEM and TGA/DTA. The results of the synthesis of chitosan copolymer with acrylamide were obtained the largest percentage of grafting at a ratio of 2:3. From the results of FTIR analysis showed that the copolymer had been successfully synthesized. XRD analysis showed that the copolymers synthesized have amorphous properties compared to chitosan. The results of SEM analysis, the copolymers had a porous structure. Thermal analysis showed that the copolymers have better thermal stability than chitosan. The swelling ability of the CA23 copolymer was higher than that of the CA32 and CA11 copolymers. The chitosan-acrylamide copolymer which was synthesized in a ratio of 2:3 has better properties

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Nevin Cankaya, Nevin Cankaya. "Grafting of Chitosan: Structural, Thermal and Antimicrobial Properties." Journal of the chemical society of pakistan 41, no. 2 (2019): 240. http://dx.doi.org/10.52568/000735/jcsp/41.02.2019.

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In this study, some new chitosan materials were synthesized by the grafting of chitosan with the monomers such as 1-vinylimidazole (VIM), methacrylamide (MAm) and 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS). First of all, chitosan methacrylate was prepared by esterification of primary -OH group with methacryloyl chloride a 25.13% yield by mole. The monomers were grafted into chitosan methacrylate via free radical polymerization using 2,2and#39;-Azobisisobutyronitrile as an initiator in N,N-dimethylformamide. The graft copolymers were characterized by FT-IR spectra and elemental analysis. Thermal stabilities of the graft copolymers were determined by TGA (thermo gravimetric analysis) method. The synthesized chitosan methacrylate and its graft copolymers were tested for their antimicrobial activity against bacteria and yeast.

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Barim, Gamze, and Mustafa Gokhun Yayla. "Copolymerization of 4-Acetylphenyl Methacrylate with Ethyl Methacrylate: Synthesis, Characterization, Monomer Reactivity Ratios, and Thermal Properties." International Journal of Polymer Science 2014 (2014): 1–10. http://dx.doi.org/10.1155/2014/643789.

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Methacrylates have high glass transition temperature (Tg) values and high thermal stability. A new methacrylate copolymer, poly(4-acetylphenyl methacrylate-co-ethyl methacrylate) (APMA-co-EMA), was synthesized. The thermal behaviors of copolymers were investigated by differential scanning calorimetry and thermogravimetric analysis. They behaved as new single polymers with singleTg’s and the thermal stability of the copolymers increased with increasing 4-acetylphenyl methacrylate (APMA) fraction, leading to the manufacture of copolymers with desiredTgvalues. Structure and composition of copolymers for a wide range of monomer feed ratios were determined by Fourier transform infrared (FT-IR) and1H-nuclear magnetic resonance (1H-NMR) spectroscopic techniques. Copolymerization reactions were continued up to 40% conversions. The monomer reactivity ratios for copolymer system were determined by the Kelen-Tüdös (ra(APMA)=0.81;rb(EMA)=0.61) and extended Kelen-Tüdös (ra=0.77;rb=0.54) methods and a nonlinear least squares (ra=0.74;rb=0.49) method.

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Li, Ru, Bao Tan Zhang, Bai Ling Liu, Xiu Ning Chen, and Gong Ying Wang. "Structure and Properties of Poly(Diphenylsiloxane-Co-Dimethylsiloxane) Modified MQ Silicone Resin." Advanced Materials Research 496 (March 2012): 109–15. http://dx.doi.org/10.4028/www.scientific.net/amr.496.109.

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A novel kind of poly(diphenylsiloxane-co-dimethylsiloxane)s modified MQ silicone resin were synthesised by the hydrolysis and condensation of diphenyldimethyloxysilane, dimethyldimethyloxy- silane, tetraethyloxysilane and hexamethyldisiloxane. The structure of the copolymers was confirmed by 1H and 29Si NMR. Their molecular weights were determined by GPC. Thermal transitions were characterized by DSC. In addition, the thermal stabilities were evaluated by TGA. Results indicated that the increasing content of phenyl mol% in copolymer enhances the optical and thermal properties of the copolymers. Moreover, it can be used as a potential vinyl terminated component in hydrosilylation materials in PSA and LED encapsulation.

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Nguyen, Thi Phuong Thu, Nadine Barroca-Aubry, Caroline Aymes-Chodur, Diana Dragoe, Gaëlle Pembouong, and Philippe Roger. "Copolymers Derived from Two Active Esters: Synthesis, Characterization, Thermal Properties, and Reactivity in Post-Modification." Molecules 27, no. 20 (October 12, 2022): 6827. http://dx.doi.org/10.3390/molecules27206827.

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Copolymers with two distinguished reactive repeating units are of great interest, as such copolymers might open the possibility of obtaining selective and/or consequent copolymers with different chemical structures and properties. In the present work, copolymers based on two active esters (pentafluorophenyl methacrylate and p-nitrophenyl methacrylate) with varied compositions were synthesized by Cu(0)-mediated reversible deactivation radical polymerization. This polymerization technique allows the preparation of copolymers with high to quantitative conversion of both comonomers, with moderate control over dispersity (Đ = 1.3–1.7). Additionally, by in-depth study on the composition of each copolymer by various techniques including elemental analysis, NMR, FT-IR, and XPS, it was possible to confirm the coherence between expected and obtained composition. Thermal analyses by DSC and TGA were implemented to investigate the relation between copolymers’ composition and their thermal properties. Finally, an evaluation of the difference in reactivity of the two monomer moieties was confirmed by post-modification of copolymers with a primary amine and a primary alcohol as the model.

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Sun, Yu, Yazhen Wang, Li Liu, and Tianyuan Xiao. "The Preparation, Thermal Properties, and Fire Property of a Phosphorus-Containing Flame-Retardant Styrene Copolymer." Materials 13, no. 1 (December 27, 2019): 127. http://dx.doi.org/10.3390/ma13010127.

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A 9,10-dihydro-9-oxa-10-phosphaphenanthrene 10-oxide (DOPO) acrylate, (6-oxidodibenzo [c,e][1,2] oxaphosphinin-6-yl) methyl acrylate (DOPOAA), has been prepared. Copolymers of styrene (St) and DOPOAA were prepared by emulsion polymerization. The chemical structures of copolymers containing levels of DOPOAA were verified using Fourier transform infrared (FT-IR) spectroscopy and 1H nuclear magnetic resonance (1H-NMR) spectroscopy. The thermal properties and flame-retardant behaviors of DOPO-containing monomers and copolymers were observed using thermogravimetric analysis and micro calorimetry tests. From thermogravimetric analysis (TGA), it was found out that the T5% for decomposition of the copolymer was lower than that of polystyrene (PS), but the residue at 700 °C was higher than that of PS. The results from micro calorimetry (MCC) tests indicated that the rate for the heat release of the copolymer combustion was lower than that for PS. The limiting oxygen index (LOI) for combustion of the copolymer rose with increasing levels of DOPOAA. These data indicate that copolymerization of the phosphorus-containing flame-retardant monomer, DOPOAA, into a PS segment can effectively improve the thermal stability and flame retardancy of the copolymer.

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Sidra, Lala Rukh, Nafeesa Mushtaq, Guofei Chen, and Xingzhong Fang. "Synthesis of high Tg and organosoluble poly(N-arylene benzimidazole ether imide) copolymers by C–N/C–O coupling reaction." High Performance Polymers 30, no. 4 (April 5, 2017): 465–74. http://dx.doi.org/10.1177/0954008317701822.

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A series of poly( N-arylene benzimidazole ether imide) copolymers PEIBIs were prepared from 1H,3′H-5,5′-bis-benzimidazole, bisphenol-A and 4,4′-bis(4-fluorophthalimido)diphenyl ether by nucleophilic displacement polymerization. The resulting copolymers PEIBI(10–90) demonstrated moderate to good solubility in polar aprotic solvents and high glass transition temperatures ( Tgs) of 228–336°C, good thermal stability with 10% weight loss temperatures in the range of 503–548°C. All copolymer films showed good mechanical properties with tensile strengths of 101–130 MPa, tensile moduli of 3.3–4.0 GPa, elongations at break of 5–7%, and also presented low water uptake (0.15–0.34%). The wide-angle X-ray diffraction results revealed the amorphous nature of copolymers. The copolymer PEIBI-80 showed good balance in solubility, thermal and mechanical properties.

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Pascual-Jose, B., Alireza Zare, Silvia De la Flor, José Antonio Reina, M. Giamberini, and A. Ribes-Greus. "Dielectric Properties in Oriented and Unoriented Membranes Based on Poly(Epichlorohydrin-co-Ethylene Oxide) Copolymers: Part III." Polymers 14, no. 7 (March 28, 2022): 1369. http://dx.doi.org/10.3390/polym14071369.

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The dielectric spectra and conductivity properties of neat poly(epichlorohydrin-co-ethylene oxide)(PECH-co-EO) copolymer and two modified copolymers with a 20% or 40% of dendron 3,4,5-tris[4-(n-dodecan-1-yloxy)benzyloxy] benzoate units were analysed. A process of thermal orientation was applied to the copolymers to fine-tune the molecular motion of the side chains and determine their validity for cation transport materials. The study was conducted using Dielectric Thermal Analysis (DETA). The spectra of the modified unoriented and oriented copolymers consisted of five dielectric relaxations (δ, γ, β, αTg, and αmelting). The analysis of the relaxations processes shows that as the grafting with the dendron units increases, both the lateral and main chains have a greater difficulty moving. The thermal orientation induces in the main chain partial crystallization, including the polyether segments, and modifies the cooperative motion of the main chain associated with the glass transition (αTg). A deep analysis of the electrical loss modulus revealed that the degree of modification only modifies the temperature peak of each relaxation, and this effect is more perceived if the dendron unit content is higher (40%). The thermal orientation process seems equal to the spectra of CP20-O and CP40-O to the point that the degree of modification does not matter. Nevertheless, the fragility index denotes the differences in the molecular motion between both copolymers (40% and 20%) due to the thermal orientation. The study of the electric conductivity showed that the ideal long-range pathways were being altered by neither the thermal orientation process nor the addition of dendrimers. The analysis of the through-plane proton conductivity confirmed that the oriented copolymer with the highest concentration of dendrimers was the best performer and the most suitable copolymer for proton transport materials.

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Naddeo, Marco, Andrea Sorrentino, and Daniela Pappalardo. "Thermo-Rheological and Shape Memory Properties of Block and Random Copolymers of Lactide and ε-Caprolactone." Polymers 13, no. 4 (February 19, 2021): 627. http://dx.doi.org/10.3390/polym13040627.

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Biodegradable block and random copolymers have attracted numerous research interests in different areas, due to their capability to provide a broad range of properties. In this paper, an efficient strategy has been reported for preparing biodegradable PCL-PLA copolymers with improved thermal, mechanical and rheological properties. Two block-copolymers are synthesized by sequential addition of the cyclic esters lactide (L-LA or D,L-LA) and ε-caprolactone (CL) in presence of a dimethyl(salicylaldiminato)aluminium compound. The random copolymer of L-LA and CL was synthetized by using the same catalyst. Chain structure, molar mass, thermal, rheological and mechanical properties are characterized by NMR, SEC, TGA, DSC, Rheometry and DMTA. Experimental results show that by changing the stereochemistry and monomer distribution of the copolymers it is possible to obtain a variety of properties. Promising shape-memory properties are also observed in the di-block copolymers characterized by the co-crystallization of CL and L-LA segments. These materials show great potential to substitute oil-based polymers for packaging, electronics, and medicine applications.

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Jubsilp, Chanchira, Sarawut Rimdusit, and Tsutomu Takeichi. "Effect of Rubber Contents on Tribological and Thermomechanical Properties of Polybenzoxazine." Applied Mechanics and Materials 576 (June 2014): 75–79. http://dx.doi.org/10.4028/www.scientific.net/amm.576.75.

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Bisphenol-A/aniline based polybenzoxazine (PBZ) modified with amine terminated butadiene–acrylonitrile (ATBN) were prepared. The tribological and thermomechanical properties as well as thermal stability of the PBZ/ATBN copolymers were investigated by ball-on-disc tribometer, dynamic mechanical analysis (DMA), universal test machine and thermogravimetric analysis (TGA). The inclusion of ATBN at a mass fraction of 5% was found to greatly increase friction coefficient and wear resistance of the copolymers. DMA measurements showed that the storage modulus and the glass transition temperature of the PBZ can be maintained with an addition of ATBN in the range of 1-5wt%. Moreover, flexural property measurements indicated that the flexural strength of the copolymer increased with increasing of ATBN content up to 10wt% whereas TGA results revealed that an increase of the PBZ content can help improve thermal stability of the copolymers.

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Romanko, O. I., and E. A. Eliseeva. "On the effect of the flexibility parameter on thermodynamic properties of acrylonitrile and methylvinylpyridine copolymers." Herald of the Bauman Moscow State Technical University. Series Natural Sciences, no. 1 (88) (February 2020): 71–79. http://dx.doi.org/10.18698/1812-3368-2020-1-71-79.

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We used thermal analysis to investigate the effects of temperature (20--300 °C) on the behaviour of acrylonitrile and methylvinylpyridine copolymers and determine the temperature ranges in which segmental mobility develops in them, as well as their glass transition temperatures. Data obtained via differential thermal analysis allowed us to compute activation energies for vitrification processes in copolymers of the series specified and to plot vitrification temperature as a function of copolymer composition. We used the method of increments to compute flexibility parameters for acrylonitrile and 2-methyl-5-vinylpyridine and analyse the effects of flexibility parameters on the manifestation of relaxation processes. The data obtained may be used to amend manufacturing parameters when developing chemisorptive filter materials based on the specified copolymer series.

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12

Nguyen, Thi Nhan, Hieu Nguyen Duy, Dung Tran Anh, Thuong Nghiem Thi, Thu Ha Nguyen, Nam Nguyen Van, Tung Tran Quang, Tung Nguyen Huy, and Thuy Tran Thi. "Improvement of Thermal and Mechanical Properties of Vietnam Deproteinized Natural Rubber via Graft Copolymerization with Methyl Methacrylate." International Journal of Polymer Science 2020 (July 14, 2020): 1–11. http://dx.doi.org/10.1155/2020/9037827.

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In this study, we investigated the improvement of the thermal and mechanical properties of Vietnam deproteinized natural rubber (DPNR) via graft copolymerization of methyl methacrylate (MMA). The graft copolymerization was achieved successfully in latex stage using tert-butyl hydroperoxide (TBHPO) and tetra-ethylenepentamine (TEPA) as radical initiators at 30°C. By grafting with various MMA feeds and initiator concentration of 6.6×10−5 mol/g-rubber, the highest grafting efficiency and conversion were achieved at MMA of 15 wt.% per kg of rubber, 68% and 90%, respectively. The structure of grafted copolymers was characterized by 1H NMR, FTIR-ATR, and GPC, and thermal properties were investigated through DSC and TGA measurements. These showed that graft copolymers were more stable and rigid than DPNR. Storage modulus (G′) of graft copolymer was found to double that of DPNR, which contributed to the formation of graft copolymer. After sulfur vulcanization, the mechanical properties of DPNR-graft-PMMA, such as tensile strength, tear strength, and hardness, were improved significantly. Curing behaviors of the graft copolymers were found to be remarkably better than virgin DPNR.

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Benavides, R., L. W. Oenning, M. M. S. Paula, L. Da Silva, and C. Kotzian. "Use of a TrI-functional Crosslinking Agent in Styrene/Acrylic Acid Copolymers to Enhance Mechanical Properties for use as Membranes in Fuel Cells." Journal of New Materials for Electrochemical Systems 16, no. 3 (July 4, 2013): 157–62. http://dx.doi.org/10.14447/jnmes.v16i3.5.

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Alternative copolymers to the well-known Nafion membranes are the styrene/acrylic acid PS/AA) copolymers, which have advantages in cost and availability of raw materials. Previous attempts to improve their mechanical properties involved crosslinking with divinyl benzene, but in this case the use of the tri-functional monomer TMPTMA (trimethylol propane trimethacrylate) is examined. Copolymers with a PS/AA molar ratio of 94/6 were prepared by a free radical polymerization reaction, including TMPTMA at 0.1, 0.01 and 0.001 % mol concentrations. Reactions were followed by percentage yield (gravimetry), Infrared spectroscopy (FTIR) and extent of crosslinking by gel percentage evaluation (soxhlet extraction) with three different solvents (water, tetrahydrofuran and dichloromethane). Thermal transitions were followed by calorimetry (DSC), stability by thermogravimetry (TGA) and mechanical properties by dynamic mechanical analysis (DMA). FTIR spectra show typical bands from the copolymer while the corresponding bands associated with crosslinking are overlapped; however, gel percentage evaluations show a higher level of crosslinking for the 0.1% TMPTMA copolymer and lack of solubility in water. DSC thermograms indicate an increment in the glass transition (Tg) and TGA exhibits a small increment in thermal stability for the crosslinked copolymers. Elastic moduli suggests a rubbery material for TMPTMA crosslinked copolymers while loss modulus confirms a Tg enhancement as observed by DSC. A 0.1 % TMPTMA copolymer does not form a membrane due to its insolubility and infusibility.

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Yao, Xin Ding, Rui Na Fang, Hong Jian Pang, Zong Wu Wang, and Guo Ji Liu. "Novel Copolymers of N-[(4-bromo-3,5- difluorine) phenyl] acryl- amide with Methyl Methacrylate: Synthesis, Characterization and Thermal Properties." Advanced Materials Research 750-752 (August 2013): 1125–29. http://dx.doi.org/10.4028/www.scientific.net/amr.750-752.1125.

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Copolymers of N-[(4-bromo-3,5-difluorine) phenyacrylamide (BDPA), with methyl methacrylate (MMA) were synthesized in N,N-Dimethylformamide at 75±1°C using 2,2-azobisisobutyronitrile (AIBN) as an initiator with different monomer-to-monomer ratios in the feed. The copolymers were characterized by FTIR and 1H NMR spectra. The glass transition temperature of the copolymers decreases with increase in BDPA content. The thermogravimetric analysis of the polymers showed that the thermal stability of the copolymer decreases with BDPA content.

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Nguyen, Thai Hien, Atitsa Petchsuk, Pramuan Tangboriboonrat, Mantana Opaprakasit, Alice Sharp, and Pakorn Opaprakasit. "Synthesis and Characterizations of PLLA/PEG Block Copolymers." Advanced Materials Research 93-94 (January 2010): 198–201. http://dx.doi.org/10.4028/www.scientific.net/amr.93-94.198.

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Poly(lactic acid-co-ethylene glycol) (PLLA/PEG) copolymers were synthesized and their properties were characterized. The PLLA/PEG/PLLA triblock copolymers were synthesized by ring-opening polymerization from l-lactide (LLA) and PEG macroinitiator. Stannous octoate, Sn(Oct)2 was used as a catalyst. Effects of molecular weight of PEG (600, 2000 and 4000), LLA/OH molar ratios (95:5, 98:2) and a sequence of addition of the reactants on properties of the copolymers were investigated. The triblock copolymers were subsequently used in a production of multiblock copolymers by reacting with a chain-extending agent, hexamethylene diisocyanate (HMDI). Chemical structure and molecular weight of the copolymers were characterized by 1H-NMR, FTIR and GPC. The results showed that molecular weight of triblock copolymers varied from 4,500 to 10,200. After chain extension, multiblock copolymer with molecular weight of 16,490 was produced. Thermal properties of the copolymers were also examined by DSC.

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Huang, Yih-Sheng, Sheng-Haur Yu, Yea-Ru Sheu, and Kuo-Shien Huang. "Preparation and Thermal and Anti-UV Properties of Chitosan/Mica Copolymer." Journal of Nanomaterials 2010 (2010): 1–6. http://dx.doi.org/10.1155/2010/513798.

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This experiment aims to produce a free radical while annoying the oxidizing-reducing reagent of the ammonium persulfate and the sodium bisulfite under nitrogen, then trigger copolymerization between modified-mica and chitosan to prepare a variety of copolymers. This experiment also aims to study the related properties of these copolymer materials. The experimental data shows that the copolymer has more thermal stability and better absorption of UV than chitosan. But the above physical properties will be less if the mica ratio in copolymer is more than 8%. On the other hand, the SEM photo of the microstructure also shows that the modified mica distributes homogeneously on the surface of the film of the copolymer.

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Tegegne, Newayemedhin A., Zelalem Abdissa, and Wendimagegn Mammo. "Photophysical, Thermal and Structural Properties of Thiophene and Benzodithiophene-Based Copolymers Synthesized by Direct Arylation Polycondensation Method." Polymers 13, no. 7 (April 4, 2021): 1151. http://dx.doi.org/10.3390/polym13071151.

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Three low-band-gap copolymers based on isoindigo acceptor units were designed and successfully synthesized by direct arylation polycondensation method. Two of them were benzodithiophene (BDT)-isoindigo copolymers (PBDTI-OD and PBDTI-DT) with 2-octlydodecyl (OD) and 2-decyltetradecyl (DT) substituted isoindigo units, respectively. Thiophene donor and DT-substituted isoindigo acceptor units were copolymerized to synthesize PTI-DT. The copolymers have a broad absorption range that extends to over 760 nm with a band gap ≈1.5 eV. The photophysical property studies showed that the BDT-based copolymers have non-polar ground states. Their emission exhibited the population of the intramolecular charge transfer (ICT) state in polar solvents and tightly bound excitonic state in non-polar solvents due to self-aggregation. On the contrary, the emission from the thiophene-based copolymers was only from the tightly bound excitonic state. The thermal decomposition temperature of the copolymers was above 380 °C. The X-ray diffraction pattern of the three copolymers showed a halo due to π−π stacking. A second, sharper peak was observed in the BDT-based copolymer with a longer side chain on the isoindigo unit (PBDTI-DT), and the thiophene-based copolymers with PTI-DT, exhibiting a better structural order.

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18

Groch, Paweł, Katarzyna Dziubek, Krystyna Czaja, and Beata Sacher-Majewska. "Thermal behavior of ethylene copolymers with di- and tri-alkenylsilsesquioxane comonomers synthesized by post-metallocene catalysts." Journal of Thermal Analysis and Calorimetry 142, no. 4 (March 4, 2020): 1447–56. http://dx.doi.org/10.1007/s10973-020-09491-4.

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Abstract This paper reported thermal properties of ethylene copolymers with di- and tri-alkenylsilsesquioxanes (POSS) synthesized by bis(phenoxy-imine) Ti, Zr, V, and V salen-type complexes. Ethylene copolymers with multi-alkenyl POSS obtained by such complexes contain multi-alkenyl POSS incorporated into the polymer chain as a side group. They were characterized by different thermal behavior depending on the kind of multi-alkenyl POSS comonomer, and type of the catalyst used, as well as polymerization conditions and thus the structure of the copolymer chain. Ethylene/POSS copolymers differed in incorporation of POSS into the polymer chain, content of specific unsaturation groups, and molecular weight, as well as heterogeneity of polymer chain compositions. The incorporation of multi-alkenyl POSS into the polymer chain affected melting and crystallization processes of copolymers in different ways. The POSS units could act as a nucleating agent of macromolecules. The increasing POSS content in E/POSS copolymers resulted in increasing thermal stability of obtained products, regardless of the kind of multi-alkenylsilsesquioxanes used. Thermal stability of such copolymers increased with decreasing content of trisubstituted vinylene groups (internal saturations) as well. The highest improvement of thermal stability over 85 °C in comparison with PE was observed in case of E/POSS copolymers synthesized by bis(phenoxy-imine) zirconium catalyst. The composition heterogeneity of E/POSS copolymers was found to affect markedly thermal stability of E/POSS copolymers.

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Khatiwada, Shankar P., Sabu Thomas, Jean Marc Saiter, Ralf Lach, and Rameshwar Adhikari. "Mechanical and thermal properties of triblock copolymer modified epoxy resins." BIBECHANA 16 (November 22, 2018): 196–203. http://dx.doi.org/10.3126/bibechana.v16i0.21651.

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We investigate the ways of improving thermal and mechanical properties of diglycidyl ether of bisphenol-A (DGEBA) based thermoset resin using diaminodiphenylsulphone (DDS) as hardener and using epoxidized polystyrene/polybutadiene-based triblock copolymers as modifier. The epoxidation was performed. The targeted chemical modification using meta-chloroperoxybenzoic acid (m-CPBA) of the copolymer was performed whereby the epoxidation of the butadiene chains mainly took place at 1,4 linkages. The modification copolymer was found to contribute in enhancing the mechanical performance of the blends with epoxy resin. The results indicated the formation of nanostructured morphology in the blends attributable to their enhanced impact strength.BIBECHANA 16 (2019) 196-203

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Xiao, Shengdong, and Jude O. Iroh. "Novel Polyimide-block-poly(dimethyl siloxane) copolymers: Effect of time on the synthesis and thermal properties." High Performance Polymers 34, no. 2 (October 14, 2021): 184–96. http://dx.doi.org/10.1177/09540083211040479.

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Polyimide-block-poly(dimethyl siloxane) copolymer was synthesized by a two-step process, initiated by coupling anhydride terminated poly(amic acid), AT-PAA with amino terminated poly(dimethyl siloxane), (NH2)2-PDMS to form poly(amic acid)-block-poly(dimethyl siloxane). The resulting copolymer is then thermally treated to produce polyimide-block-poly(dimethyl siloxane), PI-PDMS. Because of the high glass transition temperature, Tg of polyimide, it is usually cured at a high temperature of about 300°C for over 2.5 h. Copolymerization of polyimide with polysiloxane, reduces the imidization temperature while maintaining high thermomechanical properties. A series of instruments were used to monitor the progress of copolymerization. The time-based analysis of the product of copolymerization enables the optimization of the structure and properties of the copolymers. The chemical structure and composition of the copolymer were studied by Fourier Transform Infrared Spectroscopy, (FT-IR). The incorporation of PDMS blocks into the copolymer and the degree of imidization of the polyimide block increased with increasing reaction time. The change in the viscosity of the copolymerizing solution was monitored by simple shear viscometry conducted with the Brookfield Viscometer. The reported increase in solution viscosity with increasing copolymerization time is associated with increasing molecular weight of the copolymer. The intrinsic viscosity of the copolymer solution was measured as a function of copolymerization time and it was found that the intrinsic viscosity of the copolymer solution increased with increasing reaction time. The glass transition temperature (Tg) and the thermal stability of the copolymer were determined by differential scanning calorimetry, DSC and thermogravimetric analysis, and TGA, respectively. Between 25°C and 420°C, the copolymers synthesized in this study show two glass transition temperatures due to the polyimide, PI block at around 380°C and another peak associated with PDMS plasticized polyimide at about 290–300°C. The two Tg peaks observed in the DSC thermogram are believed to be indicative of the structure of a block copolymer. TGA analysis shows that the thermoxidative stability of the copolymers increased with increasing reaction time, due to the incorporation of increased amount of PDMS unit into the copolymer. The combination of increasing molecular weight of copolymer, higher degree of imidization of polyimide blocks and enhanced thermoxidative stability may translate into improved flame retardancy of copolymers. This suggested enhancement in flame retardancy in air atmosphere, is believed to be due the incorporated PDMS blocks, which can be converted into silica, SiO2, a recognized thermally stable material.

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Groch, Paweł, Anna Bihun-Kisiel, Aleksandra Piontek, and Wioletta Ochędzan-Siodłak. "Structural and Thermal Properties of Ethylene-Norbornene Copolymers Obtained Using Vanadium Homogeneous and SIL Catalysts." Polymers 12, no. 11 (October 22, 2020): 2433. http://dx.doi.org/10.3390/polym12112433.

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The series of ethylene-norbornene (E-NB) copolymers was obtained using different vanadium homogeneous and supported ionic liquid (SIL) catalyst systems. The 13C and 1H NMR (carbon and proton nuclear magnetic resonance spectroscopy) together with differential scanning calorimetry (DSC) were applied to determine the composition of copolymers such as comonomer incorporation (CNB), monomer dispersity (MD), monomer reactivity ratio (re), sequence length of ethylene (le) and tetrad microblock distributions. The relation between the type of catalyst, reaction conditions and on the other hand, the copolymer microstructure, chain termination reaction analyzed by the type of unsaturation are discussed. In addition, the thermal properties of E-NB copolymers such as the melting and crystallization behavior, like also the heterogeneity of composition described by successive the self-nucleation and annealing (SSA) and the dispersity index (DI) were determined.

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Park, Gi Tae, Won Jun Lee, Jin-Hae Chang, and Ae Ran Lim. "Dependence of the Physical Properties and Molecular Dynamics of Thermotropic Liquid Crystalline Copolyesters on p-Hydroxybenzoic Acid Content." Polymers 12, no. 1 (January 12, 2020): 198. http://dx.doi.org/10.3390/polym12010198.

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Two series of thermotropic liquid crystal copolymers (TLCPs) with different monomer structures and compositions were synthesized. The copolymers in the first series consisted of 2,5-diethoxyterephthalic acid (ETA), hydroquinone (HQ), and p-hydroxybenzoic acid (HBA), whereas those in the second series contained ETA, 2,7-dihydroxynaphthalene (DHN), and HBA. In both series, the molar ratio of HBA to the other monomers varied from 0 to 5. The thermal properties, degree of crystallinity, and stability of the liquid crystalline mesophase of the copolymers obtained at each HBA ratio were evaluated and compared. Overall, at each HBA content, the DHN-containing copolymer had better thermal properties, but the HQ-containing copolymer exhibited a higher degree of crystallinity and a more stable liquid crystalline mesophase. Furthermore, similar thermal stabilities were observed in both series. The dependence of the molecular dynamics of the TLCPs on the monomer structure was explained using 13C magic-angle spinning/cross-polarization nuclear magnetic resonance spectroscopy. An in-depth investigation of the relaxation time of each carbon revealed that the molecular motions of the TLCPs were greatly influenced by the structures of the monomers present in the main chain. The molecular dynamics of the HQ and DHN monomers in the two series were evaluated and compared.

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Song, Lixin, Qian Zhang, Yongsheng Hao, Yongchao Li, Weihan Chi, Fei Cong, Ying Shi, and Li-Zhi Liu. "Effect of Different Comonomers Added to Graft Copolymers on the Properties of PLA/PPC/PLA-g-GMA Blends." Polymers 14, no. 19 (September 29, 2022): 4088. http://dx.doi.org/10.3390/polym14194088.

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The melt-free radical grafting of glycidyl methacrylate (GMA) onto poly (lactic acid) (PLA) with styrene (St), α-methylstyrene (AMS), and epoxy resin (EP) as comonomers in a twin-screw extruder was used to prepare PLA-g-GMA graft copolymers. The prepared graft copolymers were then used as compatibilizers to prepare PLA/PPC/PLA-g-GMA blends by melt blending with PLA and polypropylene carbonate (PPC), respectively. The effects of different comonomers in the PLA-g-GMA graft copolymers on the thermal, rheological, optical, and mechanical properties and microstructure of the blends were studied. It was found that the grafting degree of PLA-g-GMA graft copolymers was increased to varying degrees after the introduction of comonomers in the PLA-g-GMA grafting reaction system. When St was used as the comonomer, the grafting degree of the PLA-g-GMA graft copolymer increased most significantly, from 0.8 to 1.6 phr. St as a comonomer also most improved the compatibility between PLA and PPC, and the haze of the blends was reduced while maintaining high transmittance. In addition, the PLA-g-GMA graft copolymer with the introduction of St as a comonomer significantly improved the impact toughness of the blends, while the thermal stability and tensile strength of the blends remained largely unchanged.

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Li, Rui, Cheng Zhou, Yang Chen, Huawei Zou, Mei Liang, and Yi Li. "Preparation, characterization, and properties of organic silicone intermediate-modified epoxy resin copolymers." High Performance Polymers 29, no. 1 (July 28, 2016): 36–45. http://dx.doi.org/10.1177/0954008315627375.

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In this work, a series of silicone-containing epoxy copolymers (E231) were synthesized through a condensation reaction between the Si-OCH3 of SY231 and the –OH of E51. The chemical structural determinations of the copolymer were carried out with the Fourier transform infrared spectroscopy, nuclear magnetic resonance (NMR), and an epoxy equivalent weight test. Besides, the grafting content of SY231 in E231 copolymers was determined by the proton (1H) NMR integration technique. The mechanical properties, thermal stabilities, and morphology of impact fractured surface of cured products were also investigated. The experimental results show that increased impact strength was observed for the cured E231 products, meanwhile the improvement of the impact strength was closely related to the content of silicone in copolymers. A smooth surface was observed on the neat epoxy specimen, while a rough surface was observed by scanning electron microscopic examination on the impact fractured surface of the cured E231 products. The data of TGA indicated that silicone exerted its thermal stability through thermal decomposition energy dissipation, acted as thermal insulation, and finally enhanced the solid residue at 800°C. Dynamic thermomechanical analysis tests displayed that the glass transition temperature of epoxy systems decreased slightly with the introduction of the flexible organosilicone.

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Deng, Wen Jian, Xu Pin Zhuang, Ke Tian Guan, and Bo Wen Cheng. "Structure and Thermal Properties of Cellulose Diacetate-Graft-Poly(lactic Acid) Copolymer." Advanced Materials Research 221 (March 2011): 85–89. http://dx.doi.org/10.4028/www.scientific.net/amr.221.85.

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To improve the thermal behavior of cellulose diacetate, cellulose diacetate-graft-poly(lactic acid) copolymers (CDA-g-PLAs) were synthesized by ring-opening polymerization of L-lactide using stannous octoate (Sn(Oct)2) as catalyst. The molecular structure of the copolymer was characterized by FT-IR and 1H-NMR and the thermal properties were investigated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TG-DTA). The results showed that the product was grafted copolymer of cellulose diacetate-graft-poly(lactic acid) with different side-chain structure. The thermal processing properties of CDA-g-PLAs are remarkably improved with melting temperature(Tm) about 140°C which lower than that of CDA and decomposition temperature (Td) higher than 260°C.

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Patel, Jayesh R., Dipan H. Sutaria, and Magan N. Patel. "Physicochemical study of complexation and ion-exchange properties of 2-hydroxy-4-ethoxypropiophenone—ethylene glycol polymer." High Performance Polymers 6, no. 2 (April 1994): 123–32. http://dx.doi.org/10.1177/095400839400600203.

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Copolymers (HEPP-EG) were synthesized by the condensation of 2-hydroxy-4-ethoxypropiophenone with ethylene glycol in presence of polyphosphoric acid as a catalyst. The copolymers were characterized by elemental analyses, IR spectra, viscosity and thermal studies. The number-average molecular weight (Mn) was measured by non-aqueous conductometric titration. The copolymer HEPP-EG-6 was complexed with metal ions, Cu2+, Ni2+, Co2, Mn2+ and Zn2+ and characterized. Chelation ion-exchange properties have been studied by employing the batch equilibration method.

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Tuichiyev, Sh, A. M. Kuznetsova, A. M. Mukhammadiyeva, D. Rashidov, and B. Khamidov. "Structure and thermal properties of copolymers." Polymer Science U.S.S.R. 31, no. 6 (January 1989): 1314–18. http://dx.doi.org/10.1016/0032-3950(89)90158-5.

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Mao, Hua, Yong You, Lifen Tong, Xiaohe Tang, Renbo Wei, and Xiaobo Liu. "Dielectric properties of poly(arylene ether nitrile ketone) copolymers." High Performance Polymers 31, no. 8 (November 5, 2018): 901–8. http://dx.doi.org/10.1177/0954008318808570.

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A series of poly(arylene ether nitrile ketone) (PENK) random copolymers are successfully synthesized by the nucleophilic aromatic substitution polymerization of 2,6-dichlorobenzonitrile, 4,4′-difluorobenzophenone with various bisphenol monomers (4,4′-biphenol, bisphenol A, phenolphthalein, and hydroquinone). Compared with poly(arylene ether ketone), the PENK copolymers possess better solubility in polar solvents such as N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, dimethylsulfoxide, and so on. Because of the different molecular structures, the PENK copolymers exhibit thermal properties with their glass transition temperature ( T g) in the range of 171–237°C and 5% weight loss temperature ( T d) ranging from 409°C to 554°C. Moreover, all polymers with an intrinsic viscosity of approximately 1 dL/g show excellent film-forming properties and outstanding mechanical strength higher than 85 MPa. The temperature dependence of the dielectric constant and dielectric loss of all derived copolymers is stable before their T g. The breakdown strength of the hydroquinone-derived PENK copolymer is as high as 253 kV/mm, resulting in an energy storage density of 1.00 J/cm3. These solvent processable PENK copolymers are potential dielectric candidates for high temperature applications.

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Wang, Fusong, Lei Zhang, Xiaoshan Zhang, Hechuan Li, and Shaopeng Wu. "Aging Mechanism and Rejuvenating Possibility of SBS Copolymers in Asphalt Binders." Polymers 12, no. 1 (January 4, 2020): 92. http://dx.doi.org/10.3390/polym12010092.

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The styrene–butadiene–styrene (SBS)-modified asphalt pavement has been in growing demand in the road construction field owing to its workable mechanical property and temperature durability. This paper prepared a penetrative rejuvenator (PR) with waste cooking oil (WCO) and emulsified asphalt, then applied PR on SBS copolymers to investigate its aging and rejuvenating effects in an asphalt binder. After a thin film oven test (TFOT) and ultraviolet (UV) aging of SBS copolymers, Fourier transform infrared (FTIR) spectra were used to analyse the aged copolymers’ chemical structure. Moreover, both aged and rejuvenated SBS copolymers were added into a fresh asphalt binder to get two kinds of modified asphalt binders, namely, MAAC (modified by aged copolymer) and MARC (modified by rejuvenated copolymer). Aiming to analyse the monomer effect of SBS copolymers in the asphalt binder, the rheological characteristic with dynamic shear rheometer (DSR), chemical structure with FTIR and physical properties with penetration, soft point and ductility tests were investigated using MAAC and MAAC samples. The results showed that rejuvenated SBS copolymer could improve MAAC’s viscoelasticity, but from FTIR spectral analysis, PR resulted in no chemical changes to SBS copolymers. A tough coat which made MAAC of higher stiffness was observed on the copolymer surface after thermal treatment. UV caused evidently negative effects on SBS copolymer because of accelerating oxidation by ozone, which brought about high possibility of cracks during servicing periods of asphalt pavement. In addition, MAAC was inferior in both rheological and physical properties, which reflected the significance and necessity in consideration of alleviating SBS copolymer aging in field.

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Jeon, Oju, Su Jin Song, Min Hyung Lee, Sang Woo Seo, Cha Yong Choi, and Byoung Soo Kim. "Synthesis and Characterization of Polyethylenimine-Graft-Poly(L-Lactide-Co-Glycolide) Block Copolymers for Gene Delivery." Key Engineering Materials 342-343 (July 2007): 521–24. http://dx.doi.org/10.4028/www.scientific.net/kem.342-343.521.

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Polyethylenimine-graft-poly(L-lactide-co-glycolide) (PEI-g-PLGA) block copolymers were prepared by a ring-opening polymerization of L-lactide and glycolide using PEI as a macroinitiator and stannous octoate as a catalyst in dimethylformamide at 100 °C. The molecular structure of the block copolymers was evaluated with 1H-NMR, and the molecular weight of the block copolymers was determined with gel permeation chromatography. The thermal properties were investigated using differential scanning calorimetery and thermogravimetric analysis. The zetapotential of the pDNA/copolymer complexes was evaluated with dynamic laser light scattering. Cytotoxicity and gene transfection efficiency of PEI-g-PLGA were tested in vitro using human embryonic kidney 293 cell culture. The pDNA/copolymer complexes (N/P = 10) showed a lower zeta-potential than pDNA/PEI25kDa complex, suggesting the lower toxicity of the pDNA/copolymer complexes. The copolymer composition was found to significantly affect the gene transfection efficiency of the pDNA/copolymer complexes. The copolymers with lower contents of PLGA showed higher gene transfection efficiency. These results indicate that these block copolymers are promising candidates for gene delivery vehicles, featuring good biocompatibility, potential biodegradability, and relatively high gene transfection efficiency.

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Wręczycki, Jakub, Dariusz Bieliński, and Rafał Anyszka. "Sulfur/Organic Copolymers as Curing Agents for Rubber." Polymers 10, no. 8 (August 5, 2018): 870. http://dx.doi.org/10.3390/polym10080870.

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It is widely acknowledged that waste sulfur generated from the petroleum industry creates huge storage and ecological problems. Therefore, the various methods of utilization are becoming increasingly attractive research topics worldwide. The thermal ability of elemental sulfur to homolytic cleavage of S8 rings enables its free radical copolymerization with unsaturated organic species and the obtaining of chemically stable polymeric materials. Here we report a novel possibility to use sulfur/organic copolymers obtained via “inverse vulcanization” as curatives for rubber. For this purpose, several various sulfur/organic copolymers were synthesized and analyzed from the point of view of their performance as rubber crosslinking agents. Solvent extraction was used to purify sulfur/organic copolymers from unreacted (elemental) sulfur. Thermal properties of the prepared copolymers were characterized by thermogravimetric analysis and differential scanning calorimetry (TGA–DSC). Crosslink density and structure of cured elastomers was studied by equilibrium swelling, thiol-amine analysis and freezing point depression. Mechanical properties of the vulcanizates were determined under static and dynamic conditions (DMA—dynamic mechanical analysis). It is proved that the utilization of sulfur/organic copolymers as curatives enables an effective crosslinking process of rubbers. Taking into account the results of a crosslink density analysis and mechanical properties of the vulcanizates cured with purified copolymers, it is evident that relatively long copolymer macromolecules are also involved in the formation of chemical bonds between unsaturated rubber macromolecules.

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Moura, Isabel, Ana Vera Machado, Regina Nogueira, and V. Bounor-Legare. "Synthesis of Biodegradable Copolymers Based on Ethylene Vinyl Acetate and Polylactic Acid." Materials Science Forum 636-637 (January 2010): 819–24. http://dx.doi.org/10.4028/www.scientific.net/msf.636-637.819.

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In the present study biodegradable copolymers of ethylene vinyl acetate and polylactic acid were synthesized using transesterification reactions, the structure, morphology, mechanical properties and biodegradability of the produced materials were characterized. Ethylene vinyl acetate was modified with polylactic acid in an internal mixer using titanium propoxide as transesterification catalyst. The graft copolymers were characterized by elemental analysis, infrared spectroscopy, rheology, scanning electron microscopy and thermal analysis. Selective extractions for all copolymers were made, and the results indicate that a maximum of 25 % of EVA-g-PLA copolymer was synthesized by this method. Biodegradation tests were carried out using the standard ISO 14851 (1999), which specifies a method for determining the biochemical oxygen demand in a closed respirometer. This procedure allowed to synthesize biodegradable copolymers with mechanical properties similar to conventional polymers.

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Xu, Qiu Shu, Lian Tang, Chao Sheng Wang, Biao Wang, and Hua Ping Wang. "Effects of Poly(Ethylene Glycol) Segment on Physical and Chemical Properties of Poly(Ether Ester) Elastomers." Materials Science Forum 898 (June 2017): 2147–57. http://dx.doi.org/10.4028/www.scientific.net/msf.898.2147.

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Poly (ether ester) elastomer, a segmented copolymer, recently has attracted a wide attention for its unique properties such as elasticity, low temperature impact resistance and chemistry resistance. In this work, a range of poly (ether ester) s were synthesized via a two-step polymerization method using poly (ethylene terephthalate) (PET) as rigid segment and poly (ethylene glycol) (PEG) as flexible segment. The effects of the molecular weight (1000-8000 g/mol) and the weight ratios with PEG (30/100-70/100) of PET segments on the performance of synthetic copolymers were investigated. The chemical structure, thermal properties and hydrophilic performance of the copolymers were respectively characterized. Additionally, the practical block ratios of PEG/PET were calculated by the 1H-NMR Spectra of the copolymer after Soxhlet extraction. Through the obtained results, it revealed that increasing the molecular weight or content of PEG could enhance the hydrophilic performance of the copolymers and reversely reduce its thermal stability. It was shown that the reactivity of PEG in the polymerization process was weakened when its molecular weight was above 4000 or weight ratio with PTA was higher than 60/100, subsequently affected the practical block ratios of PEG/PET in the resulting poly(ether ester)elastomers.

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Liang, Jing-Yu, Se-Ra Shin, Soo-Hyoung Lee, and Dai-Soo Lee. "Characteristics of Self-Healable Copolymers of Styrene and Eugenol Terminated Polyurethane Prepolymer." Polymers 11, no. 10 (October 14, 2019): 1674. http://dx.doi.org/10.3390/polym11101674.

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With limited biomass that can be currently utilized as a renewable resource, it is important to develop a method to convert biomass into materials that can replace fossil fuel product. In this paper, eugenol, a bio-based allyl chain-substituted guaiacol, was used to synthesize self-healable copolymers. Eugenol terminated polyurethane prepolymer (ETPU) was synthesized from eugenol and polyurethane prepolymers terminated with isocyanate groups. ETPU contained two allyl groups. Self-healing copolymer networks were obtained by copolymerization of ETPU and styrene monomer via free radical polymerization. Effects of ETPU content on the properties of copolymers were then studied. These copolymers containing ETPU exhibited good thermal stability and mechanical properties. These copolymers showed higher tensile strength and elongation at break than PS. Their maximum tensile strength reached 19 MPa. In addition, these copolymers showed self-healing property at elevated temperature due to the reversible nature of urethane units in ETPU.

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35

Guan, Xinghua, Xiaoyan Ma, Hualong Zhou, Fang Chen, and Zhiguang Li. "Synthesis and thermal decomposition kinetics of poly(methyl methacrylate)-b-poly(styrene) block copolymers." Journal of Thermoplastic Composite Materials 30, no. 5 (October 14, 2015): 691–706. http://dx.doi.org/10.1177/0892705715610406.

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Two diblock copolymers of poly(methyl methacrylate)- block-poly(styrene) with chlorine as terminal group (PMMA- b-PS-Cl) were synthesized via two-step atom transfer radical polymerization. The structures of the block copolymers were characterized by Fourier transform infrared spectroscopy, proton nuclear magnetic resonance, and gel permeation chromatography. Thermal properties including glass transition temperature ( Tg) and thermal stability were studied by differential scanning calorimetry and thermogravimetric analysis (TGA), respectively. The block copolymers of PMMA- b-PS-Cl exhibited two glass transitions, which were attributed to the Tgs of PMMA and PS segments, respectively. According to TGA, thermal decompositions of PMMA macro-initiator and PMMA- b-PS-Cl block copolymers had two stages. The weight loss ratio in the second stage was more significant than that in the first stage, which may be attributed to the separation of the halogen atom from the terminal group and the formation of a double bond. The breaking down of the backbone dominates in the second stage in which the weight loss ratio was more than 70%, represented the main stage of pyrolysis. It was found that the introduction of the PS chain remarkably enhanced the thermal stability of the copolymer, thus endowing the block copolymers high activation energy for thermal decomposition. On the other hand, the remaining two pyrolysis procedures further indicated that thermodynamic mechanism didn’t change due to the introduction of PS segments.

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Sen, Selda Sen. "Electrospun Nanofibers of Acrylonitrile and Itaconic Acid Copolymers and their Stabilization." JOURNAL OF ADVANCES IN CHEMISTRY 6, no. 2 (January 1, 2014): 958–81. http://dx.doi.org/10.24297/jac.v6i2.6575.

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(APS) as an oxidant in the aqueous medium,and nanofibers produced by electrospinning . Electrospun nanofiber mats were by treated heat under air atmosphere to be stabilized. Nanofiber production from AN-IA copolymers and suitability of the nanofiber as carbon nanofiber precursor is discussed. Copolymer are characterized using Fourier Transform Infrared - Attenuated Total Reflectance spectrometer (FTIR-ATR), Nuclear Magnetic Resonance Spectroscopy (1H-NMR), differential scanning calorimeter (DSC), thermal gravimetric analysis (TGA) and dynamic mechanical analysis (DMA). The effect of IA content on the spectroscopic and thermal properties of AN-IA copolymers was investigated. Increasing IA content confirmed by spectroscopic methods seriously affects thermal properties which is important for carbon nanofiber production. IA provides a catalytic effect on stabilization process by decreasing initiation cyclization reaction temperature from 202 to 195 oC. Elecrospinning from the AN-IA copolymer solutions in dimethyl foramide (DMF) was performed, morphology of nanofibers was monitored using Scanning Electron Microscopy (SEM). Bead free nanofibers were produced from AN-IA copolymer solutions under same conditions. Average nanofiber diameter decreases from 878±18 to 376±7 nm according to increasing IA content in copolymers. The nanofiber mats produced were treated at high temperature under air atmosphere for oxidative stabilization. Stabilized nanofibers were characterized using FTIR-ATR spectrometer and a new structure was monitored as a result of cyclization reactions. The stabilized nanofibers were also characterized mophologically using SEM. Volume loss occurring after heat treatment calculated based on the nanofiber diameter changes. Consequently, electrospun nanofibers can be suggested as a carbon nanofiber precursor due to suitability for electrospinning and stabilization process.

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Acikses, Aslisah, Gokce Taskan, and Gamze Barim. "A Study on Copolymer Systems of Styrene with Diethanolamine Side Group and Methyl Methacrylate." Journal of Chemistry 2018 (2018): 1–12. http://dx.doi.org/10.1155/2018/8957267.

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4-Diethanolaminomethyl styrene (DEAMSt) monomer was prepared by the modification of 4-chloromethyl styrene with diethanolamine. The copolymers in different combinations (0.11, 0.19, and 0.30 by mole) of DEAMSt and methyl methacrylate (MMA) were prepared by free radical polymerization method at 60°C in the presence of 1,4-dioxane and AIBN as initiator. The structures of DEAMSt and DEAMSt-MMA copolymer were characterized by FT-IR and 1H-NMR. The glass transition temperature (Tg) of the copolymers was measured by DSC. Thermal decomposition behavior of the copolymers was investigated by TGA. The average molecular weights of the copolymers were determined by GPC. The dye uptaking properties of the copolymers were investigated using bromocresol green. Then, the dielectric constant, dielectric loss factor, and conductivity of copolymers were investigated as a function of temperature and frequency. The activation energies (Ea) of the copolymers were determined by impedance analyzer.

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38

Nguyen, Van Hai, Thanh Danh Nguyen, Jongwoo Song, Jongdeok An, and Chan Im. "Influence of Block Ratio on Thermal, Optical, and Photovoltaic Properties of Poly(3-hexylthiophene)-b-poly(3-butylthiophene)-b-poly(3-octylthiophene)." Molecules 27, no. 23 (December 2, 2022): 8469. http://dx.doi.org/10.3390/molecules27238469.

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Efforts to improve the solar power conversion efficiencies of binary bulk heterojunction-type organic photovoltaic devices using an active layer consisting of a poly-(3-alkylthiophene) (P3AT) homopolymer and a suitable fullerene derivative face barriers caused by the intrinsic properties of homopolymers. To overcome such barriers, researchers might be able to chemically tailor homopolymers by means of monomer ratio-balanced block copolymerization to obtain preferable properties. Triblock copolymers consisting of three components—3-hexylthiophene (HT), 3-butylthiophene (BT), and 3-octylthiophene (OT)—were synthesized via Grignard metathesis (GRIM) polymerization. The component ratios of the synthesized block copolymers were virtually the same as the feeding ratios of the monomers, a fact which was verified using 1H-NMR spectra. All the copolymers exhibited comparable crystalline and melting temperatures, which increased when one type of monomer became dominant. In addition, their power conversion efficiencies and photoluminescence properties were governed by the major components of the copolymers. Interestingly, the HT component-dominated block copolymer indicated the highest power conversion efficiency, comparable to that of its homopolymer, although its molecular weight was significantly shorter.

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Pergal, Marija, Vesna Antic, Sanja Ostojic, Milena Marinovic-Cincovic, and Jasna Djonlagic. "Influence of the content of hard segments on the properties of novel urethane-siloxane copolymers based on a poly(ε-caprolactone)-b-poly(dimethylsiloxane)-b-poly(ε- caprolactone) triblock copolymer." Journal of the Serbian Chemical Society 76, no. 12 (2011): 1703–23. http://dx.doi.org/10.2298/jsc110307146p.

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A series of novel thermoplastic urethane-siloxane copolymers (TPUSs) based on a ?,?-dihydroxy-[poly(?-caprolactone)-bpoly( dimethylsiloxane)-b-poly(?-caprolactone)] (?,?-dihydroxy-PCLPDMS- PCL) triblock copolymer, 4,4?-methylenediphenyl diisocyanate (MDI) and 1,4-butanediol (BD) was synthesized. The effects of the content (9-63 wt. %) of hard urethane segments and their degree of polymerization on the properties of the segmented TPUSs were investigated. The structure, composition and hard segment degree of polymerization of the hard segments were examined using 1H- and quantitative 13C-NMR spectroscopy. The degree of crystallinity of the synthesized copolymers was determined using wide-angle X-ray scattering (WAXS). The surface properties were evaluated by measuring the water contact angle and water absorption. In the series of the TPUSs, the average degree of polymerization of the hard segments was varied from 1.2 to 14.4 MDI-BD units. It was found that average values from 3.8 to 14.4 MDI-BD units were effective segment lengths for crystallization of hard segments, which resulted in an increase in the degree of microphase separation of the copolymers. Spherulite-like superstructures were observed in copolymer films by scanning electron microscopy (SEM), which are believed to arise from the crystallization of the hard segments and/or PCL segments, depending on the content of the hard segments. The surface of the copolymers became more hydrophobic with increasing weight fraction of PDMS. The synthesized copolymers based on a PCL-PDMS-PCL segment showed good thermal stability, which increased with increasing content of soft PDMS segments, as was confirmed by the value of the starting temperature of thermal degradation.

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Oleszko-Torbus, Natalia, Barbara Mendrek, Agnieszka Kowalczuk, Alicja Utrata-Wesołek, Andrzej Dworak, and Wojciech Wałach. "Selective Partial Hydrolysis of 2-isopropyl-2-oxazoline Copolymers towards Decreasing the Ability to Crystallize." Materials 13, no. 15 (August 1, 2020): 3403. http://dx.doi.org/10.3390/ma13153403.

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Poly(2-isopropyl-2-oxazoline) (PiPrOx) is readily prone to crystallization both in solid and from solutions. This feature is detrimental for certain applications. Here, we examine whether the presence of unsubstituted ethyleneimine (EI) units, a gradient distributed within a polymer chain composed of 2-isopropyl-2-oxazoline (iPrOx) and 2-methyl-2-oxazoline (MOx) units, decreases the ability to crystallize the copolymer and affects thermal properties compared to the homopolymer of iPrOx. We assumed that the separation of stiff iPrOx units by the more flexible EI will affect the spatial arrangements of the ordered chains, slightly plasticize and, as a result, decrease their ability to crystallize. The selective hydrolysis of gradient iPrOx and 2-methyl-2-oxazoline (MOx) copolymers, carried out under mild conditions, led to iPrOx/MOx/EI copolymers. To the best of our knowledge, the selective hydrolysis of these copolymers has never been carried out before. Their thermal properties and crystallization abilities, both in a solid state and from an aqueous solution, were analyzed. Based on the analysis of polymer charge and cytotoxicity studies, the potential use of the copolymers obtained was indicated in some biological systems.

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Cheng, Jin, Shinji Kanehashi, and Kenji Ogino. "Synthesis and electron transporting properties of triblock copolymers consisting of polyfluorene and polystyrene." Japanese Journal of Applied Physics 61, SE (April 1, 2022): SE1008. http://dx.doi.org/10.35848/1347-4065/ac4c6b.

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Abstract For the improvement of the electron transporting property of poly(9,9-di-n-octylfluorene) (PFO) as a conventional polymer light-emitting diode material, well-defined triblock copolymers of PFO [number-average molecular weight (M n) ≈ 10 000] with different chain length polystyrene (PSt) (M n ≈ 1000, 2000, and 3000) were synthesized via a combined synthesis strategy of Suzuki–Miyaura reaction, atom transfer radical polymerization, and Steglich coupling reaction. Electron-only devices for homopolymer and triblock copolymers were fabricated by a solution process. It was demonstrated that triblock copolymer (M n,PSt ≈ 2000) after annealing exhibited the highest electron mobility. Thermal, optical, electrochemical and morphological properties were investigated severally and revealed that the microphase separated structure was formed in block copolymers (M n,PSt ≈ 2000, and 3000) after annealing, and the introduction of PSt raised the glass transition temperature (T g) and deepened the lowest unoccupied molecular orbital level.

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Thanomsilp, C., and U. Phetthianchai. "Synthesis and Characterisation of PLA-CO-PEG Copolymers." Advanced Materials Research 506 (April 2012): 178–81. http://dx.doi.org/10.4028/www.scientific.net/amr.506.178.

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PLA-co-PEG copolymers synthesized through ring opening polymerization between a lactide monomer and PEG were solution-cast into films. The effect of the molecular weight of PEG and also the percentage of added PEG on the properties of the copolymers were studied. The molecular weight of PEG was 4000, 8000, and 20000 while the percentage of added PEG was varied from 10 to 50 mol%. The NMR spectrums confirmed that the ratio of PLA:PEG in the copolymers are close to the monomer feed of the respective monomers. DSC and TGA results showed that, compared to PLA, the PLA-co-PEG copolymers have slightly lower melting temperatures but similar thermal degradation temperatures. Both molecular weights and the percentage added of PEG influenced the properties of the films. As expected, the tensile strength and Youngs modulus of the PLA-co-PEG copolymer films were lower than that of neat PLA. Conversely, theelongation at break of the copolymer film was higher than that of the PLA when the molecular weight of PEG was 20000. This study suggests that high molecular weight PEG could be used to improve the flexibility of the polymer films.

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Mohammed, Ameen Hadi, Tamador Ali Mahmood, Selvana Adwar Yousif, Aminu Musa, and Nerodh Nasser Dally. "Synthesis, Characterization and Reactivity Ratios of Poly Phenyl Acrylamide-Co-Methyl Methacrylate." Materials Science Forum 1002 (July 2020): 66–74. http://dx.doi.org/10.4028/www.scientific.net/msf.1002.66.

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The monomer phenyl acrylamide was synthesized by reacting acrylamide with chloro benzene in the presence of pyridine. Copolymer of phenyl acrylamide (PAM) with methyl methacrylate (MMA) was synthesized by free radical technique using dimethylsulfoxide (DMSO) as solvent and benzoyl peroxide (BPO) as initiator. The overall conversion was kept low (≤ 15% wt/wt) for all studies copolymers samples. The synthesized copolymers were characterized using fourier transform infrared spectroscopy (FT-IR), and their thermal properties were studied by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The copolymers compositions were determined by elemental analysis. The monomer reactivity ratios have been calculated by linearization methods proposed by Kelen-Tudos and Fineman-Ross. The derived reactivity ratios (r1, r2) for (PAM-co-MMA) are: (0.03, 0.593). The microstructure of copolymers and sequence distribution of monomers in the copolymers were calculated by statistical method based on the average reactivity ratios and found that these values are in agreement with the derived reactivity ratios. Copolymers of PAM with MMA formed alternating copolymers.

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Zaharescu, T., V. Meltzer, and R. Vilcu. "Thermal properties of irradiated ethylene-propylene copolymers." Journal of Materials Science Letters 15, no. 14 (1996): 1212–15. http://dx.doi.org/10.1007/bf00274378.

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Pielichowski, J., R. Chrzaszcz, E. Trebacz, and A. Wolff. "Thermal properties of methylmethacrylate-N-vinylcarbazole copolymers." Thermochimica Acta 94, no. 2 (October 1985): 367–78. http://dx.doi.org/10.1016/0040-6031(85)85280-1.

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Boufflet, Pierre, Sebastian Wood, Jessica Wade, Zhuping Fei, Ji-Seon Kim, and Martin Heeney. "Comparing blends and blocks: Synthesis of partially fluorinated diblock polythiophene copolymers to investigate the thermal stability of optical and morphological properties." Beilstein Journal of Organic Chemistry 12 (October 10, 2016): 2150–63. http://dx.doi.org/10.3762/bjoc.12.205.

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The microstructure of the active blend layer has been shown to be a critically important factor in the performance of organic solar devices. Block copolymers provide a potentially interesting avenue for controlling this active layer microstructure in solar cell blends. Here we explore the impact of backbone fluorination in block copolymers of poly(3-octyl-4-fluorothiophene)s and poly(3-octylthiophene) (F-P3OT-b-P3OT). Two block co-polymers with varying block lengths were prepared via sequential monomer addition under Kumada catalyst transfer polymerisation (KCTP) conditions. We compare the behavior of the block copolymer to that of the corresponding homopolymer blends. In both types of system, we find the fluorinated segments tend to dominate the UV–visible absorption and molecular vibrational spectral features, as well as the thermal behavior. In the block copolymer case, non-fluorinated segments appear to slightly frustrate the aggregation of the more fluorinated block. However, in situ temperature dependent Raman spectroscopy shows that the intramolecular order is more thermally stable in the block copolymer than in the corresponding blend, suggesting that such materials may be interesting for enhanced thermal stability of organic photovoltaic active layers based on similar systems.

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Nakan, Ulantay, Shayahati Bieerkehazhi, Balgyn Tolkyn, Grigoriy A. Mun, Mukhit Assanov, Merey E. Nursultanov, Raikhan K. Rakhmetullayeva, Kainaubek Toshtay, El-Sayed Negim, and Alibek Ydyrys. "Synthesis, Characterization and Antibacterial Application of Copolymers Based on N,N-Dimethyl Acrylamide and Acrylic Acid." Materials 14, no. 20 (October 18, 2021): 6191. http://dx.doi.org/10.3390/ma14206191.

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Hydrogel copolymers based on N,N-dimethyl acrylamide (DMA) and acrylic acid (AAc) were synthesized using a solution polymerization technique with different monomer ratios and ammonium persulfate as an initiator. This paper investigates the thermal stability, physical and chemical properties of the hydrogel copolymer. Testing includes Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and elemental analysis (CHNS). The copolymer composition was determined by elemental analysis, and the reactivity ratios of monomers were calculated through linearization methods such as Fineman–Ross (FR), inverted Fineman–Ross (IFR), Kelen–Tudos (KT) and Mayo–Lewis (ML). Good agreement was observed between the results of all four methods. The ratio of r1 and r2 were 0.38 (r1) and 1.45 (r2) (FR), 0.38 (r1) and 1.46 (r2) (IFR), 0.38 (r1) and 1.43 (r2) (KT), and 0.38 (r1) and 1.45 (r2) (ML). Hydrogel copolymers exhibited good thermal stability, and SEM showed three-dimensional porous structures. Antibiotic-free and antibiotic-loaded hydrogels demonstrated antimicrobial properties against both Gram-positive and Gram-negative bacteria. As the ratio of DMA in hydrogel copolymer increased, the activity of copolymer against bacteria enhanced. The results indicated that these hydrogels have the potential to be used as antibacterial materials.

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Behera, Girish Ch, Animesh Saha, and S. Ramakrishnan. "Hyperbranched Copolymers versus Linear Copolymers: A Comparative Study of Thermal Properties." Macromolecules 38, no. 18 (September 2005): 7695–701. http://dx.doi.org/10.1021/ma0508146.

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Al-Odayni, Abdel-Basit, Waseem Sharaf Saeed, Ahmed Yacine Badjah Hadj Ahmed, Ali Alrahlah, Abdullah Al-Kahtani, and Taieb Aouak. "New Monomer Based on Eugenol Methacrylate, Synthesis, Polymerization and Copolymerization with Methyl Methacrylate–Characterization and Thermal Properties." Polymers 12, no. 1 (January 8, 2020): 160. http://dx.doi.org/10.3390/polym12010160.

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Poly(eugenyl-2-hydroxypropyl methacrylate) (PEUGMA), poly(methyl methacrylate) (PMMA) and poly(eugenyl-2-hydroxypropyl methacrylate-co-methyl methacrylate) (PEUGMA-co-MMA) were synthesized by a free radical polymerization route in the presence of azobisisobutyronitrile. EUGMA was synthesized by etherification of the eugenol phenolic hydroxyl group with glycidyl methacrylate. Polymers and copolymers were characterized using size exclusion chromatography, Fourier transform infrared, and nuclear magnetic resonance. The effects of the encumbering substituent on the thermal behavior of the polymers and copolymers were studied by differential scanning calorimetry, thermogravimetry (TG) and direct analysis, using real-time, time-of-flight mass spectroscopy (DART-ToF-MS) methods. The results obtained revealed that for PEUGMA, the average molecular weight was 1.08 × 105, and increased slowly with the decrease in the EUGMA content in the copolymer. The order of the distribution of dyads comonomer units in the copolymer chains estimated by the Igarashi method based on the reactivity ratio does reveal a random distribution with a tendency toward alternation. The glass transition temperature of PEUGMA (46 °C) increased with the MMA content in the copolymer, and those of the copolymer fit well with the Johnston’s linearized expression. The TG analysis of pure PEUGMA revealed a significantly high thermal stability compared to that of PMMA. During its degradation, the preliminary decomposition was at 340 °C, and decreased as the MMA units increased in the copolymer. The DART-ToF-MS analysis revealed that the isothermal decomposition of PEUGMA led to a regeneration of raw materials such as EUGMA, GMA and EUG, in which the maximum amount was achieved at 450 °C.

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Cerrada, M. L., R. Benavente, and E. Pérez. "Influence of thermal history on morphology and viscoelastic behavior of ethylene–1-octene copolymers synthesized with metallocene catalysts." Journal of Materials Research 16, no. 4 (April 2001): 1103–11. http://dx.doi.org/10.1557/jmr.2001.0153.

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The relationships among structure and properties have been established in copolymers of ethylene and 1-octene, synthesized by a particular metallocene catalyst system. The most important factor affecting the structure and properties of these copolymers is, evidently, the comonomer content. However, the cooling treatment from the melt has been found to be also a very significant factor and, although its influence on the thermal properties is rather small, some structural parameters and the viscoelastic behavior are clearly dependent upon thermal history. These parameters include the degree of crystallinity, lattice constants, relaxation processes, stiffness, and microhardness of the samples. Regarding the viscoelastic behavior, the β relaxation is shifted to lower temperatures and its intensity is increased as 1-octene content raises. On the other hand, the α mechanism, associated with motions within the crystalline regions, is also moved to lower temperatures. Such a relaxation is only observed up to a certain 1-octene content in the copolymer.

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Journal articles on the topic 'Copolymers – Thermal properties'

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