scholarly journals Thermally Remendable Polyurethane Network Cross-Linked via Reversible Diels–Alder Reaction

Polymers ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 1935
Author(s):  
Elena Platonova ◽  
Islam Chechenov ◽  
Alexander Pavlov ◽  
Vitaliy Solodilov ◽  
Egor Afanasyev ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Differential Scanning Calorimetry ◽  
Nmr Spectroscopy ◽  
Young Modulus ◽  
Alder Reaction ◽  
Significant Loss ◽  
Diels Alder ◽  
Scanning Calorimetry ◽  
Diels Alder Reaction

We prepared a series of thermally remendable and recyclable polyurethanes crosslinked via reversible furan-maleimide Diels–Alder reaction based on TDI end-caped branched Voranol 3138 terminated with difurfurylamine and 4,4′-bis(maleimido)diphenylmethane (BMI). We showed that Young modulus strongly depends on BMI content (from 8 to 250 MPa) that allows us to obtain materials of different elasticity as simple as varying BMI content. The ability of DA and retro-DA reactions between furan and maleimide to reversibly bind material components was investigated by NMR spectroscopy, differential scanning calorimetry, and recycle testing. All polymers obtained demonstrated high strengths and could be recovering without significant loss in mechanical properties for at least five reprocessing cycles.

scholarly journals Rheometer Evidences for the Co-Curing Effect of a Bismaleimide in Conjunction with the Accelerated Sulfur on Natural Rubber/Chloroprene Rubber Blends

Polymers ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1510
Author(s):  
Marek Pöschl ◽  
Shibulal Gopi Sathi ◽  
Radek Stoček ◽  
Ondřej Kratina
Keyword(s):  
Mechanical Properties ◽  
Natural Rubber ◽  
Tensile Properties ◽  
Crosslinking Agent ◽  
Alder Reaction ◽  
Diels Alder ◽  
Ene Reactions ◽  
Rubber Blends ◽  
Diels Alder Reaction ◽  
Chloroprene Rubber

The rheometer curing curves of neat natural rubber (NR) and neat chloroprene rubber (CR) with maleide F (MF) exhibit considerable crosslinking torque at 180 °C. This indicates that MF can crosslink both these rubbers via Alder-ene reactions. Based on this knowledge, MF has been introduced as a co-crosslinking agent for a 50/50 blend of NR and CR in conjunction with accelerated sulfur. The delta (Δ) torque obtained from the curing curves of a blend with the addition of 1 phr MF was around 62% higher than those without MF. As the content of MF increased to 3 phr, the Δ torque was further raised to 236%. Moreover, the mechanical properties, particularly the tensile strength of the blend with the addition of 1 phr MF in conjunction with the accelerated sulfur, was around 201% higher than the blend without MF. The overall tensile properties of the blends cured with MF were almost retained even after ageing the samples at 70 °C for 72 h. This significant improvement in the curing torque and the tensile properties of the blends indicates that MF can co-crosslink between NR and CR via the Diels–Alder reaction.

3D printed remendable polylactic acid blends with uniform mechanical strength enabled by a dynamic Diels–Alder reaction

2017 ◽  
Vol 8 (13) ◽  
pp. 2087-2092 ◽  
Author(s):  
Gayan A. Appuhamillage ◽  
John C. Reagan ◽  
Sina Khorsandi ◽  
Joshua R. Davidson ◽  
Walter Voit ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Mechanical Strength ◽  
Polymer Blends ◽  
Polylactic Acid ◽  
Alder Reaction ◽  
Diels Alder ◽  
Diels Alder Reaction ◽  
3D Printed

We demonstrate that uniform mechanical properties can be achieved in 3D printed polymer blends by using a dynamic Diels–Alder reaction.

scholarly journals Influence of the Glass Transition Temperature and the Density of Crosslinking Groups on the Reversibility of Diels-Alder Polymer Networks

Polymers ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1189
Author(s):  
Merlina Thiessen ◽  
Volker Abetz
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Radical Polymerization ◽  
Polymer Networks ◽  
Alder Reaction ◽  
Diels Alder ◽  
Self Healing ◽  
Scanning Calorimetry ◽  
Diels Alder Reaction

The interest in self-healing, recyclable, and adaptable polymers is growing. This work addresses the reversibility of crosslink formation based on Diels-Alder reaction in copolymer networks containing furfuryl and maleimide groups, which represent the “diene” and the “dienophile,” respectively. The copolymers are synthesized by atom transfer radical polymerization (ATRP) and free radical polymerization. The diene bearing copolymers are crosslinked either with a small molecule containing two dienophiles or with a dienophile bearing copolymer. The influence of the crosslinking temperature on the Diels-Alder reaction is analyzed. Furthermore, the influence of the glass transition temperature and the influence of the density of crosslinking groups on the thermo-reversibility of crosslinking are investigated by temperature dependent infrared spectroscopy and differential scanning calorimetry. It is shown that the reversibility of crosslinking is strongly influenced by the glass transition temperature of the system.

Enantioselective Diels-Alder reaction of (E)-1-trimethylsilyloxy-1,3-butadiene with chiral glyoxylates

1990 ◽  
Vol 55 (1) ◽  
pp. 230-244 ◽  
Author(s):  
Otakar Červinka ◽  
Aleš Svatoš ◽  
Petr Trška ◽  
Pavel Pech
Keyword(s):  
Nmr Spectroscopy ◽  
Quantum Chemical Calculations ◽  
Absolute Configuration ◽  
Quantum Chemical ◽  
Alder Reaction ◽  
Diels Alder ◽  
Diels Alder Reaction ◽  
Chemical Correlation ◽  
The Absolute ◽  
C Nmr

Enantioselective Diels-Alder reaction of (E)-1-trimethylsilyloxy-1,3-butadiene (I) with chiral (-)-menthyl (II) and (-)-8-phenylmenthyl (III) glyoxylates in various solvents without or with catalysts was studied. The reactions gave a mixture of trans-and cis-isomers of (-)-menthyl (IV) and (-)-8-phenylmenthyl (V) 2-trimethylsilyloxy-5,6-dihydro-2H-pyran-6-carboxylates. The regioselectivity of the reaction was explained by quantum-chemical calculations, the enantioselectivity was determined using 13C NMR spectroscopy and the absolute configuration of the addition products was assigned on the basis of chemical correlation with (S)-(-)-dimethyl malate.

scholarly journals Thermally Self-Healing Graphene-Nanoplate/Polyurethane Nanocomposites via Diels–Alder Reaction through a One-Shot Process

Nanomaterials ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 434 ◽  
Author(s):  
Cho-Rong Oh ◽  
Sang-Hyub Lee ◽  
Jun-Hong Park ◽  
Dai-Soo Lee
Keyword(s):  
Molecular Design ◽  
Alder Reaction ◽  
Chain Extender ◽  
Diels Alder ◽  
Self Healing ◽  
Scanning Calorimetry ◽  
Diels Alder Reaction ◽  
A Chain ◽  
The Fourier Transform

Thermally self-healing graphene-nanoplate/polyurethane (GNP/PU) nanocomposites were prepared via a bulk in-situ Diels–Alder (DA) reaction. Graphene-nanoplate (GNP) was used as a reinforcement and crosslinking platform by a DA reaction with a furfuryl-based chain extender of polyurethane (PU). Results showed that a DA reaction occurred in GNP during the PU forming cure process. This procedure is simple and solvent free because of the absence of any independent surface modification process. Through the calculation of the interfacial tensions, the conditions of the bulk in-situ DA reaction were determined to ensure that GNP and the furfuryl group can react with each other at the interface during the curing process without a solvent. The prepared composites were characterized in terms of thermal, mechanical, and thermally self-healing properties via the DA reaction. In the PU capable of a DA reaction (DPU), characteristic peaks of DA and retro DA reactions were observed in the Fourier transform infrared (FT-IR) spectroscopy and endothermic peaks of retro DA reactions appeared in differential scanning calorimetry (DSC) thermograms. The DPU showed significantly enhanced physical properties and chemical resistance. The thermally self-healing capability was confirmed at 110 °C via the retro DA reactions. It is inferred that thermally self-healable crosslinked GNP/PU nanocomposites via DA reactions could be prepared in a simple bulk process through the molecular design of a chain extender for the in-situ reaction at the interface.

scholarly journals Production of a PET//LDPE Laminate Using a Reversibly Crosslinking Packaging Adhesive and Recycling in a Small-Scale Technical Plant

Recycling ◽  
2021 ◽  
Vol 6 (3) ◽  
pp. 47
Author(s):  
Katharina M. A. Kaiser ◽  
Tanja Ginzinger
Keyword(s):  
Molecular Weight ◽  
Pilot Plant ◽  
Alder Reaction ◽  
Diels Alder ◽  
Infrared Spectrometry ◽  
Small Scale ◽  
Scanning Calorimetry ◽  
Melt Index ◽  
Diels Alder Reaction ◽  
Pilot Plant Scale

Multilayer packaging is an important part of the packaging market, but it is not recyclable with conventional methods since it is made of different thermodynamically immiscible materials. In this work, it was shown that it is possible to produce a PET//LDPE laminate in a pilot plant for lamination by using an adhesive consisting of maleimide- and furan-functionalized polyurethane prepolymers that cure through the Diels–Alder reaction. The material could then be delaminated in a small-scale recycling plant using a solvent-based recycling process by partially opening the Diels–Alder adducts through the influence of temperature. The PET and LDPE could be recovered without any adhesive residues before each material was regranulated, and in the case of the PE, a film was produced via cast film extrusion. The obtained PET granulate exhibited a slight, approximately 10%, decrease in molecular weight. However, since small amounts of LDPE could not be separated, compatibilization would still be required here for further use of the material. The obtained LDPE film was characterized by means of infrared spectrometry, differential scanning calorimetry, tensile testing, determination of the melt index, and molecular weight. The film showed lower crosslinking than usual for LDPE recycling and exhibited good mechanical properties. In this work, it was thus shown that upscaling of the laminate production with the modified adhesive and also its recycling at the pilot plant scale is possible and thus could be an actual option for recycling multilayer packaging.

scholarly journals Improvement of Mechanical and Self-Healing Properties for Polymethacrylate Derivatives Containing Maleimide Modified Graphene Oxide

Polymers ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 603 ◽  
Author(s):  
Won-Ji Lee ◽  
Sang-Ho Cha
Keyword(s):  
Mechanical Properties ◽  
Graphene Oxide ◽  
Alder Reaction ◽  
Diels Alder ◽  
The Self ◽  
Self Healing ◽  
Diels Alder Reaction ◽  
Healing Efficiency ◽  
Modified Graphene Oxide ◽  
Modified Graphene

In this paper, a self-healable nanocomposite based on the Diels-Alder reaction is developed. A graphene-based nanofiller is introduced to improve the self-healing efficiency, as well as the mechanical properties of the nanocomposite. Graphene oxide (GO) is modified with maleimide functional groups, and the maleimide-modified GO (mGO) enhanced the compatibility of the polymer matrix and nanofiller. The tensile strength of the nanocomposite containing 0.030 wt% mGO is improved by 172%, compared to that of a polymer film incorporating both furan-functionalized polymer and bismaleimide without any nanofiller. Moreover, maleimide groups of the surface on mGO participate in the Diels-Alder reaction, which improves the self-healing efficiency. The mechanical and self-healing properties are significantly improved by using a small amount of mGO.

Preparation and Properties of Rubberlike High Polymers. II. Polymerization of Mixtures in Bulk

1947 ◽  
Vol 20 (2) ◽  
pp. 380-391
Author(s):  
C. Koningsberger ◽  
G. Salomon
Keyword(s):  
Mechanical Properties ◽  
Alder Reaction ◽  
Diels Alder ◽  
The Other ◽  
New Class ◽  
Diels Alder Reaction ◽  
Vinyl Compound ◽  
Other Hand ◽  
Higher Temperature ◽  
High Polymers

Abstract Mixtures of butadiene and dimethylbutadiene with varying quantities of styrene and acrylonitrile were copolymerized under various catalytic conditions at 100° C. The formation of cyclic dimers from dienes and vinyl compounds is, in some cases, much more pronounced than the dimerization of the dienes alone. Since the latter is also a kind of Diels-Alder reaction, a series with increasing dienophilic properties can be established from a comparison of the yields of cyclic dimers. From solubility and swelling experiments it is evident that the polymers prepared from butadiene and the vinyl compounds and those from dimethylbutadiene and acrylonitrile are true copolymers. The mechanical properties of the copolymers from butadiene and increasing amounts of a vinyl compound change gradually from those of a rubber to those of the polyvinyl compound. The copolymers from a mixture containing 30 per cent styrene or acrylonitrile are very similar to Buna-S and Perbunan, respectively. Copolymers of the same composition from dimethylbutadiene and acrylonitrile, on the other hand, form a new class of thermoplastics with a much higher temperature of elasticity.

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