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.

Diels-Alder Reaction Curing of Chlorobutyl Rubber by bis-Maleimides

1989 ◽  
Vol 62 (1) ◽  
pp. 42-54 ◽  
Author(s):  
K. Ho ◽  
R. Steevensz
Keyword(s):  
Zinc Oxide ◽  
Double Bond ◽  
Chain Length ◽  
Crosslinking Agent ◽  
Alder Reaction ◽  
Diels Alder ◽  
Diels Alder Reaction ◽  
Electronic Distribution ◽  
Curing Agents ◽  
Chlorobutyl Rubber

Abstract Different bis-maleimides are found to have different efficiencies and reactivities in the crosslinking of CIIR in the presence of zinc oxide. Although the degrees of crosslinking of CIIR by bis-maleimides cannot be defined absolutely, some trends concerning the efficiencies of the crosslinking are evident. In general, the aromatic bis-maleimides gave higher degrees of crosslinking than the aliphatic analogs. The reactivity and crosslinking efficiency of an individual bis-maleimide is very much affected by its end-to-end chain length and its electronic distribution, resulting from the interaction between the maleimide groups, and from the interaction between the maleimide groups and other functional groups present in the same molecule. The longer the bis-maleimide molecule and the more electron deficient the maleimido double bond, the greater its effectiveness as a crosslinking agent. Other curing mechanisms, possibly including polymerization of the maleimido groups, appear to be operative when using aromatic bis-maleimides as curing agents for CIIR.

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 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.

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 Recyclable Multilayer Packaging by Means of Thermoreversibly Crosslinking Adhesive in the Context of Food Law

Polymers ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 2988
Author(s):  
Katharina M. A. Kaiser ◽  
Johann Ewender ◽  
Frank Welle
Keyword(s):  
Crosslinking Agent ◽  
Alder Reaction ◽  
Diels Alder ◽  
Point Of View ◽  
Ethylene Vinyl Alcohol ◽  
Residual Content ◽  
Diels Alder Reaction ◽  
Food Law ◽  
Lag Times ◽  
Activation Energy Of Diffusion

Lacking recyclability of multilayer packaging can be overcome by using a thermoreversible crosslinking adhesive consisting of maleimide- and furan-functionalized polyurethane-(PU-)prepolymers, reacting in a Diels–Alder-reaction. Here, the furan-functionalized PU-prepolymer carries furan-side-chains to avoid the usage of an additional crosslinking agent. Thus, N‑(2‑hydroxyethyl)maleimide and furfurylamine are the only two chemicals contained in the adhesive that are not listed in the appendix of EU Regulation 10/2011. Using migration modelling, it could be shown that, at 23 °C, both chemicals have lag-times of only a few minutes if 45 µm PE is used as a barrier. However, if the residual content is below 30 mg/kg, the legally specified maximum amount of 0.01 mg/kg food is not reached. After determining the diffusion coefficients and the activation energy of diffusion through ethylene-vinyl alcohol copolymer (EVOH), it could be determined that the lag-time of the migrants can be extended to at least 9 years by the use of 3 µm EVOH. From a food law point of view, the use of the described adhesive is possible if the above‑mentioned measures are complied.

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.

scholarly journals Identifying the Co-Curing Effect of an Accelerated-Sulfur/Bismaleimide Combination on Natural Rubber/Halogenated Rubber Blends Using a Rubber Process Analyzer

Polymers ◽  
2021 ◽  
Vol 13 (24) ◽  
pp. 4329
Author(s):  
Marek Pöschl ◽  
Shibulal Gopi Sathi ◽  
Radek Stoček
Keyword(s):  
Natural Rubber ◽  
Early Stage ◽  
Alder Reaction ◽  
Constant Frequency ◽  
Rubber Blends ◽  
Curing Reaction ◽  
Test Methodology ◽  
Diels Alder Reaction ◽  
Complex Test ◽  
Network Strength

The rheometer curing curves of 50/50 blends of natural rubber (NR) and two different halogenated rubbers with a combination of conventional accelerated sulfur (CV) and 3 phr of a bismaleimide (MF3) at 170 °C indicates that a co-curing reaction has been taken place between NR and the halogenated rubbers via Diels–Alder reaction. To further confirm whether the co-curing reaction has taken place in the early stage of curing, a complex test methodology was applied with the help of a rubber process analyzer. In this test, the blends with CV and with CVMF3 were subjected to cure at 170 °C for a predetermined time so that both the CV and CVMF3 cured blends will have the same magnitude of curing torque. It is then cooled down to 40 °C and the storage modulus (G′) was evaluated as a function of strain from 0.5% to 100% at a constant frequency of 1 Hz. The results reveal that the blends cured with CVMF3 exhibit a higher G′ due to the enhanced network strength because of the formation of bismaleimide crosslinks than the same cured with only the CV system. The swelling resistance and the mechanical properties of the blends cured with CVMF3 were significantly higher than those cured with only the CV system.

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