Rheology of end-linking polydimethylsiloxane networks filled with silica

2020 ◽  
Vol 64 (6) ◽  
pp. 1425-1438
Author(s):  
Huilong Xu ◽  
Lin Ding ◽  
Yihu Song ◽  
Wanjie Wang
Keyword(s):  
End Linking

Hydrogels prepared from polysiloxane chains by end linking them with trifunctional silanes containing hydrophilic groups

Polymer ◽  
2009 ◽  
Vol 50 (23) ◽  
pp. 5414-5421 ◽  
Author(s):  
Xiujuan Zhang ◽  
Gui Lin ◽  
Sai R. Kumar ◽  
James E. Mark
Keyword(s):  
End Linking

Dynamic viscoelasticity of end-linking α,ω-dimethyl silyl poly(propylene oxide) solutions near the gel point

Polymer ◽  
1994 ◽  
Vol 35 (14) ◽  
pp. 3005-3010 ◽  
Author(s):  
Akihiro Koike ◽  
Norio Nemoto ◽  
Masaoki Takahashi ◽  
Kunihiro Osaki
Keyword(s):  
Propylene Oxide ◽  
Gel Point ◽  
Dynamic Viscoelasticity ◽  
End Linking ◽  
Poly Propylene

Reinforcement from In-Situ Precipitated Silica in Polysiloxane Elastomers under Various Types of Deformation

1992 ◽  
Vol 274 ◽  
Author(s):  
James E. Mark ◽  
Shuhong Wang ◽  
Ping Xu ◽  
Jianye Wen
Keyword(s):  
Mechanical Properties ◽  
Uniaxial Elongation ◽  
Compression Set ◽  
Precipitated Silica ◽  
Equilibrium Swelling ◽  
Rupture Energy ◽  
End Linking ◽  
Reinforcing Effects

ABSTRACTElastomeric networks prepared by tetrafunctionally end linking hydroxyl-terminated poly(dimethylsiloxane) chains (PDMS) were filled by the in-situ precipitation of silica. The resulting networks were investigated under uniaxial elongation, biaxial extension, shear, and torsion in order to characterize the resulting changes in mechanical properties. Compared with the unfilled networks, the silica-filled materials showed large reinforcing effects. Specifically, their values of the modulus, ultimate strength, and rupture energy increased significantly. The results thus indicate that the PDMS networks filled by the in-situ precipitation of silica have very good mechanical properties in several, rather different deformations. Examples of other deformations of interest are equilibrium swelling, and dynamic cycling for characterization of compression set.

Model Polyelectrolyte Gels Synthesized by End-Linking of Tetra-Arm Polymers with Click Chemistry: Synthesis and Mechanical Properties

2014 ◽  
Vol 47 (21) ◽  
pp. 7573-7580 ◽  
Author(s):  
Kazuyuki Oshima ◽  
Taku Fujimoto ◽  
Erina Minami ◽  
Yoshiro Mitsukami
Keyword(s):  
Mechanical Properties ◽  
Click Chemistry ◽  
Polyelectrolyte Gels ◽  
End Linking

Simulation of the Formation of Elastomers

1988 ◽  
Vol 61 (2) ◽  
pp. 205-222 ◽  
Author(s):  
V. Galiatsatos ◽  
B. E. Eichinger
Keyword(s):  
Molecular Weight ◽  
Molecular Weight Distribution ◽  
Computer Simulations ◽  
Weight Distribution ◽  
Realistic Model ◽  
High Energy ◽  
Polymeric System ◽  
Intramolecular Reactions ◽  
End Linking ◽  
Cycle Rank

Abstract The formation of networks of various types has been simulated by using a physically realistic model that allows for intramolecular reactions to take place, thus forming loops of any size. The shortcomings of the kinetic approach, where systems are composed of functional groups that are selected at random without spatial constraint, and of the percolation method where an ordered arrangement is assured, are avoided. The reported simulations of the end-linking process illustrate the influence of intramolecular reactions on gel-sol distributions. Rings form in both phases, gel and sol. Neglect of the presence of cyclics in the sol underestimates the extent of the crosslinking reaction by several percent. On the other hand, in the gel fraction, loop defects are formed as the result of short-ranged intramolecular reactions. These defects do not vanish at complete conversion, and as a result they reduce the cycle rank in proportion to the number of primary chains reacting to form loops. The higher the molecular weight of the prepolymer chains, the closer to the perfect network the formed structure will be. Diffusion effects play an increasingly important role as the degree of polymerization goes up, so that reactions involving the end-linking of very long chains may never come into completion. The simulation results show that sol structures are highly dependent upon the functionality of the crosslinking agent used in the end-linking process. The intramolecular reactions which occur in substantial proportion at higher degrees of crosslinking necessarily favor formation of cyclics. In the case of tetrafunctional networks, this results in a bimodal molecular weight distribution of the sol constituents. It is important to realize that, according to the results of our simulation, networks obtained near complete conversions are very close to perfect. In the case of the random networks cured by high-energy radiation, we show that their properties are quite different when compared to those resulting from other crosslinking techniques. The defect structures account for a large portion of the mass of the networks and their mechanical moduli, as represented by the cycle rank per chain, are substantially smaller than the model networks. Results on both poly(dimethylsiloxane) and polyethylene show that chain scission is rather important. It should be kept in mind that primary chain branching and the molecular weight distribution affect the behavior of a polymeric system when it is exposed to radiation. The fact that the algorithm gives reliable results for more than one polymeric system shows the flexibility of the simulation program; it also proves that the assumptions used to build the model form a realistic basis for future work. A number of upgrades are being incorporated in the model at the present time. Instead of relying on the Gaussian distribution of chain ends, a more realistic model incorporating Flory's rotational isomeric state theory is being used to generate the prepolymer chains. The simulations are being applied to a number of different systems, including polyoxypropylene- and polyoxyethylene-based urethane networks. In addition, filled networks and sulfur vulcanization systems are slated to be explored in order to try to understand their rather complicated behavior. Computer simulations prove to be a powerful tool to study network structure problems. Questions about the detailed structure of the elastomer, sol-gel transitions, and the mechanical properties can be given reliable answers. Wherever there is sufficient knowledge of the reaction system and enough experimental data for comparison, computer simulations can provide information of unprecedented depth and accuracy.

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