REPROCESSABLE POLYMER COMPOSITION WITH DYNAMIC CROSSLINKS

1 . A polymer composition having covalent bonding networks alterable by thermally-activated bond exchanges creating dynamic crosslinks comprising:

a silicon-oxygen backbone chain elastomer for creating a polymer network;

a non-agglomerating filler dispersed within and bonded to the polymer network;

a catalyst for facilitating a condensation reaction;

a crosslinker selected from one or more silanes that include one or more methoxy or ethoxy groups;

at least one dynamic bond activator promoting Si—O bond exchange between adjacent silicon-oxygen backbone chain elastomers of the polymer network such that dynamic crosslinks formed between the adjacent silicon-oxygen backbone chain elastomers create a three-dimensional crosslinked polymer network;

wherein, in bulk form, the polymer composition has properties of a thermosetting polymer at ambient condition and is capable of reshaping as a viscoelastic liquid at a temperature of greater than approximately 170° C.

2 . The polymer composition of claim 1 , wherein the silicon-oxygen backbone chain elastomer is selected from one or more of a trimethylsilyl-terminated polydimethyl siloxane and a silanol-terminated polydimethyl siloxane.

3 . The polymer composition of claim 2 , wherein the silicon-oxygen backbone chain elastomer has a molecular weight of 5,970 to 139,000 g/mol and a viscosity of 100 to 150,000 cSt and is present in the composition in an amount from 49.6 to 65.6 wt %.

4 . The polymer composition of claim 2 , wherein the filler comprises hexamethyldisilazane treated silica in an amount of 24.9 to 36.9 wt %.

5 . The polymer composition of claim 1 , wherein the at least one dynamic bond activator is an ionic salt selected from an ammonium salt or a phosphonium salt in an amount of 0.09 to 2.5 wt %.

6 . The polymer composition of claim 5 , where the at least one dynamic bond activator is tetrabutylphosphonium hydroxide.

7 . The polymer composition of claim 1 , wherein the at least one catalyst comprises dibutyltin dilaurate or dibutyltin dioctoate in an amount of 0.12 to 2.3 wt %.

8 . The polymer composition of claim 1 , wherein the crosslinker comprises silanes with ethoxy groups and silanes with methoxy groups, in an amount of 2.7 to 25.0 wt %.

9 . The polymer composition of claim 8 , wherein the crosslinker is selected from one or more of 1,2-bis(triethoxysilyl) ethane, poly(dimethoxysiloxane), poly(diethoxysiloxane), and tetraethyl silicate.

10 . The polymer composition of claim 1 , wherein the reshaped polymer composition retains a tensile strength of at least 60% of ambient tensile strength and at least 70% of ambient elongation at break.

11 . A method for preparing the polymer composition of claim 1 , comprising:

combining a first silicon-oxygen backbone chain elastomer with filler and the crosslinker to form a first mixture;

combining a second silicon-oxygen backbone chain elastomer with filler and the catalyst to form a second mixture;

combining the first mixture and the second mixture to form a third mixture, wherein the first mixture and the second mixture are combine in a weight ratio of 1.1:1 to 8.3:1;

combining the third mixture with at least one dynamic bond activator to form a fourth mixture; and

curing the fourth mixture to form the polymer composition.

12 . The method of claim 11 , further comprising heating the polymer composition in vacuum at a temperature of 50 to 80° C.