Programmable adhesive based upon Diels-Alder chemistry

Abstract

Disclosed is an adhesive formulation that, when stimulated by a defeatable stimulation, reduces an adhesive bonding force of the adhesive formulation and defeats the adhesive formulation. The adhesive formulation having (i) programmable linkages made from Diels-Alder adducts and (ii) a concentration of diene traps. The Diels-Alder adducts may be furan-maleimide, and the diene traps may be (i) latent alkenes and (ii) selected from functional groups that will create irreversible reations with furan. The adhesive formulation may be capable of being applied as a coating, and the adhesive formulation may be capable of being extruded. The adhesive formulation may have a bonding temperature between 75 and 120° C. And the defeatable stimulation could, for example, be a temperature above 130° C. The adhesive formulation also may contain several types of programmable linkages and diene traps.

Claims

1. An adhesive formulation, wherein when the adhesive formulation is stimulated by a defeatable stimulation an adhesive bonding force is reduced and the adhesive formulation is defeated, the adhesive formulation comprising (i) programmable linkages made from Diels-Alder adducts and (ii) a concentration of diene traps, wherein: the Diels-Alder adducts comprise diene (furan)-dienophile (maleimide), the diene traps are (i) latent alkenes and (ii) selected from functional groups that will create irreversible reations with furan, wherein moles of the diene trap exceed moles of the furan; the adhesive formulation is capable of being applied as a coating, the adhesive formulation is capable of being extruded, the adhesive formulation has a bonding temperature between 75 degrees Celsius and 120 degrees Celsius, and the defeatable stimulation is a temperature above 130 degrees Celcius.

2. An adhesive film generated by the adhesive formulation according to claim 1 through coating methods.

3. An adhesive film generated by the adhesive formulation according to claim 1 through extrusion methods.

4. A textile laminate made using the adhesive formulation according to claim 1.

5. A plastic laminate made using the adhesive formulation according to claim 1.

6. A composite structure made using the ahesive formulation according to claim 1.

7. The adhesive formulation according to claim 1, wherein the adhesive formulation includes one or more additives to improve flow, bonding, or other behavior.

8. The adhesive formulation according to claim 1, wherein a mole ratio of the dienophile (maleimide) to the diene (furan) is 0.10-0.75.

9. The adhesive formulation according to claim 1, wheren a mole ratio of the dienophile (maleimide) to the diene (furan) is 0.10-0.50.

10. The adhesive formulation according to claim 1, wherein mole ratio of the dienophile (maleimide) to the diene (furan) is 0.15-0.30.

11. The adhesive formulation according to claim 1, wherein a mole ratio of the diene trap to the diene ranges from greater than 1 to −25.

12. The adhesive formulation according to claim 1, wherein a mole ratio of the diene trap to the diene ranges from 5 to −15.

13. The adhesive formulation according to claim 1 further comprising non-programmable linkages that do not disassociate upon application of the defeatable stimulation.

14. The adhesive formulation according to claim 13, wherein the non-programmable linkages include isocyanate functional groups, and a mole ratio between the programmable linkages and the non-programmable linkages is 0.01-4.0.

15. The adhesive formulation according to claim 13, wherein a mole ratio between the programmable linkages and the non-programmable linkages is 0.1-1.0.

16. The adhesive formulation according to claim 13, wherein a mole ratio between the programmable linkages and the non-programmable linkages is 0.5-0.9.

17. A method of forming an adhesive, the method comprising: forming a polymer including a diene, a dienophile, and a diene trap, wherein: the diene and dienophile react to form a first Diels-Alder adduct; the diene and the diene trap react to form a second Diels-Alder adduct; moles of the diene trap exceed moles of the diene; a retro Diels-Alder reaction of the first Diels-Alder adduct is dominant at a defeatable temperature of the adhesive; a retro Diels-Alder reaction of the second Diels-Alder adduct is not dominant at the defeatable temperature of the adhesive; the first Diels-Alder adduct comprises furan-maleimide; the diene trap is (i) a latent alkene and (ii) selected from functional groups that will create irreversible reactions with furan; the adhesive has a bonding temperature between 75 degrees Celcius and 120 degrees Celcius; and the defeatable temperature is a temperature above 130 degrees Celcius.

18. The method of according to claim 17, wherein the polymer further includes non-programmable linkages that do not disassociate at the defeatable temperature.

19. The method according to claim 17, wherein the concentration of diene traps comprises polybutadiene.

20. The method according to claim 1, wherein the concentration of diene traps comprises polybutadiene.

21. The method according to claim 1, wherein the adhesive formulation contains several types of the programmable linkages and the diene traps.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 depicts the stages of forming a polymer.

(2) FIG. 2 depicts operating temperature windows for various Diels-Alder systems.

(3) FIG. 3 depicts the stages of forming and defeating a defeatable polymer by increasing temperature.

DETAILED DESCRIPTION

(4) FIG. 1 shows the formation of a polymer using Diels-Alder adducts. As shown in that figure, in A-Stage, the prepolymer stage, cross-linking is minimal. With the addition of heat, the reaction proceeds into B-Stage, where a significant number, but not all, of the possible cross-linkages have formed. For adhesives, B-Stage may be particularly suitable for commercial use, since the adhesive can be applied to a surface and then cured to its final stage where the adhesive is activated. Further increasing the temperature shifts the reaction to C-Stage, in which full linkage occurs and the polymer is fully cured, i.e., the adhesive is now activated.

(5) FIG. 2 shows the operating temperature windows for exemplary Diels-Alder systems. The top portion of that figure shows a Diels-Alder system involving modified anthracene (diene) and modified ethylene (dienophile) and modified maleimide (also a dienophile). The bottom portion of FIG. 2 depicts modified furan (diene) in a Diels-Alder system with these same two dienophiles. The arrows depict the temperature regions in which the normal adduct-forming Diels-Alder reaction dominates (solid arrows) and in which the retro Diels-Alder reaction dominates (dashed arrows).

(6) As discussed above, a desirable defeatable adhesive may be one such that the adduct composed of the available free diene and the “diene trap”—a particularly selected dienophile, as discussed above—does not undergo retro Diels-Alder reaction at the defeatable temperature. That is, at the defeatable temperature, diene-dienophile adducts, i.e., adducts not including the diene trap, will undergo retro Diels-Alder reaction and separate; however, diene-diene trap adducts will not undergo retro Diels-Alder at this same temperature.

(7) In the bottom of FIG. 2, the adduct formed by the modified furan (diene) and the modified ethylene (acting as a diene trap) does not undergo significant retro Diel-Alder reaction until the temperature approaches 150° C. Conversely, the retro Diels-Alder reaction is the dominant reaction for the modified furan (diene) and modified maleimide (dienophile) adduct even before the temperature exceeds 100° C.

(8) Thus, as FIG. 2 shows, there exists a region in which the diene-dienophile adducts are separating via retro Diels-Alder and the diene-diene trap adducts are not separating, and in fact, more diene-diene trap adducts may be forming between lone dienes separated from dienophiles by retro Diels-Alder and the remaining diene traps. Since the diene-dienophile adducts are the linkages holding the polymer together, heating the adhesive to this region and severing the diene-dienophile adducts thus defeats the adhesive. And so long as enough diene-diene trap adducts are formed, the polymer will not reform as the temperature drops, since any free dienes will likely have undergone a Diels-Alder reaction with the diene traps as soon as they were released from their diene-dienophile adducts.

(9) In short, when the defeatable stimulation is applied, e.g., the polymer is heated to the defeatable temperature, the retro Diels-Alder reaction is the dominant reaction for the original diene-dienophile adduct and the adduct separates into diene and dienophile. But the diene trap is chosen such that the defeatable temperature is low enough that the adduct formed by the diene-diene trap does not undergo significant retro Diels-Alder reaction. Thus, any free dienes resulting from the retro Diels-Alder reaction in the original diene-dienophile are captured by the diene trap and do not reform, even if the defeatable stimulus is later removed, e.g., temperature is subsequently lowered. Since the diene-dienophile bonds are necessary to maintain the functioning of the adhesive, the capture of the dienes by the diene trap defeats the adhesive.

(10) This process of defeating the adhesive is shown in FIG. 3. That figure shows an A-Stage, B-Stage, and C-Stage similar to those of FIG. 1. However, in FIG. 3, the specific examples of modified furan (diene), modified anthracene (diene) and modified maleimide (dienophile) are used. In addition to these three stages, FIG. 3 also depicts “D-Stage,” in which the network is defeated by increasing the temperature until the diene-dienophile adducts separate. As mentioned above, the diene trap will then react with the free dienes to create diene-diene trap adducts, preventing the reformation of polymer linkages and thus defeating the adhesive.

(11) As discussed above, achieving this behavior involves creating a balance between the reversible and irreversible linkages in order to ensure that the resulting adhesive can both (i) last for the lifetime of the intended product and (ii) be weakened or defeated when exposed to the defeatable stimulus. By creating formulations that specifically target the defeatable stimulus, e.g., temperature, it is possible to create an adhesive with strong adhesive capabilities that displays the desired dehiscence behavior.

(12) A potentially important aspect in creating this defeatable behavior is the concentrations of the diene, dienophile, and diene trap. As discussed above, the dienophile is denoted by A, the diene by B, and the diene trap by AT. In some preferred embodiments, the concentration of diene will exceed that of the dienophile, as discussed above, preferably with a mole ratio of dienophile to diene, A:B, of 0.10-0.75, more preferably 0.10-0.50, and even more preferably 0.15-0.30. Likewise, in some preferred embodiments, the concentration of the diene trap exceeds the concentration of the diene, preferably with a mole ratio of diene trap to diene, AT:B, of 1-25, and more preferably 5-15.

(13) As also discussed above, it may be important to maintain the ratio of programmable linkages to the amount of non-programmable linkages, i.e., linkages involving additional isocyanate functional groups that provide network connectivity but will not themselves thermally dissociate when the defeatable stimulus is applied. For a fully debondable system, a mole ratio between the programmable linkages and non-programmable linkages should be preferably 0.01-4.0, more preferably 0.1-1.0, and even more preferably 0.5-0.9.

(14) Modified furan, modified anthracene, modified ethylene, and modified maleimide are used only as examples in this disclosure. As discussed above, the diene, dienophile, and diene trap may be any of those listed earlier, alone or in combination, so long as their combination results in a defeatable adhesive. Further, the use of increased temperature as a defeatable stimulus is also exemplary. The defeatable stimulus may be any stimulus that selectively allows for breaking down the bonds of the adhesive thus accomplishing the intended effect of the defeatable adhesive. Other defeatable stimuli might include, for example, lower temperature, changes in pH or pOH, application of defeatable agent, e.g., a chemical agent, application of pressure, or any other stimulus that selectively results in a defeatable adhesive.

(15) Also, in a full formulation, any additional additives that do not interfere specifically with the specified diene, dienophile, and diene trap may be added to the formulation. For instance, such additives may include small molecule, oligomer, or polymeric species that are specifically added to tune properties like adhesion, flow, mechanical strength, bonding temperature, debonding temperature, application properties, process properties, or any other desired property that does not interfere with the adhesive defeatability mechanic.

(16) Discussed below are the creation and testing of various manifestation of the adhesive described above. These experimental results are intended to be illustrative and not to limit the scope of the disclosure in any way.

(17) Synthesis of PB-Derived Adhesive Formulations

(18) The following section outlines typical procedures for preparation of the thermally-defeatable adhesive product (PL/PB). Experiments were conducted according to the general synthetic procedures outlined below, with specific chemical compositions and reagent amounts reported in Table 1. Various reaction conditions were employed according to key synthetic variables and chemical ratios explored, as shown in Table 2.

(19) All formulations were subsequently drawn down with a #50 mayer rod on a one side silicone coated release liner and prepared for adhesive testing.

(20) TABLE-US-00001 TABLE 1 Composition of materials prepared: Reagent amounts added General 1st 2nd Formulation Addition Addition Procedure Sample 1,6 HMDI Of 2-FA HTPB Of 2-FA PM A HRD 7-A13 4.27 mL 1.53 mL 29.8 g 0.77 mL   5 g (26.4 mmol) (17.6 mmol) (10.6 mmol) (8.82 mmol) (26.7 mmol) HRD 9-A15 3.22 mL 0.78 mL   15 g 0.39 mL  2.5 g (20.1 mmol) (8.93 mmol) (5.36 mmol) (4.47 mmol) (13.4 mmol) HRD 10-A16 3.22 mL 1.16 mL   5 g 0.39 mL 3.34 g (20.1 mmol) (13.4 mmol) (1.78 mmol) (4.47 mmol) (17.87 mmol) JAP 26-A52 3.21 mL 0.78 mL   15 g  .39 mL 2.51 g (20.1 mmol) (8.93 mmol) (5.36 mmol) (4.46 mmol) (13.4 mmol) JAP 27-A54 2.14 mL 0.78 mL   15 g  .39 mL 2.51 g (13.4 mmol) (8.93 mmol) (5.36 mmol) (4.47 mmol) (13.4 mmol) A2 HRD 12-A18 2.98 mL  1.3 mL   25 g 0.65 mL 2.09 g (18.6 mmol) (14.9 mmol) (8.9 mmol) (7.44 mmol) (11.2 mmol) JAP 29-A58  3.6 mL 1.29 mL   25 g  .65 ml 4.17 g (22.3 mmol) (14.9 mmol) (8.93 mmol) (7.4 mmol) (22.3 mmol) HRD 13-A19 4.29 mL  1.3 mL   25 g 0.65 mL 4.17 g (26.78 mmol) (14.9 mmol) (8.93 mmol) (7.44 mmol) (22.3 mmol) JAP 29-A59  3.6 mL 1.29 mL   25 g  .65 mL 4.17 g (22.3 mmol) (14.9 mmol) (8.93 mmol) (7.4 mmol) (22.3 mmol) HRD 19-A26 4.29 mL  1.3 mL   25 g 0.65 mL 4.17 g (26.78 mmol) (14.9 mmol) (8.93 mmol) (7.44 mmol) (22.3 mmol) JAP 36-A74 4.29 mL  1.3 mL   25 g  .65 mL 4.17 g (26.8 mmol) (14.9 mmol) (8.93 mmol) (7.4 mmol) (22.3 mmol) HRD-15-A21 3.57 mL  1.3 mL   25 g 0.65 mL 4.17 g (22.3 mmol) (14.9 mmol) (8.9 mmol) (7.44 mmol) (22.3 mmol) A3 JAP 30-A60  3.6 mL 1.29 mL   25 g  .65 mL 4.17 g (22.3 mmol) (14.9 mmol) (8.93 mmol) (7.4 mmol) (22.3 mmol) C HRD 14-A20  5.4 mL 1.94 mL   25 g 0 4.17 g (33.5 mmol) (22.3 mmol) (8.9 mmol) (22.3 mmol) D HRD 18-A25 2.62 mL 0.78 mL   25 g 0.39 mL  2.5 g (16.37 mmol) (8.93 mmol) (8.93 mmol) (4.47 mmol) (13.4 mmol) JAP 31-A62  3.6 mL 1.29 mL   25 g  .65 mL 4.17 g (22.3 mmol) (14.9 mmol) (8.93 mmol) (7.4 mmol) (22.3 mmol) JAP 32-A64 3.15 mL 0.78 mL   25 g 0.39 mL  2.5 g (19.64 mmol) (8.93 mmol) (8.93 mmol) (4.47 mmol) (13.39 mmol) JAP 33-A66 4.29 mL 1.29 mL   25 g  .64 mL 4.17 g (27.76 mmol) (14.9 mmol) (8.93 mmol) (7.4 mmol) (22.3 mmol) JAP 34-A68  3.6 mL 1.29 ml   25 g  .65 mL 4.17 g (22.3 mmol) (14.9 mmol) (8.93 mmol) (7.4 mmol) (22.3 mmol)

(21) TABLE-US-00002 TABLE 2 Composition of materials prepared: Key synthetic ratios explored. Eq. Amount NCO:OH of 2-FA (Initial Eq. Eq. added 1st mL. 2-FA NCO:OH HTPB:Diels- addtn.:2nd THF:g. Formulation Sample addition) (Overall) Alder addtn. HTPB A HRD 7-A13   3:1 1:1.5  1:2.5 2:1 N/A HRD 9-A15 4.5:1 1:1   1:1   2:1 1.27:1 HRD 10-A16   3:1 1:1   1:4   3:1 3.36:1 JAP 26-A52 4.5:1 1:1   1:2.5 2:1   1:1 JAP 27-A54   3:1 1:1.5  1:2.5 2:1 0.77:1 A2 HRD 12-A18 3.7:1 1:1.5  1:2.5 2:1 1.07:1 HRD 13-A19 3.6:1 1:1.25 1:2.5 2:1   1:1 JAP 29-A59   3:1 1:1.5  1:2.5 2:1   1:1 HRD 19-A26 3.6:1 1:1.25 1:2.5 2:1   1:1 JAP 36-A74 3.6:1 1:1.25 1:2.5 2:1 1.05:1 A3 JAP 30-A60   3:1 1:1.5  1:2.5 2:1   1:1 C HRD 14-A20   3:1 1:1   1:2.5 1:0   1:1 D HRD 18-A25 3.7:1 1:1.5  1:1.5 2:1  0.5:1 JAP 31-A62   3:1 1:1.5  1:2.5 2:1 0.58:1 JAP 32-A64 4.4:1 1:1.25 1:1.5 2:1 0.82:1 JAP 33-A66 3.6:1 1:1.25 1:2.5 2:1 0.78:1 JAP 34-A68   3:1 1:1.5  1:2.5 2:1  0.5:1
Representative Synthesis of Programmable Linkages

(22) A representative example of the synthesis of polybutadiene(PB)-based programmable linkages follows. A magnetic stir bar and 1,6 hexamethylene diisocyanate (4.27 mL, 0.026 mol, 78 mmol NCO) are placed into a round bottom flask (RBF). Next, 2-furfuryl alcohol (1.53 mL, 0.017 mol, 1 eq OH) and one drop of catalyst DBTDL are combined in a separate flask and added at RT dropwise to the RBF containing 1,6 hexamethylene diisocyanate over the course of 15 min. The product is then verified via TLC. After an hour at room temperature add HTPB to the reaction flask (28.6 g, 25.5 mmol OH).

(23) From here, the contents of the reaction flask are split, yielding RBF(A) and RBF(B), each with an equal, homogeneous mixture of the reaction contents. Into each new RBF, 2-furfuryl alcohol (0.383 mL, 4.25 mmol, 0.25 eq OH) is added. RBF(A) stirs at RT and RBF(B) at 60° C. for a duration of 2 hrs. Now, add phenolic maleimide (2.5 g, 0.0131 mol, 0.75eq) into both reaction flasks and let stir at 50° C. overnight.

(24) A representative example of the synthesis of soybean-oil-based programmable linkages can be found in Costanzo, et Al. Polym. Chem., 2014, 5, 69-76). The contents of this article are hereby incorporated herein by reference in their entirety.

(25) Adhesive Formulation ‘A’ General Procedure:

(26) A 100 mL round bottom flask (RBF) was loaded with 1,6 hexamethylene diisocyanate (HMDI) and a magnetic stir bar and chilled over ice and brine for 10 minutes. In a separate vessel, 2-furfuryl alcohol (2-FA) and a drop of dibutyltin dilaurate (DBTDL) were combined and added into the reaction vessel dropwise while stirring. The reaction vessel was then removed from the ice and brine and allowed to stir at room temperature for 1 hour, adding minimal tetrahydrofuran (THF) to keep reagents dissolved. The amount of THF added overall through the reaction was not to exceed 1 mL THF for each gram of Hydroxyl-terminated polybutadiene (HTPB) (Poly bd® R45 HTLO) added. HTPB was then added with additional THF. Once the contents were homogeneously mixed, a second addition of 2-furfuryl alcohol was made. The mixture then stirred for 2 hours. At 30 this time, N-(4-Hydroxyphenyl)maleimide (PM) was added and the reaction stirred until homogeneously mixed by visual inspection. Once done, the vessel was then capped with a rubber septum, secured with copper wire, and placed in an oil bath to stir at 50° C. overnight. The product was then characterized via HNMR.

(27) Adhesive Formulation ‘A2’ General Procedure:

(28) A 100 mL RBF was loaded with HMDI and a magnetic stir bar and chilled over ice and brine for 10 minutes. In a separate vessel, 2-FA, a drop of DBTDL, and THF (20% by volume of 2-FA) were combined and added into the reaction vessel dropwise. The reaction vessel was then removed from the ice and brine and allowed to stir at room temperature for 1 hour. A solution of HTPB and THF (in a ratio of 1 mL of THF for each gram of HTPB) was then added. Once the contents were homogeneously mixed, a second addition of 2-FA was made and stirred at room temperature for 2 hours. At this time, PM was added and stirred into the reaction until homogeneously mixed by visual inspection. The vessel was then capped with a rubber septum, secured with copper wire, and remained stirring in an oil bath at 50° C. overnight. The product was then characterized via HNMR.

(29) Adhesive Formulation ‘A3’ General Procedure:

(30) A 100 mL RBF was loaded with HMDI and a magnetic stir bar and chilled over ice and brine for 10 minutes. In a separate vessel, 2-FA and a drop of DBTDL were combined and added into the reaction vessel dropwise. The reaction vessel was then removed from the ice and brine and allowed to stir at room temperature for 1 hour. A solution of HTPB and THF (in a ratio of 1 mL of THF for each gram of HTPB) was then added. Once the contents were homogeneously mixed, a second addition of 2-FA was made and stirred at room temperature for 2 hours. At this time, PM was added and stirred into the reaction until homogeneously mixed by visual inspection. The vessel was then capped with a rubber septum, secured with copper wire, and remained stirring in an oil bath at 50° C. overnight. The product was then characterized via HNMR.

(31) Adhesive Formulation ‘C’ General Procedure:

(32) A 100 mL RBF was loaded with HMDI and a magnetic stir bar and chilled over ice and brine for 10 minutes. In a separate vessel, 2-FA and a drop of DBTDL were combined and added into the reaction vessel dropwise. The reaction vessel was then removed from the ice and brine and allowed to stir at room temperature for 1 hour. A solution of HTPB and THF (in a ratio of 1 mL of THF for each gram of HTPB) was then added, and the contents were homogeneously mixed. Next, PM was added and stirred into the reaction until homogeneously mixed by visual inspection. The vessel was then capped with a rubber septum, secured with copper wire, and remained stirring in an oil bath at 50° C. overnight. The product was then characterized via HNMR.

(33) Adhesive Formulation ‘D’ General Procedure:

(34) A 100 mL RBF was loaded with HMDI and a magnetic stir bar and chilled over ice and brine for 10 minutes. In a separate vessel, 2-FA and a drop of DBTDL were combined and added into the reaction vessel dropwise. The reaction vessel was then removed from the ice and THF was added, followed by a quick addition of HTPB (in a ratio of THF not to exceed 1 mL of THF for each gram of HTPB). Once the contents were homogeneously mixed, a second addition of 2-FA was quickly made, followed by an addition of PM that was stirred into the reaction until homogeneously mixed by visual inspection. The vessel was then capped with a rubber septum, secured with copper wire, and remained stirring in an oil bath at 50° C. overnight. The product was then characterized via HNMR.

(35) Adhesive Formulation with Soybean Oil (SBO)-Based Programmable Linkage Free Alcohol SBO

(36) Non-Acetylated TR-SBO (6 g, 2.53 mmol) was added to a round bottom flask with a magnetic stir bar. Hydroxyl-terminated polybutadiene (12 g, 4.28 mmol) was added in full to the flask then left to stir for 45 minutes. The flask was removed from the stir plate and manually mixed for a minute before 3 drops of dibutyltin dilaurate were added in as a catalyst and stirred for another minute. 1,6-hexamethylene diisocyanate (2.64 mL, 16.5 mmol) was then added and mixed for a minute. The resin was periodically checked for cure progress and after 45 minutes drawdowns were performed with an RDS #50 bar.

(37) Acetylated SBO

(38) Acetylated TR-SBO (6 g, 2.3 mmol) and Hydroxyl-terminated polybutadiene (12 g, 4.28 mmol) were added to a 11-dram vial. The components were manually stirred until a cohesive mix was achieved (3 minutes) 0.3 drops of dibutyltin dilaurate were mixed in as a catalyst for a minute. 1,6-hexamethylene diisocyanate (1.69 mL, 10.53 mmol) was then added and mixed for a minute. The resin was periodically checked for cure progress and after 45 minutes drawdowns were performed with an RDS #50 bar and labeled as RTH 40.

(39) Adhesive Testing of Defeatable Adhesive Formulations General Procedure for Testing Formulations

(40) Formulation drawdowns were cut into 4 inch by 4 inch coupons and applied to a 4 inch by 6 inch sized 100% polyester knit fabric. The adhesive coupon was then tacked to the fabric through application of heat and pressure (typically 65° C. for 30 s) using a Nurxiovo manual heat press. The release liner was then removed from the laminate, leaving the adhesive exposed and another layer of fabric was applied to the stack. This configuration was then bonded under various combinations of time, temperature, and pressure to create a fully bonded laminate.

(41) These laminate structures were cut into 1.0 inch strips and evaluated using a t-peel methodology on a universal tensile testing machine to evaluate the peel strength.

(42) TABLE-US-00003 TABLE 3 Peel strength of various adhesive formulations after bonding. N/A samples were either unable to bond or the strength was too low to measure. Average Peel Strength Sample (N/m) HRD 7-A13  87 HRD 9-A15  28 HRD 10-A16  87 JAP 26-A52 N/A JAP 27-A54 N/A HRD 12-A18 N/A JAP 29-A58  15 HRD 13-A19 200 JAP 29-A59  15 HRD 19-A26 N/A JAP 36-A74 N/A HRD-15-A21 N/A JAP 30-A60  15 HRD 14-A20  12 HRD 18-A25 N/A JAP 31-A62 N/A JAP 32-A64 160 JAP 33-A66  50 JAP 34-A68 N/A RTH 40  30
Debonding-Dehiscence Testing of Defeatable Adhesive Formulations

(43) Samples that were bonded with over 100 N/m peel strength were exposed to 150° C. for 60 seconds on the heat press to determine strength after high heat exposure. After cooling, they were tested and had a peel strength too low for our instrument to measure.