Effect of resin staging on frontal polymerization of dicyclopentadiene

Abstract

In thermal frontal polymerization (FP), ambient temperature and staging conditions highly affect the resin behavior and front properties. This study describes the effect of staging conditions and resin reactivity on frontal ring opening metathesis polymerization of dicyclopentadiene in presence of phosphite-inhibited second-generation Grubbs catalyst. An experimental setup is designed to characterize and understand the effect of inhibitor concentration, incubation time, and incubation temperature on front velocity, activation time, and front temperature of the FP reaction. The results reveal that front properties are influenced by various factors, including available energy density of resin, stability of catalyst-inhibitor complex, resin temperature, and resin viscosity. An increase in staging temperature results in lower pot lives but faster gelation process and activation of FP reaction. Additionally, increasing the inhibitor concentration leads to slower fronts, higher activation times, and longer pot lives. The results of this study can be extended to other FP systems and can be used in design of new manufacturing processes and applications using FP.

3D Printing of Short-Carbon-Fiber-Reinforced Thermoset Polymer Composites via Frontal Polymerization

“…We use a frontally curable DCPD-based resin (Figure a) for developing composite inks. , Given that DCPD is solid at room temperature, first DCPD is melted in an oven at 60 °C and mixed with 5 wt % ENB to suppress the melting point of DCPD. The solution is stirred for 1 h to obtain a homogeneous mixture and degassed at 20 kPa overnight.…”

Frontal Polymerizations: From Chemical Perspectives to Macroscopic Properties and Applications

“…Fabrication of free-standing objects via 3D printing or extrusion necessitates appropriately modified resin rheologies. 155,160,161,164,364 Specifically, printing inks must exhibit shape retention after pressurized extrusion (i.e., low mechanical flow). The following materials properties address the aforementioned printing criterion; resins must exhibit shear yielding, shear thinning, and fast thixotropic recovery behavior.…”

“…Future efforts to achieve large-scale FP extrusion, however, may benefit from earlier works described in this review. 32,155,160,238,364 6. Summary and Outlook 6.1 Summary: Where are We Now?…”

Rapid and Energy-Efficient Frontal Curing of Multifunctional Composites Using Integrated Nanostructured Heaters

“…Among various frontally polymerizable resin systems, dicyclopentadiene (DCPD) is of great interest for fabricating FRPCs due to its excellent front properties and low resin viscosity combined with the good thermomechanical properties of the resulting polydicyclopentadiene (pDCPD) polymer. − Frontal ring opening metathesis polymerization (FROMP) of DCPD with tunable pot life has been recently shown using Grubbs' catalyst and phosphite inhibitors. ,− FP of DCPD has been recently used to produce FRPC panels with up to 50 vol % of carbon fibers by in-plane initiation and propagation (i.e., within the plane of reinforcements) of the reaction front. ,, However, the scalability and practical applications of the in-plane FP of DCPD is hindered by several processing issues and limitations. Self-sustaining propagation of the FP reaction in the presence of a high volume fraction of reinforcements has been demonstrated using a highly thermally insulating tooling material (i.e., polymer foams) to minimize the heat loss to the substrate during polymerization and mitigate the risk of frontal quenching. ,, Such tooling materials however are not common in the composite industry and are challenging to form and machine.…”