Effects of Organic Peroxides on the Curing Behavior of EVA Encapsulant Resin

Abstract

Compounds of poly(ethylene-co-vinyl acetate) (EVA with vinyl acetate content 33%) with three different organic peroxides, namely, dialkyl peroxide, peroxyester peroxide, and peroxyketal peroxide, were prepared with a twin screws extruder and a two-roll mixing mill. The cure behavior of the EVA compounds was analyzed from rheographs, which were obtained by a moving die rheometer (MDR) at various curing temperatures between 150˚C to 170˚C. The effects of organic peroxides on cure behavior were examined. The dynamic curing obtained by the torque rheometer provided sufficient experimental data to show that dialkyl peroxide is not suitable because it has a high half-life temperature and its by-products can discolor the final product. Peroxyester peroxide is good for curing at temperatures in the range of 150˚C to 160˚C, which accomplished an ultimate cure within 5 to 8 minutes. Also, the peroxyketal peroxide has higher performance, which decreased the optimum cure time to 3 minutes. The thermal decomposition mechanism of organic peroxide was applied to explain how the cure behavior is affected by generated free radicals.

A comparative study of calorimetric methods to determine the crosslinking degree of the ethylene-Co-vinyl acetate polymer used as a photovoltaic encapsulant

“…) was applied to a standard first‐order kinetic decomposition of different peroxides which have been reported in the literature as possible candidates for the crosslinking of EVA. The first‐order kinetics decomposition constant for a given peroxide at different temperatures can be obtained by deducing the activation energy from decomposition half‐life data available in the literature . For each iteration of a Δ t time (and thus for a mean temperature of Δ T ), the isothermal decomposition kinetic constant of the peroxide k d can be determined.…”

Non-isothermal crosslinking of ethylene vinyl acetate initiated by crosslinking agents: kinetic modelling

“…Therefore, understanding the effect of the crosslinking agent on the crosslinking process of EVA samples is of crucial importance in selecting a suitable crosslinking agent and optimizing the lamination process. 24 …”

“…Therefore, understanding the effect of the crosslinking agent on the crosslinking process of EVA samples is of crucial importance in selecting a suitable crosslinking agent and optimizing the lamination process. 24 The crosslinking process of EVA in the solid or melting state follows a complex mechanism involving several reaction steps, and the apparent activation energy and rate of EVA crosslinking reaction increase with increasing of the vinyl acetate (VA) content. 25 Several mathematical models of non-isothermal kinetics, such as Avrami, Ozawa, and Mo methods, have been developed to describe the crystallization kinetics.…”

Relationships of tensile strength with crosslink density for the high‐carbon black‐filledEPDMcompounds with various softeners

“…The reaction of peroxides curing system takes the thermal decomposition of peroxides as the initial step, and the generated free radicals capture hydrogen atoms from the EPDM molecular chain to generate rubber macromolecules free radicals. [ 6–11 ]…”