Thermal processing of EVA encapsulants and effects of formulation additives

Book · Sun Sep 01 04:00:00 EDT 1996

OSTI ID:276866

Pern, F J; Glick, S H ^[1]

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1. National Renewable Energy Lab., Golden, CO (United States). Center for Performance Engineering, Qualification, and Reliability

The authors investigated the in-situ processing temperatures and effects of various formulation additives on the formation of ultraviolet (UV) excitable chromophores in the thermal lamination and curing of ethylene-vinyl acetate (EVA) encapsulants. A programmable, microprocessor-controlled, double-bag vacuum laminator was used to study two commercial as-formulated EVA films. A9918P and 15295P, and solution-cast films of Elvax{trademark} (EVX) impregnated with various curing agents and antioxidants. The results show that the actual measured temperatures of EVA lagged significantly behind the programmed profiles for the heating elements and were affected by the total thermal mass loaded inside the laminator chamber. The antioxidant Naugard P{trademark}, used in the two commercial EVA formulations, greatly enhances the formation of UV-excitable, short chromophores upon curing, whereas other tested antioxidants show little effect. A new curing agent chosen specifically for the EVA formulation modification produces little or no effect on chromophore formation, no bubbling problems in the glass/EVX/glass laminates, and a gel content of {approximately}80% when cured at programmed 155 C for 4 min. Also demonstrated is the greater discoloring effect with higher concentrations of curing-generated chromophores.

• DOE Contract Number: AC36-83CH10093
• OSTI ID: 276866
• Report Number(s): CONF-960513--
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
36 MATERIALS SCIENCE
ACETATES
COLOR
CURING
ENCAPSULATION
EXPERIMENTAL DATA
POTTING MATERIALS
SILICON SOLAR CELLS
TEMPERATURE DEPENDENCE