Effect of the addition of depolymerised ethylene vinyl acetate on the mechanical, thermal, chemical and shrinkage properties of cured unsaturated polyester resins

Unsaturated polyester resins (UPRs) are versatile compounds. However, their major drawback is the high shrinkage exhibited on curing. An attempt was made to reduce the shrinkage of UPRs without affecting other properties. In the present study a commonly used iso‐reactive UPR was modified by the addi...

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Bibliographic Details
Published in:Polymer international 2010-06, Vol.59 (6), p.867-874
Main Authors: Shenoy, Mohan A, D'Mello, Dawid, Patil, Mrinalini
Format: Article
Language:English
Subjects:
Applied sciences
branching
Chemical properties
Compounding ingredients
controlled depolymerisation
Curing
Dispersions
Ethylene vinyl acetates
Exact sciences and technology
low-profile additive
Miscellaneous
Molecular weight
Polyester resins
Polymer industry, paints, wood
Properties and testing
Shrinkage
Technology of polymers
Unsaturated
unsaturated polyester resin
Wastes
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Summary:Unsaturated polyester resins (UPRs) are versatile compounds. However, their major drawback is the high shrinkage exhibited on curing. An attempt was made to reduce the shrinkage of UPRs without affecting other properties. In the present study a commonly used iso‐reactive UPR was modified by the addition of ethylene–vinyl acetate (EVA; subjected to controlled depolymerisation to obtain samples of various molecular weights), and was cured at room temperature. The peak exotherm temperature and gel time were both observed to decrease with an increase in EVA content. The composition incorporating 0.5% of depolymerised EVA1 (highest degree of branching) showed maximum improvement in tensile and flexural properties with the heat deflection temperature and impact properties remaining almost unaffected. A uniform dispersion for the UPR containing 0.5% of EVA1 was observed. Addition of EVA reduced the percentage shrinkage in the modified matrix. Incorporation of depolymerised EVA can be an attractive option for the reduction of shrinkage in UPRs. The advantage of using depolymerised EVA is that generated waste EVA can be depolymerised and reused for this application making it cost effective. Copyright © 2010 Society of Chemical Industry Improved mechanical properties were observed for UPR‐EVA, till 0.5% EVA concentration. All formulations showed reduced shrinkage and poor chemical resistance. 0.1% of EVA1 (most branched polymer) showed improved thermal properties.
ISSN:0959-8103
1097-0126
1097-0126
DOI:10.1002/pi.2801