Abstract
Development of eco-friendly polymer foams is an urgent research topic because of the serious environmental pollution caused by trash heaps and the time-release of harmful gases. Polymer PVC foam using azodicarbonamide as a chemical foaming agent has been highly requested for further improvement due to the residual ammonia gas that continuously leaks out. Here, we demonstrate an effective and costless process for the reduction of releasing ammonia from PVC foams using the overcoat technology of deodorants. We have selected four candidate materials, gelite, zeolite, terra alba, and fumed silica as original materials for the deodorant of ammonia, and they showed an ammonia deodorization rate (ADR) of over 80% without any treatment except the fumed silica. When we over-coated the UV-curing agent mixed deodorants on the PVC foams (thickness ~300 µm), the ADR of the terra alba and zeolite complex foams was remarkably higher than 90%, however, the specific gravity and chromaticity were not changed within 20%. This indicates that our developed process using deodorant layer for ammonia reduction has a high potential for the production of eco-friendly polymer foams.
Highlights
Polymer foams have many useful attributes such as flexibility, low density, impact resistance, and heat transfer capacity compared with conventional rigid polymers [1]
To test the deodorization of time-releasing ammonia gas, the foam over-coated by the deodorant was sealed in the Tedlar bag filled with nitrogen gas and placed under 25 and 80 ◦ C
We used six different deodorants, gelite, HCl-gelite, zeolite, terra alba, and hydrophobic/hydrophilic fumed silica, which have been recognized by a good deodorizing ability [21,28,30]
Summary
Polymer foams have many useful attributes such as flexibility, low density, impact resistance, and heat transfer capacity compared with conventional rigid polymers [1]. The deodorant materials mixed with polymer foams were not effective to deodorize the residual gases compared to the original materials [30]. Another method proposed is dehydrogenating the gaseous formamide to hydrogen cyanide (HCN) [31]. An interesting approach to clay coating on porous foams has been introduced for an alternative fire retardant [33,34], which inspired us to hybridize inorganic deodorants and polymer foams. We have probed organic-inorganic hybrid deodorants, which reduce the releasing ammonia gas captured inside the foam.
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