1. Scope

Keywords

Rationale

The proposed Standard addresses limitations of ISO EN17033 and ISO 23517 standards which are written exclusively for the types of polymers not designed to rely on natural environmental exposure to initiate their biodegradation. Examples of such polymers include but not limited to polyesters, their blends and their blends with starches. The proposed Standard is written to include the families of polymers designed to rely on natural weathering-induced chemical modification, which becomes a prerequisite for the biological degradation. Therefore, the proposed standard requires a pre-exposure step, which is defined as exposure of films to anticipated natural conditions (temperature, and radiant exposure) and duration of time. The pre-exposure step could be based on natural or accelerated weathering, but in the latter case the data demonstrating correlation to the natural exposure to exclude conditions not achievable in nature shall be provided. With the proposed change, the expanded family of materials for mulch film applications would include polyolefins and their blends with natural polymers and/or suitable biodegradable polymers. Chemical (or abiotic) modification of polyolefins can be driven catalytically at natural conditions with environmentally safe and soil beneficial catalytic materials. Soil biodegradable mulch films based on modified polyolefins could provide the best option to satisfy required in-use properties, ease of handling, affordability and environmental safety. These new types of polymers could meet the timeline for soil biodegradation defined by ISO 23517 and EN17033 as 2 years but would be metabolized with higher Carbon Use Efficiency (CUE) leading to lower conversion of polymeric carbon into CO2, its higher accumulation in microbial biomass, regeneration of Soil Organic Matter (SOM) and improved carbon storage. To address differences in performance and degradation of base films vs fully formulated commercial films, unlike in EN 17033 and ISO 23517, this standard requires testing the mulch film formulation in its final form, including all required additives, fillers and colorants.