Preparation of ultrafine wheat straws with co-milling and its incorporation for biodegradable mulch film production with enhanced performance

Although polybutylene adipate-co-terephthalate (PBAT)-based biodegradable mulch films are potential in replacing the traditional polyethene ones with increased cultivation sustainability, some practical issues including the high price and low performance still need to be resolved. Here, ultrafine powder of zero-cost straws was doped into PBAT-based films due to its toughness and ultraviolet (UV)-resistance. The powder was prepared by co-milling with a few calcium carbonates, which act as not only a friction agent to greatly increase the milling efficiency, but also an anti-blocking agent during film blowing. Slight changes in rheological and thermal behaviors of the composite films were observed with the introduction of this ultrafine filler, thus have no crucial effect on film processing. However, the UV-blocking and aging-resistant properties of the films were both enhanced, which is quite essential to a mulch film for long-term cultivation. Meanwhile, the mechanical and the water vapor barrier properties were also slightly increased with the addition of < 10 wt% fillers. It is noted that the films can meet the standards of biodegradable mulch films even after 80.9-h UV irradiation. Besides, the cost is estimated to reduce over 8.14%, which makes it quite feasible for mulching in the future.