The effect of simulated weathering on the physicochemical properties and biodegradability of four fully biobased and potentially biodegradable agricultural mulches prepared nonwoven textile technology, consisting of randomly oriented fibers of average diameter 7-16 lm, has been investigated. Two mulches were prepared from polylactic acid (PLA) using spunbond processing, one naturally white and the other black (SB-W and SB-B, respectively), and two via meltblown processing, from 100 % PLA and a 75/25 w/w blend of PLA and polyhydroxyalkanoate [PHA; poly (3-hydroxybutyrate-co-4-hydroxybutyrate); MB-PLA and MB-PLA?PHA, respectively]. SB-W and SB-B possessed higher tensile strength than MB-PLA and MB-PLA?PHA (56.2N, 37.1N, 8.96N, and 3.90N, respectively). Simulated weathering introduced minor changes in physicochemical properties of SBs, but enhanced inherent biodegradability, yielding 68-72 % mineralization in 90 days. Simulated weathering greatly affected the physicochemical properties of the MB mulches, particularly MB-PLA?PHA, which underwent a 95 % loss of tensile strength, 32 % decrease of weightaveraged molecular weight (from 95.4 to 70.5 kDa), and breakage of microfibers, during a 21 days weatherometry cycle. Weathering accelerated the biodegradation of both MB mulches, with the time course of biodegradation and final extent of biodegradation (91-93 % in 90 days) nearly matching the value obtained for the cellulosic positive control. Fourier transform infrared spectroscopy suggested the SB and MB mulches underwent hydrolysis and photodegradative chain scission (Norrish Type II reaction). SB nonwovens may prove useful as biobased and compostable materials for multi-season mulching, and other longterm agricultural applications, such as for row covers in perennial cropping systems. MB nonwovens may be better suited for more traditional agricultural mulch applications.
The soil degradation of fully biobased agricultural mulches prepared from polylactic acid (PLA) and blends of PLA and poly3-hydroxybutyrate-co-4-hydroxybutyrate (polyhydroxyalkanoate, or PHA) using nonwoven textile technology was compared to that of a commercial biodegradable mulch film, BioTelo (Dubois Agrinovation, Waterford, Canada). The addition of PHA to PLA to the feedstock blend produced nonwovens that possessed lower tensile strength and molecular weight and increased the average fiber diameter of mulches. A meltblown (MB) nonwoven mulch prepared from a PLA-PHA 72/28 w/w blend underwent the greatest degradation, achieving a 78 % loss of tensile strength and a 25.9 % decrease of weight-averaged molecular weight during 10 and 30 week of soil burial, respectively. The mass fraction of PHA decreased during soil burial, suggesting the preferential microbial assimilation of PHA over PLA. BioTelo underwent a 29 % loss of tensile strength but no appreciable change of molecular weight for its chloroform-soluble components. In contrast, spunbond (SB) PLA mulches did not undergo any appreciable degradation during the 30 week soil burial studies. The results suggest that the MB-PLA
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.