Performance and Degradation of Nonwoven Mulches Made of Natural Fibres and PLA Polymer-Open Field Study

Effect of Biodegradable Nonwoven Mulches from Natural and Renewable Sources on Lettuce Cultivation

Numerous research showed that mulching with conventional agro foils elevates soil temperature and promotes plant growth, but negatively influences soil health and brings environmental concerns. Most of the published research on nonwoven mulches for plant cultivation includes nonwoven fabrics produced by extrusion processes providing nonwoven fabric structures similar to films. A limited number of studies investigate the impact of nonwoven mulches produced by a mechanical process on the cards and bonded by needling on plant cultivation. For this study, nonwoven mulches of mass per unit area of 400 g m-2 made from jute, hemp, viscose (CV), and polylactide (PLA) fibers were produced on the card bonded by needle punching. The field experiment was conducted two consecutive years in a row, in spring 2022 and 2023, by planting lettuce seedlings. The nonwoven mulches maintain lower temperatures and higher soil moisture levels compared to agro foil and the control field. The fibrous structure and their water absorption properties allow natural ventilation, regulating temperatures and retaining moisture of soil, consequently improving soil quality, lettuce yield, and quality. The fiber type from which the mulches were produced, influenced soil temperature and humidity, soil quality, and lettuce cultivation. The nonwoven mulches were successful in weed control concerning the weediness of the control field. Based on the obtained results, the newly produced mulches are likely to yield better results when used for the cultivation of vegetables with longer growing periods. Newly produced biodegradable nonwoven mulches could be an eco-friendly alternative to traditional agro foil, minimizing environmental harm during decomposition. The obtained results suggest that the newly produced mulches would be even more suitable for growing vegetables with longer growing seasons.

Ductile Copolyesters Prepared Using Succinic Acid, 1,4-Butanediol, and Bis(2-hydroxyethyl) Terephthalate with Minimizing Generation of Tetrahydrofuran

Poly(1,4-butylene succinate) (PBS) is a promising sustainable and biodegradable synthetic polyester. In this study, we synthesized PBS-based copolyesters by incorporating 5-20 mol% of -O2CC6H4CO2- and -OCH2CH2O- units through the polycondensation of succinic acid (SA) with 1,4-butanediol (BD) and bis(2-hydroxyethyl) terephthalate (BHET). Two different catalysts, H3PO4 and the conventional catalyst (nBuO)4Ti, were used comparatively in the synthesis process. The copolyesters produced using the former were treated with M(2-ethylhexanoate)2 (M = Mg, Zn, Mn) to connect the chains through ionic interactions between M2+ ions and either -CH2OP(O)(OH)O- or (-CH2O)2P(O)O- groups. By incorporating BHET units (i.e., -O2CC6H4CO2- and -OCH2CH2O-), the resulting copolyesters exhibited improved ductile properties with enhanced elongation at break, albeit with reduced tensile strength. The copolyesters prepared with H3PO4/M(2-ethylhexanoate)2 displayed a less random distribution of -O2CC6H4CO2- and -OCH2CH2O- units, leading to a faster crystallization rate, higher Tm value, and higher yield strength compared to those prepared with (nBuO)4Ti using the same amount of BHET. Furthermore, they displayed substantial shear-thinning behavior in their rheological properties due to the presence of long-chain branches of (-CH2O)3P=O units. Unfortunately, the copolyesters prepared with H3PO4/M(2-ethylhexanoate)2, and hence containing M2+, -CH2OP(O)(OH)O-, (-CH2O)2P(O)O- groups, did not exhibit enhanced biodegradability under ambient soil conditions.

Impact of Polylactic Acid Fibers in Cellulose Nonwoven Mulch Blends on Biodegradability and Performance-An Open Field Study

The performance and degradation of nonwoven mulches made from viscose, jute, hemp fibers, and their blends with PLA fibers, subjected to field conditions, are investigated. This research explores the possible substitution of traditional agricultural polyethylene mulching agro foil with environmentally friendly biodegradable nonwoven mulches produced from blends of jute, hemp, and viscose fibers along with PLA fibers. The nonwoven mulches underwent a ten-month exposure to field conditions, showing varied degradation. The jute and hemp nonwoven mulches degraded completely within the test period, whereas their blends with PLA fibers exhibited slowed degradation. This study indicated that PLA fibers in blends with jute, hemp, and viscose mulches slowed degradation, impacting their structural integrity and tensile properties. The tensile properties of nonwoven mulches blended with 20% of PLA fibers increased the breaking forces after field exposure. Observations on structural changes through microscopy highlighted the structure maintenance in jute and hemp blends due to the non-degraded PLA fibers, contrasting the complete degradation of 100% jute and hemp mulches. A microscopic analysis revealed alterations in the fiber structure and density changes, particularly in viscose mulches and their blends with PLA fibers. Soil temperature variations were observed under different mulches; e.g., agro foil consistently exhibited higher temperatures compared to nonwoven mulches. Notably, the hemp and jute/PLA blend mulches showed slightly elevated temperatures, while the viscose-based mulches consistently revealed the lowest temperatures. Regarding soil moisture, the nonwoven mulches generally maintained higher moisture levels compared to the control field and agro foil from June to October. These findings suggest that nonwoven mulches effectively preserved soil moisture during critical growth periods, potentially positively impacting plant growth. The weed suppression capabilities varied among mulches, with hemp mulch initially displaying the lowest suppression ability in the first six months. The addition of 20% of PLA fibers in mulch blends with viscose, jute, and hemp notably improved the weed control capabilities. Understanding the impacts of field conditions on newly produced nonwoven mulches is crucial for optimizing mulch selection in agricultural practices to enhance soil conditions and weed management.