Impact of Nanoclays on the Biodegradation of Poly(Lactic Acid) Nanocomposites

Abstract

Poly(lactic acid) (PLA), a well-known biodegradable and compostable polymer, was used in this study as a model system to determine if the addition of nanoclays affects its biodegradation in simulated composting conditions and whether the nanoclays impact the microbial population in a compost environment. Three different nanoclays were studied due to their different surface characteristics but similar chemistry: organo-modified montmorillonite (OMMT), Halloysite nanotubes (HNT), and Laponite ® RD (LRD). Additionally, the organo-modifier of MMT, methyl, tallow, bis-2-hydroxyethyl, quaternary ammonium (QAC), was studied. PLA and PLA bio-nanocomposite (BNC) films were produced, characterized, and used for biodegradation evaluation with an in-house built direct measurement respirometer (DMR) following the analysis of evolved CO 2 approach. A biofilm formation essay and scanning electron microscopy were used to evaluate microbial attachment on the surface of PLA and BNCs. The results obtained from four different biodegradation tests with PLA and its BNCs showed a significantly higher mineralization of the films containing nanoclay in comparison to the pristine PLA during the first three to four weeks of testing, mainly attributed to the reduction in the PLA lag time. The effect of the nanoclays on the initial molecular weight during processing played a crucial role in the evolution of CO 2 . PLA-LRD5 had the greatest microbial attachment on the surface as confirmed by the biofilm test and the SEM micrographs, while PLA-QAC0.4 had the lowest biofilm formation that may be attributed to the inhibitory effect also found during the biodegradation test when the QAC was tested by itself.

Effects of halloysite nanotube on the performance of natural fiber filled poly(lactic acid) composites

“…HNT, Al 2 Si 2 O 5 (OH) 4 ·2H 2 O is chemically similar to the kaolinite group of clay, and exhibits a hollow nanotubular structure with a large aspect ratio similar to that of CNT . Moreover, HNT that has almost no surface charge and does not require modification for homogenous dispersion in polymer matrix has been used as nanofiller for some polymers such as poly(propylene), vinyl ester, polyamide, poly(vinyl chloride), epoxy, and natural rubber for improvement some properties like mechanical, thermal, crystallinity, and fire resistance . Furthermore, compared to CNT, HNT is utilized in drug delivery, genes delivery, and biomedical applications since it consists of only trace amount of heavy metals, which is much lower than the highest limits of restriction on harmful substances according to of European standards .…”

Evaluation of biodegradation of polylactic acid mineral composites in composting conditions

“…On the other hand, the 80/20 PLA/Cloisite and 80/20 PLA/NTM test samples accounted for 100% sample mineralization after 30–40 days and seemingly continued to show increasing mineralization until the termination of the test. Negative mineralization values were observed for neat PLA from day 7 to day 18, which, according to one study, might be attributed to the slightly superior barrier property of the PLA film compared to the other two films. The mineralization levels observed in the 80/20 PLA/Cloisite and 80/20 PLA/NTM test samples suggest positive priming effects, which we attribute to the elevated nutrients present in these additives (Table ) …”

Preparation and characterization of polymethacrylamide/halloysite composites

“…[7,8] Biocompatibility, natural abundance, and unique surface morphology of halloysite attracted attention and also have a significant role for the preparation of high-performance polymer composites. [6,9,10] HNT has almost no surface charge and does not require organic modification for adequate dispersion. [11,12] However, HNT has shown improved dispersion during processing and enhanced mechanical and thermal properties.…”

“…[11,12] However, HNT has shown improved dispersion during processing and enhanced mechanical and thermal properties. [10] The tubular morphology and nanoscale diameter of halloysite are important in reinforcing polymer composites. Halloysite-polymer composites are used in a variety of potential applications such as tissue engineering scaffolds, wound dressing materials, bone implants, cosmetic applications, drug delivery carrier, and cancer diagnosis materials.…”