Degradation of PLA Biocomposites Containing Mango Seed and Organo Montmorillonite Minerals

ABSTRACT

The research of polylactic acid (PLA) packaging materials with high degradation rate is important toward high rate biodegradable packaging materials. The samples (PLA-mango seed residue-clays) were evaluated by degradation analysis (in water and in soil) followed by FTIR, NMR, SEM/EDS and Texturometer analysis. The samples degradation was more effective in water than in soil, probably due to a coupled effect of water and microbiological degradation. PLA-kernel-tegument samples degraded more than PLA-kernel samples due to the effectiveness action of kernel and tegument together in the samples’ degradation. PLA-Bofe samples degraded less than PLA-kernel-tegument and PLA-kernel-tegument-Bofe samples, PLA-Chocolate clay (Bofe and Chocolate are organo-montmorillonite clays) samples degraded more than PLA-kernel-tegument-Chocolate samples and less than PLA-kernel-tegument samples, probably due to multiples interaction among the Chocolate clay and mango components. The FTIR bands after samples hydrolytic and soil degradation presented low intensity, probably indicating materials degradation. New bands were observed after soil degradation, most likely related to accumulated soil and band displacement, indicative of samples degradation. The NMR relaxation data confirm the degradation process observed form the other techniques, observing the changes in the values of proton relaxation data for all samples, comparing the values after and before been degraded.

抽象

高降解率聚乳酸（PLA）包装材料的研究对实现高降解率的可生物降解包装材料具有重要意义. 对样品（PLA芒果籽渣粘土）进行了降解分析（在水中和土壤中），然后进行了FTIR、NMR、SEM/EDS和织构仪分析. 样品在水中的降解比在土壤中更有效，可能是由于水和微生物降解的耦合作用. 由于果仁和被皮在样品降解过程中的有效作用，PLA核被皮样品比PLA核样品降解更严重. PLA-Bofe样品的降解程度低于PLA核和PLA核的Bofe样品，PLA巧克力粘土（Bofe和巧克力都是有机蒙脱石粘土）样品的降解程度大于PLA核的巧克力样品，小于PLA核的样品，可能是由于巧克力粘土和芒果成分之间的多重相互作用. 样品水解和土壤降解后的FTIR谱带强度较低，可能是材料降解的标志。在土壤退化后观察到新的带，很可能与累积的土壤和带位移有关，表明样品退化. 核磁共振弛豫数据证实了其他方法观察到的降解过程，观察了所有样品的质子弛豫数据值的变化，并比较了降解前后的值.

KEYWORDS:

• Degradation
• PLA
• mango seed
• organo-montmorillonite

关键词:

• 降解
• 芒果籽
• 有机蒙脱土

Acknowledgments

The authors acknowledge the support for Brazilian Agricultural Research Corporation (EMBRAPA) and Mineral Technology Center (CETEM).