To understand the interrelationship between the microstructure and degradation behavior of poly(lactic acid) (PLA), single-walled carbon nanotubes (CNTs) were introduced into PLA as nucleating agents. The degradation behavior of PLA-CNT nanocomposites was examined under accelerated weathering conditions with exposure to UV light, heat, and moisture. The degradation mechanism proceeded via the Norrish type II mechanism of carbonyl polyester. Differential scanning calorimetry (DSC) studies showed an increase in glass transition temperature, melting temperature, and crystallinity as a result of the degradation. However, pure PLA showed higher degradation as evidenced by increased crystallinity, lower onset decomposition temperature, embrittlement, and a higher number of micro-voids which became broader and deeper during degradation. In the PLA-CNT nanocomposites, CNTs created a tortuous pathway which inhibits the penetration of water molecules deeper into the polymer matrix, making PLA thermally stable by increasing the initial temperature of mass loss. CNTs appear to retard PLA degradation by impeding mass transfer. Our study will facilitate designing environmentally friendly packaging materials that display greater resistance to degradation in the presence of moisture and UV light.

Purpose: The purpose of this case study is to develop a lean six sigma (LSS) define–measure–analyze–improve–control (DMAIC) procedure to optimize the willingness to respond (WTR) of Louisiana-based law enforcement officials (LEO) to disasters. Design/methodology/approach: Various LSS tools were used to implement DMAIC to clearly define the problem of WTR, measure the self-reported WTR through a survey, perform statistical analysis on the measured data to identify significant variables to WTR, brainstorm issues and improvements with stakeholders, develop mitigation strategies, implement a pilot solution survey and develop control measures. Findings: Louisiana LEO showed an average of 73.9% of WTR to all disasters. Seven significant variables influenced WTR, which are prior experience, transportation, duty to organization, risk to self, conflicting roles, training and incentive pay. The results from pilot solutions showed that utilizing incentive pay, adequate training and personal protective equipment (PPE) increased WTR from 0.5% up to 16%. Originality/value: This study developed and validated a unique procedure to improve LEO WTR to disasters, providing a set of DMAIC tools and concepts that can be used by other emergency response agencies. This research was performed during the COVID-19 pandemic and after Hurricane Laura impacted Louisiana.