Tao Qiang

Polylactide (PLA) has been regarded as one of the most promising bio-based, environmentally-friendly polymers. The products derived from PLA will degrade into CO2 and H2 O ultimately after being wastes. To this extent, PLA is the really sustainable synthetic polymers, due to its nature-to-nature loop within life cycle. However, inherent brittleness, poor heat resistance, slow crystallization rate and high cost, have limited pure PLA and its composites’ potential applications. Carbon nanotubes (CNT) is one kinds of one-dimensional nano-materials with hollow structures composed of only hybrid sp2 C-C bonds. CNT is identified as the most preferred candidate for space elevators, due to its excellent mechanical properties and electrical conductivity. CNT/PLA blends will exert synergistic effects of their individual component, bring breakthroughs in their structures and various properties, and open up potential application scenarios for the resultant composite materials. In this review, recent advances on fabrication methods, structure manipulation, property optimization and application scenarios of CNT/PLA composites were summarized. Especially, the effects of CNT content and pretreatment methods on the microstructures and properties of the resultant PLA composites were focused on in this review. Also, future prospective of CNT/PLA composite materials were addressed.

Background: The usage status, waste electrical and electronic equipment (WEEE) related to the smartphones of on-campus engineering students should be studied. Furthermore, the correlations between their smartphone profiles with energy consumption and environmental knowledge should be understood make measures improve their environmental behaviors. Methods: Pro-environmental behavior and smartphone uses of the on-campus engineering undergraduates in Xi’an, China, were investigated with a self-designed questionnaire anonymously. The energy-saving activities they participated in and their e-waste treatment patterns were analyzed. Results: Most of the respondents had a smartphone with large screen and high battery capacity, which also had long standby/usage time and frequent charging. Average daily power consumption of one smartphone was estimated to be 6.475 Wh. The surveyed undergraduate students changed their smartphones frequently, which produced large quantities of WEEE annually. Conclusion: Most on-campus students treated their waste smartphones in the proper ways. However, some of them were short of environmental knowledge about their smartphones. Some measures were suggested to improve their environmental concerns. The findings will help the on-campus engineering undergraduates in China to use their smartphones rationally and to deal with their waste smartphones appropriately.

In this study, a life cycle assessment (LCA) was used to investigate the environmental benefits of using styrene-butadiene-styrene (SBS) to modify polylactide (PLA)-based wood plastic composites (WPCs), with a process-based and input–output hybrid model. The results showed that one metric ton of the SBS-modified WPCs required 1.93 × 10⁸ kJ of energy (Sample 2) and 46 m³ of water (Sample 4), and that it could produce 42.3 kg of solid waste (Sample 2) during its cradle-to-gate life cycle phases. The environmental impact load (EIL) and photochemistry oxidation potential (PCOP) accounted for the largest share, while the eutrophication potential (EP) took the smallest one. The total EIL index of Samples 1, 2, 3, and 4 added up to 1.942, 1.960, 1.899, and 1.838, respectively. The SBS-modified WPCs were found to be more environmentally friendly than their unmodified counterparts when they had the same or higher wood fiber (WF) content. SBS was viable to toughen the PLA-based WPCs from an environmental perspective. This cradle-to-gate LCA is likely to help optimize the manufacturing process and mitigate environmental impacts for the natural fiber-reinforced polymer biocomposites.

Scientific discovery evolves from the experimental, through the theoretical and computational, to the current data-intensive paradigm. Materials science is no exception, especially for computational materials science. In recent years, great achievements have been made in the field of materials science and engineering (MSE). Here, we review the previous paradigms of materials science and some classical MSE models. Then, our data-intensive MSE (DIMSE) model is proposed to reshape future materials innovations. This work will help to address the global challenge for materials discovery in the era of artificial intelligence (AI), and essentially contribute to accelerating future materials continuum.

Modifying bio-based degradable polymers such as polylactide (PLA) and poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) with non-degradable agents will compromise the 100% degradability of their resultant composites. This work developed a facile and solvent-free route in order to fabricate 100% bio-based and degradable ternary cellulose/PHBV/PLA composite materials. The effects of ball milling on the physicochemical properties of pulp cellulose fibers, and the ball-milled cellulose particles on the morphology and mechanical properties of PHBV/PLA blends, were investigated experimentally and statistically. The results showed that more ball-milling time resulted in a smaller particle size and lower crystallinity by way of mechanical disintegration. Filling PHBV/PLA blends with the ball-milled celluloses dramatically increased the stiffness at all of the levels of particle size and filling content, and improved their elongation at the break and fracture work at certain levels of particle size and filling content. It was also found that the high filling content of the ball-milled cellulose particles was detrimental to the mechanical properties for the resultant composite materials. The ternary cellulose/PHBV/PLA composite materials have some potential applications, such as in packaging materials and automobile inner decoration parts. Furthermore, filling content contributes more to the variations of their mechanical properties than particle size does. Statistical analysis combined with experimental tests provide a new pathway to quantitatively evaluate the effects of multiple variables on a specific property, and figure out the dominant one for the resultant composite materials.

A solvent-free route was developed to fabricate 100% biobased, renewable, and degradable polylactide (PLA) composites reinforced with ball-milled celluloses. The results show that the original pulp cellulose fibers were modified to partial amorphization through 30-min ball milling. Filling the ball milled celluloses into PLA increased the tensile modulus for the resultant cellulose/PLA composite materials, while decreased their tensile strength and impact resistance. This method can be used to access the cost-efficient PLA-based composite materials with tunable mechanical properties. The variation analysis shows that filling content contributed more to the variations of their mechanical properties than that particle size did.