Abstract
Abstract In spite of the high electrical conductivity of carbon nanotube (CNT), its tendency to aggregate and expensive cost in fabricating aerogel, foams, and porous materials remains a problem. Therefore, we described a simple and feasible way to design light-weight, high electrically conductive, and cost-efficient polylactic acid (PLA)/CNT foams. The branched PLA (BPLA) resin with excellent melt elasticity and foamability was induced by nucleophilic ring-opening reaction of epoxy-based acrylic/styrene copolymer and PLA. After that, BPLA/CNT composites and foams were prepared by melt-mixing and supercritical carbon dioxide foaming technology, respectively. The thermal, electrical, and foaming properties were studied. The resultant BPLA/CNT foam possessed a low density of 0.174 g/cm3 and high crystallinity of 3.03%. An improvement of the oriented structure of CNT induced by cell growth in BPLA matrix increased the conductivity of the foam up to 3.51 × 104 Ω/m. The proposed foaming materials provided a way for designing and preparing high performance CNT products.
Highlights
Because of its desirable electrical conductivity, carbon nanotube (CNT) has been used in electrical materials for many purposes, which includes conducting materials [1,2], Among the various polymeric matrixes, bio-based and bio-degradable polylactic acid (PLA) have attracted many interests for structural and functional applications as an alternative to conventional petroleum-based plastics [18,19,20,21]
We focused on developing a simple strategy for fabricating PLA/CNT foams
Sasaki et al provide that α crystalline with two antiparallel-oriented 103 helical chain segments in every orthorhombic cell unit would form at a crystallization temperature of 120°C [37,38], whereas the imperfect α′ crystalline with hexagonal cell unit would form below 100°C [39]
Summary
Because of its desirable electrical conductivity, carbon nanotube (CNT) has been used in electrical materials for many purposes, which includes conducting materials [1,2], Among the various polymeric matrixes, bio-based and bio-degradable polylactic acid (PLA) have attracted many interests for structural and functional applications as an alternative to conventional petroleum-based plastics [18,19,20,21]. Conductive and light-weight branched PLA-based CNT foams 97. The electrical, mechanical, and thermal properties of foamed PLA materials can be designed by manipulating the structure [24,25,26]. An oriented CNT structure in foams has shown great potential applications in tissue engineering, separation, and environmental protection owing to their tunable foaming structure and enhanced mechanical properties along the oriented direction [29,30,31]. Because of the poor rheological properties of linear PLA (LPLA), it is still a challenge to fabricate foams with light-weight, which could not further give rise to oriented and even electrically connecting individual CNT on cellular walls. The branching reaction could change the molecular structure and increase the molecular weight by producing branching and cross-linking structures, which improved its viscoelasticity performance [32]
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