Hydrolytic Degradation of 3D-Printed Poly (Lactic Acid) Structures

Hydrolytic degradation of commercially available 3D printing filament, i.e. poly (lactic acid) with broad molecular weight distribution was induced by incubating 3D-printed parts in deionized water at 3 temperatures. Small changes in orthogonal dimensions occurred due to relaxation of printing stresses, but no mass or volume loss were detected over the time-frame of the experiments. Molecular weight decreased while polydispersity remained constant. The most sensitive measure of degradation was found to be nondestructive, small-amplitude oscillatory tensile measurements. A rapid decay of tensile storage modulus was found with an exponential decay time constant of about an hour. This work demonstrates that practical monitoring of commercially available PLA degradation can be achieve with linear viscoelastic measurements of modulus.

Asymmetric bis-salicylaldiminato binuclear titanium complexes for ethylene polymerization and copolymerization

Polyolefins with high molecular weight and broad molecular weight distribution have attracted great attention due to their ease of processing and wide applications. In this paper, methylene-bridged asymmetric disalicylaldimine ligands...

Synthesis of Carbon Nanoparticles via Co-Pyrolysis of Waste Slop Oil and Ferrocene

Co-pyrolysis of slop oil with ferrocene was carried out to convert waste of petroleum into carbon nanoparticles (CNPs). Since slop oil is a mixture of hydrocarbons (HCs) with broad molecular weight distribution, it could be simply fractionated into some certain fractions by batch distillation. Distillate containing hydrocarbons with small molecules was mainly focused as an alternative carbon source for synthesis of CNPs. A two-stage furnace was employed for evaporating a mixture of distillated slop oil and ferrocene at 200 °C in the 1st stage of the furnace and then formation of CNPs at 900 °C could be observed in the 2nd stage. Laboratory-grade ferrocene was mixed with slop oil with a designated weight-ratio of 1:2. Microscopic analyses based on SEM and TEM micrographs reveals that CNPs obtained from distillated slop oil mostly consist of bundles of multi-walled carbon nanotubes (MWCNTs) with nominal diameters of 20-50 nm. Raman spectroscopic analyses of the synthesized CNPs exhibit the notably high value of IG/ID, suggesting that the synthesized CNPs preferably consist of graphitic nanostructure. Moreover, TGA analysis shows that 39.8 and 32.9 wt% of Fe contents exist in the CNP samples synthesized from original slop oil and distillated slop oil, respectively.