ABSTRACT
In this study, a fully biodegradable ultra-light poly(lactic acid)/silicon dioxide (PLA/SiO2) aerogel nanocomposite with ultra-low thermal conductivity was successfully fabricated. PLA used was a produced from lactic acid, where the lactic acid has been produced from carbohydrates. The rheological properties of PLA were enhanced by diphenylmethane diisocyanate (MDI). The foaming properties, cell density, cell size uniformity, mechanical properties and thermal conductivity and thermal diffusivity of PLA were further improved by SiO2 aerogel, and finally the ultra-low density foamed material was prepared by supercritical CO2. The density of PLA foam can be as low as 0.02 g/cm3 and the thermal conductivity as low as 0.02628 W/m·K. The PLA-based composites can be used in many fields such as thermal insulation, vibration damping and packaging, and can be fully biodegradable and sustainable throughout their life cycle, which meets the global trend of energy saving and emission reduction.
Subject(s)
Construction Materials , Gels/chemistry , Polyesters/chemistry , Silicon Dioxide/chemistry , Viscoelastic Substances/chemistry , Chemical Phenomena , Construction Materials/analysis , Mechanical Phenomena , Nanocomposites , Porosity , Rheology , Spectrum Analysis , Thermal ConductivityABSTRACT
Pristine multiwalled carbon nanotubes (MWNTs) and zirconia-coated multiwalled carbon nanotubes (ZrO(2)/MWNTs) by isothermal hydrolysis and the traditional chemical precipitation method have been dispersed into polyvinylidene fluoride (PVDF) copolymer by solution mixing in N,N-dimethylformamide (DMF). The effect of ZrO(2)-coated MWNTs on morphological properties, electrical properties, and flame-retardant behavior has been studied in comparison with virgin PVDF and PVDF/MWNTs nanocomposites. Due to the improved dispersion of the coated nanotubes, the incorporation of 3 wt % of ZrO(2)-coated MWNTs leads to an increase of the thermal stability and dielectric properties and a decrease of the peak heat-release rate.
ABSTRACT
The aim of this research was to recycle waste rubber tires by using powdering technology and treating the waste rubber tire powder with bitumen. It has been proven that the elongation at break, thermal stability and processing flowability of composites of polypropylene (PP), waste rubber tire powder (WRT) and bitumen composites are better than those of PP/WRT composite. A comparative study has been made to evaluate the influence of bitumen content and different compatibilizers on the properties of PP/WRT/bitumen composites, using a universal testing machine (UTM), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and a capillary rheometer. The results suggested that the properties of PP/WRT/bitumen composites were dependent on the bitumen content and the kind of compatibilizer used.
