ABSTRACT
Solid polymer electrolytes (SPEs) have emerged as a promising avenue for developing flexible lithium-ion batteries. However, the low ionic conductivity of polymers remains a primary challenge that has been the subject of intensive research efforts in recent years. In this work, polyethylene oxide (PEO), polyvinyl alcohol, lithium perchlorate (LiClO4), and graphene functionalized with polyethylene glycol (FGO) have been used to prepare SPE/FGO electrolytes by casting solution technique. X-ray diffraction (XRD) and differential scanning calorimetry (DSC) confirmed the reduction of SPE crystals and the increase of amorphous phases. The results demonstrated that the presence of functionalized graphene had an effective role in reducing crystallinity. Furthermore, the thermal and mechanical stability of the samples were corroborated through thermogravimetric analysis (TGA) and tensile tests, respectively. Notably, the samples exhibited adequate ionic conductivity at room temperature, with the highest ionic conductivity of 5.2 × 10-5 S·cm-1 observed for 2%wt of FGO in SPE (SPE/FGO(2)).
ABSTRACT
In this paper, different nanocomposites made of a polymer blend (80% of PDLLA and 20% of PCL in w/w) and various amounts of a sol-gel derived bioactive glass nanoparticles (0, 1, 3 and 6wt%) were prepared using a solvent-evaporation technique. The morphology, mechanical properties and osteoblastic cell behaviors of the nanocomposites were evaluated. According to the early results, addition of bioactive glass nanoparticles to the polymer matrix reduced the tensile and flexural strength because of a non-uniform distribution of the nanoparticles. Thus, a homogeneous dispersion was obtained by surface modification of the glass nanoparticles using (3-aminopropyl)triethoxysilane as a coupling agent. The results showed that the tensile and flexural strength of the nanocomposite were improved by the nanoparticle functionalization, however the glass content was a crucial factor. The maximum tensile and flexural strength values of 38MPa and 94MPa were obtained for the polymer matrix loaded with 3wt% of the modified nanofiller and further increase of filler content led to sever agglomeration and hence a reduction of the mechanical properties. The obtained mechanical properties are favorable for anterior cruciate ligament reconstruction screws. Besides, the results of cell culture using human osteoblastic cells illustrated better cell attachment and cell growth of the nanocomposites compared to the neat polymer blend.
Subject(s)
Nanocomposites , Anterior Cruciate Ligament Reconstruction , Biocompatible Materials , Dioxanes , Glass , Materials Testing , Polyesters , Tensile StrengthABSTRACT
In this study, polymer blends comprising poly(D/L) lactic acid (PDLLA) and 0-30wt% polycaprolactone (PCL) was prepared by a solvent-evaporation technique. The effect of PCL content on the dynamic-mechanical properties and tensile and flexural characteristics of the blends was evaluated. The creep and stress relaxation behaviors were also determined and using various known models such as power law, Burgers model and Weibull distribution equation. The results showed that by increasing the PCL content from 10 to 30wt%, the yield stress and flexural strength decreased from 47MPa to 26MPa and 72MPa to 29MPa respectively. In addition to tensile and flexural strength, the elastic modulus of neat PDLLA declined with increasing the PCL content, whereas the elongation or the strain percentage at the break point increased considerably. Biphasic regions were observed in the microstructures of the blends, indicating the immiscibility of PCL in PDLLA matrix. However, the PCL spherulites with an average particle diameter of 100nm to 5µm were homogeneously dispersed in PDLLA phase even at high PCL concentrations. Moreover, the microstructures of the fractured surfaces of the polymers confirmed that PDLLA with a brittle fracture behavior tends toward a soft fracture behavior when it is blended with PCL. The dynamic-mechanical tests indicated that the damping energy and dissipative ability of PDLLA improve by adding PCL. Moreover, Tg of neat PDLLA by adding of 10, 20 and 30wt% decreases from 67.3 to 66.2, 65.1 and 63.5°C respectively. Increasing in the recovered viscoelastic strain due to the addition of PCL was also experienced which can be attributed to the presence of large volumetric backbone of PCL chains as well as easy movement of them in the matrix. The results of modeling studies showed a good correlation between the experimentally obtained data.
