Mechanical properties, crystallization characteristics, and foaming behavior of polytetrafluoroethylene-reinforced poly(lactic acid) composites

Abstract

In this study, poly(lactic acid) (PLA)/polytetrafluoroethylene (PTFE) composites containing different amounts of PTFE were prepared by melt blending. The mechanical, crystallization, and foaming properties of the prepared composites were investigated. Tensile test results indicated that the mechanical properties of the composite with PTFE showed significant reinforcement and toughening effects. The average elongation‐at‐break of the composite increased by 72% compared with pure PLA. Scanning electron microscopy (SEM) showed that the PTFE elongated into fibrils during blending and formed a physical network of entanglements in the melt. Differential scanning calorimetry (DSC) also showed that PTFE had a significant nucleation effect on polymer crystals and greatly increased the crystallinity of the PLA matrix. Moreover, PTFE dramatically enhanced the melt viscosity of PLA, which was investigated by rheological tests. The injection molding foaming experiments revealed that adding 1 wt% PTFE had the most notable heterogeneous nucleation effect on foamed cells, with the cell size decreasing from 81.5 μm for neat PLA to 25.2 μm, and the cell density increasing from 1.34 × 108 cells/cm3 to 2.53 × 109 cells/cm3. POLYM. ENG. SCI., 57:570–580, 2017. © 2016 Society of Plastics Engineers

Crystallization behavior of polylactide matrix under the influence of nano‐magnetite

“…Table shows the parameters of interest such as the thermal‐transitions and the degrees of (melt) crystallinity ( X c ). From the DSC curves of the unfilled PLA and Fe 3 O 4 /PLA nanocomposites, the glass transition temperature ( T g ) of the unfilled PLA is around 60°C, which is very close to the values given in the literature . The T g of PLA was not affected by the existence of Fe 3 O 4 , and the crystallization temperature of the unfilled PLA was 130.3°C.…”

Preparation and characterization of phosphorylated graphene oxide grafted with poly(L‐lactide) and its effect on the crystallization, rheological behavior, and performance of poly (lactic acid)

“…This is because the introduction of PGO‐PLLA can produce hydrogen bond with PLA matrix and provide a large number of crystal nuclei for PLA matrix to induce rapid crystallization rate, reduce nucleation activation energy, and refine spherulite. In a certain space, the number of microcrystals increased with the addition of PGO‐PLLA, and the collision and stacking of spherulites restricted the growth of spherulites, which greatly increased the nucleation density of PLA . This result is consistent with the DSC results.…”

“…In a certain space, the number of microcrystals increased with the addition of PGO-PLLA, and the collision and stacking of spherulites restricted the growth of spherulites, which greatly increased the nucleation density of PLA. 50 This result is consistent with the DSC results. Figure 14 shows the capillary rheological curves of PLA0 and PLA2 at 185°C.…”

Thermal transitions and stability of melt mixed TiO2/Poly(L‐lactic acid) nanocomposites

“…Similar data have been reported by Li et al , who studied the nanocomposite film obtained by the addition of 1 and 5 wt% of nano‐TiO 2 to PLA. One of the possible reasons for this behavior is that TiO 2 nanoparticles may act as a heat barrier in the early stages of thermal decomposition , as well as that the incorporation of a heat‐resistant filler into the polymer matrix causes reduction in volatile degradation products, resulting in an increase of the thermal stability of the polymer composite . After completion of the decomposition process, the obtained residue of nanocomposites, presented in Table , was related with the TiO 2 content of PLLA matrix.…”