A correlation between morphology and mechanical performance of injected‐molded PE/EVA/clay nanocomposites: Insight into phase miscibility and interfacial phenomena

Abstract

In this study, the correlations between the mechanical performance and structural properties of injected‐molded polyethylene (PE)/ethylene‐vinyl acetate copolymer (EVA)/nanoclay (NC) nanocomposites are investigated by revisiting the interfacial phenomena and miscibility state of the component pairs. The effects of different parameters including the injection molding temperature, mixing sequence in melt‐compounding process, blend composition, and nanoclay loading are studied. A great complexity arises in the filling and cooling process of the injected‐molded parts owing to the phase behavior of the polyolefin blend, crystallization, and morphological changes. The injection molding temperature positively influences the elastic modulus, tensile strength and impact strength of PE/EVA/NC systems through the improvements in the PE/EVA partial miscibility, mutual solubility, and interfacial interactions of PE/clay and PE/EVA pairs. By applying a two‐step mixing process before the injection molding, more nanoclay stacks with smaller thicknesses and larger clay interlayer spacing are formed. The stronger pinning effect of nanoparticles in the second mixing sequence retards the phase separation phenomenon of PE/EVA blend during the cooling stage. As a result of improved mutual PE/EVA solubility, the elastic modulus and tensile strength decrease and the impact resistance increases in the PE‐rich systems. On the other hand, an opposite trend for these properties is found for the EVA‐rich systems.

Design of Novel POB/h-BN Co-Filled PTFE Composites with Enhanced Thermal–Mechanical Properties

“…The cross-linked hybrid structure with some regular pores in Figures 8f and 9d dramatically enhanced the phonon scattering. In addition, the uniform distribution of the anisotropic orientation of h-BN flakes had the pinning effect and further promoted the improvement of thermal stability and mechanical reliability [44,45]. Therefore, the synergetic effect of the POB and h-BN multi-component fillers improved the comprehensive properties of PTFE-based composites.…”

“…The composite with 25 wt.% POB and 5 wt.% h-BN showed a cross-linked structure with regularly distributed pores, which was further conducive to higher thermal stability and thermal conductivity (see Figure 8f and Table 3). In addition, the h-BN as the second phase possessed the pinning effect of phase boundaries, which enhanced the mechanical properties [43,44]. SEM images of the fracture surface for PTFE composites filled with different h-BN contents are shown in Figure 9.…”

Research on torsional laminated extrusion for improving the permeability and mechanical properties ofHDPE/PA6composite for typeIVstorage tank liners

“…[6][7][8][9][10] However, the properties of these liner material pose critical challenges for enhancing the hydrogen storage density and properties of the aforementioned tanks, including the barrier properties (for HDPE) and mechanical properties as well as machinability (for PA6 as well). 8,[11][12][13] Previous work [14][15][16][17][18] have indicated that the free-volume and permeability path of liner materials are the key factors that affect their gas barrier properties. Thus, effective measures 13,[19][20][21][22] to improve the barrier properties involve employing functional fillers with highbarrier properties or optimizing the aggregation structure.…”

“…8,[11][12][13] Previous work [14][15][16][17][18] have indicated that the free-volume and permeability path of liner materials are the key factors that affect their gas barrier properties. Thus, effective measures 13,[19][20][21][22] to improve the barrier properties involve employing functional fillers with highbarrier properties or optimizing the aggregation structure.…”

“…However, it is challenging to maintain the original effectiveness of multilayer materials at the head of the injection molding, weld of the welding, and fusion line of the blow molding. 13 Therefore, it is necessary to directly obtain the efficiency gains of blended composites. In this study, we report micro-nano torsional laminated extrusion (MNTLE) to improve the composite orientation and reduce inter-crystalline defects through dividing, laminated thinning, and biaxial stretching of the melt with a strong drag flow field.…”