The tear resistance of the polypropylene homopolymer (HPP)/ethylene 1-octene copolymer (POE) alternating multilayered sheets, which were prepared through multilayered coextrusion, was evaluated. Polarized optical microscope (POM) photographs revealed that HPP and POE layers aligned alternately vertical to the interfaces and continuously parallel to the extrusion direction. Tear results demonstrated the conventional blends had less tear-resistant than the multilayered samples. Large plastic deformation of HPP layer occurred in the multilayered structure during the stable crack growth, causing the tear energy to increase with the number of layers increasing. The measurements of PCMW2D IR and WAXD revealed that the large plastic deformation had a direct relationship with the crystal structure and termination of micro-cracks by interface. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43298.

Ethylene–vinyl alcohol copolymer (EVOH) and linear low-density polyethylene (LLDPE) blends with 5% LLDPE grafted with 1% maleic anhydride (MAH; EVOH/LLDPE/LLDPE-g-MAH), created to increase the interfacial compatibility, were coextruded with pure LLDPE through the microlayer coextrusion technology. The phase morphology and gas-barrier properties of the alternating-layered (EVOH/LLDPE/LLDPE-g-MAH)/LLDPE composites were studied by scanning electron microscopy observation and oxygen permeation coefficient measurement. The experimental results show that the EVOH/LLDPE/LLDPE-g-MAH and LLDPE layers were parallel to each other, and the continuity of each layer was clearly evident. This structure greatly decreased the oxygen permeability coefficient compared to the pure LLDPE and the barrier percolation threshold because of the existence of the LLDPE/EVOH/LLDPE-g-MAH blend layers, and the LLDPE layers diluted the concentration of EVOH in the whole composites. In addition, the effects of the layer thickness ratio of the EVOH/LLDPE/LLDPE-g-MAH and LLDPE layers and the layer number on the barrier properties of the layered composites were investigated. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42211.

As one of the most appropriate techniques for evaluating the fracture behavior, the essential work of fracture (EWF) was introduced to investigate the fracture toughness of multilayered composites. Propylene–ethylene copolymer (CPP)/polypropylene homopolymer (HPP) alternating multilayered composites with 2–128 layers were prepared though multilayered coextrusion. Polarized optical microscopy photographs revealed that the CPP and HPP layers aligned alternately vertical to the interfaces and continuously parallel to the extrusion direction. The dichroic Fourier transform infrared spectroscopy results showed that the coextrusion sheet had a preferential orientation parallel to the melt flow direction (MD); this caused crack propagation along the blunted MD and the necking ligament section. After heat treatment, the orientation parallel to the MD could been largely eliminated, and the crack propagated in a stable manner. The specific essential work of fracture (w_e) of the multilayered composite was higher than that of the blend; this indicated a higher resistance of crack propagation. The number of layers had little effect on the toughness of the multilayered composites. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40574.

A barrier and resistance membrane consisting of alternating layers of high-density polyethylene (HDPE) and polyamide 6 (PA6) was prepared by microlayered coextrusion. The influence of phase morphology, number of layers, and compatibilizer (CP) content of HDPE/PA6-microlayered membranes on their gas barrier and water resistance properties were characterized using a scanning electron microscopy, gas in permeability, and water absorption tests. The results suggest that this special-layered structure led to significant improvement of gas barrier and water resistance properties, compared with conventional membranes. In addition, the barrier and resistance properties of microlayered membranes were obviously enhanced with increased number of layers and CP content. An optimal number of layers and CP content were determined for the improved barrier and resistance properties. POLYM. ENG. SCI., 2013. © 2013 Society of Plastics Engineers

Three kinds of polymeric blends: nylon 6/isotactic polypropylene, talc/ethylene 1-octene copolymer, and carbon black (CB)/propylene–ethylene copolymer are prepared by applying an assembly of laminating-multiplying elements (LMEs) connecting with an extruder. The morphological observations illustrate that those LMEs may not only provide biaxial stretching force on the melt, leading to the orientation of dispersed phase, but also make the distribution of those particles become more even. The tensile, barrier, or electrical properties are also investigated, respectively, and demonstrate the development of morphologies in LMEs. Results suggest that the laminating-multiplying extrusion system is a useful tool to obtain polymeric composites with specific morphologies and distribution. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers

The high density polyethylene (HDPE) and polyamide 6 (PA6) blend melts with a droplet-matrix microstructure were investigated using ultrasonic diagnosis system. The blend composition, as well as the particle size of the dispersed PA6 phase controlled by adding various amounts of the reactive compatibilizer HDPE grafted with maleic anhydride (HDPE-g-MAH), was, respectively, correlated with the ultrasonic velocity and attenuation. The results showed that ultrasonic velocity was insensitive to the particle size but varied linearly with the blend composition. However, the decrease of ultrasonic attenuation with the increasing content of HDPE-g-MAH suggested that the attenuation depended greatly on the particle size. Further investigations revealed that there was a good linear relationship between the excess attenuation and the size of the dispersed phase. Our results present that ultrasonic technique may be served as a promising technique for exploring phase morphology of polymer blends during processing. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers

The polyamide 6 (PA6)/isotactic polypropylene (iPP) in situ fibrillation composites are prepared by a novel extrusion die with an assembly of laminating-multiplying elements (LMEs). The scanning electron micrographs illustrate that the dividing-multiplying processes in LMEs elongate, break, and stabilize the dispersed PA6 phase in the iPP matrix along the flowing direction (FD). The morphology development of PA6 with different LME numbers greatly affects the rheological properties, crystalline behaviors, and mechanical properties. The dynamic rheological test performed at 195°C shows that the increased spatial restriction of the high-aspect-ratio PA6 particles increases the viscoelastic moduli, complex viscosity, and relaxation time. The crystalline analysis reveals that the heterogeneous nucleation becomes predominant and the transcrystalline morphology is observed in those samples produced by more LMEs. The tensile tests indicate that both, breaking strength and elongation, enhanced simultaneously because of the fibrillation of dispersed phase and the improvement in interfacial adhesion between the fibers and the matrix. Copyright © 2009 John Wiley & Sons, Ltd.

Poly(butylene terephthalate) (PBT)/talc composites were prepared through a single-screw extruder in the absence or presence of ultrasonic irradiation. A special exit die, which could be regarded as a capillary, was attached to the extruder to measure the effect of ultrasound on the melting temperature and pressure. The experimental results show that with the introduction of ultrasound and with its increasing intensity, the processability of the composites was improved. The morphology of the composites was also investigated by scanning electron microscopy. It was shown that ultrasonic oscillations improved the dispersion of talc in PBT and, furthermore, increased the crystallinity of PBT. Therefore, the mechanical properties were promoted through ultrasonic extrusion but decreased once the ultrasonic intensity was higher than 200 (or 150) W. This deterioration of the mechanical properties was induced by the ultrasonic degradation of PBT. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

The effects of dioctyl phthalate and inorganic filler, mica, on the sound insulation property of poly(vinyl chloride) (PVC) were investigated in this work. The stiffness and mass laws, which are the common theoretic tools to predict the soundproof properties of materials, were used to analyze the sound transmission loss (STL). The experimental results revealed that the stiffness and mass laws can describe well the sound insulation property of PVC/mica composites. The stiffness and surface density are important factors influencing the improvement of STL. With the increase of content of mica, STL and resonance frequency, f_mn, of PVC/mica composites increase. Moreover, the change of STL in the stiffness- controlled region is more obvious than that in the mass-controlled region, because the addition of mica in PVC leads to a greater increase in the stiffness. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

The relaxation processes of orientation and disorientation of melts of high-density polyethylene (HDPE) and polyamide-6 (PA6) blends compatibilized with a compatibilizer precursor (CP) of HDPE-grafted maleic anhydride (HDPE-g-MAH) were investigated in a restricted channel using real-time ultrasonic technique. The experimental results showed that the evolution of ultrasonic velocity of HDPE/PA6 blends during the orientation or disorientation processes could be described by the exponential equation from which the maximum orientation degree and relaxation time could be obtained. Subsequently, the effects of CP on the relaxation processes of orientation and disorientation were studied. In addition, the relations of the CP content and the morphology and viscosity were investigated by scanning electron microscope analysis and rheological tests. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

In an attempt to understand the relationships between the evolution of ultrasonic signal and the change of molecular structure during processing, shear-induced chain orientation and its subsequent disorientation of high-density polyethylene (HDPE) melts with different melt indices were studied using a noninvasive and nondestructive ultrasonic technique. The molecular structural development during orientation and disorientation of these melts was manifested in the ultrasonic velocity. Two models were developed to describe the relaxation processes of orientation and disorientation, respectively. The effects of shear rate and temperature on the maximal degree of orientation and the relaxation time of orientation and disorientation were also explored. These results from the ultrasonic measurements were compared with ones obtained through rheological measurements, X-ray diffraction (XRD), and infrared dichroism measurements. The experimental results indicated that the ultrasonic technique was sensitive and promising for the real-time monitoring of the evolution of molecular structure during polymer processing. POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers

The effects of compatibilizer and the number of layers on the interfacial adhesion and delamination model of coextruded microlayer samples consisting of alternating layers of high-density polyethylene (HDPE) and polyamide 6 (PA6) were studied with T-peel test. When more maleic anhydride-grafted HDPE was incorporated into HDPE layer, the interfacial delamination model changed from adhesive to cohesive failure in the case of bilayer samples. For high-layer samples, the results of X-ray photoelectron spectroscopy showed that the areal density of copolymers at the interfaces increased with increasing number of layers due to strong and durable shearing forces during microlayer coextrusion. Scanning electron microscopy observation revealed that the interfacial delamination model changed from single- to multiple-interface delamination when the number of layers increased from 16 to 32. The crack propagation included a large number of layer–layer jumps. The peel strength of microlayer samples was found to be greatly influenced by the interfacial delamination mechanisms. POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers