Mechanical Properties and Morphology of LDPE/PP Blends

Two types of polypropylene (PP) with different molecular structure, namely, homogeneous PP (PPH) and PP block‐copolymer (PPC), were blended with a long chain, branched, low density polyethylene (LDPE) in a twin screw extruder and then injection moulded into test specimens; the mechanical properties and morphology of the blends are reported. The tensile strength, elastic modulus, flexural strength, and flexural modulus of the blends increased monotonically with increasing PP content, although exhibiting a slightly negative deviation from the rules of mixtures due to the relatively poor compatibility of the components, which caused the blends to separate into individual phases. Comparatively, these mechanical properties of the LDPE/PPH blend were much higher than that of the LDPE/PPC blend, which was attributable mainly to the fact that the mechanical properties of neat PPH are stronger than that of neat PPC. With respect to the impact strength of the blends, a maximum value appeared in LDPE/PPH blends when PPH content was about 20% and also in LDPE/PPC blends when PPC content was about 40%.     

Morphology,Rheology, and Mechanical Properties of Polylactide/Poly(Ethylene-co-octene) Blends

Polylactide (PLA)/poly(ethylene-co-octene) (POE) blends containing ethylene-glycidyl methacrylate copolymer (EGMA) as a compatibilizer were prepared by melt blending. An immiscible, two-phase structure with POE dispersed in the PLA matrix was observed by scanning electron microscopy. It was found that the POE particle size was significantly decreased by the addition of EGMA, and the POE particle size and distribution decreased with the increase of the compatibilizer content up to 2% EGMA, beyond which the POE particle size and distribution remained unchanged. The reactions between the epoxy groups of EGMA and carboxylic or hydroxyl groups of PLA were elucidated by the Fourier transform infrared spectroscopy. Rheological results showed that the G′(ω), G″(ω), and complex viscosity of PLA/POE blends significantly increased at low frequencies with the addition of EGMA. The failure mode changed from brittle fracture of the neat PLA to ductile fracture of the PLA/POE blends.     

Zinc Dimethacrylate-Reinforced Thermoplastic Vulcanizates Based on Chlorinated Polyethylene Rubber/Ethylene-Vinyl Acetate Copolymer

A chlorinated polyethylene rubber (CPE)/ethylene-vinyl acetate copolymer (EVA) (weight ratio = 70/30) thermoplastic vulcanizate (TPV) was prepared by dynamic vulcanization, with the TPV being reinforced by various amounts of zinc dimethacrylate (ZDMA). The effects of ZDMA content on the mechanical and morphological properties of the TPVs were investigated. Experimental results indicated that dynamically vulcanized CPE/EVA blends without ZDMA showed an elastomeric behavior when the CPE/EVA weight ratio ranged from 90/10 to 50/50. The mechanical properties of dynamically vulcanized CPE/EVA blends were enhanced remarkably by the incorporation of ZDMA, especially when the ZDMA content was 5 phr. The fracture surface morphology of the reinforced CPE/EVA TPVs was relatively rough and drawn fibers could be found clearly. There were many ZDMA particles dispersed on the etched surface of the reinforced CPE/EVA TPVs with diameters of below about 10 μm. Energy dispersive X-ray spectrometer (EDS) results showed that the ZDMA particles were coated with CPE, the ZDMA particles being surrounded by a large number of small crosslinked CPE particles with diameters of 1 μm.     

Mechanical,Water-swelling,and Morphological Properties of Water-swellable Thermoplastic Vulcanizates Based on Polyvinyl Chloride/Crosslinked Sodium Polyacrylate/Chlorinated Polyethylene Blends

A novel water-swellable rubber (WSR) was prepared by dynamically vulcanizing polyvinyl chloride (PVC)/chlorinated polyethylene (CPE) blends where a crosslinked poly(sodium acrylate) (CPNaAA) was used as a super water-absorbent resin and dispersed in the CPE rubber. The mechanical, water-swelling, and morphological properties were investigated. The results showed that the dynamically vulcanized PVC/CPNaAA/CPE blends exhibited obvious elastomeric behavior and could be considered as thermoplastic vulcanizates (TPVs). The PVC/CPNaAA/CPE TPVs showed strong water-swelling ability, with the water-swelling ratio of the PVC/CPNaAA/CPE TPV with 30/60/70 weight ratio reaching 2400% at 200 h immersion. Moreover, compared with the first water-swelling behavior, the second and third water-swelling behaviors of the TPVs showed significantly improved water-swelling ratio and a remarkable decrease of weight loss. Morphological study showed that the interface interaction between the CPNaAA and CPE was weak. The CPNaAA particles in the blends could be separated and even be pulled out from the matrix under tensile stress, leading to the formation of suspended CPNaAA particles on the fracture surface of PVC/CPNaAA/CPE TPVs. The surface of the dried TPVs was rough and significant cavities could be found. The dynamic mechanical properties were investigated and the TPVs showed the typical Payne effect.     

Investigation of the Morphological and Mechanical Properties of Polyethylene Terephthalate (PET)/Ethylene Propylene Diene Rubber (EPDM) Blends in the Presence of Multi-Walled Carbon Nanotubes

In this study the blends of polyethylene terephthalate (PET)/ethylene propylene diene rubber (EPDM) in the presence of multi-walled carbon nanotubes (MWCNT) (1 and 3?wt %) were prepared by melt compounding in an internal mixer. Mechanical and morphological properties of the nanocomposites were investigated. The thermal behaviors of the PET/EPDM nanocomposites were also investigated, by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The results of the mechanical tests showed that the tensile strength, elastic modulus and the hardness of the blends were increased with increasing CNT, while the impact strength and elongation at break decreased. The DSC and TGA results showed an increase of melting temperature (T_m) and degradation temperature of the nanocomposites with the addition of the carbon nanotubes, because the carbon nanotubes serve both as nucleating agents to increase T_m and prevent the composite from degradation to increase the thermal stability. The microstructure of the composites was evaluated through field emission scanning electron microscopy (FESEM) and the results showed a good distribution of the MWCNT within the polymer blend.     

Dynamic Mechanical Properties of Phenolic Resin/Chlorinated Butyl Rubber Composites

Chlorinated butyl rubber composites were prepared by a compounding and vulcanizing process using phenolic resin (PF) as the vulcanizing agent and carbon black as filler. Instead of using the conventional vulcameter method to determine the vulcanizing parameters, the vulcanization temperature and time were obtained by differential scanning calorimetry (DSC) and tensile testing, respectively. Dynamic mechanical analysis (DMA) showed that, higher PF content resulted in higher E′ and lower tanδ, and variations of E′ and tanδ with temperature were consistent with the time-temperature equivalence principle. It is proposed that chlorinated butyl rubber using phenolic resin as the vulcanizing agent could be used as potential damping materials in the temperature range 20–100°C and frequencies 0.1–100 Hz.     

Thermoplastic Elastomers Based on Ethylene-vinyl Acetate Copolymer and Waste Nitrile Butadiene Rubber Powder Blends Compatibilized by Chlorinated Polyethylene

Thermoplastic elastomers (TPEs) based on ethylene-vinyl acetate (EVA)/waste nitrile butadiene rubber powder (WNBRP) blends compatibilized by chlorinated polyethylene (CPE) were prepared by melt-compounding. The tensile strength and the elongation at break of the EVA/CPE/WNBRP blends were increased significantly compared with those of the EVA/WNBRP blends. The fracture surfaces of the EVA/CPE/WNBRP blends were smooth; moreover, the WNBRP in the etched EVA/CPE/WNBRP blends were inserted in the EVA matrix tightly. DMA results revealed that when the CPE dosage was 5 phr in the EVA/CPE/WNBRP blend, the Payne effect was weakened significantly.     

Preparation,Morphology and Properties of Poly(Trimethylene Terephthalate)/Thermoplastic Polyester Elastomer Blends

Poly(trimethylene terephthalate)(PTT)/thermoplastic polyester elastomer (TPEE) blends were prepared and their miscibility, crystallization and melting behaviors, phase morphology, dynamic mechanical behavior, rheology behavior, spherulites morphology, and mechanical properties were investigated by differential scanning calorimetry (DSC), scanning electron microscopy (SEM), dynamic mechanical analysis (DMA), parallel-plate rotational rheometry, polarized optical microscopy (POM), wide angle X-ray diffraction (WAXD), universal tensile tester and impact tester, respectively. The results suggested that PTT and TPEE were partially miscible in the amorphous state, the TPEE rich phase was dispersed uniformly in the solid matrix with a size smaller than 2 μm, and the glass transition temperatures of the blends decreased with increasing TPEE content. The TPEE component had a good effect on toughening the PTT without depressing the tensile strength. The blends had improved melt viscosities for processing. When the blends crystallized from the melt state, the onset crystallization temperature decreased, but they had a faster crystallization rate at low temperatures. All the blends’ melts exhibited a predominantly viscous behavior rather than an elastic behavior, but the melt elasticity increased with increasing TPEE content. When the blends crystallized from the melt, the PTT component could form spherulites but their morphology was imperfect with a small size. The blends had larger storage moduli at low temperatures than that of pure PTT.     

Phase Morphology and Mechanical Properties of Polyamide-6/Polyolefin Elastomer-g-Maleic Anhydride Blends

The effects of addition of varying amounts of polyolefin elastomers (POE) (with and/or without grafted maleic anhydride) on the morphology and mechanical properties of polyamide-6 (PA6)-based blends were studied. Scanning electron microscopy (SEM) was employed to obtain some detailed quantitative analyses of the morphology of the fracture behavior for the blends containing 80 wt% PA6 and 20 wt% total elastomer. Impact strength, tensile strength, and flexural strength were also measured for these blends. The results showed that POE and PA6 were an incompatible system, but the POE-g-MAH was compatible and had a toughening effect on PA6. PA6-g-POE was formed through the reaction between POE-g-MAH and PA6 during the melt extrusion process, which reduced the size of the dispersed phase and improved the impact and tensile strength of the blends. The impact strength was improved by nine times compared with the pure PA6 or the binary blend PA6/POE when the blend ratio of the ternary blend PA6/POE/POE-g-MAH was 80/16/4.     

Study of Metallocene-Catalyzed Linear Low-Density Polyethylene Solid-State Extrusion: Processing and Mechanical Properties

The effect of extrusion temperature and extrusion drawing ratio (EDR) on the die swell ratio (DSR) and mechanical properties of metallocene-catalyzed linear low-density polyethylene (m-LLDPE) was examined with the application of solid-state extrusion (SSE). Scanning electron microscopy (SEM) was employed to characterize the microstructure and morphology of the extrudates. Extruded from a convergence-divergence die, compared with samples obtained by melt-state extrusion (MSE), the DSR decreases for SSE samples prepared at low extrusion temperature and high EDR. Mechanically strong SSE samples were also obtained at low extrusion temperatures and high EDR. Mechanically strong SSE samples were also obtained at low extrusion temperatures and high EDR. SEM indicates that the microstructures of the MSE samples consist primarily of ring-banded spherulites; the microstructure of the SSE samples was microfibers oriented along the direction of extrusion. The highly oriented microfibers contribute to the improved mechanical strength of the SSE samples.     

Effect of Silanes on Mechanical and Thermal Properties of Silicone Rubber/EPDM Blends

The effect of four types of silane coupling agents on the mechanical and thermal properties of silicone rubber and ethylene–propylene–diene monomer (M-class) rubber (EPDM) blends is studied, namely, isobutyltriethoxysilane (BUS), acryloxypropyltriethoxysilane (ACS), aminopropyltriethoxysilane (AMS), and vinyltriethoxysilane (VIS). ACS and VIS increase the crosslink density of the blends, which results in higher tensile strength, modulus, and thermal stability, but lower elongation at break compared with the other silanes. However, the blend containing BUS shows highest tanδ in the temperature range of 45°C to 200°C. Thermogravimetric analysis shows two steps of degradation for all the samples, but little difference with the varied silanes.     

Morphology and Mechanical Properties of Polyamide 6/Acrylonitrile-Butadiene-Styrene Blends Containing Carbon Nanotubes

The blends of polyamide 6/acrylonitrile-butadiene-styrene (PA6/ABS), with added styrene-maleic acid copolymer (SMA) compatibilizer, were prepared through melt mixing in an internal mixer. The effects of blend composition and various process conditions, as well as the addition of multi-wall carbon nanotubes (MWCNTs) to the blends, on the morphology and mechanical properties were investigated. The morphology of the blends and blend nanocomposites were observed by scanning electron microscopy (SEM) and analyzed using an image analysis technique. The mechanical behavior of the blends was investigated by tensile and also impact testing. The results showed that the blend composition as well as the processing conditions significantly affected the morphology and mechanical properties of the PA6/ABS blends. Among the various compositions, the blend with 36?wt.% of ABS and 4?wt.% of SMA compatibilizer exhibited the best mechanical properties. Comparing various speeds and times of mixing, it was found that less mixing speed and longer mixing times resulted in the favorable morphology and conditions for achievement of the desired toughness for the polyamide 6. By adding different amounts of MWCNTs to the blends, it was found that the presence of the carbon nanotubes changed the viscosity of the resulting nanocomposite and thus changed the morphology. These nanocomposites also showed an improvement in mechanical properties. The MWCNTs acted as a second compatibilizer, resulting in a synergistic effect on the mechanical properties of the PA6/ABS blend nanocomposites.     

Mechanical,Thermal, and Surface Properties of Ultrahigh Molecular Weight Polyethylene/Polypropylene Blends

Various compositions of ultrahigh molecular weight polyethylene/polypropylene (UHMWPE/PP) blends were prepared in decalin, with the rheological, mechanical, thermal, and surface properties of the blends being determined using the solution cast film. Viscosity and mechanical properties of the blends decreased below the additivity value with increasing PP content implying that PP molecules disturb the entanglement of UHMWPE. Contact angle of the blend films with a water drop increased with increasing content of PP. The atomic force microscope (AFM) images showed that the surface of cast UHMWPE was very smooth whereas that of cast PP was very uneven. For blends, the surface became rough and uneven with increasing content of PP. The melting temperature of PP (T _mP) decreased in the blends with increasing UHMWPE content while that of UHMWPE (T _mU) remained almost constant in blends.     

The Effect of Poly(Ethylene Succinate) on Mechanical Properties of PLLA/PES Blend Prepared by Melt-Blending

Fully biodegradable poly(L-lactide) and poly(ethylene succinate) (PLLA/PES) blends were prepared via melt-blending using PLLA and PES as reactants in a stainless steel chamber. The prepared PLLA/PES blend, as well as neat PLLA and PES, was characterized by Fourier transform infrared spectra (FTIR) and X-ray diffraction (XRD) to confirm the structure and the crystallization of PLLA in the blend. The mechanical properties of PLLA/PES blends were determined by bending and tensile tests and the effects of PES content on the mechanical properties of PLLA/PES blends were investigated. It was found that blending some amount of PES could significantly improve the elongation at break while still keeping considerably high strength and modulus. With increasing PES content, both strength and modulus gradually decreased; however the elongation at break significantly increased. SEM was used to examine the morphology of fracture surfaces of PLLA/PES blends.     

Mechanical Properties and Crystallization Behavior of Polycarbonate/Polypropylene Blends

The mechanical properties, morphology, and crystallization behavior of polycarbonate (PC)/polypropylene (PP) blends, with and without compatibilizer, were studied by tensile and impact tests, scanning electron microscopy (SEM), X-ray diffraction (XRD), and differential scanning calorimetry (DSC). The tensile and impact strengths of PC/PP blends decreased with increasing the PP content due to poor compatibility between the two phases. But the addition of compatibilizer improved the mechanical properties of the PC/PP blends, and the maximum value of the mechanical properties, such as tensile and impact strengths of PC/PP (80/20 wt%) blends, were obtained when the compatibilizer was used at the amount of 4 phr. The SEM indicated that the compatibility and interfacial adhesion between PC and PP phases were enhanced. DSC results that showed the crystallization and melting peak temperatures of PP increased with the increase of the PP content, which indicated that the amorphous PC affected the crystallization behavior. However, both the PC and compatibilizer had little effect on the crystallinity of PP in PC/PP blends based on both the DSC and XRD patterns.     

Morphological,Thermal and Mechanical Properties of Compatibilized Nylon 6/ABS Blends

Super‐tough nylon 6/ABS blends were prepared by using styrene/acrylonitrile/maleic anhydride co‐polymer (SAM) as a compatibilizer. The variations in morphology, mechanical behavior, and crystallinity associated with the reaction of the SAM with the nylon were characterized. The results showed that the addition of SAM to nylon 6/ABS blends enhanced the interfacial adhesion between nylon 6 and ABS, and this led to the decrease of ABS domain size and the improvement of mechanical properties of their blends. Moreover, it could be found that the crystallinity and phase morphology changed with the variation of SAM.     

Effect of Silica and Silicone Oil on the Mechanical and Thermal Properties of Silicone Rubber

The effect of three types of silicas with varied loading and the loading of hydroxyl terminated silicone oil on the mechanical and thermal properties of silicone rubbers (SRs) were investigated. Mechanical properties were affected by the silica loading because of the interaction between fillers and polymer and the filler dispersion. Fumed silica filled SRs showed higher tanδ, tensile strength, and elongation at break compared to those containing two types of precipitated silicas. With increasing silicone oil loading, the tensile strength, tear strength, hardness, and tanδ of SRs first increased and then decreased.     

Physical and Thermal Properties of High-Density Polyethylene Film Modified with Polypropylene and Linear Low-Density Polyethylene

Abstract

In view of the toughness and processing difficulty of high-density polyethylene (HDPE) film, the HDPE was modified by polypropylene (PP) and linear low density polyethylene (LLDPE), and the melt index, haze, dart impact strength, elongation at break were characterized. In addition the infrared spectra (IR), scanning electron microscopy (SEM), infrared image analysis, and differential scanning calorimetry (DSC) data were obtained. The results showed that the toughening effect of the 10%PP/30%LLDPE/60%HDPE composition was the best; the haze was reduced 6% and its dart impact strength and elongation at break were increased by 27.3% and 47%, respectively, relative to the pure HDPE. The blend of 10%PP/30%LLDPE/60%HDPE had compatibility. The melting point of the 10%PP/30%LLDPE/60%HDPE blend film increased by 5?°C compared with the pure HDPE film, with the results indicating the application fields of HDPE film could be widened.     

Mechanical Properties,Rheology, and Crystallization of Epoxy-Resin-Compatibilized Polyamide 6/Polycarbonate Blends: Effect of Mixing Sequences

Blends of polyamide 6 (PA6)/polycarbonate (PC)/epoxy resin (EP) were melt blended with three different mixing sequences. Their mechanical properties, crystallization, and rheological behaviors, as well as the morphology, were investigated via mechanical testing, differential scanning calorimetry (DSC), dynamic rheometry, and scanning electron microscopy (SEM). It was noted that the mixing sequences affected the distribution of EP in the PA6 matrix, as well as the reactivity of EP with PA6 and PC. Mechanical testing showed that the blends prepared by the first (S₁, blending PA6, PC, and EP simultaneously) and second mixing sequences (S₂, blending PC with a premixture of PA6/EP) had higher notched Izod impact strengths due to the formation of PA6-EP-PC block copolymer (named as the AEC structure) during compounding, as evidenced by the results of dynamic rheology and SEM. Whereas for the third sequence (S₃, blending PA6 with a premixture of PC/EP), EP could barely react with PA6 and PC, leading to little formation of AEC structure, which resulted in a poor notched Izod impact strength of the blends. The incorporation of EP actually acted as a plasticizer to improve the elongation at break of the S₃ blends. In addition, the DSC results and SEM observations showed that there were distinct differences in the crystallization and morphology of the samples prepared by the different mixing sequences.     

Influence of Reactive Compatibilizer on the Morphology,Rheological, and Mechanical Properties of Recycled Poly(Ethylene Terephthalate)/Polyamide 6 Blends

Recycled poly(ethylene terephthalate) (R-PET) and virgin polyamide 6 (PA6) blends compatibilized with glycidyl methacrylate grafted poly(ethylene-octene) (POE-g-GMA) were melt blended. The morphological, rheological and mechanical properties of the prepared blends were investigated by scanning electron microscopy, rheology, and an electromechanical testing instrument, respectively. All of the blends showed a droplet dispersion type morphology, and the PA6 particle size decreased with increase in the POE-g-GMA concentration. The storage modulus (G′), loss modulus (G′′), and complex viscosity (η*) of the blends significantly increased at low frequency with the addition of POE-g-GMA. In addition, ‘‘Cole-Cole’’ plots showed that the elasticity of the blends was also increased by raising the compatibilizer dosage. It was also found that 10 wt% of POE-g-GMA caused 88.46 and 171.05% increments in Charpy impact strength and elongation at break with only a 21.66% decrement in tensile strength.