Structure and properties of nylon 6 modified by γ-irradiated linear low density polyethylene

In this work, structure and properties of blends of nylon 6 with 10% linear low density polyethylene γ-irradiated in air at different integrated doses are presented. More particularly, Molau tests, DSC, SEM, and mechanical tests have been performed. Results show that positive morphological changes with respect to the blend with unirradiated linear low density polyethylene are well evident, especially in the blend with polyethylene irradiated at 50 KGy. This blend also shows an enhancement of the elongation at break and of the impact properties.     

EVA对农膜再生料的力学性能及流变性能的影响

用熔融共混法制备了EVA与农膜再生料（RPE）的共混材料,研究了EVA对农膜再生料的改性作用,并与新料低密度聚乙烯（LDPE）进行了对比研究。对再生料、改性材料和新料进行了力学性能分析、旋转流变分析、转矩流变分析和形貌分析。结果表明,EVA可以显著提高农膜再生料的断裂伸长率,对拉伸强度影响不大,当EVA用量为50%时,改性材料的断裂伸长率和拉伸强度都和新料相当。EVA可以提高再生料的相容性,改善其流变性能和加工性能,使再生料的流变行为接近新料,更容易加工。     

Effects of the γ-irradiation strength and basalt additive content on the mechanical performance and dielectric response of polypropylene films

In this study, we investigated the effects of high-dose γ-ray irradiation on the mechanical and dielectric properties of polypropylene (PP)–basalt thick films. PP–basalt thick-film composites with various basalt contents from 0.5 to 10.0% were prepared by a hot-press method. The samples were exposed to γ radiation at different doses in the range 3–25 kGy. The mechanical properties of the samples, such as the Young's modulus, tensile strength, percentage strain at break, and energy at break, were examined in the context of the γ-irradiation process. Although the maximum elasticity was obtained for the unirradiated 0.5% basalt-added composite, the 6 kGy γ-irradiated PP–1.0% basalt sample exhibited the highest elasticity properties among all of the composites. The best mechanical properties, including the ultimate tensile strength and energy at break values, were achieved for the 12 kGy γ-irradiated neat PP. The dielectric properties of the PP–basalt composites were also investigated in the 100 Hz to 15 MHz frequency region at room temperature. According to the analysis of the dielectric properties, the 3 kGy γ-irradiated neat PP may have potential for microelectronic device applications that require low dielectric constant and dielectric loss materials. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47414.     

Modification of polyester resins by an oligomeric additive

Blends of unsaturated polyester resin (UP) and polyethylene terephthalate oligomers (PETO) have been prepared with different relative compositions. These materials form a kind of semiinterpenetrating polymer networks (semi-IPN's) in which the microstructure and the tensile properties are shown to depend on composition. Impact strength of the blends is also reported, and the performance of the blends was found to be superior to pure UP.     

γ-Irradiation Effects on Opto-Thermal and -Mechanical Properties of PET and PETG Fibers

Changes in opto-thermal and -mechanical properties of polyethylene terephthalate and glycol-modified polyethylene terephthalate (4 wt% of ethylene glycol) subjected to γ-irradiation at doses up to 30 Mrad and a dose rate of 138.8 rad/sec, were investigated by interferometry. Empirical formulae are suggested to correlate the opto-thermal and -mechanical properties of the γ-irradiated fibers with the applied dose. Microinterferograms and relationships between the parameters obtained are given for illustration.     

Barrier properties of blends based on liquid crystalline polymers and polyethylene

Blends of an extrusion‐grade polyethylene and two different liquid crystalline polymers of Vectra type were prepared by melt mixing using poly(ethylene‐comethacrylic acid) as compatibilizer. Oxygen and water vapor permeability, transparency and welding strength of compression molded and film blown specimens were studied. The compression molded blends showed gas permeabilities conforming to the Maxwell equation assuming low permeability liquid crystalline polymer spheres in a high permeability polyethylene matrix. One of the liquid crystalline polymers with suitable rheological properties formed a more continuous phase in the film blown blends and a substantial decrease in oxygen and water vapor permeability was observed in these blends. The compression molded blends with 50% liquid crystalline polymer and some of blow molded blends showed very high gas permeabilities. It is believed that voids forming continuous paths through the structure were present in these samples. The blends showed significantly higher opacity than pure polyethylene.     

Ethylene polymerization with hybrid nickel diimine/Cp2TiCl2 catalyst: a new method to prepare blends of linear and branched polyethylene

Blends of linear polyethylene (LPE) and branched polyethylene (BPE) display very good mechanic properties that can be beneficial for various applications such as shear thinning and melt elasticity. LPE, BPE and amorphous polyethylene can be produced using nickel diimine (DMN) catalyst under various polymerization conditions, while LPE can be obtained using metallocene catalyst. Thus, LPE/BPE blends can be achieved by in situ polymerization using a hybrid DMN/metallocene catalyst. A novel hybrid catalyst made of DMN and Cp₂TiCl₂ was designed and used for ethylene polymerization. A synergistic effect of the two active sites in the hybrid DMN/metallocene catalyst was observed. Blends of linear and low branched polyethylene were synthesized when polymerization was conducted at low temperature (0 °C), while blends of linear and highly branched polyethylene were obtained at high temperature (50 °C). However, the miscibility of the polymers obtained at 50 °C was dramatically reduced as compared to those obtained at 0 °C. Mesoporous particles (MCM‐41) consisting of aluminosilicate with cylindrical pores were used to support the hybrid catalyst, in which MCM‐41 provides sufficient nanoscale pores to facilitate the polymerization in well‐controlled confined spaces. Blends of LPE and BPE were synthesized by in situ polymerization without adding comonomer and characterized. The miscibility of the polymer blends can be improved by supporting the hybrid catalyst on MCM‐41. Copyright © 2009 Society of Chemical Industry     

Effects of electron beam irradiation on the structure–property behavior of blends based on low density polyethylene and styrene-ethylene-butylene-styrene-block copolymers

Low density polyethylene (LDPE) blends with different additives were exposed to various doses of electron beam irradiation. The additives used were styrene-ethylene-butylene-styrene-block copolymers (SEBS), styrene-ethylene-butylene-styrene-block copolymer grafted with maleic anhydride (SEBS-g-MA) and mineral compounds. The structure–property behavior of electron beam irradiated blends was characterized in terms of mechanical, thermal, and electrical resistivity properties. The results indicated that the unirradiated LDPE blends with the different compositions showed improved mechanical properties, thermal and volume resistivity properties than pure LDPE. However, the improvement in properties of unirradiated blends by using SEBS-g-MA was higher than using SEBS copolymer. Further improvement in the mechanical, thermal and electrical properties of the LDPE blends was achieved after electron beam irradiation. The limited oxygen index (LOI) data revealed that the LDPE/SEBS-g-MA/ATH blend was changed from combustible to self-extinguishing material after electron beam irradiation to a dose of 100 kGy. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Mechanical properties of HDPE–PS–SEBS blends

Blends of high-density polyethylene (HDPE), polystyrene (PS), and an SEBS triblock copolymer were extruded, pelletized, and injection molded. The binary HDPE–PS blends exhibit very poor ductibility; however, addition of the SEBS block copolymer greatly improves this characteristic but with an accompanying loss in strength and modulus. The modified blends are very tough and have mechanical properties suitable for many end use applications. However, weld lines pose a problem and should be avoided with these blends.     

Processing properties of high- and low-density polyethylenes and their blends

Blends of two characterized linear polyethylenes with a branched polyethylene have been prepared by melt extrusion. It has been found that the linear polyethylenes can be shear modified in a reversible manner similar to branched polymers and that this shear modification and its reversal by re-heating does not change the molecular weight distribution, thereby indicating that the shear modification is a physical rather than chemical change in structure. Because both the high- and low-density polyethylene components of the blends are capable of undergoing reversible shear modification, it is possible to produce blends with either greater or less melt elasticity than the individual components by adjusting the conditions of blending. This demonstrates that the correlation of the properties of blends with the properties of their components should not be attempted without consideration of the effect of the blending process on the properties of the individual components.     

Use of postconsumer polyethylene in blends with polyamide 6: Effects of the extrusion method and the compatibilizer

Blends of polyamide and high‐density polyethylene show adequate properties for a large range of applications: they are used for the production of filaments, containers, and molding resins. The effect of the addition of 2 wt % of a compatibilizer, maleic anhydride grafted polyethylene, to the blend was studied and compared to the use of postconsumer polyethylene. The samples were extruded with single‐ and twin‐screw extruders with 25, 50, or 75 wt % f polyethylene, and the test specimens, molded by injection, were characterized by stress–strain tests, thermal properties, and morphologies. Processing the blends with postconsumer polyethylene in both extruders improved the mechanical properties in comparison to the blends processed with high‐density polyethylene and the compatibilizer. The morphologies of these blends showed that there was a decrease in the domain size of the disperse phase with the use of the compatibilizer or postconsumer polyethylene. The results indicate that for this blend, postconsumer polyethylene substituted, with advantages, for the necessity of a compatibilizer and the use of the high‐density polyethylene. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008.     

Morphology and mechanical properties of blends of linear low density polyethylene and poly(ethene‐propene‐1‐butene)

Blends of linear low density polyethylene (LLDPE) and ethene‐propene‐1‐butene copolymer (t‐PP) were obtained through mechanical mixing using a single‐screw extruder with different compositions: 20, 40, 50, 60, and 80 wt % of t‐PP. For this, two types of polyethylene were used: 1‐hexene comonomer and 1‐octene comonomer based. The same blends were prepared in a batch mixer and the torque and temperature were analyzed. The torque showed a decrease with increasing t‐PP content, indicating better processability of the mixture in comparison with LLDPE. The morphology of the blends was analyzed by SEM and showed a composition dependence. The mechanical properties of the blends were evaluated by tensile tests. The results revealed that the best properties were obtained in a 20% t‐PP blend. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1255–1261, 2006     

Morphology of polyethylene blends. II: Formation of a range of morphologies in blends of polyethylene with increasing content of styrene-isoprene-styrene triblock copolymers during extrusion-blowing

Blends containing polyethylene (LDPE, LLDPE, or LDPE-LLDPE) with different weight percent of styrene-isoprene-styrene (SIS) triblock copolymers have been obtained by extrusion-blowing. The morphology of the blends, investigated by scanning electron microcopy (SEM), has been related to composition but also to different parameters such as viscosity, nature of the polyethylene phase, and extrusion conditions. A large range of morphologies is observed and indicates that the main factors determining the morphology of the blends are the composition, the elongational fields at the exit of the die and, in certain limits, the relative viscosities of the components of the blends.     

Graft copolymer modification of polyethylene–polystyrene blends. II. Properties of modified blends

The use of graft copolymers of styrene onto polyethylene as additives to improve the mechanical properties of polyethylene–polystyrene blends is described. Blends containing equal proportions of low-density polyethylene and polystyrene were selected for this study since this composition represents the poorest balance of properties in this system. Graft addition generally increased both the yield strength and the elongation at break of the blend. Of the grafts employed, those prepared at an irradiation dose near 0.5 megarad appear optimal for this purpose. These conditions apparently balance the beneficial effects of grafting extent and the detrimental effects of crosslinking, both of which increase with irradiation dose.     

Model Free Approach for Non-Isothermal Decomposition of Un-Irradiated and γ-Irradiated Silver Acetate: New Route for Synthesis of Ag(2)O Nanoparticles

Kinetic studies for the non-isothermal decomposition of unirradiated and γ-irradiated silver acetate with 10(3) kGy total γ-ray doses were carried out in air. The results showed that the decomposition proceeds in one major step in the temperature range of (180-270 °C) with the formation of Ag(2)O as solid residue. The non-isothermal data for un-irradiated and γ-irradiated silver acetate were analyzed using Flynn-Wall-Ozawa (FWO) and nonlinear Vyazovkin (VYZ) iso-conversional methods. These free models on the investigated data showed a systematic dependence of Ea on α indicating a simple decomposition process. No significant changes in the thermal decomposition behavior of silver acetate were recorded as a result of γ-irradiation. Calcinations of γ-irradiated silver acetate (CH(3)COOAg) at 200 °C for 2 hours only led to the formation of pure Ag(2)O mono-dispersed nanoparticles. X-ray diffraction, FTIR and SEM techniques were employed for characterization of the synthesized nanoparticles.     

Blends of polyamide 6 with low‐density polyethylene compatibilized with ethylene–methacrylic acid based copolymer ionomers: Effect of neutralizing cations

Blends of polyamide 6 with low‐density polyethylene compatibilized with sodium‐, zinc‐, and lithium‐neutralized ethylene—methacrylic acid ionomers were investigated at 11, 33, and 55 wt % neutralization of the ionomers. Blends of polyamide 6 with low‐density polyethylene without a compatibilizer had poor properties characteristic of incompatible polymer–polymer blends. After the addition of a compatibilizer, tensile properties improved, the modulus drop associated with melting increased to higher temperatures, and the dispersed phase size decreased. The improvement of the mechanical properties and thermomechanical properties was less with the acid copolymer than with the ionomers. Overall, ionomers neutralized with sodium, zinc, or lithium showed little difference in their compatibilization efficiency. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Preparation of HDPE/UHMWPE/MMWPE blends by two-step processing way and properties of blown films

Summary Blends of high density polyethylene (HDPE) and ultra high molecular weight polyethylene (UHMWPE) were prepared by two-step processing way. Middle molecular weight polyethylene (MMWPE) as a fluidity modifier and compatilizer was added into UHMWPE in the first step, and then modified UHMWPE and HDPE were blending extruded to prepare the HDPE/UHMWPE/MMWPE blends used for blown films. The mechanical test of the blown films revealed that when the content of MMWPE in modified UHMWPE was 40wt% and the content of UHMWPE in the blends was 20 wt%, the film had the optimal mechanical properties. The tensile strength and tear strength of the film increased by 50% and 21%, respectively, compared with those of pure HDPE film. Rheological curves indicated that the melt torque and the apparent viscosity of the HDPE/UHMWPE/MMWPE blends made by two-step processing way both greatly reduced than other blends. The results from DSC suggested that the blends by two-step processing way may form more stable and perfect co-crystallization. PLM (polarized light microscopy) and SEM micrographs revealed that two-step processing way can improve the surface morphology of the films and make the dispersion of UHMWPE particles in HDPE increase.     

Influence of thermal and morphological characteristics on mechanical responses of polypropylene/γ‐irradiated elastomer blends

The approach of this paper is to examine the mechanical responses of polypropylene (PP)/γ‐irradiated ethylene acrylic elastomer blends and subsequently compare them with the PP/unirradiated ethylene acrylic elastomer blends. Thorough correlations were drawn between the mechanical characteristics of blends and their morphological, thermal, thermomechanical, and fractured surface morphological aspects. The idea of carrying out γ‐irradiation was to introduce crosslinking points in the elastomer phase. For better understanding, correlations between the impact test results and the fractured surface morphologies were analyzed. The limited tensile properties of PP/γ‐irradiated elastomer blends were attributed not only to the poor interfacial adhesion, obtained by fitting with several theoretical mechanical models, but also to the substantially higher elastomer particle size in the blends than in the PP/unirradiated elastomer blends. The higher loss modulus and tan δ values for PP/unirradiated elastomer blends along with the attainment of much smaller particles of elastomers were responsible for the phenomenal increase in impact properties, which was actually attributed to the formation of crazes inside the dispersed phase during applied impact stress. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46597.     

The effect of γ-irradiation on optical and electrical properties of polycarbonate

Poly-(bisphenol A carbonate) (PC) samples were exposed to different doses of γ-rays from a ⁶⁰Co source (from 0.05 to 0.3 M rad) at room temperature. Conductivity and dielectric constant as well as optical measurements were carried out. It was noticed that almost no work has been reported on the electrical conductivity of polycarbonate at high temperatures. γ-irradiation of polycarbonate is believed to create free radicals which increases the state of disorder and perturb the orientation of dipoles inside the polymer. At about 95°C, the electrical conductivities of irradiated samples were found to increase by nearly one order of magnitude with respect to the unirradiated one. The dielectric constant, ?, of fresh polycarbonate was nearly temperature independent over a range of ～ 70°C, then it increased with temperature, but for γ-irradiated samples (from 0.05 to 0.3 M rad) the dielectric constant increased continuously with temperature and also with respect to the fresh sample what confirms the effect of γ-irradiation in perturbing the orientation of the dipoles in the polymer. It was found that the UV absorption spectrum has a broad band at 0.280 μm and the absorption intensity was strongly dependent on the dose of γ-irradiation.