Distribution by Scientific Domains

Terms modified by HDPE

  • hdpe matrix
  • hdpe resin

  • Selected Abstracts

    On the high-density polyethylene extrusion: Numerical, analytical and experimental modeling

    A. G. Mamalis
    Abstract A three-dimensional numerical model was developed to investigate the nonisothermal, non-Newtonian polymer flow through a cone cylindrical die used in the HDPE (high-density polyethylene) extrusion process. The numerical model was based on the computational fluid dynamics code COMSOL 3.4 the finite element method, and it was used to calculate pressure, flow, and temperature distributions in a cone cylindrical die used for industrial-scale extrusion of an HDPE rod. The model also accounted for viscous heating. In addition, pressure and temperature data were derived using an analytical solution. The numerical approach agrees fairly well with the experimental data recorded during the extrusion process of the material. © 2010 Wiley Periodicals, Inc. Adv Polym Techn 29:173,184, 2010; View this article online at wileyonlinelibrary. DOI 10.1002/adv.20185 [source]

    An experimental study of single-screw extrusion of HDPE,wood composites

    Karen Xiao
    Abstract Single-screw extrusion experiments were carried out to study the extrusion characteristics of HDPE,wood composites. Three screw geometries (A, B, and C) were used, and the effects of screw speed on output, melting, and pressure profile were studied. Screw A had a much higher compression ratio than screws B and C, which directly affected the melting behavior of the polymers. Screws B and C had the same compression ratio; however, screw C had the same metering capacity as screw A. Therefore, by comparing screws B and C, the effect of feed depth on the solid conveying capacity was investigated. It was found that while screw B had higher outputs than both screws A and C as expected, screw C had a much lower output than screw A for highly filled resins even though they had the same metering capacity. For HDPE, screws A and C showed the same output as expected. Further examinations of the pressure profiles and melting profiles from screw extraction experiments confirmed that screw C showed a severely starved solids conveying capacity for wood-filled resins, which limited the total outputs. Comparing the outputs and pressure generations between theoretical predictions and actual experimental results, it was evident that due to the inaccurate assumption of fully filled channels common in single screw extrusion, both outputs and pressure generations in the extruders were overpredicted. © 2010 Wiley Periodicals, Inc. Adv Polym Techn 29:197,218, 2010; View this article online at wileyonlinelibrary. DOI 10.1002/adv.20190 [source]

    Effect of EVA as compatibilizer on the mechanical properties, permeability characteristics, lamellae orientation, and long period of blown films of HDPE/clay nanocomposites

    Juliano Marini
    Abstract Two ethylene-vinyl acetate (EVA) resins with 19% (EVA19) and 28% (EVA28) of vinyl groups were used as compatibilizers for nanocomposites of high-density polyethylene (HDPE) and nanoclays. Two nanoclays were also used, one with a nonpolar surfactant (C15A) and another with a polar surfactant (C30B). The HDPE/EVA19/C15A formed an intercalated structure, while the HDPE/EVA28/C30B had surfactant loss. Blown films of these compositions were produced. A two-phase morphology made of HDPE and EVA/nanoclay particles was observed, which was responsible for the increase in water vapor and oxygen permeability rates of the films. The elastic modulus E along the transverse direction of the films was higher than along the machine direction due to preserved orientation given by the spiral die; the lamellae orientation was measured by small-angle X-rays diffraction. The highest E was observed in the HDPE/EVA19/C15A film due to stronger interactions. The long period of the HDPE lamellas was not affected by the presence of the EVA and nanoclay. A model was proposed to explain the improvement in elastic modulus due to the processing conditions and components' interactions. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source]

    Rheology behavior of high-density polyethylene/diluent blends and fabrication of hollow-fiber membranes via thermally induced phase separation

    Jianli Wang
    Abstract The phase-separation behavior of high-density polyethylene (HDPE)/diluent blends was monitored with a torque variation method (TVM). The torque variation of the molten blends was recorded with a rheometer. It was verified that TVM is an efficient way to detect the thermal phase behavior of a polymer,diluent system. Subsequently, polyethylene hollow-fiber membranes were fabricated from HDPE/dodecanol/soybean oil blends via thermally induced phase separation. Hollow-fiber membranes with a dense outer surface of spherulites were observed. Furthermore, the effects of the spinning temperature, air-gap distance, cold drawing, and HDPE content on the morphology and gas permeability of the resultant membranes were examined. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source]

    Crystallization and melting behavior of HDPE in HDPE/teak wood flour composites and their correlation with mechanical properties

    Kamini Sewda
    Abstract The nonisothermal crystallization behavior and melting characteristics of high-density polyethylene (HDPE) in HDPE/teak wood flour (TWF) composites have been studied by differential scanning calorimetry (DSC) and wide angle X-ray diffraction (WAXD) methods. Composite formulations of HDPE/TWF were prepared by varying the volume fraction (,f) of TWF (filler) from 0 to 0.32. Various crystallization parameters evaluated from the DSC exotherms were used to study the nonisothermal crystallization behavior. The melting temperature (Tm) and crystallization temperature (Tp) of the composites were slightly higher than those of the neat HDPE. The enthalpy of melting and crystallization (%) decrease with increase in the filler content. Because the nonpolar polymer HDPE and polar TWF are incompatible, to enhance the phase interaction maleic anhydride grafted HDPE (HDPE-g-MAH) was used as a coupling agent. A shift in the crystallization and melting peak temperatures toward the higher temperature side and broadening of the crystallization peak (increased crystallite size distribution) were observed whereas crystallinity of HDPE declines with increase in ,f in both DSC and WAXD. Linear correlations were obtained between crystallization parameters and tensile and impact strength. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source]

    Effect of the organoclay preparation on the extent of intercalation/exfoliation and barrier properties of polyethylene/PA6/montmorillonite nanocomposites

    Eleonora Erdmann
    Abstract Nanocomposites of HDPE matrix and 3 wt % organoclay/PA6 discontinuous phase were prepared in a mixer chamber. These nanocomposites of organoclay, PA6, and HDPE were characterized by X-ray diffraction, scanning electron and transmission electron microscopy (SEM and TEM). Barrier properties were determined by cyclohexane pervaporation and solubility. The results show that the degree of exfoliation and/or intercalation and the barrier properties depend on a combination of the proper chemical treatment and optimized processing in these polyethylene-organoclays nanocomposites. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source]

    Structure and properties of phase change materials based on HDPE, soft Fischer-Tropsch paraffin wax, and wood flour

    M. E. Mngomezulu
    Abstract Phase-change materials based on high density polyethylene (HDPE), soft Fischer-Tropsch paraffin wax (M3), and alkali-treated wood flour (WF) were investigated. The blend and composite samples were prepared by melt mixing using a Brabender Plastograph, followed by melt pressing. They were characterized in terms of their morphology, as well as thermal, mechanical, thermo-mechanical, and water absorption properties. Although SEM micrographs showed some evidence of intimate contact between the WF particles and the HDPE matrix as a result of alkali treatment, poor filler dispersion, and interfacial adhesion were also observed. Partial immiscibility of the HDPE and the M3 wax was noticed, with the WF particles covered by wax. There was plasticization of the HDPE matrix by the wax, as well as partial cocrystallization, inhomogeneity and uneven wax dispersion in the polymer matrix. The HDPE/WF/M3 wax composites were more homogeneous than the blends. The presence of wax reduced the thermal stability of the blends and composites. Both the presence of M3 wax and WF influenced the viscoelastic behavior of HDPE. The HDPE/M3 wax blends showed an increase in the interfacial amorphous content as the wax content increases, which resulted in the appearance of a ,-relaxation peak. The presence of M3 wax in HDPE reduced the mechanical properties of the blends. For the composites these properties varied with WF content. An increase in wax content resulted to a decrease in water uptake by the composites, probably because the wax covered the WF particles and penetrated the pores in these particles. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source]

    Photografting of acrylic acid and methacrylic acid onto polyolefines initiated by formaldehyde in aqueous solutions

    Jianmei Han
    Abstract Formaldehyde aqueous solution can act as an effective photoinitiating system for water-borne photografting. The photografting of acrylic acid (AA) and methacrylic acid (MAA) onto high-density polyethylene (HDPE), low-density polyethylene (LDPE) and polypropylene (PP) initiated by formaldehyde aqueous solutions has been reported. The effects of formaldehyde content and monomer concentration on grafting varied with the polymeric substrates and monomers used. For the grafting of AA onto HDPE, the extent of grafting increased with increasing formaldehyde content in the solution, monomer concentration had a little effect on grafting. Whereas for the grafting of MAA onto HDPE, the grafting performed in 8% formaldehyde aqueous solution lead to the highest extent of grafting, the extent of grafting increased with monomer concentration till 2.5 mol/L. MAA was easier to be grafted onto the polyolefins than AA. The easiness of grafting occurring on the polyolefins was in a decreasing order of LDPE > HDPE > PP. Qualitative and semi-quantitative Fourier transform infrared (FTIR) characterizations of the grafted samples were performed. For both grafted LDPE and PP samples, at the same irradiation time, the carbonyl index of the samples grafted with MAA was higher than that grafted with AA. The FTIR results are in accord with the results obtained by gravimetric method. The water absorbency of the grafted samples increased almost linearly with the extent of grafting. The PE films grafted with AA adsorbed more water than those grafted with MAA. This study had broadened the water-borne initiating system for photografting. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 [source]

    Influence of compatibilizer on notched impact strength and fractography of HDPE,organoclay composites

    Waraporn Rattanawijan
    Abstract The focus of this study was the notched impact property of high-density polyethylene (HDPE),organoclay composites and the resultant morphology of impact-fractured surfaces. Composites with a different organoclay content and degree of organoclay dispersion were compared with neat HDPE under identical conditions. The degree of organoclay dispersion was controlled through the use of a compatibilizer, maleic anhydride grafted polyethylene. It was found that the addition of organoclay can slightly increase the elastic modulus and notched impact strength of the composite. When the level of organoclay dispersion was improved by using compatibilizer, elastic modulus and toughness further increased. A significant increase in yield strength was also notable. The presence of organoclay was found to suppress strain hardening of the matrix during tensile testing. The impact-fractured surfaces of failed specimens were studied with scanning electron microscopy. The micromechanism for the increased toughness of HDPE,organoclay composites was discussed. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 [source]

    Simultaneous measurement of resistance and viscoelastic responses of carbon black-filled high-density polyethylene subjected to dynamic torsion

    Jianfeng Zhou
    Abstract The conduction and viscoelastic responses to temperature are measured simultaneously for carbon black (CB) filled high-density polyethylene (HDPE) subjected to dynamic torsion. PTC/NTC transition was correlated with the loss tangent peak and the quasi modulus plateau, which was ascribed to the filler network. The bond-bending model of elastic percolation networks was used to reveal the structural mechanisms for the cyclic resistance changes at different temperatures. The resistance changes at lower temperatures depended on the deformation of the polymer matrix, while the changes in melting state were mainly attributed to the rearrangement of the CB network. A simple scaling law is derived to relate resistance and dynamic storage modulus in the melting region. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source]

    Morphologies and mechanical properties of HDPE induced by small amount of high-molecular-weight polyolefin and shear stress produced by dynamic packing injection molding

    Zhanchun Chen
    Abstract To better understand the effect of a small amount of high-molecular-weight polyethylene (HMWPE) on the mechanical properties and crystal morphology under the shear stress field, the dynamic packing injection molding (DPIM) was used to prepare the oriented pure polyethylene and its blends with 4% HMWPE. The experiment substantiated that the further improvement of tensile strength along the flow direction (MD) of high-density polyethylene (HDPE)/HMWPE samples was achieved, whereas the tensile strength along the transverse direction (TD) still substantially exceeded that of conventional molding. Tensile strength in both flow and TDs were highly enhanced, with improvements from 23 to 76 MPa in MD and from 23 to 31 MPa in TD, besides the toughness was highly improved. So, the samples of HDPE/HMWPE transformed from high strength and brittleness to high strength and toughness. The obtained samples were characterized via SEM and TEM. For HDPE/HMWPE, the lamellae of the one shish-kebab in the oriented region may be stretched into other shish-kebab structures, and one lamella enjoys two shish or even more. This unique crystal morphology could lead to no yielding and necking phenomena in the stress,strain curves of HDPE/HMWPE samples by DPIM. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source]

    Toughening of recycled polystyrene used for TV backset

    Xiaoting Fu
    Abstract The recycled polystyrene (rPS) was toughened with ethylene-octylene copolymer thermoplastic elastomer (POE) and high-density polyethylene (HDPE) with various melt flow index (MFI), compatibilized by styrene-butadiene-styrene copolymer (SBS) to enhance the toughness of rPS for use as TV backset. The rPS/POE binary blends exhibited an increased impact strength with 5,10 wt % POE content followed by a decrease with the POE content up to 20 wt %, which could be due to poor compatibility between POE and rPS. For rPS/POE/SBS ternary blends with 20 wt % of POE content, the impact strength increased dramatically and a sharp brittle-ductile transition was observed as the SBS content was around 3,5 wt %. Rheological study indicated a possible formation of network structure by adding of SBS, which could be a new mechanism for rPS toughening. In rPS/POE/HDPE/SBS (70/20/5/5) quaternary blends, a fibril-like structure was observed as the molecular weight of HDPE was higher (with lower MFI). The presence of HDPE fibers in the blends could not enhance the network structure, but could stop the crack propagation during fracture process, resulting in a further increase of the toughness. The prepared quaternary blend showed an impact strength of 9.3 kJ/m2 and a tensile strength of 25 MPa, which can be well used for TV backset to substitute HIPS because this system is economical and environmental friendly. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source]

    Dynamic mechanical and thermal properties of PE-EPDM based jute fiber composites

    Gautam Sarkhel
    Abstract The present investigation deals with the mechanical, thermal and viscoelastic properties of ternary composites based on low density polyethylene (LDPE)-ethylene,propylene,diene terpolymer (EPDM) blend and high density polyethylene (HDPE)-EPDM blend reinforced with short jute fibers. For all the untreated and compatibilizer treated composites, the variation of mechanical and viscoelastic properties as a function of fiber loading (10, 20 and 30 wt %) and compatibilizer concentration (1, 2, and 3%) were evaluated. The flexural strength, flexural modulus, impact strength, and hardness increased with increasing both the fiber loading and the compatibilizer dose. The storage modulus (E,) and loss modulus (E,) of the HDPE-EPDM/jute fiber composites were recorded higher compared to those of the LDPE-EPDM/jute fiber composites at all level of fiber loading and compatibilizer doses. The tan, (damping efficiency) spectra showed a strong influence of the fiber loading and compatibilizer dose on the , relaxation process of polymer matrix in the composite. The thermo-oxidative stability was significantly enhanced for treated composites compared to untreated composites. Scanning electron microscopy investigation confirmed that the higher values of mechanical and viscoelastic properties of the treated composites compared to untreated composites is caused by improvement of fiber-matrix adhesion as result of compatibilizer treatment. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source]

    Amorphous orientation and its relationship to processing stages of blended polypropylene/polyethylene fibers

    Amy M. Trottier
    Abstract Changes in the molecular orientation, melting behavior, and percent crystallinity of the individual components in a fibrous blend of isotactic polypropylene (iPP) and high-density polyethylene (HDPE) that occur during the melt extrusion process were examined using wide-angle X-ray diffraction (WAXD) and differential scanning calorimetry (DSC). The crystalline orientation of each component was found using Wilchinsky's treatment of uniaxial orientation and described by the Hermans,Stein orientation parameter. The amorphous orientation was found by resolving the X-ray diffraction pattern in steps of the azimuthal angle into its iPP and HDPE crystalline and amorphous reflections. The utility of DSC and WAXD analyses to capture the effects of small differences in processing, and the use of these results as fingerprints of a particular manufacturing process were demonstrated. Major increases in the melting temperatures, percent crystallinities, and molecular orientations of the iPP and HDPE components occurred during the main stretching stage of the melt extrusion process. The annealing stage was found to have little to no effect on the melting behavior and molecular orientation of these components. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source]

    Direct fluorination of Twaron fiber and investigation of mechanical thermal and morphological properties of high density polyethylene and Twaron fiber composites

    J. Maity
    Abstract Composites consisting of high density polyethylene (HDPE) reinforced with randomly oriented chopped Twaron fibers (both fluorinated and nonfluorinated) show a significant increase in mechanical and thermal properties. To increase the better fiber matrix adhesion, the Twaron fiber is surface fluorinated using elemental fluorine. The surface of the Twaron fiber becomes very rough and the diameter of Twaron fiber increases from , 12 to 14 ,m after fluorination. The composites were prepared using solution method to overcome the damage of the fiber. The tensile strength and the Young's modulus increases with increasing fiber content. The tensile strength and modulus of modified fiber (fluorinated Twaron fiber) composites is much higher than nonmodified fiber composites indicating that there is better mechanical interlocking between the modified fiber and the matrix. Thermal properties obtained from DSC and DTA-TG analysis of the fluorinated fiber composites are also improved. Contact angle measurements, as well as the surface energy measurements, indicate that the composites are more wettable and is maximum for fluorinated fiber composites i.e., surface energy for fluorinated fiber composites is highest. Crystallinity is also higher for fluorinated fiber composites. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008 [source]

    Isothermal crystallization of high density polyethylene and nanoscale calcium carbonate composites

    Jiann-Wen HuangArticle first published online: 26 NOV 200
    Abstract High density polyethylene (HDPE) and calcium carbonate (CaCO3) nanocomposites with maleic anhydride grafted HDPE (manPE) as a compatibilizer were prepared via compounding in a twin-screw extruder. The CaCO3 are well dispersed in the HDPE matrix from the observation of transmission electron microscope. The isothermal crystallization kinetics was studied by differential scanning calorimetry and simulated by Avrami and Tobin models. The nucleation constants and fold surface free energy were estimated from Lauritzen,Hoffman relation. The results indicate that both manPE and well-dispersed CaCO3 particles would act as nuclei to induce heterogeneous nucleation and enhance crystallization rate. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source]

    Effect of morphology on the electric conductivity of binary polymer blends filled with carbon black

    Zhongbin Xu
    Abstract Several carbon black (CB)-filled binary polymer blends were prepared in Haake rheometer. Distribution states of CB and effect of morphology on the electric conductivity of different ternary composites were investigated. Under our experimental condition CB particles located preferentially at the interface between polymethyl methacrylate (PMMA) and polypropylene (PP) in PMMA/PP/CB composites, in high-density polyethylene (HDPE) phase in PP/HDPE/CB composites, and in Nylon6 (PA6) phase in polystyrene (PS)/PA6/CB, PP/PA6/CB, PMMA/PA6/CB, and polyacrylonitrile (PAN)/PA6/CB composites; the ternary composites in which CB particles locate at the interface of two polymer components have the highest electric conductivity when the mass ratio of the two polymers is near to 1 : 1. The ternary composites in which CB particles located preferentially in one polymer have the highest electric conductivity usually when the amount of the polymer component having CB particles is comparatively less than the amount of the polymer component not having CB particles; if the formulations of PS/PA6/CB, PP/PA6/CB, and PMMA/PA6/CB composites equaled and PA6/CB in them is in dispersed phase, PS/PA6/CB composites have the highest electric conductivity and PP/PA6/CB composites have the lowest electric conductivity; suitable amount of PS or PAN in PA6/CB composites increase the electric conductivity due in the formation of a parallel electrocircuit for electrons to transmit. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007 [source]

    Dispersion of graphite nanosheets in polymer resins via masterbatch technique

    Guohua Chen
    Abstract The dispersion of graphite nanosheets (GNs) in polymer matrices via the masterbatch technique was investigated. Modifying resin was added to GNs to prepare blend which is designated as the masterbatch. Such masterbatches, containing 70,80 wt % of GN filler, were blended with target polymers via melt extrusion process to prepare polymer/GN nanocomposites. The extruded nanocomposites showed characteristic conducting percolation behaviors with the percolation thresholds mainly dependent on the miscibility of the modifying resin with polymer matrix. The percolation thresholds of AS (Acrylonitrile-Styrene compolymer)/GN and high-density polyethylene (HDPE)/GN nanocomposites prepared by this technique were about 9 and 14 wt % of GN, respectively. Scanning electron microscopy and other characterizations showed that the GNs were well dispersed in AS and HDPE resins. The extrusion process and compatibility of the modifying resin with target polymer proved to be important factors for the homogeneity of the nanodispersion. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3470,3475, 2007 [source]

    Dynamic mechanical properties and morphology of high-density polyethylene/CaCO3 blends with and without an impact modifier

    Yu-Lin Yang
    Abstract Dynamic mechanical analysis and differential scanning calorimetry were used to investigate the relaxations and crystallization of high-density polyethylene (HDPE) reinforced with calcium carbonate (CaCO3) particles and an elastomer. Five series of blends were designed and manufactured, including one series of binary blends composed of HDPE and amino acid treated CaCO3 and four series of ternary blends composed of HDPE, treated or untreated CaCO3, and a polyolefin elastomer [poly(ethylene- co -octene) (POE)] grafted with maleic anhydride. The analysis of the tan , diagrams indicated that the ternary blends exhibited phase separation. The modulus increased significantly with the CaCO3 content, and the glass-transition temperature of POE was the leading parameter that controlled the mechanical properties of the ternary blends. The dynamic mechanical properties and crystallization of the blends were controlled by the synergistic effect of CaCO3 and maleic anhydride grafted POE, which was favored by the core,shell structure of the inclusions. The treatment of the CaCO3 filler had little influence on the mechanical properties and morphology. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3907,3914, 2007 [source]

    Thermal and mechanical properties of uncrosslinked and chemically crosslinked polyethylene/ethylene vinyl acetate copolymer blends

    H. A. Khonakdar
    Abstract Uncrosslinked and chemically crosslinked binary blends of low- and high-density polyethylene (PE), with ethylene vinyl acetate copolymer (EVA), were prepared by a melt-mixing process using 0,3 wt % tert -butyl cumyl peroxide (BCUP). The uncrosslinked blends revealed two distinct unchanged melting peaks corresponding to the individual components of the blends, but with a reduced overall degree of crystallinity. The crosslinking further reduced crystallinity, but enhanced compatibility between EVA and polyethylene, with LDPE being more compatible than HDPE. Blended with 20 wt % EVA, the EVA melting peak was almost disappeared after the addition of BCUP, and only the corresponding PE melting point was observed at a lowered temperature. But blended with 40% EVA, two peaks still existed with a slight shift toward lower temperatures. Changes of mechanical properties with blending ratio, crosslinking, and temperature had been dominated by the extent of crystallinity, crosslinking degree, and morphology of the blend. A good correlation was observed between elongation-at-break and morphological properties. The blends with higher level of compatibility showed less deviation from the additive rule of mixtures. The deviation became more pronounced for HDPE/EVA blends in the phase inversion region, while an opposite trend was observed for LDPE/EVA blends with co-continuous morphology. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3261,3270, 2007 [source]

    Blends of high density polyethylene and ethylene/1-octene copolymers: Structure and properties,

    Rameshwar Adhikari
    Abstract The morphology formation in the blends comprising a high density polyethylene (HDPE) and selected ethylene/1-octene copolymers (EOCs) was studied with variation of blend compositions using atomic force microscopy (AFM). The binary HDPE/EOC blends studied showed well phase-separated structures (macrophase separation) in consistence with individual melting and crystallization behavior of the blend components. For the blends comprising low 1-octene content copolymers, the lamellar stacks of one of the phases were found to exist side by side with that of the another phase giving rise to leaflet vein-like appearance. The formation of large HDPE lamellae particularly longer than in the pure state has been explained by considering the different melting points of the blend components. The study of strain induced structural changes in an HDPE/EOC blend revealed that at large strains, the extensive stretching of the soft EOC phase is accompanied by buckling of HDPE lamellar stack along the strain axis and subsequent microfibrils formation. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1887,1893, 2007 [source]

    A novel bisphosphonate inhibits inflammatory bone resorption in a rat osteolysis model with continuous infusion of polyethylene particles

    Miho Iwase
    Abstract This study examined the inhibitory effect of a new bisphosphonate (TRK-530) on wear debris-mediated bone resorption in a rat osteolysis model involving continuous infusion of high density polyethylene (HDPE) particles. TRK-530 (TRK) is a novel synthetic bisphosphonate that has been shown to decrease the level of tumor necrosis factor alpha (TNF-,) in the bone marrow of rats with adjuvant arthritis. Forty Wistar rats were randomized to two groups (n = 20 each). In each rat, a Kirshner (K) wire was inserted into the femur and HDPE particles were continuously infused into the knee joint. Thereafter, the animals were subcutaneously injected with saline (control group) or 1 mg/kg of TRK (TRK group) every second day, and were sacrificed at 4 or 8 weeks after surgery. Radiographs obtained at the time of sacrifice were evaluated for periprosthetic osteolysis. We also examined the thickness of the reactive membrane as well as the number of osteoclast-like cells around the K-wire. In addition, we examined the expression of genes for bone-resorbing cytokines in the reactive membrane. Radiographic peri-implant osteolysis was more frequent in the control group compared with the TRK group at each time of assessment (p < 0.01). The interfacial membrane was significantly thinner in the TRK group compared with the control group (p < 0.01) and the average number of osteoclast-like cells around the K-wire was significantly fewer in the TRK group (p < 0.01). In addition, the expression of interleukin 1-alpha messenger ribonucleic acid (IL-1, mRNA) and TNF-, mRNA was suppressed in the TRK group at each time of assessment. We conclude that the TRK can inhibit the formation of inflammatory peri-implant osteolysis induced by HDPE particles. © 2002 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved. [source]

    Direct characterization of phase behavior and compatibility in PET/HDPE polymer blends by confocal Raman mapping

    Shuangyan Huan
    Abstract Morphology, chemical distribution and domain size in poly(ethylene terephthalate)/high-density poly(ethylene) (PET/HDPE) polymer blends of various ratios prepared with and without maleic anhydride have been analyzed with confocal Raman mapping and SEM. The ratioimage method introduced here allows us to obtain enhanced chemical images with higher contrast and reliability. Compatibility numbers (Nc) are calculated to evaluate the compatibility of the blends. The incompatible polymer blends show heterogeneous distribution with phase separation behavior, while the semicompatible blends prepared with maleic anhydride show much smaller subphase distributions with less distinct interphases. After the blending modification by maleic anhydride of only 0.5%, the viscosity status and dispersibility between PET and HDPE could be substantially improved, and the interactions that exist between the two phases have also been proved by ATR-FT-IR results. High-spatial-resolution confocal Raman mapping coupled with the ratioimage method provides a very attractive way to characterize the compatibility and phase behavior of the polymer blend through different blending methodologies. Copyright © 2006 John Wiley & Sons, Ltd. [source]

    Low-Temperature Atomic Layer-Deposited TiO2 Films with Low Photoactivity

    Xinhua Liang
    Atomic layer deposition (ALD) has been successfully utilized for the conformal and uniform deposition of ultrathin titanium dioxide (TiO2) films on high-density polyethylene (HDPE) particles. The deposition was carried out by alternating reactions of titanium tetraisopropoxide and H2O2 (50 wt% in H2O) at 77°C in a fluidized bed reactor. X-ray photoelectron spectroscopy confirmed the deposition of TiO2 and scanning transmission electron microscopy showed the conformal TiO2 films deposited on polymer particle surfaces. The TiO2 ALD process yielded a growth rate of 0.15 nm/cycle at 77°C. The results of inductively coupled plasma atomic emission spectroscopy suggested that there was a nucleation period, which showed the reaction mechanism of TiO2 ALD on HDPE particles without chemical functional groups. TiO2 ALD films deposited at such a low temperature had an amorphous structure and showed a much weaker photoactivity intensity than common pigment-grade anatase TiO2 particles. [source]

    Effect of hindered piperidine light stabilizer molecular structure and UV absorber addition on the oxidation of HDPE.

    Part 2: Mechanistic aspects, electron spin resonance spectroscopy study, molecular modeling
    The first in this series of papers explored the effect of the structural characteristics of 2,2,6,6-tetramethylpiperidine-based hindered amine light stabilizers (HALS) on the thermal and photostabilization of high-density polyethylene. In the second part, the energies (stabilities) of the nitroxyl radicals and various intermediate species have been predicted using AccuModel® and related to stabilization performance and electron spin resonance (ESR) spectral data. Nitroxyl radicals with low predicted stability generally afforded improved thermal and photostabilization. ESR spectra were used to obtain values of nitroxyl radical concentration ([>NO·]) and g -factor as a function of pre-aging time for combinations of pre-aged HDPE and >NH HALS. Demethylation reactions of > N-methyl HALS resulted in uselessly weak ESR spectra. The HALS that afforded poor thermal oxidative stabilization gave rise to pronounced minima in [>NO·] that coincided with a maximum in hydroperoxide concentration. The g -factor values indicated that a predominant nitroxyl canonical form generally promoted superior thermal oxidative stabilization, whereas a predominance of the dipolar N·+O, form promoted superior photo-oxidative stabilization. These trends may be related to greater radical-scavenging and peroxide-trapping effects, respectively. Molecular modeling and ESR spectra can therefore provide valuable insight into the effectiveness of HALS and stabilization mechanisms. J. Vinyl Addit. Technol. 10:159,167, 2004. © 2004 Society of Plastics Engineers. [source]

    Effect of hindered piperidine light stabilizer molecular structure and UV-absorber addition on the oxidation of HDPE.

    Part 1: Long-term thermal, photo-oxidation studies
    This series of papers explores the effect of structural characteristics of 2,2,6,6-tetramethylpiperidine-based hindered amine light stabilizers (HALS) on the long-term (40 months) thermal (110°C in air) and photo-stabilization (Microscal unit wavelength >300 nm) performance characteristics of high-density polyethylene formulations. Possible synergism with a triazine functional UV absorber is also explored. Under thermal degradation (measured by carbonyl index) the polymeric HALS performed best, mainly because of reduced volatilization. Additionally, >N-methyl HALS generally showed superior performance under thermal degradation. There was no synergism between an N-CH3 polymeric HALS and the UV1164 triazine additive. However, the equivalent N-H polymeric HALS interacted in a complex manner with UV1164, giving synergism and antagonism, depending on HALS/UV1164 ratio. Strong synergism was evident with the monomeric HALS when the total stabilizer level was 0.2% w/w. Reduction in the overall stabilizer level to 0.05% w/w eliminated the synergism. The UV1164 alone led to rapid and intense yellowing; however, the rate and intensity of yellowing reduced dramatically upon combination with HALS, particularly when the UV1164 level was above 0.1% w/w. When the formulation was under UV attack, the molar mass and the type of N-substitution had no influence on stabilization performance because of the relatively low temperature of testing (leading to reduced volatilization), and the similarly effective UV-stabilization routes for N-methyl HALS and N-H HALS. Under UV attack, yellowing reached a maximum and then decreased to approximately the initial level, while HALS/UV1164 combinations generally showed weak antagonism. J. Vinyl Addit. Technol. 10:79,87, 2004. © 2004 Society of Plastics Engineers. [source]

    Additive interactions in the stabilization of film grade high-density polyethylene.

    Part I: Stabilization, influence of zinc stearate during melt processing
    The melt stabilization activity of some of the most commercially significant phenolic antioxidants and phosphites (alone and in combination), without and with zinc stearate, was studied in high-density polyethylene (HDPE) produced by Phillips catalyst technology. Multiple pass extrusion experiments were used to degrade the polymer melt progressively. The effect of stabilizers was assessed via melt flow rate (MFR) and yellowness index (YI) measurements conducted as a function of the number of passes. The level of the phenolic antioxidant remaining after each extrusion was determined by high-performance liquid chromatography (HPLC). Phenolic antioxidants and phosphites both improved the melt stability of the polymer in terms of elt viscosity retention; the influence of zinc stearate was found to be almost insignificant. However, phosphites and zinc stearate decreased the discoloration caused by the phenolic antioxidants. A correlation was found between the melt stabilization performance of phosphites and their hydroperoxide decomposition efficiency determind via a model hydroperoxide compound. Steric and electronic effects associated with the phosphorus atom influenced the reactivity towards hydroperoxides. Furthermore, high hydrolytic stability did not automatically result in lower efficiency. Besides phosphite molecular structure, stabilization activity was also influenced by the structure of the primary phenolic antioxidant and the presence of zinc stearate. [source]

    High-density polyethylene (HDPE)-degrading potential bacteria from marine ecosystem of Gulf of Mannar, India

    V. Balasubramanian
    Abstract Aims:, Assessment of high-density polyethylene (HDPE)-degrading bacteria isolated from plastic waste dumpsites of Gulf of Mannar. Methods and Results:, Rationally, 15 bacteria (GMB1-GMB15) were isolated by enrichment technique. GMB5 and GMB7 were selected for further studies based on their efficiency to degrade the HDPE and identified as Arthrobacter sp. and Pseudomonas sp., respectively. Assessed weight loss of HDPE after 30 days of incubation was nearly 12% for Arthrobacter sp. and 15% for Pseudomonas sp. The bacterial adhesion to hydrocarbon (BATH) assay showed that the cell surface hydrophobicity of Pseudomonas sp. was higher than Arthrobacter sp. Both fluorescein diacetate hydrolysis and protein content of the biofilm were used to test the viability and protein density of the biomass. Acute peak elevation was observed between 2 and 5 days of inoculation for both bacteria. Fourier transform infrared (FT-IR) spectrum showed that keto carbonyl bond index (KCBI), Ester carbonyl bond index (ECBI) and Vinyl bond index (VBI) were increased indicating changes in functional group(s) and/or side chain modification confirming the biodegradation. Conclusion:, The results pose us to suggest that both Pseudomonas sp. and Arthrobacter sp. were proven efficient to degrade HDPE, albeit the former was more efficacious, yet the ability of latter cannot be neglected. Significance and Impact of the Study:, Recent alarm on ecological threats to marine system is dumping plastic waste in the marine ecosystem and coastal arena by anthropogenic activity. In maintenance phase of the plastic-derived polyethylene waste, the microbial degradation plays a major role; the information accomplished in this work will be the initiating point for the degradation of polyethylene by indigenous bacterial population in the marine ecosystem and provides a novel eco-friendly solution in eco-management. [source]

    On Processing and Impact Deformation Behavior of High Density Polyethylene (HDPE),Calcium Carbonate Nanocomposites

    Qiang Yuan
    Abstract Different processing approaches were adopted to obtain the best combination of strength and toughness. The approach that yielded superior properties was examined in detail to study the mechanical response of nanoscale calcium carbonate-reinforced high density polyethylene in conjunction with unreinforced high density polyethylene. The reinforcement of high density polyethylene with nanoscale calcium carbonate increases impact strength and is not accompanied by decrease in yield strength. The addition of nanoscale calcium carbonate to high density polyethylene alters the micromechanism of deformation from crazing-tearing in high density polyethylene to fibrillation in high density polyethylene,calcium carbonate nanocomposite. [source]

    Study on the Phase Behavior of High Density Polyethylene , Ethylene Octene Copolymer Blends

    Daniela Mileva
    Abstract The processes of melting and crystallization of blends based on HDPE and EOC were investigated. DSC thermograms showed that a separate crystallization and co-crystallization occurred in the blends studied. Avrami approach was used to analyze the kinetics of crystallization in the blends. It is shown that the Avrami exponent depends on the EOC concentration of the samples studied. The difference in the Avrami parameters for HDPE, EOC and the blends indicated that the nucleation mechanism and dimension of the spherulite growth of the blends were different from that of HDPE to some extent. The crystal growth was examined in the context of the Lauritzen-Hoffman theory. DSC traces obtained at different cooling rates were used for analyzing the non-isothermal crystallization. It was found that the Ozawa model was rather inapplicable for the materials studied. In contrast, the Avrami equation modified by Jeziorny can be used more efficiently to describe the non-isothermal crystallization behavior of HDPE-EOC blends. [source]