The Experts below are selected from a list of 51 Experts worldwide ranked by ideXlab platform

Loredana Incarnato - One of the best experts on this subject based on the ideXlab platform.

  • Three-layered coextruded cast films based on conventional and metallocene poly(ethylene/α-olefin) copolymers
    Journal of Plastic Film and Sheeting, 2013
    Co-Authors: Paola Scarfato, Emilia Garofalo, Luciano Di Maio, Loredana Incarnato
    Abstract:

    Multilayer films of a conventional linear low-density poly(ethylene/α-octene) (LLDPE) and a metallocene linear low-density poly(ethylene/α-hexene) (mLLDPE) copolymers were produced by cast co-extrusion process. Coextruded films were obtained by varying the position and the relative thicknesses of the two polymers. Mechanical (tensile and impact) tests, permeability, haze and hot tack measurements were carried out on the produced films in order to verify the effect of layer composition and position on the performances of the coextruded samples. Thermal and atomic force microscopy characterizations of the three-layer structures were also performed to correlate the resulting morphology with the film properties. The experiments demonstrated that, at fixed composition, the structures having the mLLDPE copolymer as external layers exhibit generally better mechanical performances and a widening in the Sealability Temperature window due to a lowering of 5℃ in the Seal-Initiation Temperature, with only a small inc...

Incarnato Loredana - One of the best experts on this subject based on the ideXlab platform.

  • Three-layered coextruded cast films based on conventional and metallocene poly(ethylene/α-olefin) copolymers
    'SAGE Publications', 2014
    Co-Authors: Scarfato Paola, Di Maio Luciano, Garofalo Emilia, Incarnato Loredana
    Abstract:

    Multilayer films of a conventional linear low-density poly(ethylene/α-octene) (LLDPE) and a metallocene linear low-density poly(ethylene/α-hexene) (mLLDPE) copolymers were produced by cast co-extrusion process. Coextruded films were obtained by varying the position and the relative thicknesses of the two polymers. Mechanical (tensile and impact) tests, permeability, haze and hot tack measurements were carried out on the produced films in order to verify the effect of layer composition and position on the performances of the coextruded samples. Thermal and atomic force microscopy characterizations of the three-layer structures were also performed to correlate the resulting morphology with the film properties. The experiments demonstrated that, at fixed composition, the structures having the mLLDPE copolymer as external layers exhibit generally better mechanical performances and a widening in the Sealability Temperature window due to a lowering of 5°C in the Seal-Initiation Temperature, with only a small increase (max 3.5%) in the film haze percentages. The oxygen permeability values do not seem to be significantly affected by the structure composition and layout

Hiroyuki Hamada - One of the best experts on this subject based on the ideXlab platform.

  • the effect of heat Sealing Temperature on the properties of opp cpp heat Seal i mechanical properties
    Journal of Applied Polymer Science, 2005
    Co-Authors: Tsujii Tetsuya, U S Ishiaku, Machiko Mizoguchi, Hiroyuki Hamada
    Abstract:

    The effect of heat Sealing Temperature on the mechanical properties and morphology of OPP/CPP laminate films was investigated. The laminated films were placed in an impulse type heat Sealing machine with both CPP sides facing each other. The Temperatures investigated ranged from 100 to 250°C. T-peel and tensile tests in combination with SEM were used to characterize the heat Seals. A minimum Seal Initiation Temperature of 120°C was identified for OPP/CPP laminate heat Sealing. Peel strength increased sharply from zero at 110°C to maximum at 120°C, after which a gradual decrease was observed. Tensile strength initially increased until 120°C, after which it gradually decreased until 170°C and assumed a constant value beyond that. The initial rise has been associated to cold crystallization, while the reduction between 120°C and 170°C was due to relaxation in molecular orientation. Beyond 170°C, all the orientation in the laminate has been lost so orientation effects are nullified. Morphological studies with SEM revealed that Seals were partially formed at lower Temperatures, while the laminates were totally fused together at high Temperatures, with intermediate Temperatures showing properties that lie in between. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 753–760, 2005

  • The effect of heat Sealing Temperature on the properties of OPP/CPP heat Seal. I. Mechanical properties
    Journal of Applied Polymer Science, 2005
    Co-Authors: Tsujii Tetsuya, U S Ishiaku, Machiko Mizoguchi, Hiroyuki Hamada
    Abstract:

    The effect of heat Sealing Temperature on the mechanical properties and morphology of OPP/CPP laminate films was investigated. The laminated films were placed in an impulse type heat Sealing machine with both CPP sides facing each other. The Temperatures investigated ranged from 100 to 250°C. T-peel and tensile tests in combination with SEM were used to characterize the heat Seals. A minimum Seal Initiation Temperature of 120°C was identified for OPP/CPP laminate heat Sealing. Peel strength increased sharply from zero at 110°C to maximum at 120°C, after which a gradual decrease was observed. Tensile strength initially increased until 120°C, after which it gradually decreased until 170°C and assumed a constant value beyond that. The initial rise has been associated to cold crystallization, while the reduction between 120°C and 170°C was due to relaxation in molecular orientation. Beyond 170°C, all the orientation in the laminate has been lost so orientation effects are nullified. Morphological studies with SEM revealed that Seals were partially formed at lower Temperatures, while the laminates were totally fused together at high Temperatures, with intermediate Temperatures showing properties that lie in between. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 753–760, 2005

Abdellah Ajji - One of the best experts on this subject based on the ideXlab platform.

  • Tailoring Heat-Seal Properties of Biodegradable Polymers through Melt Blending
    International Polymer Processing, 2017
    Co-Authors: Ramin Yousefzadeh Tabasi, Abdellah Ajji
    Abstract:

    Abstract In this study, we address heat-Seal properties of poly (lactic acid) (PLA), blended with Poly (butylene adipate-co-terephthalate) (PBAT). The objective is to correlate blends crystalline structure and morphology to corresponding heat-Seal of blends films. The SEM micrographs show a two-phase elongated morphology where stretched ellipsoids developed through elongational flow during the cast film process. To distinguish the effect of crystallization, we also prepared amorphous and crystalline PBAT films and then compared them to blends with PLA. Heat-Sealed areas were created by putting film surfaces in intimate contact for 1 s at the pressure of 0.5 N/mm2 or Pa and in the Temperature range of 70 to 140 °C. Thermal analysis shows that the crystalline structure of PBAT has a significant effect on shifting its heat-Seal Initiation Temperature (Tsi) up to 20 °C. Regarding the blends, incorporation of PBAT as a dispersed phase lowers Tsi of blend samples. Here, gradual decrease in PBAT crystallinity ca...

  • A novel approach toward the effect of Seal process parameters on final Seal strength and microstructure of LLDPE
    Journal of Adhesion Science and Technology, 2014
    Co-Authors: Zahra Najarzadeh, Abdellah Ajji
    Abstract:

    The optimization of heat-Sealing process parameters, including time, Temperature, and pressure, was performed on a monolayer linear low-density polyethylene (LLDPE) film. The Seal properties examined for each process condition were: Seal Initiation Temperature (Tsi), plateau Initiation Temperature (Tpi), final plateau Temperature (Tpf), plateau Seal strength (SSp), and failure mode. Increasing dwell time enhanced Seal strength. However, it was found that the rate of this enhancement is different for each interval of dwell time. A narrow Temperature plateau was observed for dwell times lower than 0.4 s and higher than 2 s, while in between a broad Temperature window was observed. The pressure shows its influence up to the stage of wetting. And after providing the intimate contact between two film layers, additional increase in pressure does not enhance Seal strength significantly. A 3D mapping of process safety zone was introduced for Seal strength in the range of heat Seal process variables for the very f...

  • Sealability and Seal Characteristics of PE/EVA and PLA/PCL Blends
    International Polymer Processing, 2014
    Co-Authors: Zahra Najarzadeh, Ramin Yousefzadeh Tabasi, Abdellah Ajji
    Abstract:

    Abstract Seal strength behavior of low density polyethylene and ethylene vinyl acetate copolymer (PE/EVA) blends as well as that of blends of a Seal grade PLA with aliphatic polyester (PCL) was studied. Polyethylene is commonly used for Seal application in packaging multilayer structures and amorphous PLA is considered to be its counterpart for compostable and/or biodegradables ones. Incorporation of EVA in polyethylene improves its Sealability in terms of a decrease in Seal Initiation Temperature and broadness of Sealability plateau. This was interpreted as due to the formation of finer crystals, a decrease in the melting point and presence of vinyl acetate polar group. These were supported by results obtained from differential scanning calorimetry (DSC) and Scanning electron microscopy (SEM). For the PLA/PCL system, the dispersed phase was stretched into elongated ellipsoidal domains. This type of morphology affected the mechanical and Seal properties of the blends. As a result of blending, both hot-tac...

  • Application of single site catalyst metallocene polyethylenes in extruded films: Effect of molecular structure on Sealability, flexural cracking and mechanical properties
    Canadian Journal of Chemical Engineering, 2014
    Co-Authors: F Sadeghi, Abdellah Ajji
    Abstract:

    Three single site catalysts metallocene polyethylenes (mPE) different in molecular structure were selected and films from them were produced using a semi-industrial cast film extrusion line. Rheological and gel permeation chromatography tests were performed on the mPE resins to assess their molecular structure. Mechanical, physical and Sealability properties of the films were evaluated as well as flexural cracking and particles encapsulation (caulkability) and the results are discussed in relation to the molecular structures of the resins. It was found that molecular weight and distribution of short chain branching (comonomer) on the backbone of the polyethylene chains are the main factors that control Sealability, flexural cracking and mechanical properties. The placement of comomoner on medium length chains generated crystals with smaller size that show a lower melting peak. Sealing was controlled by crystal distribution, chain diffusion and entanglement formation at the interface. mPE with lower melting point and linear molecular structure showed greater hot tack and Seal strength. Polydispersity along with molecular weight contributed to toughness and puncture resistance. Flexural cracking resistance was revealed to be related to crystallinity, tie chain density and more importantly to fraction of amorphous phase. The amorphous part could absorb flexural energy and hinders crack Initiation and propagation. Seal through contamination (caulkability) was found to be related to flowability of the melt. The resin with stronger shear thinning in melt state and lower heat Seal Initiation Temperature showed an improved caulkability.

Prasadarao Meka - One of the best experts on this subject based on the ideXlab platform.

  • heat Sealing of semicrystalline polymer films iii effect of corona discharge treatment of lldpe
    Journal of Applied Polymer Science, 1994
    Co-Authors: James M Farley, Prasadarao Meka
    Abstract:

    The effects of corona-discharge treatment (CDT) of commercial polyethylene (PE) Linear low-density PE (LLDPE) were studied with special emphasis on the heat-Seal behavior of treated films. A range of treat levels, representative of those used in industry, was obtained by varying the applied power to a commercial, on-line treater. Film surfaces were characterized by XPS and wetting-tension measurements. The primary effect of CDT on the heat-Sealing behavior of LLDPE films is a transition in the failure mode of heat Seals from a normal tearing or inseparable bond to a peelable Seal. In addition, CDT increases the Seal Initiation Temperature 5–17°C and decreases the plateau Seal strength 5–20% as the treat level, or wetting tension, increases from 31 to 56 dynes/cm. These effects are attributed to cross-linking during corona treatment, which restricts polymer mobility near the surface and limits the extent of interdiffusion and entaglements across the Seal interface. Results of heat-Sealing studies with electron-beam-irradiated PE, chemically oxidized PE, and CDT polypropylene (PP) provide indirect evidence for the proposed surface cross-linking mechanism. The effect of commercial levels of slip additives on the heat-Seal behavior was also investigated. © 1994 John Wiley & Sons, Inc.

  • Heat Sealing of semicrystalline polymer films. II. Effect of melting distribution on heat-Sealing behavior of polyolefins
    Journal of Applied Polymer Science, 1994
    Co-Authors: Ferdinand Christian Stehling, Prasadarao Meka
    Abstract:

    Heat Sealing of films, i. e., formation of a joint between two films by placing them fleetingly between heated platens, was experimentally investigated for a variety of semicrystalline polyolefins, especially various polyethlenes, to determine how Sealing Temperature affected Seal strength measured at room Temperature. Seal strength as a function of Sealing Temperature, SS(T), is closely related to the melting distribution of the polymer determined by DSC measurements, i. e., to the fraction of amorphous phase as a function of Temperature, fa(T). Seal Initiation Temperature, the Temperature at which a specific, low level of Seal strength of polyethylene films is achieved, corresponds to the Temperature at which the fraction of amorphous phase equals 77±3%. At higher Temperatures, SS(T) increases approximately as fa(T) increases. At the final melting point of the polymer, i.e., when fa(T) =1, Seal strength reaches an approximately constant value termed the plateau Seal strength. The magnitude of the plateau Seal strength is determined by the yield stress of the polymer film. Thus, the heat-Sealing curve, SS(T), for a polyethylene can be semiquantitatively predicted from the melting distribution and yield stress of the polymer. © 1994 John Wiley & Sons, Inc.