The Experts below are selected from a list of 102 Experts worldwide ranked by ideXlab platform
Changchong Wu - One of the best experts on this subject based on the ideXlab platform.
-
Hot Tack of metallocene catalyzed polyethylene and low density polyethylene blend
Journal of Applied Polymer Science, 1999Co-Authors: Hsihsin Shih, Changmin Wong, Yuchi Wang, Chijou Huang, Changchong WuAbstract:Films made of metallocene catalyzed polyethylene (mPE), low-density polyethylene (LDPE), and their blend were prepared to investigate how LDPE influences the Hot Tack of film. Experimental results showed Hot Tack is independent of film thickness. The addition of 30 wt % of LDPE can increase the Hot Tack of mPE film. The thermograms of differential scanning calorimetry (DSC) suggest the respective partial melting and recrystallization of those smaller size crystals at the bond forming and joint fracture stages play very important roles. The large amount of partial melting and high flow may induce a higher degree of molecular diffusion. Higher residual crystallinity and recrystallization at the Hot Tack testing process may induce higher resistant to bond fracture. Those two positive influences show that the mPE/LDPE film has the higher Hot Tack. The evidence from optical (higher optical transmission and lower haze) as well as viscoelastic (higher storage modulus and lower melt viscosity) properties further support this hypothesis. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 1769–1773, 1999
-
Hot Tack of metallocene catalyzed polyethylene and low‐density polyethylene blend
Journal of Applied Polymer Science, 1999Co-Authors: Hsihsin Shih, Changmin Wong, Yuchi Wang, Chijou Huang, Changchong WuAbstract:Films made of metallocene catalyzed polyethylene (mPE), low-density polyethylene (LDPE), and their blend were prepared to investigate how LDPE influences the Hot Tack of film. Experimental results showed Hot Tack is independent of film thickness. The addition of 30 wt % of LDPE can increase the Hot Tack of mPE film. The thermograms of differential scanning calorimetry (DSC) suggest the respective partial melting and recrystallization of those smaller size crystals at the bond forming and joint fracture stages play very important roles. The large amount of partial melting and high flow may induce a higher degree of molecular diffusion. Higher residual crystallinity and recrystallization at the Hot Tack testing process may induce higher resistant to bond fracture. Those two positive influences show that the mPE/LDPE film has the higher Hot Tack. The evidence from optical (higher optical transmission and lower haze) as well as viscoelastic (higher storage modulus and lower melt viscosity) properties further support this hypothesis. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 1769–1773, 1999
Abdellah Ajji - One of the best experts on this subject based on the ideXlab platform.
-
Development of high performance sealable films based on biodegradable/compostable blends
Industrial Crops and Products, 2015Co-Authors: Ramin Yousefzadeh Tabasi, Zahra Najarzadeh, Abdellah AjjiAbstract:Abstract In this study, the seal behavior of toughened blends of poly(lactic acid) (PLA) and polycaprolactone (PCL) was investigated in details. The blended samples were prepared using melt blending in a twin-screw extruder and were processed in the form of cast films of about 30 μm in thickness. Scanning electron microscopy (SEM) study of the morphology of the blends shows that laminar morphology develops in blends of 20% and 40% dispersed phase. Analysis of the thermal behavior of the blends using DSC thermograms reveals significant effect of blending on hindering the crystallization of PCL, resulting in lower crystallinity for samples with high PLA content. Latter provide blends with more amorphous phase and chain mobility, which help lowering the Seal and Hot-Tack initiation temperatures. Blending is shown to decrease Seal and Hot-Tack initiation temperatures up to 30 °C compared to neat PLA. In addition, this technique is proven to be successful to increase the Hot-Tack strength of the blends to a comparative level to commercially available seal grade resins at about 1100 g/25.4 mm for PCL content of 40%. The results indicate that elongation at break increases from about 4% for pure PLA to almost 150% for the blend of 40% PCL and over 400% when PCL content reaches 60%. Higher toughness is an important property for a flexible package and prevents defects caused by its handling and storage conditions.
-
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, 2014Co-Authors: F. Sadeghi, Abdellah AjjiAbstract: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.
Hsihsin Shih - One of the best experts on this subject based on the ideXlab platform.
-
Hot Tack of metallocene catalyzed polyethylene and low density polyethylene blend
Journal of Applied Polymer Science, 1999Co-Authors: Hsihsin Shih, Changmin Wong, Yuchi Wang, Chijou Huang, Changchong WuAbstract:Films made of metallocene catalyzed polyethylene (mPE), low-density polyethylene (LDPE), and their blend were prepared to investigate how LDPE influences the Hot Tack of film. Experimental results showed Hot Tack is independent of film thickness. The addition of 30 wt % of LDPE can increase the Hot Tack of mPE film. The thermograms of differential scanning calorimetry (DSC) suggest the respective partial melting and recrystallization of those smaller size crystals at the bond forming and joint fracture stages play very important roles. The large amount of partial melting and high flow may induce a higher degree of molecular diffusion. Higher residual crystallinity and recrystallization at the Hot Tack testing process may induce higher resistant to bond fracture. Those two positive influences show that the mPE/LDPE film has the higher Hot Tack. The evidence from optical (higher optical transmission and lower haze) as well as viscoelastic (higher storage modulus and lower melt viscosity) properties further support this hypothesis. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 1769–1773, 1999
-
Hot Tack of metallocene catalyzed polyethylene and low‐density polyethylene blend
Journal of Applied Polymer Science, 1999Co-Authors: Hsihsin Shih, Changmin Wong, Yuchi Wang, Chijou Huang, Changchong WuAbstract:Films made of metallocene catalyzed polyethylene (mPE), low-density polyethylene (LDPE), and their blend were prepared to investigate how LDPE influences the Hot Tack of film. Experimental results showed Hot Tack is independent of film thickness. The addition of 30 wt % of LDPE can increase the Hot Tack of mPE film. The thermograms of differential scanning calorimetry (DSC) suggest the respective partial melting and recrystallization of those smaller size crystals at the bond forming and joint fracture stages play very important roles. The large amount of partial melting and high flow may induce a higher degree of molecular diffusion. Higher residual crystallinity and recrystallization at the Hot Tack testing process may induce higher resistant to bond fracture. Those two positive influences show that the mPE/LDPE film has the higher Hot Tack. The evidence from optical (higher optical transmission and lower haze) as well as viscoelastic (higher storage modulus and lower melt viscosity) properties further support this hypothesis. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 1769–1773, 1999
Jurkka Kuusipalo - One of the best experts on this subject based on the ideXlab platform.
-
The Effect of Flame Treatment on Surface Properties and Heat Sealability of Low-Density Polyethylene Coating
Packaging Technology and Science, 2012Co-Authors: Mikko Tuominen, M. Ek, P. Saloranta, Martti Toivakka, Jurkka KuusipaloAbstract:The target of this study is to investigate the correlation between surface properties and heat sealability of flame-treated low-density polyethylene (LDPE) coating because it is vital to know how to modify the surface properties of LDPE coating without losing the heat sealing properties. Flame treatment showed a significant effect on the heat sealing properties of LDPE-coated paper. For example, the heat sealing temperature of LDPE coating decreased or alternatively doubled, depending on the equivalence ratio (air–propane ratio) of flame treatment. In addition, the Hot Tack strength was significantly enhanced by flame treatment, which broadened the Hot Tack window of LDPE-coated paper. The reason for the heat sealing performance of flame-treated LDPE coating was believed to be related to the simultaneous reactions, that is, cross-linking and chain scission, occurring on the LDPE surface. The molecular weight of LDPE surface increased or decreased, depending on the dominating reaction during flame treatment. This affected the chain mobility and the amount of chain interdiffusion across the seal interface and finally defined the heat sealing performance of LDPE-coated paper. Copyright © 2012 John Wiley & Sons, Ltd.
-
PHB/V in Extrusion Coating of Paper and Paperboard—Study of Functional Properties. Part II
Journal of Polymers and the Environment, 2000Co-Authors: Jurkka KuusipaloAbstract:Extrusion coating experiments were carried out in the pilot line at Tampere University of Technology (Institute of Paper Converting). Commercially produced 3-hydroxybutyrate/3-hydroxyvalerate copolymer, commercial Finnish paper, and paperboard qualities were utilized as substrates. Functional properties, such as heat-sealing and Hot-Tack properties, pinhole density, and water vapor transmission rate were determined. PHB/V coatings exhibited approximately four–six times higher water vapor transmission rates (WVTR) than the corresponding LDPE coatings. The incorporation of wax or tall oil rosin into PHB/V improved its water vapor barrier. Curling of PHB/V was reduced by the addition of wax or tall oil rosin into the base polymer. PHB/V provided good heat-sealing characteristics at rather high sealing temperatures. Pinhole density was substantially reduced by using higher molecular weight PHB/V and by incorporating plasticizer into PHB/V.
Tim A. Osswald - One of the best experts on this subject based on the ideXlab platform.
-
Effect of Metallocene Polyethylene on Heat Sealing Properties of Low Density Polyethylene Blends
Journal of Plastic Film and Sheeting, 2000Co-Authors: Juan Diego Sierra, María Del Pilar Noriega, Tim A. OsswaldAbstract:Laminations made with blends of metallocene polyethylene (m-PE) and high-pressure low density polyethylene (LDPE) were prepared to investigate the effect of the former resin on heat sealing performance. According to various experimental studies of seal strength, Hot Tack and differential scanning calorimeter (DSC), it could be concluded that percentages around 15% of m-PE allow the obtainment of the optimal balance for heat sealing properties and cost. Using the interdiffusion theory of heat sealing, a thorough discussion of the results was done.