Optical properties of blown and cast polyethylene films: Surface versus bulk structural considerations

Johnson, Matthew B.; Wilkes, Garth L.; Sukhadia, Ashish M.; Rohlfing, David C.

doi:10.1002/1097-4628(20000923)77:13<2845::aid-app6>3.3.co;2-z

Cited by 21 publications

(40 citation statements)

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“…Islands of crystal domains in the amorphous ocean were thought to be mainly account for higher haze [2,8,20], however, this viewpoint is untenable in the case of LDPE blown films based on our experiments. The DSC exothermic curves for LDPE films are presented in Fig.…”

Section: Relationship Between Haze and Microstructure In Ldpe Filmsmentioning

confidence: 61%

“…The haze of a film is defined as the fraction of (normal incident) transmitted light that deviates from the directly transmitted beam by more than 2.5 [1]. For blown LDPE films, haze may originate from light scattering caused by both bulk inhomogeneities and surface roughness [2]. It was recognized in the early time that haze was caused primarily by the light scattering due to surface irregularities [3e6].…”

Section: Introductionmentioning

confidence: 99%

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Influence of molecular architecture and melt rheological characteristic on the optical properties of LDPE blown films

Zhu

Wang

Zhang

et al. 2007

Polymer

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Section: Relationship Between Haze and Microstructure In Ldpe Filmsmentioning

confidence: 61%

Section: Introductionmentioning

confidence: 99%

Influence of molecular architecture and melt rheological characteristic on the optical properties of LDPE blown films

Zhu

Wang

Zhang

et al. 2007

Polymer

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“…At levels of mLLDPE above this maximum, there is a noticeable increase in the haze and a corresponding decrease in the gloss. The decline in optical properties that is observed at levels of mLLDPE above 40 wt.% may be due to melt fracture that occurs in the blend as a result of the processing conditions [46][47][48][49][50]. …”

Section: Fast-rate Large Deformation Mechanical Propertiesmentioning

confidence: 99%

The Effect of Downgauging on the Physicomechanical Properties of Film Blends of Linear Low-density Polyethylene with Low-density Polyethylene

Cran

Bigger

2005

Journal of Elastomers & Plastics

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Two series of film formulations are investigated comprising blends of a metallocene-catalyzed linear low-density polyethylene (mLLDPE) or a conventional linear low-density polyethylene (LLDPE) with a low-density polyethylene (LDPE). The physicomechanical and optical properties are studied at various gauge lengths to investigate the effects of downgauging the films, particularly those containing mLLDPE. The potential for downgauging is found to be optimum at higher levels of mLLDPE with the best results achieved for a film containing 40 wt.% mLLDPE at 60 mm. This formulation has significantly better properties than an analogous blend containing 40 wt.% LLDPE at 100 mm. The potential materials and cost savings associated with downgauging films is also briefly investigated.

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“…Several publications [5,[7][8][9][10][11][12][13][14] have shown that a primary cause of poor optical properties in blown polyethylene (PE) films is the surface roughness and the asperities present on the surfaces and that the orientation states of the crystalline and amorphous phases largely dictate the performance of blown films and their application.…”

Section: Introductionmentioning

confidence: 99%

“…Few studies have also concentrated on the control of optical properties of films, which are important factors for the application in packaging market. Johnson et al [7] in their extensive work have stated that the mLLDPE grade with low elasticity and recoverable shear (due to narrow molecular weight distribution and general lack of any long chain branching) could present in the melt, during crystallization, residual orientation, that promotes the formation of spherulitic-like superstructure during the blowing process. The presence of spherulitic structures in the blown films enhances the roughness of the surfaces and causes high haze value.…”

Section: Introductionmentioning

confidence: 99%

Structure and Morphology Development in Films of mLLDPE/LDPE Blends During Blowing

Silvestre

Cimmino

Raimo

et al. 2006

Macro Materials & Eng

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Summary: In this work the analysis of the structure orientation, morphology, relaxation time and optical properties of blown films of mLLDPE, LDPE and their blends were performed by using WAXD, SALS, AFM, DSC and rheological and haze tests. For mLLDPE film, the crystals do not present “a”‐axis orientation along the machine direction; a distinct spherulite like superstructure is seen. The film surface is very rough. The values of bulk and surface haze are higher than LDPE and blends, whereas the relaxation time is lower. For LDPE film the (110) planes are parallel and at same time twisted with respect to the layer of the film with the “a”‐axis well oriented along the machine direction. No spherulite superstructure is observed and the surface of the film is more regular. High values of relaxation time are observed. The surface haze is the predominant contribution to the total haze. For the blend films no clear and distinct spherulite structures are observed. The orientation degree increases with composition never approaching that of LDPE. The surface is very more regular and smooth than that of the pure polymers. The haze values are below the values of pure materials. It was underlined that bulk and surface morphology and orientation degree of the crystalline planes along the machine direction dictate the optical properties of the films. Moreover both orientation and morphology are defined by the PE molecular and melt rheology characteristics, processing conditions and blend composition.Total, bulk and surface haze of mLLDPE/LDPE blend films as a function of composition.magnified imageTotal, bulk and surface haze of mLLDPE/LDPE blend films as a function of composition.

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Optical properties of blown and cast polyethylene films: Surface versus bulk structural considerations

Cited by 21 publications

References 0 publications

Influence of molecular architecture and melt rheological characteristic on the optical properties of LDPE blown films

Influence of molecular architecture and melt rheological characteristic on the optical properties of LDPE blown films

The Effect of Downgauging on the Physicomechanical Properties of Film Blends of Linear Low-density Polyethylene with Low-density Polyethylene

Structure and Morphology Development in Films of mLLDPE/LDPE Blends During Blowing

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