The effect of surface roughness and crystallinity on the light scattering of polyethylene tubular blown films

Larena, A.; Pinto, Gabriel

doi:10.1002/pen.760331204

Cited by 35 publications

(19 citation statements)

References 25 publications

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“…By recalling Eqs. (12) and (13) one, therefore, arrives at the following equivalent incoherent approximation to haze…”

Section: B a Naive Approximation To Hazementioning

confidence: 99%

“…For thin films, haze is recognized to be caused mainly by scattering from surface irregularities, in contrast to bulk randomness. Previously, only a few groups have reported on the dependence of haze on surface roughness [4,12,17]. In a study of different polyethylene materials, the bulk contribution to haze of 40µm thick films was found to vary in the range 10-30% of the total value [4].…”

Section: Introductionmentioning

confidence: 99%

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Haze of surface random systems: An approximate analytic approach

et al. 2009

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Approximate analytic expressions for haze (and gloss) of Gaussian randomly rough surfaces for various types of correlation functions are derived within phase-perturbation theory. The approximations depend on the angle of incidence, polarization of the incident light, the surface roughness, σ, and the average of the power spectrum taken over a small angular interval about the specular direction. In particular it is demonstrated that haze(gloss) increase(decrease) with σ/λ as exp(−A(σ/λ)2 ) and decreases(increase) with a/λ, where a is the correlation length of the surface roughness, in a way that depends on the specific form of the correlation function being considered. These approximations are compared to what can be obtained from a rigorous Monte Carlo simulation approach, and good agreement is found over large regions of parameter space. Some experimental results for the angular distribution of the transmitted light through polymer films, and their haze, are presented and compared to the analytic approximations derived in this paper. A satisfactory agreement is found. In the literature haze of blown polyethylene films has been related to surface roughness. Few authors have quantified the roughness and other have pointed to the difficulty in finding the correct roughness measure.

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“…By recalling Eqs. (12) and (13) one, therefore, arrives at the following equivalent incoherent approximation to haze…”

Section: B a Naive Approximation To Hazementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Haze of surface random systems: An approximate analytic approach

et al. 2009

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“…SAXS, how-The H v SALS pattern from the sample drawn at 45Њ to MD provides evidence for lamellar rota-ever, showed that the rotation occurred in the op-former is the predominant mechanism contributing to the V v scattering from blown films. 10,11 With this interpretation, the evolution of the V v SALS patterns may be interpreted straightforwardly. Initially, the surface bumps and irregularities must be randomly distributed and fairly circular for the isotropic scattering to arise.…”

Section: Salsmentioning

confidence: 99%

Real‐time in situ light scattering and X‐ray scattering studies of polyethylene blown film deformation

Butler

Donald

1998

J. Appl. Polym. Sci.

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A series of linear low-density polyethylene blown films were studied using the techniques of time-resolved, small-angle X-ray scattering (SAXS) using a synchrotron source and a time-resolved, small-angle light scattering. Scattering patterns and the load-extension curve were obtained simultaneously during deformation. It was found that the initial orientation of the film, with respect to the tensile axis, was important in determining the operative elastic deformation modes. Films drawn parallel to the machine direction (MD) showed evidence for lamellar separation, whereas interlamellar shear occurred in films drawn parallel to the transverse direction. In films drawn at 45Њ to MD, lamellar stack rotation was observed via SAXS. In all cases, the yield point corresponded to the activation of crystallographic deformation and the onset of the disruption of crystalline lamellae. In films drawn parallel to MD, the SAXS showed a distinct 4-point pattern upon macroscopic yield, indicating lamellar corrugation. Regardless of the initial orientation, a fibrillar morphology was achieved at some strain after yield that coexisted with the fragmenting lamellar morphology.Comparison of results from deformed spherulitic bulk samples showed that the study of oriented blown film containing a stacked lamellar morphology may be used, to a first approximation, as a model for the deformation of different regions of spherulites in unoriented spherulitic samples.

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“…, for an extremely smooth surface, incident light will be completely reflected at a certain angle, showing a high gloss effect. Whilst for a rough surface, much light is diffusely reflected instead of undergoing total reflection, thus achieving a matting effect. As for the transparency, it mainly depends on the refractive index of groups and the macromolecular chain crystallinity, with higher refractive index groups and crystallinity often resulting in a lower transparency …”

Section: Introductionmentioning

confidence: 99%

Synthesis of self‐matting waterborne polyurethane coatings with excellent transmittance

Sun

Fan

Chen

et al. 2017

Polymer International

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The effect of structural factors, including the type of diisocyanates and glycols, degree of crosslinking, hard-segment content, crystallinity and hydrophilic group content, on optical properties of waterborne polyurethane (WPU) was investigated. Based on the relationship between structure and properties, a series of self-matting WPUs with excellent transmittance were synthesized. Results demonstrated that refractive index of constituent groups was an important factor to influence the optical properties of coatings. For multiphase polyurethane, aromatic ring, ester bond, -NH-COO-and urea groups with high refractive index could decrease the matting effect and transmittance. Higher hard-segment content resulting in an increase of the number of -NH-COO-or urea bonds also decreased the matting effect and transmittance. The aggregation structure of WPU was another factor to influence the optical properties of coatings. Crystalline soft and hard segment domains could decrease the transmittance and matting effect, whilst non-crystalline segments, pendent groups and crosslinking destroyed the regularity or crystallinity of macromolecules, behaving as an auxiliary function to improve the transmittance. The particle size of WPU was of great importance for the matting effect. Smaller particle size (<5.0 m) would endow the coating with a smoother surface and higher reflected light ratio, and thus the expected matting effect was hard to be achieved. A larger particle size could improve the matting effect but impart to the coating a coarse surface and hand-feel. When the 2,2-bis(hydroxymethyl)propionic acid content was 1.6 wt%, spherical particles with a size distribution of 7-8 m were aggregated on the coating surface, giving the coating an excellent matting effect and hand-feel.

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The effect of surface roughness and crystallinity on the light scattering of polyethylene tubular blown films

Cited by 35 publications

References 25 publications

Haze of surface random systems: An approximate analytic approach

Haze of surface random systems: An approximate analytic approach

Real‐time in situ light scattering and X‐ray scattering studies of polyethylene blown film deformation

Synthesis of self‐matting waterborne polyurethane coatings with excellent transmittance

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