Wetting of Polymer Surfaces. I. Contact Angles of Liquids on Starch, Amylose, Amylopectin, Cellulose and Polyvinyl Alcohol

Ray, Bibek; Anderson, J. R.; Scholz, Juliane

doi:10.1021/j150568a015

Cited by 66 publications

(18 citation statements)

References 1 publication

(1 reference statement)

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“…P0 (pure cellulose) had an initial contact angle around 56°. This value was found to be higher than what is reported in the literature for cellulose films (32°) [55]. However, after some time ($1 min), the film started to absorb the water droplet.…”

Section: Pva-cellulose Compositescontrasting

confidence: 65%

Effect of trifluoroacetic acid on the properties of polyvinyl alcohol and polyvinyl alcohol–cellulose composites

Guzmán-Puyol

Ceseracciu

Heredia‐Guerrero

et al. 2015

Chemical Engineering Journal

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Section: Pva-cellulose Compositescontrasting

confidence: 65%

Effect of trifluoroacetic acid on the properties of polyvinyl alcohol and polyvinyl alcohol–cellulose composites

Guzmán-Puyol

Ceseracciu

Heredia‐Guerrero

et al. 2015

Chemical Engineering Journal

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“…Reports of a more polar nature of the cuticle over guard cells adjacent to the stomatal pore as indicated by staining behavior (17,26) do not necessarily contradict our conclusion because of the limited resolution of the light microscope. From our data there would appear to be very few hydroxyl groups exposed at the surface, as -CHg--CHOH-surfaces have been reported to have a critical surface tension between 35 and 42 dyne cm' (21).…”

Section: Resultsmentioning

confidence: 52%

Penetration of Stomata by Liquids

1972

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Wettability of the leaf surface, surface tension of the liquid, and stomatal morphology control penetration of stomata by liquids. The critical surface tension of the lower leaf surface of Zebrina purpusii Bruckn. was estimated to be 25 to 30 dyne cm-'. Liquids having a surface tension less than 30 dyne cm'i gave zero contact angle on the leaf surface and infiltrated stomata spontaneously while liquids having a surface tension greater than 30 dyne cm-' did not wet the leaf surface and failed to infiltrate stomata. Considering stomata as conical capillaries, we were able to show that with liquids giving a finite contact angle, infiltration depended solely on the relationship between the magnitude of the contact angle and the wall angle of the aperture. Generally, spontaneous infiltration of stomata will take place when the contact angle is smaller than the wall angle of the aperture wall. The degree of stomatal opening (4, 6, 8, or 10 /m) was of little importance.Cuticular ledges present at the entrance to the outer vestibule and between the inner vestibule and substomatal chamber resulted in very small if not zero wall angles, and thus played a major role in excluding water from the intercellular space of leaves. We show why the degree of stomatal opening cannot be assessed by observing spontaneous infiltration of stomata by organic liquids of low surface tension.tionship between any of these parameters and penetration has been generally poor. In this paper we present a systematic assessment of stomatal penetration by liquids based on the theory of capillary rise. THEORY When a liquid enters a capillary of circular cross-section the pressure difference (P) across the liquid meniscus is represented by equation 1,where '/L represents the surface tension of the liquid and R, and RI the principal radii of curvature of the liquid meniscus (1). In a narrow cylindrical capillary the meniscus is a segment of a sphere; R, and R, are equal and can be expressed in terms of the advancing contact angle (09) (4,22,27) unless external pressure is applied (6, 7). Some organic liquids, however, are known to penetrate readily, which led to attempts to estimate the degree of stomatal opening from substomatal penetration of certain organic liquids (18,22,25). Reports concerned with the effect of surfactants on promoting penetration into stomata and the substomatal space by aqueous solutions are contradictory (3, 4. 11, 14). Surface tension, viscosity, contact angle, diameter of the stomatal aperture, final height and initial velocity of capillary rise have been implicated in controlling penetration of liquids into the stomatal pore and substomatal chamber (4,6,7,18,26,27) A liquid will rise in the capillary spontaneously only if P is positive. The sign of P is determined by the term cos O.,; P being positive when OA < 90', zero when 9A = 900 and negative when O., > 900. The magnitude of P increases as r decreases.For a conical capillary (Fig. 1)

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“…12,13 In order to avoid this effect, we used the film surface which was opposite to the side contacting the glass plate during film preparation. Immediately prior to measurement, the films were re-dried under vacuum at 70 C for 12 h.…”

Section: Contact Anglementioning

confidence: 99%

Two Different Surface Properties of Regenerated Cellulose due to Structural Anisotropy

Yamane

Aoyagi

Ago

et al. 2006

Polym J

203

146

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ABSTRACT:Contact angles of water droplet on regenerated cellulose films as an index of wettability were positively correlated with the orientation of (1-10) crystal planes and crystallinity. Because hydroxyl groups of cellulose are located at the equatorial positions of glucopyranose rings, corresponding to the surface of (1-10) crystal planes, the hydrophilicity of the (1-10) surface is expected to be very high. It is natural, therefore, that higher planar orientation of (1-10) planes and crystallinity lead to higher density of hydroxyl groups on the surface of regenerated cellulose films resulting in higher wettability. In contrast, hydrogen atoms are located at the axial positions of the glucopyranose rings, corresponding to the surface of (110) planes. Thus, the (110) surface is expected to be hydrophobic, and the surface energy obtained by computer simulations was far lower than that of the (1-10) surface. This suggests that cellulose with complementary properties, i.e., hydrophobicity, may be created by structural controls such as reversing the planar orientation from (1-

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Wetting of Polymer Surfaces. I. Contact Angles of Liquids on Starch, Amylose, Amylopectin, Cellulose and Polyvinyl Alcohol

Cited by 66 publications

References 1 publication

Effect of trifluoroacetic acid on the properties of polyvinyl alcohol and polyvinyl alcohol–cellulose composites

Effect of trifluoroacetic acid on the properties of polyvinyl alcohol and polyvinyl alcohol–cellulose composites

Penetration of Stomata by Liquids

Two Different Surface Properties of Regenerated Cellulose due to Structural Anisotropy

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