The Role of Interfacial Adhesion in Polymer Composites Engineered from Lignocellulosic Agricultural Waste

This paper presents a comprehensive study about the application of a lignocellulosic agricultural waste, sunflower husk in different polymer composites. Two types of milled sunflower husk with different geometrical factors were incorporated into polypropylene, low-density and high-density polyethylene, polystyrene (PS), glycol-modified polyethylene terephthalate (PETG) and polylactic acid (PLA). The filler content of the composites varied between 0 and 60 vol%. The components were homogenized in an internal mixer and plates were compression molded for testing. The Lewis–Nielsen model was fitted to the moduli of each composite series, and it was found that the physical contact of the filler particles is a limiting factor of composite modulus. Interfacial interactions were estimated from two independent approaches. Firstly, the extent of reinforcement was determined from the composition dependence of tensile strength. Secondly, the reversible work of adhesion was calculated from the surface energies of the components. As only weak van der Waals interactions develop in the interphase of polyolefins and sunflower husk particles, adhesion is weak in their composites resulting in poor reinforcement. Interfacial adhesion enhanced by specific interactions in the interphase, such as π electron interactions for PS, hydrogen bonds for PLA, and both for PETG based composites.

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Detachment of compliant films adhered to stiff substrates via van der Waals interactions: role of frictional sliding during peeling

Journal of The Royal Society Interface ◽

10.1098/rsif.2014.0453 ◽

2014 ◽

Vol 11 (97) ◽

pp. 20140453 ◽

Cited By ~ 14

Author(s):

Rachel R. Collino ◽

Noah R. Philips ◽

Michael N. Rossol ◽

Robert M. McMeeking ◽

Matthew R. Begley

Keyword(s):

Van Der Waals ◽

Van Der Waals Interactions ◽

Work Of Adhesion ◽

Interface Fracture ◽

Strong Function ◽

Frictional Sliding ◽

Fracture Models ◽

Synthetic Adhesives ◽

Interface Sliding

The remarkable ability of some plants and animals to cling strongly to substrates despite relatively weak interfacial bonds has important implications for the development of synthetic adhesives. Here, we examine the origins of large detachment forces using a thin elastomer tape adhered to a glass slide via van der Waals interactions, which serves as a model system for geckos, mussels and ivy. The forces required for peeling of the tape are shown to be a strong function of the angle of peeling, which is a consequence of frictional sliding at the edge of attachment that serves to dissipate energy that would otherwise drive detachment. Experiments and theory demonstrate that proper accounting for frictional sliding leads to an inferred work of adhesion of only approximately 0.5 J m −2 (defined for purely normal separations) for all load orientations. This starkly contrasts with the interface energies inferred using conventional interface fracture models that assume pure sticking behaviour, which are considerably larger and shown to depend not only on the mode-mixity, but also on the magnitude of the mode-I stress intensity factor. The implications for developing frameworks to predict detachment forces in the presence of interface sliding are briefly discussed.

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Influence of Surface Modifications on Interfacial Interaction of Zeolite Filled Polymer Composites

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.471-472.320 ◽

2011 ◽

Vol 471-472 ◽

pp. 320-324 ◽

Cited By ~ 1

Author(s):

N. Zaharri ◽

Nadras Othman ◽

Z.A. Mohd Ishak

Keyword(s):

Polymer Composites ◽

Interfacial Adhesion ◽

Ethylene Vinyl Acetate ◽

Standard Test ◽

Interfacial Interaction ◽

Uniaxial Tensile ◽

Uniaxial Tensile Test ◽

Filled Polymer ◽

Vinyl Silane ◽

Internal Mixer

Interfacial interaction in zeolite filled polymer composites was investigated in this study. Two types of polymer which are polypropylene (PP) and ethylene vinyl acetate (EVA) were used as matrix in the preparation of the composites. Moreover, different modifications of zeolite filled polymer composites such as zeolite surface treatment with vinyl silane and alkylammonium and also chemical crosslinking were done to improve the interfacial adhesion between zeolite and polymer matrix. The zeolite filled polymer composites were homogenized using Thermo Haake Polydrive internal mixer and then compression molded into sheets according to standard test specimen. Uniaxial tensile test was performed in order to evaluate the mechanical behavior of the composites. The obtained experimental data for ultimate stress was correlated with Pukanszky theoretical model. The experimental results for all systems of zeolite filled polymer composites showed a good fit to the Pukanszky model. Interfacial interaction for each system of zeolite filled polymer composites was theoretically evaluated by determining the parameter B through this model. The value of parameter B for all zeolite filled polymer composite systems differs significantly from one another thus suggesting the applicability of this Pukanszky model in characterizing the filler-matrix interfacial adhesion.

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Testing ecological release as a compensating mechanism for mass mortality in a keystone predator

Marine Ecology Progress Series ◽

10.3354/meps13227 ◽

2020 ◽

Vol 637 ◽

pp. 59-69 ◽

Cited By ~ 1

Author(s):

J Sullivan-Stack ◽

BA Menge

Keyword(s):

Community Dynamics ◽

Limiting Factor ◽

Sea Star ◽

Top Predator ◽

Oregon Coast ◽

Ecological Release ◽

Keystone Predator ◽

Pisaster Ochraceus ◽

Wasting Syndrome

Top predator decline has been ubiquitous across systems over the past decades and centuries, and predicting changes in resultant community dynamics is a major challenge for ecologists and managers. Ecological release predicts that loss of a limiting factor, such as a dominant competitor or predator, can release a species from control, thus allowing increases in its size, density, and/or distribution. The 2014 sea star wasting syndrome (SSWS) outbreak decimated populations of the keystone predator Pisaster ochraceus along the Oregon coast, USA. This event provided an opportunity to test the predictions of ecological release across a broad spatial scale and determine the role of competitive dynamics in top predator recovery. We hypothesized that after P. ochraceus loss, populations of the subordinate sea star Leptasterias sp. would grow larger, more abundant, and move downshore. We based these predictions on prior research in Washington State showing that Leptasterias sp. competed with P. ochraceus for food. Further, we predicted that ecological release of Leptasterias sp. could provide a bottleneck to P. ochraceus recovery. Using field surveys, we found no clear change in density or distribution in Leptasterias sp. populations post-SSWS, and decreases in body size. In a field experiment, we found no evidence of competition between similar-sized Leptasterias sp. and P. ochraceus. Thus, the mechanisms underlying our predictions were not in effect along the Oregon coast, which we attribute to differences in habitat overlap and food availability between the 2 regions. Our results suggest that response to the loss of a dominant competitor can be unpredictable even when based in theory and previous research.

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Healing Touch: Clothed Images of the Virgin in Early Modern Portugal

10.31338/2657-6015ik.29.7 ◽

2020 ◽

pp. 51-78

Author(s):

Diana Pereira

Keyword(s):

Early Modern ◽

Reciprocal Relationship ◽

Physical Contact ◽

Religious Art ◽

Healing Touch ◽

Devotional Art ◽

Healing Power ◽

The Many ◽

Santa Maria

Over the last decades there was a growing interest in religious materiality, miraculous images, votive practices, and how the faithful engaged with devotional art, as well as a renewed impetus to discuss the long-recognized association between sculpture and touch, after the predominance of the visuality approach. Additionally, the neglected phenomenon of clothing statues has also been increasingly explored. Based on the reading of Santuario Mariano (1707–1723), written by Friar Agostinho de Santa Maria (1642–1728), this paper will closely examine those topics. Besides producing a monumental catalogue of Marian shrines and pilgrimage sites, this source offers a unique insight into the religious experience and the reciprocal relationship between image and devotee in Early Modern Portugal, and is a particularly rich source when describing the believers’ pursuit of physical contact with sculptures. This yearning for proximity is partly explained by the belief in the healing power of Marian sculptures, which in turn seemed to be conveniently transferred to a myriad of objects. When contact with the images themselves was not possible, devotees sought out their clothes, crowns, rosary beads, metric relics, and so forth. Items of clothing such as mantles and veils were particularly used and so it seems obvious they were not mere adornments or donations, but also mediums and extensions of the sculptures’ presence and power. By focusing on the thaumaturgic role of the statues’ clothes and jewels, I will argue how the practice of dressing sculptures was due to much more than stylistic desires or processional needs and draw attention to the many ways believers engaged with religious art in Early Modern Portugal.

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Importance of Interfacial Adhesion Condition on Characterization of Plant-Fiber-Reinforced Polymer Composites: A Review

Polymers ◽

10.3390/polym13030438 ◽

2021 ◽

Vol 13 (3) ◽

pp. 438

Author(s):

Ching Hao Lee ◽

Abdan Khalina ◽

Seng Hua Lee

Keyword(s):

Thermal Properties ◽

Polymer Composites ◽

Interfacial Adhesion ◽

Fiber Reinforced Polymer ◽

Plant Fiber ◽

Plant Fibers ◽

Natural Plant ◽

Reinforced Polymer ◽

Fiber Reinforced Polymer Composites ◽

Adhesion Condition

Plant fibers have become a highly sought-after material in the recent days as a result of raising environmental awareness and the realization of harmful effects imposed by synthetic fibers. Natural plant fibers have been widely used as fillers in fabricating plant-fibers-reinforced polymer composites. However, owing to the completely opposite nature of the plant fibers and polymer matrix, treatment is often required to enhance the compatibility between these two materials. Interfacial adhesion mechanisms are among the most influential yet seldom discussed factors that affect the physical, mechanical, and thermal properties of the plant-fibers-reinforced polymer composites. Therefore, this review paper expounds the importance of interfacial adhesion condition on the properties of plant-fiber-reinforced polymer composites. The advantages and disadvantages of natural plant fibers are discussed. Four important interface mechanism, namely interdiffusion, electrostatic adhesion, chemical adhesion, and mechanical interlocking are highlighted. In addition, quantifying and analysis techniques of interfacial adhesion condition is demonstrated. Lastly, the importance of interfacial adhesion condition on the performances of the plant fiber polymer composites performances is discussed. It can be seen that the physical and thermal properties as well as flexural strength of the composites are highly dependent on the interfacial adhesion condition.

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Utilization of Polymer Concrete Composites for a Circular Economy: A Comparative Review for Assessment of Recycling and Waste Utilization

Polymers ◽

10.3390/polym13132135 ◽

2021 ◽

Vol 13 (13) ◽

pp. 2135

Author(s):

Hatem Alhazmi ◽

Syyed Adnan Raheel Shah ◽

Muhammad Kashif Anwar ◽

Ali Raza ◽

Muhammad Kaleem Ullah ◽

...

Keyword(s):

Polymer Composites ◽

Polymer Composite ◽

Circular Economy ◽

Agricultural Waste ◽

High Strength ◽

Supplementary Cementitious Materials ◽

Polymer Concrete ◽

Promising Alternative ◽

Detailed Review ◽

Comparative Review

Polymer composites have been identified as the most innovative and selective materials known in the 21st century. Presently, polymer concrete composites (PCC) made from industrial or agricultural waste are becoming more popular as the demand for high-strength concrete for various applications is increasing. Polymer concrete composites not only provide high strength properties but also provide specific characteristics, such as high durability, decreased drying shrinkage, reduced permeability, and chemical or heat resistance. This paper provides a detailed review of the utilization of polymer composites in the construction industry based on the circular economy model. This paper provides an updated and detailed report on the effects of polymer composites in concrete as supplementary cementitious materials and a comprehensive analysis of the existing literature on their utilization and the production of polymer composites. A detailed review of a variety of polymers, their qualities, performance, and classification, and various polymer composite production methods is given to select the best polymer composite materials for specific applications. PCCs have become a promising alternative for the reuse of waste materials due to their exceptional performance. Based on the findings of the studies evaluated, it can be concluded that more research is needed to provide a foundation for a regulatory structure for the acceptance of polymer composites.

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How the work of adhesion affects the mechanical properties of silica-filled polymer composites

Journal of Materials Science ◽

10.1007/bf00363434 ◽

1994 ◽

Vol 29 (9) ◽

pp. 2406-2416 ◽

Cited By ~ 53

Author(s):

S. W. Shang ◽

J. W. Williams ◽

K. -J. M. Söderholm

Keyword(s):

Mechanical Properties ◽

Polymer Composites ◽

Work Of Adhesion ◽

Filled Polymer

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The role of JrPPOs in the browning of walnut explants

BMC Plant Biology ◽

10.1186/s12870-020-02768-8 ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Shugang Zhao ◽

Hongxia Wang ◽

Kai Liu ◽

Linqing Li ◽

Jinbing Yang ◽

...

Keyword(s):

Tissue Culture ◽

Production Efficiency ◽

Phenolic Content ◽

Leaf Tissue ◽

Limiting Factor ◽

Mature Leaves ◽

Survival Percentage ◽

Highly Active ◽

Young Leaves

Abstract Background Tissue culture is an effective method for the rapid breeding of seedlings and improving production efficiency, but explant browning is a key limiting factor of walnut tissue culture. Specifically, the polymerization of PPO-derived quinones that cause explant browning of walnut is not well understood. This study investigated explants of ‘Zanmei’ walnut shoot apices cultured in agar (A) or vermiculite (V) media, and the survival percentage, changes in phenolic content, POD and PPO activity, and JrPPO expression in explants were studied to determine the role of PPO in the browning of walnut explants. Results The results showed that the V media greatly reduced the death rate of explants, and 89.9 and 38.7% of the explants cultured in V media and A media survived, respectively. Compared with that of explants at 0 h, the PPO of explants cultured in A was highly active throughout the culture, but activity in those cultured in V remained low. The phenolic level of explants cultured in A increased significantly at 72 h but subsequently declined, and the content in the explants cultured in V increased to a high level only at 144 h. The POD in explants cultured in V showed high activity that did not cause browning. Gene expression assays showed that the expression of JrPPO1 was downregulated in explants cultured in both A and V. However, the expression of JrPPO2 was upregulated in explants cultured in A throughout the culture and upregulated in V at 144 h. JrPPO expression analyses in different tissues showed that JrPPO1 was highly expressed in stems, young leaves, mature leaves, catkins, pistils, and hulls, and JrPPO2 was highly expressed in mature leaves and pistils. Moreover, browning assays showed that both explants in A and leaf tissue exhibited high JrPPO2 activity. Conclusion The rapid increase in phenolic content caused the browning and death of explants. V media delayed the rapid accumulation of phenolic compounds in walnut explants in the short term, which significantly decreased explants mortality. The results suggest that JrPPO2 plays a key role in the oxidation of phenols in explants after branch injury.

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Comparative investigation of lasing and amplification performance in cryogenic Yb:YLF systems

Applied Physics B ◽

10.1007/s00340-021-07588-8 ◽

2021 ◽

Vol 127 (3) ◽

Author(s):

Umit Demirbas ◽

Martin Kellert ◽

Jelto Thesinga ◽

Yi Hua ◽

Simon Reuter ◽

...

Keyword(s):

Continuous Wave ◽

Estimation Method ◽

Laser Cavity ◽

Comparative Investigation ◽

Limiting Factor ◽

Experimental Conditions ◽

Temperature Estimation ◽

Transverse Temperature ◽

First Time

AbstractWe present detailed experimental results with cryogenic Yb:YLF gain media in rod-geometry. We have comparatively investigated continuous-wave (cw) lasing and regenerative amplification performance under different experimental conditions. In the cw lasing experiments effect of crystal doping, cw laser cavity geometry and pump wavelength on lasing performance were explored. Regenerative amplification behavior was analyzed and the role of depolarization losses on performance was investigated. A recently developed temperature estimation method was also employed for the first time in estimating average crystal temperature under lasing conditions. It is shown that the thermal lens induced by transverse temperature gradients is the main limiting factor and strategies for future improvements are discussed. To the best of our knowledge, the achieved results in this study (375 W in cw, and 90 W in regenerative amplification) are the highest average powers ever obtained from this system via employing the broadband E//a axis.

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