Micromorphological Differences Research Articles

Biosystematics studies of endemic Thlaspi violascens Boiss. and T. densiflorum Boiss. & Kotschy: Highlights on molecular and morphological identification

This study focuses on differentiating the endemic species Thlaspi violascens and T. densiflorum, which exhibit similar macromorphological characteristics and population appearances with utilizing molecular, anatomical, and micromorphological methods. The complete chloroplast genomes of both species have been sequenced for the first time using next-generation sequencing technologies, allowing for high-resolution analysis of their phylogenetic relationships. The isolated chloroplast genomes measure 152,693 base pairs for T. violascens and 152,718 base pairs for T. densiflorum. Phylogenetic analysis shows that species within the Thlaspi genus are monophyletically distinct from other genera. Although the average nucleotide diversity between the two species is low, whole-genome sequencing-based Skmer analysis has successfully enabled high-resolution species-level discrimination. Anatomically, the two species differ in several aspects, including the type of petiole tip, abaxial surface outline, epidermal cell size and layer count, petiole thickness, vascular bundle number, midrib lobes, mesophyll cell types, and collenchyma layer count. Micromorphological differences are also evident in the primary structures of the anther and ovary, as well as the secondary structures of the sepal and style. Overall, the study concludes that chloroplast genome data, petiolar anatomical features, and floral micromorphological traits can effectively distinguish between T. violascens and T. densiflorum.

The era of cybertaxonomy: X-ray microtomography reveals cryptic diversity and concealed cuticular sculpture in Aphanerostethus Voss, 1957 (Coleoptera, Curculionidae).

Weevils represent one of the most speciose and economically important animal clades, but remain poorly studied across much of the Oriental Region. Here, an integrative revision of the Oriental, flightless genus Aphanerostethus Voss, 1957 (Curculionidae: Molytinae) based on X-ray microtomography, multi-gene DNA barcoding (CO1, Cytb, 16S), and traditional morphological techniques (light microscopy, dissections) is presented. Twelve new species, namely, A.armatus Lewis & Kojima, sp. nov., A.bifidus Kojima & Lewis, sp. nov., A.darlingi Lewis, sp. nov., A.decoratus Lewis & Kojima, sp. nov., A.falcatus Kojima, Lewis & Fujisawa, sp. nov., A.incurvatus Kojima & Lewis, sp. nov., A.japonicus Lewis & Kojima, sp. nov., A.magnus Lewis & Kojima, sp. nov., A.morimotoi Kojima & Lewis, sp. nov., A.nudus Lewis & Kojima, sp. nov., A.spinosus Lewis & Kojima, sp. nov., and A.taiwanus Lewis, Fujisawa & Kojima, sp. nov. are described from Japan, Taiwan, Vietnam, and Malaysia. A neotype is designated for A.vannideki Voss, 1957. The hitherto monotypic genus Darumazo Morimoto & Miyakawa, 1985, syn. nov. is synonymized under Aphanerostethus based on new morphological data and Aphanerostethusdistinctus (Morimoto & Miyakawa, 1985), comb. nov. is transferred accordingly. X-ray microtomography is successfully used to explore for stable interspecific differences in cuticular, internal and micro morphology. Remarkable species-specific sexual dimorphism in the metatibial uncus is described in seven of the newly described Aphanerostethus species and the evolution of this character is discussed.

Diploids and tetraploids of Acorus (Acoraceae) in temperate Asia are pseudocryptic species with clear differences in micromorphology, DNA sequences and distribution patterns, but shared pollination biology

AbstractCommonly considered bispecific, Acorus is one of the most phylogenetically isolated angiosperm genera that forms the order Acorales sister to the rest of the monocots. The Acorus calamus group is widely distributed in the Holarctic regions of Eurasia and America and has strong medicinal and other practical uses since prehistoric times. Earlier studies interpreted native diploids and invasive triploids occurring in North America as two species that differed in morphology and distribution ranges. In contrast, diploids, triploids, and tetraploids occurring in Eurasia are commonly interpreted as one species because they reportedly cannot be distinguished in collections. We resolve the controversy over taxonomic concepts between Eurasia and America and provide the first detailed multidisciplinary account of Acorus in temperate Asia. We used plastid and nuclear markers, leaf anatomy, seed micromorphology, pollen stainability, flow cytometry, and direct chromosome counts. Diploids and tetraploids show stable molecular and micromorphological differences. Triploids are their sterile hybrids, with the plastid genome inherited from the diploid parent. Diploids of America and Asia tend to differ in leaf characters. Coadaptative coexistence with pollinating beetles Platamartus jakowlewi and Sibirhelus corpulentus (Kateretidae) is conserved between diploids and tetraploids and over a distance of 4700 km between Japan and Western Siberia. Diploids are self‐compatible and can set seeds in the absence of kateretid beetles. Tetraploids are self‐incompatible and/or cannot set seeds in the absence of Platamartus and Sibirhelus. Diploids (A. americanus) and tetraploids (A. verus) are two biological species; the former has two subspecies. Acorus calamus should be restricted to triploids; it apparently first evolved in temperate Asia. Diploids mostly occur in much cooler climates than triploids and tetraploids. Accessions of A. verus and A. calamus from tropical Asia are apparently derived from ancient introductions. Our data provide a new framework for the pharmacological use of Acorus.

Effect of Deashing Treatment on Ash Fusion Characteristics of Biochar from Bamboo Shoot Shells.

To investigate the influence of deashing on fusion characteristics, a combined method of water and acid washing with different sequences (water washing followed by acid washing, and acid washing followed by water washing) was used to treat the biochar of bamboo shoot shells (BBSSs). The results show that deashing decreased the K content of the biochar from 50.3% to 1.08% but increased the Si content from 33.48% to 89.15%. The formation of silicates and aluminosilicates from alkali metal oxides with silicon was an inevitable result of ash phase transformation at the high temperatures used to improve the fusion temperature (>1450 °C). The thermochemical behavior of ash mainly occurs at 1000 °C. The deashing treatment significantly reduced the reaction intensity during the high-temperature process. This significantly increased the thermal stability of the ash. The adjustment of the washing sequence had a slight impact on the chemical compositions, but the differences in ash micromorphology were obvious. Deashing treatments with different washing sequences can significantly improve ash fusion properties effectively and reduce the risk of scaling, slagging, and corrosion. This study provides a new and reasonable strategy for the deashing of biochar to commercially utilize bamboo shoot shell resources.

A natural protein-related biopolymer film and its positive role in pearl brightening

To date, the external micromorphological differences among high-luster pearls and the precise relationship between the organic matrix covered on the external surface of pearl and its luster remain, to a large extent, unknown. Here, using scanning electron microscopy combined with energy-dispersive x-ray spectroscopy, infrared spectroscopy, and Raman spectroscopy, we comparatively investigated the multiscale surface characteristics of representative seawater-cultured pearls with different luster grades. The results showed that a natural protein-related biopolymer film of nano-thickness existed on the surface of high-luster pearls. Moreover, the biopolymer film and the microscale tablets self-assembled by aragonite nanoparticles, which serve as a nanoscale organic film and a microscale plane mirror, respectively, together play key roles in producing the excellent luster. In addition, the higher the content of organic matter covering the external surface of pearls, or the thicker the average thickness of the film, the smoother the surface and the better the luster of pearls. The findings substantially enhance our knowledge of the gemological and morphological characteristics of pearls and their corresponding natural brightening mechanism. Most importantly, this study not only provides some key guidelines on the daily maintenance of pearls and the optimization process for pearl brightening but also inspires optical functional material syntheses.

Farklı habitatlarda yayılış gösteren Tamarix tetrandra (Tamaricaceae) türünün karşılaştırmalı yaprak ve gövde anatomisi

In this study, the leaf and stem structure of Tamarix tetrandra Pallas ex. Bieb. species, which are distributed in riparian and salt marshes, were examined in terms of anatomical and micromorphological aspects. Specimens of the species have been preserved in 70% alcohol for anatomical study. Herbarium specimens were used for micromorphological studies. The studies showed that there were differences in anatomy and micromorphology. It was found that the stomata were embedded in the epidermis in the samples distributed in the salt marsh. In addition, stem epidermal cell length, sclerenchyma cell diameter, sieve tube cell diameter, and pith cell diameter were found to be greater in riparian species. In the correlation analysis, a positive correlation was observed between leaf lower surface stomata width and upper epidermis cell width, and between stem sclerenchymatic cell diameter and upper epidermis cell width in species distributed in salt marshes. The studies did not find intensive salt accumulation in the stem and leaf structures of the species that spread in the salt marsh. Salt uptake is thought to be inhibited in these species.

Comparative Morphology of Island and Inland Agastache rugosa and Their Gastroprotective Effects in EtOH/HCl-Induced Gastric Mucosal Gastritis.

Agastache rugosa Kuntze (Lamiaceae; Labiatae), a medicinal and functional herb used to treat gastrointestinal diseases, grows well both on islands and inland areas in South Korea. Thus, we aimed to reveal the morphological and micromorphological differences between A.rugosa grown on island and inland areas and their pharmacological effects on gastritis in an animal model by combining morphological and mass spectrophotometric analyses. Morphological analysis showed that island A.rugosa had slightly smaller plants and leaves than inland plants; however, the density of all types of trichomes on the leaves, petioles, and stems of island A.rugosa was significantly higher than that of inland plants. The essential oil component analysis revealed that pulegone levels were substantially higher in island A.rugosa than in inland A.rugosa. Despite the differences between island and inland A.rugosa, treatment with both island and inland A.rugosa reduced gastric damages by more than 40% compared to the gastritis induction group. In addition, expression of inflammatory protein was reduced by about 30% by treatment of island and inland A.rugosa. The present study demonstrates quantitative differences in morphology and volatile components between island and inland plants; significant differences were not observed between the gastritis-inhibitory effects of island and inland A.rugosa, and the efficacy of island A.rugosa was found to be similar to that of A.rugosa grown in inland areas.

Isolation and characterization of bacterial cellulose produced from soybean whey and soybean hydrolyzate

Soybean whey and soybean hydrolyzate can be used for the biotechnological production of high-value products. Herein, we isolate soybean whey (SW)-and soybean hydrolyzate (SH)-derived bacterial cellulose (BC, produced by kombucha) and characterize it by a range of instrumental techniques to reveal differences in micromorphology, crystallinity, and themal behavior. Studies have shown that the amounts of wet state BC produced from HS, SW and SH was 181 g/L, 47 g/L and 83 g/L, respectively. The instrumental analysis of BC, included SEM, AFM, FT-IR, XRD and TGA. It is shown that the FT-IR spectra of BC have a similar character, but we found differences in the micromorphology,crystallinity and thermal temperature of BC. The minimum average widths of the fibers produced from SH medium was 100 ± 29 nm. The CrI values of BC produced from SH medium was 61.8%. The maximum thermal degradation rate temperature of BC produced from SW medium was 355.73 °C. The combined results demonstrate that soybean industrial waste can be used as a cost-effective raw material for BC production.

A morphological, anatomical and palynological investigation on Delphinium cilicicumP.H. Davis & Kit Tanand D. petrodavisianum Ilarslan & Kit Tan

In the present study, the morphological, anatomical and palynological properties of endemic species Delphinium cilicicum P.H. Davis & Kit Tan and D. petrodavisianum İlarslan & Kit Tan belonging tothe genus Delphinium L., Ranunculaceae of Turkey were investigated. D. cilicicum and D. petrodavisianum are very similar morphologically. However, in our studies, it has been determined that there are some differences between the two species in terms of morphological, anatomical and palynological aspects. Based on the data obtained, the similarities and differences between two species were revealed. The cross-sections taken from the roots of two species have peridermis, cortex, vascular tissue and central region, in cross sections taken from the stem have epidermis, cortex, vascular bundle, and pith. In cross sections taken from the sepal and petal have lower and upper epidermis, parenchyma cells and tracheal cells. Through cross-sections of fruit, it was observed that there were two seeds in the fruit and the fruit wall was determined in two species. In palynological research, pollen size, P/E ratio, colpus size, intine-exine thicknesses, amb diameter and distance between colpus were measured. It was revealed that D. cilicicum and D. petrodavisianum had tricolpate, oblate-spheroidal pollen grains.The results obtained from the pollen grains were similar to each other in examined species. The fruits and seeds of two species were examined using SEM microscopy. Micromorphological differences and similarities were determined. The fruits of the species are follicle and globose. The seeds are yellowish brown, sub pyramidal and fine-grained ornamented. Bangladesh J. Plant Taxon. 30(1): 77-88, 2023 (June)

A Case Study of Leaf Wettability Variability and the Relations with Leaf Traits and Surface Water Storage for Urban Landscape Plants

Leaf wettability, the affinity of a leaf surface to water droplets, affects the interactions between leaves and external environments. This study aimed to determine the interspecific and seasonal variabilities of leaf wettability across 30 common landscape plants, and their relationships with leaf functional traits, surface micromorphology and rainfall interception in Hefei city, China. Results indicated that leaf wettability was species-specific, and the adaxial and abaxial contact angles ranged from 63° to 134° and 66° to 134°, respectively, with the adaxial surface proving more wettable. Leaf wettability gradually increased from spring to winter. Classification of life forms revealed that there were no significant wettability differences among trees, shrubs and herbs, and between evergreen and deciduous plants, but deciduous plants’ wettability increased more significantly in winter. Leaf wettability was not significantly correlated with any leaf functional traits. Single surface microscopic parameters also had low correlations with leaf wettability. Instead, the low-wettability species were found to possess more prominent epidermis cells, dense waxy layers or trichomes on leaf surfaces. Leaf wettability was the best predictor of surface rainwater storage within all functional traits. Our results highlighted that leaf wettability was variable between different species and growth periods due to micromorphological differences, and significantly affected rainfall interception at the leaf scale, which may have great significance for evaluating plant hydrological function in urban areas.

Scutellaria orientalis subsp. virens ve Scutellaria salviifolia üzerinde Anatomik, Mikromorfolojik, Karyolojik ve Biyokimyasal bir çalışma

In this study, the anatomical and micromorphological structure, karyological characteristics and biochemical content of Scutellaria orientalis subsp. virens and endemic Scutellaria salviifolia, whose distributions areas overlap, were compared. Some anatomical and micromorphological differences were observed on the taxa; scleranchymatic pericycle layer on the stem, stomata density, distribution of trichomes, as well as the main vascular bundle and general shape of the petiole. The chromosome numbers of both taxa were determined as 2n = 22. However, there was a difference between chromosome length range and total chromosome length. The chromosome numbers and chromosome morphologies of these species have been defined for the first time in this paper. Differences in biochemical content were observed between species. Chlorophyll a (Chl a), total chlorophyll (Total Chl), total carbohydrate and malondialdehyde (MDA) contents were determined higher in leaf and stem samples of S. orientalis subsp. virens than S. salviifolia. There was no significant difference between the two taxa in terms of chlorophyll b (Chl b) content. Carotenoid (Car) content was detected higher in leaves samples of S. orientalis subsp. virens, but no significant difference was found between stems samples. Also, the effect of taxa on biochemical contents in relation to the habitat they live in is given in this study.

Effect of auto-exhaust pollution on leaf anatomy and micromorphology of Pistacia vera L.

One of the important causes of air pollution is automobile emissions Automobile exhausts can be toxic and harmful to plants. In light of this, this study aimed to examine the anatomical and micromorphological effects of auto exhaust pollution on Pistacia vera L. (Pistachio), an important agricultural plant. Pistachio leaflet samples taken from heavy traffic areas and rural areas were compared anatomically and micromorphologically. Also, the data were statistically evaluated. As a result of the study, it was seen that there are anatomical and micromorphological differences between the plant in the rural area and the plant in the heavy traffic area in the city center where air pollution and the number of cars are high. In particular, significant differences were detected in the epidermis surface and cuticle structure, trichome cover, stomatal characteristics, as well as mesophyll width, and epidermis anticlinal outer wall width. As a result, the study revealed that the agriculturally important P. vera is affected by pollution anatomically and micromorphologically.

Uncertainty analysis in measurement of contact friction parameters of bolted joint interface

In the literature [1,2], a test apparatus was proposed for high-precision measurement of contact friction parameters based on piezoelectric actuator and laser vibrometer. Based on this test apparatus, five pairs of nominally identical bolted joint specimen were fabricated according to the same drawings and process, and they were assembled and tested using four test plans under two bolt preloads. The reassembly uncertainties of the test apparatus were taken into account to assess the variability of the test results and to analyse error sources. Then the influence of part-to-part differences of nominally identical specimen pairs on the contact friction parameters was investigated. Finally, the variability of contact parameters for rough surfaces and smooth surfaces were studied, which indicates that roughness has an important effect on the uncertainty of test results. The results in this paper suggest that the micro morphology of the contact interface has a significant effect on the tangential contact stiffness, followed by energy dissipation, and has less impact on the friction coefficient. Differences in mechanical properties of nominally identical joint structures caused by differences in micromorphology should be considered in the actual analysis.

Use of microstructural characteristics of pollen and pistil to identify olive cultivars in Southern Brazil

The olive crop has a large diversity in cultivars around the world, whose identification have been based on leaf, stem or fruit traits. However, these traits may be influenced by the environment, which has led to the misidentification of cultivars. The variability of the pistil and pollen structure under electron scanning and light microscopy were studied using the cultivars 'Arbequina', 'Arbosana', 'Frantoio', 'Koroneiki', 'Manzanilla de Sevilla' and 'Picual', cultivated in Southern Brazil. The aim was to find unique patterns for their identification. This type of study has not been carried out in the conditions of Southern Brazil, where the identification of commercial cultivars sometimes is complex and confusing. There were significant differences in the variables, showing uniformity within each cultivar in different locations. The principal component analysis indicated a separation of cultivars according to similarities or micromorphological differences in the pollen wall, area of the lumen and the structural elements of the tectum. For the analysis of the pistil, the separation was even clearer, each cultivar individually forming a cluster, using as characters the length of the style in contrast to the length, width and area of the stigma. This evidenced little variation among individuals within the same cultivar. The information provided can contribute to the individual identification of very close olive tree cultivars in the conditions of Southern Brazil.

Gender-specific differences in micro-morphology, secondary metabolites, antioxidant and antimicrobial activity of wild Dioscorea species

Gender-specific differences in micro-morphology, secondary metabolites, antioxidant and antimicrobial activity of wild Dioscorea species

Accuracy of Original vs. Non-Original Abutments Using Various Connection Geometries for Single Unit Restorations: A Systematic Review.

To ascertain whether the compatibility of non-original abutments (NOAs) with dental implants is influenced by the type of implant connection, i.e.- internal or external, and whether certain combinations of componentry may be as compatible as the original components. A structured literature search was conducted using 3 electronic databases (MEDLINE® , The Cochrane Library, and Web of Science Core Collection) for studies reporting on the use of non-original abutments published between 1995 and 2020. This was supplemented with hand searching in relevant journals and references, as well as searching grey literature. Relevant studies were selected according to specific inclusion criteria. Data was collected for the following parameters: precision of fit, microleakage, micromorphological differences, micromotion, rotational misfit, screw loosening, maximum load capacity, fracture resistance, tensile strength, compressive strength and invivo implant and prosthesis outcomes. The electronic search and hand search yielded titles and abstracts of 5617 studies following de-duplication; based on the eligibility criteria, 40 studies were finally selected. Overall, original abutments showed better precision of fit, ability to resist microleakage, prevention of rotational misfit and micromotion, and fatigue strength compared with non-original abutments. Some non-original abutments on external connections were comparable with original abutments in terms of precision of fit and resistance to screw loosening and may be associated with less catastrophic failures than those on internal connections. Original abutments present more predictable outcomes than non-original abutments with regards to the parameters investigated. However, it seems that external connections can provide some level of compatibility in terms of precision of fit and may also exhibit less catastrophic failures than NOAs on internal connections. This may be due to the increased rotational freedom external connections provide. There is a lack of information regarding the influence of connection geometry on many aspects of compatibility and therefore the current clinical recommendation should be to use original abutments. More laboratory studies comparing non-original abutments on different implant connections are required. In addition, there is a need for long-term in vivo studies providing data on the clinical performance of non-original abutments.

Comparative Study of Conocarpus erectus and Phoenix dactylifera as Plant Biomonitors of Particulate Matter Pollution in Kuwait over Three Land Use Classes

Magnetic plant biomonitoring has been proven to be an effective tool in the assessment of air quality. Kuwait presents a unique environment due to its dry desert climatic conditions and prevailing dry deposition patterns that may affect accumulation rates of magnetic mineral particles. This study evaluated two widely distributed ornamental species, buttonwood (Conocarpus erectus) and palm (Phoenix dactylifera) for their effectiveness as biomagnetic monitors over three different land use classes (urban, suburban and industrial land classes). The differences between land use classes were classified by their proximity to major pollution sources as well as population density. Leaf sampling was conducted over various heights and distances from the nearest road. Total leaf saturated isothermal magnetization (SIRM), hard isothermal magnetization (HIRM), hard isothermal magnetization percentage (HIRM%) and s-ratio have been measured. Scanning electron microscopy (SEM) was used to analyze leaf surface micromorphology. It was determined that NRM values are similar for all land use classes and species, ranging from 0.3 to 0.5 μA. Palm leaf overall magnetic concentration was identified to be higher at the industrial land use class than at the urban land use class, indicating high coercivity minerals to magnetically dominate the land use classes. Additionally, total leaf SIRM was determined to be higher at short distances of 0 - 5 meters from the vicinity of the road. The surface rugosity of palm has deep ridges and furrows with ununiform wax projections across the leaf surface, while buttonwood has a smooth wax film with low relief. Differences in leaf micromorphology in addition to plant physiology, justify species magnetic parametric variances. Palm leaf had an average SIRM value that is 120% higher than buttonwood. It has been highlighted that through the application of the magnetic parameter results to spatial distribution maps that there is an association between particulate matter (PM) and the locality of main roads and local services that may experience higher intensities of traffic.

Micromorphological Characteristics of Fruit Surfaces of Some Usable Species of the Genus Valeriana (Valerianaceae) Among Ukrainian Flora

Abstract The micromorphological features of the fruit surfaces of nine species of Ukrainian flora, namely Valeriana tuberosa L., Valeriana tripteris L., Valeriana rossica P. Smirn., Valeriana stolonifera Czern., Valeriana grossheimii Worosch, Valeriana sambucifolia Mikan fil., Valeriana officinalis L. s. str., Valeriana wolgensis Kazak. [ Valeriana officinalis var. nitida (Kreyer) Rostanski], and Valeriana simplicifolia (Rchb.) Kabath, were examined. Depending on the presence and localization of pubescence on the surface of the fruit, three groups of species were distinguished: those with glabrous fruits, those with fruits pubescent only on the adaxial side, and those with fruits pubescent on both sides. Scanning electron microscopy revealed the additional characteristics of the fruits (microsculpture of the fruit surface, shape of cuticular formations on the surface of the outer periclinal walls of epidermal cells and on the surface of hairs, and structure of the stomatal complex), which were useful for the identification of the species. At the supraspecific level, the revealed features of the fruit surfaces somewhat overlapped and could be used to identify series and sections only as additional features. Based on the studied samples from herbarium material (KW), V. officinalis var. nitida was considered synonymous with V. wolgensis since there were no micromorphological differences between their fruits. The detailed micromorphological characteristics of the fruit surfaces of all the studied species can be used for further comparative morphological investigations of different aerial parts to identify stable features independent of geographic and ecological conditions.

Is the Er:YAG laser affect the surface characteristics and bond strength of Y-TZP?

This study evaluated the surface characteristics and bond strength of Y-TZP treated with Er:YAG laser at different focal distances. 120 Y-TZP blocks were divided into five groups (n=24), according to the surface treatment: no treatment (C-); sandblasting with silica-coated aluminum oxide particles (C+); and Er:YAG laser application at focal distances of 1mm (Er:YAG-1), 4mm (Er:YAG-4), and 7mm (Er:YAG-7). Surface characteristics were analyzed using Vickers microhardness, confocal laser microscope, scanning electron microscopy (SEM), and X-ray diffractometer (XRD). For the bond strength test, 100 Y-TZP blocks were subdivided into two subgroups (n=10), according to the resin cement used: with (MDP+) or without 10-methacryloyloxydecyl dihydrogen phosphate (MDP-). The Vickers microhardness and surface roughness were analyzed by one-way ANOVA and bond strength by two-way ANOVA and Tukey's test for both (α=0.05). Vickers microhardness differences were not observed between the groups (p>0.05); C+ showed higher surface roughness values. SEM images showed micromorphological differences between the groups. The XRD data detected tetragonal crystals for C- and, for the other groups, tetragonal and monoclinic peaks. For bond strength, no statistically difference significance were observed among the cements with or without MDP (p>0.05) but showed significant difference between the surface treatments (C+ > C- = Er:YAG1 > Er:YAG4 = Er:YAG7) (p<0.05). Suggested that the Er:YAG laser cannot replace conventional treatment with aluminum oxide particles and the presence of MDP in the resin cement had no influence on the bond strength.

Expanded vermiculite-filled flexible polymer composites

This study focuses on the fabrication and characterization of vermiculite-filled flexible polymer composites. Exfoliated vermiculite was incorporated into triblock thermoplastic elastomer copolymer, styrene- b-(ethylene- co-butylene)- b-styrene (SEBS), at various levels from 1 to 15 wt% by a high shear mixer. The composite films were obtained by the combination of solvent casting and compression molding. The morphological, structural, thermal, and mechanical properties and contact angle of the composites were determined. Some micro-morphological differences were observed between the samples and the difference was assumed to be caused by high shear mixing and filler concentration. High shear mixing was found effective in terms of the detachment of vermiculite layers at all concentrations. However, at low filler loading, that behavior was more obvious. At 1 wt% filler concentration, mechanical properties increased that was probably caused by good filler-matrix interaction stemmed from smaller particle size. At higher vermiculite concentrations, fillers found to show agglomerations that led to a decrease in mechanical strength and strain at break. Elastic and secant modulus showed an increasing trend. Contact angle measurements were carried out to determine the oleophilic character of the samples. An increase in the vermiculite content resulted in higher oleophilic character and the lowest contact angle was obtained at 15 wt% VMT loading. In addition to these, thermal stability, thermal dimensional stability and flame retardancy were improved by the incorporation of VMT. 15 wt% vermiculite-filled sample showed the best performance in terms of thermal stability and flame retardancy.