scholarly journals Study of Aquilaria crassna Wood as an Antifungal Additive to Improve the Properties of Natural Rubber as Air-Dried Sheets

Polymers ◽  
2021 ◽  
Vol 13 (23) ◽  
pp. 4178
Author(s):  
Phattarawadee Nun-Anan ◽  
Sunisa Suchat ◽  
Narissara Mahathaninwong ◽  
Narong Chueangchayaphan ◽  
Seppo Karrila ◽  
...  
Keyword(s):  
Natural Rubber ◽  
Fungal Growth ◽  
Physical And Mechanical Properties ◽  
Significant Inhibition ◽  
Added Value ◽  
High Plasticity ◽  
Green Strength ◽  
Unpleasant Odor ◽  
Negative Impacts ◽  
Aquilaria Crassna

Fungal growth on rubber sheets confers inferior properties and an unpleasant odor to raw natural rubber (NR) and products made from it, and it causes environmental concerns. The purpose of the present work was to investigate the effects of Aquilaria crassna wood (ACW) on the antifungal, physical and mechanical properties of NR as air-dried sheets (ADS) and ADS filled with ACW. The results show that the ACW-filled ADS had an increased Mooney viscosity, initial plasticity (PO), and high thermo-oxidation plasticity (i.e., high plasticity retention index PRI). Additionally, superior green strength was observed for the ACW-filled ADS over the ADS without additive because of chemical interactions between lignin and proteins in NR molecules eliciting greater gel formation. A significant inhibition of fungal growth on the NR products during storage over a long period (5 months) was observed for ACW-filled ADS. Thus, it can be concluded that ACW could be applied as an antifungal additive that reduces fungal growth. This is a practically important aspect for the rubber industry, as fungal growth tends to spoil and cause the loss of NR sheets during storage. Moreover, the ACW is active as an incense agent, reducing negative impacts from odors that fungi, on rubber surfaces, release. Therefore, these filled intermediate NR products provide added value through, an environmentally friendly approach, this is pleasant to customers.

scholarly journals Composites from Thermoplastic Natural Rubber Reinforced Rubberwood Sawdust: Effects of Sawdust Size and Content on Thermal, Physical, and Mechanical Properties

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Chatree Homkhiew ◽  
Surasit Rawangwong ◽  
Worapong Boonchouytan ◽  
Wiriya Thongruang ◽  
Thanate Ratanawilai
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Natural Rubber ◽  
High Density Polyethylene ◽  
High Performance ◽  
Physical And Mechanical Properties ◽  
Modulus Of Rupture ◽  
Shore Hardness ◽  
Thermoplastic Natural Rubber ◽  
Plastic Content

The aim of this work is to investigate the effects of rubberwood sawdust (RWS) size and content as well as the ratio of natural rubber (NR)/high-density polyethylene (HDPE) blend on properties of RWS reinforced thermoplastic natural rubber (TPNR) composites. The addition of RWS about 30–50 wt% improved the modulus of the rupture and tensile strength of TPNR composites blending with NR/HDPE ratios of 60/40 and 50/50. TPNR composites reinforced with RWS 80 mesh yielded better tensile strength and modulus of rupture than the composites with RWS 40 mesh. The TPNR/RWS composites with larger HDPE content gave higher tensile, flexural, and Shore hardness properties and thermal stability as well as lower water absorption. The TPNR/RWS composites with larger plastic content were therefore suggested for applications requiring high performance of thermal, physical, and mechanical properties.

scholarly journals Rapidly dissolving microneedle patch of amphotericin B for intracorneal fungal infections

2021 ◽  
Author(s):  
Alyaa A. Albadr ◽  
Ismaiel A. Tekko ◽  
Lalitkumar K. Vora ◽  
Ahlam A. Ali ◽  
Garry Laverty ◽  
...  
Keyword(s):  
Fungal Infection ◽  
Amphotericin B ◽  
Fungal Infections ◽  
Fungal Growth ◽  
Significant Inhibition ◽  
Corneal Tissue ◽  
Biodegradable Poly ◽  
Invasive Method ◽  
Poorly Soluble ◽  
Microneedle Patch

AbstractChronic fungal infection of the cornea could lead to blindness if not treated properly. Topical amphotericin B (AMP-B) is considered the first treatment of choice for ocular fungal infection. However, factors related to its poor solubility and penetration through intact cornea lead to poor bioavailability. Microneedles (MNs) are emerging as a minimally invasive method to enhance ocular drug delivery. This study aims to investigate the potential use of biodegradable poly(vinylpyrrolidone) (PVP) and hyaluronic acid (HA)–based rapidly dissolving MNs for delivery of AMP-B to treat fungal infection. The data obtained illustrates PVP/HA MN arrays’ reproducibility, good mechanical strength, and faster dissolution with 100% drug recovery. Multiphoton microscopic results revealed that MNs successfully penetrate the corneal tissue and enhance AMP-B permeation through corneal layers. Furthermore, PVP/HA MN arrays showed high solubility. Both PVP and HA successfully decreased AMP-B cytotoxicity when compared to free drug. More interestingly, the biocompatible MN formulations preserved the antifungal activity of AMP-B, as demonstrated by significant inhibition of fungal growth. Therefore, this study shows the feasibility of ocular delivery of the poorly soluble AMP-B using a fast-dissolving MN patch. Graphical abstract

STUDY OF AMINO ACID MODIFIERS IN GUAYULE NATURAL RUBBER

2015 ◽  
Vol 88 (2) ◽  
pp. 310-323 ◽  
Author(s):  
Colleen McMahan ◽  
Dhondup Lhamo
Keyword(s):  
Amino Acids ◽  
Natural Rubber ◽  
Oxidative Stability ◽  
Chemical Properties ◽  
The United States ◽  
Thermal Oxidative Stability ◽  
Green Strength ◽  
Strain Induced Crystallization ◽  
New Perspective ◽  
Physical And Chemical

ABSTRACT Guayule, a desert shrub indigenous to the United States, is under development as a source of natural rubber that can be used in place of petroleum-based rubber or Hevea rubber. In natural rubbers, physical and chemical properties can be strongly affected by nonrubber constituents, typically proteins and lipids, present in the material, depending on the plant species and postharvest processing. Hevea natural rubber typically contains high levels of nonrubber constituents that contribute to thermal-oxidative stability, cure acceleration, and especially strain-induced crystallization. The latter has been attributed to compound properties that render Hevea natural rubber uniquely suited for the most demanding rubber applications (e.g., aircraft tires). Hevea proteins are susceptible to hydrolysis, releasing free amino acids into the latex, which can affect rubber and compound properties. Here, low-protein guayule latex was blended with a series of amino acids varying in chemical structure. Bulk viscosity was reduced, thermal-oxidative stability was improved, and cure rate was influenced by the addition of amino acids. Generally, gel formation, green strength, and tensile strength were not affected. The results introduce a new perspective for amino acids as biobased rubber compound additives and provide insights into naturally occurring nonrubber constituents' interaction with natural rubber polymers.

Test trials of a process to produce briquettes from coal mining waste

2021 ◽  
pp. 93-96
Author(s):  
T. A. Ketegenov ◽  
K. Kamunur ◽  
T. I. Yushina ◽  
S. N. Kalugin
Keyword(s):  
Fine Fraction ◽  
Physical And Mechanical Properties ◽  
Added Value ◽  
Coal Waste ◽  
Chemical Processing ◽  
Ministry Of Education ◽  
Production Wastes ◽  
Grant Support ◽  
National University ◽  
Coal Fines

At the present time, coal production wastes up to 2 % of fine fraction, which has adverse impact on the environment. On the other hand, coal fines can be a feedstock to obtain different products of chemical processing—benzines, oils, briquettes, etc. For this reason, it is necessary to develop dedicated technologies to utilize fine waste in manufacture of products having high added value. The experimental results demonstrate usability of wheat bran as a binder in coal waste briquetting. It is found how the binder and the briquetting conditions influence the physical and mechanical properties and combustion characteristics of coal briquettes. The optimized coal briquetting conditions are: carbonization of feedstock, use of binder in quantity of 25–30 mass%, briquetting pressure of 4 MPa. Thus, the authors have analyzed the influence of the briquetting conditions on the properties of coal briquettes, and have tested the earlier developed approaches to transformation of Oi-Karagai coal fines into a target product of high added value. The authors appreciate participation of A. Karagulanov, fellow of the Al-Farabi Kazakh National University in this study. The work was performed with the grant support of the Ministry of Education and Science RK-A RO 08957618.

Physical and mechanical properties of compounded hydroxylated natural rubber

2018 ◽  
Author(s):  
Nurul Wahidah Zahari ◽  
Ahmad Faiza Mohd ◽  
Azemi Samsuri ◽  
Dzaraini Kamarun
Keyword(s):  
Mechanical Properties ◽  
Natural Rubber ◽  
Physical And Mechanical Properties

EFFECT OF PROTEIN ADDITION ON PROPERTIES OF GUAYULE NATURAL RUBBER

2017 ◽  
Vol 90 (2) ◽  
pp. 387-404 ◽  
Author(s):  
Dhondup Lhamo ◽  
Colleen McMahan
Keyword(s):  
Amino Acids ◽  
Natural Rubber ◽  
Oxidative Stability ◽  
Chemical Properties ◽  
Green Strength ◽  
Truck Tires ◽  
Oxidative Resistance ◽  
Strain Induced Crystallization ◽  
General Protein ◽  
Physical And Chemical

ABSTRACT Parthenium argentatum, commonly known as guayule, is a desert shrub cultivated as a domestic source of natural rubber in the semi-arid southwestern United States. Guayule natural rubber (GR) may be used to replace petroleum-based rubber or in place of Hevea natural rubber (NR), but substitution must take into consideration differences in physical and chemical properties. Currently, Hevea NR is required in tire applications, especially aircraft and truck tires, because of its high oxidative resistance, rapid cure rate, and exceptional stress–strain response. These outstanding features are attributed to the presence of nonrubber constituents, mainly proteins and lipids, which cause the rubber to gel, and they contribute to strain-induced crystallization. In contrast, GR is low in proteins and is thus deprived of some attributes of Hevea. Addition of amino acids and proteins to guayule could potentially improve performance and thereby widen the range of applications for use. In a previous study, amino acids blended with GR latex improved thermo-oxidative stability, served as plasticizers and cure accelerators, and enhanced green strength slightly, but tensile strength was not improved. Here, a series of bio-based commercial proteins (gelatin, soy, albumin, casein, zein, gliadin, and gluten) were added to GR as a latex blend. In general, protein addition reduced bulk viscosity and improved thermo-oxidative stability. The gel content and green strength of the polymer–protein blends were increased, with the exception of gliadin, but not to levels observed for Hevea. Effects on vulcanization and mechanical properties in compounds were surprisingly influenced by the choice of antioxidants used. Our results demonstrate the potential of proteins as bio-based rubber compounding additives.

Physical and mechanical properties of natural rubber modified cement paste

2020 ◽  
Vol 244 ◽  
pp. 118319 ◽  
Author(s):  
Gampanart Sukmak ◽  
Patimapon Sukmak ◽  
Suksun Horpibulsuk ◽  
Teerasak Yaowarat ◽  
Kittipong Kunchariyakun ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Natural Rubber ◽  
Cement Paste ◽  
Physical And Mechanical Properties

Properties of Natural Rubber Nanocomposites Reinforced with Carbon Nanotubes

2015 ◽  
Vol 1109 ◽  
pp. 195-199 ◽  
Author(s):  
Abd Aziz Azira ◽  
Dayang Habibah Abangismawi I. Hassim ◽  
D. Verasamy ◽  
Abu Bakar Suriani ◽  
M. Rusop
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Natural Rubber ◽  
Considerable Increase ◽  
Physical And Mechanical Properties ◽  
Rubber Matrix ◽  
Rubber Composites ◽  
Transmission Electron ◽  
Maximum Conductivity ◽  
Polymer Latex

In order to achieve improvements in the performance of rubber materials, the development of carbon nanotube (CNT)-reinforced rubber composites was attempted. The CNT/epoxidised natural rubber (ENR) nanocomposite was prepared through latex technology. Physical and mechanical properties of the CNT/ENR nanocomposites were characterized in contrast to the carbon black (CB)/ENR composite. The dispersion of the CNTs in the rubber matrix and interfacial bonding between them were rather good; monitored transmission electron microscopy and scanning electron microscopy. The mechanical properties of the CNT-reinforced ENR showed a considerable increase compared to the neat ENR and traditional CB/ENR composite. The storage modulus of the CNT/ENR nanocomposites greatly exceeds that of neat ENR and CB/ENR composites and a maximum conductivity of about 1 S m-1 can be achieved. The approach presented can be adapted to other CNT/polymer latex systems.

Wood anatomical and topochemical analyses to characterize juvenile and adult wood of lesser-known species from Central America (Mexico)

IAWA Journal ◽  
2019 ◽  
Vol 40 (4) ◽  
pp. 785-803 ◽  
Author(s):  
Volker Haag ◽  
Gerald Koch ◽  
Hans-Georg Richter ◽  
Robert Evans ◽  
José Antonio Silva Guzmán ◽  
...  
Keyword(s):  
Central America ◽  
Fibre Length ◽  
Physical And Mechanical Properties ◽  
Wood Properties ◽  
Added Value ◽  
Individual Species ◽  
Image Analysis System ◽  
Acetone Water ◽  
Analysis System ◽  
Tabebuia Rosea

ABSTRACT Anatomical and subcellular characteristics of juvenile and adult wood of seven species (Manilkara zapota (L.) P. Royen, Platymiscium yucatanum Standl., Lonchocarpus castilloi Standl., Roseodendron donnell-smithii (Rose) Miranda, Terminalia buceras (L.) Wright, Tabebuia rosea (Bertol.) DC., Lysiloma latisiliquum (L.) Benth. from Mexico, including a histometric evaluation, were investigated by light microscopy with a digitized image analysis system and by X-ray diffractometry using the SilviScan® system. The topochemical distribution of lignin and phenolic deposits in the tissue was studied by means of cellular UV-microspectrophotometry (UMSP). Extractive contents (acetone/water and water) were determined gravimetrically. The results of the structural and topochemical analyses were compared with the interrelations of certain anatomical and subcellular structures as well as the topochemical composition with regard to the physical and mechanical properties of the timbers investigated. The objective was to provide a detailed cellular and subcellular description of the heartwood of seven lesser-known timbers from Central America. All examined tree species show significant differences between juvenile and adult heartwood. For individual species, however, the differences vary greatly and have to be individually assessed in addition to general trends observed for all studied species. It has been shown that vessel size, fibre length, size of fibre lumina, and height and width of rays, as well as the content of extractives and topochemical composition of the cell walls, are suitable indicators for the differentiation of the two heartwood types. The results also contribute to a better understanding of the wood properties of the investigated timbers in relation to their utilization and added value increase.

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