Moisture Uptake Research Articles

Study of environmental behavior and its effect on solid particle erosion behavior of hierarchical porous activated carbon‐epoxy composite

AbstractPorous carbon materials have versatile physical and chemical characteristics; however, these materials are not be fully exploited as reinforcements in polymer composites. The present investigation focuses on extraction of hierarchical porous carbon and its utilization in polymer composite in order to enhance the erosion wear resistance and hardness of polymer composite. The current research work also demonstrates the wear behavior of the hierarchical porous carbon epoxy composite when exposed to different environmental conditions. The attributes of hierarchical carbon have verified through different characterization techniques, further porous carbon with optimum properties has been included as reinforcement in different ratios viz. 1, 2 and 3 wt. % to make the epoxy composites. The composites were studied for their hardness, moisture absorption and erosion wear behavior at variable impingement angles (30°, 45°, 60°, and 90°) and impingement velocities (101, 119, and 148 m/s). Moisture uptake results suggests that the increase in filler percentage increased the moisture absorption, and the highest moisture absorption was reported in composite immersed in saline water environment. It was observed that addition of activated carbon particles has enhanced hardness and wear resistance of the composite. Composite with 2 wt.% particulate reinforcement was found to be the optimum percentage of reinforcement which was subjected to 82.4% less material loss that is, erosion rate at 45° impact angle compared to neat polymer. From the erosion wear results it was further noticed that moisture absorption has deteriorated the erosion wear resistance of composites resulting in high material loss.

Moisture Sources for Precipitation Associated With Major Hurricanes During 2017 in the North Atlantic Basin

AbstractThe 2017 North Atlantic tropical cyclone season was among the most active in the last two decades, with 17 named storms, of which six reached the major hurricane (MH) intensity: Harvey, Irma, Jose, Lee, Maria, and Ophelia. In this study, the water vapor sources for precipitation for these six MHs were examined using a Lagrangian approach. The particle dispersion model, FLEXPART, was used to identify moisture sources. Overall, the North Atlantic Ocean, the Caribbean Sea, and the Gulf of Mexico were identified as the main moisture sources, supplying ∼75%–85% of the atmospheric humidity gained by tropical cyclones, which resulted in precipitation associated with the MHs. However, the South Atlantic Ocean also contributed considerable humidity (∼14%–20%), and the remaining ∼1%–5% originated from the tropical eastern Pacific Ocean. The accumulated moisture uptake higher than the 90th percentile generally appeared within approximately 3° to 5° of the TC trajectory.

Development of a Transdermal Delivery System for Tacrine

Tacrine has several mechanisms of action. The putative primary mechanism of action of tacrine for Alzheimer's disease is reversible inhibition of acetylcholinesterase (AChE), which thus slows the breakdown of the chemical messenger acetylcholine (ACh) in the brain. Tacrine also inhibits butyrylcholinesterase activity. In accumulation, tacrine blocks sodium and potassium channels. Tacrine also acts as a histamine N-methyltransferase inhibitor. This study was carried out to develop matrix based transdermal patches containing Tacrine to overcome the first pass metabolism and to reduce frequency of dosing compared to oral route. . Matrix type of transdermal patches was developed by using Methocel K4M, Methocel K15M, Methocel K100M and Xanthan gum polymers. Transdermal patches were prepared by employing solvent casting method. Drug excipients compatibility studies were carried out by using FTIR, and it was observed that there were no interactions. Formulations were prepared with the varying concentrations polymers ranging from F1-F16, and all the formulations were evaluated for various physical parameters Physical appearance, Flatness, Weight variation, Thickness, Folding endurance, Drug content, Moisture uptake, Moisture content and Swelling study and all the results were found to be within the pharmacopeial limits, invitro drug release studies by using dialysis membrane. Among all the 16 Tacrine transdermal patches formulations F5 formulations which contain Methocel K15M 100 mg had shown 97.61% % cumulative drug release within 12 hours.

The Effect of High Protein Powder Structure on Hydration, Glass Transition, Water Sorption, and Thermomechanical Properties.

Poor solubility of high protein milk powders can be an issue during the production of nutritional formulations, as well as for end-users. One possible way to improve powder solubility is through the creation of vacuoles and pores in the particle structure using high pressure gas injection during spray drying. The aim of this study was to determine whether changes in particle morphology effect physical properties, such as hydration, water sorption, structural strength, glass transition temperature, and α-relaxation temperatures. Four milk protein concentrate powders (MPC, 80%, w/w, protein) were produced, i.e., regular (R) and agglomerated (A) without nitrogen injection and regular (RN) and agglomerated (AN) with nitrogen injection. Electron microscopy confirmed that nitrogen injection increased powder particles’ sphericity and created fractured structures with pores in both regular and agglomerated systems. Environmental scanning electron microscopy (ESEM) showed that nitrogen injection enhanced the moisture uptake and solubility properties of RN and AN as compared with non-nitrogen-injected powders (R and A). In particular, at the final swelling at over 100% relative humidity (RH), R, A, AN, and RN powders showed an increase in particle size of 25, 20, 40, and 97% respectively. The injection of nitrogen gas (NI) did not influence calorimetric glass transition temperature (Tg), which could be expected as there was no change to the powder composition, however, the agglomeration of powders did effect Tg. Interestingly, the creation of porous powder particles by NI did alter the α-relaxation temperatures (up to ~16 °C difference between R and AN powders at 44% RH) and the structural strength (up to ~11 °C difference between R and AN powders at 44% RH). The results of this study provide an in-depth understanding of the changes in the morphology and physical-mechanical properties of nitrogen gas-injected MPC powders.

Moisture origin, transport pathways, and driving processes of intense wintertime moisture transport into the Arctic

Abstract. A substantial portion of the moisture transport into the Arctic occurs in episodic, high-amplitude events with strong impacts on the Arctic's climate system components such as sea ice. This study focuses on the origin of such moist-air intrusions during winter and examines the moisture sources, moisture transport pathways, and their linkage to the driving large-scale circulation patterns. For that purpose, 597 moist-air intrusions, defined as daily events of intense (exceeding the 90th anomaly percentile) zonal mean moisture transport into the polar cap (≥70∘ N), are identified. Kinematic backward trajectories combined with a Lagrangian moisture source diagnostic are then used to pinpoint the moisture sources and characterize the airstreams accomplishing the transport. The moisture source analyses show that the bulk of the moisture transported into the polar cap during these moist-air intrusions originates in the eastern North Atlantic with an uptake maximum poleward of 50∘ N. Trajectories further reveal an inverse relationship between moisture uptake latitude and the level at which moisture is injected into the polar cap, consistent with ascent of poleward-flowing air in a baroclinic atmosphere. Focusing on intrusions in the North Atlantic (424 intrusions), we find that lower tropospheric moisture transport is predominantly accomplished by two types of airstreams: (i) cold, polar air warmed and moistened by surface fluxes and (ii) air subsiding from the mid-troposphere into the boundary layer. Both airstreams contribute about 36 % each to the total transport. The former accounts for most of the moisture transport during intrusions associated with an anomalously high frequency of cyclones east of Greenland (218 intrusions), whereas the latter is more important in the presence of atmospheric blocking over Scandinavia and the Ural Mountains (145 events). Long-range moisture transport, accounting for 17 % of the total transport, dominates during intrusions with weak forcing by baroclinic weather systems (64 intrusions). Finally, mid-tropospheric moisture transport is invariably associated with (diabatically) ascending air and moisture origin in the central and western North Atlantic, including the Gulf Stream front, accounting for roughly 10 % of the total transport. In summary, our study shows that moist-air intrusions into the polar atmosphere result from a combination of airstreams with predominantly high-latitude or high-altitude origin, whose relative importance is determined by the underlying driving weather systems (i.e., cyclones and blocks).

Bio-composites from spent hen derived lipids grafted on CNC and reinforced with nanoclay

A novel cellulose nanocrystal (CNC)-grafted macromonomer containing both saturated and unsaturated fatty acids was synthesized from spent hen lipids, which was further homopolymerized and copolymerized with styrene and in-situ nano-reinforced into nanocomposites. The aim of this study was to investigate the effect of CNC-grafting and nanoclay as filler at different ratios on the thermal, mechanical and water absorption behavior of the developed composites. The chemical grafting on CNC, its polymerization and effect of nanofiller were characterized and investigated by various analytical techniques. The results revealed improved thermal stability for all nanocomposites with higher onset of degradation temperature and more char production for 5% and 10% nanoclay composites, while increased tensile strength was obtained for all nanoclay composites. However, reduced storage modulus and higher moisture uptake was observed for nanocomposites compared to the control polymer composite, which can be attributed to poor interfacial adhesion between nanofiller and matrices, and hydrophilic nature of nanofillers, respectively.

Quantitative prediction of moisture content distribution in acetylated wood using near-infrared hyperspectral imaging

The uptake of moisture severely affects the properties of wood in service applications. Even local moisture content variations may be critical, but such variations are typically not detected by traditional methods to quantify the moisture content of the wood. In this study, we used near-infrared hyperspectral imaging to predict the moisture distribution on wood surfaces at the macroscale. A broad range of wood moisture contents were generated by controlling the acetylation degree of wood and the relative humidity during sample conditioning. Near-infrared image spectra were then measured from the surfaces of the conditioned wood samples, and a principal component analysis was applied to separate the useful chemical information from the spectral data. Moreover, a partial least squares regression model was developed to predict moisture content on the wood surfaces. The results show that hyperspectral near-infrared image regression can accurately predict the variations in moisture content across wood surfaces. In addition to sample-to-sample variation in moisture content, our results also revealed differences in the moisture content between earlywood and latewood in acetylated wood. This was in line with our recent studies where we found that thin-walled earlywood cells are acetylated faster than the thicker latewood cells, which decreases the moisture uptake during the conditioning. Dynamic vapor sorption isotherms validated the differences in moisture content within earlywood and latewood cells. Overall, our results demonstrate the capabilities of hyperspectral imaging for process analytics in the modern wood industry.Graphical abstract

Salt frost scaling of concrete – new insights regarding the damage mechanism

To achieve the important goal of clinker reduction for concretes in cold and temperate climates, it is important to understand the underlying mechanisms for salt frost scaling. Two conflicting damage theories dominate the current State of the Art – the glue spall theory and the cryogenic suction theory. In this study, important aspects of both theories were evaluated experimentally using salt frost scaling tests on concrete and low temperature differential scanning calorimetry. It was found, that the generation of scaling in a salt frost attack could be better explained by the cryogenic suction theory, which is based on the uptake of highly concentrated brine at sub-zero temperatures. However, this theory cannot account for the pessimal effect of low de-icing salt concentrations in salt frost scaling tests, as it does not consider the moisture uptake during the thawing phase of a freeze-thaw cycle. By expanding the cryogenic suction theory by that aspect, a comprehensive theory for salt frost damage was obtained. In that theory the cryogenic suction of highly concentrated brine during frost is responsible for the generation of scaling. The moisture uptake during the thawing phase balances the de-icing salt concentration in the concrete and accounts for the pessimum effect.

Characterization of morphological changes to an epoxy-based polymer used as a corrosion-preventative lining in retorted canned tomatoes

This study investigated how heat-induced changes to compounds in tomatoes initiated morphological changes to the lining in metal cans. X-ray diffraction, Fourier transform near-infrared spectroscopy, and scanning electron microscopy characterized these morphological changes and we investigated the elemental composition of the lining in the cans before and after heat processing. All tomato-filled cans were sealed, retorted (121 °C, 30 min), then stored at 49 °C for 50 days. Selected-ion flow-tube mass spectrometry then measured the concentrations of volatile compounds in the polymeric linings of unprocessed and processed cans. Results showed that thermal degradation of amino acids in the tomatoes gave rise to volatile methyl sulfides that were subsequently sorbed by the can linings. This process caused breaches in the lining, moisture uptake by the polymer, delamination, and exposure of the base-metal in the cans. These effects allowed electrolytes in the tomatoes to initiate corrosion in the wall of the cans. • This study investigated heat induced changes to metal cans caused by packaged tomatoes. • Diced Roma tomatoes were retorted in metal cans coated with a BPA-NI polymer. • Heat induced changes to the protective coating of the tomato filled cans occurred. • Results showed that volatile methyl sulfides were sorbed by the coating of the cans. • This caused coating delamination, moisture uptake and corrosion in the cans.

Preparation and characterization of biocomposite film derived from microcrystalline cellulose (MCC) of jackfruit rind waste

Biocomposite cornstarch films with various microcrystalline cellulose (MCC) derived from jack fruit rind (JR) had prepared via the solution casting method. This study aimed to investigate the effects of jackfruit rind microcrystalline cellulose (JR-MCC) composition on the properties of cornstarch biocomposite films. The FTIR analysis demonstrated that the addition of JR-MCC did not significantly change the chemical structure of the obtained composites. The mechanical test revealed that the tensile strength and Young’s Modulus decreased with increasing JR-MCC content while the value of elongation at break increased. As JR-MCC content increased from 2.5% to 15%, the water solubility decreased significantly from 21.80% to 12.73%. This phenomenon happened because JR-MCC reduced the water solubility of cornstarch-based films. JR-MCC was firm to dissolve in water and needed a longer time to dissolve. The moisture uptake and biodegradability of the films reinforced with JR-MCC also increased due to the sensitivity towards moisture.

Cassava starch film loaded with extract of Piper betel leaf for anti-inflammatory activity

The aim of the present research work was to formulate a transdermal film of Piper betel L. leaf extract along with diclofenac sodium and evaluate its anti-inflammatory activity. The ethanolic extract of P. betel leaf was obtained by solvent extraction method using a Soxhlet apparatus. The P. betel leaf extract was analysed for inhibition of the albumin denaturation and it showed a significant inhibition of the albumin denaturation. The topical film was then prepared by solvent casting method using diclofenac sodium and P. betel leaf extract. The film was evaluated for drug content, thickness, weight uniformity, folding endurance, moisture content, moisture uptake, and barrier properties of the film. The formulated film was thin, flexible, and possessed satisfactory physicochemical properties. The anti-inflammatory potential of the film was evaluated by using carrageenan-induced rat paw oedema method on albino Wistar rats. The anti-inflammatory activity of film was found comparable with standard diclofenac sodium film and exhibited inhibition of oedema within 4 h. This signifies that the combination of P. betel leaf extract and diclofenac sodium has remarkable potential to serve as synergistic topical anti-inflammatory film preparation than simple topical film formulation of diclofenac sodium.

Aspirin-hydrogel ocular film for topical delivery and ophthalmic anti-inflammation

Ocular drug delivery in hydrogel forming film form has several benefits over conventional dosage forms. An ophthalmic anti-inflammation study was undertaken using topically applied aspirin in a hydrogel film formulation. A hydroxypropyl methylcellulose (HPMC) matrix film formulation was prepared by the solvent casting and evaporation technique by taking triethanolamine (TEA) as a plasticizer. Ex vivo corneal permeation as well as anti-inflammatory potential of aspirin was studied on carrageenan induced rabbit eye model. Moisture uptake was found to be in the range of 17.1 and 19.1 % for all the film formulations. The film with the higher HPMC content exhibited both increased moisture uptake and amount of swelling. Among the formulations, the swelling order was found to increase with increasing amount of HPMC in the film. Presence of the hydrogel matrix forming polymer sustained the drug release and corneal permeation for more than 6 h and controlled the process by the diffusion mechanism. The signs of carrageenan induced acute inflammation was inhibited completely within just 2 h of placing the film in the rabbit eye whilst the positive control continued showing redness and increased tear secretion. Aspirin ocular film formulation could be utilized for ocular anti-inflammation for an extended period of time with better patient compliance.

Metal organic framework/polyelectrolyte composites for water vapor sorption applications.

Metal-organic framework (MOF) core particles of MIL-101(Cr), aluminum fumarate (Basolite® A520), MIL-53-TDC, zirconium fumarate, and UiO-66 were modified by adsorption of thin polyelectrolyte (PE)-based shells without deterioration of their crystal structure. By applying different PEs and depositing a single layer (MOF/PE) or one to three layer-by-layer assembled bilayers (MOF/LbL), the mass percent of shell material in the composite was varied from 0.6-2.5% to 50%. Under a constant relative pressure of water vapor, the moisture uptake by a MOF/PE and a MOF/LbL is rather comparable with its S-shaped curvature to that of pristine MOFs. The relevant differences, such as a shift of the ascending adsorption part to lower/higher relative pressure or an increase/decrease in water uptake in selected regions, are associated with the core-shell structure and related to the morphological changes of the MOF powders. The hydrophilic surface promotes the formation of liquid menisci at the points of contact between particles and accelerates the moisture uptake and loss. A decrease in water sorption under an atmosphere with high humidity by some composites can be associated with the inhibition of liquid water condensation by the more hydrophobic shells.

Development and optimization of metoclopramide containing polymeric patches: impact of permeation enhancers

The study is aimed to develop a monolithic controlled matrix transdermal patches containing Metoclopramide as a model drug by solvent casting method. Eudragit L100, Polyvinylpyrrolidone K-30, and Methylcellulose were used in different ratios and Polyethylene glycol 400 added as a plasticizer. Resulting patches were evaluated for their physicochemical characters like organoleptic characters, weight variation, folding endurance, thickness, swelling index, flatness, drug content, swelling index, percentage erosion, moisture content, water vapor transmission rate and moisture uptake. Formed patches were also evaluated through Fourier transform spectroscopy (FT-IR), X-ray diffraction (XRD), Differential Scanning calorimetry (DSC) and Scanning Electron Microscopy (SEM). Results of SEM unveiled smooth surface of drug-loaded patches. In-vitro dissolution studies were conducted by using dissolution medium phosphate buffer saline pH 7.4. Effect of natural permeation enhancers was elucidated on two optimized formulations (Z4 and Z9). Different concentrations (5%-10 %) of permeation enhancers i.e. Olive oil, Castor oil and Eucalyptus oil were evaluated on Franz diffusion cell using excised abdominal rat skin. Z4-O2 (Olive oil 10%) had enhanced sustain effect and flux value (310.72) close to the desired flux value. Z4-O2 followed Higuchi release model (R2= 0.9833) with non-fickian diffusion release mechanism (n=0.612).

Commercial wound dressings for the treatment of exuding wounds: an in-depth physico-chemical comparative study

BackgroundNowadays, a wide range of wound dressings is already commercially available. The selection of the dressing is of paramount importance as inappropriate wound management and dressing selection can delay the wound healing process. Not only can this be distressing for the patient, but it can also contribute to complications such as maceration and subsequent infection. Many researchers are targeting the design of dressings with superior properties over existing commercial dressings. However, reported results in the state-of-the-art are rarely benchmarked against commercial dressings. The aim of this study was to determine several characteristics of a large variety of the most frequently used commercial wound dressings, providing an overview for both practitioners and researchers.MethodsFor this comparative study, 11 frequently used commercial wound dressings were selected, representing the different types. The morphology was studied using scanning electron microscopy. The dressings were characterized in terms of swelling capacity (water, phosphate buffered saline and simulated wound fluid), moisture vapour transmission rate (MVTR) and moisture uptake capacity (via dynamic vapour sorption) as well as mechanical properties using tensile testing and texturometry.ResultsThe selected dressings showed distinctive morphological differences (fibrous, porous and/or gel) which was reflected in the different properties. Indeed, the swelling capacities ranged between 1.5 and 23.2 g/g (water), 2.1 and 17.6 g/g (phosphate buffered saline) or 2.9 and 20.8 g/g (simulated wound fluid). The swelling capacity of the dressings in water increased even further upon freeze-drying, due to the formation of pores. The MVTR values varied between 40 and 930 g/m2/24 h. The maximal moisture uptake capacity varied between 5.8% and 105.7% at 95% relative humidity. Some commercial dressings exhibited a superior mechanical strength, due to either being hydrophobic or multi-layered.ConclusionsThe present work not only offers insight into a valuable toolbox of suitable wound dressing characterization techniques, but also provides an extensive landscaping of commercial dressings along with their physico-chemical properties, obtained through reproducible experimental protocols. Furthermore, it ensures appropriate benchmark values for commercial dressings in all forthcoming studies and could aid researchers with the development of novel modern wound dressings. The tested dressings either exhibited a high strength or a high swelling capacity, suggesting that there is still a strong potential in the wound dressings market for dressings that possess both.

Interlaminar Shear, Bending, and Water Retention Behavior of Nano-SiO2 Filler-Incorporated Dharbai/Glass Fiber-Based Hybrid Composites under Cryogenic Environment

In current history, adding nanoscale and micron-sized filler materials to composite materials for fabrication has been a popular approach for improving the composite’s mechanical characteristics. Due to their lower friction coefficient, excellent mechanical strength modulus, and low moisture uptake, filler-based hybrid composite materials are replacing metallic materials. Glass/Dharbai hybrid composites with nano-SiO2 fillers have been created in this study. After manufacture, the composite materials were treated with liquid nitrogen at 177 K for various durations. Every sample material was cut according to ASTM standards to investigate mechanical features such as ILSS, impact test, and flexural strength. The broken composite specimen was studied using a scanning electron microscope. Water retention studies have been conducted under two distinct liquid solutions: tab or regular water and seawater. ILSS, flexural strength, and water retention were all greater in 4 wt.% of nanofiller-rich composites than in ordinary composites. Compared to 30 minutes, the 15-minute cryo-treated specimens provide the highest mechanical strength. On the other hand, the automobile, aviation, and shipbuilding sectors would benefit from a nanofiller-based composite.

Water Retention Behaviour and Fracture Toughness of Coir/Pineapple Leaf Fibre with Addition of Al2O3 Hybrid Composites under Ambient Conditions

Due to their high mechanical and physical properties, natural fibre-based composite materials have been important in many fields of application for four to five years. The chief intention of the current study is to determine the mechanical and water retention features of composite materials under ambient conditions. Coir and pineapple leaf fibre were used as a reinforcement, aluminium oxide as additives, and polyester as a matrix. The hybrid resources were laminated by the manual hand lay-up method. The mechanical characteristics like tensile, flexural, and fracture toughness properties were tested as per the ASTM standard. Nanoparticle weight ratio and its size variation significantly impact mechanical qualities. The hybrid composite’s water retention behaviour was tested for two types of water levels: ordinary tab water and nanofluid. The moisture uptake of the composites rose as the fibre volume increased, and after 640 hours, all of the composites had reached equilibrium. According to the results, the following combinations have the maximum mechanical strength: 15% wt.% coir, 15% wt.% pineapple, 10% wt.% nanofiller, and 60% wt.% polyester resin. The combinations mentioned above withstand the most load during the tests. Compared to 20% filler, 10% Al2O3 filler produces good interfacial adhesion in the current study. The fractured specimens were analyzed using scanning electron microscopic (SEM) pictures to recognize better the failure process of composites during mechanical testing.

Water barrier properties of carboxymethyl cellulose/halloysite nanotubes nanocomposite to be used in food packaging applications

In this research, novel carboxymethyl cellulose (CMC) based nanocomposite film containing 5%wt of halloysite nanotubes (HNT) was fabricated via solvent casting method as a potential biodegradable packaging material. The performances of the nanocomposite packaging material was investigated by assessing the moisture content, moisture uptake, water solubility, water vapor barrier properties and opacity. The incorporation of 5%wt HNT into the film remarkably reduced the moisture uptake by ∼ 28.01% at 97% RH and 31.08% at 40% RH. Water permeability value of CMC/HNT film showed as 7.08 ± 0.26 × 10−11 gm/m2Pas at freezing, 3.37 ± 0.33 × 10−11 gm/m2Pas at refrigeration and 1.14 ± 0.00 × 10−11 gm/m2Pas at ambient environmental conditions respectively. Subsequent to the thermal annealing process, the water vapor permeation ability was drastically declined in the HNT added nanocomposite films at all three different conditions (freezing, refrigeration and ambient) due to enhancing the crystalline structure. Furthermore, the addition of nanofillers into the polymer matrix significantly induced the UV blocking property of the film. These findings disclosed that prepared CMC/5%HNT nanocomposite films can be a potential food packaging material.Keywords: barrier properties, carboxy methyl cellulose, halloysite nanotubes

Pyrolysis of pellets prepared from pure and blended biomass feedstocks: Characterization and analysis of pellets quality

Recently, pyrolysis integrated with pelletization has received great attention. In the current study, various physical, mechanical, chemical and thermal characteristics of furfural residue pellets (FRPs), sewage sludge pellets (SSPs), furfural residue-sewage sludge pellets (FRSSPs) were studied at different pyrolysis temperature (200–850 °C) and residence time (15–45 min). The mass and energy yields of pellets dropped drastically with increasing pyrolysis temperature. Higher heating values (HHV) of pyrolysed furfural residue pellets (PYFRPs) and furfural residue-sewage sludge pellets (PYFRSSPs) increased from 22.22 to 26.76 MJ/kg, and 20.59–23.72 MJ/kg, respectively with increasing temperature from 200 to 850 °C. However, the HHV of pyrolysed sewage sludge pellets (PYSSPs) decreased with increasing temperature. The lowest pellet density and strength were found at 850 °C and residence time of 45 min. The pellets remained dimensionally stable during the water immersion test and after a storage time of 2 weeks, the relaxed densities and strength remained unchanged. The volumetric energy density of PYFRPs (30.35 kJ/m3) was found to be higher than PYSSPs (8.92 kJ/m3) and PYFRSSPs (23.85 kJ/m3) at the same process conditions. Thermal treatment enhanced the hydrophobicity of pellets. The lowest moisture uptake of 1.14 wt%, 1.8 wt%, and 1.58 wt% for the corresponding PYFRPs, PYSSPs and PYFRSSPs were observed at pyrolysis temperature of 300 °C. The maximum methylene blue and iodine adsorption values (i.e. 96 and 244.8 mg/g), (191 and 314.7 mg/g) and (121.6 and 263 mg/g) for PYFRPs, PYSSPs and PYFRSSPs were found, respectively, at temperature of ≥ 450 °C. Pyrolysis at higher temperature significantly reduced the heavy metals in PYFRSSPs and PYSSPs.

Characterization and Properties of Biodegradable Thermoplastic Arrowroot Starch Crosslinked by Glutaraldehyde Processed by Compression Molding Technique

Although starch is available and biodegradable, hydrophilicity and mechanical properties are still main disadvantages for many applications. In this study, arrowroot starch, a perennial herb found in tropical climates and extracted from the tubers of the arrowroot plant was used. The arrowroot starch was chemically modified by crosslinking with different amounts of glutaraldehyde in order to overcome the starch disadvantages. The crosslinked starch was then prepared as thermoplastic starch by plasticizing with glycerol, compounding in an internal mixer and finally shaping in a compression molding machine. An increase of gel fraction and decrease of swelling as well as the moisture uptake of different thermoplastic crosslinked arrowroot starch samples were observed, all of which indicated a crosslinking reaction of glutaraldehyde with the starch molecules. The thermal degradation temperature of thermoplastic crosslinked arrowroot starch, determined from thermogravimetric analysis technique, increased when compared with thermoplastic arrowroot starch. The extensibility of the thermoplastic crosslinked arrowroot starch also improved via glutaraldehyde crosslinking. Higher content of glutaraldehyde also caused lower swelling and moisture uptake including higher gel fraction and extensibility. Moreover, crystallinity, morphology and biodegradability were also examined.