Glycerol Concentration Research Articles

Synergistic interaction on quasi-binary mixture of amino sulfonate amphoteric surfactant with nonionic diethanolamide induced by glycerol and its concentration

Molecular interaction about a quasi-binary mixtures of an amino sulfonate surfactant, sodium 3-(N-dodecyl ethylenediamino)-2-hydroxypropyl sulfonate (DES), with a fatty acid diethanolamide derived from coconut oil (CDA) in aqueous solutions containing both the glycerol of 0.100 mol/L and 0.200 mol/L was investigated using the surface tension measurement. The interfacial parameters indicate that the mixing of DES with CDA can promote the formation of the more compact distribution of molecules adsorbed in the mixed monolayer, the mixing ratio of the mixture induces the difference in the adsorption behaviors at air–liquid interface, and the standard free energy of adsorption at air–liquid interface implies the benefit of adsorption and the change of adsorption behavior based on both the concentration of glycerol in solutions and the mixing ratio in the mixture. In the framework of pseudo-phase separation model, thermodynamic models including the Clint’s model, the Rubingh’s model and the Maeda’s model were employed to effectively estimate the related micellization and thermodynamic parameters. The nonideal mixing of DES with CDA and their synergistic interactions in the mixed micelle depend on both the mixing ratio of the mixture and the concentration of glycerol in solutions. The abundant amount of DES in mixed micelle will result in the absence of synergistic interaction in aqueous solutions containing the glycerol of 0.100 mol/L, and whereas the abnormal case does not again emerge on increasing the concentration of glycerol to 0.200 mol/L. The compatibility in molecular conformation, the steric hindrance, the electrostatic repulsion and the hydrogen-bond formation are adopted to theoretically explain the interaction behavior. Thermodynamic parameters obtained using the Maeda’s treatments also confirm the absence or the presence of synergistic interaction and the formation of stable mixed micelle. These findings will help with understanding the intermolecular behavior and the effect of alcohol concentration.

Development of Biodegradable Thermosetting Plastic Using Dialdehyde Pineapple Stem Starch.

Starch extracted from pineapple stem waste underwent an environmentally friendly modification process characterized by low-energy consumption. This process resulted in the creation of dialdehyde pineapple stem starch featuring varying aldehyde contents ranging from 10% to 90%. Leveraging these dialdehyde starches, thermosetting plastics were meticulously developed by incorporating glycerol as a plasticizer. Concurrently, unmodified pineapple stem starch was employed as a control to produce thermoplastic material under identical conditions. The objective of streamlining the processing steps was pursued by adopting a direct hot compression molding technique. This enabled the transformation of starch powders into plastic sheets without the need for water-based gelatinization. Consequently, the dialdehyde starch-based thermosetting plastics exhibited exceptional mechanical properties, boasting a modulus within the range of 1862 MPa to 2000 MPa and a strength of 15 MPa to 42 MPa. Notably, their stretchability remained relatively modest, spanning from 0.8% to 2.4%. Comparatively, these properties significantly outperformed the thermoplastic counterpart derived from unmodified starch. Tailoring the mechanical performance of the thermosetting plastics was achieved by manipulating the glycerol content, ranging from 30% to 50%. Phase morphologies of the thermoset starch unveiled a uniformly distributed microstructure without any observable starch particles. This stood in contrast to the heterogeneous structure exhibited by the thermoplastic derived from unmodified starch. X-ray diffraction patterns indicated the absence of a crystalline structure within the thermosets, likely attributed to the establishment of a crosslinked structure. The resultant network formation in the thermosets directly correlated with enhanced water resistance. Remarkably, the thermosetting starch originating from pineapple stem starch demonstrated continued biodegradability following a soil burial test, albeit at a notably slower rate when compared to its thermoplastic counterpart. These findings hold the potential to pave the way for the utilization of starch-based products, thereby replacing non-biodegradable petroleum-based materials and contributing to the creation of more enduring and sustainable commodities.

Saccharomyces cerevisiae vs Escherichia coli in the valorization of crude glycerol to produce ethanol

The transformation of crude glycerol into ethanol at a lab scale through Saccharomyces cerevisiae and Escherichia coli was evaluated. The fermentation using three concentrations (10, 20, and 30 g L−1) of crude glycerol was evaluated in 250 mL reactors; the growth of the microorganisms was also evaluated considering pure glycerol. Afterward, the microorganism showing the best performance fermenting crude glycerol was evaluated in a 7 L reactor. Both microorganisms could grow in pure and crude glycerol; the ethanol production with E. coli ranged from 0.17 to 0.45 g L−1 and from 0.49 to 0.60 g L−1 with S. cerevisiae in micro-reactors. In the 7 L reactor, S. cerevisiae could still grow, and a maximum ethanol production of 0.73 g L−1 was obtained. It is concluded that even if the yield production is low and more profound studies are required, S. cerevisiae could be used to revalorize crude glycerol.

Is glycerol a good cryoprotectant for sperm cells? New exploration of its toxicity using avian model

Glycerol is a cryoprotectant used widely for the cryopreservation of animal sperm, but it is linked to a decrease in fertility. The mechanism underlying the negative effects of glycerol remains unclear. Therefore, in this study, we aimed to gain a better understanding by using the chicken model. First, we investigated the impact of increasing the concentration of glycerol during insemination on hen fertility. Our findings revealed that 2% glycerol resulted in partial infertility, while 6% glycerol led to complete infertility. Subsequently, we examined the ability of sperm to colonize sperm storage tubules (SST) during in vivo insemination and in vitro incubation. The sperm used in the experiment were stained with Hoechst and contained 0, 2, or 6% glycerol. Furthermore, we conducted perivitelline membrane lysis tests and investigated sperm motility, mitochondrial function, ATP concentration, membrane integrity, and apoptosis after 60 min of incubation with different glycerol concentrations (0%, 1%, 2%, 6%, and 11%) at two temperatures to simulate pre-freezing (4 °C) and post-insemination (41 °C) conditions. Whereas 2% glycerol significantly reduced 50% of sperm containing SST, 6% glycerol completely inhibited SST colonization in vivo. On the other hand, in vitro incubation of sperm with SST revealed no effect of 2% glycerol, and 6% glycerol showed only a 17% reduction in sperm-filled SST. Moreover, glycerol reduced sperm-egg penetration rates and also affected sperm motility, bioenergetic metabolism, and cell death at 4 °C. These effects were observed when the concentration of glycerol exceeded 6%. Furthermore, at 41 °C, glycerol caused even greater damage, particularly in terms of reducing sperm motility. These data altogether reveal important effects of glycerol on sperm biology, sperm migration, SST colonization, and oocyte penetration. This suggests that glycerol plays a role in reducing fertility and presents opportunities for improving sperm cryopreservation.

Optimization of the extraction of phenolic compounds from the leaves of yerba mate (Ilex paraguariensis) through high hydrostatic pressure system using mixture design with process variables.

In this study, a mixture design with process variables was used to optimize the extraction of total phenolic compounds (TPC) from yerba mate leaves through high hydrostatic pressure extraction. The studied variables were pressure (50, 100, and 150 MPa), extraction time (10, 20, and 30 min), and solvent (water, glycerin, and 50% v/v water/50% v/v glycerin). The multiple linear regression model presented an excellent fit (R2 adjusted of 0.9792) and demonstrated the major influence of glycerin content on the water/glycerin mixture solvent for TPC extraction. Optimal process conditions obtained were 69% v/v water, 31% v/v glycerin, 50 MPa pressure, and 10 mintime. PRACTICAL APPLICATION: The paper describes a novel extraction method to obtain phenolic compounds from yerba mate (compounds that can replace synthesized antioxidants in the food industry) using high hydrostatic pressure and environmentally friendly solvents. The extraction process was studied to optimize its performance, obtaining more phenolic compounds from the same amount of yerbamate.

Effects of glycerol content on structure and molecular motion in thermoplastic starch-based nanocomposites during long storage

Thermoplastic starch-based nanocomposites with varying glycerol content and montmorillonite as a nanofiller were studied using dynamic-mechanical analysis (DMA), X-ray diffraction (XRD) and nuclear magnetic resonance (NMR) during one-year storage. DMA results showed that starch-rich and glycerol-rich domains were present in the samples and during storage for up to one year the content of the amorphous phase decreased and molecular mobility changed. 13C NMR and XRD measurements confirmed that ordered structures were formed during storage and its content was larger for samples with higher glycerol content and increased with the storage time. The data obtained from deconvolutions of 1H broad line NMR spectra indicate increased overall molecular mobility in the samples up to four months of storage, while after nine months the trends were opposite. Lower free water content compared to the total water content in the samples determined according to deconvoluted 1H MAS (magic-angle spinning) NMR spectra indicated that a part of water molecules was immobilized in the ordered structures.

Sugar Alcohol Sweetener Production by Yarrowia lipolytica Grown in Media Containing Glycerol.

Most of the world's annual production of mannitol is by chemical means, but, due to increasing demand for natural sweeteners, alternative production methods are being sought. The aim of the study was to screen Yarrowia lipolytica yeast strains and select culture conditions for the efficient and selective biosynthesis of mannitol from glycerol. From 21 strains examined in the shake-flask culture for mannitol biosynthesis from glycerol (100 g/L), three strains were selected-S2, S3, and S4-and further evaluated in batch bioreactor cultures with technical and raw glycerol (150 g/L). The best production parameters were observed for strain S3, which additionally was found to be the most resistant to NaCl concentration. Next, strain S3 was examined in batch culture with regard to the initial glycerol concentration (from 50 to 250 g/L). It was found that the substrate concentrations of 50 and 75 g/L resulted in the highest mannitol selectivity, about 70%. The fed-batch culture system proposed in this paper (performed in two variants in which glycerol was dosed in four portions of about 50 or 75 g/L) resulted in increased mannitol production, up to 78.5 g/L.

Techno-commercial viability of glycerol valorization to 1,2- and 1,3-propanediol using pinch technology

Glycerol is a low-value by-product in biodiesel industries and an important platform chemical in biorefinery with vast derivative potentials. 1,2- and 1,3-Propanediol (PDO) are vital polymer precursors. Valorizing glycerol to PDOs is thus a promising approach for producing renewable chemicals and improving the economics of biodiesel industries. Therefore, this work demonstrated the techno-economic feasibility of PDOs for 100–2000 metric tons per day glycerol feed rate. 1,2-PDO was produced by selective hydrogenolysis of glycerol, while microbial batch and fed-batch fermentation of glycerol was considered for manufacturing 1,3-PDO with the co-production of 2,3-butanediol and ethanol. Pinch analysis was applied for process integration that reduced utility demands by around 19% for 1,2-PDO and 12–16% for 1,3-PDO. However, utilities were still major operating costs in these processes. Besides, utility consumptions and capital expenditures were considerably higher for 1,3-PDO by batch fermentation than 1,2-PDO due to low glycerol concentration (50 g/L). 1,3-PDO production cost (USD 3.42/kg) by batch fermentation was thus much more than 1,2-PDO (USD 0.98/kg). The minimum unitary selling price was USD 1.15 for 1,2-PDO and USD 4.90 for 1,3-PDO (batch) for 8.5% rate of return and five years payback period. However, the microbial 1,3-PDO produced by fed-batch fermentation was economically viable, with USD 0.78 and USD 1.02 as unitary production costs and minimum selling price.

Perspectives on the green hybrid blend of diethanolamine-glycerol for post-combustion carbon dioxide capture via a Y-type micro-reactor

CO2 capture by aqueous primary and secondary alkanolamine solutions is a recognized technology in industrial CO2 separation processes. Yet, certain obstacles caused by high-energy consumption due to the amine regeneration demands, and the formation of thermally stable salts require to be overcome for the development of these solvents. In this paper, glycerol, as a beneficial by-product of biodiesel production, has been introduced as a second promising CO2 absorbent for aqueous diethanolamine solution in a Y-type micro-reactor with dimensions of 800 µm × 4 cm × 19 cm. The experiments of CO2 capture into the hybrid blend of DEA-Glycerol were investigated at ambient pressure and the operating temperature of 25–45 °C, volumetric gas flow rate of 100–300 ml/min, DEA concentrations of 1.5–2.5 M, and glycerol concentrations of 5–15%wt. Experimental results demonstrated that adding 10 wt% glycerol in the aqueous blend of 2.5 M DEA-Glycerol boosts the CO2 removal percentage, RP, up to 96.89%, and enhances the volumetric overall gas-phase mass transfer coefficient, KGaV, and volumetric mass transfer flux, NAaV, to 34.89 kmol/m3.h.kPa and 88.04 kmol/h.m3, respectively. Furthermore, based on the Box-Behnken statistical responses, under the constant concentration of 2 M of DEA, increasing the presence of glycerol from 5 to 10 wt% in the hybrid blend of DEA-Gly can intensify the CO2 RP, KGaV, and NAaV values by 2.12% and 8.66%, and 1.80%, respectively, illustrating the glycerol contribution on the CO2 capture process.

A terpyridyl functionalized rhodamine dye for viscosity sensing with fluorescence enhancement and mitochondria-targeting imaging

Exploring new fluorescent organic dyes with mitochondria-targeted and viscosity-sensitive functions attracts extensive attention because they may provide access to a better understanding of the microenvironments of the subcellular level via biological imaging. Herein a terpyridyl functionalized rhodamine dye (TRMe) has been facilely designed and prepared, which shows a highly selective fluorescence enhancement response to viscosity (1.0–1238.0 cp) in water-glycerol mixtures with the increased glycerol content. In addition, TRMe can respond to viscosity enhancement over a wide pH range (1.0–10.0) and presents low cell toxicity. Besides, a good linearity between the viscosity and fluorescence lifetime of TRMe can be observed. Significantly, TRMe shows excellent mitochondria-targeted performance with a Pearson's colocalization coefficient of 0.958 and can be employed as a tracer for viscosity imaging in Nystatin-stimulated living HeLa cells.

The effect of aloe vera edible coating with carrageenan and glycerol on red chili (Capsicum annum L.) quality during storage

Red chili (Capsicum annum L.) is one of horticultural commodities that rapidly damage due to has high water content, which is around 80-90%. High respiration rate can cause deterioration quickly and shorten shelf life at room temperature stored. In order to prolong shelf life of red chili pepper, aloe vera alone, aloe vera mixed with carrageenan and glycerol can be applied as edible coating. The aims of this study were to evaluate the effect of aloe vera coating, aloe vera mixed with carrageenan and glycerol on red chili pepper. Four treatments with three times repetitions were used and analyzed their effect on weight, total soluble solid, hardness and color changes on red chili pepper. The treatments were aloe vera coating alone, aloe vera mixed with 2% of carrageenan mingled with the different concentration of glycerol, 0.5%, 1% and 1.5%, respectively. Red chilli pepper without any coating were considered as control. All the treated and control red chilli pepper were stored for 15 days at law (10°C) and room temperature (30°C). The data obtained were calculated statistically using analysis of variance (ANOVA). The results showed that edible coating with carrageenan and glycerol stored at low and room temperature had a significant effect reduced in weight loss and coating weight loss of red chili pepper. However, soluble solids concentration, color, were not significantly affected by aloe vera coating with carrageenan and glycerol. The highest quality of red chilli pepper is detected with aloe vera coating mixed with carrageenan and glycerol with 2% and 0.5% concentrations, respectively.

A Discursive Review of Recent Development and Patents on Glycerosomes.

To achieve a target-based drug delivery with minimal side effects, novel drug delivery systems are being continuously explored. Vesicular systems are one such system that can ameliorate the bioavailability of the encapsulated drug by delivering the drug at the targeted site and can minimize the side effect. The objective of this patent review is to provide a vivid description of glycerosomes and their applications. Glycerosomes are sphere-shaped versatile vesicles consisting of one or more phospholipid bilayers similar to liposomes but contain a high concentration of glycerol, which modifies the liposome bilayer fluidity. Glycerosomes can encapsulate both hydrophobic and hydrophilic drugs, which makes them the promising vehicle in the field of drug delivery. Most of the glycerosome formulations prepared were targeted for topical delivery and in particular, a cutaneous route where they have shown promising results. These vesicles are biocompatible and due to the high glycerol concentration, they have improved spreadability and penetrability. It is therefore imperative to explore the other topical routes such as ocular, vaginal, nasal, and rectal for delivery of drugs.

Novel composites of nano-metal–organic frameworks (IRMOF-3) and silver nanoparticles for the ultra-sensitive performance of SERS sensing and optical fiber modes

Rapid chemical detection of drugs of abuse in biological fluids such as blood and saliva is a concern within medicine and law enforcement. As an outcome, a label-free detection platform takes biological fluid samples with concentrations ranging from extremely high to very low. We obtained experimentally the limit of detection (LOD) of glycerol concentration, corresponding to a minimum resolvable refractive index of 3.4 × 10−7 RIU (refractive index unit). We applied the microfluidic device sensors to the quantitating concentration dopamine solutions. The experiment was recorded in real-time as the concentration of analyte injected exposed to the fiber core surface resulted in a sensitive change in optical power transmission. The presented sensors also exhibited reasonably good reproducibility and higher sensitivity, providing the LOD as 1.02 × 10−11 M. A relatively simple scheme procedure is proposed for the simultaneous detection and quantitative assessment of rhodamine B using surface-enhanced Raman spectroscopy with a limit of detection of 10−12 M and a relative standard deviation of 5.78% across a detection concentration range mainly from 10−5 M to 10−12 M. The obtained results demonstrate the potential of nano-metal–organic framework materials as large-area, label-free optical fiber sensors and SERS-based platforms for biomedical sensing and environmental applications.

Improved thermal and mechanical properties of water-blown rigid polyurethane foams synthesized with renewable castor oil and toluene diisocyanate-based trifunctional polyols

In this work, glycerol was chemically modified into novel toluene diisocyanate (TDI) based trifunctional polyol (NTP) by a two step process, involving the reaction of TDI with glycerol to form an isocyanate-terminated pre-polymer, followed by the reaction with glycol. A thermal and mechanical property of water-blown rigid polyurethane foam (WB-PUF) was enhanced by the partial substitution (30 & 50 wt%) of castor oil with glycerol or synthesized NTP. The effects of glycerol content and NTP on the WB-PUF properties were investigated using various characterization techniques including ATR-FTIR, TGA, SEM, compression test, and Shore-A hardness test. Notably, the introduction of NTP substitution into the formulation of WB-PUF foams had beneficial impact on the structure of materials enhancing foam density from 77 kg/m3 to 117 kg/m3 and also exhibited superior thermal and mechanical properties compared to those with glycerol and unmodified foams. Shore A hardness and compression strength of those foams ranged from 50 to 69.5 °Sh A and 1.88-3.28 MPa, respectively. These findings suggest potential applications of the modified WB-PUF in areas such as rigid tissue engineering.

Metabolic profile of goats fed diets containing crude glycerin from biodiesel production.

Feedlot finishing of goats is a growing practice, but the economic viability of this technology is compromised by the inclusion of ingredients such as corn and soybean. An alternative to minimize this barrier is the use of agroindustry coproducts as substitutes for those ingredients, such as crude glycerol. This study aimed to evaluated the metabolism of crossbred Boer finishing goats fed diets containing crude glycerin from biodiesel production. Thirty-two crossbred, castrated goat of age were distributed in a fully randomized experimental design with four treatments and eight replicates. The experiment lasted 69 days, and goats were fed sorghum silage and concentrate, with the inclusion of crude glycerin in the diet at levels of 0, 50, 100, and 150 g/kg on a dry matter basis. The diets did not have an effect (p > 0.05) on the serum urea levels. Increasing dietary crude glycerin levels did not the influence the metabolic or urinary profiles (p > 0.05). The liver tissue of the goats fed diets containing the highest crude glycerin inclusion levels showed deleterious effects. The inclusion of crude glycerin with approximately 6.6 g/kg methanol caused deleterious effects to the liver tissue of Boer crossbred goats as the glycerin concentrations increased. However, glycerin levels did not cause deleterious effects on the liver tissue or on the serum or urinary profiles. The use of crude glycerin with lower methanol content is recommended for goat diets.

Influence of general anaesthesia on circulating biomarkers of glucose metabolism in pigs.

Pigs are widely used in metabolic research with procedures often requiring general anaesthesia. The aim was to investigate the effect of four different anaesthetic protocols: 1) isoflurane inhalation, 2) propofol infusion, 3) a mixture of tiletamine, zolazepam, medetomidine, ketamine and butorphanol (TZMKB)) and 4) ketamine combined with midazolam and xylazine (KMX)) on selected biomarkers during basal and glucose stimulated conditions. Eight domestic pigs were included in a cross-over design. Plasma concentrations of glucose, insulin, C-peptide, glucagon, cortisol, triglycerides, total cholesterol, aspartate amino transferase and alanine amino transferase, creatinine, urea, fructosamine, albumin, free fatty acids (FFAs) and glycerol were measured at baseline, during 2 h of anaesthesia and during 1 h of recovery. Intravenous glucose tolerance test (IVGTT, 0.5 g glucose/kg) was performed after 1 h of anaesthesia. Glucose disappearance rate and areas under the insulin, C-peptide and glucagon curves from the IVGTT were calculated. All four anaesthetic protocols affected glucose metabolism parameters significantly compared with un-anaesthetised pigs, which was particularly evident during IVGTT and for TZMKB and KMX anaesthesia. Propofol additionally influenced the plasma concentrations of triglycerides, FFAs and glycerol significantly. The remaining circulating biomarkers were largely unaffected by anaesthesia. These data underline the importance of considering the anaesthetic protocol in porcine studies of circulating metabolic biomarkers.

Development of Silk Fibroin-Based Non-Crosslinking Thermosensitive Bioinks for 3D Bioprinting.

Three-dimensional (3D) bioprinting holds great promise for tissue engineering, allowing cells to thrive in a 3D environment. However, the applicability of natural polymers such as silk fibroin (SF) in 3D bioprinting faces hurdles due to limited mechanical strength and printability. SF, derived from the silkworm Bombyx mori, is emerging as a potential bioink due to its inherent physical gelling properties. However, research on inducing thermosensitive behavior in SF-based bioinks and tailoring their mechanical properties to specific tissue requirements is notably lacking. This study addresses these gaps through the development of silk fibroin-based thermosensitive bioinks (SF-TPBs). Precise modulation of gelation time and mechanical robustness is achieved by manipulating glycerol content without recourse to cross-linkers. Chemical analysis confirms β-sheet conformation in SF-TPBs independent of glycerol concentration. Increased glycerol content improves gelation kinetics and results in rheological properties suitable for 3D printing. Overall, SF-TPBs offer promising prospects for realizing the potential of 3D bioprinting using natural polymers.

Effect of Different Concentrations of Propylene Glycol and Glycerin on the Formulation of Guava Leaf (Psidium Guajava Linn.) Body Scrub with White Rice (Oryza sativa Linn.)

Guava leaves (Psidium guajava Linn.) have contents such as saponins, essential oils, tannins and anti-mutagenic and antioxidants which are ingredients that can reduce free radicals to cells. White rice (Oryza sativa Linn.) is a material that can be used as an abrasiver. Besides being easy to find, white rice also has a relatively cheap price, compared to brown rice or others. This study aims to determine the ethanol extract of guava leaves with white rice can be formulated and the effect of glycerine-propylenglycol in the preparation of body scrub cream with each concentration of 1%, 3%, and 5% and vice versa 5%, 3%, and 1% which are made in 3 formulas. The results obtained from the evaluation of the preparation are: Organoleptical test FI (green), FII and FIII (brown). Homogeneity test obtained by the three formulas is homogeneous, pH test obtained that all formulas meet the pH requirements of 4.5 - 6.5. The spreadability test obtained results in FI (3.1 cm), FII (3.2 cm), FIII (3.0 cm). As for the determination of the type (type) of emulsion obtained that all formulas have type m/a.

Effects of Diacetinmonoglycerides and Triacetin on Biodiesel Quality

Triacetin offers a higher added value compared to glycerol and can be obtained during the interesterification reaction between methyl acetate and triglycerides. In the same reaction, diacetinmonoglyceride is produced as an intermediate compound. The objective of this study was to assess whether the biodiesel produced, with varying concentrations of these compounds, meets the requirements established by the EN 14214 and ASTM D6751 standards. To achieve this, several properties were measured, including density, kinematic viscosity, cloud point, pour point, cold filter plugging point, methyl ester content, mono-, di-, triglyceride and total glycerol content, as well as the vacuum distillation curve. These measurements were conducted on mixtures of triacetin, diacetinmonoglyceride, and biodiesel, using different types of biodiesel such as palm, soybean, sunflower and rapeseed. Additionally, the solubility of these ternary mixtures in conventional diesel was evaluated. The results indicated that the EN 14214 standard imposes limits on the density and viscosity of biodiesel, restricting the content of triacetin (up to 5–10% by weight) and diacetinmonoglyceride (up to 3–4% by weight). However, the content of monoglycerides presents the most restrictive condition, as the chromatographic technique used cannot differentiate between monoglycerides and diacetinmonoglycerides. Consequently, their content is limited to a range of 0.15% to 0.70% by weight, depending on the prevailing climate conditions. Similarly, the ASTM D6751 standard sets a limitation of 0.40% by weight for monoglycerides to three out of six grades of biodiesel. Based on the findings of this study, which demonstrate that diacetinmonoglycerides do not have adverse effects on the cold performance of biodiesel, the inclusion of diacetinmonoglycerides in biodiesel production would still necessitate the development of standard test methods capable of differentiating between monoglycerides and diacetinmonoglycerides.

Effect of side group and crosslinking on the copolyesters as solvent-free pressure-sensitive adhesives

Pressure-sensitive adhesives (PSAs) are extensively employed in various applications due to their ability to instantly adhere upon the application of light pressure. Towards a sustainable future is the major driving force for the development of PSAs without solvent. In this study, a two-step melt polycondensation method was used to synthesize a series of copolyesters with varying contents of propanediol (PDO), 2-methyl-1,3-propanediol (MPO), and glycerol. These copolyesters were composed of different molar ratios of PDO/MPO (80/20, 50/50, and 20/80, respectively) and varying glycerol loading in polymer backbone (0, 0.5, and 1.0 mol%, respectively). The influence of the short side group from MPO and the slight crosslinking from glycerol on the thermal and rheological behavior of the copolyesters was investigated. The glass-transition temperature of these copolyesters range from −58.0 to −52.1 °C. Furthermore, the adhesive strength of these copolyesters was evaluated through T-peel and 180° peel testing. The 180° peel strength ranged from 81.1 to 600.6 Pa, while the T-peel strength ranged of 52.5–156.6 Pa. By adjusting the balance of side group and crosslinking content, it was possible to control the relationship between cohesion, adhesion, and tack. This study provides a potential material design for polyester-based and solvent-free PSAs.