Polymers

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16 pages, 1933 KiB

Open AccessArticle

Use of Fourier Series in X-ray Diffraction (XRD) Analysis and Fourier-Transform Infrared Spectroscopy (FTIR) for Estimation of Crystallinity in Cellulose from Different Sources

by Nicolás Montoya-Escobar, Daniel Ospina-Acero, Jorge Andrés Velásquez-Cock, Catalina Gómez-Hoyos, Angélica Serpa Guerra, Piedad Felisinda Gañan Rojo, Lina Maria Vélez Acosta, Juan Pablo Escobar, Natalia Correa-Hincapié, Omar Triana-Chávez, Robin Zuluaga Gallego and Pablo M. Stefani

Polymers 2022, 14(23), 5199; https://doi.org/10.3390/polym14235199 - 29 Nov 2022

Cited by 28 | Viewed by 8117

Abstract

Cellulose crystallinity can be described according to the crystal size and the crystallinity index (CI). In this research, using Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) methods, we studied the crystallinity of three different types of cellulose: banana rachis (BR), commercial cellulose [...] Read more.

Cellulose crystallinity can be described according to the crystal size and the crystallinity index (CI). In this research, using Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) methods, we studied the crystallinity of three different types of cellulose: banana rachis (BR), commercial cellulose (CS), and bacterial cellulose (BC). For each type of cellulose, we analyzed three different crystallization grades. These variations were obtained using three milling conditions: 6.5 h, 10 min, and unmilled (films). We developed a code in MATLAB software to perform deconvolution of the XRD data to estimate CI and full width at half-maximum (FWHM). For deconvolution, crystalline peaks were represented with Voigt functions, and a Fourier series fitted to the amorphous profile was used as the amorphous contribution, which allowed the contribution of the amorphous profile to be more effectively modeled. Comparisons based on the FTIR spectra and XRD results showed there were no compositional differences between the amorphous samples. However, changes associated with crystallinity were observed when the milling time was 10 min. The obtained CI (%) values show agreement with values reported in the literature and confirm the effectiveness of the method used in this work in predicting the crystallization aspects of cellulose samples. Full article

(This article belongs to the Special Issue Biopolymers Characterisation)

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24 pages, 30512 KiB

Open AccessArticle

Chemical, Thermal and Mechanical Characterization of Licorice Root, Willow, Holm Oak, and Palm Leaf Waste Incorporated into Maleated Polypropylene (MAPP)

by Serena Gabrielli, Miriam Caviglia, Genny Pastore, Enrico Marcantoni, Francesco Nobili, Luca Bottoni, Andrea Catorci, Irene Bavasso, Fabrizio Sarasini, Jacopo Tirillò and Carlo Santulli

Polymers 2022, 14(20), 4348; https://doi.org/10.3390/polym14204348 - 15 Oct 2022

Cited by 1 | Viewed by 2411

Abstract

The effect of four lignocellulosic waste fillers on the thermal and mechanical properties of biocomposites was investigated. Powdered licorice root, palm leaf, holm oak and willow fillers were melt compounded with polypropylene at two different weight contents, i.e., 10 and 30, and then [...] Read more.

The effect of four lignocellulosic waste fillers on the thermal and mechanical properties of biocomposites was investigated. Powdered licorice root, palm leaf, holm oak and willow fillers were melt compounded with polypropylene at two different weight contents, i.e., 10 and 30, and then injection molded. A commercially available maleated coupling agent was used to improve the filler/matrix interfacial adhesion at 5 wt.%. Composites were subjected to chemical (FTIR-ATR), thermal (TGA, DSC, DMA) and mechanical (tensile, bending and Charpy impact) analyses coupled with a morphological investigation by scanning electron microscopy. Although similarities among the different formulations were noted, holm oak fillers provided the best combination of thermal and mechanical performance. In particular, at 30 wt.% content with coupling agent, this composite formulation displayed remarkable increases in tensile strength and modulus, flexural strength and modulus, of 28% and 110%, 58% and 111%, compared to neat PP, respectively. The results imply that all these lignocellulosic waste fillers can be used successfully as raw materials for biocomposites, with properties comparable to those featured by other natural fillers. Full article

(This article belongs to the Special Issue Biopolymers Characterisation)

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19 pages, 4413 KiB

Open AccessArticle

Formulation and Characterization of Gum Arabic Stabilized Red Rice Extract Nanoemulsion

by Aarti Bains, Agnieszka Najda, Prince Chawla, Joanna Klepacka, Sanju Bala Dhull, Pardeep Kumar Sadh, Mohammed Azhar Khan and Ravinder Kaushik

Polymers 2022, 14(10), 1938; https://doi.org/10.3390/polym14101938 - 10 May 2022

Cited by 9 | Viewed by 2574

Abstract

Interest in the utilization of plant-based bioactive compounds in foods has increased due to their biochemical activities and as alternatives in the reduction of high concentrations of chemical utilization. However, some of these additives are hydrophobic, thus being harder to disperse into the [...] Read more.

Interest in the utilization of plant-based bioactive compounds in foods has increased due to their biochemical activities and as alternatives in the reduction of high concentrations of chemical utilization. However, some of these additives are hydrophobic, thus being harder to disperse into the hydrophilic food matrix. Therefore, an oil-in-water nanoemulsion (RRE1-RRE10) was formulated with different concentrations of red rice extract (1–10% w/v). Nanoemulsion showed droplet sizes within the range of 157.33–229.71 nm and the best formulation (RRE5) was selected based on the creaming index which was stable to flocculation over a range of temperatures (30–90 °C), pH (2–9), and salt concentration (100–600 mM). It showed significantly improved antioxidant and anti-inflammatory activity as compared to its other counterparts. Potential antimicrobial activity against Staphylococcus aureus was attributed to RRE5 nanoemulsion as compared to Escherichia coli. Therefore, due to the potential bioactivity of RRE5 nanoemulsion, it can be scaled up at the industrial level. Full article

(This article belongs to the Special Issue Biopolymers Characterisation)

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16 pages, 3164 KiB

Open AccessArticle

Biodegradable, Stretchable and Transparent Plastic Films from Modified Waterborne Polyurethane Dispersions

by Uttam C. Paul, Gözde Bayer, Silvia Grasselli, Annalisa Malchiodi and Ilker S. Bayer

Polymers 2022, 14(6), 1199; https://doi.org/10.3390/polym14061199 - 16 Mar 2022

Cited by 7 | Viewed by 4702

Abstract

Waterborne polyurethane dispersions can be designed to generate highly functional and environmentally friendly polymer systems. The use of water as the main dispersion medium is very advantageous for the environment and the introduction of linear and aliphatic polyols such as polyether and polyesters [...] Read more.

Waterborne polyurethane dispersions can be designed to generate highly functional and environmentally friendly polymer systems. The use of water as the main dispersion medium is very advantageous for the environment and the introduction of linear and aliphatic polyols such as polyether and polyesters in the formulations can make them highly biocompatible and susceptible to biodegradation. In this study, we fabricated biodegradable, flexible and transparent plastic films by hybridizing a waterborne aliphatic polyester polyurethane (PU) suspension with polyvinylpyrrolidone (PVP) using mechanical homogenization in water. Films were cast containing different concentrations of PVP. The hybrids containing 50 wt.% PVP (PU/PVP_50/50) were hydrophobic, stretchable, highly transparent and ductile beyond 100% strain compared to highly brittle PVP. The mechanical properties of the PU/PVP_50/50 film remained stable after repeated immersion wet–dry cycles, each lasting 2 days, and the dried films recovered their mechanical properties after each cycle. Based on a 28-day biochemical oxygen demand (BOD) test, the hybrid PU/PVP_50/50 film underwent extensive biodegradation. This simple but effective process can be very suitable in producing biodegradable ductile films with very good transparency that can serve a number of applications such as agricultural mulches, food and pharmaceutical packaging and biomedical field. Full article

(This article belongs to the Special Issue Biopolymers Characterisation)

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14 pages, 884 KiB

Open AccessArticle

The Effect of Chitosan Type on Biological and Physicochemical Properties of Films with Propolis Extract

by Karolina Stanicka, Renata Dobrucka, Magdalena Woźniak, Anna Sip, Jerzy Majka, Wojciech Kozak and Izabela Ratajczak

Polymers 2021, 13(22), 3888; https://doi.org/10.3390/polym13223888 - 10 Nov 2021

Cited by 15 | Viewed by 2430

Abstract

The aim of the research was to determine the influence of chitosan type and propolis extract concentration on biological and physicochemical properties of chitosan-propolis films in terms of their applicability in food packaging. The films were prepared using three types of chitosan: from [...] Read more.

The aim of the research was to determine the influence of chitosan type and propolis extract concentration on biological and physicochemical properties of chitosan-propolis films in terms of their applicability in food packaging. The films were prepared using three types of chitosan: from crab shells, medium and high molecular weight and propolis concentration in the range of 0.75–5.0%. The prepared polysaccharide films were tested for antimicrobial properties, oxygen transmission rate (OTR) and water vapor transmission rate (WVTR). Moreover, sorption tests and structural analysis were carried out. Microbiological tests indicated the best antimicrobial activity for the film consisting of high molecular weight chitosan and 5.0% propolis extract. Both the type of chitosan and propolis concentration affected transmission parameters—OTR and WVTR. The best barrier properties were recorded for the film composed of high molecular weight chitosan and 5.0% propolis extract. The results of sorption experiments showed a slight influence of chitosan type and a significant effect of propolis extract concentration on equilibrium moisture content of tested films. Moreover, propolis extract concentration affected monolayer water capacity (Mm) estimated using the Guggenheim, Anderson and de Boer (GAB) sorption model. The obtained results indicate that chitosan films with an addition of propolis extract are promising materials for food packaging applications, including food containing probiotic microorganisms. Full article

(This article belongs to the Special Issue Biopolymers Characterisation)

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12 pages, 3581 KiB

Open AccessEditor’s ChoiceArticle

Elastic and Dynamic Heterogeneity in Aging Alginate Gels

by Raffaele Pastore, Ciro Siviello and Domenico Larobina

Polymers 2021, 13(21), 3618; https://doi.org/10.3390/polym13213618 - 20 Oct 2021

Cited by 4 | Viewed by 2016

Abstract

Anomalous aging in soft glassy materials has generated a great deal of interest because of some intriguing features of the underlying relaxation process, including the emergence of “ultra-long-range” dynamical correlations. An intriguing possibility is that such a huge correlation length is reflected in [...] Read more.

Anomalous aging in soft glassy materials has generated a great deal of interest because of some intriguing features of the underlying relaxation process, including the emergence of “ultra-long-range” dynamical correlations. An intriguing possibility is that such a huge correlation length is reflected in detectable ensemble fluctuations of the macroscopic material properties. We tackle this issue by performing replicated mechanical and dynamic light scattering (DLS) experiments on alginate gels, which recently emerged as a good model-system of anomalous aging. Here we show that some of the monitored quantities display wide variability, including large fluctuations in the stress relaxation and the occasional presence of two-step decay in the DLS decorrelation functions. By quantifying elastic fluctuation through the standard deviation of the elastic modulus and dynamic heterogeneities through the dynamic susceptibility, we find that both quantities do increase with the gel age over a comparable range. Our results suggest that large elastic fluctuations are closely related to ultra-long-range dynamical correlation, and therefore may be a general feature of anomalous aging in gels. Full article

(This article belongs to the Special Issue Biopolymers Characterisation)

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18 pages, 21482 KiB

Open AccessArticle

Evaluation and Characterization of Tamarind Gum Polysaccharide: The Biopolymer

by Rishabha Malviya, Sonali Sundram, Shivkanya Fuloria, Vetriselvan Subramaniyan, Kathiresan V. Sathasivam, Abul Kalam Azad, Mahendran Sekar, Darnal Hari Kumar, Srikumar Chakravarthi, Omji Porwal, Dhanalekshmi Unnikrishnan Meenakshi and Neeraj Kumar Fuloria

Polymers 2021, 13(18), 3023; https://doi.org/10.3390/polym13183023 - 7 Sep 2021

Cited by 53 | Viewed by 6390

Abstract

Polymers from natural sources are widely used as excipients in the formulation of pharmaceutical dosage forms. The objective of this study was to extract and further characterize the tamarind gum polysaccharide (TGP) obtained from Tamarindus indica as an excipient for biomedical applications. Double [...] Read more.

Polymers from natural sources are widely used as excipients in the formulation of pharmaceutical dosage forms. The objective of this study was to extract and further characterize the tamarind gum polysaccharide (TGP) obtained from Tamarindus indica as an excipient for biomedical applications. Double distilled water was used as a solvent for the extraction of gum while Ethyl alcohol was used as an antisolvent for the precipitation. The results of the Hausner ratio, Carr’s index and angle of repose were found to be 0.94, 6.25, and 0.14, respectively, which revealed that the powder is free-flowing with good flowability. The gum was investigated for purity by carrying out chemical tests for different phytochemical constituents and only carbohydrates were found to be present. The swelling index was found to be 87 ± 1%, which shows that TGP has good water intake capacity. The pH of the 1% gum solution was found to be neutral, approximately 6.70 ± 0.01. The ash values such as total ash, sulphated ash, acid insoluble ash, and water-soluble ash were found to be 14.00 ± 1.00%, 13.00 ± 0.05%, 14.04 ± 0.57% and 7.29 ± 0.06%, respectively. The IR spectra confirmed the presence of alcohol, amines, ketones, anhydrides groups. The contact angle was <90°, indicating favorable wetting and good spreading of liquid over the surface The scanning electron micrograph (SEM) revealed that the particle is spherical in shape and irregular. DSC analysis shows a sharp exothermic peak at 350 °C that shows its crystalline nature. The results of the evaluated properties showed that TGP has acceptable properties and can be used as a excipient to formulate dosage forms for biomedical applications. Full article

(This article belongs to the Special Issue Biopolymers Characterisation)

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Review

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20 pages, 1522 KiB

Open AccessReview

Sulfated Polysaccharides from Macroalgae—A Simple Roadmap for Chemical Characterization

by Alice Martins, Celso Alves, Joana Silva, Susete Pinteus, Helena Gaspar and Rui Pedrosa

Polymers 2023, 15(2), 399; https://doi.org/10.3390/polym15020399 - 12 Jan 2023

Cited by 8 | Viewed by 3407

Abstract

The marine environment presents itself as a treasure chest, full of a vast diversity of organisms yet to be explored. Among these organisms, macroalgae stand out as a major source of natural products due to their nature as primary producers and relevance in [...] Read more.

The marine environment presents itself as a treasure chest, full of a vast diversity of organisms yet to be explored. Among these organisms, macroalgae stand out as a major source of natural products due to their nature as primary producers and relevance in the sustainability of marine ecosystems. Sulfated polysaccharides (SPs) are a group of polymers biosynthesized by macroalgae, making up part of their cell wall composition. Such compounds are characterized by the presence of sulfate groups and a great structural diversity among the different classes of macroalgae, providing interesting biotechnological and therapeutical applications. However, due to the high complexity of these macromolecules, their chemical characterization is a huge challenge, driving the use of complementary physicochemical techniques to achieve an accurate structural elucidation. This review compiles the reports (2016–2021) of state-of-the-art methodologies used in the chemical characterization of macroalgae SPs aiming to provide, in a simple way, a key tool for researchers focused on the structural elucidation of these important marine macromolecules. Full article

(This article belongs to the Special Issue Biopolymers Characterisation)

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29 pages, 2714 KiB

Open AccessReview

Regenerated Cellulose Products for Agricultural and Their Potential: A Review

by Nur Amira Zainul Armir, Amalia Zulkifli, Shamini Gunaseelan, Swarna Devi Palanivelu, Kushairi Mohd Salleh, Muhamad Hafiz Che Othman and Sarani Zakaria

Polymers 2021, 13(20), 3586; https://doi.org/10.3390/polym13203586 - 18 Oct 2021

Cited by 43 | Viewed by 7930

Abstract

Cellulose is one of the most abundant natural polymers with excellent biocompatibility, non-toxicity, flexibility, and renewable source. Regenerated cellulose (RC) products result from the dissolution-regeneration process risen from solvent and anti-solvent reagents, respectively. The regeneration process changes the cellulose chain conformation from cellulose [...] Read more.

Cellulose is one of the most abundant natural polymers with excellent biocompatibility, non-toxicity, flexibility, and renewable source. Regenerated cellulose (RC) products result from the dissolution-regeneration process risen from solvent and anti-solvent reagents, respectively. The regeneration process changes the cellulose chain conformation from cellulose I to cellulose II, leads the structure to have more amorphous regions with improved crystallinity, and inclines towards extensive modification on the RC products such as hydrogel, aerogel, cryogel, xerogel, fibers, membrane, and thin film. Recently, RC products are accentuated to be used in the agriculture field to develop future sustainable agriculture as alternatives to conventional agriculture systems. However, different solvent types and production techniques have great influences on the end properties of RC products. Besides, the fabrication of RC products from solely RC lacks excellent mechanical characteristics. Thus, the flexibility of RC has allowed it to be homogenously blended with other materials to enhance the final products’ properties. This review will summarize the properties and preparation of potential RC-based products that reflect its application to replace soil the plantation medium, govern the release of the fertilizer, provide protection on crops and act as biosensors. Full article

(This article belongs to the Special Issue Biopolymers Characterisation)

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