Effect of Manufacturing Process and Xanthan Gum Addition on the Properties of Cassava Starch Films

The objective of this work was to manufacture biodegradable films by two different processes (casting and extrusion), from different combinations of cassava starch and xanthan gum. These films were produced by casting and by extrusion from six different starch-xanthan gum combinations (0, 2, 4, 6, 8 and 10% w/w), containing glycerol as plasticizer (20% w/w) and were also characterized according to their microstructure, optical, mechanical, and barrier properties. Scanning electron microscopy of the starch-xanthan gum extruded films showed reticulated surface and smooth interior, suggesting that xanthan was driven to the surface and gelatinized starch to the interior of the films during extrusion. Films manufactured by casting were entirely homogeneous. In general, casted films presented lower opacity and water vapor permeability and higher stress at break than films manufactured by extrusion. Xanthan gum addition affected mechanical properties of starch films, improving their stress and strain at break, especially for extruded samples, but these properties did not show stability at different RH conditions.     

Development of a Natural Chewing Gum from Plant Based Polymer

In this study, Kenger gum obtained from Kenger plant (Gundelia tournefortii) was used in the production of biodegradable and edible chewing gum. Kenger gum was able to be softened by thermal process to improve its textural properties. 80% methanolic extract of gum showed 195.6 gallic acid equivalents (GAE) mg/100 g gum antioxidant activity and 17.9 mm inhibition zone for Escherichia coli O157:H7 as an antimicrobial activity. Softened Kenger gum was also characterized by texture properties, scanning electron microscope (SEM) images and chemical compositions. Hardness value of gum decreased from 864 to 238 g which was comparable to commercial chewing gums. Softened Kenger gum was observed to be a perfect substitute for a synthetic gum base in the production of a conventional chewing gum. Moreover, resilience value was remarkably found to be the best standard parameter to select chewing gums with desired textural properties.     

Synergistic Effect of TNPP and Carbon Black in Weathered XLPE Materials

Carbon black is one of the most widely used and most effective ultraviolet (UV) light stabilizers for plastics applications. Several important segments of the plastics industry rely on carbon black for UV stabilization of weather-resistant products, including telecommunications, power cable jacketing, and plastic pipes. In this research work a combination of Trisnonylphospate (TNPP) antioxidant and different size carbon black were applied in crosslinked polyethylene (XLPE) to improve its wetherability. The primary reason for cross-linking polyethylene (PE) is to raise the thermal stability of the material under load. This substantially improves environmental stress crack resistance and resistance to slow crack growth. The results achieved of this additive package combination show a synergism effect and improved weatherability of electrical cable. Increased weathering lifetime was also achieved. Further, we were able to confirm in this work, that the size and quality of the carbon black dispersion in a XLPE samples is an important component of both the UV-resistance and mechanical properties of the finished plastic article. Incremental improvements of carbon black dispersion can positively influence the expected life of plastic articles. Mechanical testing and FTIR were used to detect degradation of the accelerated weathered XLPE samples. The morphological considerations of UV energy absorption and presents laboratory data demonstrating the link between dispersion and weatherability as well as between morphology and weatherability     

Production and Characterization of Sodium Alginate/Gum Arabic Based Films Enriched with Syzygium cumini Seeds Extracts for Food Application

Journal of Polymers and the Environment - Biodegradable sodium alginate/gum Arabic (SG) films were obtained. The influence of Syzygium cumini seeds extract (SCSE) incorporation in SG films on...     

Use of Oxidation Onset Temperature Measurements for Evaluating the Oxidative Degradation of Isotatic Polypropylene

The widespread use of polymeric materials in many applications requires polymers that are weather resistant. The aim of this study is to examine the usefulness of oxidation onset temperature measurements as a tool for evaluating oxidative degradation of isotatic polypropylene. Differential scanning calorimetry was used to measure the oxidation onset temperature in formulations of isotatic polypropylene containing different concentrations of light and thermal stabilizers after aging in a Weather-Ometer. Oxidation onset temperature gave better results than oxidation induction time for evaluating the degradation of isotatic polypropylene during aging in a Weather-Ometer. However, both tests showed a poor correlation with the appearance of cracks seen by optical microscopy.     

Effect of Museum Conditions on Historical Dyed Silk Fabric with Madder Dye

Historical textiles suffer from deterioration as a result of exposure to uncontrolled environmental conditions in museums. To establish standard conditions for display of undyed and dyed silk fabrics in Egyptian museums, different artificial aging procedures (thermal, light and chemical) were applied to examine their effects on the physical, mechanical and chemical structure of the silk fiber. Samples of undyed silk and silk dyed with madder with different mordants, iron II sulphate; iron III chloride and copper sulphate were used for this purpose. These aged samples were examined for their surface morphology, color parameters (CIE Lab), mechanical properties, degree of crystallinity, secondary structure analysis and amino acids content.     

Effect of Hydrothermal Aging on Injection Molded Short Jute Fiber Reinforced Poly(Lactic Acid) (PLA) Composites

This work focused on the durability of short jute fiber reinforced poly(lactic acid) (PLA) composites in distilled water at different temperatures (23, 37.8 and 60 °C). Morphological, thermal and mechanical properties (tensile, flexural, and impact) of jute/PLA composites were investigated before and after aging. Different from traditional synthetic fiber reinforced polymer composites, the stability of jute/PLA composites in water was significantly influenced by hydrothermal temperature. The mechanical properties of the composites and molecular weight of PLA matrix declined quickly at 60 °C, however, this process was quite slower at temperatures of 23 and 37.8 °C. Impact properties of the composites were hardly decreased, but the tensile and flexural properties suffered a drop though to various degrees with three degradation stages at 23 and 37.8 °C. The poor interface of composites and the degradation of PLA matrix were the main damage mechanism induced by hydrothermal aging. Furthermore, considering the hydrolysis of PLA matrix, the cleavage of PLA molecular chain in different aging time was quantitatively investigated for the first time to illustrate hydrolysis degree of PLA matrix at different aging time.     

Development of Hybrid Film Based on Carboxymethyl Chitosan-Gum Arabic Incorporated Citric Acid and Polyphenols from Cinnamomum camphora Seeds for Active Food Packaging

Journal of Polymers and the Environment - In this study, carboxymethyl chitosan with gum Arabic (CG) based novel functional films containing Cinnamomum camphora seeds extract (CCSE) at varying...     

Physicochemical and Antibacterial Evaluation of Poly (Vinyl Alcohol)/Guar Gum/Silver Nanocomposite Films for Food Packaging Applications

Journal of Polymers and the Environment - In this study, we prepared Poly (vinyl alcohol) (PVA)/Guar gum (GG) based nanocomposite films with a different weight ratio of silver nanoparticles (AgNPs)...     

Novel Biodegradable Cast Film from Cherry Tree Gum,Development, Modification and Characterization

The feasibility of sweet cherry gum as a bio-based film-forming material and effect of hydrogen peroxide as a chemical modifier investigated. The influence of film compositions (gum, glycerol) and hydrogen peroxide on the physical properties of films, including solubility in water, permeability to water vapor (WVP), mechanical properties, and transparency, thermal and microstructural properties evaluated. The results showed that WVP and thickness increased by gum and glycerol concentration, but significantly decreased by hydrogen peroxide. As expected, elongation-at-break and solubility, increased at higher concentration of glycerol but the tensile strength decreased at the same condition. The film transparency was influenced by the dry weight content and was improved by higher concentrations of hydrogen peroxide. The partial degradation of polymer chain by hydrogen peroxide was observed by FTIR analysis.     

Effects of Weathering on Mechanical,Antimicrobial Properties and Biodegradation Process of Silver Loaded TPE Compounds

The incorporation of antimicrobial metals such as silver is an alternative to protect the material against microbial attack. However, loaded polymer can lose its antimicrobial properties after some time of use, and the additive may even leak out into the environment becoming harmful to non-target organisms. This study aims to evaluate the mechanical properties and antimicrobial activity of silver containing thermoplastic elastomer (TPE) samples exposed to weathering and the influence of additive incorporation in material biodegradation in the soil. For this purpose, silver ions (Ag⁺_bentonite, Ag⁺_phosphate) and silver nanoparticles (AgNp_silica) based additives were blended in a formulation of SEBS, polypropylene and mineral oil. The test samples were exposed to natural ageing over nine months, and were then evaluated according to their mechanical properties, antimicrobial activity, and degree of crystallinity and surface characteristics. The biodegradation process before and after natural ageing was evaluated through the generation of carbon dioxide. The results show that the action of natural ageing reduced the mechanical properties of loaded and unloaded TPE, and modified the degree of crystallinity and the chemical characteristic of the TPE surface. The presence or type of additive did not influence material resistance after being exposed to weathering. A decrease in antimicrobial activity in samples after natural ageing was observed. At a variable level and according to the chemical content, generation of carbon dioxide from TPE samples was greater in aged samples than in unexposed ones.     

Natural Weathering Studies of Polypropylene

Polypropylene (PP) has achieved a dominating position and hence, their consumption increases thereby littering, which lead to environmental pollution. Photodegradation seems to be a better choice because of naturally available sunlight as energy source for degradation. The present work involves the study of the variation of degradation behavior of PP film during tropical summer and winter seasons. The photodegradation is followed by Fourier transform infrared (FTIR) spectroscopic technique. Various indices like hydroxyl, carbonyl, vinylidene, lactones, ester, carboxylic acid and crystallinity are calculated and these values increased after a brief induction period. The variation in the mechanical properties like tensile strength and elongation at break percentages are determined. The scanning electron microscopic (SEM) images of weathered PP showed surface cracks when carbonyl index value increases sharply and the mechanical properties show a sudden decrease. Attempted life time prediction using mathematical models showed that the carbonyl growth is more affected by ultraviolet (UV) and cumulative total solar radiation for PP weathered during summer. The loss in tensile strength of PP weathered during summer is more dependent on the average temperature and the UV portion of the total solar radiation whereas, intensity of UV radiation has profound effect on the tensile strength of PP weathered during winter.     

In Vivo and In Vitro Degradation Studies for Poly(3-hydroxybutyrate-<Emphasis Type="Italic">co</Emphasis>-3-hydroxyhexanoate) Biopolymer

Studies have shown that the copolymer poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) [P(HB-co-HHx)] possesses favorable mechanical properties for use in medical supplies and products (e.g., sutures, scaffolds, bone plates). One of the major under-addressed issues associated with the use of biodegradable, bio-based PHA polymers in resorbable medical products is the correlation between the mechanical properties and the in vivo material degradation over time. In this study, P(HB-co-17 mol% HHx) matrices were mechanically tested after either incubation in cultures of human embryonic kidney cells (HEK) for in vitro degradation studies for up to 4 weeks, or inserted into Danio rerio (zebrafish) tissues for in vivo degradation studies for up to 7 weeks. The mechanical properties and scanning electron microscopy (SEM) images of the degraded materials were examined and later correlated to understand the degradation phenomenon. Our results show that Young’s modulus of P(HB-co-17 mol%HHx) during in vitro studies decreased from 3.26 to 2.42 GPa within 4 weeks, and in vivo breakdown resulted in a significant decrease in Young’s modulus with a decrease from 3.26 to 0.51 GPa and a mass loss of 59 % within 7 weeks. SEM images showed the development of pores and cracks on the surface of the material over time. Plasticization and recrystallization were observed and likely play a role in the alteration of mechanical properties.     

Effect of Magnesium Oxide Loading on Adhesion Properties of ENR 25/NBR Blend Adhesives in the Presence of Petro Resin and Gum Rosin Tackifiers

The adhesion properties of magnesium oxide filled epoxidized natural rubber (ENR 25)/acrylonitrile-butadiene rubber (NBR) blend adhesives were studied using petro resin and gum rosin as tackifiers. Toluene was used as the solvent throughout the experiment. Five different loadings, i.e. 10, 20, 30, 40 and 50 phr magnesium oxide was used in the adhesive formulation. The SHEEN hand coater was used to coat the adhesive on polyethylene terephthalate at 30 and 120 µm coating thickness. The tack, peel strength and shear strength were determined by a Lloyd adhesion tester operating at 30 cm min^?1. Results shows that all the adhesion properties of the ENR 25/NBR adhesives show a maximum value at 10 phr filler loading. Loop tack and peel strength pass through a maximum, an observation which is associated to the optimum wettability of adhesive on the substrate. For the shear test, maximum shear strength occurs due to the optimum cohesive strength of the adhesive. Results also show that all petro resin based adhesives have higher adhesion properties than gum rosin based adhesive. In all cases, the adhesion properties of adhesives also increase with increasing coating thickness.     

Preparation of Cellulose/Xanthan Gum Composite Films and Hydrogels Using Ionic Liquid

This paper reports the preparation of cellulose/xanthan gum composite films and hydrogels through gelation with an ionic liquid. Mixtures of cellulose and xanthan gum in desired weight ratios with an ionic liquid, 1-butyl-3-methylimidazolium chloride (BMIMCl), were thinly placed on a Petri dish and heated at 100 °C for 9 h to obtain the solutions. Then, the solutions were left standing at room temperature for 1 day for the progress of gelation. The resulting ion gels were subjected to Soxhlet extraction with ethanol to remove BMIMCl, followed by drying under ambient conditions to obtain the composite films. The crystalline structures of the polysaccharides and the mechanical properties were evaluated by powder X-ray diffraction measurement and tensile testing of the films, respectively. The ion gels in various cellulose/xanthan gum weight ratios, which were prepared in a test tube by the same procedure, were immersed in water for the exchange of disperse media to obtain the cellulose/xanthan gum composite hydrogels. Water contents of all the materials were higher than 90 %. The mechanical properties of the hydrogels were evaluated by compressive testing.     

Formulation of a Photosensitized Polyethylene Film; Its Structure and Property Variation Under the Weathering Conditions of Tehran

To develop an environmentally degradable polymer material, a masterbatch pro-oxidant system was blended into low-density polyethylene. The polymer film samples were prepared by compression molding. The prepared films were placed under the natural environment of Tehran for weathering studies and accelerated conditions were also performed for UV aging in UV chamber. At different time intervals, the changes in chemical structure of photosensitized polyethylene samples were studied by FTIR and compared to that of the control polyethylene films. Also the mechanical properties of photosensitized polyethylene films were determined in comparison with the control films by measuring the tensile strength and elongation at break after exposure to the natural environment and UV radiation. Results showed that the overall rate of degradation process is clearly dependent on the polyethylene composition, test conditions (natural or accelerated), season of the year, and the duration of the weathering of the samples.     

Effect of the Pretreatment with UV and Gamma Radiations on the Modification of Plywood Surface by Photocuring with Epoxy Acrylate

In order to further improve the physical properties of plywood surface that was pretreated with UV and Gamma radiation at different radiation intensities before photocuring. After pretreatment with radiation the plywood surface was coated with different prepared formulations containing epoxyacrylate (EA-1020) as an oligomer, difunctional monomers such as tripropylene glycol diacrylate (TPGDA), 2-hexadioldiacrylate (HDDA), Ethylene Glycol dimethacrylate (EGDMA) and trifunctional monomer trimethyl propen triacrylate (TMPTA) with photoinitiator Darocur 1664. Thin polymer films were prepared on glass plate with these formulated solutions and cured under UV radiation. Pendulum hardness (PH) and gel content of the film were studied for selecting the formulations as top coat and as base coat. The polished plywood surface was coated with selected formulation and cured under UV radiation. Various rheological properties of UV cured plywood surface such as pendulum hardness, scratch hardness, microgloss, adhesion strength, percentage chipped off area and abrasion resistance were studied.     

Potential of <Emphasis Type="Italic">pinhão</Emphasis> Coat as Constituents of Starch Based Films Using Modification Techniques

The potential of lignocellulosic fibers obtained by dry grinding of pinhão coat as fillers in starch filmogenic solutions for packaging applications was evaluated in this work. To improve the incorporation of this waste into the starch solutions different physical and chemical treatments were conducted. Thereafter, morphology, chemical structure, crystallinity and water absorption of the pinhão coat powders were determined. The composites were also characterized regarding their morphology, chemical structure, crystallinity, mechanical properties, water vapor permeability and hydrophilicity. Poor fiber/matrix adhesion and high water absorption of the fibers were evidenced. Consequently, water vapor permeability of composites was increased by incorporating the fibers. Moreover, mechanical properties were improved and the morphological results were used to support the water absorption differences among the powders. Regarding the food packaging applications, starch/pinhão coat composites appeared as promising materials to reach the requirements of respiring food products.     

Dynamic Mechanical Properties of Soy Protein Filled Elastomers

Dynamic mechanical properties including temperature effect, stress softening, and Payne effect are studied on the elastomer composites filled with soy protein or carbon black. The comparison of protein composite with well-known carbon black composites provides further insight into the protein composites. The elastomers filled with soy protein aggregates give substantial reinforcement effect when compared with the unfilled elastomers. Approximately 400 times increase in shear elastic modulus was observed when 40% by weight of protein is incorporated into the elastomers. The sample films were cast from the particle dispersion of soy protein isolate and carboxylated styrene–butadiene latex. At the higher temperatures, the shear elastic modulus of soy protein-filled composites does not decrease as much as that of the carbon black-filled composites. The behavior of elastic and loss modulus under the oscillatory strain of different magnitude is similar to that of carbon black reinforced styrene–butadiene rubber. However, carbon black composites show a better recovery behavior after eight cycles of dynamic strain. The reduction of shear elastic modulus with dynamic strain (Payne effect) was compared with Kraus model and the fitting parameter related to the aggregate structure of the soy protein. A reasonable agreement between the theoretical model and experiment was obtained, indicating the Payne effect of the protein-related network structure in the elastomers could also be described by the kinetic agglomeration de-agglomeration mechanism.     

A Comparative Study Between Technological Properties of Cashew Tree Gum and Arabic Gum

Arabic gum (AG) is the most common emulsifier used for beverage emulsions. Cashew tree gum (CG) is a biological macromolecule that has been proposed as a substitute for the AG, although their technological properties comparison is still necessary. The aim of this study was to evaluate an isolation method for CG, and then evaluate CG technological properties in comparison to AG. The CG isolation methodology was improved using a small solvent amount. CG zeta-potential ranged from +8.0 mV (pH 2) to ?9.7 mV (pH 5), while the electric charge in solution of AG ranged from ?2.7 mV (pH 2) to ?28.6 mV (pH 6). As compared to AG, the CG showed a 50 % higher swelling, a 36 % lower oil absorption capacity, a slightly lower (4–8 %) solubility and lower consistency. CG is a feasible polyelectrolyte, promotes lower consistency solutions, and exhibits good swelling property.