“…Besides that, the hydrolysis TPCS chain will increase the number of hydroxyl groups exposed to contact with water molecules and increase the WVP. 58…”
Section: Resultsmentioning
confidence: 99%
“…Besides that, the hydrolysis TPCS chain will increase the number of hydroxyl groups exposed to contact with water molecules and increase the WVP. 58 Meanwhile, for CR-4B1C films, the WVP experienced a decrease as the pH value increased. The different WVP trends observed in CR-4B1C films indicated that the hydrolysis of films was non-exists with the addition of the hybrid filler, and a different cross-linked structure was expected.…”
Section: Solubility and Swelling Of Cr-tpcs And Cr-4b1c In Dmsomentioning
Thermoplastic starch (TPS) suffers from its intrinsic low mechanical strength and high brittleness due to its strong hydrogen bonding and low chain mobility. The conventional way to crosslink the TPS film can improve the strength and stiffness of the films, but usually reduces the flexibility of the film, and increases its brittleness. In this study, the incorporation of the hybrid nanofiller [1 wt% nanocellulose (C) and 4 wt% nano bentonite (B)] into the TPS proved to improve greatly the films’ strength and flexibility. The hybrid nanofillers with ratio 4B:1C was incorporated into the crosslinked thermoplastic corn starch (CR-TPCS) film to increase the its flexibility and toughness and produced a high mechanical strength fully biodegradable film. Two different aqueous carboxylic acids: citric acid (CA) and tartaric acid (TA) with different pH values (2,4,6) as the green crosslinker were employed. Substantial increase of tensile strength (3.98 to 9.17 MPa), Young’s modulus (9.10 to 46.30 MPa) and elongation at break (55.2 to 135.7%) was observed for the CA- 4B1C/pH2 films compared to the CR-TPCS films. The melting temperature (Tm) of the CA-4B1C/pH2 improved compared to the TPCS/4B1C (un-crosslinked) film due to its crosslinking effect. Meanwhile, the CA-4B1C films exhibited the highest degree of substitution and di-esterification with the lowest swelling and water solubility properties due to the formation of a special “bridge” structure between the CA, nanocellulose and plasticizer. The “bridge” structure developed between the TPCS chains serves as the toughener to motivate higher chain stress relaxation and load endurance. The crosslinked “bridge structure” also proved to effectively reduce the retrogradation phenomenal in the TPCS films. This combination method of hybridization and crosslinking is an efficient, low cost, and environmentally friendly technique to overcome the low flexibility and brittleness problem of the TPS based packaging film.
“…Besides that, the hydrolysis TPCS chain will increase the number of hydroxyl groups exposed to contact with water molecules and increase the WVP. 58…”
Section: Resultsmentioning
confidence: 99%
“…Besides that, the hydrolysis TPCS chain will increase the number of hydroxyl groups exposed to contact with water molecules and increase the WVP. 58 Meanwhile, for CR-4B1C films, the WVP experienced a decrease as the pH value increased. The different WVP trends observed in CR-4B1C films indicated that the hydrolysis of films was non-exists with the addition of the hybrid filler, and a different cross-linked structure was expected.…”
Section: Solubility and Swelling Of Cr-tpcs And Cr-4b1c In Dmsomentioning
Thermoplastic starch (TPS) suffers from its intrinsic low mechanical strength and high brittleness due to its strong hydrogen bonding and low chain mobility. The conventional way to crosslink the TPS film can improve the strength and stiffness of the films, but usually reduces the flexibility of the film, and increases its brittleness. In this study, the incorporation of the hybrid nanofiller [1 wt% nanocellulose (C) and 4 wt% nano bentonite (B)] into the TPS proved to improve greatly the films’ strength and flexibility. The hybrid nanofillers with ratio 4B:1C was incorporated into the crosslinked thermoplastic corn starch (CR-TPCS) film to increase the its flexibility and toughness and produced a high mechanical strength fully biodegradable film. Two different aqueous carboxylic acids: citric acid (CA) and tartaric acid (TA) with different pH values (2,4,6) as the green crosslinker were employed. Substantial increase of tensile strength (3.98 to 9.17 MPa), Young’s modulus (9.10 to 46.30 MPa) and elongation at break (55.2 to 135.7%) was observed for the CA- 4B1C/pH2 films compared to the CR-TPCS films. The melting temperature (Tm) of the CA-4B1C/pH2 improved compared to the TPCS/4B1C (un-crosslinked) film due to its crosslinking effect. Meanwhile, the CA-4B1C films exhibited the highest degree of substitution and di-esterification with the lowest swelling and water solubility properties due to the formation of a special “bridge” structure between the CA, nanocellulose and plasticizer. The “bridge” structure developed between the TPCS chains serves as the toughener to motivate higher chain stress relaxation and load endurance. The crosslinked “bridge structure” also proved to effectively reduce the retrogradation phenomenal in the TPCS films. This combination method of hybridization and crosslinking is an efficient, low cost, and environmentally friendly technique to overcome the low flexibility and brittleness problem of the TPS based packaging film.
“…Therefore, the improving tendency of strength value of citric acid-filled based foams prepared in this study could suggest the appearance of citric acid esterified crosslinking starch chains. However, the decreasing tendency of the strength of the citric acid-filled based foams (GLCA4 and GLCA5) could be ascribed to the excess of citric acid that could have acted as a plasticizer for the starch, 29–31 which softened and lowered the flexural strength of the starch matrix.Figure 1.Flexural strength of thermoplastic starch foams containing different citric acid loading.…”
A simple preparation method was established for a low water-soluble citric acid crosslinking starch-based foam containing palm oil. The method was performed by pouring the boiling citric acid solution into the starch compound unlike the citric acid starch crosslinking by conventional solution casting. Thermo-physicochemical properties of the starch-based foams were examined. The I3300/I1149 intensity ratio of non-citric acid-containing foam was higher, suggesting greater amounts of the available -OH groups. The addition of citric acid into the starch matrix exhibited weaker thermal stability that was attributed to the lower thermal stability of the substituted ester bonds. The increment of citric acid concentration increased thermoplastic starch foams densities as well as their cell wall thickness. No differences in moisture absorption behavior were observed after soaking in water, the non-citric acid-filled foam exhibited dissolution and changed from its original shape upon drying. Experimental results showed a promising alternative methodology to prepare low water-soluble citric acid crosslinked starch-based foam to replace conventional solution casting.
“…32 Due to its low-cost production, abundance and thermoplastic behavior, starch has been widely applied in films for food packaging, with the properties of the films being directly influenced by the amylose and amylopectin content. [33][34][35][36][37][38][39] The use of native starch can produce mechanically fragile and hydrophilic films and, as an alternative to overcome this fragility, so-called "plasticizers", such as glycerol and sorbitol, are incorporated into the film formulation to provide an improvement in flexibility. Regarding hydrophilicity, crosslinking the film through chemical modification can be used to minimize the hydrophilic character.…”
The limited degradation of synthetic polymers used in food packaging when discarded in the environment is a major concern for society. Therefore, industry and academia have sought to develop biodegradable and eco-friendly materials for single-use in packaging. An interesting alternative for the food industry is biodegradable polymeric films, which is why different biopolymers have been used in the production of sustainable packaging. It is worth mentioning that the use of biodegradable polymers is one of the most successful innovations in the industry to address issues related to the environment. Among the available raw materials, starch extracted from different renewable sources is very promising for this purpose, due to its abundance, low-cost compared to other polymers and ability to produce non-toxic films. However, when used alone, pure starch has many limitations, which can be overcome by developing a mixture with other polymers (polymer blends), preferably from renewable and biodegradable sources, such as poly(lactic acid) (PLA). In this context, the absence of literature reviews evidencing the results of the application of films in foods led us to write this article, given the importance of polymer blends produced with different types of starch (cassava, corn, pea, potato, rice and wheat) and the PLA matrix. According to the results, it is clear that polymer blends based on PLA/Starch for food packaging are very promising, already being part of the industries solutions, aiming to minimize the large volume of plastic waste of petrochemical origin discarded in nature. Obviously, as with any technology, more research is needed to further improve the performance of the films, and while much research has made great strides, there are still limitations that prevent the commercialization of these materials.
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