This research investigated the production of biodegradable plastic films made from a blend of carrageenan and corn starch biopolymers. The procedure included producing bioplastic resin pellets using a single screw extrusion at a 110 degrees C temperature, followed by hot compression at a temperature of 160 degrees C to form a biodegradable plastic film. The project aimed to develop a continuous biodegradable plastic production method, particularly made from carrageenan, which is more adaptable for commercial-scale production. The carrageenan/corn starch films were prepared with various compositions, ranging from formulations dominated by carrageenan (56:14% w/w) to those dominated by corn starch (14:56% w/w), with the addition of a constant amount of glycerol (30% w/w) as a plasticizer. After the films were obtained, each of the samples was evaluated for their physico-mechanical properties, chemical structure, water sensitivity, and soil biodegradability. In general, an increase in corn starch content within the film matrix led to an enhancement of the overall properties of the resulting film. The film with the highest corn starch content exhibited tensile strength and elongation at break values that were 49% and 163% higher, respectively, compared to the film with the lowest corn starch content. Additionally, these samples demonstrated improved thermal stability, with a 12% increase in the thermal decomposition temperature, and enhanced barrier properties, as evidenced by a 6% reduction in water vapor permeability and a 72% decrease in water uptake. This is mainly due to the inherent molecular structure of corn starch, particularly due to its long straight-glucose chains. On the other hand, carrageenan increased the biodegradability rate of the films. These findings demonstrate the potential of carrageenan/corn starch blends as promising candidates for future packaging materials.

Seaweeds are a rich source of various bioactive compounds and metabolites. In this study, sulfated polysaccharide, kappa-carrageenan has been isolated from red algae, Hypnea valentiae, and developed biodegradable film with the addition of plasticizers, sorbitol and polyethylene glycol (PEG 4000) at varying concentrations of carrageenan (1%, 5% and 7% Carr). The biodegradable film exhibited excellent mechanical properties with increasing carrageenan concentration. The 5% Carr film showed improved water barrier properties, high water contact angle (hydrophobicity), high tensile strength (11.38 MPa) and elongation at break (23.27%) which imparts rigidity and flexibility to the film. The results of FTIR and SEM images revealed that the plasticizers and polysaccharides have been blended properly. Since seaweeds are natural antioxidants the kappa-carrageenan based biodegradable films displayed strong radical scavenging activity. The 7% Carr film exhibited 86% of radical scavenging activity in ABTS assay and 5% Carr showed 80% of scavenging activity. The biodegradable films displayed efficient antibacterial activity against gram-negative bacteria, E. coli and gram-positive bacteria, B. subtilis. The developed films exhibited excellent biodegradability, the films samples degraded completely within 84 days of soil burial. The kappa-carrageenan based biodegradable film (5% Carr) from red algae, H. valentiae better serves as a versatile food packaging material.

The employment of novel biopolymers offers geotechnical engineers a diverse range of materials to choose from, depending on the specific requirements of different projects. Regarding the promotion of environmentally friendly materials in the construction industry, this study introduces carrageenan as a novel biopolymer for soil improvement. The research also includes a comparative study of carrageenan's performance with xanthan which is the most commonly used biopolymer in geotechnical engineering. Unconfined compressive tests (UCS) were conducted to evaluate the performance of biopolymer-treated soil samples over a variety of effective parameters including biopolymer content, moisture content, curing time, soil particle size, and durability under wet-dry cycles. In order to explore the soil size effect, kaolinite silt and sand were combined in various proportions and treated with different biopolymer ratios to enhance strength development. The optimal mix of each biopolymer-treated soil was then exposed to five cycles of wetting and drying. Carrageenan improved the compressive strength of untreated soils in all cases, for example 3.4 times for 0.5% (wb/ws) of biopolymer. In higher proportions of kaolinite, carrageenan performed considerably better than xanthan gum in terms of compressive and shear strength. In addition, with an emphasis on confining pressures, static triaxial experiments were conducted to examine the effectiveness of carrageenan, by which it was shown that carrageenan out-performs xanthan in terms of shear strength especially in the fine-grained soil. The mechanism and chemical interaction behind the significant performance of carrageenan in binding soil grains, increasing mechanical strength and improving durability of the soil was also studied through FTIR analysis and scanning electron microscopy (SEM) images. It can be concluded that carrageenan can be considered as a sustainable alternative to conventional materials such as cement and lime.