Morphology and tensile properties of high-density polyethylene/natural rubber/thermoplastic tapioca starch blends: The effect of citric acid-modified tapioca starch

Improvement in Phase Compatibility and Mechanical Properties of Poly(L-lactide)-b-poly(ethylene glycol)-b-poly(L-lactide)/thermoplastic Starch Blends with Citric Acid

Flexible poly(L-lactide)-b-poly(ethylene glycol)-b-poly(L-lactide) block copolymer (PLLA-PEG-PLLA) bioplastic has been blended with low-cost thermoplastic starch (TPS) to prepare fully biodegradable bioplastics. However, the mechanical properties of PLLA-PEG-PLLA matrix decrease after the addition of TPS. In this work, citric acid (CA) was used as a compatibilizer to improve the phase compatibility and mechanical properties of PLLA-PEG-PLLA/TPS blends. TPS was first modified with CA (1.5 %wt, 3 %wt, and 4.5%wt) before melt blending with PLLA-PEG-PLLA. The PLLA-PEG-PLLA/modified TPS ratio was constant at 60/40 by weight. CA modification of TPS suppressed the crystallinity and enhanced the thermal stability of the PLLA-PEG-PLLA matrix, as determined through differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), respectively. The compatibility between the dispersed TPS and PLLA-PEG-PLLA phases was improved through modification of TPS with CA, as revealed by the smaller size of the co-continuous TPS phase from scanning electron microscopy (SEM) analysis. Increasing the hydrophilicity of the blends containing modified TPS confirmed the improvement in phase compatibility of the components. From the tensile test, the ultimate tensile strength, elongation at break, and Young's modulus of the blends increased with the CA content. In conclusion, CA showed a promising behavior in improving the phase compatibility and mechanical properties of PLLA-PEG-PLLA/TPS blends. These PLLA-PEG-PLLA/modified TPS blends have potential to be used as flexible bioplastic products.

A mechanically robust biodegradable bioplastic of citric acid modified plasticized yam starch with anthocyanin as a fish spoilage auto-detecting smart film

The current scenario of environmental pollution caused by non-biodegradable plastic and depleting non-renewable resources has called upon the need for biodegradable bioplastic production from renewable resources. Starch bioplastics production from underutilized sources is a viable option for packaging materials that are non-toxic, environmentally benign, and easily biodegradable under disposed conditions. Pristine bioplastic production results in some undesirable qualities and hence requires further modification in order to elevate its potential applicability in real-world scenarios. In this work, yam starch was extracted from a local variety of yams through an eco-friendly and energy-efficient process which was further utilized for bioplastic production. The produced virgin bioplastic was subjected to physical modification through the introduction of plasticizers such as glycerol, while citric acid (CA) was employed as modifier in order to produce the desired starch bioplastic film. The different compositions of starch bioplastics were analyzed for their mechanical properties and maximum tensile strength of 24.60 MPa was observed as the best possible experimental result. The biodegradability feature was further highlighted through soil burial test. Apart from their general function of preservation and protection, the produced bioplastic can be employed for pH-sensitive food spoilage detection through the minute introduction of plant-derived anthocyanin extract into it. The produced pH-sensitive bioplastic film showed distinct changes in color upon an extreme change in the pH value and hence has potential to be used as a smart food packaging material.

Physico-chemical properties and digestibility of native and citrate starches change in different ways by synchrotron radiation

The physico-chemical properties and digestibility of native and citrate cassava starches changed as a result of synchrotron radiation treatment. In this study, the native and citrate starch samples were exposed to radiation doses of 0.1, 0.4, 0.8 and 3.9 kGy. The granular morphology revealed that all samples were rupture and damage after radiation. As increasing radiation doses, the relative crystallinity as determined by WAXS and the ratio of 1047/1015 cm^-1 from FTIR result decreased while the degree of degradation and solubility increased for all samples. The swelling power of radiated native starches decreased with higher radiation doses indicating that the cross-linking of starch was induced by synchrotron radiation which was related to an increase in the resistant starch content. On the contrary, for radiated citrate samples, the FTIR peak at 1724 cm^-1 was observed. The ratio of 1724/2900 cm^-1 and total esterified citric acid did not change. The swelling and degree of di-esterification were reduced while the degree of mono-esterification increased with higher doses. It implied that the cross-linking by ester bonds was broken into mono-ester bonds. This work demonstrated that synchrotron radiation changed the physical and chemical properties of native and citrate starches in different ways.

Fabrication and characterization of one high-hygroscopicity liquid starch-based mulching materials for facilitating the growth of plant

One high-performance liquid starch-based mulching materials (LSMM) was successfully fabricated by grafting polyacrylic acid (PAA) onto starch then crosslinking with N,N'-methylene-bisacrylamide (MBA). The effects of the dosage of acrylic acid on the performances of LSMM film had been explored. The LSMM was characterized by FTIR, solid state ¹³C NMR, XRD and SEM. Their application performances by spraying the LSMM on the soil surface also had been discussed. The PAA grafted onto starch significantly improved the properties of LSMM film (tensile strength 20.89 MPa, elongation at break 59.19 %, water absorbency 68.58 g/g and solubility in water 4.5 %). The PAA broke the hydrogen bonds and reduced the crystallinity of starch molecule, which can form the compact structure in LSSM film. As a result, the LSMM showed excellent relative hygroscopicity, water retention, degradability (weight loss 72.61 %) and the effect of facilitating the growth and germination ratio (84.00 %) of lettuce.