RESUMEN

Mulch films were fabricated from polylactic acid (PLA) with cellulose nanocrystals (PNC) extracted from pineapple leaves. The PNC was modified by incorporating 4 wt% triethoxyvinylsilane (TEVS), designated as 4PNC, to enhance its interaction with PLA. The films incorporated varying concentrations of PNC (1, 2, 4, and 8 wt%). The results indicated that higher PNC concentrations increased the water vapor permeability (WVP) and biodegradability of the composite films, while reducing light transmission. Films containing 4PNC, particularly at 4 wt% (PLA/4PNC-4), exhibited an 11.18 % increase in elongation at break compared to neat PLA films. Moreover, these films showed reduced light transmission, correlating with decreased weed growth, reduced WVP, and enhanced barrier properties, indicative of improved soil moisture retention. Additionally, PLA films with 4PNC demonstrated greater thermal degradation stability than those with unmodified PNC, suggesting enhanced heat resistance. However, there was no significant difference in aerobic biodegradation between the PLA films with PNC and those with 4PNC. This study confirms that TEVS-modified cellulose significantly enhances the properties of bio-composite films, making them more suitable for mulch film applications.

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RESUMEN

Regenerated cellulose (RC) produced from waste pineapple leaves was used to develop a colorimetric sensor as a Cu-PAN sheet (RCS). Microcrystalline cellulose derived from dried pineapple leaves was combined with Cu-PAN, dissolved in NaOH and urea, and made into an RC sheet using Na2SO4 as a coagulant. The RCS was used as an H2S indicator at various H2S concentrations (0-50 ppm) and temperatures (5-25 °C). The RCS color changed from purple to New York pink when exposed to H2S. A colorimeter method was used to develop prediction curves with values of R2 > 0.95 for H2S concentrations at 5-25 °C. The physicochemical properties of fresh and spent RCS were characterized using various techniques (Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy/energy-dispersive X-ray spectroscopy, and thermogravimetric analysis). In addition, when stored at 5 and 25 °C for 90 days, the RCS had outstanding stability. The developed RCS could be applied to food packaging as an intelligent indicator of meat spoilage.

RESUMEN

The cinnamate functionalization of cellulose nanocrystals (Cin-CNCs) was investigated as a potential organic reinforcing and UV-shielding agent in polylactic acid (PLA) films. Acid hydrolysis was used to extract cellulose nanocrystals (CNCs) from pineapple leaves. Through esterification with cinnamoyl chloride, the cinnamate group was grafted onto the CNC surface and the resulting Cin-CNCs were incorporated in PLA films as reinforcing and UV-shielding agents. The PLA nanocomposite films were prepared using a solution-casting method and were tested for mechanical/thermal properties, gas permeability, and UV absorption. Importantly, the functionalization of cinnamate on CNCs substantially improved the dispersion of fillers on the PLA matrix. The PLA films containing 3 wt% Cin-CNCs exhibited high transparency and UV absorption in the visible region. On the other hand, PLA films filled with pristine CNCs did not exhibit any UV-shielding properties. The mechanical properties revealed that adding 3 wt% Cin-CNCs to PLA increased its tensile strength and Young's modulus by 70% and 37%, respectively, compared to neat PLA. In addition, the incorporation of Cin-CNCs substantially improved water vapor and oxygen permeability. At 3 wt% Cin-CNC addition, the water vapor and oxygen permeability of PLA films were reduced by 54% and 55%, respectively. This study demonstrated the great potential in utilizing Cin-CNCs as effective gas barriers, dispersible nanoparticles, and UV-absorbing, nano-reinforcing agents in PLA films.

RESUMEN

A thorough study was undertaken of the synthesis of natural rubber-silica treated with bis-(3-triethoxysilylpropyl) tetrasulfane (NR/TSi) vulcanized using electron beam irradiation (EB) and sulfur by varying the EB dose. The surface treatment of silica was confirmed using Fourier-transform infrared spectroscopy and scanning electron microscopy images. Composites were cast and vulcanized in film and latex forms compared with sulfur vulcanization. Investigation covered the mechanical properties, thermal stability, swelling resistance, and degradation under heat and humidity testing of the NR/TSi composites. It was found that the TSi had great dispersal in the NR matrix. TSi in NR matrix had a positive effect on mechanical properties, swelling in water and toluene, and thermal stability. Increasing the radiation intensity up to 250 kGy led to superior mechanical properties but for further increase in the radiation intensity, the tensile strength dropped. Degradation under thermal and humidity testing showed that the un-vulcanized composite had higher physical degradation than the vulcanized samples. Therefore, NR/TSi vulcanized using 200 kGy EB vulcanized in latex form had the greatest mechanical properties for various applications without producing any residual vulcanizing agent.

RESUMEN

Pineapple leaves were used as a natural fiber source to prepare various modified microcrystalline cellulose (MCC) samples as sorbents for H2S sorption. Pineapple leaf fibers were first extracted from pineapple leaves, followed by hydrolyzing to produce MCC before various modifications using primary amine (3-aminopropyltrimethoxysilane, APS), secondary amine (N-methyl-3-aminopropyltrimethoxysilane, MAPS), or tertiary amine (N,N-dimethyl-3-aminopropyltrimethoxysilane, DAPS). The characterization results proved that all the aminosilane groups were successfully grafted onto the MCC. In addition, the thermal stability and the porosity of the modified sorbents were enhanced relative to those of unmodified MCC. The H2S sorption studies of MCC modified with APS, MAPS, and DAPS at 0, 3, or 5%w/w showed that MCC-MAPS had better H2S sorption performance than MCC-APS and MCC-DAPS, respectively, when comparing the H2S sorption performance at the same loading level. The optimum H2S sorption performance of each aminosilane group was achieved from MCC-APS at 5%, MCC-MAPS at 3%, and MCC-DAPS at 5%. An additional study of H2S sorption of these three sorbents in the presence of CO2 showed that MCC-DAPS at 5% was the best sorbent for selective H2S removal. Our results indicated that MCC modified with the aminosilane groups, especially MAPS, were promising materials for H2S sorption, with potential application in gas separation.

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