Antioxidant packaging development and optimization using agroindustrial wastes

The increasing use of non-biodegradable materials and the difficulty in recycling most of the available packaging have been pushing the development of biodegradable packaging. In this study, the potential uses of agroindustrial wastes to produce biodegradable films with antioxidant capacity were investigated. Starch films were produced by casting method using bran from jaboticaba peel, mango peel, and broccoli stalk. The influence of the concentration or type of bran in the properties of the films was evaluated through a central composite design. The results were analyzed by response surface and desirability function. Except for elongation and water solubility, the fitted equations were predictive in all studied properties. The films prepared from a higher concentration of mango peel exhibited better antioxidant capacity, while the broccoli stalk had no significant effect on antioxidant properties. The optimal formulation of the film (2.8% of jaboticaba peel and 20.0% of mango peel) and their predicted response variables (0.8 MPa for tensile strength, 40.0 MPa for Young's modulus, 4.5 mg/ml for IC₅₀, and 41.6% for inhibition percentage) were defined according to the results. The optimization was satisfactory and the film presented high antioxidant capacity and moderate mechanical properties, proving to be an alternative to replace plastic packaging.     

Adhesion study of high reflectivity water-based coatings

A waterborne polyurethane coating with reflectivity higher than 95% in the visible wavelength range of 380–750 nm has been formulated. The impact of pigment concentration and carboxyl functional dispersing agent percentage on the adhesion of this waterborne polyurethane-based coating to an aluminum substrate is characterized at various pigment weight fractions by peel strength using modified ASTM D 1876-93. The formulated coating was also examined by SEM, UV/vis spectrophotometer with integrating sphere, and ATR–FTIR. Results indicate that the reflectivity of the coating increases with pigment volume concentration while the peel strength decreases. At high pigment-to-binder ratios a change in failure mode from adhesive to cohesive was observed. Further experiments indicate that adhesion increased at high pigment-to-binder ratios due to the presence of carboxyl functional groups of the dispersing agent. The increase in adhesion was identified for the first time and attributed to the interaction of the carboxyl functional groups in the dispersing agent with the aluminum surface.     

A rapid estimation of pigment content in virgin olive oils by a solvent-free method

In this work, a fast method was proposed for estimating the virgin olive oils (VOOs) carotenoids and chlorophylls concentration using color measurement. The pigment content by conventional spectrophotometry method and CIELAB color (L*, a*, and b*) at different degree of sample thickness (from 5 to 50 mm) of one hundred VOOs were measured. Oil carotenoids and chlorophylls content were correlated with the color parameters for the different oil thickness studied to design the prediction models of the new method. The best regression coefficients (R²) were obtained for multiple linear regression model using the three independent variables (L*, a*, and b*) together measured at 5 mm of oil thickness. The R² were 0.9679, 0.9515, and 0.9644 for predicting carotenoids, chlorophylls, and total pigments, respectively. External validation of these prediction models was satisfactory (relative error < 0.1). Therefore, this new solvent-free colorimetric method is a useful method for determination of carotenoids and chlorophylls content in VOOs. Practical applications: The simple colorimetric method developed in this study offers a fast and accurate alternative to current methods published in the literature to estimate the pigment content in VOOs. It is a rapid (less than 1 min) and cheap method, with the advantage of ease of operation, no sample pretreatment and solvent-free, thus environmentally friendly. This methodology can potentially be used by trained “nonprofessional analytical skilled” people in small laboratories or olive oil mills with limited technical facilities. Therefore, the technique is highly plausible as an alternative to determine the pigment content in VOOs. Finally, future works with this methodology could be carried out to online control of VOOs pigments content in the oil extraction process.     

Effect of the milling process on the properties of CoFe2O4 pigment

In this study, CoFe₂O₄ pigments were synthesised using both co-precipitation and conventional ceramic methods. Pigment particles prepared using the conventional ceramic method were subsequently milled to submicron size. The effects of the solvent, dispersant and milling type in the milling process were investigated. This study showed that planetary milling in a diethylene glycol (DEG) medium with sodium tripolyphosphate (STPP) was an effective method for producing submicron-sized pigment powders from pigments synthesised using the conventional method. With this method, submicron-sized pigment particles (approximately 190 nm) were obtained after milling for 4 h. Planetary milling was more efficient in reducing particle size compared to attrition milling. Co-precipitated pigment had a more intense black colour, due to the nanoscale particle size (<100 nm). However, conventional ceramic pigments also had an adequately intense black colour that increased after milling compared to unmilled conventional pigments. When considering production of industrial scale submicron-sized pigments, the milling of these pigments to submicron size can be a good alternative method for the production of ink colourants.     

Properties of UV-cured pigment prints on textile fabric

This paper studies and evaluates the UV-curing of pigment prints on textile fabric using a prototype UV scanner. A printing paste comprising synthetic thickener, emulgator, binder, pigment dispersion and photoinitiator was applied using a flat screen printing technique onto the cotton fabric, then dried and exposed to heat or UV-radiation under a mercury vapour lamp (200 W cm⁻²). The characteristics of cured prints such as paste add-on, colour properties, colour fastness to washing and dry/wet rubbing were evaluated, together with fabric stiffness. The effects of UV-curing were evaluated by Attenuated Total Reflectance Fourier transform infrared spectroscopy (ATR-FTIR). The properties of the UV-cured pigment prints were compared with those of the thermal cured prints. Analyses of the obtained results helped to define the optimum composition of the photo reactive pigment paste, and the UV-curing conditions under which satisfactory results were obtained, comparable with those from the thermal curing method.     

橘皮色素提取工艺的研究进展

橘皮色素是一类重要的天然色素,具有多种生物活性,可替代合成色素而应用广泛.本文介绍了橘皮色素的理化性质及其生物活性,详细综述了超声波辅助法、微波辅助提取法、超临界CO2萃取法、硫酸铵预处理-乙醇提取法及浸提法等橘皮色素提取工艺的研究进展,重点讨论了各种提取工艺法的研究热点及目前存在的问题,并展望了橘皮色素提取工艺的发展前景.     

Solvothermal preparation and gas sensing properties of hierarchical pore structure SnO2 produced using grapefruit peel as a bio-template

Hierarchical pore structure nano-sized SnO₂ was synthesized using a solvothermal method with SnCl₄ as the raw material and grapefruit peel as the bio-template. The products were characterized by powder X-ray diffraction, high resolution scanning electron microscopy, transmission electron microscopy and nitrogen adsorption/desorption measurements. The results show that the SnO₂ prepared from the grapefruit peel bio-template consists of many large size (5–20 µm) interconnected pores with a honeycomb structure and nanosized pores (9.46 nm) on the walls of the large pores. The as-prepared SnO₂ presented a high specific surface area of 42.98 m²/g and the average crystallite size was about 10±0.5 nm. The gas sensing performance of the prepared material toward several volatile organic compounds was investigated. The results show that the hierarchical pore structure nano-sized SnO₂ was highly sensitive and selective to n-butanol, indicating that this material may be a promising candidate for future development as a n-butanol gas sensor.     

Preparation of high near-infrared reflectance mica/(Ni,Sb)-co-doped rutile yellow composite pigment via mechanochemical pretreatment and sintering

Mica/(Ni, Sb)-co-doped rutile yellow composite pigment with a high near-infrared reflectance was prepared via mechanochemical pretreatment and subsequent sintering. (Ni, Sb)-co-doped rutile yellow pigment was synthesized by a solid-phase method in the presence of sodium fluoride (NaF) as a mineralizer, and mica was peeled by ultrafine grinding. The pigment, mica and mica/pigment composite were characterized by X-ray diffraction, laser diffraction particle size analysis, nitrogen gas adsorption method, scanning electron microscopy, energy dispersive spectroscopy, ultraviolet–visible–near-infrared spectroscopy, CIEL*a*b* color scales, and infrared irradiation image, respectively. The results show that the temperature of synthesizing a pure rutile pigment in solid-phase reaction is reduced by 100°C due to the addition of mineralizer NaF. (Ni, Sb)-co-doped rutile pigment has better color rendering performance and near-infrared (NIR) reflectance. Ultrafine grinding produces the finer flatty mica particles with fresh reflective surfaces, thus improving NIR reflectance of peeled mica. In mica/pigment composite prepared via mechanochemical pretreatment and subsequent sintering, peeled mica has a synergistic effect on (Ni, Sb)-co-doped rutile pigment particles to further scatter near-infrared radiation through the multiple layer reflections, leading to a better heat insulation. The high near-infrared reflectance of composite pigment increases to 97.72%, and the b* value of the pigment synthesized with 1 wt% NaF is 37.77. For the irradiation infrared lamp, the surface temperature of aluminum plate coated with mica/(Ni, Sb)-co-doped rutile yellow composite pigment is 40.1 ± 0.2°C, which is lower than that of aluminum plate uncoated determined by thermal camera and thermocouple. When aluminum plate coated with mica/(Ni, Sb)-co-doped rutile yellow composite pigment is under sunshine, its surface temperature is 38.6 ± 0.2°C. In addition, the mechanism of preparing the composite pigment via mechanochemical pretreatment and subsequent sintering and the multiple structure reflection effect on peeled mica surface coated with (Ni, Sb)-co-doped rutile yellow pigment particles were also discussed.     

Adsorption of Reactive Blue 114 dye by using a new adsorbent: Pomelo peel

This paper describes the removal of Reactive Blue 114 dye from aqueous solutions by using pomelo (Citrus grandis) peel. Pomelo peel can be described as a new, low cost, abundantly available adsorbent. The optimum adsorbent mass, dye concentration, contact time and pH were determined in this study. The parameters of Langmuir, Freundlich and Temkin adsorption isotherms were also obtained using concentrations of the dyes ranging from 1.0 to 200 mg/L. Maximum adsorption capacity was obtained as 16 mg/g at pH 2 and 303 K solution temperature. The adsorption process was observed to be reaching equilibrium after about 90 min.     

Microsphere pressure sensitive adhesives—acrylic polymer/montmorillonite clay nanocomposite materials

In this study, the synthesis and characterization of acrylic polymer/montmorillonite (MMT) clay nanocomposite pressure sensitive adhesives (PSA) are presented. Different types and amounts of modified and unmodified montmorillonite clays were dispersed in ethyl acrylate (EA)/2-ethylhexyl acrylate (2-EHA) monomer mixture, which was then polymerized using a suspension polymerization technique. Polymerization was monitored in-line using attenuated total reflectance-fourier transform infrared (ATR-FTIR) spectroscopy. The adhesion properties of the synthesized nanocomposite materials were determined using standard measurements of tack, peel and shear strength. Viscoelastic properties of dried adhesive films were analyzed using dynamic mechanical analysis (DMA). The results showed that the kinetics of suspension polymerization was independent of the addition of MMT clays. On the other hand, adhesive properties were strongly influenced by the type and the amount of MMT clay added. While peel strength and tack gradually decreased with higher amount of modified MMT clay, a substantial increase in shear strength was determined with a maximal value at 1 wt% of added MMT clay. Moderate influence on tack, peel and shear strength was observed when the unmodified type of MMT clay was used. DMA analysis showed an increase in storage modulus (G′) for adhesives synthesized with MMT clay addition, but no significant differences were determined between particular types of MMT clays. A decrease in tan δ value for adhesives with 1 wt% of added MMT clay was observed, which also concurs with higher shear strength and implies to the improved cohesion of adhesive.     

Development of a yellow ceramic pigment based on silver nanoparticles

In this study a yellow pigment was obtained for third-fire ceramic decorations, based on silver nanoparticles synthesised by the method of chemical reduction in aqueous phase, using silver nitrate and polyvinylpyrrolidone as raw materials. Monitoring of the nanoparticle synthesis reaction by UV–vis spectroscopy allowed optimum operating conditions to be defined in preparing these particles for use as chromophores. Under these conditions, a stable suspension of Ag nanoparticles, which were well dispersed and had an average diameter of 20–30 nm, was obtained. Polyvinyl alcohol and tetraethyl orthosilicate were then added to the nanoparticle suspension to obtain the pigment precursor. The pigment precursor was directly applied on to fired glazed ceramic tile. Subsequent thermal treatment at moderate temperature (700 °C) yielded a layer less than one micron thick, which generated an intense yellow colour.     

Colored films produced by electron beam deposition from nanometric TiO2 and Al2O3 pigment powders obtained by modified polymeric precursor method

Synthesis and the characterization of TiO₂:5%Co (green), TiO₃:5%Fe (brown-reddish), TiO₂:2%Cr (brown), Al₂O₃:5%Co (blue), Al₂O₃:5%Fe (brown-reddish) and Al₂O₃:2%Cr (light green) nanometric pigment powders using polymeric precursor (modified Pechini's method) is reported. Colored thick films were deposited on amorphous quartz substrates by electron beam physical vapor deposition (EB-PVD) using pellets of the pigment powders as target. The evaporation process was carried out in vacuum of 4 × 10⁻⁶ Torr and the amorphous quartz substrates were kept at 350 °C during deposition. The TiO₂-based pigment powders presented crystalline anatase phase and the Al₂O₃-based pigment powders showed corundum phase, investigated by X-ray diffraction (XRD). The average particle size of the pigment powders was about 20 nm, measured by scanning electron microscopy with field emission gun (SEM-FEG). Diffuse reflectance spectra and colorimetric coordinates L¹, a¹, b¹ using the CIE-L¹a¹b¹ method are shown for the pigment powders, in the 350–750 nm range. The colored thick films were characterized by transmittance (UV–Vis) and atomic force microscopy (AFM). The average film roughness was ∼5.5 nm and the average grain size obtained in the films was around 75 nm. Films with thickness from 400 nm to 690 nm were obtained, measured by talystep profiler. Transmission spectra envelop method has been used to obtain refractive index and thickness of the Al₂O₃ colored thick films.     

Interfacial Energy and Adhesion between Acrylic Pressure Sensitive Adhesives and Release Coatings

The interfacial adhesive behavior between acrylic pressure sensitive adhesive-like networks (PSA-LNs) and poly(vinyl N-alkyl carbamate) release coatings was studied using a contact mechanical method and peel tests. Surface energy and interfacial energy were directly measured in JKR tests using a novel sample construction. The surface energy of the poly(vinyl N-alkyl carbamates) was found to be around 20 mJ/m². Interfacial energies between PSA-LNs and the release coatings were found to be quite high – between 7 and 24 mJ/m². Changes in adhesion dynamics were governed by acid-base interactions between the carbamate in the release coating and the acid groups in the PSA-LN. The length of the alkyl chain in the release coating moderated this effect. We also found a correlation between fundamental adhesion energy and peel strength. Examination of this phenomenon provides a basis for understanding the poor storage stability of PSA tapes made using alkyl carbamates and acid-containing PSAs.     

New bilayer-coated microbead system for controlled release of 5-aminosalicylic acid

A new bilayer-coated microbeads for oral delivery of 5-aminosalicylic acid (5-ASA) were prepared from naturally occurring polysaccharides via emulsification method. 5-ASA was successfully encapsulated in chitosan–λ-carrageenan-coated alginate microbeads. The morphology and sizes of microparticles were studied using optical microscopy and dynamic light scattering. Drug release profiles were followed using high-performance liquid chromatography (HPLC) with spectrophotometric detection. The effect of chitosan thin layer and chitosan–λ-carrageenan bilayer on the drug release was studied at pH values simulating these characteristic for stomach (pH = 1.2) and intestine (pH = 7.4). Chitosan layer slightly increased 5-ASA release at pH = 1.2, whereas double-layer external coating decreased the release rates. Due to the bilayer properties, the micro-carriers were additionally protected against acidic conditions of the stomach and drug release in the intestine could be better controlled.     

Emulsion-based pressure sensitive adhesives from conjugated linoleic acid/styrene/butyl acrylate terpolymers

Free radical emulsion terpolymerizations of conjugated linoleic acid (CLA), styrene (Sty), and butyl acrylate (BA) were performed at 80 °C. Terpolymers were characterized for composition, conversion, molecular weight and glass transition temperature, latexes were characterized for viscosity and particle size while adhesives were characterized for tack, peel strength, shear strength, storage modulus, loss modulus and tan delta. One impurity commonly found in CLA, oleic acid, was shown to influence the reaction kinetics significantly. Adhesive performance was tuned using divinylbenzene (DVB) crosslinker to keep the terpolymer molecular weight in a desired range. By using a constrained mixture design, the influence of terpolymer composition, chain transfer agent (CTA) concentration, DVB concentration, molecular weights, viscosity and particle size on tack, peel strength and shear strength was investigated. The final forms of the resulting empirical models allowed the creation of 3D response surfaces for pressure sensitive adhesive (PSA) performance optimization.     

Multifunctional superhydrophobic and cool coating surfaces of the blue ceramic nanopigments based on the heulandite zeolite

The heulandite zeolite was successfully used as the host structure for a new Co-based blue colorant ceramic pigment. The method was the ion exchange of Co and Zn cations with the host structure, which induced a heat-collapsed structure followed by a recrystallization process at 1200 °C/h. The synthesized blue pigment was coated by spraying on the surface of pre-sintered ceramic tile followed by firing at 980 °C/10min. For modification of its surface, ZnO nanoparticles (NPs) and commercial antifouling were used. The blue powder pigment and ceramic coated surface were characterized with XRD, Rietveld refinement, TGA-DTA, FE-SEM-EDS, BET-BJH, UV-VIS-NIR spectroscopy, CIEL*a*b* color measurement, water contact angle (WCA), and roughness analysis. The single-crystal Co-willemite has been achieved (b* = ?45 and a* = ?0.5). The blue pigment coated on the surface after being modified with ZnO NPs and antifouling revealed a superhydrophobic surface with WCA = 153.7°. Due to this, a low water sliding angle of less than 5° have achieved. The surface showed high thermal stability and adherence. The superhydrophobicity was mainly due to the micro-nanopatterned lotus leaf-like crystal structure and roughness of 3.15 μm on the surface. The surface showed 64% total reflectance from 700 to 2500 nm (UV and NIR), which resulted in a perfect candidate for a cool coating.     

The effect of benzimidazole and zinc acetylacetonate mixture on cathodic disbonding of epoxy coated mild steel

Electrochemical behavior of mild steel in the presence of zinc acetylacetonate (Zn(acac)₂) and benzimidazole (BIMIDA) was evaluated by electrochemical impedance spectroscopy (EIS) in 3.5% NaCl solution and compared to zinc phosphate (ZP) pigment and zinc potassium chromate (ZPC) pigment extracts. Results showed superior performance of Zn(acac)₂ and BIMIDA mixture (ZBM) compared to ZP pigment, while it introduced inferior inhibitive action compared to ZPC pigment. The epoxy coatings were formulated with ZBM as anticorrosive additive, ZP and ZPC pigments. The disbonding rate of coated steel follows the order: Blank > ZP > ZBM > ZPC. EIS results showed a complex film could be formed at the hole area for the coatings formulated with ZP, ZBM and ZPC. It is concluded that the stronger the complex film on the surface, the lesser the cathodic disbonding rate would be.     

Dilute acid hydrolysis of lignocellulosic biomass

The overall aim of this work was to establish the optimum conditions for acid hydrolysis of hemicellulosic biomass in the form of potato peel. The hydrolysis reaction was undertaken in a 1l high pressure pilot batch reactor using dilute phosphoric acid. Analysis of the decomposition rate of hemicellulosic biomass (namely Cellulose, Hemicellulose and lignin) was undertaken using HPLC of the reaction products namely, 5 and 6 carbon sugars. Process parameters investigated included, reactor temperature (from 135 °C to 200 °C) and acid concentration (from 2.5% (w/w) to 10% (w/w)). Analysis of the reactor products indicated that high conversion of cellulose to glucose was apparent although arabinose conversion was quite low due to thermally un-stability. However, an overall sugar yield is 82.5% was achieved under optimum conditions. This optimum yield was obtained at 135 °C and 10% (w/w) acid concentration. 55.2 g sugar/100 g dry potato peel is produced after a time of 8 min. The work indicates that the use of potato peel may be a feasible option as a feed material for the production of sugars for biofuel synthesis, due its low cost and high sugar yields.     

Impact of synthesis method on the properties of near-infrared region-reflective SrSn0.9Mn0.1O3 brown pigment

Brown near-infrared region (NIR) reflective pigment of SrSn_0.9Mn_0.1O₃ was prepared using four different methods: the classical ceramic method, both wet and dry mechanochemical activation processes and the precipitation method. The pigments were characterised in terms of colour properties, NIR reflectivity, phase composition, particle size distribution and particle morphology. The prepared powders were applied to the organic matrix in mass tone, and their resulting colour hues shifted from copper brown via chocolate brown to dark brown. The NIR solar reflectance was calculated in the wavelength interval of 700–1650 nm following the ASTM 173-03 standard and their values of powder form were 25%–44%. The colour hue and NIR solar reflectance were dependent on the calcination temperature and the preparation method. The optimal condition for the preparation of the most NIR-reflective saturated brown pigment is the precipitation method and a temperature of 1050 °C (R_solar = 42%; C_{powder form} = 18.4), with an interesting matchstick shape of particles.     

Release Mechanisms for Pressure Sensitive Adhesive Tape on Silicone-Coated Glass

Regarding the function of the silicone release agent, the following two mechanisms, that is, the low energy surface of a cross-linked methyl hydrogen polysiloxane (MHPS) resin and the separation of a non-cross-linkable dimethyl polysiloxane (DMPS) oil itself have been compared. The 180° peel strength of the glass plate/silicone release agent/pressure sensitive adhesive (PSA) tape laminates decreased in the following order: un-coated > MHPS-coated > DMPS-coated glasses. ATR, ESCA and SEM observations of the PSA and glass surfaces after the peel test showed that no MHPS transferred from the glass surface to the PSA but a part of the DMPS transferred. From these results, it was concluded that, for decreasing peel strength, the separation of silicone oil (DMPS) itself is more effective than the low energy surface of the silicone resin (cross-linked MHPS).