Addition of Al(OH)3 versus AlO(OH) nanoparticles on the optical, thermo-mechanical and heat/oxygen transmission properties of microfibrillated cellulose films

Differently structured aluminum (tri/mono) hydroxide (Al(OH)3 /AlO(OH)) nanoparticles were prepared and used as thermal-management additives to microfibrillated cellulose (MFC), cast-dried in thin-layer films. Both particles increased the thermal stability of the MFC film, yielding 20–23% residue at 600 °C, and up to 57% lowered enthalpy (to 5.5–7.5 kJ/g) at 0.15 wt% of loading, while transforming to alumina (Al2O3). However, the film containing 40 nm large Al(OH)3 particles decomposed in a one-step process, and released up to 20% more energy between 300 and 400 °C as compared to the films prepared from smaller (21 nm) and meta-stable AlO(OH), which decomposed gradually with an exothermic peak shifted to 480 °C. The latter resulted in a highly flexible, optically transparent (95%), and mechanically stronger (5.7 GPa) film with a much lower specific heat capacity (0.31–0.28 J/gK compared to 0.68–0.89 J/gK for MFC-Al(OH)3 and 0.87–1.26 for MFC films), which rendered it as an effective heat-dissipating material to be used in flexible opto-electronics. Low oxygen permeability (2192.8 cm3/m2day) and a hydrophobic surface (> 60°) also rendered such a film useful in ecologically-benign and thermosensitive packaging.

Addition of Al(OH)3 vs. AlO(OH) nanoparticles on the optical, thermo-mechanical and heat/oxygen transmission properties of microfibrillated cellulose films

Differently structured aluminum (tri/mono) hydroxide (Al(OH)3 / AlO(OH)) nanoparticles were prepared and used as thermal-management additives to microfibrillated cellulose (MFC), cast-dried in thin-layer films. Both particles increased the thermal stability of the MFC film, yielding 20–23% residue at 600 °C, and up to 57% lowered enthalpy (to 5.5–7.5 kJ/g) at 0.15 wt% of loading, while transforming to Al2O3. However, the film containing 40 nm large Al(OH)3 particles decomposed in a one-step process, and released up to 20 % more energy between 300–400°C as compared to the films prepared from smaller (21 nm) and meta-stable AlO(OH), which decomposed gradually with an exothermic peak shifted to 480 °C. The latter resulted in a highly flexible, optically transparent (95%), and mechanically stronger (5.7 GPa) film with a much lower specific heat capacity (0.31 − 0.28 J/gK compared to 0.68–0.89 J/gK for MFC-Al(OH)3 and 0.87–1.26 for MFC films), which render it as an effective heat-dissipating material to be used in flexible opto-electronics. Low oxygen permeability (2192.8 cm3/m2day) and a hydrophobic surface (>60°) rendered such a film also useful in ecologically-benign and thermosensitive packaging.

Characterization of the Oxygen Transmission Rate of New-Ancient Natural Materials for Wine Maturation Containers

Today, there is a trend in enology promoting a return to the use of old natural materials for the manufacture of storage and maturation wine tanks. One of the most sought-after characteristics of these materials is their permeability to oxygen from the atmosphere to improve wines without this being a harmful process. The reference performance in wine aging is, without doubt, the oak barrel for its ability to oxidize wines in a controlled way, thus improving them. It would be possible to mature wines in containers in which the use of wood is not obligatory, as opposed to aging in oak barrels or foudres. This work presents the results of oxygen permeation analysis under test conditions typical of a tank containing wine, using materials, such as concrete and granite. The oxygen permeability of the materials tested was very diverse, typical of natural materials. The results showed that earthenware presents an excessive permeability, not only to atmospheric oxygen, but also to liquids and needs treatment before being used in liquid containers. Claystone and concrete can be impermeable to liquids, but maintain permeability to atmospheric oxygen—making them candidates for use in permeable tanks for wine maturation. Finally, granite has some very interesting characteristics, though thickness control is required when calculating the desired oxygen transmission rate.

Aged layered double hydroxide nanosheet–polyvinyl alcohol dispersions for enhanced gas barrier coating performance

The oxygen transmission rate of a PET coated film showed a 37-fold decrease using a dispersion of LDH nanosheets in polyvinyl alcohol that was prior aged for 8 weeks compared to the film coated with the equivalent freshly prepared LDH/PVA dispersion.

Effects of flexing, optical density, and lamination on barrier and mechanical properties of metallized films and aluminum foil centered laminates prepared with polyethylene terephthalate and linear low density polyethylene

Flex barrier and optical density (OD) are two unique properties for metallized films and aluminum foil. This study investigated the effect of flexing on barrier properties of a laminate comprising metallized films and aluminum foil, as well as OD and adhesive lamination process on the overall multilayer laminate performance. Three (3) barrier layers, namely aluminum foil, metallized polyethylene terephthalate (met OPET) film with a high OD, and standard metallized PET film(met OPET), were laminated with the same printing layer OPET and sealing layer linear low density polyethylene (LLDPE), into OPET/adhesive/foil/adhesive/LLDPE and OPET/adhesive/met OPET/adhesive/LLDPE structures. The oxygen transmission rate (OTR) and water vapor transmission rate (WVTR) were measured before and after flexing. The aluminum foil centered laminate had an excellent oxygen barrier after the 20-cycle flexing test and failed to retain its oxygen barrier after the 270-cycle flexing. Compared to the aluminum foil centered laminate, the metallized film centered laminates were less affected by the flexing on the oxygen barrier. For all laminates, the water vapor barrier was less severely affected by flexing than the oxygen barrier. This study suggests that the ASTMF392 Gelbo D (20- cycle flexing) can determine if aluminum foil and metallized film centered laminates are resistant to flex-formed pinhole failures. A higher OD, a thicker film thickness and lamination process improved laminate’s actual barrier, resulting in lower measured transmission rates versus that predicted using Henry's solubility law and Fick's diffusion law. The laminate’s water vapor transmission rate is 55–74% lower than predicted. The oxygen transmission rate is 15–31% lower than predicted.

Enhancing the Oxygen Barrier Properties of Nanocellulose at High Humidity: Numerical and Experimental Assessment

Films formed from cellulose nanofibrils (CNFs) are known to be good barrier materials against oxygen, but they lose this feature once placed in humid conditions. To tackle this issue, we applied an optimized pressing condition under elevated temperature to increase the films’ density and improve their barrier performance. Furthermore, a water barrier coating was employed on the surfaces to control the moisture uptake at high relative humidity (RH). Neat self-standing films of CNF with the basis weight of 70 g/m2 were made through a filtration technique and pressed for 1 hour at 130 °C. The resulting nanostructures were covered on both sides using a water-borne barrier layer. Hot-pressing resulted in a significant reduction in oxygen transmission rate (OTR) values, from 516.7 to 3.6 (cm3/(m2·day)) and to some degree, helped preserve the reduced oxygen transmission at high relative humidity. Introducing 35 g/m2 of latex coating layer on both sides limited the films’ swelling at 90% RH for about 4 h and maintained the OTR at the same level. A finite element model was used to predict the dynamic uptake of water into the systems. The model was found to over-predict the rate of water uptake for uncoated samples but gave the correct order of magnitude results for samples that were coated. The obtained data confirmed the positive effect of hot-pressing combined with coating to produce a film with low oxygen transmission rate and potential to maintain its oxygen barrier feature at high relative humidity.

Artificial Intelligence Methods for Constructing Wine Barrels with a Controlled Oxygen Transmission Rate

Oxygen is an important factor in the wine aging process, and the oxygen transmission rate (OTR) is the parameter of the wood that reflects its oxygen permeation. OTR has not been considered in the cooperage industry yet; however, recent studies proposed a nondestructive method for estimating the OTR of barrel staves, but an efficient method to combine these staves to build barrels with a desired OTR is needed to implement it in the industry. This article proposes artificial intelligence methods for selecting staves for the construction of barrel heads or bodies with a desired target OTR. Genetic algorithms were used to implement these methods in consideration of the known OTR of the staves and the geometry of the wine barrels. The proposed methods were evaluated in several scenarios: homogenizing the OTR of the actual constructed barrels, constructing low-OTR and high-OTR barrels based on a preclassification of the staves and implementing the proposed method in real cooperage conditions. The results of these experiments suggest the suitability of the proposed methods for their implementation in a cooperage in order to build controlled OTR barrels.

Equibiaxially stretchable colorless and transparent polyimides for flexible display substrates

Abstract4,4′-(4,4′-isopropylidenediphenoxy)bis(phthalic anhydride) (BPADA) was reacted with three structurally different diamines to produce poly(amic acid)s, which were then imidized to produce colorless and transparent polyimide (CPI) films through stepwise thermal cyclization. The three amines used to synthesize CPI based on BPADA are: bis(3-aminophenyl)sulfone (APS), p-xylyenediamine (p-XDA), and bis[4-(3-aminophenoxy)-phenyl] sulfone (m-BAPS). The obtained CPI films were almost colorless and exhibited excellent optical transparencies. The solubility of the CPI films in various solvents was investigated, and all the CPI films were found to be soluble in common solvents such as chloroform, dichloromethane, N,N’-dimethyl acetamide, and pyridine. The thermo-optical properties and oxygen transmission rates (O2TRs) of the CPI films were examined for various biaxial stretching ratios in the range of 100–150%, and their properties were compared. When the stretching ratio changed from 100 to 150%, the glass transition temperature and yellow index did not show any significant change; however, the O2TR decreased for all CPI films.