Applied Mechanics and Materials Vol. 469

Abstract: With the development of estate and decoration industry, decorative paper become more and more popular, people's needs and requirements are also increasing. However, compared with imported decorative base paper, domestic decorative base paper have a lot of quality problems. In order to improve the performance of domestic decorative paper, surface sizing was used to improve the printing performance and final product quality of domestic decorative base paper in this study. Starch and styrene-acrylic emulsion (SAE) were used as the surface sizing agents for the surface treatment of decorative base paper by the German SUMET coating machine in this paper. Under the conditions of sizing roll pressure of 250N, sizing speed 9m/min, drying temperature and time of 100°C and 70s respective, the effects of metering roller type (No.40 and No.30) and different ratios of starch and SAE ratio (10:1, 15:1, 20:1, 25:1 and 30:1) on the decorative base paper printing performance were investigated in this paper. The optimal sizing conditions and formulation for decorative base paper were as follows: roll pressure 250N, sizing speed 9m/min, drying temperature and time of 100°C and 70s respective, No.30 metering roll, the ration of starch and SAE 20:1. Under this conditions, printing runnability of decorative base paper such as the tensile strength, smoothness were increase greatly and the pH value reached the national standard, the printability such as the color density, tone reproduction range were improved.

Abstract: In order to achieve food packaging sterilization rapidly and improve packaging sterilization property, the nanoTiO₂ photocatalyst loaded on wooden activated carbon fibers (WACFs) is prepared by sol-gel method. The effects of loading processes on loading rate of nanoTiO₂ are studied. It is shown that the loading rate of nanoTiO₂ increases with decreased deionized water and increased nanoTiO₂ impregnation solution concentration; the loading rate of nanoTiO₂ initially increases and then decreases with increased alcohol content and dip-coating time, but the dip-coating time only has weak influence on the loading rate of nanoTiO₂. When the ratio of butyl titanate to alcohol is 1:9, the ratio of butyl titanate to water is 3:1, the dip-coating time is 20 min and the nanoTiO₂ impregnation solution concentration is 2 mg/ml, the loading rate of nanoTiO₂ reaches maximum, which is 33.64%.

Abstract: New degradable cushioning packaging materials based on bagasse pith, magnesium bisulfite spent liquor and reinforcing silica were prepared by press-molding process. The effects of precipitated silica loading and the specific surface area (S_BET) on the apparent density and the static compressive strength of cushioning packaging materials were investigated. Meanwhile, the microstructure and morphology of different types of silica fillers were analyzed by scanning electron microscopy(SEM). Static compressive strength of BPCPMs was improved significantly with the addition of 0.5%(w/w) silica. However, the compressive stress of BPCPMs increased at first and then decreased with increasing loading of silica. Increasing silica dosage increased cushion efficiency of BPCPMs at higher stress levels. The compressive stress increased with increasing S_BET value, and under high strain conditions, the increase scale in compressive stress also improved.

Abstract: A novel biodegradable and biocompatible composite of Poly (propylene carbonate) (PPC) and graphenes oxide (GO) was prepared by a solution blending method. The chemical structure, thermal properties and microscopic morphologies of the GO/PPC composites were characterized by Fourier transform infrared spectroscopy (FT-IR), thermo gravimetric analysis (TGA) and scanning electron microscopy (SEM). It was shown that the GO/PPC composites with 0.75 wt% GO performed a significant improvement on mechanical properties and thermal properties, as compared with the neat PPC. This composite could become a promising alternative to non-biodegradable for food packaging materials.

Abstract: In order to improve the adsorption performance of wooden activated carbon fibers (WACFs) and enlarge its application in food safety and fresh, the charcoal dust is used as pore-forming agent, and the absorption performance of WACFs for methylene blue (MB) by changing the liquid-solid rate, charcoal content, synthetics content and hydrochloric acid concentration is studied. The results show that: with the increase of liquid-solid ratio, the absorption capacity of WACFs for MB increases accordingly; with the increase of charcoal content and synthetics content, the absorption capacity both show the tendency of increasing first then reducing after accordingly, with the maximum absorption capacities of 534.61mg·g^-1 and 527.25mg·g^-1 respectively reached by 1% charcoal content and 4% synthetic content. When the hydrochloric acid concentration was below 15%, the absorption capacity increases linearly, while reduced when hydrochloric acid concentration was over 15%.

Abstract: The objectives of this study were to evaluate the antimicrobial efficacy of cinnamon essential oil (CEO) and rhubarb extract (REE) against 5 food-related microorganisms. The major active constituents of CEO were cinnamaldehyde (80.010%) and 2-methoxycinnamaldehyde (10.550%), and the major active constituents of REE were chrysophanic acid (54.950%) and physcion (13.270%). CEO and REE display strong inhibition against 5 strains. The checkerboard method was used to investigate the synergy antimicrobial potentiality of a combination of CEO and REE by analysis of the fractional inhibitory concentration index (FICI). The FICI was calculated and interpreted as synergy, addition, indifference, or antagonism. The combination showed additive efficacy against all tested microorganisms.

Abstract: Electrospinning is a technique that can be used to produce nanofibres from a polymeric solution or melt under the influence of a high electrostatic field [. In this paper, we used Acetone/N, N-Dimethyl acetamide (DMAc) and Acetic acid as the solvent, to explore the influencing factors of using electrospinning to prepare the nanofiber of cellulose acetate, and studied on how solvent, voltage and viscosity impact on the morphology and diameter of nanofiber. The results of the study show that: Acetone/DMAc as solvent, when the solvent ratio is 3:1, the spinning of the concentration is 4%～6%, the viscosity is 7.1～8.3 Poise, the voltage is 15kV, and deposition distance is 12cm, we could obtain the gelatin nanofibers with the diameter of 200-300 nanometer prepared by electrospinning. This study provided the theoretical basis for cellulose acetate prepared by electrospinning in antimicrobial food packaging materials development.

Abstract: The modified atmosphere packaging (MAP) and antibacterial film of low density polyethylene (LDPE) were made in the presence of nanoZnO or nanosilver materials. The effect of different content and different kind of nanometal materials on the tensile strength, oxygen permeability rate and the antibacterial properties of LDPE fresh-keeping film were studied, especially the effect of fresh-keeping properties on small tomatoes picked.

Abstract: In this paper, modified atmosphere packaging (MAP) film of fruit and vegetable was prepared through extrusion blow molding process.The LDPE was used as matrix resin and medical stone powder as the main filler. Stearic acid was added into film as a kind of surfactant. Effect of particle size, stearic acid proportion,filler amount and stretch pocessing on properties of MAP film was studied through measuring its oxygen and water vapor permeability,tensile strength as well as elongation ratio.Experimental investigation indicated that for preparing MAP film with high permeability, the controlled conditions such as 325 mesh medical stone powder, additive amount of 20 phr with stretch processing, stearic acid proportion of 2/10 were required.

Abstract: Chitosan-PE bi-layer films exhibit antimicrobial activity but poor antioxidant activity. Oregano essential oil (100μL/100mL) was incorporated into chitosan solution to improve films antioxidant and antimicrobial behaviors. The present work investigated the scavenging of O₂·, ·OH, DPPH radical and reducing power of film, antimicrobial activity was also evaluated. The results showed that the scavenging effect of film solution on O₂·, ·OH, and DPPH was 80.87%, 85.56%, and 87.24%, respectively. Reducing power of film increased with the improvement of oregano essential oil. The antibacterial activity against E. Coli and B. Subtilis increased from 80.77% to 96.15% and from 93.02% to 98.10%, respectively. The preservation experiments showed that chitosan-PE film incorporated with oregano essential oil could extend the shelf life of pork to 810 days at 4°C.