Advanced Materials Research Vol. 380

Abstract: Poly(L-lactic acid ) (PLLA) /oganic montmorillonite (OMMT) composites were prepared by means of melt-mixing using a twin-screw extruder. The mechanical properties and melt flow rate of the composites were investigated, and their crystallization structure and thermal properties were characterized by X-Ray Diffraction (XRD), Differential Scanning Calorimeter (DSC), and thermogravimetric analysis (TG). It was shown that the tensile strength, elongation at break and bending strength of the PLLA/OMMT composites firstly increased and then reduced along with the increase of the content of OMMT. The melt flow rate of the composites was obviously improved and the crystallinity was increased. OMMT played a heterogeneous nucleation role in the composites, while it had little impact on thermal stability of the composites.

Abstract: The influence of temperature on oxygen and water vapour permeation in cast soy protein isolate (SPI) films was investigated at the range of 10–40° C at 50% relative humidity. At tested temperatures, the SPI films exhibited transmission rate values of 22.48–150.90 g m⁻²day⁻¹ and 5.67–67.48 cm³ m⁻²day⁻¹ for water vapour and O₂, respectively. The results indicated that the relationship between temperature and the oxygen/water vapour transmission rate of the SPI films followed an exponential grow curve [y=A*exp(x/B) + C]. Furthermore, the activation energy (E_a) value of the O₂ permeation process was calculated by fitting the Arrhenius model to the experimental data.

Abstract: Based on a single-factor experiment method, the changes of water content, fatty acid content, reducing sugar content and viscosity value of rice during storage are analyzed under different mixed fresh atmosphere CO₂ and N₂ treatment with PA/PE composite membrane. The result indicates the best ratio of mixed gas treatment is 60% CO₂ and 40% N₂.

Abstract: Gas permselectivity film is an emerging material which enables it with gas selective permeability functions so as to keep the preservation atmosphere including water vapor, oxygen and other gas concentration of inner packages and thus extends the preservation period of fresh fruits. In this work, the monomer Hexamethyldisilazane (HMDS) and oxygen gas were applied as the precursor and reaction gas, the gas permselective material were deposited on PET and Chitosan substrate by plasma enhanced chemical vapor deposition (PECVD) method, respectively. Different reaction parameters such as monomer proportions, plasma input powers and deposition time were investigated respectively. The film properties were analyzed by Surface Profiler thickness test, Fourier Transform Infrared Spectroscopy (FTIR), water vapor transmission rate test (WVTR) and oxygen transmission rate test (OTR). The experimental results showed that plasma input power and monomer ratio influence the gas selective permeation (OTR/WVTR ratio) greatly. And also, the mechanism of gas selective permeation of the film was preliminary discussed.

Abstract: The residual contaminants in paper-plastic food packaging materials can migrate into both surface and inside of food, and consequently harm consumer’s health. Due to this fact, the safety of food packaging materials has attracted concerns from all over world. In this study, the residual contaminants were extracted by ethanol from paper-plastic food packaging materials under ultrasonic condition and different temperatures firstly, then the extractives were concentrated by rotary evaporator, and finally the concentrated contaminants were characterized by means of Gas Chromatography-Mass Spectrometry (GC-MS) detection. The results showed that the following contaminants are detected in the paper-plastic food packaging materials: plasticizer including dibutyl phthalate (DBP) and di-2-ethylhexyl phthalate (DEHP); antioxidants including 2,6-Di-tert-butyl-p-benzoquinone and 2,6-Di-tert-butyl-4-methylphenol (BHT), and solvents in printing ink production including n-Hexadecane and n-Heptadecane. Upon the test results, the conclusion is that more residual contaminants can be detected under high temperatures. This study is helpful for quality control of paper-plastic food packaging materials and has built basic foundation for future migration research.

Abstract: Nano-TiO₂ was modified with amino propyl triethoxy silane (KH550). The PVA/nano-TiO₂ composite film was formed through a solution casting method. Nano-TiO₂ and the composite film were characterized and the results show that the PVA/nano-TiO₂ composite prepared by direct-blending method has better dispersibility and lower weightlessness than the unmodified PVA/nano-TiO₂. The tensile strength of the PVA/nano-TiO₂ composite was increased by 66.35%. The coefficient of the moisture permeability and permeability coefficient of the PVA/ nano-TiO₂ composite were decreased by 29.94% and 56.67%, respectively.

Abstract: In situ melt copolycondensation was proposed to prepare biodegradable copolyester nanocomposites based on degradable components poly(L-lactic acid) (PLA), rigid segments poly(butylene terephthalate) (PBT), and nanoparticles polyhedral oligomeric silsesquioxanes (POSS). The morphologies and dispersions of two POSS nanoparticles (POSS-NH₂ and POSS-PEG) in the copolyester PLABT matrix and their effects on the mechanical properties were investigated. The results demonstrated that the morphologies and dispersions of POSS-NH₂ and POSS-PEG showed quite different characteristics. POSS-PEG took better dispersion in the PLABT, while POSS-NH₂ had poor dispersions and formed crystalline microaggregates. Due to the good dispersion and strong interfacial adhesion of POSS-PEG with the matrix, the tensile strength and Young’s modulus were greatly improved from 6.4 and 9.6 MPa for neat PLABT up to 11.2 and 70.7 MPa for PLABT/POSS-PEG nanocomposite. Moreover, the incorporation of POSS-PEG could impart macromolecular chains good flexibility and improve the mobility of the chains, so the the elongation at break of PLABT/POSS-PEG nanocomposite dramatically increased from 190 to 350 % compared with neat PLABT.

Abstract: In this paper, the polyurethane prepolymer (Component A) was synthesized with PBA, Castor oil, and IPDI as raw material. The structure and viscosity of PU prepolymer was characterized by IR spectra and rotary rheometer. The thermal performance, adhesion properties and water resistance of cured adhesive films were respectively determined by Thermogravimetric analysis (TG), T-style peel strength test, and water absorption test. The results showed that the addition of castor oil reduced the viscosity of prepolymer and greatly improved the water resistance of cured adhesive, but never affected the thermal performance of adhesive. Besides, castor oil was cheaper, easily obtained and more natural than other polyols. However, castor oil slightly decreased the adhesion strength of adhesive. So the amount of castor oil should be considered.

Abstract: Two kinds of photo-crosslinkable polymers with a coumarin-containing and cinnamate-containing side group were synthesized in this paper. The structure of the intermediates, monomers and polymers were characterized with FTIR and 1HNMR measurement. Differential scanning calorimetry (DSC), hot stage polarized optical microscopy (POM) were employed to study the phase-transition temperature, mesophase texture. UV-VIS spectrophotometer was used to survey the ultraviolet absorption performance of the polymers. The results showed that the monomer with cinnamate group showed nematic phase and smectic phase over a wide temperature range. What’s more, the ultraviolet absorption peak of the polymer with cinnamate group was at about 285 nm, and the ultraviolet absorption peak of the polymer with coumarin group was around 311.00 nm.

Abstract: Lithographic printing press must maintain a stable standard printing environment; we need to maintain the ink-water balance for achieve stability print quality. Not only stable for ink supply, but also stable supply of dampening solution from dampening circulation system. The study tries to conduct less proportion of alcohol to reduce emissions of volatile IPA, using green printing technology in the standard production. This study analyzed a variety of automatic sheet-fed offset press dampening system to study how to control the tank fluid additives, and reduce alcohol consumption. Design standard operation of "automatic green formula system“, the system should contain four main functions: purity water systems, precise formulation systems, circulated filtration system and computer numerical control system. Its purpose: to make the operation under the automated water quality standards, make stable print quality and increase printing capacity, increase product yield, reduce pollution. The water dampening system makes the quality and stability while reducing pollution emissions.