Preparation of Modified PVA Copolymer by DAAM/ADH and Cross-Linking Mechanism for Paper

Herein, a novel modified polyvinyl alcohol(DA-IPVA) used as sizing agent was prepared by using diacetone acrylamide(DAAM) as graft monomer and N-(isobutoxymethyl)acrylamide(IBMA) as self-cross-linking monomer. The effect of the amount of DAAM on the properties of emulsion, film and sizing paper was discussed. The surface micro-structure of the sizing paper was characterized by SEM and AFM. The addition of DAAM/ADH and IBMA endowed DA-IPVA with cross-linked active group and increased cross-linking density and hydrophobicity after ADH was added into the emulsion and the cross-linking structure was formed. The enhancing mechanism of surface sizing agent for paper was revealed. The DA-IPVA can be cross-linked on the surface and inside of the paper to form a dense network structure, which improves the bonding force between the fibers. When the mole fraction of DAAM of the cross-linking monomer is 8%, the surface sizing performance of the paper is obviously improved compared with the base paper. The dry and wet strength is increased by 266.5% and 334.3% respectively, and the folding resistance is increased 2946.67%. This study can have a profound impact on the development of the technology of cross-linking surface sizing agent for paper.

Design of Sodium Alginate/Gelatin-Based Emulsion Film Fused with Polylactide Microparticles Charged with Plant Extract

This study aimed at designing emulsion films based on sodium alginate, gelatin, and glycerol, and their modification by the addition of lipids (cottonseed oil and beeswax). Film composition with the most promising properties was further modified by the incorporation of polylactide (PLA) microparticles with Calendula officinalis flower extract. PLA microspheres were obtained by the emulsion/solvent evaporation method. The size distribution of oily particles in emulsions was investigated. Mechanical properties, moisture content, UV-Vis spectra, and the color of films were analyzed, while biophysical skin parameters were assessed after their application to the skin. Moreover, the contact angles were measured, and the surface free energy of polymeric films was determined. An investigation of the amount of Calendula officinalis flower extract which can be incorporated into PLA microparticles was performed. The modification of the composition of films significantly influenced their physicochemical properties. The selected active ingredient in the form of plant extract was successfully incorporated into polymeric microparticles that were further added into the developed emulsion film. The condition of the skin after the application of obtained emulsion films improved. The prepared materials, especially containing microparticles with plant extract, can be considered for designing new cosmetic forms, such as cosmetic masks, as well as new topical formulations for pharmaceutical delivery.

Proton Radiography by Multiple Coulomb Scattering with Nuclear Emulsion Detectors

The possibility of performing proton radiography by using the proton angular spread due to Coulomb multiple scattering was investigated, for the first time, with an emulsion film detector. Two different phantoms were irradiated with the therapeutic proton beam at the Paul Scherrer Institut (PSI) in Villigen, Switzerland. The first one is a simple polymethylmethacrylate (PMMA) block having two different thicknesses (4 cm and 3 cm), and the second one is a PMMA cube with five aluminum rods embedded along a diagonal. Only one emulsion film was needed to perform the radiography, an important issue as the analysis of this kind of detector is time-consuming. Furthermore, the method showed an enhanced contrast when high atomic-number materials are traversed. This gives an advantage, when compared to proton range radiography.

Hydrophobicity of Polyacrylate Emulsion Film Enhanced by Introduction of Nano-SiO2 and Fluorine

This study proposes to utilize modified Nano-SiO2/fluorinated polyacrylate emulsion that was synthesized with a semi-continuous starved seed emulsion polymerization to improve the hydrophobicity, thermal stability, and UV-Vis absorption of polyacrylate emulsion film. To verify the proposed method, a series inspection had been conducted to investigate the features of the emulsion film. The morphological analysis indicated that Nano-SiO2 was surrounded by a silane molecule after modification, which can efficiently prevent silica nanoparticles from aggregating. Fourier transform infrared spectra confirmed that modified SiO2 and dodecafluoroheptyl methacrylate (DFMA) were successfully introduced to the copolymer latex. The particle size of latex increased with the introduction of modified Nano-SiO2 and DFMA. UV-Vis absorption spectra revealed that modified silicon nanoparticles can improve the ultraviolet shielding effect obviously. X-ray photoelectron spectroscopy illustrated that the film–air interface was richer in fluorine than film section and the glass side. The contact angle of modified Nano-SiO2/fluorinated polyacrylate emulsion containing 3 wt % DFMA was 112°, slightly lower than double that of polyacrylate emulsion, indicating composite emulsion films possess better hydrophobicity. These results suggest that introducing modified Nano-SiO2 and fluorine into polyacrylate emulsion can significantly enhance the thermal stability of emulsion films.

Chitosan Modified Corn Starch and Its Application as a Glass Fibre Sizing Agent

Chitosan-modified corn starch was prepared and then applied as a glass fiber sizing agent. The effect of the chitosan on starch-based emulsion, film and sized glass fiber was studied. When 5 % of the chitosan was added, the overall performance of the modified film-forming agent was optimal. The viscosity, surface tension and zeta potential of the sizing agent were 44.99 mPa·s, 51.29 mN·m[sup]-1[/sup] and 4.5 mV, respectively. The modified sizing agent could easily spread over the surface of glass fibre, and conglutinated to the glass surface firmly. The tensile strength and stiffness of modified-starch glass fiber reached 0.43 N·tex[sup]-1[/sup] and 4.96 cm. Glass fiber with good overall performance was obtained.