Jiugao Yu

Fabrication and Characterization of Citric Acid-Modified Starch Nanoparticles/Plasticized-Starch Composites

Starch nanoparticles (SN) were prepared by delivering ethanol as the precipitant into starch-paste solution dropwise. Citric acid (CA) modified SN (CASN) were fabricated with the dry preparation technique. According to the characterization of CASN with Fourier transform infrared, X-ray diffraction, rapid visco analyzer, and scanning electron microscopy (SEM), amorphous CASN could not be gelatinized in hot water because of the cross-linking, and most of CASN ranged in size from about 50 to 100 nm. The nanocomposites were also prepared using CASN as the filler in glycerol plasticized-pea starch (GPS) matrix by the casting process. SEM revealed that CASN was dispersed evenly in the GPS matrix. As shown in dynamic mechanical thermal analysis, the introduction of CASN could improve the storage modulus and the glass transition temperature of CASN/GPS composites. The tensile yield strength and Youngs modulus increased from 3.94 to 8.12 MPa and from 49.8 to 125.1 MPa, respectively, when the CASN contents varied from 0 to 4 wt %. Moreover, the values of water vapor permeability decreased from 4.76 x 10(-10) to 2.72 x 10(-10) g m(-1) s(-1) Pa(-1). The improvement of these properties could be attributed to the good interaction between CASN filler and GPS matrix. The comprehensive application of green chemistry principles were demonstrated in the preparation of CASN and CASN/GPS composites.

Preparation and characterization of glycerol plasticized-pea starch/ZnO-carboxymethylcellulose sodium nanocomposites.

Among natural polymers, starch is one of the most promising biodegradable materials because it is a renewable bioresource that is universally available and of low cost. However, the properties of starch-based materials are not satisfactory. One approach is the use of nano-filler as reinforcement for starch-based materials. In this paper, a nanocomposite is prepared using ZnO nanoparticles stabilized by carboxymethylcellulose sodium (CMC) as the filler in glycerol plasticized-pea starch (GPS) matrix by the casting process. According to the characterization of ZnO-CMC particles with Fourier transform infrared (FTIR), Ultraviolet-visible (UV-vis), X-ray diffraction (XRD), transmission electron microscope (TEM) and thermogravimetric analysis (TG), ZnO (about 60 wt%) is encapsulated with CMC (about 40 wt%) in ZnO-CMC particles with the size of about 30-40 nm. A low loading of ZnO-CMC particles can obviously improve the pasting viscosity, storage modulus, the glass transition temperature and UV absorbance of GPS/ZnO-CMC nanocomposites. When the ZnO-CMC contents vary from 0 to 5 wt%, the tensile yield strength increase from 3.94 MPa to 9.81 MPa, while the elongation at break reduce from 42.2% to 25.8%. The water vapor permeability decrease from 4.76 x 10(-10) to 1.65 x 10(-10) g m(-1) s(-1) Pa(-1).

Characterization of magnetic soluble starch-functionalized carbon nanotubes and its application for the adsorption of the dyes

Soluble starch-functionalized multiwall carbon nanotube composites (MWCNT-starch) were prepared to improve the hydrophilicity and biocompatibility of MWCNTs. Characterization of the MWCNT-starch by Fourier transform infrared (FTIR) spectroscopy, ultraviolet-visible (UV-vis) spectroscopy, X-ray diffraction (XRD), transmission electron microscope (TEM) and thermogravimetric analysis (TG), showed that the starch component (about 14.3 wt%) was covalently grafted onto the surface of MWCNT. MWCNT-starch-iron oxide composites, intended for use as adsorbents for the removal of dyes from aqueous solutions, were prepared by synthesizing iron oxide nanoparticles at the surface of MWCNT-starch. Starch acts as a template for growth of iron oxide nanoparticles which are uniformly dispersed on the surface of the MWCNT-starch. MWCNT-starch-iron oxide exhibits superparamagnetic properties with a saturation magnetization (23.15 emu/g) and better adsorption for anionic methyl orange (MO) and cationic methylene blue (MB) dyes than MWCNT-iron oxide.

Graft copolymerization of starch–AN initiated by potassium permanganate

The initiating ability of the potassium permanganate in the graft copolymerization of acrylonitrile onto starch was studied. The results indicate that the grafting parameters, such as concentrations of potassium permanganate, acrylonitrile, starch, and catalyst acids, all have significant effects on the graft copolymerization and the components of the graft copolymers, and this offers methods to adjust the properties of the graft copolymers. The sources of starch and corn starch derivatives both affected the components of the graft copolymers, which showed the influence of functional group on the grafting ability of starch. The preheat treatment and preoxidation of starch, as well as the adding sequence of the reactants all influenced the graft copolymerization, from which some suggestions about the grafting procession could be obtained.

A Study on the Properties of Starch/Glycerine Blend

In this paper, the mechanical and rheological properties. and the microstructure of the starch-glycerine blend prepared by a single-screw-extruder have been studied. Considering the rheology of the blend under different temperatures, we calculated the activation energy of the fluid of the blend to be 122.5 KJ/mol. Through DSC analysis, the equation describing the relation between the percentage of glycerine (B) and the glass transition temperature T g of the blend was established: T g = 105.18-96.06.B.

Conformation and location of amorphous and semi-crystalline regions in C-type starch granules revealed by SEM, NMR and XRD

The conformations and locations of amorphous and semi-crystalline regions in C-type starch granules from Chinese yam were evaluated by a combination of morphology and spectroscopy studies during acid hydrolysis. Scanning electron micrographs showed that amorphous or less crystalline areas were essentially located in the centre part of C-type starch granules, whereas the semi-crystalline and amorphous growth rings were found mainly in the outer part of the granules. (13)C cross-polarization magic angle spinning NMR ((13)C CP/MAS NMR) showed that amorphous regions were hydrolyzed faster than the crystalline ones. In addition, B-type polymorphs were shown to be hydrolyzed more rapidly than A-types. Powder X-ray diffraction (XRD) also revealed that the B-polymorph was hydrolyzed more rapidly than the A-type. XRD showed that the amorphous or less crystalline areas were mainly located in the core of starch granules, while the amorphous growth rings are distributed toward the outside of the granules and alternatively arranged with semi-crystalline growth rings. The amorphous or less crystalline areas predominantly consisted of the B-polymorph whereas the outer semi-crystalline and amorphous growth rings were mostly composed of the A-polymorph.

Comparison of Transition Metals in the Graft Copolymerization of Vinyl Monomers onto Starch

The ability to graft acrylonitrile (AN) onto starch initiated by various transition metals such as Mn(VII), Cr(VI), V(V) and Fe(III) were compared in the existence of sulfuric acid in different concentrations. The results showed that the grafting potential of Fe(III) is the lowest, while Mn(VII) is the highest of these transition metals discussed. The catalyzing ability of varieties of acids, including perchloric acid, sulfuric acid, nitric acid and hydrochloric acid, in the graft copolymerization of acrylonitrile onto starch was studied; and the graft ability of monomers such as acrylaniide (AM), acrylic acid (AA) and methyl methacrylate (MMA), was compared. The experimental data indicates that the catalytic abilities of acids are related to their capability of providing protons. The granuluar structure of starch and its graft copolymer were investigated with scanning electron microscopy, infrared spectroscopy, and thermogravietry.

The accelerated degradation of aqueous polyacrylamide at low temperature

The accelerated degradation of aqueous polyacrylamide at low temperature was studied. The selected degradation agents included several peroxides, such as potassium persulfate (K2S2O8), ammonium persulfate ((NH4)2S2O8), hydrogen peroxide (H2O2), and the potassium persulfate–sodium thiosulfate (K2S2O8–Na2S2O3) redox system. The redox system showed the highest degradation rate at the first 2 hours, but its final degradation level was lower than that of potassium persulfate. The degradation temperature, concentration of potassium persulfate and polyacrylamide, and original molecular weight of polyacrylamide all affected the degradation rate and final degradation level.

Preparation and Properties of Starch-Based Film Using N-(2-hydroxyethyl)formamide as a New Plasticizer

N-(2-hydroxyethyl)formamide (HF) was synthesized efficiently and used as a new plasticizer for corn starch to prepare flexible starch film. The hydrogen bond interaction between HF and starch was proved by Fourier-Transform Infrared (FT-IR). By scanning electron microscope (SEM), starch granules were completely disrupted, and the homogeneous materials were obtained. The crystallinity of corn starch and HF-plasticized starch film (HSF) was characterized by X-ray diffraction (XRD). Water vapor permeability of HSF was higher than that of glycerol-plasticized starch film (GSF). The elongations at break of HSF were higher than those of GSF at relative humidity 33%.

Study on degradation mechanism of polyethylene films containing additives with metal ions at a simulated composting temperature

In this article, the degradation mechanism of PE films containing additives with metal ions at a simulated composting temperature has been studied. The hydroperoxide concentration [POOH] in the films was traced quantitatively by using the iodometric potentiometric titration, compared with Fourier transform infrared spectrometry (FTIR). The results show that [POOH] increases during the early stage of degradation, followed by a more or less flat maximum before it starts to decrease. At the same time, similar results are obtained by the FTIR analysis. Besides, it is found that the rate laws for the carbonyl index and [POOH] increases seem more complicated, instead of an exponential-type increase in the early stage of the oxidation. When they are fitted by polynomial equations, the greater the rate of degradation, the more the number and content of the high-power members in the polynomial.