A graft copolymer of oleic acid (OA) onto low-density polyethylene (LDPE) was prepared using dicumyl peroxide (DCP) as an initiator in the molten state. The grafting was carried out in a Haake rheometer. The effects of the reaction time and the amount of DCP and the monomer on the percentage of grafting were studied. The rheological behavior and the melt-flow rate of the graft copolymer (LDPE-g-OA) were also investigated. FTIR spectroscopy and a mass spectrum were used to characterize the structure of LDPE-g-OA. The experimental results showed that when the OA amount was 10 wt % and the DCP amount was 0.4 wt % based on the LDPE the percentage of grafting of LDPE-g-OA, prepared by maintaining the temperature at 170

Crosslinked sodium polyacrylate as a superabsorbent was prepared by inverse suspension polymerization with cyclohexane as the continuous phase and sorbite anhydride monostearic acid ester (span-80) as the dispersant. The crosslinking degree was regulated by NaOH. The distilled water absorbency (WA) of the polymer gel was about 700 times its own weight if the gel was allowed to swell at roomtemperature for 24 h. WA under various conditions, such as varying pH, temperature, reaction time, neutralization, and cyclohexane concentration, was investigated and optimized. Our results revealed that the optimal reaction conditions were 55

The intrachain and interchain hydrogen bonding of poly (N-isopropylacrylamide) (PNIPA) and intermolecular hydrogen bonding between PNIPA chains and the solvent molecules in the mixed solvent of methanol and water have been quantitatively investigated by using Fourier transform infrared (FTIR) spectroscopy at 25℃ In this spectroscopic system with curve fitting program, we found that in the C-H stretching region, both the N-isopropyl group and the backbone underwent conformational change upon the solvent composition. An analysis of the amide I band suggested that the amide groups of PNIPA were mainly involved in intermolecular hydrogen bonding with water molecules, and the polymer chains were flexible and disordered in the mixed solvent when the methanol volume fraction (Xv) was lower than 15%. While vv was in the range of 15-65%, about 30% of these intermolecular hydrogen bonding between the polymer and water were replaced by intrachain and interchain hydrogen bonding, consequently, PNIPA shrinked as aggregates. If Xv was above 65%, the interchain hydrogen bonding became predominant due to the solubility characteristics of amphiphilic methanol, and the PNIPA system was homogeneous solution again. We believe that the reentrant transition is related to the weaker interaction between PNIPA molecules and methanol–water complexes, (H2O)m(CH3OH)n (m/n=5/1, 5/2, 5/3, 5/4, 5/5) as compared to that between PNIPA and free water or free methanol.

Laser light scattering (LLS) was used to investigate the concentration dependence of intrachain and interchain associations of poly(vinyl alcohol) (PVA) in aqueous solution after different freezing-and-thawing cycles. Our results showed that if the PVA concentration (C) was much lower than its gelation concentration (Cgel), the average hydrodynamic size of the PVA chains became smaller after a cryogenic treatment, which was attributed to the change of the chain conformation from an extended coil to a compact globule because the static LLS results indicated that there was no change in the weight average molecular weight (Mw). This rules out a previously speculated degradation or scission of the PVA chains. When C was higher than Cgel, the apparent hydrodynamic size of the PVA chains was much larger and the scattering intensity became much stronger after the same cryogenic treatment, indicating the interchain association.

A hydrogel, with water content more than 97.0 wt%, was prepared through crosslinking sodium carboxymethylcellulose (Na-CMC) with AlCl3, The effects of amount of crosslinker, water, Na-CMC and the reaction temperature on modulus and biodegradation of the hydrogel were investigated and optimized. At the same time, the factors of amount of antiseptic, nutriments and different soils on the biodegradation of the hydrogel were also discussed in detail. The results showed that the hydrogel had better biodegradation and strength when the mass ratio of crosslinker to Na-CMC was 0.13 at room temperature. The degradation rate of the hydrogel was enhanced by addition of nutrient element especially by addition of urea. The results of biodegradation in different soils showed sand soil is favorable to degradation of the hydrogel.