Advanced Materials Research Vols. 554-556

Abstract: A method for extraction of degradable polyethylene (PE) residues in soil was reported in this paper. PE powder (Mw=5000) which was taken as simulated PE residues were evenly mixed with different types of soils. The soil and PE powder mixtures were dissolved in HF:HCl acid mixture (5:2 (v/v)) for 50min at room temperature, followed by sequential washed using water, ethanol, sodium hydroxide and tetrahydrofuran at 45oC. The extraction procedure gave an average recovery rate of 82%. The results show that the soil type had no significant effect on PE recovery rate. The FT-IR spectra and the high temperature gel permeation chromatography (HT-GPC) illustrates that no significant changes in chemical structure and molecular weight and molecular weight distribution of PE after the extraction. The preliminary results obtained indicate that this method can be a new approach in studying the degradation of PE residues in soil.

Abstract: A random-arranged experimental design method was employed to optimize the technology of styrene/butylacrylate/acrylic acid (St/BA/AA) emulsion polymerization with high solid content. The random-designed experimental results were analyzed with regression analysis by using statistical analysis system (SAS), and the optimal regression equations between the principal factors and the emulsion properties were in turn established. It is shown that the viscosity of emulsions is greatly affected by the following factors: solid content, the interaction between the emulsifier content and solid content, the interaction between the initiator concentration and reaction temperature, the interaction between functional monomer and reaction temperature.

Abstract: Polyurethane-modified epoxy monoacrylates (PMEMA) containing two different UV- curable groups (double bond and epoxy groups) were synthesized. The changes of NCO groups during the synthesis process of PMEMA were measured by chemical titration method, and its Fourier Transform Infrared (FTIR) spectra were investigated. The results indicated that polyurethane chain segments can be grafted onto the epoxy monacrylates (EMA) by the reaction of NCO and OH groups. The FTIR of PMEMA showed that it contains both double bond of acrylic ester (UV radical curable) and epoxy groups (UV cationic curable).

Abstract: The kinetics of semibatch polymerization (i.e. slow monomer addition) with ABg monomer and Bf core was developed. The analytical expressions of molecular parameters, such as the molecular size distribution function, the average degree of polymerization and polydispersity index, were derived, which dependent on the structure of monomer and core molecule used. The molecular parameters are adjustable by selecting suitable core functionality (f), monomer functionality (g) and core/monomer ratio (α). Comparison with the batch (one-pot) polymerization indicates that the semibatch polymerization can extremely narrow the molecular weight distribution for the products made of AB_g monomer and Bf core.

Abstract: Removal of low concentration of phenol from aqueous solutions through the adsorption process by using crosslinked β-Cyclodextrin polymer (β-CD polymer) was investigated. The effects of contact time, sodium chloride content, contact temperature and initial concentration of phenol in the aqueous on adsorption capacity were evaluated through a series of batch experiments. The results show that β-CD polymer on the adsorption of phenol balanced after 6h. The adsorption process was apparently influenced by sodium chloride content, contact temperature and initial phenol concentration in aqueous solution. The adsorption behavior for phenol of β-CD polymer is fitted into the Freundlich isotherm.

Abstract: The modification methods of waste rubber powder(WRP) which contain mechanochemical, microwave, ultrasonic, devulcanization in supercritical material and microbial devulcanization method through cutting off three-dimensional network are described. More emphasis is put on devulcanization mechanism and the defects of each method as the devulcanization process is often accompanied with the main rubber chains degradation are also discussed. When modified WRP is added into rubber matrix, the mechanical properties of composite and compatibility between virgin rubber and WRP are improved. So the mode of core modification on WRP is built, through the broken three-dimensional network modification methods of WRP.

Abstract: Hyperbranched polyurethane (HPBU) was synthesized by the method of “arm first and core later”. The FT-IR and GPC were used to characterize the structure of HBPU. The results showed that the reaction happened as expected routine. Compared with common liner polyurethane, the Mn of HBPU increased 22% and Mw increased 37% at the same viscosity, which demonstrated that HBPU had advantage in low viscosity and easy flowing. The spectrum of X-ray shows the crystallinity of HBPU is higher than the PU, so the cell arranged of the HBPU is more regular.

Abstract: Polyurethane (PU), one of the six main categories of synthetic resins, has been used extensively in industry all over the world. Tung oil anhydride-ester polyol (TOAEP), prepared from the China special vegetable oil, Tung oil, was introduced into PU structure. The mechanical property, heat-resistance and morphological structure of the modified PU were studied. Experimental results showed that the hardness and tensile strength of the modified PU increases as the dose of TOAEP increasing while the elongation at break decreases, and the heat-resistance has been improved after modification. The modified PU’s hard segment phase is compatible with the soft segment phase.

Abstract: Polyether-polyester nonionic hydrophilic polyurethanes with amorphous soft segment phase are prepared from 4,4’- diphenylmethane diisocyanate (MDI), polybutylene adipate glycol 2000 (PBA2000) and polyethylene glycol 1000 (PEG1000) with 1,4-butanediol (BDO) as chain extender. Further more, the relationships between micro-phase structure and chemical structure of samples is investigated. The studies show that the chemical structure has remarkable effects on the micro-phase structure of hydrophilic polyurethane and micro-phase separation degree of the mixed soft domains.

Abstract: Superabsorbent polymers, which have been used for many applicaions, are an important class of polymers. Superabsorbent polymer based on organic montmorillonite (MMT) and xanthan gum(XG) were prepared by by free-radical graft polymerization of aceylic acid on XG in aqueous solution as a free radical initiator, and then organic montmorillonite (OMMT) was introduced as filler into superabsorbent. The effects of montmorillonite and xanthan on the swelling behaviour of the superabsorbent polymer had been studied in detail. Under the optimal synthesis condition, where the temperature was 65°C, the ratio between the AA monomers and XG was m (XG) : m(AA) = 4 : 1, the weight rate of the initiator and the cross-linker were 1.2% and 0.07%, and the neutralization degree of AA was 70%, the product attained the best water absorbency of 882 g/g in distilled water and 107 g/g in 0.9 wt.% NaCl solution.