Studies on the Uptake of Rare Earth Elements on Polyacrylamidoxime Resins from Natural Concentrate Leachate Solutions

Synthesis of poly(acrylamidoxime) resin from polyacrylonitrile performed with different crosslinking ratios 2, 5, and 10 wt% of divinylbenzene as crosslinking agent, using methylbenzoate and dioctylphthalate as pore producing solvent, the reaction mixture occurred under nitrogen. Studies carried out on diluted solution from rare earth elements (REEs) concentrate contains impurities as Cu²⁺, Ni²⁺, Zn²⁺, Fe³⁺, Al³⁺, Si⁴⁺, Th⁴⁺, U⁶⁺, Ca²⁺, and K⁺. Changing some parameters as pH of the solution, time of feeding and type of acid as HCl, HNO₃, H₂SO₄. The adsorption efficiency of resin is in the order pH 6 > pH 5 > pH 4 > pH 2 with excluding pH 6 due to the precipitation of some of REEs with the impurities and complete precipitation of Dy ion during pH adjustment, the adsorption in HNO₃ > HCl > H₂SO₄ media.     

Synthesis and thermal properties of a new styryl-functionalized pentafulvene glassy carbon precursor

The first preparation of a styryl-functionalized aryl pentafulvene 4 was carried out. In the crystal structure of 4, the packing of fulvene molecules results in the shortest intermolecular contacts between aligned vinyl groups. Thermal reactivity studies of 4 (DSC and TGA, under N₂) revealed a small difference between the melting point (120 °C) and the T_onset for cross-linking (125 °C), and provided strong evidence for the production of a network material (net4) due to reactivity of the attached styryl group. Pyrolysis of net4 under N₂ gave a glassy carbon product in low yield as revealed by powder X-ray and TGA analyses (carbon yield (TGA) of 38% (900 °C)).     

Allyl phthalazinone synthesis,polymerization and polymer properties

A phthalazinone monomer with an allyl group, i.e. 4-（3-allyl-4-hydroxyphenyl）phthalazin-1（2H）-one, was synthesized and then copolymerized with 4-（4-hydroxylphenyl）（2H）-phthalazin-1-one and 2,6- diflurobenzonitrile by means of aromatic nucleophilic polycondensation to provide a series of crosslinkable poly（aryl ether nitrile）s. The virgin copolymers exhibited good solubility in polar organic solvents with relative high molecular weights （Mw： 45,130-58,403, inherent viscosities： 0.58-0.75 dL/ g）. After cross-linking, the thermal stability and solvent resistance of the polymer increased.     

交联壳聚糖缩水杨醛螯合树脂的制备及性能研究

以壳聚糖缩水杨醛产品为原料,环氧氯丙烷为交联剂,加入相转移催化剂,合成交联壳聚糖缩水杨醛螯合树脂的新工艺。考察了各种因素驿交联反应的影响及树脂的吸附性能。结果表明,该树脂具有对Ｃｕ（ＩＩ）吸附容量高,吸附选择性系数ＫＣｕ（Ⅱ）／Ｆｃ（Ⅲ）＝１３．５５,经简单再生后重复使用次数多的特点。     

Crosslinking network structure governing particle shape and size distribution by one-step emulsion polymerization in the presence of particle coagulation

In this study, sub-200?nm, crosslinked latex particles with a narrow particle size distribution were prepared by one-step emulsion polymerization in the presence of particle coagulation. The relationship between the particle shape and particle coagulation was investigated by varying the time of crosslinking network structure formation and particle coagulation. Particles with irregular shapes such as doublet, triplet, and ellipsoid were obtained using divinylbenzene (DVB) and ethylene glycol dimethacrylate (EGDMA) as the crosslinking agents, because the crosslinking network structure of particles was formed before the particle coagulation. In contrast, latex particles with a uniform spherical shape were also prepared using triallyl isocyanurate (TAIC) or dihydrodicyclopentadienyl acrylate (DCPA) as the crosslinking agents by delaying the time of crosslinking network structure formation. Alternatively, uniform spherical latex particles were prepared by bringing forward the particle coagulation time using cationic initiator, 2, 2′-azobis (2-methylpropionamidine) dihydrochloride (AAPH). This study presents a new idea that would further broaden the application of particle coagulation in emulsion polymerization.     

Polymer networks by molecular dynamics simulation: Formation, thermal, structural and mechanical properties

A molecular dynamics simulation method is presented and used in the study of the formation of polymer networks. We study the formation of networks representing the methylene repeating units as united atoms. The network formation is accomplished by cross-linking polymer chains with dedicated functional end groups. The simulations reveal that during the cross-linking process, initially branched molecules are formed before the gel point; approaching the gel point, larger branched entities are formed through integration of smaller branched molecules, and at the gel point a network spanning the simulation box is obtained; beyond the gel point the network continues to grow through the addition of the remaining molecules of the sol phase onto the gel (the network); the final completion of the reaction occurs by intra-network connection of dangling ends onto unsaturated cross-linkers. The conformational properties of the strands in the undeformed network are found to be very similar with the conformational properties of the chains before cross-linking. The uniaxial deformation of the formed networks is investigated and the modulus determined from the stress-strain curves shows reciprocal scaling with the precursor chain length for networks formed from sufficiently large precursor chains (N ≥ 20).     

硬链段浓度对RIM交联聚氨酯结构和性能的影响

用l-MDI/1,4-BDO/PPO-EO快反应体系,考察硬段浓度对聚氨酯结构与性能的影响。发现样品的交联度、模量和抗张强度随硬段浓度增加而提高,交联趋向均匀,断裂伸长率在浓度30％处出现最大值。ATR-FTIR和DSC分析表明,微相分离程度随硬段浓度增大而降低。     

Unique thermal behavior of acrylic PSAs bearing long alkyl side groups and crosslinked by aluminum chelate

An acrylic pressure-sensitive adhesive (PSA), bearing octadecyl acrylate, methyl acrylate and acrylic acid groups, and crosslinked by aluminum acetylacetonate (AlACA), displayed behavior unique among acrylic PSAs in that its adhesion, which decreases with an increase in temperature, began to increase again from around 150 °C. In order to understand this behavior, the structure and thermal properties of the PSA were investigated in detail, along with another PSA crosslinked by a covalent crosslinking agent (Az). From thermal mechanical analysis, the PSA with ionic crosslinks (AlACA) showed three softening points at 20, 60, and 160 °C. In comparison, the PSA covalently crosslinked by Az only exhibited two softening points (at 20 and 60 °C). The softening point at 160 °C is clearly related to ionic chelate crosslinking. DSC measurements indicated that the softening point at 20 °C resulted from melting of the ordered octadecyl group, and the softening point at 60 °C was due to an increase in the mobility of the main chain. The temperature dependence of viscoelastic measurements revealed that the viscosity of the PSA crosslinked by AlACA increased at around 160 °C. From these results, we considered that the distinctive adhesion of the PSA crosslinked by AlACA could be due to ligand exchange at the aluminum crosslinking points, which are chelated by carboxy groups built in the main chain.     

Radiation effects on dihydroxypropyl-chitosan

Dihydroxypropyl-chitosan (DHP-chitosan), a derivative of chitosan used in practical applications, is hardly soluble in water because of the strong intermolecular hydrogen bonding. In order to improve its even more advanced practical applications, some further modifications of the polymer using electron beam radiation technique were carried out. In the current work, diluted lactic acid was used to improve the solubility of DHP-chitosan as a subversive of hydrogen bonding. The effects of electron beam radiation on the DHP-chitosan in solid state and solution state were investigated. It was found that solid state and low concentrated solution state result in degradation and high concentrated solution state is favorable for crosslinking. And a simple, effective strategy to achieve a novel DHP-chitosan hydrogel without any crosslinking agents was developed in a high concentrated polymer solution system under irradiation.