The synergetic influence of silane-grafting and polar additives (EVA) on the water tree resistance of the low density polyethylene has been investigated. A series of samples obtained before and after hydration have been characterized by measuring gel content, infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and dielectric measurements. The results obtained clearly show that the silane condensation occurred and that the silane-grafting and polar additives have synergetic effects on the water tree resistance of LDPE with little influence on its dielectric properties, e.g. the dielectric breakdown strength, dielectric permittivity and loss tangent.

Transparent ZrO2-polyurethane nanocomposites with high refractive index were prepared by dispersing ZrO2 nanoparticles in a polyurethane matrix via ligand molecule engineering. TEM showed that the inorganic particles were well dispersed within the polymeric network with no significant macroscopic agglomeration. By controlling the phase separation it was possible to obtain transparent zirconia nanostructured coatings, characterized by improved mechanical and thermal properties. UV-Vis spectra indicated that the coatings still maintained transparency in the visible light. The refractive index of the UV-cured films depends linearly on the ZrO2 content and varies from 1.475 to 1.625 (20 wt%) at 633 nm. These coatings could find advanced applications in coatings of optical and electronic devices.

In the present work, new thermally stable polymers containing 1,3,4-oxadiazole units have been synthesized through Huisgen reaction of the aromatic bis-tetrazole compounds with the aromatic/aliphatic bis-acid chlorides in pyridine as solvent. The obtained polymers are insoluble or slightly soluble in polar aprotic solvents such as DMSO and DMF. Thermal analyses of the polymers using DSC and TGA techniques showed that the polymers had improved thermal stabilities. The model reaction was also investigated and the resulting bis-1,3,4-oxadiazole compounds were characterized by conventional spectroscopic methods.

A diamine containing ether and ester units, as basic monomer for the preparation of polyamides, was prepared via three consecutive reactions. Nucleophilic substitution reaction of 1,4-dihydroxy benzene with 4-nitrobenzoyl chloride produced 4-hydroxyphenyl 4-nitrobenzoate (HPNB). Reduction of nitro groups to amino groups using Fe and HCl resulted in preparation of 4-hydroxyphenyl 4-aminobenzoate (HPAB). The diamine was synthesized through nucleophilic substitution reaction of HPAB with 2,6-dichloropyridine. The precursors and diamine were fully characterized by common methods, and the diamine was polycondensed with different diacid chlorides in the presence of an acid scavenger to prepare new polyamides. The polyamides were characterized, and their physical properties including thermal stability and behavior, inherent viscosity and solubility were studied.

The cationic ring-opening polymerization of 1-azabicyclo[4.2.0]octane, commonly called conidine (1) was studied with some chiral tricyclic amino acid esters (6a-6f) as acylation agents to obtain optically active biopolymers (8a-8f) of the different masses. The structures of the new compounds were confirmed by FT-IR, UV and NMR, and the distribution index of the molecular weights of the polymers was determined from SEC measurements.

The melt electrospinning of PMMA was investigated. The averaged fiber diameter thus obtained was reduced from 34.0μm to 19.7μm by adding di-(2-ethylhexyl)phthalate to reduce viscosity of the molten PMMA, and it further lowered down to 4.0 μm when a KCl/ice-water solution was used as collection media. A comparison study on the PMMA fibers made through melt electrospinning and done by solution electrospinning was made. It was found that solution electrospinning was capable of fabricating very thin fibers as small as to a nanometer size, but resulted in a much wider fiber diameter range than melt-electrospinning did. In general, within some extent an increase in applied voltage and amount of the additive or a decrease in collection distance can give rise to a decreased fiber diameter and improved mechanical performance for the PMMA fibers by melt electrospinning. It was also indicated that the mechanical properties of the PMMA fibers made through melt-electrospinning were superior to those by solution elctropspinning.

The cationic polymerizations of isobutylene (IB) coinitiated by AlCl3 were carried out in solvent mixture of n-hexane/methylene dichloride (n-hex/CH2Cl2) of 60/40 V/V in the presence of ethyl benzoate (EB) at various temperatures range from -80°C to -30°C. The effects of EB concentration ([EB]) and polymerization temperature on monomer conversion, weight-average molecular weight (Mw) and molecular weight distribution (MWD, Mw/Mn) of polyisobutylene (PIB) products were investigated. The rate of polymerization decreased while Mw of PIB products increased with increasing [EB]. The polymers with high molecular weight could be prepared in the presence of a suitable amount of EB. Significantly, the polymers with high Mw of 80.2×104 and 65.4 ×104 could be produced at -80°C and -70°C at [EB] = 0.24 ×10-3 mol/L respectively, which were much higher than that (Mw = 57.9 ×104) of PIB prepared at -100°C in the absence of EB. A simple but effective method for preparing the high molecular weight polyisobutylenes was developed in this work. It has been also found that the activation energy for propagation (Ep) depended on the polymerization temperature range in the presence of EB. An obvious inflection of the linear plots of lnXn versus 1/Tp occurred at the temperature range from -60°C to -50°C at four different concentrations of EB from 0.19 ×10-3 mol/L to 0.33 ×10-3 mol/L, and thus the inflection temperature (Tinf) was in the range of -60°C to -50°C. When [EB] was in the range of 0.24 ×10-3 mol/L to 0.33×10-3 mol/L, Ep was determined to be around -12 kJ/mol when the polymerization was carried out at temperatures from-80°C to Tinf and to be around-28 kJ/mol at temperatures from Tinf to-15°C respectively.

The generalized two-dimensional correlation analysis based on time-resolved light scattering patterns (2D TRLS) has been employed to study the phase separation process of an epoxy-amine-polyethersulfone blend in which the secondary phase separation takes place. The results of the 2D TRLS provided more detailed information that was not readily observed in the 1D TRLS patterns. (i) During the first process of phase separation, the sequential order of coarsening in size of the domains among the larger and smaller ones has been reversed between the diffusion regime and the hydrodynamic regime. (ii) The change of the larger domains in size, due to the hydrodynamic flow in the late stage of the first phase separation process, keeps on taking place earlier than that of the new domains appeared in the secondary phase separation process. (iii) During the secondary phase separation process the size growth of the smaller domains takes place earlier than that of the larger ones, probably due to the assumption that the coarsening mode could decrease the interface tension more quickly.

Based on monomer 2,6,12-triaminotriptycene, hyperbranched polyimides with high molecular weight modified with different terminal functional groups were obtained by polymerization of A2 + B3 system. The prepared hyperbranched polyimides had good solubility in CHCl3, DMF and THF, and performed no detective Tgs in the range of 50-330°C and high Tds (5%) above 455°C.

A relatively high predetermined crystallization temperature (135°C) was chosen to grow well developed iPP spherulites, then the partial melting was carried out at a temperature of 165°C, where the preformed spherulites were seen to only decrease their size but not completely melted. The crystallization behavior of partially melted isotactic polypropylene (iPP) has been carefully examined by different scanning calorimetry (DSC) and polarized light microscopy (PLM). The experimental results show that at a special annealing temperature (165°C) the melting behavior of iPP includes two parts with different mechanism, one part is the melting of iPP spherulite outside, another is the partial lamellae perfection during longer annealing time in the unmelted spherulite. The conformational orders of the iPP melt decrease with the increase of the annealing temperature.

The thermal degradation of poly(arylene sulfide sulfone)/N-methylpyrrolidone (PASS/NMP) crystal solvate was studied by thermogravimetric analysis (TGA) and was compared with pure PASS in order to determine the way in which the formation of the crystal solvate affected the thermal properties of the polymer. The activation energy of the solid state process was determined using Kissinger’s method, which does not require knowledge of the reaction mechanism (RM), to be 174.18 kJ/mol which was lower than that for pure PASS (E = 214 kJ/mol). The study of master curves together with interpretation of integral methods, allows confirmation that the thermal degradation mechanism for PASS in the crystal solvate system is a decelerated Rn type, which is a solid-state process based on a phase boundary controlled reaction, in the conversion range considered. Whereas, the pure PASS follows a decelerated Dn thermodegradation mechanism in the same conversion range.

Mesoporous silica (MS), 3-aminopropyltriethoxysilane (APTES) modified mesoporous silica (AMS), bis(3-trimethoxysilylpropyl)amine modified mesoporous silica (BAMS) and APTES modified solid spherical silica (AS) were prepared and used to immobilize metallocene catalysts for ethylene polymerization. Gel permeation chromatography results showed that polyethylenes (PEs) catalyzed by AMS (or BAMS) supported metallocene catalysts at the molar ratios of Al/Zr = 100, 300 and 500 were of bimodal molecular weight distribution (BMWD); while PEs catalyzed by the above catalysts at the molar ratios of Al/Zr ≥ 800 were of monomodal molecular weight distribution (MMWD). However, MS (or AS) supported metallocene catalysts could only produce PEs with MMWD in spite of the molar ratio of Al/Zr. It was because that AMS (or BAMS) supported catalysts possessed two active sites for ethylene polymerization at low molar ratios of Al/Zr due to the combination effects of mesopore geometrical constraint and amino groups of the supports, which was confirmed by X-ray photoelectron spectroscopy. This brings forward a novel and easy method for the synthesis of polyolefin with BMWD.

A simple and effective way to prepare poly(acrylate)s, such as poly(methacrylate), poly(butyl acrylate) and poly(butyl methacrylate), has been achieved by using the single component aluminum-based compounds, such as modified methylaluminoxane (MMAO), triisobutylaluminium (TIBA) and triethylaluminium (TEA) as initiators. Effective initiations and high molecular weight polymers with unimodal molecular weight distributions could be easily obtained by varying the reaction parameters of systems under mild conditions. Although these aluminum compounds were inefficient initiators for methyl methacrylate (MMA) polymerization, they exhibited remarkable catalytic activity for butyl methacrylate (BMA) polymerization, affording high molecular weight poly(BMA)s.

A brominated hyperbranched polyether has been synthesized from cyanuric chloride and sodium salt of tetrabromobisphenol-A by an A2 + B3 approach. The synthesized polyether was characterized by 1H-NMR, 13C-NMR, UV, FTIR spectroscopy and X-ray diffraction studies, measurements of solution viscosity, molecular weight and solubility and elemental and thermogravimetric analyses. The flame retardancy of the synthesized polyether and its blends with commercially available plasticized poly(vinyl chloride) (PVC) and low density polyethylene (LDPE) was investigated by measurements of limiting oxygen index (LOI) value and thermogravimetric analysis. The properties are compared with a non-halogenated similar type of bisphenol-A based aromatic polyether after blending at different dose levels with the same base polymers. The LOI values of these blends indicated that these hyperbranched polyethers acted as flame retardant additives, and antimony trioxide had prominent synergistic effect with the bromo hyperbranched polyether for the above base polymers, and an increment of 4 to 6 units in LOI values was observed.

Photoinitiated crosslinking of ethylene-propylene-diene terpolymer (EPDM) blends filled with calcium carbonate, talc and calcined kaolin (CK) in the presence of benzil dimethyl ketal as photoinitiator and trimethylolpropane triacrylate as crosslinker and their related properties have been studied by different analytical methods. The results from gel content and heat extension determination show that the efficiency of photocrosslinking of EPDM increases with increasing the content of diene and its molecular weight. The EPDM blends with 100 phr different inorganic fillers can be photocrosslinked to gel content of above 60% by 5 s UV-irradiation under optimum conditions. Under the same conditions of irradiation, the orders of photocrosslinking rate and final gel content are EPDM/CaCO3 EPDM/talc EPDM/CK. The data from thermogravimetric analysis, dynamic mechanical thermal analysis, electrical properties, mechanical tests and scanning electron microscopy show that UV irradiation crosslinking apparently enhances the thermal stability, mechanical properties and electrical properties of the photocrosslinked EPDM/inorganic filler samples. Although the attenuated total-reflection FTIR data show that inorganic fillers can promote the surface photo-oxidation of EPDM/inorganic filler samples with increasing the irradiation time, the above related properties of the photocrosslinked EPDM blends irradiated within 5 s are enough to satisfy many applications in the cable industry.

Acrylonitrile/N-[4-(aminosulfonyl)phenyl]acrylamide (AN/ASPAA) copolymers were synthesized and used as a host of lithium ion conducting electrolytes. The composition, molecular weight and molecular weight distribution of AN/ASPAA copolymers were determined, and the influence of copolymer composition on the glass temperature of AN/ASPAA copolymers and the ion conductivity of electrolytes were investigated. The molecular weights of AN/ASPAA copolymers were lower than those of AN and ASPAA homopolymers due to the cross-termination reaction. The glass temperatures of AN/ASPAA copolymers increased as the molar fraction of ASPAA units in copolymers increased. The lithium ion conductivities of the polymer electrolytes increased initially as the molar fraction of ASPAA units in copolymers increased, and a maximum conductivity was achieved when the molar fraction of ASPAA in the copolymer was 16.8%.