To explore the relationship between the properties of the PTFE micropowders and the irradiation conditions, several PTFE micropowders were prepared by electron beam irradiation from 5 to 4000 kGy in air at room temperature. The properties of the irradiated PTFEs were characterized by particle size and its distribution (PSD) determination, differential scanning calorimetric (DSC) and thermogravimetric (TG) analysis, melt flow rate (MFR) and contact angle (CA) measurements. The results indicate that the particle size, the melting and crystallization temperature (Tm and Tc) and the melt viscosity of the irradiated PTFE are lower (smaller) than those of the pristine PTFE. By linear regression, the correlation between Tm (or Tc) of the PTFE micropowder and irradiation dose is established. The variation of surface properties of the irradiated PTFE micropowder is also reported.

To increase the molecular weight of poly (phenylene sulfide ether) (PPSE), a novel route has been developed via the reduction of poly (phenylene sulfoxide ether sulfide ether) (PPSOESE) precursor. The synthesis of high molecular weight PPSOESE is essential for the ultimate purpose. Effects of process parameters on preparation of PPSOESE were firstly investigated and the optimization was performed by response surface methodology (RSM). Average number molecular weight (Mn) and Yield of PPSOESE were defined as the experimental responses. The statistical analyses indicate that the most significant factor is monomer concentration, followed by reaction temperature and the interaction of reaction temperature • monomer concentration. Under optimal conditions, the and Yield responses were obtained as 1.78 ×104±1.02 % and 93.6±1.3 %, which are in agreement with the predicted values of 1.80 ×104and 95.4 %, respectively. Structure of PPSOESE was also characterized. The highest intrinsic viscosity and yield of PPSE by the reduction of PPSOESE reached to 0.78 dL/g and 93.2%, respectively, much greater than the reported results. The work is helpful for forthcoming preparation and study of high molecular weight PPSE.

In order to reuse the waste originated from poly(phenylene sulfide) (PPS) production in stead of combustion, the oligomeric materials in the waste were recovered as raw materials. The recovered materials, then, were used to react with sulfur in molten state to produce polymeric resin. The structure and thermal property of oligomeric materials and their derived polymer were characterized by elemental analysis, infrared spectroscopy, X-ray diffraction and differential scanning calorimetry. The results showed that oligomeric materials are a series of PPS oligomers, and their derived polymer is poly(arylene sulfide)s (PAS). The thermal transition temperatures of obtained PAS are higher than those of PPS oligomers, which are attributed to the increase of molecular weight. It is desired that the yielding PAS has potential applications as plastic, coating, or filler materials.

The polycondensation kinetics of 4,4’-dihydroxydiphenyl sulfide (DHPS) with 4,4’-dichloro diphenylsulfide (DCPS) was investigated in the presence of catalyst 2A. The reaction follows second-order kinetics and the reaction rate is a bimodal, a relatively lower rate initially and a faster rate after 3h. The initially lower rate is attributed to the lower solubility of DHPS salt in organic solvent. The results show higher polymerization temperature leads to higher conversion and finial reaction extent after 7h. In the present work, catalyst 2A/DHPS molar ratio of 0.17 is considered more suitable for PPSE preparation. The activation energy of two-stage polymerization of PPSE is 104.5kJ/mol and 79.33kJ/mol, respectively. According to obtained kinetics parameters, curves of fractional conversion versus reaction time were simulated and compared with experimental curves at different temperatures.