SYNOPSISPoly(viny1 chloride) (PVC), PVC/chlorinated polyethylene (CPE), PVC/oxidized polyethylene (OPE), and PVC/CPE/OPE compounds were prepared in a Haake torque rheometer at various temperatures, rotor speeds, and totalized torques (TTQ). The fusion characteristics of these PVC compounds (fusion time, fusion torque, and fusion temperature) were studied. Longer fusion time results in higher fusion temperature. Higher fusion temperature results in lower fusion torque. The fusion time of PVC/OPE compounds is the longest among these PVC blends. However, the fusion time of PVC/CPE/OPE compounds is the shortest among these PVC blends. The fusion time of the PVC/CPE/OPE compound is significantly different from those of PVC, PVC/OPE, and PVC/CPE compounds at the medium starting temperature and the medium rotor speed. Scanning electron microscopy (SEM) analyses successfully revealed the surface morphological changes of the fusion of PVC, PVC/OPE, PVC/CPE, and PVC/CPE/OPE compounds. The lubrication mechanisms of these PVC compounds have also been postulated. 0 1995 John Wiley & Sons, Inc. I NTRO DUCT10 NPoly(viny1 chloride) (PVC) was first found and characterized more than 120 years ago, but, due to its poor thermal stability, making processing diEcult, it was not until about 1930 that people began producing commercial PVC products.' To overcome its poor thermal stability and photochemical degradation, researchers developed suitable stabilizer systems,' heat stabilizers (e.g., lead compounds, organotin compounds, and other metal compounds), and light stabilizers ( e.g., phenyl salicylate, oxalic anilide, and phenyl formamidine) to solve these problems and PVC is now one of the world's highestvolume synthetic polymers.Chlorinated polyethylene (CPE) is commonly used as an impact modifier of PVC. The CPE used as impact modifiers in PVC are produced by chlorinating high-density polyethylene in aqueous ~l u r r y .~The chlorine distribution and chlorine content of CPE are major factors in the mixing of CPE

ABSTRACT:The glycolysis of recycled poly(ethylene terephthalate) flakes by ethylene glycol (EG) is investigated. Bis-2-hydroxyethyl terephthalate (BHET) and oligomers are predominately glycolysis products. The influences of glycolysis temperature, glycolysis time, and the amount of catalyst (cobalt acetate) are illustrated. The BHET, dimer, and oligomers are predominately glycolysis products. The optimum glycolysis temperature is found to be 190°C. If a 190°C glycolysis temperature, 1.5-h glycolysis time, and 0.002 mol glycolysis catalyst (cobalt acetate) are used, the glycolysis conversion is almost 100%. The glycolysis conversion rate increases significantly with the glycolysis temperature, glycolysis time, and the amount of cobalt acetate. Thermal analyses of glycolysis products are examined by differential scanning calorimetry. In addition, the chemical structures of glycolysis products are also determined by a Fourier transform IR spectrophotometer.

SYNOPSISRigid poly(viny1 chloride) (PVC) compounds were prepared in a Haake torque rheometer using various blending conditions. The fusion levels of processed compounds were evaluated by a capillary rheometer and differential scanning calorimetry (DSC), based on the entrance pressure drop and the heat of fusion, respectively. S-shaped fusion curves were obtained. Starting temperature of the mixer, rotor speed, and totalized torque are the three major factors that affect the fusion level of PVC compounds blended in the Haake torque rheometer. All three parameters have a significant effect; however, totalized torque has the greatest effect and this can be characterized using a torque rheometer. Both capillary rheological and DSC thermal analysis can be applied to determine the fusion level of a PVC compound. The morphological changes of the various fusion processes were characterized by scanning electron microscopy (SEM). crystallinity. To achieve good mechanical properties, grain boundaries must be eliminated and the microparticles must be altered and compacted together. After significant interdiffusion, the boundaries of submicroparticles disappear, and a three-dimensional network of polymer chains is formed. This is referred to as the fusion, or gelation, of poly(viny1 chloride) (PVC) -2,3 Benjamin4 reported that a PVC product with the fusion level between 60 and 80% has an optimum value of impact ductility.

Rigid poly(vinyl chloride) (PVC), PVC/chlorinated polyethylene (CPE), and PVC/CPE/oxidized polyethylene (OPE) compounds were prepared in a Haake torque rheometer. The fusion percolation thresholds (FPTs) of these compounds were defined and compared. Moreover, the fusion curves of these compounds were illustrated and compared. A higher processing temperature resulted in a shorter fusion time and a lower FPT. For PVC/CPE compounds, a higher concentration of CPE could decrease the FPT and promote PVC particles to fuse together easily. Meanwhile, in the beginning of the fusion process, the interaction between a higher concentration of OPE and calcium stearate in PVC/OPE compounds could also promote an easy fusion of the PVC particles. For PVC/CPE/OPE compounds, the synergistic interaction among CPE, OPE, and calcium stearate resulted in the shortest fusion time and the lowest FPT. The FPTs of rigid PVC samples were strongly dependent on not only the processing conditions but also the formulations of the samples.

Efficient gene delivery technologies play an essential role in the gene functional analyses that are necessary for basic and applied researches. Mosquitoes are ubiquitous insects, responsible for transmitting many deadly arboviruses causing millions of human deaths every year. The lack of efficient and flexible gene delivery strategies in mosquitoes are among the major hurdles for the study of mosquito biology and mosquito-pathogen interactions. We found that Autographa californica multiple nucleopolyhedrovirus (AcMNPV), the type baculovirus species, can efficiently transduce mosquito cells without viral propagation, allowing high level gene expression upon inducement by suitable promoters without obvious negative effects on cell propagation and viability. AcMNPV transduces into several mosquito cell types, efficiently than in commonly used mammalian cell lines and classical plasmid DNA transfection approaches. We demonstrated the application of this system by expressing influenza virus neuraminidase (NA) into mosquito hosts. Moreover, AcMNPV can transduce both larvae and adults of essentially all blood-sucking mosquito genera, resulting in bright fluorescence in insect bodies with little or no tissue barriers. Our experiments establish baculovirus as a convenient and powerful gene delivery vector in vitro and in vivo that will greatly benefit research into mosquito gene regulation, development and the study of mosquito-borne viruses.