دو ماهنامه علوم و تکنولوژی پلیمر
سال بیست و دوم شماره 6 (پیاپی 104، اسفند 1388)

Nanocomposites based on phenolic resol and novolac resins and Cloisite 30B were prepared. Different kinds of phenolic resins and clay content were studied with respect to the morphology and mechanical properties of the polymer silicate layers. The phenolic resins, namely resol, novolac and their mixture and four different percentages of clay contents, 0.5, 1, 2 and 5 wt% have been considered. XRD analysis has been used to investigate clay distribution in the prepared polymer matrices. Chopped strand mat glass fiber was impregnated with each phenolic resin solution and after hand-lay-up, specimens were prepared by hot press compression molding. The mechanical properties of the nanocomposites were assessed by tensile, flexural and Izod impact tests. XRD results show that the degree of clay distribution in resol type phenolic resin is more satisfactory than novolac resin. Based on mechanical properties evaluations, the novolac nanocomposites showed better mechanical properties than other systems under study. The mixture of novolac resin and resol showed improved mechanical properties relative to each phenolic system. The final results indicate that nanocomposites with 2 wt% clay content show maximum modulus and tensile strength increased by 23%. Impact test results also show that optimum properties can be achieved with 2 wt% clay content.

Some formulations of drug in adhesive transdermal drug delivery systems ()TDDSs)(with different functional and non-functional acrylic pressure sensitive adhesives PSAs)(were prepared. For this purpose fentanyl was used as a drug component. The effects of PSAs type on skin permeation and in vitro drug release from devices were evaluated using hydrodynamically well-characterized Chien permeation system fitted with excised rat abdominal skin. The adhesion properties of devices ()peel strength and tack values)(were obtained. It was found that TDDS with –COOH functional PSA had the lowest steady state flux. Drug release was followed by Higuchi's kinetic model. Adhesion properties of the samples were improved by addition of functional PSA in the formulations.

Ethylene bis-stearamide is one of the important acrylonitrile-butadiene-styrene ()ABS)(polymer additives, which is used as lubricant, slip agent and mold release agent. In this research, ethylene bis-stearamide for ABS application was synthesized using stearic acid and ethylene diamine under reflux condition. Refluxing prevented ethylenediamine from evaporation and thus the initial molar ratio was maintained unchanged. The other role of refluxing was to prevent the oxidation of ethylene diamine by removal of oxygen which might have been present inside the reactor. The synthesized samples were characterized by Fourier transform infrared spectroscopy ()FTIR)(, total acid number and melting point. The total acid number of the synthesized samples in the lab, bench scale 1 kg)(and pilot scale 30 kg)(were 6.5, 8.7 and 8.6 mgKOH/g, respectively, and their melting points were in 141-144 °C range. It was found that total acid number values of samples are inversely proportional with reaction time. The longer the reaction time, the higher was the total acid number and sample purity. Compounding was carried out using ABS containing synthesized and reference ethylene bis-stearamide and the physical-mechanical properties of the samples were measured. The obtained results showed that, the measured properties such as melt flow index, impact resistance, softening temperature, heat deflection temperature, tensile strength and hardness for the compound prepared using synthesized ethylene bis-stearamide match very well with those of reference compound.

In this study, the effect of hydrocarbon and rosin ester resins combination on the physical and mechanical properties of thermoplastic road markings were evaluated. At first, two basic thermoplastic road marking formulations based on hydrocarbon and rosin ester resins were prepared. Several samples of the blends of two basic formulations for thermoplastic road marking were characterized and compared by their softening points, abrasion resistance, color data changes, DMTA and tensile strength values. The results showed that hydrocarbon-based thermoplastic road markings have better weathering resistance and rosin ester based materials illustrated enhanced heat resistance. The inclusion of rosin ester thermoplastic road marking into the hydrocarbon-based formulations, improves compatibility of the hydrocarbon resin and dibutyl phthalate ()DBP)(, as well as their physical and mechanical properties. The unique properties of rosin arise from its hydrophobic chain skeleton and its hydrophilic carboxy groups which contribute to its excellent solubility and compatibility with a variety of other synthetic resins. The best performance was obtained with 50 wt % inclusion of rosin ester to hydrocarbon based compound. DMTA analysis revelation with combination of hydrocarbon and rosin ester-based road markings showed that the decreasing trend in elastic modulus is shifted to higher temperature, and as a result it keeps the hardness and ductile properties of thermoplastic road markings unchanged. More favored raw materials for compatibilization of compounds in road marking formulations lead to higher elongation- at-break and an increased toughness.

A new method was used to prepare ABS/PA6 blends by in situ polymerization and compatibilization method. In this process, ε-caprolactam monomer was polymerized in presence of ABS via activated anionic polymerization to produce PA6. The main ingredients of the reaction mixture included: monomer ()ε-caprolactam), catalyst Na-caprolactamate), microactivator HDI)(and macro-activator SMA)(. Then, in different steps caprolactam/ABS composition, micro-activator and macro-activator concentrations were selected as the variables. ABS/PA6 blends were prepared in an internal mixer at 200°C)(at three levels of ABS/caprolactam compositions ()25/75, 50/50, 75/25)(, with varied concentrations of HDI 4 and 6 phc)(and macro-activator 0, 3 and 6 phc)(. As a result of all the variations the blends produced different morphologies.In samples with dispersed structure, the particle size reduced with higher macro-activator content. Also, the effect of macro-activator at lower level of HDI was more significant, probably due to the competition between the activators in the reaction. In some of the blends, dispersed particles with sizes under 100 nm were observed. The crystalline structure of PA6 phase was investigated using XRD and DSC tests, which also showed changes with regard to initial composition and activator contents. In pure samples only α-structure was detected, while in the blends of higher ABS content, γ-form appeared and at the ABS content of 75% only γ-form was observed. The crystallinity decreased as the function of ABS content. Pure synthesized PA6 showed higher Tm and Hc than the blends. The percentage crystallinity of the samples obtained from XRD and DSC tests showed good correlation.

Water soluble amphoteric graft copolymers of polysaccharide were synthesized via grafting of cationic monomer onto the sodium carboxymethylcellulose ()CMC)(and then used as a shale stabilizer in the water-based drilling fluids. Accordingly, five types of CMC-graft copolymers with different ratios of acrylamide AM)(and diallyldimethylammonium chloride DADMAC)(were synthesized. Grafting of monomer()s)(onto the CMC was verified by FT-IR spectroscopy. Results showed that grafting percentage is strongly affected by the monomer type as well as the weight ratio of monomers. Synthesized CMC-graft copolymers were used in the formulation of water-based drilling fluid. Drilling fluid was then subjected to the rheological, fluid loss and shale recovery tests. It was found that ability of CMC in the shale stability enhances by grafting of cationic monomer onto CMC. Fluid loss is also controlled in the acceptable region in the presence of CMC-graft copolymers. Among graft copolymers, CMC-grafted with pure cationic monomer exhibited higher efficiency in the fluid loss control and more important in the shale stability.

In this study, doxycycline hyclate release behavior from in situ forming drug delivery systems investigated. These systems based on poly(lactide-co-glycolide) 50:50 dissolved in N-methyl-2-pyrrolidone that were evaluated in different concentrations. These systems are useful for local treatment of periodontal diseases. UV spectroscopy is used to determine drug concentration in release medium. Also, a new method to stabilize drug in release medium was developed. The structure of prepared membranes is explained by scanning electron microscopy (SEM) to evaluate the surficial and cross-sectional structures of polymer matrices. With increasing in polymer concentration, surface porosity decreased, membrane structure became denser, burst decreased and drug release time increased.