We report the development of copolymers based on 2-vinylpyridine with different porosity degrees. The copolymers were quaternized with methyl iodide and acrylonitrile to introduce quaternary ammonium groups on pyridine units. To prepare charge transfer complexes, the unmodified copolymers and their derivatives quaternized were impregnated with iodine. The antibacterial properties of all the polymers were evaluated ranging from of the Escherichia coli strain. The unmodified copolymers did not have antibacterial activity against E.Coli suspensions. The quaternization with methyl iodine and acrylonitrile increased the biocidal performance of these copolymers, but only the copolymer with the lowest porosity modified with methyl iodine showed significant bactericidal action for all E. Coli concentrations. The 2-vinylpiridine copolymers quaternized and impregnated with iodine had higher antibacterial activity than the impregnated ones. The charge transfer complexes derived from the copolymer with the lowest porosity and highest swelling capacity in water had the best bactericidal performance.

We report the development of two copolymers based on 2-vinylpyridine, styrene and divinylbenzene (2Vpy-Sty-DVB) with different porosity degrees. The copolymers were subsequently quaternized with methyl iodide. To prepare charge transfer complexes, the unmodified copolymers and their derivatives quaternized with methyl iodine were impregnated with iodine. The antibacterial properties of the polymers were evaluated in dilutions ranging from 10² to 10(7) cells/mL of the auxotrophic OHd5-K12 Escherichia coli strain. It was possible to obtain materials with complete antibacterial activity even in the highest cell concentrations tested.

This paper describes the preparation of magnetic copolymer obtained from suspension polymerization of styrene (Sty) and divinylbenzene (DVB) in the presence of iron particles treated and not treated with oleic acid. The magnetic copolymers were characterized according to their morphology, particle size distribution and magnetic properties. The results show that incorporation of iron particles significantly changed the particles’ morphology. All samples presented higher saturation magnetization than the values reported in the literature and the particle size distribution was more monodisperse when the polymerization was conducted with 5%wt of benzoyl peroxide (BPO).

This review deals with the homo- and copolymerization of styrene with nickel catalysts. The catalytic activity, polymer stereoregularity, polymer molecular weight and polydispersity are dependent upon nickel ligands and reaction parameters. Catalysts supported on silica, treated with methylaluminoxane (MAO), have shown higher stereospecificity and activity compared to homogeneous ones. The influence of these parameters is discussed focusing on the elucidation of some aspects of the polymerization mechanism.

Foi estudado um processo de polimerização de butadieno, em escala de laboratório, para obtenção de polibutadieno com alto teor de unidades repetitivas 1,4-cis, utilizando-se o sistema catalítico do tipo Ziegler-Natta constituído por versatato de neodímio (Nd), cloreto de tert-butila (Cl) e um composto organoalumínio (Al). Foi estudada a influência do tipo de organoalumínio, da razão molar Al/Nd e Cl/Nd sobre a atividade catalítica do sistema, peso molecular, polidispersão e microestrutura do polibutadieno obtido (teor de unidades 1,4-cis). Os polímeros foram caracterizados por espectroscopia na região do infravermelho e cromatografia por exclusão de tamanho. Foi obtido um polímero com até 99,8% de unidades 1,4-cis. O peso molecular Mw variou de 1,4 a 9,7 x 10(5) e a atividade catalítica máxima foi conseguida quando se empregou triisobutilalumínio (TIBA) como cocatalisador.

In this work a laboratory scale process was studied for the production of polybutadiene with high content of cis-1,4 repeating units utilizing a three-component Ziegler-Natta catalyst system of neodymium versatate (Nd)/tert-butyl chloride (Cl)/aluminum alkyl compound (Al) in n-hexane. The influence of the aluminium alkyl type, Al/Nd and Cl/Nd molar ratios on the catalyst activity, polybutadiene molecular weight characteristics and polybutadiene microstructure (cis 1,4 content) was studied. The polymers were characterized by infrared spectroscopy and size exclusion chromatography. A polymer with 99.8% of 1,4-cis units was produced. The molecular weight varied from 1.4 to 9.7 x 10(5), and maximum catalyst activity was achieved when triisobutylaluminium (TIBA) was used as cocatalyst.

A estrutura de cada polímero tem influência direta sobre a sua densidade e suas propriedades mecânicas. Ramificações longas, como as presentes no polietileno de baixa densidade, por exemplo, aumentam a resistência ao impacto, diminuem a densidade e facilitam o processamento, enquanto que as ramificações curtas, presentes no polietileno linear de baixa densidade, aumentam a cristalinidade e a resistência à tração em relação ao polietileno de baixa densidade (obtido via radicais livres). As principais aplicações, assim como o tipo de processamento usado para cada tipo de polietileno, são apresentadas neste trabalho. Por último, é feita uma comparação entre catalisadores Ziegler-Natta e catalisadores metalocênicos. O polietileno produzido por catalisador metalocênico apresenta uma estreita distribuição de peso molecular e uma distribuição mais uniforme de comonômeros incorporados às cadeias poliméricas do que o polietileno produzido por catalisadores Ziegler-Natta. Essas características propiciam uma melhora na resistência à tração do produto final.

The structure of each polymer has a direct influence on its density and mechanical properties. Long-chain branches, such as those present in low density polyethylene, for example, increase its impact strength, decrease density and improve processing. Short-chain branches present in linear low density polyethylene, on the other hand, increase crystallinity and tensile strength in comparison to low density polyethylene (produced by free radical initiators). The main applications and the type of processing used for each type of polyethylene are also presented in this work. A comparison between Ziegler-Natta and metallocene catalysts is carried out. The polyethylene produced by metallocene catalysts presents narrow molecular weight distribution and a uniform distribution of comonomer incorporated into the polymer chain. Those characteristics provide an enhancement on the tensile properties and impact strength of final products.

O presente trabalho teve por objetivo avaliar as propriedades mecânicas, térmicas e morfológicas de sistemas à base de poliolefinas (PP e HDPE) e copolímero metalocênico de etileno/1-octeno (EOC), produzido pela Dow Chemical. Foi também investigada a atuação de um copolímero metalocênico de propileno/1-octeno (POC), sintetizado em laboratório, como agente compatibilizante da mistura PP/EOC. Os resultados mostraram que a adição de teores específicos de EOC ao HDPE e PP pode levar à produção de materiais com boas propriedades mecânicas. Os dados obtidos também revelaram que o copolímero POC pode ser usado como agente compatibilizante das misturas PP/EOC.

The aim of this work was to evaluate the mechanical, thermal and morphological properties of systems based on polyolefins (PP and HDPE) and ethylene/1-octene metallocene copolymer (EOC), produced by Dow Chemical. The effect of a propylene/1-octene metallocene copolymer (POC), obtained in the laboratory was also investigated as a compatibilizer agent for the PP/EOC blend. The results showed that the addition of certain contents of EOC to PP and HDPE may carry the production of materials with good mechanical properties. The data obtained also revealed that the POC copolymer can be used as compatibilizer agent of the PP/EOC blends.