Academic literature on the topic 'Asociace polymerů'

La pertinencia del uso de la contabilidad de gestión ambiental en la toma de decisiones está dirigida a la sostenibilidad de los recursos, sin embargo, las empresas cubanas no consideran en su contabilidad los costos ambientales que generan, ya que aún es limitada la cultura contable asociada al medioambiente y es escasa la base normativa en este sentido. Mayor relevancia ganan las empresas turísticas, que demandan gran consumo de recursos, impactan el medio y a su vez dependen de ellos como atractivos turísticos. La presente investigación tuvo como objetivo general proponer indicadores que permitan medir los costos ambientales derivados de la gestión empresarial del Hotel Roc Presidente. Se aplicaron las técnicas investigativas de análisis documental y de contenido, además de la entrevista, y los datos fueron recolectados de fuentes de información primaria y secundaria. Los resultados obtenidos conllevaron a identificar y describir los aspectos fundamentales de la gestión ambiental del hotel y proponer indicadores afines a dicha gestión que le permitirán a la entidad medir los costos ambientales anuales y tomar decisiones encaminadas a lograr una Gestión Ambiental más eficiente.

Compósitos de polipropileno reciclado (PPr) con harina de madera de la espécie Pinus elliottii (PIE) fueron desarrollados utilizando aceite de soya, ácido esteárico, ácido caprílico y polipropileno graftizado con ácido itacónico (PPgAI) como agentes compatibilizantes. Los compósitos fueron procesados en extrusora de doble husillo co-rotante y posteriormente moldados por inyección. Los materiales fueron caracterizados a través de ensayos mecánicos, termogravimétricos, morfológicos, físicos y por ángulo de contacto. Los resultados de los ensayos mecánicos demostraron que el aceite de soya actuó como plastificante y redujo las propiedades mecánicas de los compósitos. Por otro lado, la adición de ácido esteárico, ácido caprílico y PPgAI generó en un aumento de la resistencia a flexión de 8, 20 y 29%, respectivamente, comparado al compósito sin compatibilizante. El compósito desarrollado con el agente compatibilizante comúnmente utilizado, el polipropileno graftizado con anhidrido maleico (PPgAM), presentó un aumento de 35% en la resistencia a la flexión. Resultados del análisis termogravimétrica (TGA), del compósito de PPr con aceite de soya presentó una reducción de su estabilidad térmica en 3% de pérdida de masa, lo que puede estar asociado a la mayor cantidad de oxígeno en su estructura molecular, lo que facilita mayor movilidad de las cadenas con el aumento de la temperatura y que pueden acelerar el proceso de degradación. En el caso de los compósitos con ácido caprílico y PPgAI mostraron un aumento superior a 10°C en la temperatura de 3% de perda de masa cuando comparados al compósito sin compatibilizante, indicando un aumento de la estabilidad térmica de estos compósitos. Los resultados de los análisis de microscopia electrónica de Barrido comprobaron la mayor interacción entre las fases (harina de madera y la matriz de PPr) para los compósitos desarrollados con ácido caprílico y PPgAI; y en relación a los resultados del ángulo de contacto de los materiales, mostraron que la incorporación del agente compatibilizante graftizado originó un aumento de la energía superficial de la matriz polimérica promoviendo una mejor interacción con la carga vegetal (hidrofílica). Palabras clave.-.- Madera plástica, Reciclaje mecánica, Agente compatibilizantes, Harina de madera. ABSTRACTWood plastic composites of recycled polypropylene PPr and Pinus elliottii (PIE) were developed using soybean oil, stearic acid, caprylic acid and itaconic acid grafted with polypropylene (PPgAI) as coupling agents. The composites were processed in a co-rotating twin screw extruder and injection molded. The materials were characterized by mechanical properties, thermogravimetric analysis, morphological, physical and contact angle. The results showed that soybean oil acted as a plasticizer and reduced mechanical properties of composites. On the other hand, the addition of stearic acid, caprylic acid and PPgAI resulted in an increase in flexural strength of 8, 20 and 29%, respectively, when compared to the composite without compatibilizer. The composites developed with coupling agent commonly used, polypropylene grafted with maleic anhydride (PPgAM) had a 35% increase in flexural strength. TGA results showed that the composite with soybean oil showed a reduction of thermal stability by 3% mass loss, which may be associated with more oxygen in their molecular structure and promote greater mobility of the polymer chains with increase the temperature and which may accelerate the degradation process. Composites with caprylic acid and PPgAI showed an increase above 10 ° C in temperature of 3% mass loss when compared to the composite without compatibilizer. SEM analysis showed the greater interaction between the wood flour and PPr for composites developed with PPgAI and caprylic acid. The results of contact angle showed that the incorporation of a PPgAM caused an increase in surface energy of the polymer matrix which may promote better interaction with hydrophilic wood flour. Keywords.- Wood plastic composites, Mechanical recycling, Coupling agent, Wood flour.

Title: Self-assembly of polymers with amphiphilic compounds (surfactants) in aqueous solutions Abstract: This PhD Thesis is devoted to the co-assembly in systems containing electrically charged polymers (polyelectrolytes and block copolymers containing polyelectrolyte sequences). I studied the interactions between block copolymers and oppositely charged surfactants in aqueous solutions, and the structure and properties of co-assembled nanoparticles by a combination of several experimental methods. I found that the spontaneous formation, solubility and stability of complex nanoparticles depend not only on the electrostatic attractive forces but also on the hydrophobic effects. In a major part of my Thesis, I studied the interaction of polyelectrolytes with oppositely charged gemini surfactants (containing two charged head-groups interconnected by a short linker and two hydrophobic tails) which is a relatively new topic - much less studied than the co-assembly with conventional single tail surfactants. Better understanding of the formation and properties of complexes containing gemini surfactants and polymers provides knowledge that should lead to novel tailor-made nanoparticles with desired properties for applications in medicine and new technologies (including nano-technologies). We have shown that the...

The Thesis describe my studies based on self-assembly and co-assembly of block copolymer micelles that I conducted at the Department of Physical and Macro- molecular Chemistry at the Charles University, Prague in the research group of my supervisor, Prof. Dr. Karel Procházka, DrSc. The Thesis based on my publications and consists of four parts. Here I studied the formation of polymeric nanoparticles in aqueous solutions formed by polyelectrolytes with hydrophobic backbones by a combination of several experimental methods. The achieved results enabled me to explain the structure and properties of studied self- and co-assembled nanoparticles and to outline the decisive trends of their behavior. The spontaneous formation, sol- ubility and stability of complex nanoparticles depend not only on the electrostatic attractive forces but also on the hydrophobic effects. As the enthalpy-to-entropy interplay is very complex, a number of external factors such as temperature, pH, salinity and concentration affect the assembling process and structure of formed nanoparticles. 1

In this work, copolymers of celulose-g-polystyrene (cel-PS) and celulose-g- poly(methylmetacrylate) (cel-PMMA) were characterized using static and dynamic light scattering, transmission electron microscopy and atomic force microscopy. Preparation of nanoparticles of these hydrophobic copolymers in aqueous solution was further studied, by means of precipitation from dioxane solutions using water with added low-molar-mass surfactants sodium dodecylsulfate (SDS) and dodecyltrimethylammonium bromide (DTMAB). It was shown that the ability of the surfactants to stabilize polymer nanoparticles is driven not only by the hydrophobic effect, but it depends also on specific interactions of the polar group of the surfactant with the surface of the nanoparticles. On the basis of the finding that the efficiency of stabilization of cel-PS copolymers is much higher than in case of linear PS, it can be concluded, that the branched structure of copolymers is favorable for the formation of hydrofobically stabilised polymer-surfactant complexes.

Title: The study of the association behaviour of the amphiphilic copolymers in solutions containing low molar compounds by means of computer simulations. Author: Mgr. Karel Šindelka Department: Faculty of Science, Charles University Supervisor: Doc. Ing. Zuzana Limpouchová, Csc. Abstract This doctoral thesis focuses on the study of electrostatic self- and co-assembly in complex polymer solutions containing polyelectrolyte (PE) block copolymers together with surfactants, neutral homopolymers, or oppositely charged PEs using the dissipative particle dynamics (DPD). It was shown that the electro- static self-assembly depends not only on the cooperative interactions of oppo- sitely charged PE chains, but also on the amphiphilicity of PE species or on the polymer block compatibility, among other properties. PEs with incompatible blocks create well-defined core-shell structures, while large ill-defined crew-cut aggregates form from PEs with compatible blocks In non-stoichiometric mixtures of PEs with incompatible blocks, co-assembled nanoparticles are smaller than in stoichiometric mixtures and are charged. The destabilization of larger aggregates depends on how the PE charge surplus is introduced: the effect is strongest when the density of the surplus PE charge on the PE chains is increased and weakest when the...