ABSTRACT
An efficient and smart synthesis of bis-α-ketoamides has been disclosed. The desired products have been obtained through a Passerini multicomponent reaction using biobased aldehydes, acetic acid and bis-isocyanides (prepared from the corresponding biobased diamides), followed by a deprotection/oxidation step. The effect of the synthesized compounds on the crystallization behavior of poly(l-lactide) (PLLA) has been investigated by differential scanning calorimetry (DSC) in non-isothermal conditions. Among all the synthesized compounds, only a few are able to meaningfully enhance the nucleation of PLLA, as confirmed by a shift of the polymer crystallization peak temperature towards higher values. With the research of active polymer nucleating agents being mostly empirical, the combinatorial synthetic approach proposed herein, coupled with the possibility of a small scale mixing procedure, can potentially represent a useful strategy for the discovery of new efficient biobased polymer additives.
ABSTRACT
Titanium dioxide (TiO2) nanoparticles have recently appeared in PET waste because of the introduction of opaque PET bottles. We prepare polymer blend nanocomposites (PBNANOs) by adding hydrophilic (hphi), hydrophobic (hpho), and hydrophobically modified (hphoM) titanium dioxide (TiO2) nanoparticles to 80rPP/20rPET recycled blends. Contact angle measurements show that the degree of hydrophilicity of TiO2 decreases in the order hphi > hpho > hphoM. A reduction of rPET droplet size occurs with the addition of TiO2 nanoparticles. The hydrophilic/hydrophobic balance controls the nanoparticles location. Transmission electron microscopy (TEM_ shows that hphi TiO2 preferentially locates inside the PET droplets and hpho at both the interface and PP matrix. HphoM also locates within the PP matrix and at the interface, but large loadings (12%) can completely cover the surfaces of the droplets forming a physical barrier that avoids coalescence, leading to the formation of smaller droplets. A good correlation is found between the crystallization rate of PET (determined by DSC) and nanoparticles location, where hphi TiO2 induces the highest PET crystallization rate. PET lamellar morphology (revealed by TEM) is also dependent on particle location. The mechanical behavior improves in the elastic regime with TiO2 addition, but the plastic deformation of the material is limited and strongly depends on the type of TiO2 employed.
ABSTRACT
En este trabajo fueron estudiados los productos obtenidos por la funcionalización de copolímeros de etileno-alfa-olefina, que poseían varios comonómeros (1-buteno, 1-hexeno), con diferentes agentes (dietilmaleato, anhídrido maléico, monoitaconato de decilo y acrilamida). Todas las funcionalizaciones fueron realizadas en disolución. La introducción de los agentes funcionalizantes se confirmó por el uso de la espectroscopia infrarroja con transformada de Fourier (FTIR). El fraccionamiento térmico de los productos se realizó utilizando la calorimetría diferencial de barrido (DSC) y la aplicación de la técnica de autonucleación y recocidos sucesivos (SSA). La morfología y los detalles lamelares fueron investigados por observación en el microscopio electrónico de transmisión (TEM) de muestras teñidas por clorosulfonación. Los estudios de fraccionamiento revelaron diferencias entre los productos en cuanto a su comportamiento de fusión. En algunos productos la cantidad de las reacciones colaterales fue mayor que en otros. Los estudios microscópicos confirmaron que la introducción de agentes funcionalizantes dio lugar a la presencia de espesores lamelares más delgados
