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Carlos A. Ararat,Winston Quiñonez,Edwin A. Murillo 한국고분자학회 2019 Macromolecular Research Vol.27 No.7
The aim of this work is to obtain the material that, in the future, may become a better alternative, as a functionalizing agent, to maleic anhydride (MA), or a crosslinking agent with the least amount of functional groups. To achieve that goal, a hyperbranched polyester polyol (HBP) of the second generation (HBP2G) was modified with MA to obtain HBP2GMA. The effects of the proportion of MA in the structural, thermal, and rheological properties of the HBP2GMAs were evaluated. Furthermore, these properties were compared with those of the HBP2G. A reduction in the intensity of peak corresponding to the OH stretching of HBP2G was observed with the increase in the extent of HBP2G modification by the analysis of the infrared (IR). HBP2GMAs showed a peak at 3030 cm-1 in their IR spectra, which was due to the -CH=CH- stretching of MA. This was further assessed by 1H NMR analysis. The number of MA units grafted into HBP2G was between 4 and 9, indicating a high degree of functionality. All materials possessed viscosity values below 34.94 Pa·s at 110 °C, which were dependent on the grade of the modification percentage (MP) and the molar content of MA grafted into HBP2G. Mass spectrometry analysis demonstrated the formation of products by the esterification reaction between the HBP2G and MA. The thermal stability of the HBP2GMAs determined as the decomposition temperature (Td) was between 258 and 281 °C which was better than that of the HBP2G.
Carlos A. Ararat,María Judith Percino,Edwin A. Murillo 한국고분자학회 2020 Macromolecular Research Vol.28 No.3
Low density polyethylene (LDPE)/polyamide6 (PA) blends can lead to a synergy between the properties of these materials. These blends are employed mainly in the packing industry, especially in food factories. The problem of this system is that it is inmiscible, hence requires to be compatibilized. The aim of this study is to compatibilize blends of LDPE/PA6 using a LDPE modified with a maleinized hyperbranched polyol polyester (LDPE-g-MHBP) as a compatibilizing agent. Therefore blends of LDPE (50 wt%)/PA (50 wt%) were prepared by using proportions of 5 (Blend5), 10 (Blend10), 15 (Blend15) and 20 (Blend20) wt% of the LDPE-g-MHBP of the total mix. On the other hand, to determine the efficiency of the LDPE-g-MHBP as a compatibilizing agent, a Blend0 (blends of LDPE (50 wt%)/PA (50 wt%) without LDPE-g-MHBP) was used as the control sample. By infrared (IR) analysis was evidenced the interactions between PA and LDPE-g-MHBP. By differential scanning calorimetry analysis (DSC) was observed that the LDPE-g-MHBP increased the crystallinity of the LDPE phase, but the behavior was opposite to PA. The thermal stability and the viscosity of the blends obtained with LDPE-g-MHBP were higher than those of the Blend0. Scanning electron microscopy (SEM) analysis revealed that the LDPE-g-MHBP ostensibly improved the miscibility of the LDPE/PA blends.
Edwin A. Murillo,Margarita Cerón,M. Judith Percino 한국고분자학회 2021 Macromolecular Research Vol.29 No.4
The present study sought to obtain a hyperbranched polyester polyol derivative with fluorescent properties. Initially, a 4-((4-(9H-carbazol-9-yl)benzyl)oxy)- 4-oxobut-2-enoic acid (CAV) was synthesized and esterified with a hyperbranched polyester polyol obtained from fourth generation (HBP) to synthesize carbazolebased hyperbranched polyester polyols (HBPCAV). The proportions employed of CAV were 5, 10, 15, and 20 wt% relative to that of HBP. The grafted CAV percentage (P gCAV) increased with the CAV content. The conversion percentages (CP) of the reactions for obtaining HBPCAV were higher than 95% and the hydroxyl values (OHV) were lower than that of HBP. The modification percentage (MP) of the HBP was between 9.33 and 27.38%. Using proton nuclear magnetic resonance (1H NMR) and infrared (IR) analyses was evidenced the formation of CAV and HBPCAV. Dynamic light scattering (DLS) analysis showed that HBPCAV exhibited aggregations. The number average molar mass (M n), viscosity (η), and glass transition temperature (T g) values of the HBPCAV samples were higher than those of the HBP, and also increased with the P gCAV values. The rheological behaviors of the HBP and HBPCAV samples were mainly Newtonian and shear-thinning, respectively. All HBPCAV exhibited electroluminescent properties.
In situ compatibilization of thermoplastic starch/polylactic acid blends using citric acid
Edwin A. Murillo 한국고분자학회 2023 Macromolecular Research Vol.31 No.2
In this study, in situ compatibilized thermoplastic starch (TPS)/polylactic acid (PLA) blends were obtained using citric acid (CA) as promoter of compatibilization. The TPS (60 wt%)/PLA (40 wt%) blends were prepared using 1 wt% of p-toluenesulfonic acid (p-TSA) as catalyst. The proportions of CA were 0, 5, 10, and 15 wt%. The effect of the CA content on the structural, thermal, rheological, morphological, mechanical, and biodegradation properties of the blends was evaluated. Using infrared analysis (IR), a reduction of stretching vibration of OH bonds with increasing CA content was observed. The formation of an in situ compatibilizing was evidenced by IR and scanning electronic microscopy (SEM) analysis. The glass transition temperature (Tg) and the crystallinity of the TPS/PLA decreased with decreasing CA content. Rheological analysis showed a transition from elastic to viscous behavior in the TPS/PLA blends prepared with CA. The presence of CA improved the miscibility and water resistance of the TPS/PLA blends and it increased with the CA content. However, the biodegradability (18.72–25.9%) and the mechanical properties (tensile modulus: 254–423 MPa and tensile strength: 9.18–13.31 MPa) followed an opposite behavior. CA acted as crosslinking and plasticizing agent, and promoter of formation of a TPS–CA–PLA structure.
Edwin A. Murillo 한국고분자학회 2023 Macromolecular Research Vol.31 No.2
A PET nanocomposite was prepared as master batch by blending with 0.5 wt% of SiOx–PS nanoparticles via melt mixing using a twin screw extruder at 200 °C, 210 °C and 220 °C melting temperatures. The functional master batch was used to manufacture SiOx–PS (polystyrene)/PET bottle by blow molding method. The spherical SiOx–PS nanoparticle with a diameter of ~ 320 nm and surface charge value of − 22.1 mV were dispersed within the inner surface of the SiOx–PS/PET bottle. Rheological studies showed that the terminal zone slope of G′ changed along with the melting temperature, while that of the loss modulus (Gʺ) maintained the value of Gʺ ~ ω1 for all samples. The values were G′ ~ ω1.5 for pristine PET and G′ ~ ω1.4 for 200 °C/220 °C, while the nanocomposite prepared at 210 °C showed slightly increased G′ ~ ω1.6. The shear-thinning behavior was determined during frequency sweep test and showed that viscosity decreased with increase in the shear rate. The shear-thinning of pristine PET and SiOx–PS/PET was significant at lower shear rate but decreased monotonously at higher shear rate over 10 s−1. The CO2 retention of SiOx–PET bottle prepared at 210 °C showed the highest barrier property (87.1%), while pristine PET (77.6%) and other bottles provided retention of 85.7% (200 °C) and 86.0% (220 °C). Our results demonstrated that the SiOx–PS nanocomposite prepared at 210 °C induced homogeneous dispersion of nanoparticles on the inner surface of the SiOx–PS/PET bottle which improved barrier property by inhibiting the diffusion of CO2 gas molecules.