Modeling of the phase behavior of polymer solutions is a crucial requirement to develop new polymer solution technologies and to design various polymer processes, such as purification, fractionation, devolatization and polymer production. In particular, the liquid-liquid equilibrium (LLE) calculation is essential for processes design of polymerization.

The hydrogen bonding in polymer solutions leads to deviate remarkably from normal solutions behaviors and is a major causes of different phase behaviors. The perturbed-chain statistical association Fluid Theory (PC-SAFT) equation of state (EoS) is applied to calculate the pressure–volume–temperature (PVT), infinite dilution weight fraction activity coefficient (WFAC), vapor-liquid equilibrium (VLE) and liquid-liquid equilibrium (LLE) of associating polymer mixtures with hydrogen bonding association such as self- and cross-association with various phase behaviors such as upper critical solution temperature (UCST), the lower critical solution temperature (LCST) and closed-loop of polymer solutions. The PC-SAFT model shows a satisfactory performance.

The aim of this work was to evaluate the utilization of analysis of the distribution of relaxation time (DRT) using a dynamic light back-scattering technique as alternative method for the determination of the concentration regimes in aqueous solutions of biopolymers (xanthan, clairana and tara gums) by an analysis of the overlap (c*) and aggregation (c**) concentrations. The diffusion coefficients were obtained over a range of concentrations for each biopolymer using two methods. The first method analysed the behaviour of the diffusion coefficient as a function of the concentration of the gum solution. This method is based on the analysis of the diffusion coefficient versus the concentration curve. Using the slope of the curves, it was possible to determine the c* and c** for xanthan and tara gum. However, it was not possible to determine the concentration regimes for clairana using this method. The second method was based on an analysis of the DRTs, which showed different numbers of relaxation modes. It was observed that the concentrations at which the number of modes changed corresponded to the c* and c**. Thus, the DRT technique provided an alternative method for the determination of the critical concentrations of biopolymers.

Cellulose nanocrystals (CNCs) with similar size and various surface charge densities were prepared by sulfuric acid hydrolysis and NaOH desulfation. The influence of surface charge density and NaCl concentration on the intrinsic viscosity of CNC suspensions and predicted aspect ratio were investigated by Ubbelohde viscometer. With decreased CNC surface charge density, the intrinsic viscosity initially decreased due to the electric double layers on the CNC surface and subsequently increased due to CNC aggregation. To screen electroviscous effect, NaCl was added into CNC suspensions. With increased NaCl concentration, the intrinsic viscosity of CNC suspensions first decreased and then increased. The aspect ratios of CNCs predicted by Batchelor equation from the minimum intrinsic viscosity were consistent with that measured by transmission electron microscopy (TEM). Suspensions of CNCs with higher surface charge density needed less NaCl to obtain minimum intrinsic viscosity. The NaCl content that should be added to the suspension to predict the actual physical aspect ratio of CNC can be estimated by Debye-Hückel theory, assuming that the Debye length is equal to the CNC diameter..

Cationic porphyrins interact with DNAs. Binding mode of porphyrins depends on various factors including nature of DNA sequences and the periphery substituents. Trans-bis(N-methylpyridium-4-yl) diphenyl porphyrin (trans-BMPyP) also bind to DNAs. Upon binding to poly[d(A-T)₂], typical circular dichroism (CD) spectrum in the DNA absorption region for B-form was reversed, suggesting formation of left-handed helical structure (Z-form). The formation of Z-form was confirmed by ³¹P NMR, in which a single ³¹P peak of B-form was split into two peaks, reflecting two distinctive environment for the DNA phosphate groups, which is typical for Z-form DNA. Trans-BMPyP-induce B-Z transition occurred specifically for polynucleotide having alternated AT sequences. No other combination of nucleobase sequence produced similar B-Z transition. This observation is in contrast with typical DNA sequence, alternating GC sequence (poly[d(G-C)₂]),  that exhibits the B-Z transition. Cationic porphyrin has been known to intercalate between GC base pairs, while they stack along AT-rich DNAs. Pattern of stacking along DNA stem may be an important factor for this alternating AT sequence-specific B-Z transition. B-Z transition of alternating AT sequence requires at least 14 base-pairs, supporting the importance of porphyrin stacking along AT stem. The position of cationic ion on the periphery methyl pyridine ion also takes an essential role. When the methyl group locates at meta- or para-position, both cationic porphyrins similarly induce B-Z transition, while that at ortho-position, in which free-rotation of pyridine ring is sterically prevented, did not. This observation also indicated the importance of stacking of porphyrins along poly[d(A-T)₂] stem, because the former two porphyrins can be planar, therefore can stack each other. On the other hand, ortho-trans-BMPyP cannot be planar and stacking is inefficient. 

Statement of the Problem: Vegetable oils and lignocellulosic biomass are two major types of bio-based resources gaining interest for bio-based polyols for polyurethane (PU) production. However, the consumption of huge amounts of vegetable oils could result in a shortage of vegetable oils and will cause the increase in food prices. Therefore, lignocellulosic biomass is seen as a better alternative raw material for PU production. Various kinds of lignocellulosic biomass, have been used for the production of bio-based PU foams but the use of lignocellulosic rice straw is not yet explored. Thus, the study aims to develop a PU rigid foam from rice straw-based polyol and investigate the effect of isocyanate index on the thermophysical properties of the foam. Methodology & Theoretical Orientation: PU foams were prepared by reacting isocyanates in varying indices with polyols containing 15% of rice straw-based polyol and 85% petroleum-based polyol and their thermal conductivity, density and compressive strength were determined.  Findings: PU foams with no biopolyol replacement has superior thermal and mechanical properties over the PU foams with biopolyol replacement. However, those with biopolyol replacement were significant less dense compared to the commercial formulation. This could indicate possible application in industries where lightweight materials is important. Thermal characterization of the foam samples at different isocyanate indices indicate that increasing the isocyanate content improves insulation property of the PU as evident with the decreasing conductivity. This is also true with compressive strength. The index is directly proportional to the compressive strength. Density, on the other hand, is directly proportional to the isocyanate content. Conclusion & Significance: Successful development of PU rigid foam products using biomass-based polyols obtained from a renewable feed stock rice straw offers a practical and economic procedure for potential scale-up and commercialization. 

Statement of the Problem: Polyurethane is a versatile class of polymer produced from the condensation polymerization of isocyanates and polyol, a hydroxyl-rich compound. Its application can be found in adhesives, sealants, coatings, flexible and rigid foams. However, polyol is traditionally sourced from petroleum raw materials. With increasing environmental and sustainability problems, lignocellulosic biomass is a potential alternative source due to its abundance, biodegradability and its hydroxyl component. In the Philippines, 11.3 M tons of rice straw is produced annually which when burned, produces air pollutants such as carbon dioxide, nitrogen oxide and sulfur dioxide. Rice straw can be liquefied using an atmospheric liquefaction process with the use of a catalyst. Researchers reported that varying liquefaction parameters can significantly alter the properties of a polyol³. The purpose of the study is to produce rice straw-based polyol with a low acid number, high OH number, low viscosity and high liquefaction ratio which is suitable for rigid foam applications. Methodology & Theoretical Orientation: A one-pot liquefaction process was used to liquefy rice straw with the use of sulfuric acid as catalyst and crude glycerol as liquefaction solvent. Response surface methodology was used to optimize four factors: acid loading, biomass loading, reaction time and reaction temperature based on four responses: acid number, OH number, liquefaction ratio, and viscosity.  Findings: Statistical analysis showed that all four factors have a significant effect on polyol properties. Increasing the acid loading was shown to significantly increase residual acid while higher reaction times lead to a decrease in liquefaction efficiency. Polyols with optimum properties were produced at a reaction time of 180-300 minutes, acid loading of 1-2%, reaction temperature of 170-180°C, and a biomass loading of 10-15%.

In this article, antibacterial film based on low density polyethylene (LDPE), potassium sorbate (KS) and ethylene vinyl alcohol (EVOH) copolymer were prepared and characterized using scanning electron microscopy(SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), differential scanning calorimetry (DSC), and tensile tests. The oxygen barrier properties of the LDPE/EVOH/KS film were significantly better than those of the LDPE/KS film. In addition to barrier properties, the LDPE/EVOH/KS film also had better elastic modulus than their counterparts without EVOH. The antimicrobial film containing potassium sorbate decreased the growth rate and maximum growth of yeast, and extended the lag period before mold growth was apparent. Therefore, it can prevent or reduce the rate of microbial spoilage in low viscosity liquids and on the contacted surface area of solid food products and as the result may prolong the shelf life of food products when it is used as a packaging material. Also, a novel sticker sensor has been fabricated based on methyl red, and tests have been conducted to detect the freshness of meat by its color change in real time (when the red methyl red paper changed to yellow). These are prepared by entrapping within a pH sensitive dye that responds, through visible color changes to the spoilage volatile compounds that contribute to a quantity known as total volatile basic nitrogen (TVBN). Finally, the methyl red was successfully used as a sticker sensor for the real-time monitoring of meat freshness in ambient and chiller conditions.

In this article, nanocomposite films based on low density polyethylene (LDPE), organoclay (OC) and ethylene vinyl alcohol (EVOH) copolymer were prepared and characterized through using scanning electron microscopy(SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), differential scanning calorimetry (DSC), oxygen permeation measurements, and tensile tests. The oxygen barrier properties of the LDPE/EVOH/OC film were better than those of the LDPE/OC film. In addition to barrier properties. Furthermore, from the TEM micrographs, the O2 permeability through the films was evaluated, which illustrated that adding both OC and LDPE to EVOH leads to a remarkable increase in the barrier properties of EVOH films. Also, a new colorimetric indicator sensor based on methyl red was sensitive to total volatile basic nitrogen (TVBN) released from red meat during storage which has been fabricated for real-time monitoring of meat quality. The methyl red as a freshness sensor worked based on pH increase as the basic spoilage volatile amines produced gradually in the package headspace, and subsequently, the colour of the sensor will change for spoilage indication, which is easily visible to the naked eye. The results reveal that the sticker sensor could be used to determine the degree of red meat cut freshness, as the relationship between the colour change of methyl red as a sensor response and the meat freshness follows a similar trend. Results have indicated that sensor response correlated well with microbial load of red meat, thus enabling the sensor for real-time monitoring of red meat spoils.