Sustainable Polyester Resins Derived from Rosins

ABSTRACTBlends of styrene-maleic anhydride (SMAH) and polyethylene-methyl acrylate-glycidyl methacrylate (E-MA-GMA) were produced in a batch mixer and in a corotating twin screw extruder. E-MA-GMA concentration was varied from 0 % to 50 %. Batch mixing indicated that the blend system was reactive. Extruded blends were characterized in terms of rheological, thermal and mechanical properties, and their morphology was observed. Rheological properties such as the storage modulus, loss modulus and complex viscosity exhibited maxima at 25 % EMA-GMA content. The blends had fine morphology as observed by scanning electron microscopy. Thermal properties were not significantly affected by the change in epoxy concentration. As E-MA-GMA concentration increased, tensile strength and modulus of elasticity decreased, but percent strain at break increased. These observations could be explained in terms of the chain extension / branching reactions that occurred in mixing the blends.

UV-LED curable coatings represent an up-to-date attractive field due to the high curing efficiency even in the presence of high filler loadings, as well as to the absence of infrared wavelengths that may negatively impact on heat-sensitive substrates. The addition of carbonaceous materials, such as biochar (BC) and/or multiwalled carbon nanotubes (MWCNTs) could positively improve both the rheological and thermal properties. In this study we report on the synthesis and characterization of carbon-reinforced films containing nanometric (MWCNTs) and micrometric (BC) carbon-based materials. We analyze the rheological properties of the UV-LED curable dispersions, as well as the thermal and optical properties of the resulting films, establishing some correlations between filler dispersion/loading with the main observed properties.

Evaluation of lubricant properties of polyolester oil blended with sesame oil-An experimental investigation

Physico-chemical, thermal and rheological properties of starches isolated from newly released rice cultivars grown in Indian temperate climates

Trimodal polymerization of polyethylene has become a research interest in recent years due to its excellent potential for altering material properties and overcoming the limitations of the bimodal process. Here, we have comprehensively investigated the effects of manipulating polymerization parameters, such as split value (SV), hydrogen‐to‐ethylene ratio (H2/C2), and stage switching, on the rheological, thermal, and mechanical properties of synthesized trimodal high‐density polyethylene (HDPE). The synthesized samples were obtained through three consecutive stages in a slurry lab‐scale reactor. The results of molten state analysis demonstrate that recipe modification, particularly SV and H2/C2 balancing in the second and third stages, had a dramatic effect on the rheological properties including dynamic moduli, G′‐G″ crossover, and the shear‐thinning behavior. Concurrently, improvements in physio‐mechanical properties, such as sagging behavior and slow crack growth resistance (SCG), were observed compared to the bimodal resin. The thermal characterization indicates that the polymerization adjustments made did not notably impact the thermal properties of HDPE samples (e.g., Tm), throughout the all‐recipe manipulation. However, minor fluctuations in crystallinity and crystallization kinetics were observed which was presumably attributed to the molecular weight of the final resin. Overall, in our trimodal polymerization recipe, the HDPE powder is within the specified range of particle size distribution, which ensures excellent bulk density and flowability.Highlights Influence of polymerization parameters such as split value, H2/C2, and stage switching in properties of trimodal HDPE. HDPE resin received from split value and H2/C2 balancing have superior SCG and sagging resistance. All HDPE samples synthesized by different recipes have similar thermal properties.

The socket plays an important role in prostheses by providing structural integrity and suspension to the distal thigh of an amputee. Heat accumulation and weight of the socket increase the energy consumption in the amputee. To overcome the same, widely used polyester-based sandwich-structured composite was reinforced with 0.2, 0.4, 0.6, 0.8, and 1 wt% multiwalled carbon nanotube (MWCNT) and analyzed for the thermal and mechanical properties. MWCNT added in a small weight proportion with polyester enhances the mechanical properties of the resulting nanocomposites as they have excellent mechanical and physical properties. The flexural and thermal property was evaluated as per ASTM D790 and ISO 22007-2 standard. It was noticed that the thermal property enhances with increase in wt% of MWCNT and mechanical properties decreased when more than 0.6 wt% MWCNT was reinforced. Hence, the sandwich-structured composite was prepared using polyester resin, 2 to 10 stockinette layers, fiberglass cloth, and 0.6 wt% of MWCNT. The thermal conductivity and flexural strength of 0.6 wt% MWCNT-reinforced sandwich-structured composite were enhanced upto 68.4% and 11.4% for 2-10 stockinette layers, respectively, while comparing to the unreinforced polyester sandwich-structured composite. The 0.6 wt% MWCNT-reinforced sandwich-structured composite may help in reducing the weight and heat build up in the socket. Hence, it is recommended to analyze further on their application in transfemoral socket preparation to bring down an amputee’s metabolic cost.

Thermal and rheological properties of plant-based natural filler-reinforced polyethylene bio-composites applying various filler loadings as well as the impacts of the different compatibilizers were investigated by means of differential scanning calorimetry and dynamic mechanical thermal analysis (DMTA). As lignocellulosic materials, such as rice-husk flour and wood flour, are eco-friendly biomaterials and a thermoplastic polymer, for example, high-density polyethylene, has good physico-mechanical and thermal properties, therefore their bio-composites can combine and utilize these two advantages at the same time. The temperature of the α-relaxation (T α) slightly increased and melting temperatures (T m) of the matrix polymer in the case of the studied bio-composites did not shift significantly as the filler loading changed, because the rigid interphase hinders the motion of polymer segments resulting in the increase in T α and only weak interactions developed at the interface between the matrix polymer and the reinforcement in the case of non-compatibilized composites. However, compatibility between the reinforcement and the matrix polymer was enhanced by incorporating compatibilizers, which further improved stiffness. From the DMTA experiment, the reinforcements result in composite samples having higher storage modulus (E′) than the neat polymer sample, indicating that incorporating lignocellulosic filler increased their stiffness.

Preparation and analysis of novel paraffin based stable nano fluid dispersed with carbon nano tubes as effective phase change material for free cooling applications

Porang (Amorphophallus muelleri Blume) contains a high amount of starch, glucomannan and Ca-oxalate. Soaking porang tuber in acid (citric acid) and salt (sodium chloride) solutions affects the Ca-oxalate content, functional, rheological and thermal properties of porang flour. The aim of this study is to thoroughly investigate the effect of soaking treatments in acid and salt solutions at different temperatures on the physicochemical, rheological and thermal properties, functional groups, molecular mass and morphology of porang flour. Soaking treatments in acid and salt solutions at different temperatures affect the properties of porang flour. This research investigated the effect of soaking porang slices in citric acid (5 %) and sodium chloride (8 %) solutions at different soaking temperatures (25, 55 and 85 °C for 1 h) on the properties of the resulting porang flour. The results of this study showed that all treatments successfully reduced the Ca-oxalate mass fraction in porang flour. The acid treatments reduced the glucomannan content more than the salt treatments. Soaking in acid solutions also decreased viscosity, molecular mass and thermal stability of porang flour. When the soaking temperature was increased, the Ca-oxalate mass fraction, molecular mass, viscosity and thermal stability of the porang flour decreased. The acid and salt treatments did not change the FTIR patterns. The morphological analysis showed that the acid and salt treatments resulted in particles with rough surface and short crystal needles of Ca-oxalate. Soaking the porang slices in salt solution at a temperature of 55 °C was the most effective treatment to reduce the Ca-oxalate content of porang flour while retaining its other quality parameters. The results of this study provided a comprehensive understanding of the effect of soaking porang slices in acid and salt solutions on the properties of the obtained porang flour. They can be used as scientific evidence on how to treat the porang slices to obtain the best quality of porang flour.

Fused deposition modeling (FDM), through 3D printing has an advantage of using thermoplastic polymers for fabrication of natural fiber reinforced composites (NFRC). Polylactic acid (PLA) is an extensively used thermoplastic in 3D printing application for its compatibility with the processing parameters. However, the uses of unfilled PLA will produce 3D printed parts with high brittleness, hence reinforcement with lignin from oil palm empty fruit bunches (OPEFB) was considered. Lignin, one of the major components in plant, was less utilized even though contains high aromatic compound that is crucial in the polymer industry. The effect of reinforcement capability of alkaline treated lignin in PLA matrix for fabrication of sustainable 3D printing material was studied where, the obtained alkaline lignin was reinforced in the PLA with various compositions (1, 3 and 5 phr). It has been found that the presence of lignin in the PLA improved the thermal properties as well as the mechanical properties of the PLA bio-composites. Nevertheless, addition of higher lignin load of more than 1 phr contributed to lower thermal and mechanical properties. Better thermal properties were found with addition of EPO, where the maximum degradation temperature and glass transition temperature of PLA bio-composite filaments (PLAE1) have been improved to 335 °C and 59 °C, respectively, instead of 330 °C and 62 °C for unfilled PLA.

Cellulose from vegetable sources is the most abundant biopolymer on earth. In plants, cellulose is a reinforcement element that conforms to a hierarchical structure. Cellulose micro-/nanofibers can be isolated from the cell wall by top-down strategies involving mechanical processes to be used in applications as a reinforcing material. Nonetheless, its use has been limited as its extraction in an aqueous medium is unfavorable when employed in low-hydrophilic matrices. Therefore, this work proposes a novel homogenization route in which cellulose micro-/nanofibers are directly obtained and dispersed in propylene glycol (PG), which generates more possibilities for these (nano) structures in applications that require water-free environments. Moreover, the influence on the cycle numbers in the morphological, chemical, thermal, and rheological properties was researched. Thus, the obtained micro-/nanofibers presented TEM diameters even below 20 nm. XRD analysis evidenced crystalline planes located at 1overline{1 }0, 110, and 200, and crystallinity degree values up to 80%. Also, FTIR spectra bands in 3340 cm−1, 2890 cm−1, 1314 cm−1, and in the fingerprint region corresponded to native cellulose Iβ. FTIR and TGA confirmed no influence of mechanical cycles on cellulose fibers’ chemical and thermal properties. Furthermore, the increase in the cycle number evidenced a shear-thinning rheological behavior of the suspensions. Considering the above results, it was concluded that the proposed high-pressure homogenization within PG is an approach for vegetable nanocellulose homogenization while maintaining high crystallinity, thermal, and chemical features with huge importance for subsequent processes in the development of nanocomposites with hydrophilic matrices for industrial applications.Graphical abstract

Preparation of polystyrene nanocomposites with functionalized carbon nanotubes by melt and solution mixing: Investigation of dispersion, melt rheology, electrical and thermal properties

Hyperbranched poly(ester)s (HBPE) possess attributes for applications in a number of areas which include platforms for controlled release of actives and as rheology modifiers and coalescent agents in coatings. For the latter applications, properties such as the glass transition temperature and thermal stability are important. A number of HBPEs were produced with varying composition, molecular weight, degree of branching and end-group functionality in order to determine the effect of each on the HBPE thermal and rheological properties. These materials were synthesized from trimethylolpropane and the difunctional acids; adipic, phthalic and terephthalic. The chemical structure of the resulting HBPEs was fully characterized, particularly by SEC and NMR, and the thermal properties by DSC and TG. The glass transition temperature was found to depend primarily on HBPE composition and end-group functionality. The prominent feature of the thermal degradation for the hydroxyl-capped HBPE was dehydrative ether formation while that for carboxyl-capped polymers was decarboxylation.

Ultra-high molecular weight polypropylene (UHMWPP), with a molecular weight of more than 106 g/mol, is expected to have superior properties, such as high mechanical strength, high thermal properties, high chemical resistance and outstanding tribological properties. However, UHMWPP has a very poor processability due to its high melt viscosity. Therefore, we aimed to improve processability of UHMWPP by blending it with a low molecular weight polypropylene (LMWPP). We attempted to improve the interfacial miscibility and intermolecular entanglement of the UHMWPP/LMWPP system by using a kneader machine. The addition of LMWPP tended to change the mechanical, thermal, and rheological properties of the blend system.

Telehelic oligodimethylsiloxanes containing 4-carboxypyrrolidone fragments were synthesized by the reactions of oligodimethylsiloxanes bearing terminal 3-aminopropyl groups with itaconic acid. The thermal and rheological properties of the obtained polymers were studied. The activation energies of viscous flow of the oligomers obtained and the previously synthesized oligodimethylsiloxanes containing terminal fragments of undecenoic or benzoic acid are compared.