Synthesis and characterization of unsaturated polyester/carborundum composites

Two unsaturated polyesters, one based on phthalic anhydride PE_P and the other based on isophthalic acid PE_I, were synthesized. The chemical structure of the two polyesters was characterized by IR and ¹H and ¹³C NMR spectroscopy. The effect of styrene concentration on the curing of polyesters was also studied. It has been found that the percent of polyester/styrene (70/30 wt %) gave the highest percent of curing. Different concentrations of carborundum (0–70 wt %) were used to prepare polyester composites. A comparative study was done on the properties of the two prepared polyesters PE_P and PE_I and their composites in term of their thermal, mechanical, electrical, and physical properties. The results indicate that the polyester based on isophthalic acid (PE_I) and its composites gave higher compressive strength values and lower water absorption than those based on phthalic anhydride (PE_P). The presence of carborundum improved the thermal stability than the cured polyesters and electrical properties. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Synthesis and characterization of brominated polyester composites

Two unsaturated polyesters containing a halogen (bromine) in the backbone of the polymer chain were synthesized and compared with a halogen‐free polyester. The bromine content was measured by elemental analysis. The chemical structures of the polyesters were characterized by means of IR and ¹H‐NMR spectroscopies. Feldspar was used as the filler to form the polyester composites. The effects of the halogen substituents, filler concentration, and crosslinking monomers and comonomers on the electrical and mechanical properties of the polyester composites were studied. The flammability was also investigated. The styrenated polyesters and their composites achieved fire resistance and good mechanical and electrical properties. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1356–1365, 2006     

Dielectric and mechanical properties of natural nanofibers‐reinforced ethylene propylene diene rubber: Carrot foliage and corn gluten

A study has been carried out to investigate the dielectric and mechanical properties of composites based on reinforcing carrot foliage (CF) and corn gluten meal (CGM) as by‐products of food processing units into ethylene propylene diene rubber matrix. Transmission electron microscope micrographs indicate that both types of fillers are in the nanoscale. The permittivity ε′ and dielectric loss ε″ were measured in the frequency domain and at room temperature ～ 25°C. The increase in ε′ and ε″ by increasing filler content is due to its reinforcing nature which was found to be more pronounced in case of CF than CGM. The mechanical properties are found to increase in the same manner. The values obtained for ε′ and ε″recommend such composites to be used in the electrical insulation purposes. The analysis of composite morphology indicated that at low concentration both types of fillers are fine distributed in the EPDM matrix, whereas at higher filler loading aggregation of filler is clearly appeared. The composites under investigation are found to be highly thermal aging resistant as both electrical and mechanical properties are slightly affected by such aging. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers     

Electrical and thermal studies of the distribution of carbon black in a polyester matrix in the presence of aluminum oxide

The distribution of a filler in a polymeric matrix is one of the most important factors affecting the physical properties of the final product. For this reason, the main objective of this study was to introduce aluminum oxide (Al₂O₃), acting as a dispersing agent, to reduce the filler–filler interaction and enhance the filler–polymer interaction. To achieve this aim, the electrical behavior of a styrenated polyester resin filled with different amounts of high‐abrasion furnace black in the presence of 5% Al₂O₃ was studied in the vicinity of the percolation threshold to evaluate the effect of the addition of Al₂O₃ in an attempt to reduce the filler–filler interaction through the polyester matrix. At a certain concentration of carbon black, an abrupt increase was noticed through electrical conductivity, permittivity, and dielectric loss investigations. With this increase, the tendency of conductive chain formation increased through the aggregation of a carbon black particle network. The addition of 5% Al₂O₃ improved the filler distribution by lowering the aggregate size and consequently enhanced the formation of the network. From the Arrhenius temperature dependence of the electrical conductivity, the activation energy and pre‐exponential factor were obtained, and they confirmed the validity of the compensation law for the semiconducting composite systems. The composites were also analyzed by thermogravimetric analysis. Al₂O₃ improved the thermal stability of the composites in comparison with that of a sample free of Al₂O₃. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Poly(ethylene isophthalate)s: effect of the tert-butyl substituent on structure and properties

A comparative study of the two isophthalic acid deriving homopolyesters poly(ethylene isophthalate) (PEI) and poly(ethylene 5-tert-butyl isophthalate) (PE^tBI), including synthesis, crystal structure, and thermal and permeability properties, was carried out. The two polyesters were prepared by condensation polymerization in the melt. In both cases, minor amounts of cyclic dimers were observed to form, which were characterized by nuclear magnetic resonance and mass spectroscopy. PEI and PE^tBI were thermally stable up to 400 °C and they appeared to be semicrystalline polyesters, having their melting temperatures between 130 and 135 °C. Their glass-transition temperatures were 62 and 94 °C, respectively. The crystal structure adopted by the two polyesters seemed to consist of a regularly folded conformation, clearly different from the almost extended conformation characteristic of poly(ethylene terephthalate). Gas permeability measurements for N₂, O₂, and CO₂ revealed that PE^tBI is more permeable to these gases than PEI, in spite of having a higher T_g. Furthermore, water vapor diffusion was found to be increased by the insertion of the tert-butyl group, whereas water absorption diminished. The differences in gas and water vapor transport properties observed for these two polyesters were discussed on the basis of their respective molecular structures.     

Comparison of the mechanical properties and interfacial interactions between talc,kaolin, and calcium carbonate filled polypropylene composites

Three types of mineral fillers—talc, calcium carbonate (CaCO₃), and kaolin (10–40 wt % filler loadings)—were compounded with polypropylene (PP) with a twin‐screw extruder. The composites were injection‐molded, and the effects of the filler loading on the mechanical, flow, and thermal properties for the three different types of filled composites were investigated. The aim was to compare their properties and to deduce prospective filler combinations that would yield hybrid PP composites in following studies. The results showed that in most cases, the strength and stiffness of the talc‐filled PP composites was significantly higher than those of the CaCO₃‐ and kaolin‐filled PP composites. However, CaCO₃, being a nonreactive filler, increased the toughness of PP. The kaolin‐filled PP composites also showed some improvement in terms of strength and stiffness, although the increases in these properties were not as significant as those of the talc‐filled PP composites. The effects of interfacial interactions between the fillers and PP on the mechanical properties were also evaluated with semiempirical equations. The nucleating ability of all three fillers was studied with differential scanning calorimetry, and the strongest nucleating agent of the three was talc, followed by CaCO₃ and kaolin. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3315–3326, 2004     

Synthesis of flame retardant polyester‐urethanes and their applications in nanoclay composites and coatings

This paper describes the synthesis of phosphorus‐containing polyester‐urethanes and their applications in nanoclay composites and coatings. Polyester was prepared by the reaction of bis(bisphenol‐A) monophenyl phosphonate, maleic anhydride and phthalic anhydride. The polyester was reacted with various diols such as ethylene glycol, diethylene glycol and propylene glycol to obtain polyester polyols. Synthesized polyester polyols were characterized by chemical analysis and instrumental analysis and was used further to react with different isocyanates to develop polyester‐urethanes. The synthesized polyester‐urethanes were blended with organo‐modified montmorillonite nanoclay (1 wt%, 3 wt% and 5 wt%) and were cast in a mold and coated on mild steel panels. The thermal stability of neat polyester‐urethane and the nanoclay composites was determined by thermogravimetric analysis. The flame retardant properties of cast films and their composites were determined by the limiting oxygen index and UL‐94 test methods. The physical and mechanical properties of coatings such as pot life, drying properties, scratch hardness, pencil hardness, impact resistance, adhesion and flexibility were investigated. The chemical resistance properties of the coatings were also determined in different reagents. The data reveal that the polyester‐urethane nanoclay composites with 3 wt% clay hold promise for use in effective flame retardant coatings. © 2013 Society of Chemical Industry     

Electrical,rheological, and mechanical properties copolymer/carbon black composites

This work aims to evaluate the electrical conductivity and the rheological and mechanical properties of copolymer/carbon black (CB) conductive polymer composites (CPCs). The copolymers, containing ethylene groups in their structure, used as matrix were polyethylene grafted with maleic anhydride (PEgMA), ethylene-methyl acrylate–glycidyl methacrylate (EMA-GMA), and ethylene-vinyl acetate (EVA). For comparison purposes, bio-based polyethylene (BioPE)/CB composites were also studied. The electrical conductivity results showed that the electrical percolation threshold of BioPE/CB composite was 0.36 volume fraction of CB, whereas the rheological percolation threshold was 0.25 volume fraction of CB. The most conductive CPC was BioPE/CB. Among the copolymer/CB CPCs, PEgMA/CB showed the highest conductivity, which can be attributed to the fact that the PEgMA copolymer had higher crystallinity. It also has a higher amount of ethylene groups in its structure. Torque rheometry analysis indicated that EMA-GMA copolymer may have reacted with CB. Rheological measurements under oscillatory shear flow indicated the formation of a percolated network in BioPE/CB and copolymer/CB composites. Morphology analysis by scanning electron microscopy (SEM) indicated the formation of a percolated network structure in BioPE/CB composite and finely dispersed CB particles within the PEgMA copolymer. Wetting of CB particles/agglomerates by the copolymer matrix was observed in EVA/CB and EMA-GMA/CB composites. Conductive CB acted as reinforcing filler as it increased the elastic modulus and tensile strength of BioPE and the copolymers.     

Study on effect of filler loading on the flow and swelling behaviors of polypropylene‐kaolin composites using single‐screw extruder

Melt flow and extrudate swelling behavior of polypropylene‐kaolin (PP‐Kaolin) composites were investigated using a single‐screw extruder. Kaolin was mixed with polypropylene (PP) using a heated two‐roll mill at 185°C and the filler loading were varied from 5 to 30 wt %. Subsequently, flow behavior of the compounded formulations were evaluated through Melt Flow Index (MFI) measurement at various temperatures ranging from 190 to 230°C. The extrudate swelling ratio was also measured by using an image analysis instrument and software. It was proven that the MFI decreased with increasing loading of kaolin for test temperatures of 190 and 200°C. However, for temperatures exceeding 200°C, the MFI value rose slightly at 5 wt % of kaolin content then seemed to reduce as more kaolin was added. This is also detected in rheological measurement where the apparent visosity, η_app, appear to be lowered at 5 wt % loading of kaolin. Further increase in kaolin loading resulted in increasing value of the composites η_app. The swelling ratio decrease with increasing filler loading for composites below 20 wt %. However, at 30 wt % of kaolin content, the extrudate swelling ratio increased and noticeable blistered surface texture was observed on the extrudate surface. Furthermore, at this level of filler loading, shrinkage occurence due to the existence thermal gradient between the surface and the inner core of the extrudate caused void formation in the middle section of the extrudate. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Ionic polymers with tunable liquid‐crystalline properties

Side‐chain polyesters were synthesized from N‐octyl‐, N‐dodecyl‐ or N‐hexadecyl‐diethanolamine and succinic acid anhydride. These polyesters were then transformed into polyester hydrochlorides by protonation of the amino groups using different amounts of HCl (20–100 mol%). Above 60 mol% the reaction is not quantitative and a degree of protonation of up to 88% is obtained. The structures of the synthesized polyesters and their hydrochlorides were determined by ¹H nuclear magnetic resonance spectroscopy. The thermal properties of the synthesized polyesters and their hydrochlorides were also studied using differential scanning calorimetry in relation to the side‐chain length and the degree of polyester protonation. The polyester with octyl side chains and its hydrochlorides were amorphous liquids at room temperature, while the polyester and polyester hydrochlorides with hexadecyl side chains formed a smectic crystalline phase, S_mB, or its tilted analogues. The polyester with a dodecyl side chain was also an amorphous liquid at room temperature, while its hydrochlorides with various degrees of protonation were smectic liquid crystals, as determined by X‐ray diffraction. By simply varying the degree of protonation the liquid crystal isotropization temperature was increased from 32 °C to 82 °C. Copyright © 2011 Society of Chemical Industry     

Physico‐mechanical,thermal, and coating properties of composite materials prepared with epoxy resin/steel slag

The interest in using different solid waste as reinforcement in polymer composite preparation has increased considerably in recent years. Slag is one of the inorganic waste materials obtained from ore processing. In this work, epoxy composites filled with different percentages of slag were prepared. Physico‐mechanical, thermal, and coating properties of these composites were determined depending on the amount of filler, type of hardener, and polyethylene glycol (PEG) addition. X‐ray diffraction (XRD) studies were carried out to examine the compatibility of the filler and epoxy resin and XRD results showed good compatibility between two materials. The results of mechanical testing illustrated that hardness of the epoxy composites containing anhydride was partially higher than with Epamine PC17 in contrast to elongation at break. The tensile strength and Young modulus decreased with increasing filler amount. When compared to neat epoxy resin, corrosion, and adhesion properties of the composites with filler addition did not change significantly. The highest water sorption values were obtained for the epoxy composites with PEG addition. The composites hardened by anhydride had better thermal stability than the composites including Epamine PC17. POLYM. COMPOS., 38:1974–1981, 2017. © 2015 Society of Plastics Engineers     

Effect of chemical treatments on the mechanical,flow, and morphological properties of talc‐ and kaolin‐filled polypropylene hybrid composites

This study was performed with commercially available phenyl trimethoxysilane (PTMS) and neoalkoxytitanate [i.e., neopentyl(diallyl)oxytri(dioctyl)phosphato titanate (LICA 12)] as coupling agents. PTMS and LICA 12 were used to treat talc and kaolin to compare their effects with untreated fillers upon incorporation into polypropylene (PP). Single‐filler PP composites (containing either talc or kaolin) and hybrid‐filler composites (containing a mix of both talc and kaolin) were compounded in a twin‐screw extruder and subsequently injection‐molded into dumbbells. The incorporation of PTMS and LICA 12 slightly decreased the tensile and flexural properties in terms of modulus and strength but increased the elongation at break for both single‐filler and hybrid‐filler composites. There was also a significant improvement in the impact strength of the composites, particularly those treated with LICA 12. The hybrid composites, through the synergistic coalescence of positive characteristics from talc and kaolin with the aid from chemical treatment provided an economically advantageous material with mechanical properties comparable to those of the single‐filler‐filled PP composites. Further investigations on flow and morphological properties were also done to correlate the mechanical properties of the single‐ and hybrid‐filler‐filled PP composites. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis and characterization of fumarate-based polyesters for use in bioresorbable bone cement composites

Fumarate-based polyesters were prepared by the transesterification polycondensation of diethyl fumarate and diols: (±)-1,2-propanediol, (S)-(+)-1,2-propanediol, 2-methyl-1,3-propanediol, and 2,2-dimethyl-1,3-propanediol. Different polyester microstructures were observed by ¹H-NMR and ¹³C-NMR spectroscopy when the reaction was conducted in the presence of p-toluenesulfonic acid monohydrate or metal containing catalysts—aluminum trichloride, titanium tetrachloride, titanium tetrabutoxide, and zinc chloride. The extent of formation of branched structures associated with hydroxyl end groups' addition to the unsaturated polyester double bonds depends on the acidity of the catalyst. The bone cement composites were prepared by mixing the fumarate polyesters with an inorganic filler, CaSO₄ · 2H₂O, and N-vinyl pyrrolidone, which crosslinks on the addition of a radical initiator, benzoyl peroxide, at ambient temperatures. The compressive strength and hydrolytic stability of the cement compositions was correlated with structure of the polyesters. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 1123–1137, 1997     

The effect of alkali treatment and filler size on the properties of sawdust/UPR composites based on recycled PET wastes

In this study, natural sawdust fillers from acacia were mixed with unsaturated polyester resin (UPR), which was prepared by recycling of polyethylene terephthalate (PET) waste bottles to prepare sawdust/UPR composite. PET wastes were recycled through glycolysis and depolymerized to produce a formulation for the resin. The effects of alkali treatment, filler content, and filler size on the tensile, flexural, hardness, and water absorption of the composites were investigated. The results show that the modulus of both tensile and flexural increased with increasing filler contents, but the tensile and flexural strength of composites decreased. The size of sawdust also played a significant role in the mechanical properties, with smaller size sawdust producing higher strength and modulus. This is due to the greater surface area for filler–matrix interaction. The results also show that alkali treatment causes a better adhesion between sawdust and UPR matrix and improves the mechanical properties of the composites. Furthermore, surface treatment reduced the water absorption of composites. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Preparation and characterization of some new unsaturated polyesters based on 3,6‐bis(methoxymethyl)durene

A series of unsaturated polyester resins based on 3,6‐bis(methoxymethyl)durene with different diacids or anhydrides, namely, phthalic anhydride, maleic anhydride, and succinic acid, and different glycols, namely, 1,2‐propylene glycol, triethylene glycol, 1,4‐cyclohexane diol, and 3,6‐bis(benzyloxymethyl)durene, were prepared. Infrared and nuclear magnetic resonance spectra were used to characterize the unsaturated polyester resins obtained qualitatively and quantitatively. The average‐number molecular weight (M^?_n) was determined by end‐group analysis. These polyesters were found to cure with styrene at room temperature. The thermal behavior of the styrenated polyesters was studied via thermogravimetrical analysis and differential scanning calorimetry (TGA and DSC). © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 3388–3398, 2001     

Evaluation of surface-active agents by mechanical properties of highly filled composites

Mechanical spectroscopy is used to study the behavior under accelerated aging of surface-active additives in highly filled composites using a binder based on an hydroxyl-terminated polybutadiene. First, the mechanical properties of composites containing an amine polyester or an aziridine polyester are compared to those of a composite without any surface-active agents. It is thus confirmed that the aziridine polyester is a better surface-active agent than the amine polyester. The improvement in properties from the aziridine polyester is not affected by accelerated aging at 333°K. It was also established that composites with a mixture of both polyesters showed adequate initial mechanical properties and maintained those properties upon accelerated aging. Various hypotheses are proposed to explain the behavior of surface-active agents.     

Thermal,electrical, and mechanical properties of Si3N4 filled LLDPE composite

Silicon nitride (Si₃N₄) filled linear low-density polyethylene (LLDPE) composite was prepared. The effects of Si₃N₄ filler content, dispersion, and LLDPE particle size on the thermal conductivity, and Si₃N₄ filled content on the mechanical and electrical properties of Si₃N₄ reinforced LLDPE composites prepared using powder mixing were investigated. The results indicate that there existed a unique dispersion state of Si₃N₄ particles in LLDPE, shell-kernel structure, in which Si₃N₄ particles surrounded LLDPE matrix particles. With increasing filler content and LLDPE particles size, thermal conductivity increased, and reached 1.42 W/m K at 30 vol% of filler, seven times as that of unfilled LLDPE. Furthermore, the examinations of Agari model demonstrate that larger size LLDPE particles form thermal conductive networks easily compared with smaller ones. The values predicted by theoretical model underestimate the thermal conductivity of Si₃N₄/LLDPE composites. In addition, the composites still possessed rather higher electrical resistivity and dielectric properties, but the mechanical properties decreased. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

Dielectric and morphological studies on polyester/nanosilica fume composites

Styrenated polyester nanocomposites are a class of polymers reinforced with low quantities of well‐dispersed nanoparticles with the aim of offering advantages over conventional composites. Nanosilica fumes with different particle sizes were used as a filler to form polyester nanocomposites. The average particle size was detected with transmission electron microscopy. We used the electrical properties [permittivity (?′), dielectric loss (?″), and electrical conductivity (σ)] to investigate the variation of the properties of the polyester/nanosilica fume composites by varying the filler ratio and particle size as well. The ?′, ?″, and σ values were found to increase with increasing filler content up to a certain concentration, at which aggregation began to form and after which stability in these properties was attained. The second relaxation time (τ₂) associated with the orientation of the aggregates caused by the movement of the main chain was found to be unchanged up to a certain concentration of filler, after which a pronouncing increase in τ₂ was noticed. This result found further justification through the scanning electron micrographs. In addition, the values of σ, which were of the order of 10^?11 S/cm, make the materials highly recommended for use for insulation purposes. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis and properties of multiarm star hydroxyl-terminated polyesters for two-component polyurethane coatings

A series of multiarm star hydroxyl-terminated polyesters (MHPs) were synthesized through a “one-pot” method with di-trimethylolpropane as the core molecule, 2,2-dimethylolpropionic acid as the AB₂-type monomer, ε-caprolactone, and monocarboxylic acids as modifiers. The influence of different monocarboxylic acids on the viscosities of polyesters and their 2K-PU films hardness was studied and it was found that MHPs prepared from lauric acid displayed the higher films hardness and lower viscosities. IR spectra of MHPs disclosed the ring-opening reaction between ε-caprolactone and hydroxyl groups occurred. ¹H NMR spectra demonstrated that the molecular structures of MHPs were irregular due to the multiplicity of reaction processes. The measured number-average molecular weights (M _n) of MHPs were around 715–1854 g/mol with the PDI of 1.45–2.05. MHPs exhibited lower viscosities in the range of 3304–9060 mPa s at 100% solid contents and possessed lower intrinsic viscosities compared with linear polymers of similar molecular weight. The cured films of MHPs exhibited excellent impact resistance, adhesion, flexibility, and high hardness and displayed good thermal stability with 5% weight loss at 280°C. The solution viscosities of MHPs were less than 450 mPa s at 80% solid contents, and the VOC contents of 2K-PU coatings obtained from MHPs were low to 300 g/L.     

Synthesis and characterization of novel water‐soluble polyesters for electrical insulation

Polyesters based on poly(alkyl anhydride), aromatic anhydrides, and polyglycols were synthesized by thermal and catalytic condensation polymerization techniques. The polymerization conditions were optimized by the variation of the monomer concentration, reaction temperature, and so on to achieve the desired properties. The reaction was monitored by the measurement of the acid values at different stages of the polymerization reaction. The water solubility of these polyesters was achieved by the termination of the reaction with the addition of ammonia. These polyester resins were characterized with IR and viscosity measurements. The electrical properties of polyester resins coated and cured on glass cloth were measured with the idea of using them as impregnating varnishes. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007