Semiaromatic Poly Research Articles

Semiaromatic Poly(ester imide) Copolymers with Alicyclic Diamines for Low-K Properties at a High Frequency of 10–40 GHz

Semiaromatic Poly(ester imide) Copolymers with Alicyclic Diamines for Low-K Properties at a High Frequency of 10–40 GHz

Synthesis of Highly Transparent Semi-aromatic Poly(amide–imide)s from Alicyclic Diamines and Dicarboxylic Acids Derived from 2,2'-Di(trifluoromethyl)benzidine with Trimellitic Anhydride

Synthesis of Highly Transparent Semi-aromatic Poly(amide–imide)s from Alicyclic Diamines and Dicarboxylic Acids Derived from 2,2'-Di(trifluoromethyl)benzidine with Trimellitic Anhydride

Interfacial Enhancement and Composite Manufacturing of Continuous Carbon-Fiber-Reinforced PA6T Composites via PrePA6T Ultrafine Powder.

Semi-aromatic poly (hexamethylene terephthalamide) (PA6T) oligomer (prePA6T) ultrafine powder, with a diameter of <5 μm, was prepared as an emulsion sizing agent to improve the impregnation performance of CF/PA6T composites. The prePA6T hyperfine powder was acquired via the dissolution and precipitation "phase conversion" method, and the prePA6T emulsion sizing agent was acquired to continuously coat the CF bundle. The sized CF unidirectional tape was knitted into a fabric using the plain weave method, while the CF/PA6T laminated composites were obtained by laminating the plain weave fabrics with PA6T films. The interfacial shear strength (IFSS), tensile strength (TS), and interlaminar shear strength (ILSS) of prePA6T-modified CF/PA6T composites improved by 54.9%, 125.3%, and 120.9%, respectively. Compared with the commercial polyamide sizing agent product PA845H, the prePA6T sizing agent showed better interfacial properties at elevated temperatures, especially no TS loss at 75 °C. The SEM observations also indicated that the prePA6T emulsion has an excellent impregnation effect on CF, and the fracture mechanism shifted from adhesive failure mode to cohesive failure mode. In summary, a facile, heat-resistant, undamaged-to-fiber environmental coating process is proposed to continuously manufacture high-performance thermoplastic composites, which is quite promising in mass production.

Surface Modification of Nanofiltration Membranes by Interpenetrating Polymer Networks and Their Evaluation in Water Desalination

Membrane separation is the most widely used technology in desalination to produce drinking water that requires improved permeability and salt rejection. The objective of the present study is to modify fully aromatic polyamide (NF90) and semiaromatic poly(piperazine-amide) (NF270) nanofiltration membranes via interpenetrating polymer networks of [3-(acryloylamino)propyl]trimethylammonium chloride (ClAPTA), 2-acrylamide-2-methyl-1-propanesulfonic acid (APSA), and glycidyl methacrylate–N-methyl-d-glucamine (GMA-NMG). The surface topography of the modified NF270 and NF90 membranes was analyzed by SEM and AFM. The modified NF270 membrane showed more significant roughness changes than the original (39%), while the modified NF90 membrane showed slight changes (7%). The FTIR results showed the chemical modifications introduced in the membranes. The best modified NF90 membrane (0.13 M GMA-NMG-0.07 M APSA) showed an 84.3% and 0.6% increase in water flux and chloride rejection for filtration of a model solution, respectively, compared to the commercial membrane. Furthermore, the best membrane modification was achieved with P(ClAPTA-co-GMA-NMG), increasing seawater permeability by 300% without modifying the high rejections of the original membranes. This work provides a guide to improving the permeability of NF membranes without sacrificing a higher species rejection by modification with interpenetrating polymers.

Heat-resistant colorless polyimides from benzimidazole diamines: Synthesis and properties

To prepare colorless polyimides (CPIs), two novel diamines, namely 6-amino-2-(2′-methyl-4′-aminobenzene)-N-phenylbenzimidazol (5a) and 6-amino-2-(2′-trifluoromethyl-4′-aminobenzene)-N-phenylbenzimidazol (5b) were synthesized, and two series of polyimides derived from them were developed. Except for the inherent asymmetric structures, the twisted moieties had been successfully incorporated in the benzimidazole dianmines through 2′- and N-substituents. The loose chain packing and hindered charge transfer (CT) interaction caused by the askew and distorted segments provided the polyimides with excellent optical transparency (80% transmittance at 400 nm, semi-alicyclic series), while the resulting films inherited the unique superheat-resistance of poly(benzimidazole imide)s (PBIIs), e.g., high glass-transition temperatures (up to 402 °C). Such outstanding optical and thermal properties expanded their application as heat-resistant colorless materials. Furthermore, the correlation between various 2′-substituents and characters of these PBII films was systematically analyzed. These data indicated that these colorless polyimides had potential application as optical and optoelectronic materials. • Two novel benzimidazole dianmines containing 2′- and N-substituents (5a and 5b) were successfully synthesized. • Polyimide films with asymmetric and twisted structures were successfully synthesized. • The semi-aromatic poly(benzimidazole imide) films achieved colorlessness (T 400 = 80–81% and T g = 394–402 °C). • The effect of various 2′-substitutions on the properties of these N-phenyl-poly(benzimidazole imide)s was investigated.

One-pot synthesis of hydroxyl terminated hyperbranched semi-aromatic Poly(ester-imide)s

A new kind of hyperbranched semi-aromatic poly(ester-imide)s with hydroxyl terminated groups has been prepared from commercially available 1,2,4-benzenetricarboxylic anhydride (TMA) as the AA′-type aromatic monomer and 3-amino-1,2-propanediol (3APPD), 2-amino-1,3-propanediol (2APPD), N,N-bis(2-hydroxyethyl)ethylenediamine (BHED) as CB 2 -type aliphatic monomers via a simple one-pot melting polymerization method. The effects of synthesis conditions on the structures and properties of the products were investigated in detail. The combination of FTIR, 1 H NMR, 2D NMR, MALDI-FTICR-MS and model reactions have been used to characterize the structures of the obtained polymers. As assessed using thermal measurements, the obtained hyperbranched semi-aromatic poly(ester-imide)s possess low glass transition temperature (≤120 °C) and high thermostability with an onset decomposition temperature ranging from 355 to 420 °C in nitrogen. The products possess abundant terminal hydroxyl functional groups. Hydroxyl values vary between 198 and 248 mg KOH/g depending on the particular precursors used to generate the polymers. The synthesis of hydroxyl terminated hyperbranched semi-aromatic poly(ester-imide)s. • Hyperbranched semi-aromatic poly(ester-imide)s were prepared by one-pot melting polymerization. • HBPEIs possess low T g and high thermostability. • HBPEIs are terminated by abundant hydroxyl function groups. • This synthetic strategy exhibits good fault-tolerant ability for reaction condition.

Improved interfacial shear strength in carbon fiber enhanced semi-aromatic polyamide 6T composite via in-situ polymerization on fiber surface

The interfacial property of carbon fiber (CF) reinforced semi-aromatic poly (hexamethylene terephthalamide) (PA6T) thermoplastic composite has been improved by in-situ polymerization on fiber surface. On that basis, PA6T oligomer was coated upon fiber to form a reactive polymeric layer and modified fiber surface structure. SEM, FTIR and XPS analysis were conducted to investigate its surface status, finding that CF was perfectly wetted and formed a much rougher surface on which large quantity of polar –CO–NH- groups attached. After polymerization under 320 oC for 10 min, this layer could bond tightly around fiber. And TGA results demonstrated that polymerized layer had excellent heat-resistance and possessed an initial decomposition temperature over 400 °C. A microbond test was implemented to accurately evaluated the interfacial shear strength (IFSS), meanwhile, a facile approach of “spraying” was applied to form microdroplets in quantity onto single carbon fiber within a few minutes. It was found that the fiber and the matrix was efficiently bonded and the interaction was efficaciously enhanced by the polymeric layer, thus 20.9% of IFSS and 20.9% of bulk composites’ tensile strength improvement were achieved compared to those without modification. Notably, the in-situ polymerization formed a gradient transition of interfacial modulus and raised the interphase thickness to 800 nm, thus a “buffer” in interphase region was established. Our work provided a facile method to manufacture high-performance thermoplastic composite with outstanding interfacial property and broaden its application in advanced materials field.

Correction to: Synthesis of alternating semi-aromatic poly(ester amide)s and the amide transesterification

Correction to: Synthesis of alternating semi-aromatic poly(ester amide)s and the amide transesterification

Facile synthesis of eight-membered cyclic(ester-amide)s and their organocatalytic ring-opening polymerizations

Facile modular synthesis of eight-membered cyclic(ester-amide)s based on phthalic anhydride and β-amino alcohols and organocatalitic ROP of the monomers to afford degradable semi-aromatic poly(ester-amides)s with tunable thermal properties.

Synthesis of alternating semi-aromatic poly(ester amide)s and the amide transesterification

Synthesis of alternating semi-aromatic poly(ester amide)s and the amide transesterification

Synthesis and thermal and mechanical properties of nonisocyanate poly(ether urethane) thermoplastic elastomers containing dibutylene terephthalate and poly(tetramethylene ether) segments

Several novel semiaromatic poly(ether urethane) thermoplastic elastomers were synthesized through a nonisocyanate route. The nonisocyanate thermoplastic polyurethane elastomers (NI-TPUEs) were prepared via a transurethane polycondensation of bis(hydroxyethyl) hexanediurethane with bis(4-hydroxybutyl) terephthalate and poly(tetramethylene glycol)s under a reduced pressure of 3 mmHg at 170°C. The NI-TPUEs were fully characterized. The influence of hard segment (HS) contents on thermal and mechanical properties was studied. Gel permeation chromatography characterization demonstrated that high molecular weight of NI-TPUEs was obtained. Wide-angle X-ray scattering and thermal characterization verified that NI-TPUEs were crystallizable and had a relatively high melting point. Atomic force microscopy exhibited microphase separation between the crystallized HSs and amorphous phases. High content of HSs and flexible poly(tetramethylene ether) soft segments leads to good crystallization, excellent mechanical property, and good resilience of NI-TPUEs.

Increasing sustainability on the metallurgical industry by integration of membrane nanofiltration processes: Acid recovery

The metallurgical industry generates large volumes of toxic effluents characterised, generally, by high acidity and a noticeable content of metals (Fe, Cu and Zn) and non-metals (As, Sb, Bi). The toxicity of these streams makes necessary treatment before its discharge to the environment or reuse. Sustainable management of these effluents must be focused on the recovery of low added valuable by-products (e.g. strong acids) to reduce the wastes generated along with the treatment (e.g. sludge). Nanofiltration offers clear advantages for acid recovery instead of the conventional treatments such as neutralisation and precipitation, due to the high membrane transport ratios of single charged ions and high rejection of multi-charged ions. The performance of a semi-aromatic poly(piperazineamide) membrane (NF270) was evaluated for the treatment of effluents from copper metallurgical process streams of off-gases treatment trains. These streams are characterised by a high acidity (pH < 1) due to a mixture of strong (H2SO4, HCl) and weak (H3AsO4) acids and the presence of metallic species (Fe, Cu, Zn). The membrane performance was evaluated in terms of acid recovery and metal ions rejection taking into account their aqueous speciation in strong acid media. The transport of the species across the membrane was characterised according to the Solution-Electro-Diffusion model. The membrane permeances to aqueous species (both charged and non-charged) in strongly acidic solutions were calculated. NF270 showed good results for strong acid recovery, exhibiting high rejections of the metallic impurities. The implications of the presence of large amounts of As present as H3AsO4 should involve a selective removal stage using H2S or Na2S2O3.

Semiaromatic Poly(thioester) from the Copolymerization of Phthalic Thioanhydride and Epoxide: Synthesis, Structure, and Properties

We report a new semiaromatic poly(thioester) obtained through the copolymerization of phthalic thioanhydride and propylene oxide. The reaction was catalyzed by a chromium-based complex in conjuncti...

Thermal stability and structural anisotropy of semiaromatic poly(ester amides) from aromatic bis(2-oxazolines) and aliphatic dicarboxylic acids

Semiaromatic poly(ester amides) containing three different aromatic units and aliphatic spacers with five different chain lengths were investigated using various experimental methods, with a focus on the effect of structural changes in the mesogenic groups and the length of the flexible alkylene spacer on the observed physical properties. The results of thermal stabilities and crystallographic measurements indicate that the thermal stability is dependent on the content of the amorphous phase in the polymer. The results from the thermal stability, differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), and optical microscopy of the poly(ester amides) containing aromatic moieties were compared to the dielectric properties recorded using dielectric relaxation spectroscopy (DRS). DRS contributed to the description of four relaxation regions detected by matching the temperature and frequency dependencies of the dielectric functions. For the poly(ester amides) containing biphenyl units, the presence of a liquid-crystalline (LC) phase was observed.

High‐temperature copolyamides obtained by the efficient transamidation of crystalline–crystalline polyamide blends

ABSTRACTHigh‐performance thermoplastic composites based on semiaromatic polyamides are prime candidates for metal replacement in lightweight structural applications. However, the low ductility and toughness of semiaromatic polyamides remain major obstacles to their wider industrial application. In this study, we showed that novel random copolymers were formed by the unexpectedly efficient transamidation during the melt compounding of semicrystalline semiaromatic and aliphatic polyamides. Thus, homogeneous materials with a single glass transition and a high degree of crystalline order were obtained from blends of the semiaromatic poly(hexamethylene terephthalamide‐co‐isophthalamide) (PA6TI) with poly(hexamethylene adipamide) (PA66) or poly(hexamethylene sebacoamide) (PA610). By contrast, phase segregation and a less efficient transamidation was observed for cocompounded PA6TI and polylaurolactam (PA12). We attributed this to differences in the hydrogen‐bonding patterns of the two polyamides. This study opened the way for the preparation of novel high‐performance thermoplastic polyamides and composites through simple melt compounding. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44349.

Synthesis of highly transparent poly(amide–imide)s based on trimellitic acid and dependence of thermal properties on monomer sequence

Transparent, thermally stable, and semiaromatic poly(amide–imide)s were prepared from hydrogenated trimellitic anhydride chloride (h-TAC) with various aromatic diamines. The dependence of thermostability on the monomer sequence and terminal group was investigated. Thermogravimetric/differential thermal analysis (TG/DTA) was performed to evaluate the thermostabilities, which were found to be primarily affected by the monomer sequence in the polymer units. The 5% weight loss temperature (Td5) in N2, glass transition temperature (Tg), and cutoff wavelength of the ultraviolet–visible (UV–Vis) spectrum (λcut) of the semiaromatic poly(amide–imide)s are 422–456°C, 131–274°C, and 293–321nm, respectively, while those of wholly aromatic poly(amide–imide)s are 454–480°C, 169–287°C, and 415nm, respectively.

Composites of Semiaromatic Poly(Amide-Ester-Imide) Based on Bioactive Diacid and Oragnomodified Nanoclay Produced by Solution Intercalation Method: Thermal and Morphological Study

The aim of this work was to develop environmental friendly hydrophobic organomodified montmorillonite (OMMT) reinforced poly(amide-ester-imide) (PAEI) composites with enhanced their properties. At first, a chiral PAEI was obtained by step-growth polymerization of diol, N,N’-(1,3,5,7-tetraoxo-5,7-dihydropyrrolo[3,4-f]isoindole-2,6(1H,3H)-diyl)bis(4-hydroxybenzamide) with N-trimellitylimido-L-leucine. The blending of nanoclays with PAEI modifies the thermal property, and this change is strongly related to the dispersion of nanoclay in the polymer matrix. For this goal, positively charged chiral L-leucine was incorporated into the unmodified Cloisite-Na+ montmorillonite (MMT) for organomodification of MMT by cation-exchang method. Then PAEI/OMMT nanocomposites with different compositions were synthesized by solution intercalation method.

Synthesis and Characterization of Poly(ethylene terephthalamide/hexamethylene terephthalamide)

Semiaromatic poly(ethylene terephthalamide/hexamethylene terephthalamide) copolymer (PA2T/6T) was synthesized through the reaction of terephthaloyl chloride, 1,6-hexane diamine and 1,2-ethylene diamine by the method of interfacial polycondensation. The inherent viscosities of the resultant copolymers prepared with optimum synthesis conditions were 0.40–0.80 dL/g. The chemical structures of the copolymers were characterized by FT-IR and 1H-NMR. These copolymers had excellent thermal properties with melting temperatures (Tm) of 340–380°C and initial degradation temperatures (Td) of 390–440°C. The copolymers had wider processing temperature range than poly(hexamethylene terephthalamide) (PA6T), especially the copolymer which contained 60% 2T unit (2T mol% = 60%). At the same time, the ethylene diamine and hexane diamine is cheap which can decrease the costs of the materials. It suggests PA2T/6T is a promising heat resistant and processable engineering plastic.

Effect of membrane chemistry and coating layer on physiochemical properties of thin film composite polyamide RO and NF membranes: II. Membrane physiochemical properties and their dependence on polyamide and coating layers

The physiochemical properties of 17 widely used commercial RO and NF polyamide (PA) membranes were fully characterized by atomic force microscopy, transmission electron microscopy, contact angle measurement, streaming potential analysis, and flux and rejection performance tests. The surface properties (roughness, hydrophilicity, and surface charge) and bulk properties (permeability and rejection) were demonstrated to be highly inter-dependent, as all these were determined by the polyamide chemistry and any associated surface coating layer. The 1,3-benzenediamine and trimesoyl chloride based fully aromatic membranes had surface roughness on the order of 100 nm, an order of magnitude rougher than the semi-aromatic poly(piperazinamide) membranes. Furthermore, the uncoated fully aromatic membranes were significantly more hydrophobic (contact angles 43–49°) than the semi-aromatic ones (~30°). The presence of a neutral polyvinyl alcohol (PVA) coating layer can significantly enhance hydrophilicity and reduce surface charge and roughness for fully aromatic PA membranes, while its effect was only marginal for semi-aromatic poly(piperazinamide) membranes. The selectivity of a membrane appeared to be inversely related with its permeability. The highly permeable piperazine based membranes were much less selective than the fully aromatic ones. The salt rejection of a membrane was enhanced upon coating with a PVA layer, at the expense of reduced permeability. The current study suggests that the physiochemical properties can be used to diagnose the polyamide and coating chemistry, in addition to the conventional spectroscopic methods. Understanding such dependence of membrane properties and performances on their structure and chemistry might also be important for membrane synthesis, modification, and their applications in water and wastewater treatment.

Facile Synthesis of Semiaromatic Poly(amic acid)s from trans-1,4-Cyclohexanediamine and Aromatic Tetracarboxylic Dianhydrides

Facile Synthesis of Semiaromatic Poly(amic acid)s from <i>trans</i>-1,4-Cyclohexanediamine and Aromatic Tetracarboxylic Dianhydrides