Copoly(1,3,4-oxadiazole-ether)s containing phthalide groups and thin films made therefrom

A series of aromatic copolyethers containing 1,3,4-oxadiazole rings and phthalide groups was prepared by nucleophilic substitution polymerization technique of phenolphthalein, 1, or of an equimolecular amount of 1 and different bisphenols 2, such as: 4,4′-isopropylidenediphenol, 4,4′-(hexafluoroisopropylidene)diphenol, 4,4′-(1,4-phenylene-diisopropylidene)bisphenol, 4,4′-cyclohexylidene-bisphenol and 2,7-dihydroxynaphthalene, with 2,5-bis(p-fluorophenyl)-1,3,4-oxadiazole, 3. The polymers were easily soluble in polar solvents such as N-methylpyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide and chloroform and can be cast from solutions into thin flexible films. They showed high thermal stability, with decomposition temperature being above 400 °C. The polymers exhibited a glass transition temperature in the range of 220-271 °C, with reasonable interval between glass transition and decomposition temperature. Electrical insulating properties of some polymer films were evaluated on the basis of dielectric constant and dielectric loss and their variation with frequency and temperature. The values of the dielectric constant at 10 kHz and 20 °C were in the range of 2.98-3.15.     

Mechanical and Thermal Properties of Poly(Phthalazinone Ether Sulfone)/Poly(Ether Sulfone) Blends

The mechanical and thermal properties of poly(phthalazinone ether sulfone) (PPES)/poly(aryl ether sulfone) (PES) blends prepared by melt-mixing were investigated by dynamic mechanical thermal analysis (DMTA) and thermogravimetric analysis (TGA). The dynamic mechanical thermal analysis results show that the incorporated PES has a large influence on the heat stability of PPES. The DMTA results display that the blends with a single glass transition temperature, which increases with increasing PPES content, indicates that PPES and PES are completely miscible over the studied composition range. The thermodegradative behavior of PPES/PES blends was used to analyze their thermal stability. The Friedman technique was used to determine the kinetic parameters (i.e., the apparent activation energy and order of reaction of the degradation process). The results indicate that the presence of the PES component influences the thermal stability of the PPES. On the basis of the kinetic data derived from Friedman' approach, the lifetime estimates for pure PPES, pure PES, and the blends generated from the weight loss of 5% were constructed.     

Mechanical Properties of Poly(Butylene Succinate) Reinforced with Continuously Steam-Exploded Cotton Stalk Bast

Poly(butylene succinate) (PBS) was reinforced by cotton stalk bast fibers (CSBF), which had been pretreated by the continuous steam explosion method. The influence of water content in CSBF during the explosion and fiber content on the mechanical properties of CSBF/PBS biocomposites was investigated. The results showed that the incorporation of CSBF decreased the tensile and impact strength, while significantly enhanced the flexural strength, flexural modulus and tensile modulus. The mechanical properties of biocomposites reinforced by exploded fibers were much better than that of the biocomposites reinforced by non-exploded fibers. Biocomposites reinforced by fibers with 40 and 50 wt% water contents during the explosion had the best mechanical properties. The morphology of CSBF and biocomposites was evaluated by SEM, which demonstrated that fibers with 40 and 50 wt% water contents had better separation and rougher microsurfaces, indicating a better adhesion between PBS matrix and fibers.     

Synthesis and properties of poly(amide-imide)s based on 1,5-bis(4-trimellitimido)naphthalene

1,5-Bis(4-trimellitimido)naphthalene (II) was prepared by the condensation reaction of 1,5-naphthalenediamine and trimellitic anhydride. A series of aromatic poly(amide-imide)s (IV _a–o) was synthesized by the direct polycondensation of the diimide-diacid (II) and various aromatic diamines (III _a–o). The reaction utilized triphenyl phosphite and pyridine as condensing agents in the presence of calcium chloride in N-methyl-2-pyrrolidone (NMP). The inherent viscosities of the resulting poly(amide-imide)s were in the range of 0.55∼1.39 dL/g. These polymers were generally soluble in polar solvents, such as N,N-dimethylacetamide (DMAc), NMP, N,N-dimethylformamide (DMF). Flexible and tough poly(amide-imide) films were obtained by casting from a DMAc solution and had tensile strengths of 90∼145 MPa, elongations to break of 5∼13 %, and initial moduli of 2.29∼3.73 GPa. The glass transition temperatures of some poly(amide-imide)s were recorded in the range of 206∼218 °C, and most of the polymers did not show discernible glass transition on their DSC traces. The 10% weight loss temperatures were above 522 °C in nitrogen and above 474 °C in air atmosphere.     

Synthesis and characterization of new soluble cardo poly(amide-imide)s derived from 2,2-bis[4-(4-trimellitimidophenoxy)phenyl]norbornane

A series of new soluble poly(amide-imide)s were prepared from the diimide-dicarboxylic acid, 2,2-bis[4-(4-trimellitimidophenoxy)phenyl]norbornane, and various diamines by the direct polycondensation in N-methyl-2-pyrrolidinone containing CaCl_2, using triphenyl phosphite and pyridine as condensing agents. All the polymers were obtained in quantitative yields with inherent viscosities of 1.01-1.42 dL g⁻¹. Gel permeation chromatography (GPC) of the polymers showed number-average and weight-average molecular weight up to 67,300 and 118,000, respectively. The poly(amide-imide)s were amorphous and were readily soluble in various solvents such as N-methyl-2-pyrrolidinone (NMP), N,N-dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), dimethylsulfoxide (DMSO), pyridine, cyclohexanone and tetrahydrofuran. Tough and flexible films were obtained by casting their DMAc solution. The films had tensile strength of 89-110 MPa and a tensile modulus range of 1.8-2.2 GPa. The glass transition temperatures of the polymers were determined by DSC method and they were in the range of 265-295 °C. The polymers were fairly stable up to a temperature around or above 450 °C, and lose 10% weight in the range of 472-504 °C and 490-520 °C in nitrogen and air, respectively.     

Mechanical and Thermal Properties of Poly(phthalazinone biphenyl ether sulfone)/PEEK Blends

A series of blends with various compositions are prepared by melt extrusion on the basis of novel copoly(phthalazinone biphenyl ether sulfone) (PPBES) and poly(ether ether ketone) (PEEK). The melt flowability, mechanical and thermal properties of the blends are studied. The results show that the incorporated PEEK has a large influence on the melt viscosity and thermal stability of blends. The tensile strength of the blends remains at about 90 MPa at room temperature; PPBES improves the mechanical properties of PEEK at 150°C. The flexural strength and modulus of the PPBES/PEEK blends also increase with the addition of PEEK.     

Novel Sepiolite-based Poly(Amide-imide) Nanocomposites: Preparation and Properties

Novel sepiolite-based poly(amide-imide) nanocomposites were prepared by in-situ polymerization via polycondensation of a diamine containing amide groups with hexafluoropropane dianhydride. The process involved dispersion of sepiolite in poly(amic acid) solution followed by thermal imidization to get ultimate nanocomposites. The morphology, thermal and mechanical performances of nanocomposites with various sepiolite contents were studied. Nanoparticles were homogenously dispersed throughout the matrix with 50–65 nm size range. Due to such dispersion, poly(amide-imide)-sepiolite nanocomposite films exhibited improvements on the thermal-mechanical properties. The best results arose from favorable miscibility between polymer and sepiolite in the nanocomposites when 3 wt.% nanoparticles were introduced into poly(amide-imide) matrix.     

Dispersion of Surface Modified Nanostructure Zinc Oxide in Optically Active Poly(Amide-Imide) Containing Pyromellitoyl-bis-L-isoleucine Segments: Nanocomposite Preparation and Morphological Investigation

Optically active zinc oxide/poly(amide-imide) (PAI) nanocomposites (NC)s were synthesized by using ultrasonic assisted technique. The polymers and zinc oxide (ZnO) nanoparticles were physically and/or chemically connected with each other through different kinds of interactions such as physical van der Waals forces, hydrogen bonding and/or covalent interactions. ZnO/PAI NCs were characterized by Fourier transform infrared spectra, X-ray diffraction patterns, and field emission scanning electron microscopy. The thermal stability studies indicated an enhancement of thermal stability of new NC materials compared with the pure polymer.     

Enhancing the PLA Crystallization Rate and Mechanical Properties by Melt Blending with Poly(styrene-butadiene-styrene) Copolymer

Poly(styrene-butadiene-styrene) (SBS) copolymer was used to enhance the crystallization ability and mechanical properties of poly(L-lactic acid) (PLA) through melt mixing. The thermogravimetric analysis and Fourier transform infrared results revealed the n–π interaction between PLA and SBS. Differential scanning calorimetry and X-ray diffraction analysis indicated that the crystallization ability of the PLA improved substantially. The PLA crystallized completely during the cooling process when the SBS content in the blend was above 20 wt.%. The elongation at break and the impact resistance were significantly improved compared with that of neat PLA when the SBS content was above 50 wt.%.     

Dielectric and Mechanical Relaxational Behavior of Poly (Chlorobenzyl Methacrylate)s

Dielectric relaxational behavior of poly(monochlorobenzyl methacrylate)s (PMClBM) and poly(dichlorobenzyl methacrylate)s (PDClBM) has been analyzed. The study was carried out by determining the components of the complex dielectric permittivity *. Two relaxation processes, labelled as α and β relaxations, which were analyzed in terms of the Havriliak-Negami and Cole-Cole equations, respectively, have been experimentally observed. The relative position of the chlorine substitute in the benzyl ring determines the characteristic parameters of the relaxations. Complementary dynamic mechanical measurements on these polymers have been carried out. The relationship between the macroscopic measurements with the dipolar moment of the relaxing entities has been analyzed in terms of the Onsager-Kirkwood-Fröhlich equation.     

耐高温新型含杂萘联苯聚醚砜嵌段共聚物的性能

将氯端基聚醚醚砜齐聚物和杂萘联苯类双酚羟端基齐聚物通过溶液缩聚,成功地合成了一系列新型聚醚醚砜-聚醚砜(PEES-PPES)嵌段共聚物,并用IR、DSC、TGA、X-WAXD等测试手段对聚合物进行了表征。结果表明:PEES-PPES具有较高的热稳定性,较好的溶剂溶解性;砜基比例的变化对PEES-PPES的热性能有较大的影响,表明砜基对杂萘联苯聚醚砜改性效果明显。     

Mechanical Properties of Benzoylated Oil Palm Empty Fruit Bunch Short Fiber Reinforced Poly(vinyl chloride) Composites

The influence of untreated and benzoylated oil palm empty fruit bunch (OPEFB) short fiber loading on the mechanical properties of the poly(vinyl chloride) (PVC) composite was studied. Benzoylated OPEFB was produced by mixing OPEFB with NaOH solution and agitating vigorously with benzoyl chloride. The PVC resin, various additives, and OPEFB were first dry blended using a laboratory mixer before being milled into sheets on a two-roll mill at 165°C and then hot pressed into composite samples at 180°C. The tensile and impact strength of untreated and benzoylated OPEFB composites decreased whereas the tensile modulus increased with increasing fiber loading from 0 to 40 phr. However, the benzoylated OPEFB was able to improve the tensile properties and impact strength of composites when compared to the untreated fiber. The enhancement of mechanical properties showed that the treatment improved the OPEFB fiber-PVC matrix interfacial adhesion. The improvement of adhesion was clarified by SEM micrographs, the increase of water resistance, and the reduction of glass transition temperature of the composites.     

抗聚结MBS的制备及性能

通过分子结构设计,合成了一系列提高MBS粉末特性的包裹剂,研究了抗聚结新型MBS的制备工艺以及包裹剂化学结构对MBS粉末特性及PVC／MBS共混物力学性能的影响。结果表明,加入包裹剂后,MBS粉末流动性及其堆积密度均有较大提高,而且显著提高PVC／MBS共混物的抗冲强度和抗拉强度。     

Synthesis of Diimide-Diacid Monomers and Poly(amideimide)s: Effects of Flexible Linkages and Pendant Hexafluoroisopropylidine Unit on Processability,Thermal Stability and Electrical Properties

Two diimide-diacid monomers N,N′-bis(4-carboxypheny-4-oxyphenyl)oxydiphthalimide and N,N′-bis(4-carboxyphenyl-4-oxyphenyl)4,4′-(hexafluoroisopropylidene)diphthalimide were synthesized and characterized by IR and ¹H-NMR. A series of poly(amideimide)s were prepared by direct polycondensation of diimide-diacids with aromatic diamines through phosphorylation reaction. The poly(amideimide)s were characterized by IR, XRD, TGA, DSC, solution viscosity, solubility studies and electrical properties. X-ray diffraction studies indicate that the poly(amideimide)s were amorphous. Poly(amideimide)s were soluble in common organic solvents and exhibit excellent thermal stability. The PAIs have electrical insulation character and can be used in insulation of electrical items operating at elevated temperatures.     

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.     

Novel Optically Active Poly(amide-imide)s Derived from N-Trimellitylimido-L-Isoleucine and Different Diisocyanates

Summary  A new class of optically active poly(amide-imide)s was synthesized via direct solution polycondensation of different aliphatic and aromatic diisocyanates with a chiral diacid monomer. The polymerization of N-trimellitylimido-L-isoleucine (TMIIL)(1) as an aromatic-aliphatic diacid monomer with 4,4’-methylenebis(phenyl isocyanate) (MDI)(2) was carried out by graduate heating as well as refluxing method in the presence of pyridine (Py), dibutyltin dilaurate (DBTDL), triethylamine (TEA) as a catalyst and without catalyst, respectively. In these solution polycondensations we used amino acids as chiral inducing agents. The optimized polymerization conditions of MDI were used for the polymerization of isophorone diisocyanate (IPDI)(3), tolylene-2,4-diisocyanate (TDI)(4), and hexamethylene diisocyanate (HDI)(5). The resulting polymers have inherent viscosities in a range of 0.17–0.48 dL/g. These polymers are optically active, thermally stable and soluble in amide type solvents.     

Synthesis and characterization of poly (amide-imide-imide)s based on diacids with bulky m-chloro phenyl moiety and rigid pyridine moiety

A series of novel aromatic diamines containing kinked m-chloro phenyl moiety was synthesized by the reaction of m-chloro benzaldehyde with 2,6-dimethyl aniline. The tetraimide diacid was synthesized by using the prepared diamine with benzophenone tetracarboxylic acid dianhydride (BPTDA) and p-amino benzoic acid. The polymers were prepared by treating the tetraimide diacid with different aromatic diamines. The structures of the monomers and polymers were identified by ¹H-NMR, FTIR,¹³C-NMR and elemental analysis. The polymers showed excellent thermal stability, solubility and mechanical properties. Their structure–property relationship was studied by comparing these m-chloro polymers with polymers containing rigid Pyridine moiety.     

Mechanical Properties of Silane and Zirconate Coupling Agent-Treated Oil Palm Empty Fruit Bunch Fiber-Filled Acrylic-Impact Modified Poly (Vinyl Chloride) Composites

The influence of untreated and treated OPEFB content on the mechanical properties of acrylic impact-modified PVC was investigated. The formulations were first dry blended before being milled into sheets on a two-roll mill. Test specimens were then hot pressed. The modulus significantly increased while the impact and flexural strength insignificantly improved with increasing of treated OPEFB contents. The reduction in water absorption, the formation of new absorption bands and the slight number of treated fiber pulled-out proved that there was an interaction between fiber and matrix. However, this interaction was insufficient to enhance the impact and flexural strength significantly.     

Thermostable soluble aromatic poly(amide-imide)s having hexafluoroisopropylidene and ether links in the main chain

An imide-containing dicarboxylic acid, 2,2-bis[4-(4-trimellitimidophenoxy)phenyl]-hexafluoropropane (I), was prepared by the condensation of 2,2-bis[4-(4-aminophenoxy)phenyl]-hexafluoropropane and trimellitic anhydride. A series of new hexafluoroisopropylidene-containing poly(amide-imide)s having inherent viscosities of 0.64–1.44 dL/g were prepared by the direct polycondensation of diimide-diacid I with various long-chain aromatic diamines using triphenyl phosphite and pyridine as condensing agents in N-methyl-2-pyrrolidone in the presence of calcium chloride. Most of the resulting poly(amide-imide)s were noncrystalline and showed good solubility in polar organic solvents. Almost all polymers afforded transparent, flexible, and tough films. The 10 % weight loss temperatures of these polymers were all above 499 °C, and the glass transition temperatures were in the range of 203–277 °C.     

Poly(ether-ester)s modified with different amounts of fumaric moieties

A series of novel poly(ether-ester)s modified with fumaric moieties is synthesized by transesterification in the melt of dimethyl terephthalate (DMT), dimethyl fumarate (DMF), 1,4-butanediol (BD) and poly(tetramethylene oxide) (PTMO, M?_n=1000 g/mol). The effect of the introduction of double bonds into both the hard and soft segments and their content on the structure and the thermal and rheological properties of the synthesized polymers are investigated. The introduction of double bonds into the polymer main chains increases the molecular weight of the copolyesters, but reduces the crystallinity of the hard segments and related properties such as modulus and hardness. The presence of double bonds improves the high temperature properties and thermal stability, especially the thermo-oxidative one, lowers the melting and crystallization temperature and increases the glass transition temperature. The incorporation of fumaric moieties into the macrochains improves the adhesive strength of the polymer to a metal surface.