Higher Melting Peak Research Articles

Ti-iminocarboxylate catalyzed polymerization of ethylene to highly crystalline, disentangled, ultrahigh molecular weight polyethylene

Disentangled ultrahigh molecular weight polyethylene (d-UHMWPE) is a niche, highly sought-after, and an emerging class of polyethylene. However, the synthesis of d-UHMWPE is uncommon and is equally challenging. Here, we report a Ti-iminocarboxylate complex that produces d-UHMWPE under ambient polymerization conditions. Treatment of tetrakis(dimethylamido-titanium) [Ti(NMe2)4] with 2-((4-methoxybenylidene)amino)benzoic acid produced a novel titanium complex Cat.1 [bis-dimethylamido-Ti-(bis-iminocarboxylate)]. The identity of Cat.1 was unambiguously ascertained using a combination of 1-2D NMR spectroscopy and mass analysis. Cat.1 was activated using various cocatalysts, and MMAO (modified methylaluminoxane) outperformed the others. Screening of polymerization parameters suggested an Al/Ti ratio of 1000, 4 bar ethylene pressure, 35 °C temperature, and a polymerization time of 30 min as the optimal condition. Under the optimized polymerization conditions, Cat.1 polymerizes ethylene to ultrahigh molecular weight polyethylene with a weight average molecular weight (Mw) of 2.5 × 106 g/mol. The thermal behavior of the thus prepared material disclosed a highly crystalline [crystallinity χ (DSC) 96 %], strictly linear polyethylene. Detailed thermal analysis of the nascent polyethylene using a specifically designed DSC method revealed the existence of a high melting peak at 139–140 °C, which is a hallmark of disentangled UHMWPE. Thus, a homogeneous, single-site ethylene polymerization catalyst has been developed, which upon activation with MMAO produced highly crystalline d-UHMWPE.

Improvement of physical and mechanical properties of electrospun poly(lactic acid) nanofibrous structures

The electrospinning of stereocomplexed poly(lactic acid) (Sc-PLA) twisted yarns was our approach to produce PLA-based nanofibrous structures with improved physical and mechanical characteristics for the applications as medical devices. An electrospinning apparatus consisted of two nozzles, and a take-up/twister unit was employed to fabricate twisted yarns through a continuous procedure. The yarn samples were produced via electrospinning of the solutions of high molecular weights poly(d-lactide) (PDLA) and poly(l-lactide) (PLLA) and also their blend solution at 1:1 ratio, and their physical and mechanical properties were compared. The morphological studies indicated that uniform yarns composed of bead-free and smooth fibers were formed. Electrospinning of the blend solution of PLLA/PDLA resulted in developing fibers and yarns with smaller diameters. The DSC analysis showed that the Sc-PLA yarn had a higher melting peak (at 230 °C) compared to PLLA and PDLA samples (184 °C), indicating the formation of stereocomplex crystallites in this sample. After isothermal heat treatment, the formation of the stereocomplex crystals in the electrospun Sc-PLA yarn was also confirmed by FTIR and WAXD analyses. Furthermore, because of the formation of stereocomplex crystallites during the electrospinning process, the stress-at-break and Young’s modulus of the yarns were enhanced, while the strain-at-break (%) was reduced. The current approach of stereocomplexation during the electrospinning procedure, and simultaneously, collecting the stereocomplexed nanofibers in the form of twisted yarn, can improve the inherent lack of physical and mechanical features of PLA nanofibrous structures for advanced applications as medical textiles.

Isothermal step thickening in a long-spaced aliphatic polyester

Discontinuous lamellar thickening has been found at the isothermal crystallization temperatures of a long-spaced aliphatic polyester (PE-48,48) synthesized via polycondensation of the diol and diacid. The isothermal step thickening is characterized by a discrete increase in melting temperature with increasing crystallization time and an increase in heat of fusion of the high melting peak at the expense of the low melting peak. The increase in crystal thickness, quantified by SAXS, is consistent with a straightening of the chains at the basal surfaces of the lamellae to complete a full repeat of the crystalline layer. The increase in thickness and decrease in surface energy are associated with the sudden increase in crystal melting. The isothermal thickening follows a logarithmic dependence of time with a rate that increases with temperature. The thickening process is thermally activated and follows Arrhenius behavior with an activation energy of 238 ± 4 kJ/mol.

Polyvinylidene fluoride (PVDF)-poly(methyl methacrylate) (PMMA)-expanded graphite (ExGr) conducting polymer blends: Analysis of electrical and thermal behavior

Polyvinylidene fluoride (PVDF)-20 wt% poly (methyl methacrylate) blend has been synthesized by solution blending method. Expanded graphite has been synthesized by microwave irradiation of commercial expandable graphite. With varying concentration of expanded graphite (ExGr) in PVDF-20 wt% PMMA, series of blends are synthesized. The electrical percolation threshold has been observed to be less than 1 wt% ExGr which is due to the formation of graphite nanosheets. The conducting blend system exhibits typical percolation behavior. The thermogravimetric analysis shows two step degradation in PVDF-20 wt% PMMA blend system. This is due to the individual degradation of PMMA and PVDF main chains respectively. The thermal stability of the blend system with 1 wt% ExGr incorporation in PVDF-20 wt% PMMA is increased by 11 °C corresponding to main chain degradation of PVDF. The result proves existence of strong interaction between ExGr particles and the polymer. The DSC analysis shows very clearly the existence of electroactive gamma phase both in PVDF-20 wt% PMMA with and without ExGr particles as there is an additional high temperature melting peak apart from that of the melting peak at 167 °C. This result is confirmed through XRD also. The blend system is characterized by XRD, TGA, DSC and FTIR.

Development of polylactide bead foams with double crystal melting peaks

In this study, we report the development of polylactide (PLA) bead foams with a double crystal melting peak structure. PLA bead foams with 3- to 30-fold expansion ratios and average cell sizes ranged from 350 nm to 15 μm were prepared. We found that the PLA's foam structure was significantly affected by the amount of perfected crystals (that is, crystals with a high melting temperature) generated during CO2 saturation. The structure was also affected by crystals with a low melting temperature that formed during foaming and cooling. Various CO2 pressures further influenced the crystallization kinetics of the crystals with a high melting temperature during the saturation. At various pressures, different crystallization kinetics also significantly affected the PLA foam's cell morphology and its uniformity. At a high saturation pressure, the increased content of dissolved CO2 in the PLA promoted the cell nucleation rate through the increased degree of thermodynamic instability. On the other hand, at high pressures, small-sized perfect crystals were induced as high-melting peak crystals. Thus, the heterogeneous cell nucleation around these crystals was further improved, which also caused the generation of a more uniform foam structure. Moreover, this study introduces this bead foam technology as an innovative new way to produce nanocellular foam products.

Cell Morphology and Improved Heat Resistance of Microcellular Poly(l-lactide) Foam via Introducing Stereocomplex Crystallites of PLA

The preparation of poly(l-lactic acid) (PLLA) foam with well-defined cell structure and high heat resistance is critical to broaden its applications. In this study, the stereocomplex crystallites (SC) with higher melting point and heat stability were introduced into PLLA foam by melt blending the PLLA with different amounts of poly(d-lactic acid) (PDLA). The crystal structures of pure PLLA and PLLA/PDLA blends formed during the blending and molding process were compared. It was found that no obvious crystallization was detected in pure PLLA, while SC formed in PLLA/PDLA blends. Crystal structure and morphology evolution of PLLA and PLLA/PDLA during the CO2 saturation and foaming process were investigated by combination of DSC, WAXD, FTIR, and SEM techniques. The results suggested SC had a higher melting peak, higher thermal stability, and smaller crystal domain size in relation to the homocrystal of PLLA, and it did not further develop with the CO2 saturation and the foaming processes, while the CO2 saturation induced the formation of the mesomorphic structure in PLLA and PLLA/PDLA blends. The mesomorphic structure transformed into the more stable α form in the following foaming process. The resultant PLLA/PDLA foam exhibited a significant and concurrent increase in cell density and cell structure uniformity relative to PLLA foam. The heat resistance measurement presented that thus-prepared PLLA/PDLA foams had better heat resistance than PLLA foam, which was attributed to the higher melting point, higher heat stability, and higher cell nucleation ability of SC in PLLA/PDLA foams.

Effect of OMMT on Morphology and Property of PTT/ASA Blends

Nanocomposites of poly(trimethylene-terephthalate)/poly(acrylonitrile-styrene-acrylate)/organic montmorillonite(PTT/ASA/OMMT) were prepared by means of melt-blending intercalation. The effect of OMMT contents on the phase morphology, crystallization behavior, rheological- and mechanicalproperties were investigated. The results show that the size of dispersed phases decreases with increasing OMMT content. The crystallization peak shifts to high temperature and melting peak moves to low temperature owing to the heterogeneous nucleation of OMMT. The exfoliated OMMT is located in the PTT matrix and at interface of PTT/ASA phases The rheological measurements show that the elastic modulus and complex viscosity increase with increasing OMMT content. The interfacial modulus and interfacial layer thickness predicted by Palierne and Gramspacher-Meissner models are enhanced by introduction of OMMT. The tensile strength and notched impact strength of blends increase with increasing OMMT content.

Monitoring batch lipase catalyzed interesterification of palm oil and fractions by differential scanning calorimetry

The melting profiles of palm oil, palm olein, and soft palm mid fraction were investigated by differential scanning calorimetry (DSC) before, during and after enzymatic interesterification. The DSC melting profiles of the three palm fats changed drastically due to the random redistribution of the fatty acids on the glycerol occurring upon interesterification. A high melting peak (already present for native palm oil) was observed for the three interesterified products and attributed to the increase in trisaturated triacylglycerols; modifications of the shape of the medium-melting peak (observed in the three products) were attributed to modifications within the mono-unsaturated triacylglycerols. In view of the drastic changes observed, the applicability of DSC to monitor enzymatic interesterification reactions was considered. While the degree of interesterification was supposed to be completed after 8 h according to the HPLC data, significant modifications were still observed within the DSC melting profiles. Minor changes within the structure of the medium-melting peak were selected as indicator of the reaction progress, and it was shown that intensities of DSC melting endotherms can be used to monitor the enzymatic interesterification reaction of these palm products.

Molecular Diagnosis of Fragile X Syndrome Using Methylation Sensitive Techniques in a Cohort of Patients With Intellectual Disability

BackgroundFragile X syndrome, the most common form of inherited intellectual disability, is caused by expansion of CGG trinucleotide repeat at the 5′ untranslated region of the FMR1 gene at Xq27. In affected individuals, the CGG repeat expansion leads to hypermethylation and the gene is transcriptionally inactive. Our aim was to identify fragile X syndrome among children with intellectual disability in Saudi Arabia. Patients and MethodsThe study included 63 patients (53 males, 10 females) presented with intellectual disability, 29 normal subjects, and 23 other family members. DNA samples from six patients previously diagnosed with fragile X syndrome by Southern blot technique were used as positive controls. The method was based on bisulfite treatment of DNA followed by two different techniques. The first technique applied polymerase chain reaction amplification using one set of primers specific for amplifying methylated CpG dinucleotide region; another set designed to amplify the unmethylated CGG repeats. The second technique used the methylation-specific melting curve analysis for detection of methylation status of the FMR1 promoter region. ResultsMolecular testing using methylation sensitive polymerase chain reaction had shown amplified products in all normal subjects using unmethylated but not methylated primers indicating normal alleles, whereas amplified products were obtained using methylated polymerase chain reaction primers in fragile X syndrome–positive samples and in 9 of 53 males, indicating affected individuals. Molecular testing using melting curve analysis has shown a single low melting peak in all normal males and in (44/53) patients indicating unmethylated FMR1 gene, whereas high melting peak indicating methylated gene was observed in the fragile X syndrome–positive samples and in 9 of 53 patients. We found 100% concordance between results of both techniques and the results of Southern blot analysis. Three samples have shown both methylated and unmethylated alleles, indicating possible mosaicism. No female patients or carriers could be detected by both techniques. ConclusionThe technique can be applied for the rapid screening for fragile X syndrome among patients with intellectual disability. The impact of mosaicism on clinical severity needs further investigation.

Nylon 66 nanofibers prepared by CO2 laser supersonic drawing

ABSTRACTNylon 66 nanofibers were prepared by irradiating as‐spun nylon 66 fibers with radiation from a carbon dioxide (CO2) laser while drawing them at supersonic velocities. A supersonic jet was generated by blowing air into a vacuum chamber through the fiber injection orifice. The fiber diameter depended on the drawing conditions used, such as laser power, chamber pressure, laser irradiation point, and fiber supply speed. A nanofiber obtained at a laser power of 20 W and a chamber pressure of 20 kPa had an average diameter of 0.337 μm and a draw ratio of 291,664, and the drawing speed in the CO2 laser supersonic drawing was 486 m s−1. The nanofibers showed two melting peaks at about 257 and 272°C. The lower melting peak is observed at the same temperature as that of the as‐spun fiber, whereas the higher melting peak is about 15°C higher than the lower one. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014, 131, 40015.

Steam-Chest Molding of Expanded Polypropylene Foams. 1. DSC Simulation of Bead Foam Processing

To investigate the evolution of melting behavior during the steam-chest molding process of expanded polypropylene (EPP) bead, a differential scanning calorimetry (DSC) test involving fast heating, isothermal treatment, and fast cooling was used to simulate the bead foam processing. The EPP bead foam had two original melting peaks: a low melting peak, Tmlow, and a high melting peak, Tmhigh. A new melting peak, Tmi, was induced in the DSC curves, resulting from the heating process, when the treatment temperature was 80−150 °C. The Tmi was about 7 °C higher than the treatment temperature and tended to increase linearly with the increased treatment temperature. A new melting area and further a melting peak, Tmc, were observed in DSC curves, resulting from the cooling process, when the treatment temperatures were higher than 135 °C. The high sensitivity of the Tmi and Tmc to treatment temperature provided a clue to the actual temperature inside the mold during the steam-chest molding process. Different steam pressures were applied during EPP bead processing, and the melting behavior of molded EPP samples was measured to check the processing thermal history. A comparison study was done between the DSC simulations and the actual results to understand the melting behavior evolution of EPP bead foam during processing. Some fundamental issues in the steam-chest molding processing, such as the actual steam temperature, the temperature gradient across the mold cavity, and the accurate pressure parameter used to describe the actual processing temperature were also studied based on the DSC simulation.

Thermal characterization of the HDPE/LDPE blend (10/90) irradiated using γ-rays

Gamma irradiation effect over the properties of slow cooled and fast cooled HDPE/LDPE 10/90 blend was studied. The blend and the neat polyethylenes were irradiated at room temperature in the presence of air using the following doses (4.8 kGy/h): 0, 50, 150, 400 and 1000 kGy. Differential scanning calorimetry (DSC) experiments were carried out using the following heating rates: 5, 10 and 20 °C/min. DSC results for the slow and fast cooled blend showed traces with three melting peaks and with increasing irradiation dose two melting peaks were obtained, i.e. the high melting peak shifts toward lower temperatures to merge with the intermediate melting peak into one endotherm. No changes in crystal structure by X-ray diffraction were found as a result of samples irradiation. Radiation crosslinking prevents crystal rearrangements during heating in the DSC. Gel content and melt flow index (MFI) measurements showed that radiation induced a high degree of crosslinking for all samples; gel content values were above 50% and a drop of more than 90% in the MFI was found. Irradiation of slow cooled samples resulted in larger values of gel content and lower MFI values than for fast cooled samples, mainly because of the higher degree of crosslinking for the former.

Effect of a Miscible Polymeric Diluent on Complex Formation between Isotactic and Syndiotactic Poly(methyl methacrylate)

Formation of a stereocomplex structure in a blend of isotactic and syndiotactic poly(methyl methacrylate)s (iPMMA/sPMMA) was found to be significantly enhanced by introducing a mutual miscible diluent of poly(ethylene oxide) (PEO) in the blend, even when prepared using a kinetically hindered noncomplexing CHCl3 solvent. Mechanisms and influencing factors, such as thermal treatment, annealing temperature, annealing time, or PEO content in blends, on structures of stereocomplexes in the ternary iPMMA/sPMMA/PEO blends are discussed. WAXD result showed that addition of PEO in the iPMMA/sPMMA blend did not alter the crystal cells in the complexes. Melting peaks associated with the complexes were analyzed for discerning possible structural mechanisms. When annealed at specific temperatures, multiple endothermic peaks of the complexes increased in intensity as PEO contents increased in the ternary blends. Analysis shows that the lower melting peak (P1) represents shorter stereocomplex sequences or stereocomplex detached from PEO or connected with partial PEO, but the higher melting peak (P3) is related to the stereocomplex physically interconnected in the presence of PEO. The PEO molecules are thought to more easily interact with the stereocomplexes in blends by acting as a plasticizer, which decreases Tg of the more rigid PMMA chain segments. Physical interaction or miscibility-enhanced chain entanglement probably exists between PEO and the stereocomplex of tactic PMMAs, leading to stereocomplex formation in the iPMMA/sPMMA/PEO ternary blend. FT-IR characterization provided evidence of weak interactions between PEO and the stereocomplex of PMMA. IR peaks sensitive to complex structures with respect to temperature were analyzed for discerning effects by adding PEO. The stereocomplex formation of ternary blends with PEO is due to the weak interaction of ester groups and methoxy groups between PMMA and PEO.

Analysis of multiple melting behavior of spherulites comprising ring‐band shell/ringless core in polymorphic poly(butylene adipate)

AbstractIn‐depth interpretation of ring‐banded spherulitic morphology, crystals, polymorphism, and complex melting behavior in poly(1,4‐butylene adipate) (PBA) were analyzed via a procedure of designing composite core‐shell spherulites, in which two lamellar patterns (ring‐band vs. ringless) were packed by subjecting to crystallization at two‐step temperature schemes with specific temperatures and times. By heating to 52 °C and holding at that temperature for 30 min annealing, the core can be stripped off by melting, and analysis specifically on the ring‐shell portion (with the ringless core stripped by controlled melting) proves that the highest melting peak (P4 at 55–57 °C) is likely associated with melting of the ring‐band lamellae. Furthermore, the unusually complex multiple melting in PBA can be attributed to all three widely proposed mechanisms: (1) multiple types of lamellae preexisting in crystallized PBA, (2) scan/heating induced remelting/reorganization, and (3) polymorphism of dual crystal cells. In addition, this study evidently shows that the extinction rings within the ring‐banded shell, regardless of alternate edge‐on and flat‐on mechanism or alternative origins, can be of all singly α‐crystal form, either initially or upon postheating temperature‐induced transformation. Thus, the type of crystal forms (α or β) in polymorphic PBA is mainly associated with temperature of crystallization (Tc = 28 or 35 °C), and not likely with lamellar orientation (flat‐on or edge‐on). © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 892–899, 2008

Shear-induced crystallization of poly(phenylene sulfide)

The crystalline morphology of poly(phenylene sulfide) (PPS) isothermally crystallized from the melt under shear has been observed by polarized optical microscope (POM) equipped with a CSS450 hot-stage. The shish–kebab-like fibrillar crystal structure is formed at a higher shear rate or for a longer shear time, which is ascribed to the tight aggregation of numerous oriented nuclei in the direction of shear. The crystallization induction time of PPS decreases with the shear time, indicating that the shear accelerates the formation of stable crystal nuclei. Under shear, the increase of spherulite growth rate results from highly oriented chains. The melting behavior of shear-induced crystallized PPS performed by differential scanning calorimetry (DSC) shows multiple melting peaks. The lower melting peak corresponds to melting of imperfect crystal, and the degree of crystal perfection decreases as the shear rate increases. The higher melting peak is related to the orientation of molecular chains. These oriented molecular chains form the orientation nuclei which have higher thermal stability than the kebab-like lamellae that are developed later. A new model based on the above observation has been proposed to explain the mechanism of shish–kebab-like fibrillar crystal formation under shear flow.

Crystallization and melting behaviors of polystyrene- b-poly(ethylene- co-butene) block copolymers

Non-isothermal and isothermal crystallization behaviors of polystyrene- b-poly(ethylene- co-butene) (PSt- b-PEB) block copolymers with different compositions and chain lengths were investigated by differential scanning calorimetry (DSC). The results show that crystallization of PEB block is strongly dependent on the composition. Crystallization temperature ( T c), melting temperature ( T m) and fusion enthalpy (Δ H f) increase rapidly with PEB volume fraction ( V E) for block copolymers with V E below 50%, but there is little change when PEB block becomes the major component. Glass transition temperature ( T g) of the PSt block and order–disorder transition temperature ( T ODT) of block copolymers also have a weak effect. The isothermal crystallization kinetics results show that Avrami exponent ( n) was strongly dependent on the composition and crystallization temperature. For the block copolymers with V E below 38.7 vol%, the values of n vary between 0.9 and 1.3, indicating that crystallization is confined. For the PSt- b-PEB block copolymers with V E higher than 50%, fractionated crystallization behavior is usually observed. A two-step isothermal crystallization procedure is applied to these block copolymers. It is found that breakout crystallization occurs at higher T c, but confined at lower T c. Two overlapped melting peaks are observed for the block copolymers with fractionated crystallization behavior after two-step crystallization, and only the higher melting peak corresponding to breakout crystallization can be used to derive equilibrium melting temperature.

Crystallization Kinetics and Melting Behavior of PA1010/Ether-based TPU Blends

Polyamide 1010 (PA1010)/thermoplastic poly (ether urethane) elastomer (ether-based TPU) blends were prepared via melt extrusion. The crystallization kinetics and melting behavior of PA1010/ether-based TPU blends were systematically investigated using differential scanning calorimetry. The crystallization kinetics results show that the addition of ether-based TPU hinders the crystallization of PA1010, and the hindrance effect increases with the increase of the concentration of ether-based TPU. Both pure PA1010 and PA1010/ether-based TPU blends exhibit double melting peaks in the process of nonisothermal crystallization. The double melting peaks change differently with the variation of cooling rate and blend composition. The cooling rate only influences the lower melting peak; however, the blend composition influences not only the lower melting peak but also the higher melting peak. The reason for the phenomenon must be the interaction between the two compositions.

A Homogeneous Assay for Analysis of FMR1 Promoter Methylation in Patients with Fragile X Syndrome

Fragile X syndrome is caused by the expansion of a CGG trinucleotide repeat at the 5' untranslated region of the fragile X mental retardation 1 gene (FMR1). When expanded to >200 repeats (full mutation), the repeat region and the adjacent promoter CpG island become hypermethylated, rendering FMR1 transcriptionally inactive. Conventional molecular diagnosis of fragile X syndrome involves determination of the CGG repeat number by Southern blot analysis. A homogeneous methylation-specific melting curve analysis (MS-MCA) assay for methylation status of the FMR1 promoter region was developed on the LightCycler platform. Genomic DNA was treated with sodium bisulfite, and a region containing 8 CpG sites was amplified in the presence of SYBR Green I, using primers that do not differentiate between methylated and unmethylated FMR1 molecules. After amplification, the samples were melted at 0.05 degrees C/s, and fluorescence melting curves were recorded. We studied samples, previously characterized by Southern blot analyses, from 10 female and 10 male donors with normal numbers of CGG trinucleotide repeats, 9 male donors who were premutation carriers, 4 male donors who carried both a premutation and a full mutation, and 25 patients with fragile X syndrome. Samples from all 20 male patients with fragile X syndrome showed a high melting peak corresponding to fully methylated FMR1, whereas samples from healthy males showed a single low melting peak corresponding to unmethylated FMR1. Of 24 samples from affected males, 9 (38%) showed 2 melting peaks, suggesting that cellular methylation mosaicism is common in fragile X syndrome. MS-MCA allows rapid and reliable identification of fragile X syndrome in male patients.

Crystallization and melting behaviour of poly(m-xylene adipamide)

The melting and crystallisation behaviour of poly(m-xylene adipamide) (MXD6) are investigated by using the conventional DSC, X-ray diffraction and polarised light microscopy. Triple, double or single melting endotherms are obtained in subsequent heating scan for the samples after isothermal crystallisation from the melt state at different temperatures. The lowest melting peak can be ascribed to the melting of secondary crystals. The melting of primary crystals causes the medium melting peak and the highest melting peak is attributed to the melting of recrystallised species formed during heating. Following the Hoffman–Weeks theory, the equilibrium melting temperature is equal to 250°C and the equilibrium melting enthalpy ΔH m 0 to 175 J g–1. Then, using the Lauritzen–Hoffmann theory of secondary crystallisation, the analyse of the spherulitic growth shows that the temperature of transition between the growing regimes II and III is equal to 176°C. Finally the Gibbs-Thomson relationship allows the determination of the distribution function of crystalline lamellae.

Thermal transition behaviors in a liquid crystalline polyesterimide

The crystallization and melting behaviors of the polyesterimide, derived from N, N′-hexane-1,6-diylbis(trimellitimides), 4,4′-dihydroxybenzophenone and p-hydroxybenzoic acid, were investigated by using polarized light microscopy (PLM), differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXD). The nematic texture of the polyesterimide was observed on raising temperature to 265 °C, and the nematic phase was found to convert to isotropic melt beginning from about 300 °C, the ordered nematic micro-domains still surviving after 320 °C. Isothermal crystallization of the samples was performed at 180 °C after heating samples at various temperatures in the range of 265–360 °C, and a completed crystallization peak can appear on DSC curves up to the heating temperature of 360 °C in the presence of the nematic phase and the ordered nematic micro-domains. Non-isothermal crystallization of the samples at different cooling rate was carried out, and the melting of the resulting crystals exhibits double endotherms. It is indicated that a fast crystallization in the nematic phase forms relatively more ordered crystals, which melt at higher temperature, and a slow crystallization in the isotropic phase or in the biphasic melt produces poor crystals, which melt at lower temperature. The crystallized polyesterimide was annealed, which has a minor effect on the high-melting peak but leads to a continual shifting of the low-melting peak to higher temperature with increasing annealing temperature or annealing time. WAXD patterns indicated that the structural transform was not found during annealing process.