Number-average Molecular Mass Research Articles

Preparation and wear resistance of water-based UV curable ink

ABSTRACT UV water-based inks have disadvantages such as slow curing speed and low degree of crosslinking. In this paper, the copolymer P(MMA-r-HEMA) was prepared by traditional free radical polymerization using methyl methacrylate (MMA) and hydroxyethyl methacrylate (HEMA) as monomers, and the copolymer P(MMA-r-HEMA) was modified by acrylic acid (AA) to synthesis completely water-soluble acrylic prepolymer P(MMA-r-HEMA)-g-AA. Triethylenetetramine reacted with glycidyl methacrylate (GMA) to yield a multifunctional reactive diluent TGMA. Secondly, acrylic prepolymer P(MMA-r-HEMA)-g-AA, multifunctional reactive diluent TGMA and photoinitiator were used to prepare water-based UV curable ink. The influence of the type and quality of photoinitiator, the relative molecular weight and mass fraction of P(MMA-r-HEMA)-g-AA, the number of functional groups and mass fraction of TGMA on the UV ink curing speed and the wear resistance of the ink film were discussed. When the mass fraction of the photoinitiator TPO was 1%, the number-average relative molecular mass of the prepolymer was 1.67 × 104 g/mol and the mass fraction was 60%, the number of functional groups of the reactive diluent was 6 and the mass fraction was 40%, the light curing of UV water-based ink was completed in 0.1 s, and the mass loss after 50 times abrasion was 0.2–0.4%.

Isolation and characterization of a nephroprotective polysaccharide from Dendrobium chrysotoxum Lindl against LPS-induced acute kidney injury mice

The structure and bioactivity of a novel polysaccharide from Dendrobium Chrysotoxum Lindl (DCP-1) were investigated. The crude polysaccharides of Dendrobium Chrysotoxum Lindl (DCP) were extracted by hot water extraction, and the protein was removed by enzymatic hydrolysis and Sevage. After purification, the chemical structure of polysaccharides was identified by infrared spectroscopy, methylation analysis and nuclear magnetic resonance spectroscopy. Then, a mouse model of acute kidney injury (AKI) was constructed using lipopolysaccharide (LPS), and pretreated with DCP. Structure characterization demonstrated that the number-average molecular weight and mass average molar mass of DCP-1 were 28.43 kDa and 15.00 kDa, respectively. DCP-1 mainly consisted of mannose (37.8 %) and glucose (55.6 %). The main linkage types of DCP-1 were contained 1,4-Linked Manp and 1,4-Linked Glcp. And DCP-1 was demonstrated to be an O-acetylglucomannan with β-ᴅ-configuration in pyranoid form. Besides, the bioactivity of DCP was further investigated. The results showed that DCP exhibited notable anti-inflammatory activity in LPS-induced AKI mice. After treated with DCP, the creatinine (CREA) and urea nitrogen (BUN) in serum were successfully down-regulated in AKI mice. DCP treatment prevented the characteristic morphological changes of LPS-induced renal tubular injury. The results showed that DCP treatment significantly reduced the concentration of oxidative damage indicators (MDA, SOD) and the expression of inflammatory indices (TNF-α, IL-6, MCP-1, COX-2). In general, the newly extracted polysaccharide DCP showed excellent nephroprotective effect, which enabled it to be an ideal natural medicine for kidney diseases therapy.

Synthesis of Novel (bis‐)1,5‐Disubstituted‐1H‐tetrazole‐Decorated Monomers and Their Respective Polymers via Thiol‐ene Polymerization

AbstractOver the years, nitrogen‐rich functional groups like tetrazole and its derivatives have received increasing interest in the chemistry of small molecules. There is a continuously growing interest in polymers decorated with nitrogen for potential biomedical applications because of their broad range of biological properties, such as being antibacterial, anticarcinogenic, and anti‐inflammatory. On this premise, a new synthesis route is reported for nitrogen‐decorated polymers via the combination of Ugi‐azide four‐multicomponent reaction (UA‐4MCR) and thiol‐ene polymerization. Accordingly, α,ω‐diene monomers decorated with (bis‐)1,5‐disubstituted‐1H‐tetrazoles (bis‐1,5‐DS‐Ts) are synthesized by using the UA‐4MCR. Subsequently, the light‐induced thiol‐ene polymerization facilitates the efficient synthesis of novel tetrazole‐decorated polymers with apparent number average molecular mass (Mn) up to 62 000 g mol−1, which are characterized for their chemical, thermal, and optical properties. The comprehensive characterization of the synthesized polymers is paving the way toward a wealth of opportunities, ranging from biomaterials to energy storage−relevant materials.

Isothermal crystallization kinetics in bulk of olefin-based multiblock copolymers

Isothermal crystallization kinetics of ethylene/1-octene (C2/C8) multiblock copolymers synthesized by chain shuttling technology is investigated. The samples are a reactor blend of segmented chains characterized by alternating crystalline and amorphous blocks with C8 content of 0.5 and 20 mol%, respectively, and statistical distribution of block number/chain and block length. The analysis is carried out after complete removal of a fraction (5–12 wt%), namely consisting of C8-rich blocks, through Kumagawa extraction with boiling diethyl ether. The resultant diethyl ether-insoluble fractions have similar average content of C8 units (≈13–14 mol%) and of crystalline blocks (≈23–27 wt%) but different molecular mass (the number average molecular mass Mn is ≈ 60–70 kDa for the samples 1,2 and ≈38 and ≈21 kDa for the samples 3 and 4, respectively). An additional sample with Mn ≈ 93 kDa, but a greater average content of C8 units (≈15 mol%) and a smaller content of crystalline blocks (15 wt%) is also analyzed. The crystallization half time of the samples increases with increase of Mn and, for each sample, its logarithm increases linearly with a decrease of the undercooling by a factor of -0.155/°C, for the samples 1–4 and −0.031/°C, for the sample 5. Using the classic kinetic crystallization model by Lauritzen and Hoffman, values of energy barrier constant due to contributions from primary nucleation KN and crystal growth KG are extracted. The KN contribution is esteemed to amount to ≈34% of the total barrier assuming regime II for the sample 5 and regime III (or I) for the samples 1–4, to ≈34% for the sample 5 and 67% for the samples 1–4, assuming regime II for all the samples. In all the cases, regardless of the assumed regimes, the KN values of the sample 5 are lower than those of the samples 1–4. As a final remark, the implications of crystallization kinetics on the solid-state morphology are also discussed, considering that transmission electron microscopy (TEM) images present a partially mesophase separated morphology for the samples 1,2, and 5 and a classic lamellar morphology for the samples 3 and 4.

Thermal Fractionation of Ethylene/1-Octene Multiblock Copolymers from Chain Shuttling Polymerization

Ethylene/1-octene statistical multiblock copolymers (OMBCs) consisting of the alternation of crystalline, hard blocks and amorphous, soft blocks, with ≈0.5 and 20 mol % of 1-octene units, respectively, are subjected to thermal fractionation resorting to successive self-nucleation and annealing (SSA). The study is extended to random copolymers (RCs) of high (44 kDa) and low (3.4 kDa) number average molecular mass Mn, mimicking in 1-octene content the crystalline hard blocks and to the OMBC fractions extracted in boiling n-hexane and cyclohexane through a suitable solution fractionation protocol. For all the samples, the melting endotherms are well resolved in a multiplicity of peaks corresponding to the melting of crystals of different thicknesses generated in the SSA protocol that reflect the distribution of the methylene sequence length (MSL) in between consecutive interruptions along the chains. It is shown that, regardless of molecular mass, the MSL distributions of the RC samples are shifted toward greater values than those of the OMBC samples, and that also the shapes of the distributions are different. Since the MSL distribution depends on the frequency and distribution of the defects along the chains, and the defects act as interruption points, the higher fraction of long crystallizable sequences in the RC samples suggests that whereas for the RC samples the interruptions are merely represented by the 1-octene units that are rejected outside the crystals, for the OMBCs, the interruption of the regular methylene sequences belonging to the crystalline hard blocks due to the amorphous soft blocks linked to them should also play a role. Indeed, due to the partial miscibility of the hard and soft blocks, the hard blocks of major length tend to crystallize in a confined environment. This prevents the formation of thicker crystals and induces decrease of the MSL values as well as changes in the shape of the MSL distributions (topological confinement). On the other hand, the hard blocks of shorter length tend to crystallize, crossing the hard block rich regions and causing melting point depression and consequent shift of the MSLs toward lower values with respect to RCs (diluent effect). It is shown that differences in the MSL distribution of OMBCs are the result of the interplay between topological confinement and diluent effect, which in turn reflects differences in the OMBC chain microstructure, that is, differences in the distribution of block length at the inter- and intra-chain level.

A critical evaluation of novel demulsifying agents based on acrylic terpolymers for Mexican heavy crude oils dehydration

• Random acrylic terpolymers as demulsifying agents for crude oil. • Trifunctional molecule with exceptional dehydrating and clarifying capacities. • Higher performance to dehydrate crude oils than commercial formulations. • Prediction of dehydrating efficiency as function of the crude oil properties. A novel kind of random acrylic terpolymers based on butyl acrylate (B), 2-(dimethylamino)ethyl acrylate (Ae), and 2-carboxyethyl acrylate (Ce) monomers was obtained by emulsion polymerization. Monomers’ weight ratios were varied, keeping in all cases a higher content of butyl acrylate (60, 70, 80, and 90 wt%) and controlling the number average molecular mass ( M ¯ n ) during polymerization. The random acrylic terpolymers were characterized by spectroscopic techniques; subsequently evaluated as demulsifier agents in three aged heavy crude oils of 7.55, 6.11, and 3.33 °API (apparent gravities), which form very stable water-in-oil (W/O) emulsions. The best performance for removing the emulsified water at 80 °C was obtained with terpolymers containing 90–80 wt% of the hydrophobic monomer B and small amounts of the hydrophilic monomers Ae and Ce (BAeCe-9551 and BAeCe-8111), being more efficient than two commercial demulsifiers (FDH-1 and F-46 TRETOLITE™). Moreover, the BAeCe-9551 terpolymer was evaluated in a fresh heavy crude oil of 20.2 °API at 60 °C — temperature of separation tanks —, showing better performance as breaker, coalescer, and clarifier than FDH-1. Finally, a quantitative structure–activity relationship (QSAR) analysis was carried out employing terpolymers’ molecular parameters and crude oils’ physicochemical parameters. Only one equation fulfilled all thresholds for Q F 1 2 , Q F 2 2 , Q F 3 2 , and r m 2 parameters, proving to be the most accurate to predict the water removal efficiency (WRE) of BAeCe-1 and BAeCe-2 series terpolymers when added to heavy crude oils. This correlation will allow selecting the best terpolymer for demulsifying a petroleum stream as a function of its physicochemical characteristics.

In‐depth material characterization of polyhydroxybutyrate from a forest biorefinery

AbstractLarge‐scale replacement of petroplastics with compostable plastics, like polyhydroxybutyrates (PHB) will contribute to elimination plastic pollution, decrease greenhouse gas emissions, and valorize local biomass resources. Lignocellulose hydrolysates have emerged as potentially sustainable carbon sources for PHB production. For industrial processing, it is necessary to know the polymer properties. Yet, most studies on PHB samples from lignocellulose report few material properties. PHB samples produced from a pilot scale hardwood holocellulose hydrolysate conversion process were characterized and compared with PHB from a sugar hydrolysate and a commercial PHB powder. PHB from hardwood holocellulose hydrolysate was found to be comparable with commercial PHB in all properties. Differential scanning calorimetry and thermal gravimetric analysis showed that all samples had similar thermal behavior, where the melting temperature was 176°C and the decomposition temperature was 293°C. From the melting enthalpy, all samples showed 63% crystallinity. Dynamic mechanical analysis showed a glass transition temperature at 5°C and a crystallization temperature of 57°C. Fourier transform infrared spectroscopy and nuclear magnetic resonance confirmed that the samples were homopolymers comprised of hydroxybutyrate units. The difference among the samples was the number average molecular mass, being lower for wood hydrolysate (246.4 kDa) than sugar hydrolysate (670.3 kDa).

Synthesis of Poly(azomethine) Containing Sulfonic Acid Unit Oxygen and Sulphur Bridged: Investigation of Its Thermal, Optical and Electrochemical Properties

In this study, a poly(azomethine) compound (SBP) containing sulfur and oxygen bridge was obtained from 4,4'-[thiobis(4,1-phenyleneoxy)]dibenzaldehyde (DBA) and 4,4'diamino-2,2'-biphenyl sulfonic acid from condensation reaction. Structural, optical, electrochemical and morphological analyzes of the obtained polymeric material were performed. Structural characterizations were performed from 1H-NMR and FT-IR spectra. Optical properties were determined in the UV-Vis spectrum and the optical band gap was calculated as 3.63 eV. Electrochemical properties were investigated by cyclic voltammetry (CV) and HOMO-LUMO and electrochemical band gap values were calculated. In addition, with the help of Gel Permeation Chromatography (GPC), the number average molecular mass was found to be 5050 Da. By thermogravimetric analysis (TGA), it was found that the thermal decomposition of SBP occurred in four steps and the maximum mass loss was 391 °C. The surface analysis of the obtained polymeric material was investigated with scanning electron microscope (SEM) and it was determined that the surface was rough.

Synthesis and characterization of poly(phthalazinone ether ketone ketone) copolymers with 4,4′-dihydroxybiphenyls

Meta-poly(phthalazinone ether ketone ketone) copolymers with 4,4′-dihydroxybiphenyls (meta-PPBEKK) was synthesized with 4,4′-dihydroxybiphenyls (BP), 1,3-bis(4-fluorobenzoyl)benzene (meta-DFKK) and 4-(4-hydroxyphenyl)-2,3-diazaphthalene-1-one (DHPZ). The copolymers are high-temperature resistant and have good solubility in many solvents. With increasing molar ratio of BP to meta-DFKK from 0 to 0.2, the addition of BP improves number-average molecular masses, intrinsic viscosity, mechanical properties and fluidity of meta-PPBEKKs. When the molar ratio of BP to meta-DFKK is 0.2, the intrinsic viscosity reaches 1.14 dL g−1, the number-average molecular mass reaches 44700 g mol−1, the maximum thermal elongation ratio reaches 14 with strength of 127.1 MPa and Young’s modulus of 2.4 GPa. With increasing molar ratio of BP to meta-DFKK from 0 to 0.2, meta-PPBEKKs have improved comprehensive properties, and make sense in many fields.

Properties of Polyhexamethylene Guanidine (PHMG) Associated with Fatal Lung Injury in Korea.

The use of humidifier disinfectant (HD) has been determined to be associated with lung injuries (HDLI) in Korea. Although HD brands containing polyhexamethylene guanidine (PHMG) oligomers have been found to cause more HDLI compared to brands containing other disinfectants, the physicochemical properties of PHMG have been poorly defined. We aimed to quantify the PHMG dissolved in HD brands, characterize the number-average (Mn) and weight-average (Mw) molecular masses, and identify the polymerization degree of PHMG. Analysis of the PHMG oligomers was performed using a matrix-assisted laser desorption/ionization time-of-flight mass spectrometer (MALDI-TOF MS) operated in positive-ion reflectron mode. Eight brands of HD containing PHMG were identified. The PHMG concentrations in these brands ranged from 160 to 37,200 ppm (mean = 3100.9 ppm). Concentration was a significant variable among and within HD brands. The degree of PHMG oligomerization fell within the range of two to four. The averages of Mn and Mw were 517.2 g/mol (range: 422–613 g/mol) and 537.3 g/mol (range: 441.0–678.0 g/mol), respectively. Based on the average molecular weight and the degree of polymerization, the PHMG examined here could be regarded as oligomers, which may be associated with the highest proportion of HDLI being caused by PHMG.

Preparation, statistical optimization and characterization of poly(3‐hydroxybutyrate) fermented by Cupriavidus necator utilizing various hydrolysates of alligator weed (Alternanthera philoxeroides) as a sole carbon source

Alligator weed (Alternanthera philoxeroides) is a stoloniferous, amphibious and perennial herb which has invaded many parts of the world and led to serious environmental and ecological problems. In order to exploit cheap carbon source for poly(3-hydroxybutyrate) (PHB) production, alligator weed hydrolysates were prepared by acid and enzyme treatment and used for PHB production via Cupriavidus necator. The bacterium utilized alligator weed enzymatic hydrolysate and produced the PHB concentration of 3.8 ± 0.2 g/L at the conditions of pH 7.0, 27.5°C, 1.5 g/L of nitrogen source, and 25 g/L of carbon source, this exceeded the value of 2.1 ± 0.1 g/L from acid hydrolysate media at the same conditions. In order to obtain the optimum conditions of PHB production, response surface methodology was employed which improved PHB content. The optimum conditions for PHB production are as follows: carbon source, 34 g/L; nitrogen source, 2 g/L; pH, 7; temperature, 28°C. After 72 hr of incubation, the bacterium produced 8.5 g/L of dry cell weight and 4.8 g/L of PHB. The PHB was subjected to Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), and Molecular weight analysis and found the melting temperature, number average molecular mass, and polydispersity were 168.20°C, 185 kDa, and 2.1, respectively.

Structural Features and Rheological Properties of a Sulfated Xylogalactan-Rich Fraction Isolated from Tunisian Red Seaweed Jania adhaerens

A novel sulfated xylogalactan-rich fraction (JSP for J. adhaerens Sulfated Polysaccharide) was extracted from the red Tunisian seaweed Jania adhaerens. JSP was purified using an alcoholic precipitation process and characterized by Attenuated Total Reflectance-Fourier-transform infrared spectroscopy (ATR-FTIR), high-pressure size exclusion chromatography (HPSEC) with a multi-angle laser light scattering (MALLS), gas chromatography coupled to mass spectrometry (GC-MS) and nuclear magnetic resonance spectroscopy (NMR, 1D and 2D). JSP was then evaluated regarding its physicochemical and rheological properties. Results showed that JSP was mainly composed of an agar-like xylogalactan sharing the general characteristics of corallinans. The structure of JSP was mainly composed of agaran disaccharidic repeating units (→3)-β-d-Galp-(1,4)-α-l-Galp-(1→)n and (→3)-β-d-Galp-(1,4)-3,6-α-l-AnGalp-(1→)n, mainly substituted on O-6 of (1,3)-β-d-Galp residues by β-xylosyl side chains, and less with sulfate or methoxy groups. (1,4)-α-l-Galp residues were also substituted by methoxy and/or sulfate groups in the O-2 and O-3 positions. Mass-average and number-average molecular masses (Mw) and (Mn), intrinsic viscosity ([η]) and hydrodynamic radius (Rh) for JSP were, respectively, 8.0 × 105 g/mol, 1.0 × 105 g/mol, 76 mL/g and 16.8 nm, showing a flexible random coil conformation in solution. The critical overlap concentration C* of JSP was evaluated at 7.5 g/L using the Williamson model. In the semi-diluted regime, JSP solutions displayed a shear-thinning behavior with a great viscoelasticity character influenced by temperature and monovalent salts. The flow characteristics of JSP were described by the Ostwald model.

Модификация матрицы арабиногалактана в процессе формирования металлополимерных нанобиокомпозитов

Transformation of arabinogalactan matrix in the process formation of metal containing nanobiocomposites has been investigated. Molar mass characteristics of arabinogalactan in content of metal polymer nanobiocomposities were determined by method of Size-Exclusion Chromatography (SEC). It was shown that change of polydispersity of the arabinogalactan is occuring due to of oxidation-reduction with noble metal ions and alkaline destruction. It was established that at the alkaline depolymerisation occurred in the synthesis of nanocomposities number-average molecular mass of arabinogalactan significantly is decreased.

Separation and Identification of Oligomeric-Hindered Amine Light Stabilizer Uvasorb HA 88 by High-performance Liquid Chromatography (HPLC) Coupled With Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALSI-TOF-MS)

Uvasorb HA 88 is widely used as a light stabilizer to prevent plastic polymer degradation. Its high molecular weight and oligomeric characters provide challenge for quality control. In this study, high-performance liquid chromatography (HPLC) coupled with electrospray ionization time of flight mass spectrometry (ESI-TOF MS) was applied for separation and detection of Uvasorb HA 88. The synthesis scheme was deduced and confirmed by the characterization of Uvasorb HA 88 products from different batches. Direct matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) was employed for the detailed characterization of chemical composition of Uvasorb HA 88. Furthermore, a reliable reversed-phase high-performance liquid chromatography (RP-HPLC) coupled with MALDI-TOF MS method was established and the weight-average and number-average molecular masses were calculated. The results revealed that six oligomers with repeat unit numbers from 1 to 4 were present in Uvasorb HA 88. A molecular weight of up to 6808 g mol−1 was detected and two new series of oligomers were reported for the first time. Different series of oligomers and positional isomers were observed in Uvasorb HA 88. This work provides a suitable method to evaluate the technical grade of Uvasorb HA 88 as well as comprehensive characterization of complex oligomeric hindered amine light stabilizers.

Quantitative Structure-Activity Relationship (QSAR) analysis of functionalized triblock copolymers with applications as dehydrating agents of crude oil

QSAR analysis was applied to obtain the water removal efficiency (WRE) values of triblock copolymers functionalized with tertiary amines, employed as demulsifier agents of crude oil. Taking into account the evaluation of F- and G-series reported by Zamora et al., the H-series was synthesized based on a triblock copolymer of 1920 g mol−1, and evaluated in CM1 and CM2 crude oils (7.5 and 18.7 °API). In addition, quantum and QSAR parameters, physicochemical properties of crude oil were included in the QSAR analysis. 66 WRE values were considered in the training set. Q2 value was established to weigh up an equation as acceptable, achieving eight equations, T1 – T8, for the training set. About external validation, F-, G- and H-series were assessed in CM3 heavy crude oil (16.9 °API), considering an overall of 33 WRE values for the validation. For the external validation, the coefficient of the prediction set (R2EXT), the predictive squared correlation coefficient (Q2Fn), the metric value (r2m), the concordance correlation coefficient (CCC), and the regression line slopes (k and k’) criteria were obtained. Only two equations, T1 and T8, complied with threshold established in the validation criteria. About r2m criterion, T8 equation gave a better correlation, 0.62, than that of T1 equation, 0.58. However, both equations could be optimal to calculate the water removal efficiency. Regarding physicochemical parameters of crude oil, number average molecular mass and run-off temperature were the unique parameters showing a clear effect over the calculated water removal efficiency.

The synthesis, characterization and effect of molar mass distribution on solid-state degradation kinetics of oligo(orcinol)

In this study, the oxidative polymerization of orcinol monohydrate using different oxidants such as NaOCl, H2O2, and air was investigated. Polymerization studies were carried out between 50 and 90 °C. The optimum reaction conditions of the polymerization were also established. NaOCl was found to be the most active oxidant. The characterization of oligo(orcinol) was conducted by using FT-IR, 1H-NMR and 13C-NMR, TGA, size exclusion chromatography (SEC) and solubility techniques. At the optimum reaction conditions, the conversion to oligomer of orcinol was found to be 62% (for NaOCl oxidant), 42% (for H2O2 oxidant), and 21% (for air oxidant). According to the SEC analysis, the number-average molecular mass (Mn), mass-average molecular mass (Mw) and polydispersity index (PDI) values of oligo(orcinol) were determined to be 2260, 2540 g mol−1, and 1.12, using NaOCl, and 2170, 2470 g mol−1, and 1.14, using H2O2 and 1500, 1770 g mol−1, and 1.18, using air, respectively. In addition, the relationship between molar mass distributions and activation energies of thermal degradation processes of oligo(orcinol) was investigated by using TG analysis. For this purpose, the methods based on multiple heating rates such as Flynn–Wall–Ozawa [FWO], Tang, and Kissinger–Akahira–Sunose [KAS] were used. The activation energy related to the solid-state decomposition of oligo(orcinol) synthesized with NaOCl oxidant was calculated to be 79.02 kJ mol−1 by KAS method, 78.74 kJ mol−1 by Tang method and 81.78 kJ mol−1 by FWO method in the range of 0.05 < α < 0.95. The results obtained show that activation energy increased with an increase in molar mass.

3D Printing of Poly(propylene fumarate) Oligomers: Evaluation of Resin Viscosity, Printing Characteristics and Mechanical Properties.

Complex three-dimensional (3D) pore geometries, useful for tissue engineering scaffolds, can be fabricated via photo-crosslinking of resorbable poly(propylene fumarate) (PPF) resins using stereolithography (SLA) and/or continuous digital light processing (cDLP) methods. Physico-chemical parameters inherent to 3D printable resin design, include viscosity, polymer concentration, degree of polymerization, and resin printing temperature. We report here on our study of these parameters and their influence the cDLP 3D printing process and the resulting mechanical properties. A series of PPF oligomers were synthesized by the ring-opening copolymerization (ROCOP) of maleic anhydride and propylene oxide followed by a base-catalyzed isomerization. The resin viscosities were measured as a function of number-average molecular mass ([Formula: see text]) of the PPF oligomers (1.1, 1.7 and 2.0 kDa), concentrations of PPF in the reactive diluent diethyl fumarate (DEF) (50 and 75 wt %) and resin temperature (25 to 55 °C). The zero-shear viscosity (η0) of the resins was found to be temperature-dependent and follow a linear Arrhenius relationship. Tensile tests demonstrated mechanical properties within the range of trabecular bone, with the ultimate strength at break above 15 MPa and elastic moduli between 178 and 199 MPa.

Synthesis, Characterization and Photoluminescence Studies of Organic Copolymer Resin

The present paper reports synthesis of copolymer resin and its metal complexes. Copolymer resins (8-HQ5-SAHMDAF-II) have been obtained using condensation method from 8-hydroxyquinoline-5-sulfonic acid, hexamethylenediamine and formaldehyde monomer by using 2M HCl as catalyst with efficient refluxed at about 124 0C to 126 0C temp up to five hrs. The copolymer metal complexes have been integrated utilizing the combined copolymers as ligand with few progress metal particles, for example, Cu2+, Ni 2+ and Zn2+ ions in 2:1 molar proportion. Reactions have been completed with an efficient refluxed about 60°C temp for 3h. The photoluminescence properties of recently integrated copolymer metal complex samples were recorded on RF-501 (PC) S CE (LVD) MODEL. The point of this present investigation is to deliver the cooperative assistance among design and photoluminescence through new and critical commitments from dynamic specialists in the field. The composition of (8-HQ5-SAHMDAF) organic copolymer has been resolved based on essential examination. Number average molecular mass of this copolymer was dictated by non-aqueous conductometric titration method. The copolymer (8-HQ5-SAHMDAF-II) was characterized by FT-IR, 1H-NMR Spectroscopy.

Prospects for Using Styrene-Isobutylene-Styrene (SIBS) Triblock Copolymer as a Cusp Material for Leaflet Heart Valve Prostheses: Evaluation of Physicochemical and Mechanical Properties

Search for promising polymer materials as a base for cusps of leaflet heart valve prostheses is a topical problem from the viewpoint of limited durability of fixed biological material. For this purpose, styrene-isobutylene-styrene (SIBS) triblock copolymer was prepared by controlled cationic polymerization. The synthesized SIBS is characterized by the number-average molecular mass Mn = 33 000 and narrow monodisperse molecular-mass distribution (Mw/Mn = 1.3). The ultimate strength of the polymer film was lower than that of xenopericard and ePTFE in the longitudinal direction by a factor of 3.30 and 6.36, respectively (p < 0.05); it was lower than that of ePTFE in the transverse direction by a factor of 4.58 (p < 0.05) and did not differ significantly (p = 0.65) from that of xenopericard in the transverse direction. The relative elongation and Young’s modulus of the SIBS film exceeded those of ePTFE and xenopericard in the longitudinal direction by a factor of 3.00 and 5.68 and in the transverse direction by a factor of 6.50 and 3.86, respectively (p < 0.05). The contact angle for different sides of the SIBS film was 101.6° ± 2.9°/104.4° ± 0.9°. According to the data of atomic force microscopy, the height difference on the SIBS surface usually did not exceed 1 µm, with separate pits of 20–40 µm size. The results of studying the physical properties of the surface and the mechanical properties determining the primary biocompatibility factors in comparison with control materials show that SIBS polymers are promising for making leaflet heart valve prostheses.

Modeling the molecular weight and number average molecular masses during the photo-thermal oxidation of polypropylene using neural networks

This work investigates the potential of artificial neural network (ANN) model to predict the molecular weight (M W ) and number average molecular masses (Mn) during the photo-thermal oxidation of polypropylene (pp). A set of 116 data points were used to test the neural network, 80%, 10%, and 10% of the database were used, or the training, the validation, and the test of the model. The optimal topology of ANN model obtained with the architecture of (3 inputs, 23 hidden and 2 output neurons). Statistical analyses of neural network model show good agreement with experimental data (a coefficient of correlation equal to 0.9864 and 0.9688, and a root mean square error equal to 11.1250 kg/mol and 3.5284 kg/mol for the predicted molecular weight and number average molecular masses respectively), considering, a three layer feed-forward backpropagation neural network with BFGS quasi-Newton (trainbfg) training algorithm, a hyperbolic tangent sigmoid and logarithmic sigmoid transfer function at the hidden and the output layer respectively. The comparison between the experimental and calculated results show that the ANN model is able of predicted the molecular weight and number average molecular masses during the photo-thermal oxidation of polypropylene.