Synthesis, characterization and kinetics of hydrophobically associating polyacrylamide

e-Polymers ◽  
2007 ◽  
Vol 7 (1) ◽  
Author(s):  
Lu Hongsheng ◽  
Feng Yujun
Keyword(s):  
Molecular Weight ◽  
Particle Size ◽  
Strong Dependence ◽  
Weight Fraction ◽  
Initiator Concentration ◽  
H Nmr ◽  
Inverse Microemulsion ◽  
Ft Ir ◽  
Chain Transfer Reaction ◽  
The Difference

AbstractHAPAM was successfully prepared in inverse microemulsion. 1H-NMR, FT-IR, DSC and TG results show that the copolymerization of acrylamide (AM) with DM16 was successful. However, the ratio of AM to DM16 is not calculated exactly due to the low percentage of hydrophobic monomer in polymer. Therein, we only proved the success of the incorporation of DM16 onto polyacrylamide backbone. According to our experiment, the conversions of monomers and molecular weight have a strong dependence on initiator concentration and aqueous phase weight fraction. But it was not completely in accordance with literature. The difference may be ascribed to the major existence of locus of DM16 (at the interface of oil/water or in droplet). Compared with literature, the influence of initiator concentration on particle size was slight due to the high surfactant weight fraction, seeming to appear independent of initiator concentration. When the surfactant weight fraction reaches a certain degree, it did not affect the conversion. For the particle size and molecular weight, it was other way around, suggesting that there was an intense chain transfer reaction to the emulsifier. In this work, we could not calculate the average number of free radical per particle n, because the part of the surfactant in excess recombines to form small micelle and the DM16 may continuously transfer from micelle to another micelle, resulting in difficulty to estimate precisely the number of the particles. This was also reflected in the difference of kinetics between our system and literature. Finally, the occurrence of nucleation at high conversion was proved indirectly.

Carborane-containing bismaleimide resins with excellent heat resistance and dimensional stability

2020 ◽  
pp. 095400832094893
Author(s):  
Yuane Wu ◽  
Gong Chen ◽  
Longfei Gao ◽  
Wei Zhang ◽  
Song Li
Keyword(s):  
Heat Resistance ◽  
Thermal Property ◽  
Dimensional Stability ◽  
Coefficient Of Thermal Expansion ◽  
Weight Fraction ◽  
Curing Temperature ◽  
Bismaleimide Resin ◽  
H Nmr ◽  
Ft Ir ◽  
Bismaleimide Resins

Novel carborane-containing bismaleimides with excellent heat resistance and dimensional stability for advanced composites are presented. First, a new kind of carborane-containing mono-maleimido-terminated monomer 1-(4-tolyl)-2-(4-maleimido phenyl)- o-carborane (CB-MI) was synthesized and characterized by FT-IR and 1H-NMR. Then, it was used as a modifier for bismaleimide resin 4,4’-bismaleimidodiphenylmethane (BDM) with different weight fraction of CB-MI. The curing behavior and thermal property of the CB-MI/BDM resin systems were studied and presented here. Results displayed that a wide processing window and low curing temperature provided a good processability for the CB-MI/BDM resin system. Due to the effect of carborane groups, the char yield at 600°C of the cured resin systems tended to be increased with the addition of CB-MI. Moreover, the coefficient of thermal expansion of the resin was found to be reduced with the increase of CB-MI, indicative of a remarkable dimensional stability. This study might open up great opportunities for the preparation and design of various novel bismaleimides in a simple and feasible way and the resins with good thermal property and processability at the same time.

A New Green Process for Synthesising High Quality PLLA Materials

2013 ◽  
Vol 750-752 ◽  
pp. 1377-1380 ◽  
Author(s):  
Hui Li Shao ◽  
Xian Jue Zhou ◽  
Xue Chao Hu
Keyword(s):  
Molecular Weight ◽  
Ring Opening ◽  
Average Molecular Weight ◽  
Gel Permeation Chromatography ◽  
Ring Opening Polymerization ◽  
Green Process ◽  
Weight Average Molecular Weight ◽  
H Nmr ◽  
Ft Ir ◽  
C Nmr

Synthesis of Poly(L-lactide) (PLLA) by the ring-opening polymerization (ROP) of L-lactides in supercritical carbon dioxide (SC-CO2) with co-solvent were studied. Effects of kinds of co-solvent on the molecular weight (MW) and the molecular weight distribution (MWD) of the resultant polymers were investigated by the gel permeation chromatography (GPC). The resultant polymers were also characterized with1H NMR,13C NMR and FT-IR. It was found that PLLA with high purity and almost without racemization could be obtained by this technology and the acetone is the best co-solvent for this kind of polymerization. By using stannous octoate as initiator and acetone as co-solvent, PLLA having a weight-average molecular weight (Mw) near to 9×104and polydispersity index (PDI) of 1.7 was successfully synthesized.

scholarly journals Synthesis, Characterization and Copolymerization of N-(phenylamino)maleimide with MMA

2007 ◽  
Vol 4 (2) ◽  
pp. 265-271
Author(s):  
B. L. Hiran ◽  
S. N. Paliwal ◽  
Jyoti Choudhary ◽  
P. R. Choudhary
Keyword(s):  
Thermal Stability ◽  
Molecular Weight ◽  
Density Measurement ◽  
Gel Permeation Chromatography ◽  
Radical Copolymerization ◽  
Free Radical Copolymerization ◽  
H Nmr ◽  
Gel Permeation ◽  
Ft Ir ◽  
Thermal Stability Of

The free radical copolymerization of N-(phenylamino)maleimide (N-PAMI) was carried. The copolymerization with methyl methacrylate (MMA) was performed at 65°C with AIBN as the initiator in THF solvent. Resulting copolymer was characterized by density measurement, intrinsic viscosity, solubility, FT-IR &1H NMR spectroscopy. Effect of the solvent and time on copolymer yield was also investigated. The molecular weight of copolymer was determined by gel permeation chromatography (GPC). The thermal stability of copolymer was determined by Thermogravimetric analysis (TGA).

scholarly journals Preperation of nanochitosan from radiation degraded oligochitosan for shelf life extension of strawberry

2021 ◽  
Vol 7 (3) ◽  
pp. 34-41
Author(s):  
Hoanh Phong Nguyen Trong ◽  
Xuan Cuong Le ◽  
Duy Hang Nguyen ◽  
Tan Man Nguyen ◽  
Minh Hiep Nguyen ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Molecular Weight ◽  
Particle Size ◽  
Gamma Ray ◽  
Spherical Shape ◽  
Life Extension ◽  
Cross Linking ◽  
Coating Method ◽  
Ft Ir ◽  
Scanning Electron

Oligochitosans (OCT) were prepared from chitosan (CTS) by gamma irradiationtechnique. The parameters affecting to the chitosan degradation were studied. And then, OCT nanoparticles wereformed using the method of tripolyphosphate (TPP) cross-linking. Effect of concentration and molecular weight of OCT, concentration of TPP on particle size of the formed OCT nanoparticles were also studied. The formation of OCT nanoparticles was verified by Fourier transform infrared (FT-IR) spectrometer and differential scanning calorimeter (DSC), the morphology was observed using scanning electron microscope (SEM), and the characteristics (particle size and zeta potential) of OCT nanoparticles were also studied. The effect of OCT nanoparticles on strawberry presevation was carried out using the coating method. Results showed that an increase in radiation dose resulted in a decrease of chitosan molecular weight. The OCT with molecular weight of approximately 7.7 kDa was obtained by the synergistic effect of hydrogen peroxide (5 %, v/v) and gamma ray at dose of 30 kGy. The smaller OCT nanoparticles was obtained with a lower molecular weight of OCT. The results of FTIR, DSC indicated the success in the formation of OCT nanoparticles with the particle size approximately 129.9 nm, with the spherical shape. The application of OCT nanoparticles on strawberry has prolonged the preservation times approximately 2.5 times higher comp

scholarly journals Fractionation of lignin produced from the Earleaf Acacia tree by sequential industrial organic solvents

2021 ◽  
Vol 24 (1) ◽  
pp. 1835-1841
Author(s):  
Thong Hoang Le ◽  
Khanh B. Vu ◽  
Quynh-Thy Song Nguyen ◽  
Phat Van Huynh ◽  
Khanh-Ly T. Huynh ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Organic Solvent ◽  
Ethyl Acetate ◽  
Organic Solvents ◽  
Weight Fraction ◽  
Ft Ir ◽  
Catalytic Applications ◽  
Light Medium ◽  
Acacia Tree ◽  
Different Molecular Weight

Introduction: Understanding the fractions of lignin is important for further conversion of lignin into valuable products. Herein, the “home-made” lignin from Earleaf Acacia tree was extracted by sequential industrial organic solvent and characterized each fraction to reveal its properties for further catalytic applications. Methods: In this work, lignin was prepared from the Earleaf Acacia tree using the soda method. Then, the prepared lignin was fractionated by sequential solvents of ethyl acetate, ethanol, methanol, and acetone. Each lignin fractions were characterized by FT-IR and GPC. Results: The FT-IR results confirmed the soda method can produce lignin from woodchips. The fractionation of lignin separated the lignin mixture into different molecular weight fraction from light – medium into heavy compounds. Conclusion: Lignin was produced from woodchips using the soda method successfully. The fractionation using the sequential organic solvents showed the separation of different molecular weight of lignin, which allow to apply for the further conversion into useful products.

scholarly journals Preparation of Higher Molecular Weight Poly (L-lactic Acid) by Chain Extension

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Chenguang Liu ◽  
Yuliang Jia ◽  
Aihua He
Keyword(s):  
Molecular Weight ◽  
Lactic Acid ◽  
Average Molecular Weight ◽  
Hexamethylene Diisocyanate ◽  
Chain Extension ◽  
Poly Lactic Acid ◽  
Weight Changes ◽  
H Nmr ◽  
Left Handed ◽  
Ft Ir

High molecular weight poly (lactic acid) (PLA) was obtained by chain extending with hexamethylene diisocyanate (HDI). The influences of the amount of chain extender, reaction time, and molecular weight changes of prepolymers on the poly(lactic acid) were investigated. PLA prepolymer with a viscosity, average molecular weight (Mη) of 2 × 104 g/mol was synthesized froml-lactide using stannous octoate as the catalyst. After 20 min of chain extension at 175°C, the resulting polymer hadMwof 20.3 × 104 g/mol andMnof 10.5 × 104 g/mol. Both FT-IR and1H-NMR verified that the structure of PLA did not change either before chain extending or after. The optically active characterized that the chain extending-product was left handed. DSC and XRD results showed that both theTgand the crystallinity of PLA were lowered by chain-extension reaction. The crystalline transformation happened in PLA after chain extending, crystallineα′form toαform.

The interaction between tea polyphenols and rice starch during gelatinization

2011 ◽  
Vol 17 (6) ◽  
pp. 569-577 ◽  
Author(s):  
Yue Wu ◽  
Qinlu Lin ◽  
Zhengxing Chen ◽  
HuaXi Xiao
Keyword(s):  
Interaction Strength ◽  
Tea Polyphenols ◽  
Coupling Constants ◽  
Rice Starch ◽  
Strong Interactions ◽  
H Nmr ◽  
Two Samples ◽  
Ft Ir ◽  
The Difference ◽  
Paste Viscosity

The interaction between tea polyphenols (TPLs) and rice starch (RS) during gelatinization has been studied. In the RVA analysis, TPLs-fortified RS exhibited no clearly defined peak viscosity and hot paste viscosity. After excluding other factors, irregular viscosity changes were attributed to the strong interactions between RS and TPLs during pasting/gelatinization. Subsequently, the coupling constants of samples A (the gelatinized sample of the blend of 16% TPLs and RS) and B (the blend of 16% TPLs and gelatinized RS sample) in 1H-NMR measurements were found to be the difference. Sample A had two coupling constants, 26h JHH = 82.08, 100.77 Hz and 6h JHH = 35.57 Hz, whereas Sample B had one larger coupling constant, 9h JHH = 140.24 Hz. This implied that these two samples differed in H–H interaction and interaction strength of sample A may be stronger than that of sample B. More important is, sample A had clearly broadened O–H stretching and frequency red-shifts of C–O–H bending as compared with sample B in quantitative FT–IR analysis. The overall results indicate that TPLs and RS can have hydrogen bonding interaction during gelatinization.

Spectroscopic and Molecular Weight Studies of Polytoluidines

1989 ◽  
Vol 173 ◽  
Author(s):  
Y. Wei ◽  
K. F. Hsueh ◽  
S. Nagy ◽  
A. Ray ◽  
A. G. MacDiarmid ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Quantitative Estimation ◽  
Gel Permeation Chromatography ◽  
Weight Fraction ◽  
Oxidation States ◽  
H Nmr ◽  
Elution Pattern ◽  
Repeat Units ◽  
Base Form ◽  
Field Desorption Mass Spectrometry

ABSTRACTPoly(o-toluidine) and poly(m-toluidine) in base form have been characterized by infrared and lH NMR spectroscopy. Assignments of the proton NMR signals have been facilitated by the use of model compounds. The distinction between benzenoid and quinoid methyl resonances in the NMR permits a semi-quantitative estimation of the oxidation states of the polytoluidines. Infrared studies are consistent with a polyaniline-type backbone having pendant methyl groups. Field desorption mass spectrometry (FD-MS) was employed for estimation of the molecular weight of poly(o-toluidine). Gel-permeation chromatography of the same sample showed a bimodal elution pattern, suggesting that the FD-MS technique detects only the lower molecular weight fraction of the polymer. Despite this inherent limitation, FD-MS yields the interesting information that the polymer contains chains of both odd and even numbers of repeat units, necessitating the coexistence of different oxidation states in the base form of the polymer.

scholarly journals Fast and Convenient Synthesis of Amine-Terminated Polylactide as a Macroinitiator forω-Benzyloxycarbonyl-L-Lysine-N-Carboxyanhydrides

2011 ◽  
Vol 2011 ◽  
pp. 1-7 ◽  
Author(s):  
Mingjie Ju ◽  
Feirong Gong ◽  
Shujun Cheng ◽  
Yun Gao
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Ring Opening ◽  
Ring Opening Polymerization ◽  
Low Molecular Weight ◽  
Amine Group ◽  
H Nmr ◽  
Convenient Synthesis ◽  
Ft Ir ◽  
Chain Lengths

Amine-terminated poly (L-lactide) (NH2-PLLA) with various chain lengths were successfully synthesized by sequential tert-butyl-N-(3-hydroxypropyl) carbamate initiated bulk ring-opening polymerization (ROP) of L-lactide (L-LA) in the presence of Stannous(II) 2-ethylhexanoate (Sn(Oct)2) and deprotection of theN-tert-butoxycarbonyl (Boc) group at the end of the polymer chain. The polymers obtained were characterized by FT-IR,1H NMR, and GPC method. NH2-PLLA thus prepared was used to initiate the polymerization of ω-benzyloxycarbonyl-L-lysine-N-carboxyanhydride (Lys (Z)-NCA), and the result confirmed the high nucleophilicity of the terminal amine group. This method was not only suitable for the preparation of low molecular weight NH2-PLLA, but also quite efficient in the synthesis of high molecular weight samples.

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