Simulation and Analysis of Propylene Coordination Polymerization Process Based on Aspen (polymer) plus

2020 ◽  
Vol 42 (1) ◽  
pp. 62-62
Author(s):  
Jinjin Wang Jinjin Wang ◽  
Wangbin Chen Wangbin Chen ◽  
Manlin Zhang Manlin Zhang ◽  
Bin Pan Bin Pan ◽  
Xiaorong Wang Xiaorong Wang ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Performance Index ◽  
Average Molecular Weight ◽  
Degree Of Polymerization ◽  
Average Degree ◽  
Polymerization Process ◽  
Polymerization Degree ◽  
Coordination Polymerization ◽  
Actual Production ◽  
Coordination Process

Based on the industrial conditions of coordination polymerization of polypropylene, Polymer plus was used to simulate and analyze the coordination process of propylene. The effects of the amount of propane, main catalyst (TiCl4), chain transfer agent (hydrogen), shielding gas (nitrogen), and monomer (propylene) on the number average degree of polymerization (DPN), the weight average degree of polymerization (DPW), the number average molecular weight (MWN), the weight average molecular weight (MWW), the polydispersity index (PDI), and the throughput of polypropylene were explored to guide actual production in this paper. Through analysis, the polymerization degree and molecular weight of polypropylene could be adjusted by hydrogen in actual production. The monomer (propylene) should be purified as much as possible to reduce the feed amount of propane. The increase of the propylene contributed to the molecular weight and polymerization degree of the product. The increase in the nitrogen feed amount had no effect on the product performance index. The feed amount of nitrogen could be adjusted as needed according to the actual equipment specifications. The catalyst has the greatest influence on the comprehensive performance index of the product, thus the amount of main catalyst TiCl4 must be strictly controlled.

METAL OXIDE TRIALKYLSILYLOXIDE POLYMERS (POLYTRIALKYLSILOXANOMETALLOXANES): PART I. TITANIUM OXIDE TRIMETHYLSILYLOXIDE POLYMERS

1963 ◽  
Vol 41 (3) ◽  
pp. 629-635 ◽  
Author(s):  
D. C. Bradley ◽  
C. Prevedorou-Demas
Keyword(s):  
Molecular Weight ◽  
Metal Oxide ◽  
Titanium Oxide ◽  
Degree Of Polymerization ◽  
Average Degree ◽  
Degree Of Hydrolysis ◽  
Controlled Conditions

Tetrakis-(trimethylsilyloxy)-titanium Ti(OSiMe3)4 has been hydrolyzed under controlled conditions in dioxane. The initial products of hydrolysis undergo facile disproportionation, e.g. 3Ti2O(OSiMe3)6 → 4Ti(OSiMe3)4 + polymeric Ti2O3(OSiMe3)2. Molecular weight determinations were made on the titanium oxide trimethylsilyloxide polymers (polytrimethylsiloxanotitanoxanes) obtained by thermal disproportionation. Structures have been suggested for the polymers on the basis of the variation of number-average degree of polymerization with the degree of hydrolysis.

Exploring the formaldehyde reactivity of tannins with different molecular weight distributions: bayberry tannins and larch tannins

Holzforschung ◽  
2020 ◽  
Vol 74 (7) ◽  
pp. 673-682 ◽  
Author(s):  
Tao Yang ◽  
Mengqi Dong ◽  
Juqing Cui ◽  
Lu Gan ◽  
Shuguang Han
Keyword(s):  
Molecular Weight ◽  
High Performance ◽  
Average Molecular Weight ◽  
Degree Of Polymerization ◽  
Standard Curve ◽  
Molecular Weight Distributions ◽  
Weight Distributions ◽  
Curve Method ◽  
Standard Curve Method ◽  
Tannin Degradation

AbstractIn recent years, tannin degradation has been used to obtain tannin materials with an optimal molecular weight distribution (MWD) for synthesizing tannin-formaldehyde (TF) resin with high performance, but the optimal MWD of tannins is still unknown. The excellent formaldehyde reactivity of tannins is the basis for the synthesis of high-performance TF resin. Based on the formaldehyde reactivity of tannins, bayberry tannins and larch tannins were used to explore the optimal MWD of tannins for TF resin synthesis. Progressive solvent precipitation (PSP) was used to obtain tannin fractions with different MWDs. The formaldehyde reactivity of tannins was determined using the modified Stiansy method combined with the standard curve method (GB/T 17657-2013). The bayberry tannin fraction [weight-average molecular weight (Mw) of acetylated tannin: 4115, mean degree of polymerization (mDP): 6.64] and the larch tannin fraction (Mw of acetylated tannin: 3906, mDP: 5.84) had the best formaldehyde reactivity. Furthermore, significant differences in the formaldehyde reactivity of condensed tannins (CTs) with different MWDs were observed. The obtained results can be used to purposefully degrade tannins to achieve an optimal MWD, which is beneficial for the production of TF adhesives with high performance.

Step-growth polymerization—basics and development of new materials

2004 ◽  
Author(s):  
Zhiqun He ◽  
Eric A . Whale
Keyword(s):  
Molecular Weight ◽  
Degree Of Polymerization ◽  
Average Degree ◽  
Chain Growth ◽  
Side Reactions ◽  
Growth Processes ◽  
Molecular Weights ◽  
Reactive Groups ◽  
Step Growth ◽  
Step Growth Polymerization

Step-growth polymerization is often referred to as condensation polymerization, since often—but by no means always—small molecules such as water are released during the formation of the polymer chains. There are a number of differences in the way polymerization occurs in step-growth polymerization compared to chain-growth processes, and these have marked practical implications. The most obvious difference is that, as the name implies, the polymer chain grows in a step-wise fashion; the initial stage of the reaction involves the conversion of monomers to dimers and from these other lower molecular weight oligomers. It is only as the reaction nears completion that significant quantities of higher molecular weight material can be formed. Thus, in order to obtain effective molecular weights, the reaction must proceed almost to completion, indeed the molecular weight (in terms of the number average degree of polymerization xn) of the polymer can be linked to the extent of reaction (p) using eqn (1). Thus, in the simplest case of a difunctional (AB) monomer, when 50% of the available groups have reacted, the number average degree of polymerization is only 2. The consequence of eqn (1) is that high molecular weights in step-growth polymerizations are associated with highly efficient reactions that do not have side-reactions. Notwithstanding this, the types of molecular weights associated with chain-growth processes are not encountered in these processes (except in the case of monomers with more than two reactive groups where hyper-branched or even cross-linked polymers are possible). There is an additional complication, namely the role of cyclization. Kricheldorf has recently shown that under perfect conditions cyclization is the ultimate fate of any polymerization reaction. Thus, under extremely high conversions the prediction given by eqn (1) would overestimate the actual molecular weights produced. Molecules that undergo step-growth polymerization must have at least two reactive functional groups. If the functionality is greater than this, for example, trifunctional, then hyperbranched polymers or even cross-linked systems can be formed. Commonly, this involves the reaction of two different reactive difunctional monomers.

Synthesis of Ultra-High Molecular Weight Polyacrylonitrile (UHMWPAN) by Aqueous Suspension Polymerization

2015 ◽  
Vol 1120-1121 ◽  
pp. 615-619
Author(s):  
Hui Yu Jiang ◽  
Mei Hua Zhou ◽  
Ding Pan
Keyword(s):  
Molecular Weight ◽  
Suspension Polymerization ◽  
Aqueous Suspension ◽  
Average Molecular Weight ◽  
Monomer Concentration ◽  
Polymerization Process ◽  
Polymerization Temperature ◽  
Different Temperatures ◽  
Total Monomer Concentration ◽  
Ultra High Molecular Weight

Acrylonitrile (AN) and itaconic acid (IA) were used to synthesize UHMWPAN by aqueous suspension method with 2,2’-azobisisobutyronitrile (AIBN) as the initiator and polyvinylalcohol (PVA) as the disperser at different temperatures (55°C~75°C) for different timings (1.0h~3.0h). The usage amounts of AN, IA, AIBN and PVA were also technical polymerization parameters used to obtain the optimal polymerization process. We found that the conversion and the viscosity average molecular weight both achieved the optimum levels when the conditions were as follows: the total monomer concentration (21wt%), the monomer ratio (AN: IA=98:2), the usage amount of the initiator (AIBN, 0.01wt%), the usage amount of the disperser (PVA, 0.1wt%), the polymerization temperature (70°C) and the polymerization time (2h).

Binary molybdenum-based catalyst for coordination polymerization of styrene

2016 ◽  
Vol 49 (5) ◽  
pp. 408-421 ◽  
Author(s):  
Jieting Geng ◽  
Youguo Shao ◽  
Feng Song ◽  
Feng Li ◽  
Jing Hua
Keyword(s):  
Molecular Weight ◽  
Catalyst Activity ◽  
Average Molecular Weight ◽  
Gel Permeation Chromatography ◽  
Catalyst System ◽  
Bulk Polymerization ◽  
Molar Ratio ◽  
Scanning Calorimetry ◽  
Coordination Polymerization ◽  
Co Catalyst

Coordination polymerization of styrene (St) using molybdenum pentachloride supported by phosphite ligand in the presence of metal organic compound was studied for the first time. The types of phosphite and co-catalysts significantly affected the catalytic activity of the molybdenum (V) (Mo(V)) active center and the number-average molecular weight ( Mn) of the resultant polymer. Among the examined catalysts, tri(nonylphenyl)phosphite (TNPP) ligand and AlOPhCH3( i-Bu)2 as co-catalyst provided the polymer with highest yield (up to 87.1%), metallocene as co-catalyst provided the polymer with highest Mn (up to 5.32 × 105). The effect of [P]/[Mo] molar ratio on catalyst activity of the polymerization was discussed and the structures of Mo·TNPP complexes were preliminarily studied by infrared (IR) and ultraviolet spectroscopies. Besides, the polystyrene (PS) samples synthesized through bulk polymerization and solution polymerization were characterized by gel permeation chromatography, IR, carbon 13 nuclear magnetic resonance, and differential scanning calorimetry, respectively, and the results indicated both of the PS had high molecular weight (approximately 105) and atactic structure. All these results demonstrated that Mo(V) catalyst system was very effective for St polymerization.

Molecular Weight Defined in Sol-Gel Analysis and Its Application to Evaluate Branching

1995 ◽  
Vol 68 (2) ◽  
pp. 287-296 ◽  
Author(s):  
Asahiro Ahagon
Keyword(s):  
Molecular Weight ◽  
Crosslink Density ◽  
Sol Gel ◽  
Average Molecular Weight ◽  
Degree Of Polymerization ◽  
Gel Point ◽  
Linear Polymers ◽  
Molecular Parameter ◽  
Branch Points ◽  
Number Average Molecular Weight

Abstract It is considered that many “linear” polymers are actually branched; however, it is difficult to show this with ordinary methods for an arbitrarily chosen polymer. Branching can be regarded as premature crosslinking below the gel point. Attention is then paid to the well-established Charlesby-Pinner Equation used for sol-gel analysis in crosslinking studies. It contains the number average degree of polymerization before crosslinking as a parameter. The molecular parameter is considered here to be that of the virtual linear polymer which would be obtained by unlinking any branch points contained in the polymer. Evidence is shown to support this. It is then possible to estimate the total number of linear components on an average molecule of a branched polymer by taking the ratio of the number average molecular weight measured by two methods, i.e., sol-gel analysis and an ordinary method like GPC. Further information about the branching structure can be obtained by additional measurements of effective crosslink density for a series of polymers obtained from similar polymerization processes.

scholarly journals KINETIC HETEROGENEITY OF POLYMER PRODUCTS OBTAINED IN THE PRESENCE OF MICROHETEROGENIC CATALYTIC SYSTEMS BASED ON GEL CHROMATOGRAMS

2021 ◽  
Vol 18 (38) ◽  
pp. 27-37
Author(s):  
Eldar N. MIFTAKHOV ◽  
Svetlana A. MUSTAFINA ◽  
Ildus Sh NASYROV ◽  
Azat Kh DAMINOV
Keyword(s):  
Molecular Weight ◽  
Average Molecular Weight ◽  
Polymerization Process ◽  
Fredholm Integral Equations ◽  
Molecular Characteristics ◽  
Active Centers ◽  
Catalytic Systems ◽  
Polymer Product ◽  
Software Algorithms ◽  
Kinetic Heterogeneity

Background: the polymer product obtained in the presence of microheterogeneous catalytic systems is characterized by fairly molecular weight distribution (MWD), resulted from kinetically nonequivalent active centers (ACs) in the system that initiate the polymerization process. The nature and composition of ACs are determined by setting and solving an inverse problem on the formation of MWD. This problem is acute because revealing the nature of the kinetic heterogeneity explains changes in the molecular and consumer parameters of the product for different catalyst compositions and propagation modes in polymerizations. Aim: This study aimed to develop methods and algorithms for interpreting gel chromatograms to analyze the kinetic heterogeneity of a polymer product obtained industrially in microheterogeneous catalytic systems. Methods: the solution method is based on the assumption that the formed MWD is a superposition of distributions inherent in each type of ACs. Since the problem in the final formulation refers to the Fredholm integral equations of the first kind, the regularization method of A. N. Tikhonov is used for its numerical solution, with the original problem being preliminary discretized. This methodology and the developed software algorithms were used to determine the kinetic heterogeneity of titanium- and neodymium-containing catalytic systems. Results and discussion: The MWD analysis revealed two types of ACs with an average molecular weight of ATi-lnM = 11.3 and BTi-lnM = 13.2 in the titanium catalyst and three types of ACs ANd-lnM = 11.1, BNd-lnM = 12.7 and CNd-lnM = 14 for the neodymium catalyst, respectively. Conclusions: repeated computational experiments under different polymerization conditions and requirements for the preparation of a catalytic system make it possible to reveal a relationship with the resulting heterogeneity of ACs. It allows us to set and solve problems of controlling the molecular characteristics of the resulting polymer product.

Molecular Weight and Dispersity Affect Chain Conformation and pH-Response in Weak Polyelectrolyte Brushes

2021 ◽  
Author(s):  
Tzu-Han Li ◽  
Megan L. Robertson ◽  
Jacinta C. Conrad
Keyword(s):  
Molecular Weight ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Degree Of Polymerization ◽  
Chain Conformation ◽  
Average Degree ◽  
Polyelectrolyte Brushes ◽  
Ph Response ◽  
The Impact

The impact of brush molecular weight distribution on the conformation and response of weak polyacid brushes was investigated. We show that weight-average degree of polymerization (N_w) and dispersity (Ð) alter...

Simulation for Polymerization Process of Styrene Butadiene Rubber (SBR)

2010 ◽  
Vol 148-149 ◽  
pp. 1661-1667
Author(s):  
Kai Gu ◽  
Xiao Di Xu ◽  
Ming Zhao
Keyword(s):  
Molecular Weight ◽  
Process Model ◽  
Average Molecular Weight ◽  
Polymerization Process ◽  
Styrene Butadiene Rubber ◽  
Butadiene Rubber ◽  
Weight Average Molecular Weight ◽  
Sensitivity Analysis Method ◽  
Increasing Temperature ◽  
Styrene Butadiene

In this paper, Polymer Plus of Aspen Tech Inc. is used to establish a styrene-butadiene rubber (SBR) polymerization process model; the sensitivity analysis method is used to analyze concentration of the initiator, reaction temperature and other factors which influence production and molecular weight of product. It is concluded that increasing amount of initiator can improve production, while the molecular weight would increase at first and then decline; and along with the increasing temperature, weight-average molecular weight would lower and production of polymer PBS would increase; molecular weight of polymer and production of polymer would magnify along with increase of amount of emulsifier and volume of the reactor.

Cascade theory and the molecular weight averages of the sol fraction

1963 ◽  
Vol 272 (1348) ◽  
pp. 54-59 ◽  
Keyword(s):  
Molecular Weight ◽  
Stochastic Processes ◽  
Degree Of Polymerization ◽  
Average Degree ◽  
Branched Polymers ◽  
Cascade Theory

Gordon (1962) discussed the distribution of branched polymers in solution with the help of the cascade or branching theory of stochastic processes, and dealt both with systems of copolymers and homopolymers. The present paper is concerned primarily with the latter simpler case, and the main purpose is to use cascade theory to obtain formulae for the weight average and z-average degree of polymerization of the sol fraction .

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