Role of important parameters in ring opening polymerization of polylactide

2011 ◽  
Vol 31 (2-3) ◽  
Author(s):  
Paramjit Kaur ◽  
Rajeev Mehta ◽  
Sidh Nath Upadhyay
Keyword(s):  
Molecular Weight ◽  
Ring Opening ◽  
Side Reaction ◽  
Polymerization Reaction ◽  
Polymerization Temperature ◽  
Polymer Yield ◽  
A Value ◽  
Prolonged Reaction Time ◽  
Anhydrous Solvent

Abstract Different parameters, namely polymerization temperature, polymerization time, monomer/initiator ratio, nature of the initiator, amount of water or other impurities etc. are very significant for polymerization reactions either in bulk or solution. Monomer to initiator ratio has a very significant role in polymerization reactions and a value ranging from 50 to 5000 that has been reported by different researchers. Recrystallization of the monomer removes the meso compounds from the monomer, which absorbs the moisture and effects polymerization reaction. So, it is necessary to recrystallize the monomer with any anhydrous solvent like dry toluene, ethyl acetate etc. Prolonged reaction time cannot increase the polymer yield; it generally causes the decrease of molecular weight and broadening of molecular weight distribution of formed polymers. This is probably due to the transesterification side reaction in polymerization, intensifying at prolonged time periods. Several groups like hydroxyl and carboxylic acid affect the polymerization rate.

scholarly journals Synthesis of Poly(L-lactide) via Solvothermal Method

2009 ◽  
Vol 2009 ◽  
pp. 1-7 ◽  
Author(s):  
Ling Fang ◽  
Rongrong Qi ◽  
Linbo Liu ◽  
Gongwen Juan ◽  
Suangwu Huang
Keyword(s):  
Molecular Weight ◽  
Ring Opening ◽  
Solvothermal Method ◽  
Polymerization Reaction ◽  
Effect Of Solvents ◽  
Ring Opening Reaction ◽  
Optimal Reaction Condition ◽  
Temperature Time ◽  
Optimal Reaction ◽  
Ubbelohde Viscometer

Poly(L-lactide) was obtained from the ring-opening polymerization of L-lactide through a solvothermal process. Tin (II) chloride (SnC12) was used as the catalyst for the polymerization reaction. The focus of this paper was on the effect of solvents, catalyst usage, temperature, time, and antioxidants on the ring-opening reaction in the solvothermal synthesis. Ubbelohde viscometer, FTIR, GPC, and DSC were used to characterize the products. It is found that the optimal reaction condition for the highest molecular weight of PLA is at160∘Cfor 10 hour with 0.4% SnCl2in 10 mL toluene as solvent, and the high crystallinity can be obtained. The addition of antioxidant prior to the polymerization is conducive to obtaining high molecular weight and augmentTm,TcandXcvalues of PLA.

Experiment Research on Influence Factors of Ring-Opening Polymerization in Making PDLLA

2011 ◽  
Vol 183-185 ◽  
pp. 1879-1882
Author(s):  
Song Liu ◽  
Li Na Sun
Keyword(s):  
Molecular Weight ◽  
Ring Opening ◽  
Influence Factors ◽  
Ring Opening Polymerization ◽  
Polymerization Temperature ◽  
Experiment Research ◽  
Time Duration ◽  
Vacuum Degree ◽  
Temperature Time ◽  
Polymerization Conditions

The paper research on the factors of the lactide polymerization, which primarily were ontology purity, dosage of initiator, polymerization temperature, time and vacuum degree, etc. According to the molecular weight measuring in different conditions of synthesis PDLLA, the results shows that, through the control of polymerization conditions higher molecular weight of PDLLA can obtain, main parameters as the quality ratio of initiator and monomers is about 0.03%, the polymerization temperature is 140°C, time duration is 48h and vacuum is 0.05 mmHg.

Novel unsaturated ε-caprolactone polymerizable by ringopening and ring-opening metathesis mechanisms

e-Polymers ◽  
2002 ◽  
Vol 2 (1) ◽  
Author(s):  
Xudong Lou ◽  
Christophe Detrembleur ◽  
Philippe Lecomte ◽  
Robert Jérôme
Keyword(s):  
Molecular Weight ◽  
Ring Opening ◽  
Unsaturated Polyester ◽  
Side Reaction ◽  
Monomer Conversion ◽  
Ring Opening Metathesis Polymerization ◽  
Aliphatic Polyesters ◽  
Metathesis Polymerization ◽  
Insertion Mechanism ◽  
Alternative Routes

AbstractRing-opening polymerization (ROP) and ring-opening metathesis polymerization (ROMP) of an unsaturated ε-caprolactone, 6,7-dihydro-2(3H)-oxepinone (DHO2), are alternative routes to produce unsaturated aliphatic polyesters with the same molecular structure. Polymerization of DHO2 initiated by Al isopropoxide in toluene at room temperature or at 0°C proceeds by a coordination-insertion mechanism, although intramolecular transesterification takes place beyond complete monomer conversion. The molecular weight distribution is narrow as long as monomer conversion does not exceed 90%. Ring-opening metathesis polymerization of DHO2 initiated by Schrock’s Mo-based catalyst, 1, at 60°C allows higher molecular weight unsaturated polyester to be prepared, even though an intramolecular side reaction also operates. The structure of poly(DHO2) synthesized by ROP and ROMP is the same, as confirmed by 1H, 13C NMR, and FT-IR spectra. Copolymers of DHO2 with norbornene, cis-cyclooctene, and 1,5-cyclooctadiene have been successfully prepared.

scholarly journals Glycol-functionalized ionic liquids for high-temperature enzymatic ring-opening polymerization

RSC Advances ◽  
2018 ◽  
Vol 8 (63) ◽  
pp. 36025-36033 ◽  
Author(s):  
Hua Zhao ◽  
Lennox O. Afriyie ◽  
Nathaniel E. Larm ◽  
Gary A. Baker
Keyword(s):  
Thermal Stability ◽  
Molecular Weight ◽  
Ionic Liquids ◽  
High Temperature ◽  
High Molecular Weight ◽  
Ring Opening ◽  
Ring Opening Polymerization ◽  
High Thermal Stability ◽  
Polymerization Reaction

New glycol-functionalized ionic liquids exhibit high thermal stability and are lipase-compatible, leading to a high molecular weight of polyester in the enzymatic ring-opening polymerization reaction.

Kinetic parameters estimation of ring-opening poly(lactic acid) polymerization by modeling and simulation

2011 ◽  
Vol 31 (2-3) ◽  
Author(s):  
Rajeev Mehta ◽  
Vineet Kumar ◽  
Sidh Nath Upadhyay
Keyword(s):  
Molecular Weight ◽  
Lactic Acid ◽  
Rate Constants ◽  
Ring Opening ◽  
Numerical Technique ◽  
Kinetic Scheme ◽  
Degree Of Polymerization ◽  
Parameters Estimation ◽  
Polymerization Reaction ◽  
Poly Lactic Acid

Abstract The modeling of ring-opening polymerization of lactide to poly(lactic acid) (PLA) has been carried out. Carothers first synthesized PLA in 1932. Since then, hundreds of research papers and patents have appeared in the literature. However, there is a lack of data concerning the rate constants for initiation, propagation and termination steps of PLA polymerization, except some data about the apparent rate constant. This work investigates, theoretically, the individual rate constants using a simple numerical technique. The progress of lactide polymerization can be modeled by assuming a ring opening reaction mechanism comprising chain initiation, chain propagation, and chain termination. The simulator developed, based on the solutionof differential equations corresponding to the above-mentioned kinetic scheme, Generates a detailed molecular weight distribution that can be used to estimate average molecular weights (or average degree of polymerization) vs. polymerization time curves. These simulated curves, on matching with the reported experimental data (for different catalysts), yield the absolute values of rate constants. The values have been determined for zinc lactate. Rate constants could be determined by using the molecular weight and the polydispersity vs. polymerization data. This methodology offers greater opportunity for capturing high, non-equilibrium polymer yield through appropriately timed termination of the polymerization reaction.

scholarly journals Effect of Polymerization Conditions on Thermal and Mechanical Properties of Ethylene/1-Butene Copolymer Made with Ziegler-Natta Catalysts

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Mostafizur Rahaman ◽  
M. Anwar Parvez ◽  
J. B. P. Soares ◽  
I. A. Hussein
Keyword(s):  
Mechanical Properties ◽  
Molecular Weight ◽  
Yield Stress ◽  
Hydrogen Pressure ◽  
Polymerization Reaction ◽  
Polymerization Temperature ◽  
Thermal And Mechanical Properties ◽  
Ethylene Pressure ◽  
Polymerization Conditions ◽  
Ziegler Natta Catalysts

The effect of polymerization conditions on thermal and mechanical properties of ethylene/1-butene copolymers synthesized through titanium-magnesium-supported Ziegler-Natta catalysts was studied. The increase in hydrogen pressure leads to a decrease in molecular weight (MW), storage modulus, and melting temperature. However, it yields an increase in molecular weight distribution (MWD),tan⁡δ, % crystallinity, tensile modulus, yield stress, and strain at break. The effects of ethylene pressure and polymerization temperature on the copolymer MW, MWD and thermal and mechanical properties have been investigated. However, the impacts of ethylene pressure and polymerization temperature on copolymer modulus, tensile strength, % crystallinity, crystallization peak temperature, yield stress, strain at break, and yield strain are marginal. The hydrogen pressure plays a major role in controlling the copolymer properties because it acts as an efficient chain transfer agent during polymerization reaction. The MW is the key parameter that influences flow activation energy. However, the other mechanical, dynamic mechanical, and thermal properties not only depend on MW but are also influenced by other parameters.

Endangered Butterflies and their Non-Native Host Plants: Examining Shifting Values of Belonging in Restoration

2019 ◽  
Vol 3 (1) ◽  
pp. 1-9
Author(s):  
Robert M. Anderson ◽  
Amy M. Lambert
Keyword(s):  
Ecological Restoration ◽  
Native Species ◽  
Puget Sound ◽  
A Value ◽  
The Social ◽  
Remote Island ◽  
Scientific Truth ◽  
Native Host

The island marble butterfly (Euchloe ausonides insulanus), thought to be extinct throughout the 20th century until re-discovered on a single remote island in Puget Sound in 1998, has become the focus of a concerted protection effort to prevent its extinction. However, efforts to “restore” island marble habitat conflict with efforts to “restore” the prairie ecosystem where it lives, because of the butterfly’s use of a non-native “weedy” host plant. Through a case study of the island marble project, we examine the practice of ecological restoration as the enactment of particular norms that define which species are understood to belong in the place being restored. We contextualize this case study within ongoing debates over the value of “native” species, indicative of deep-seated uncertainties and anxieties about the role of human intervention to alter or manage landscapes and ecosystems, in the time commonly described as the “Anthropocene.” We interpret the question of “what plants and animals belong in a particular place?” as not a question of scientific truth, but a value-laden construct of environmental management in practice, and we argue for deeper reflexivity on the part of environmental scientists and managers about the social values that inform ecological restoration.

Perempuan dan Liminalitas dalam Tradisi Perkawinan Adat di Timor Tengah Selatan

2020 ◽  
Vol 6 (1) ◽  
pp. 114
Author(s):  
Marsel Eliaser Liunokas
Keyword(s):  
Qualitative Research ◽  
Research Method ◽  
Literature Study ◽  
Qualitative Research Method ◽  
South Central ◽  
A Value ◽  
Traditional Marriage ◽  
The Village ◽  
As If

Timorese culture is patriarchal in that men are more dominant than women. As if women were not considered in traditional rituals so that an understanding was built that valued women lower than men. However, in contrast to the article to be studied, this would like to see the priority of women’s roles in traditional marriages in Belle village, South Central Timor. The role of women wiil be seen from giving awards to their parents called puah mnasi manu mnasi. This paper aims to look at the meaning of the rituals of puah mnasi maun mnasi and the role and strengths that women have in traditional marriage rituals in the village of Belle, South Central Timor. The method used for this research is a qualitative research method using interview techniques with a number of people in the Belle Villa community and literature study to strengthen this writing. Based on the data obtained this paper shows that the adat rituals of puah mnasi manu mnasi provide a value that can be learned, namely respect for women, togetherness between the two families, and brotherhood that is intertwined due to customary marital affrairs.

Influence of social networks on business processes’ development

2020 ◽  
Vol 19 (12) ◽  
pp. 2225-2252
Author(s):  
E.V. Popov ◽  
V.L. Simonova ◽  
O.V. Komarova ◽  
S.S. Kaigorodova
Keyword(s):  
Social Networks ◽  
Social Media ◽  
Business Models ◽  
Business Processes ◽  
Digital Economy ◽  
Theoretical Understanding ◽  
Sales Channels ◽  
A Value ◽  
The Impact

Subject. The emergence of new ways of interaction between sellers and buyers, the formation of new sales channels and product promotion based on the use of digital economy tools is at the heart of improving the business processes. Social networks became a tool for development; their rapid growth necessitates theoretical understanding and identification of potential application in enterprise's business process digitalization. Objectives. We explore the role of social media in the digitalization of business processes, systematize the impact of social networks on business processes of enterprises in the digital economy. Methods. The theoretical and methodological analysis of social networks as a tool for digitalization of company's business processes rests on the content analysis of domestic and foreign scientific studies, comparison, generalization and systematization. Results. We highlight the key effects of the impact of social networks on the business processes of the company; show that the digitalization of business processes should be considered in the context of a value-based approach, aimed at creating a value through the algorithmization of company operations. We determine that social networks are one of the most important tools for digitalization of company's business processes, as they have a high organizational and management potential. We also systematize the effects of social media on company's business processes. Conclusions. We present theoretical provisions of the impact of social networks on business processes of enterprises, which will enable to model and organize ideas about the development of digital ecosystems and the formation of business models.

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