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Poly(Lactic Acid) Block Copolymers : = Synthesis, Characterization, and Structure-Property Relationships = Polymilchsaure-Blockcopolymere.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Poly(Lactic Acid) Block Copolymers :/
Reminder of title:	Synthesis, Characterization, and Structure-Property Relationships = Polymilchsaure-Blockcopolymere.
remainder title:	Polymilchsaure-Blockcopolymere.
Author:	Hernandez, Benjamin Rodriguez.
Description:	1 online resource (174 pages)
Notes:	Source: Dissertations Abstracts International, Volume: 84-04, Section: A.
Contained By:	Dissertations Abstracts International84-04A.
Subject:	Mechanical properties. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=29417846click for full text (PQDT)
ISBN:	9798352650295

Poly(Lactic Acid) Block Copolymers : = Synthesis, Characterization, and Structure-Property Relationships = Polymilchsaure-Blockcopolymere.
Hernandez, Benjamin Rodriguez.

Poly(Lactic Acid) Block Copolymers :Synthesis, Characterization, and Structure-Property Relationships = Polymilchsaure-Blockcopolymere.Polymilchsaure-Blockcopolymere. - 1 online resource (174 pages)

Source: Dissertations Abstracts International, Volume: 84-04, Section: A.

Thesis (Ph.D.)--Technische Universitaet Berlin (Germany), 2022.

Includes bibliographical references

Poly(L-lactic acid) (PLLA) is currently the bio-based, biodegradable, and recyclable synthetic polymer with the highest installed production capacity in the world. The environmentally favorable characteristics of PLLA make it attractive for applications in which its biodegradability can prevent the leakage of plastics into the environment (organic waste collection films, agricultural mulch films) or where separation from organic material in direct contact makes recycling unfeasible (food packaging). The relatively high elastic modulus and low elongation at break of pure PLLA however, make for stiff and brittle films that cannot be used in many of the before-mentioned applications. At the same time, PLLA exhibits a relatively low melt strength and low melt viscosity when compared to conventional flexible film-grade materials, which makes processing of PLLA in conventional equipment difficult.In the present work, the mechanical and rheological property profile of PLLA is modified through the synthesis of high molar mass PLLA-b-polyether-b-PLLA block copolymers in an industrially feasible synthesis method. To achieve this, high molar mass polyether diols are used as macroinitiators in the ring opening polymerization (ROP) of L-lactide under similar conditions to those used for the industrial synthesis of conventional PLLA homopolymers (bulk, tin(II) 2-ethylhexanoate [Sn(Oct)2] catalyst, T ~ 180 °C). Different chemical structures of the polyether middle block are introduced into the copolymers by using polyether macroinitiators of different chemical structure (i.e. polyethylene glycol [PEG], polypropylene glycol [PPG], poly(ethylene-co-propylene glycol [PEPG]). The chemical structure of the outer PLLA blocks is modified by using other ring comonomers that are able to undergo copolymerization with the L-lactide monomer at the same reaction conditions (i.e. D-lactide, ε-caprolactone [CL]). Additionally, tetrafunctional PEPG macroinitiators are used to synthesize PLLA>b-polyether-b<PLLA block copolymers with a star topology. To obtain the highest possible block copolymer molar mass values (and thus higher melt viscosities), optimizations during the block copolymer synthesis are studied. Tris(nonylphenyl) phosphite (TNPP) is used to reduce the molar mass degradation reactions during synthesis, and the catalyst concentration is lowered to reduce the molar mass degradation reactions during subsequent processing of the block copolymers.The effects of the different synthesized block copolymer chemical structures on the thermal, mechanical, and rheological properties are systematically investigated through the use of differential scanning calorimetry (DSC), tensile testing, melt flow index (MFI), and oscillatory rheometry to establish a series of structure-property relationships. Changes in the chemical structure of the block copolymers are found to cause changes in the glass transition temperature (Tg) and peak melting temperature (Tm). The changes in the thermal properties are found to significantly affect the mechanical and rheological properties of the block copolymers. The established structure-property relationships are used to design PLLA-b-polyether-b-PLLA block copolymer structures with the required mechanical and rheological properties for flexible blown film applications. The resulting block copolymers are successfully processed under stable conditions in a conventional blown film extrusion line. The obtained blown films have relatively low elastic moduli of around 140 MPa and elongation at break values above 400 %, which are comparable to commercial flexible film materials.

Electronic reproduction.
Ann Arbor, Mich. :
ProQuest,
2023

Mode of access: World Wide Web

ISBN: 9798352650295Subjects--Topical Terms:

3549505
Mechanical properties.
Index Terms--Genre/Form:

542853
Electronic books.

Poly(Lactic Acid) Block Copolymers : = Synthesis, Characterization, and Structure-Property Relationships = Polymilchsaure-Blockcopolymere.
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245 1 0 $a Poly(Lactic Acid) Block Copolymers : $b Synthesis, Characterization, and Structure-Property Relationships = Polymilchsaure-Blockcopolymere.
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500 $a Source: Dissertations Abstracts International, Volume: 84-04, Section: A.
500 $a Advisor: Lieske, Antje.
502 $a Thesis (Ph.D.)--Technische Universitaet Berlin (Germany), 2022.
504 $a Includes bibliographical references
520 $a Poly(L-lactic acid) (PLLA) is currently the bio-based, biodegradable, and recyclable synthetic polymer with the highest installed production capacity in the world. The environmentally favorable characteristics of PLLA make it attractive for applications in which its biodegradability can prevent the leakage of plastics into the environment (organic waste collection films, agricultural mulch films) or where separation from organic material in direct contact makes recycling unfeasible (food packaging). The relatively high elastic modulus and low elongation at break of pure PLLA however, make for stiff and brittle films that cannot be used in many of the before-mentioned applications. At the same time, PLLA exhibits a relatively low melt strength and low melt viscosity when compared to conventional flexible film-grade materials, which makes processing of PLLA in conventional equipment difficult.In the present work, the mechanical and rheological property profile of PLLA is modified through the synthesis of high molar mass PLLA-b-polyether-b-PLLA block copolymers in an industrially feasible synthesis method. To achieve this, high molar mass polyether diols are used as macroinitiators in the ring opening polymerization (ROP) of L-lactide under similar conditions to those used for the industrial synthesis of conventional PLLA homopolymers (bulk, tin(II) 2-ethylhexanoate [Sn(Oct)2] catalyst, T ~ 180 °C). Different chemical structures of the polyether middle block are introduced into the copolymers by using polyether macroinitiators of different chemical structure (i.e. polyethylene glycol [PEG], polypropylene glycol [PPG], poly(ethylene-co-propylene glycol [PEPG]). The chemical structure of the outer PLLA blocks is modified by using other ring comonomers that are able to undergo copolymerization with the L-lactide monomer at the same reaction conditions (i.e. D-lactide, ε-caprolactone [CL]). Additionally, tetrafunctional PEPG macroinitiators are used to synthesize PLLA>b-polyether-b<PLLA block copolymers with a star topology. To obtain the highest possible block copolymer molar mass values (and thus higher melt viscosities), optimizations during the block copolymer synthesis are studied. Tris(nonylphenyl) phosphite (TNPP) is used to reduce the molar mass degradation reactions during synthesis, and the catalyst concentration is lowered to reduce the molar mass degradation reactions during subsequent processing of the block copolymers.The effects of the different synthesized block copolymer chemical structures on the thermal, mechanical, and rheological properties are systematically investigated through the use of differential scanning calorimetry (DSC), tensile testing, melt flow index (MFI), and oscillatory rheometry to establish a series of structure-property relationships. Changes in the chemical structure of the block copolymers are found to cause changes in the glass transition temperature (Tg) and peak melting temperature (Tm). The changes in the thermal properties are found to significantly affect the mechanical and rheological properties of the block copolymers. The established structure-property relationships are used to design PLLA-b-polyether-b-PLLA block copolymer structures with the required mechanical and rheological properties for flexible blown film applications. The resulting block copolymers are successfully processed under stable conditions in a conventional blown film extrusion line. The obtained blown films have relatively low elastic moduli of around 140 MPa and elongation at break values above 400 %, which are comparable to commercial flexible film materials.
520 $a Poly(L-Milchsaure) (PLLA) ist derzeit das biobasierte, biologisch abbaubare und recycelbare synthetische Polymer mit der weltweit hochsten installierten Produktionskapazitat. Die umweltfreundlichen Eigenschaften von PLLA machen es attraktiv fur Anwendungen, bei denen seine biologische Abbaubarkeit das Austreten von Kunststoffen in die Umwelt verhindern kann (Folien fur die Sammlung organischer Abfalle, Mulchfolien fur die Landwirtschaft) oder bei denen die Trennung von organischen Abfalle das Recycling unmoglich macht (Lebensmittelverpackungen). Der relativ hohe Elastizitatsmodul und die niedrige Bruchdehnung von reinem PLLA fuhren jedoch zu steifen und sproden Folien, die fur viele der vorgenannten Anwendungen nicht geeignet sind. Gleichzeitig weist PLLA im Vergleich zu herkommlichen flexiblen Folienmaterialien eine relativ geringe Schmelzfestigkeit und niedrige Schmelzviskositat auf, was die Verarbeitung von PLLA in herkommlichen Anlagen erschwert.In der vorliegenden Arbeit wird das mechanische und rheologische Eigenschaftsprofil von PLLA durch die Synthese von hochmolekularen PLLA-b-Polyether-b-PLLA-Blockcopolymeren in einem industriell durchfuhrbaren Syntheseverfahren verandert. Dazu werden hochmolekulare Polyetherdiole als Makroinitiatoren in der Ringoffnungspolymerisation (ROP) von L-Lactid unter ahnlichen Bedingungen wie bei der industriellen Synthese herkommlicher PLLA-Homopolymere verwendet (Bulk, Zinn(II)-2-Ethylhexanoat [Sn(Oct)2]-Katalysator, T~180°C). Unterschiedliche chemische Strukturen des Polyether-Mittelblocks werden in die Copolymere eingefuhrt, indem Polyether-Makroinitiatoren unterschiedlicher chemischer Struktur verwendet werden (Polyethylenglykol [PEG], Polypropylenglykol [PPG], Poly(ethylen-co-propylenglykol [PEPG]). Die chemische Struktur der auseren PLLA-Blocke wird durch die Verwendung anderer Ringcomonomere modifiziert, die unter den gleichen Reaktionsbedingungen mit dem L-Lactid-Monomer copolymerisieren konnen (z.B. D-Lactid, ε-Caprolacton [CL]). Zusatzlich werden tetrafunktionelle PEPG-Makroinitiatoren verwendet, um PLLA>b-Polyether-b<PLLA-Blockcopolymere mit einer Sterntopologie zu synthetisieren. Um die hochstmoglichen Molmassenwerte der Blockcopolymere (und damit hohere Schmelzviskositaten) zu erreichen, werden Optimierungen wahrend der Blockcopolymersynthese untersucht. Tris(nonylphenyl)phosphit (TNPP) wird verwendet, um die Molmassenabbaureaktionen wahrend der Synthese zu reduzieren, und die Katalysatorkonzentration wird gesenkt, um die Molmassenabbaureaktionen wahrend der anschliesenden Verarbeitung der Blockcopolymere zu verringern.Die Auswirkungen der verschiedenen chemischen Strukturen der synthetisierten Blockcopolymere auf die thermischen, mechanischen und rheologischen Eigenschaften werden systematisch mit Hilfe der Differential-Scanning-Kalorimetrie (DSC), der Zugprufung, des Melt-Flow-Indexes (MFI) und der Oszillationsrheometrie untersucht, um eine Reihe von Struktur-Eigenschafts-Beziehungen zu definieren. Die Veranderungen in der chemischen Struktur der Blockcopolymere haben zu Veranderungen der Glasubergangstemperatur (Tg) und der Spitzenschmelztemperatur (Tm) gefuhrt. Es wurde festgestellt, dass die Veranderungen der thermischen Eigenschaften (Tg, Tm) die mechanischen und rheologischen Eigenschaften der Blockcopolymere erheblich beeinflussen. Die ermittelten Struktur-Eigenschafts-Beziehungen werden genutzt, um PLLA-b-Polyether-b-PLLA-Blockcopolymerstrukturen mit den erforderlichen mechanischen und rheologischen Eigenschaften fur flexible Blasfolienanwendungen zu entwickeln. Die resultierenden Blockcopolymere werden erfolgreich unter stabilen Bedingungen in einer konventionellen Blasfolienextrusionsanlage verarbeitet. Die erhaltenen Blasfolien haben relativ niedrige Elastizitatsmodule von etwa 140 MPa und Bruchdehnungswerte von uber 400 %, die mit kommerziellen flexiblen Folienmaterialien vergleichbar sind.
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538 $a Mode of access: World Wide Web
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