Effects of molecular weight and grafted maleic anhydride of functionalized polylactic acid used in reactive compatibilized binary and ternary blends of polylactic acid and thermoplastic cassava starch

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Abstract

Polylactic acid (PLA) was reactively functionalized with maleic anhydride (MA) and 2,5-bis(tert-butylperoxy)-2,5-dimethylhexane (Luperox 101 or L101) using a twin screw extruder (TSE). The effects of functionality (grafted MA level) and/or number average molecular weight of functionalized PLA (PLA-g-MA) as the reactive polymer pairs (binary blends) and reactive compatibilizer (ternary blends) were investigated. Due to the dominant side reaction during melt free radical grafting, polymer degradation or chain scission, PLA-g-MA having a higher grafted MA had lower molecular weights and intrinsic viscosity as well as broader molecular weight distribution values. The thermal, physical, mechanical, and morphological properties of binary blends produced by using the TSE and injection molding at a ratio of 70 wt % PLA-g-MA and 30 wt % thermoplastic cassava starch (TPCS) were analyzed. The reactive blends having grafted MA more than 0.4 wt % had poor tensile strength and elongation at break. Similar trends in morphology and tensile properties were observed in the reactive ternary blends. The use of PLA-g-MA strongly impacted the elongation at break but not the modulus or tensile strength. An increase of PLA-g-MA's number average molecular weight (M¯n or Mn) improved the tensile properties of the blends. The reactive ternary blend having 0.1 wt % grafted MA on PLA and PLA-g-MA basis and PLA-g-MA's Mn of 45 kDa offered the highest elongation at break.

LanguageEnglish (US)
Article number42230
JournalJournal of Applied Polymer Science
Volume132
Issue number28
DOIs
StatePublished - Jul 1 2015

Profile

Maleic Anhydrides
Maleic anhydride
Starch
Thermoplastics
Molecular weight
Acids
Elongation
Extruders
Tensile properties
Tensile strength
poly(lactic acid)
Functional polymers
Compatibilizers
Polymer blends
Molecular weight distribution
Free radicals
Injection molding
Free Radicals
Polymers

Keywords

  • biodegradable
  • biopolymers and renewable polymers
  • polyesters
  • polysaccharides
  • synthesis and processing

ASJC Scopus subject areas

  • Materials Chemistry
  • Polymers and Plastics
  • Surfaces, Coatings and Films
  • Chemistry(all)

Cite this

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title = "Effects of molecular weight and grafted maleic anhydride of functionalized polylactic acid used in reactive compatibilized binary and ternary blends of polylactic acid and thermoplastic cassava starch",
abstract = "Polylactic acid (PLA) was reactively functionalized with maleic anhydride (MA) and 2,5-bis(tert-butylperoxy)-2,5-dimethylhexane (Luperox 101 or L101) using a twin screw extruder (TSE). The effects of functionality (grafted MA level) and/or number average molecular weight of functionalized PLA (PLA-g-MA) as the reactive polymer pairs (binary blends) and reactive compatibilizer (ternary blends) were investigated. Due to the dominant side reaction during melt free radical grafting, polymer degradation or chain scission, PLA-g-MA having a higher grafted MA had lower molecular weights and intrinsic viscosity as well as broader molecular weight distribution values. The thermal, physical, mechanical, and morphological properties of binary blends produced by using the TSE and injection molding at a ratio of 70 wt {\%} PLA-g-MA and 30 wt {\%} thermoplastic cassava starch (TPCS) were analyzed. The reactive blends having grafted MA more than 0.4 wt {\%} had poor tensile strength and elongation at break. Similar trends in morphology and tensile properties were observed in the reactive ternary blends. The use of PLA-g-MA strongly impacted the elongation at break but not the modulus or tensile strength. An increase of PLA-g-MA's number average molecular weight (M¯n or Mn) improved the tensile properties of the blends. The reactive ternary blend having 0.1 wt {\%} grafted MA on PLA and PLA-g-MA basis and PLA-g-MA's Mn of 45 kDa offered the highest elongation at break.",
keywords = "biodegradable, biopolymers and renewable polymers, polyesters, polysaccharides, synthesis and processing",
author = "Sukeewan Detyothin and Selke, {Susan E M} and Ramani Narayan and Maria Rubino and Auras, {Rafael A.}",
year = "2015",
month = "7",
day = "1",
doi = "10.1002/app.42230",
language = "English (US)",
volume = "132",
journal = "Journal of Applied Polymer Science",
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T1 - Effects of molecular weight and grafted maleic anhydride of functionalized polylactic acid used in reactive compatibilized binary and ternary blends of polylactic acid and thermoplastic cassava starch

AU - Detyothin,Sukeewan

AU - Selke,Susan E M

AU - Narayan,Ramani

AU - Rubino,Maria

AU - Auras,Rafael A.

PY - 2015/7/1

Y1 - 2015/7/1

N2 - Polylactic acid (PLA) was reactively functionalized with maleic anhydride (MA) and 2,5-bis(tert-butylperoxy)-2,5-dimethylhexane (Luperox 101 or L101) using a twin screw extruder (TSE). The effects of functionality (grafted MA level) and/or number average molecular weight of functionalized PLA (PLA-g-MA) as the reactive polymer pairs (binary blends) and reactive compatibilizer (ternary blends) were investigated. Due to the dominant side reaction during melt free radical grafting, polymer degradation or chain scission, PLA-g-MA having a higher grafted MA had lower molecular weights and intrinsic viscosity as well as broader molecular weight distribution values. The thermal, physical, mechanical, and morphological properties of binary blends produced by using the TSE and injection molding at a ratio of 70 wt % PLA-g-MA and 30 wt % thermoplastic cassava starch (TPCS) were analyzed. The reactive blends having grafted MA more than 0.4 wt % had poor tensile strength and elongation at break. Similar trends in morphology and tensile properties were observed in the reactive ternary blends. The use of PLA-g-MA strongly impacted the elongation at break but not the modulus or tensile strength. An increase of PLA-g-MA's number average molecular weight (M¯n or Mn) improved the tensile properties of the blends. The reactive ternary blend having 0.1 wt % grafted MA on PLA and PLA-g-MA basis and PLA-g-MA's Mn of 45 kDa offered the highest elongation at break.

AB - Polylactic acid (PLA) was reactively functionalized with maleic anhydride (MA) and 2,5-bis(tert-butylperoxy)-2,5-dimethylhexane (Luperox 101 or L101) using a twin screw extruder (TSE). The effects of functionality (grafted MA level) and/or number average molecular weight of functionalized PLA (PLA-g-MA) as the reactive polymer pairs (binary blends) and reactive compatibilizer (ternary blends) were investigated. Due to the dominant side reaction during melt free radical grafting, polymer degradation or chain scission, PLA-g-MA having a higher grafted MA had lower molecular weights and intrinsic viscosity as well as broader molecular weight distribution values. The thermal, physical, mechanical, and morphological properties of binary blends produced by using the TSE and injection molding at a ratio of 70 wt % PLA-g-MA and 30 wt % thermoplastic cassava starch (TPCS) were analyzed. The reactive blends having grafted MA more than 0.4 wt % had poor tensile strength and elongation at break. Similar trends in morphology and tensile properties were observed in the reactive ternary blends. The use of PLA-g-MA strongly impacted the elongation at break but not the modulus or tensile strength. An increase of PLA-g-MA's number average molecular weight (M¯n or Mn) improved the tensile properties of the blends. The reactive ternary blend having 0.1 wt % grafted MA on PLA and PLA-g-MA basis and PLA-g-MA's Mn of 45 kDa offered the highest elongation at break.

KW - biodegradable

KW - biopolymers and renewable polymers

KW - polyesters

KW - polysaccharides

KW - synthesis and processing

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