Rheological and mechanical properties and interfacial stress development of composite cements modified with thio-urethane oligomers

Ataís Bacchi, Carmem Pfeifer

Research output: Contribution to journalArticle

19 Citations (Scopus)

Abstract

Objectives: Thio-urethane oligomers have been shown to reduce stress and increase toughness in highly filled composite materials. This study evaluated the influence of thio-urethane backbone structure on rheological and mechanical properties of resin cements modified with a fixed concentration of the oligomers. Methods: Thio-urethane oligomers (TU) were synthesized by combining thiols - pentaerythritol tetra-3-mercaptopropionate (PETMP) or trimethylol-tris-3-mercaptopropionate (TMP) - with isocyanates - 1,6-hexanediol-diissocyante (HDDI) (aliphatic) or 1,3-bis(1-isocyanato-1-methylethyl)benzene (BDI) (aromatic) or dicyclohexylmethane 4,4'-diisocyanate (HMDI) (cyclic), at 1:2 isocyanate:thiol, leaving pendant thiols. 20wt% TU were added to BisGMA-UDMA-TEGDMA (5:3:2). 60wt% silanated inorganic fillers were added. Near-IR was used to follow methacrylate conversion and rate of polymerization (Rpmax). Mechanical properties were evaluated in three-point bending (ISO 4049) for flexural strength/modulus (FS/FM, and toughness), and notched specimens (ASTM Standard E399-90) for fracture toughness (K IC). PS was measured on the Bioman. Viscosity (V) and gel-points (defined as the crossover between storage and loss shear moduli (G'/G″)) were obtained with rheometry. Glass transition temperature (T g), cross-link density and homogeneity of the network were obtained with dynamic mechanical analysis. Film-thickness was evaluated according to ISO 4049. Results: DC and mechanical properties increased and Rpmax and PS decreased with the addition of TUs. Gelation (G'/G″) was delayed and DC at G'/G″ increased in TU groups. T g and cross-link density dropped in TU groups, while oligomers let to more homogenous networks. An increase in V was observed, with no effect on film-thickness. Significant reductions in PS were achieved at the same time conversion and mechanical properties increased. Significance: The addition of thio-urethane oligomers proved successful in improving several key properties of resin cements, without disrupting the procedures dentists use to polymerize the material. This approach has potential to be translated to commercial materials very readily.

Original languageEnglish (US)
JournalDental Materials
DOIs
StateAccepted/In press - Dec 4 2015

Fingerprint

Urethane
Oligomers
Cements
Mechanical properties
Composite materials
Sulfhydryl Compounds
Resin Cements
Isocyanates
Toughness
Film thickness
Resins
Methacrylates
Transition Temperature
Benzene
Dentists
Viscosity
Polymerization
Dynamic mechanical analysis
Gelation
Glass

Keywords

  • Dynamic mechanical analysis
  • Mechanical strength
  • Polymerization stress
  • Resin cements
  • Rheological properties
  • Thio-urethane oligomers

ASJC Scopus subject areas

  • Dentistry(all)
  • Materials Science(all)
  • Mechanics of Materials

Cite this

@article{ce1846d8992949ec9278abce14cfe5b5,
title = "Rheological and mechanical properties and interfacial stress development of composite cements modified with thio-urethane oligomers",
abstract = "Objectives: Thio-urethane oligomers have been shown to reduce stress and increase toughness in highly filled composite materials. This study evaluated the influence of thio-urethane backbone structure on rheological and mechanical properties of resin cements modified with a fixed concentration of the oligomers. Methods: Thio-urethane oligomers (TU) were synthesized by combining thiols - pentaerythritol tetra-3-mercaptopropionate (PETMP) or trimethylol-tris-3-mercaptopropionate (TMP) - with isocyanates - 1,6-hexanediol-diissocyante (HDDI) (aliphatic) or 1,3-bis(1-isocyanato-1-methylethyl)benzene (BDI) (aromatic) or dicyclohexylmethane 4,4'-diisocyanate (HMDI) (cyclic), at 1:2 isocyanate:thiol, leaving pendant thiols. 20wt{\%} TU were added to BisGMA-UDMA-TEGDMA (5:3:2). 60wt{\%} silanated inorganic fillers were added. Near-IR was used to follow methacrylate conversion and rate of polymerization (Rpmax). Mechanical properties were evaluated in three-point bending (ISO 4049) for flexural strength/modulus (FS/FM, and toughness), and notched specimens (ASTM Standard E399-90) for fracture toughness (K IC). PS was measured on the Bioman. Viscosity (V) and gel-points (defined as the crossover between storage and loss shear moduli (G'/G″)) were obtained with rheometry. Glass transition temperature (T g), cross-link density and homogeneity of the network were obtained with dynamic mechanical analysis. Film-thickness was evaluated according to ISO 4049. Results: DC and mechanical properties increased and Rpmax and PS decreased with the addition of TUs. Gelation (G'/G″) was delayed and DC at G'/G″ increased in TU groups. T g and cross-link density dropped in TU groups, while oligomers let to more homogenous networks. An increase in V was observed, with no effect on film-thickness. Significant reductions in PS were achieved at the same time conversion and mechanical properties increased. Significance: The addition of thio-urethane oligomers proved successful in improving several key properties of resin cements, without disrupting the procedures dentists use to polymerize the material. This approach has potential to be translated to commercial materials very readily.",
keywords = "Dynamic mechanical analysis, Mechanical strength, Polymerization stress, Resin cements, Rheological properties, Thio-urethane oligomers",
author = "Ata{\'i}s Bacchi and Carmem Pfeifer",
year = "2015",
month = "12",
day = "4",
doi = "10.1016/j.dental.2016.05.003",
language = "English (US)",
journal = "Dental Materials",
issn = "0109-5641",
publisher = "Elsevier Science",

}

TY - JOUR

T1 - Rheological and mechanical properties and interfacial stress development of composite cements modified with thio-urethane oligomers

AU - Bacchi, Ataís

AU - Pfeifer, Carmem

PY - 2015/12/4

Y1 - 2015/12/4

N2 - Objectives: Thio-urethane oligomers have been shown to reduce stress and increase toughness in highly filled composite materials. This study evaluated the influence of thio-urethane backbone structure on rheological and mechanical properties of resin cements modified with a fixed concentration of the oligomers. Methods: Thio-urethane oligomers (TU) were synthesized by combining thiols - pentaerythritol tetra-3-mercaptopropionate (PETMP) or trimethylol-tris-3-mercaptopropionate (TMP) - with isocyanates - 1,6-hexanediol-diissocyante (HDDI) (aliphatic) or 1,3-bis(1-isocyanato-1-methylethyl)benzene (BDI) (aromatic) or dicyclohexylmethane 4,4'-diisocyanate (HMDI) (cyclic), at 1:2 isocyanate:thiol, leaving pendant thiols. 20wt% TU were added to BisGMA-UDMA-TEGDMA (5:3:2). 60wt% silanated inorganic fillers were added. Near-IR was used to follow methacrylate conversion and rate of polymerization (Rpmax). Mechanical properties were evaluated in three-point bending (ISO 4049) for flexural strength/modulus (FS/FM, and toughness), and notched specimens (ASTM Standard E399-90) for fracture toughness (K IC). PS was measured on the Bioman. Viscosity (V) and gel-points (defined as the crossover between storage and loss shear moduli (G'/G″)) were obtained with rheometry. Glass transition temperature (T g), cross-link density and homogeneity of the network were obtained with dynamic mechanical analysis. Film-thickness was evaluated according to ISO 4049. Results: DC and mechanical properties increased and Rpmax and PS decreased with the addition of TUs. Gelation (G'/G″) was delayed and DC at G'/G″ increased in TU groups. T g and cross-link density dropped in TU groups, while oligomers let to more homogenous networks. An increase in V was observed, with no effect on film-thickness. Significant reductions in PS were achieved at the same time conversion and mechanical properties increased. Significance: The addition of thio-urethane oligomers proved successful in improving several key properties of resin cements, without disrupting the procedures dentists use to polymerize the material. This approach has potential to be translated to commercial materials very readily.

AB - Objectives: Thio-urethane oligomers have been shown to reduce stress and increase toughness in highly filled composite materials. This study evaluated the influence of thio-urethane backbone structure on rheological and mechanical properties of resin cements modified with a fixed concentration of the oligomers. Methods: Thio-urethane oligomers (TU) were synthesized by combining thiols - pentaerythritol tetra-3-mercaptopropionate (PETMP) or trimethylol-tris-3-mercaptopropionate (TMP) - with isocyanates - 1,6-hexanediol-diissocyante (HDDI) (aliphatic) or 1,3-bis(1-isocyanato-1-methylethyl)benzene (BDI) (aromatic) or dicyclohexylmethane 4,4'-diisocyanate (HMDI) (cyclic), at 1:2 isocyanate:thiol, leaving pendant thiols. 20wt% TU were added to BisGMA-UDMA-TEGDMA (5:3:2). 60wt% silanated inorganic fillers were added. Near-IR was used to follow methacrylate conversion and rate of polymerization (Rpmax). Mechanical properties were evaluated in three-point bending (ISO 4049) for flexural strength/modulus (FS/FM, and toughness), and notched specimens (ASTM Standard E399-90) for fracture toughness (K IC). PS was measured on the Bioman. Viscosity (V) and gel-points (defined as the crossover between storage and loss shear moduli (G'/G″)) were obtained with rheometry. Glass transition temperature (T g), cross-link density and homogeneity of the network were obtained with dynamic mechanical analysis. Film-thickness was evaluated according to ISO 4049. Results: DC and mechanical properties increased and Rpmax and PS decreased with the addition of TUs. Gelation (G'/G″) was delayed and DC at G'/G″ increased in TU groups. T g and cross-link density dropped in TU groups, while oligomers let to more homogenous networks. An increase in V was observed, with no effect on film-thickness. Significant reductions in PS were achieved at the same time conversion and mechanical properties increased. Significance: The addition of thio-urethane oligomers proved successful in improving several key properties of resin cements, without disrupting the procedures dentists use to polymerize the material. This approach has potential to be translated to commercial materials very readily.

KW - Dynamic mechanical analysis

KW - Mechanical strength

KW - Polymerization stress

KW - Resin cements

KW - Rheological properties

KW - Thio-urethane oligomers

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