Evaluating efficacy of different UV-stabilizers/absorbers in reducing UV-degradation of lignin

Holzforschung ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Saeid Nikafshar ◽  
Mojgan Nejad
Keyword(s):  
Lignin Degradation ◽  
Gel Permeation Chromatography ◽  
Wood Products ◽  
Uv Exposure ◽  
Resonance Spectroscopy ◽  
Uv Degradation ◽  
Scanning Calorimetry ◽  
Wood Coatings ◽  
Before And After ◽  
Uv Absorbers

Abstract Susceptibility of wood to UV degradation decreases the service life of wood products outdoors. Organic UV absorbers (UVAs) and hindered amine light stabilizers (HALSs), as well as inorganic UVAs, are added to coatings to improve the UV stability of coated-wood products. Although about 85% of UV radiation is absorbed by lignin in the wood, it is unclear which UV stabilizers can minimize lignin degradation. In this study, the photodegradation of softwood organosolv lignin was monitored over 35 days of UV exposure. Changes in lignin properties were assessed using Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), gel permeation chromatography (GPC), and phosphorus-31 nuclear magnetic resonance spectroscopy (31P NMR). It was found that the aromatic rings of lignin underwent significant degradation, resulting in increased glass transition temperature and molecular weight of lignin. Subsequently, 18 different additives were mixed with lignin and exposed to UV irradiation. The analysis of samples before and after UV exposure with FTIR revealed that inorganic UVAs (cerium oxide and zinc oxide) and a mixture of organic UVAs and HALSs (T-479/T-292, T-5248, and T-5333) were the most effective additives in reducing lignin degradation. This study can help coating scientists to formulate more durable transparent exterior wood coatings.

Chemical modification of nitrile rubber in the latex stage by functionalizing phosphorylated cardanol prepolymer: A bio-based plasticizer and a renewable resource

2018 ◽  
Vol 51 (2) ◽  
pp. 99-129 ◽  
Author(s):  
Satyajit Samantarai ◽  
Ahindra Nag ◽  
Nitesh Singh ◽  
Debabrata Dash ◽  
Amit Basak ◽  
...  
Keyword(s):  
Flow Behavior ◽  
Gel Permeation Chromatography ◽  
Renewable Resource ◽  
Mechanical Analysis ◽  
Resonance Spectroscopy ◽  
Butadiene Rubber ◽  
Scanning Calorimetry ◽  
Flow Behavior Index ◽  
Diphenyltetrazolium Bromide ◽  
Better Than

The present investigation deals with the functionalization of acrylonitrile butadiene rubber (NBR) by chemically grafting phosphorylated cardanol prepolymer (PCP) onto its backbone chain. The grafting of PCP onto NBR was accomplished in the latex stage successfully using benzoyl peroxide as the free radical initiator. The functionalized NBR (PCP- g-NBR) is characterized by ultraviolet–visible spectroscopy, Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, and gel permeation chromatography. PCP- g-NBR exhibited an increase in molecular weight (4.4%) with an increase in the polydispersity. The grafting parameters have been optimized using “Taguchi L9 table” and the optimum conditions were found to be “3 phr of initiator concentration, 15 phr of the PCP concentration, reaction temperature of 70°C and reaction time of 6 h.” The percentage grafting and grafting efficiency were calculated to be 7.28 and 80.37%, respectively, under optimum processing conditions. The PCP- g-NBR exhibited a reduction in Wallace plasticity number as well as the Mooney viscosity and an enhanced plasticity retention index (PRI) as compared to neat NBR. The rheological measurements exhibited a higher flow behavior index for PCP- g-NBR than the NBR itself. Differential scanning calorimetry and dynamic mechanical analysis results exhibited a decrease in glass transition temperature on functionalization of NBR confirming enhanced plasticization. Thermogravimetric analysis results displayed an increase in thermal stability of the functionalized NBR than that of virgin NBR. The physico-mechanical properties of the PCP- g-NBR vulcanizates were at par with or even better than the neat NBR vulcanizates. 3-(4,5-Dimethylthiazol-2yl)-2,5-diphenyltetrazolium bromide assay and hemolysis studies indicated NBR and PCP- g-NBR are nontoxic and biocompatible.

Controlled Synthesis and Processing of a Poly(L-lactide-co-ε-caprolactone) Copolymer for Biomedical Use as an Absorbable Monofilament Surgical Suture

2014 ◽  
Vol 894 ◽  
pp. 172-176 ◽  
Author(s):  
Sujitra Ruengdechawiwat ◽  
Runglawan Somsunan ◽  
Robert Molloy ◽  
Jintana Siripitayananon ◽  
Valerie J. Franklin ◽  
...  
Keyword(s):  
Gel Permeation Chromatography ◽  
Resonance Spectroscopy ◽  
Scanning Calorimetry ◽  
Surface Appearance ◽  
Analytical Technique ◽  
Surgical Suture ◽  
The Matrix ◽  
Hot Drawing ◽  
Matrix Morphology ◽  
Uniform Diameter

Poly (L-lactide-co-ε-caprolactone) 75:25 % mol, P(LL-co-CL), was synthesized via bulk ring-opening polymerisation (ROP) using a novel tin (II) alkoxide initiator, [Sn (Oct)]2DEG, at 130°C for 48 hrs. The effectiveness of this initiator was compared withthe well-known conventional tin (II) octoateinitiator, Sn (Oct)2. The P(LL-co-CL) copolymersobtained were characterized using a combination of analytical technique including: nuclear magnetic resonance spectroscopy (NMR), differential scanning calorimetry (DSC), thermogravimetry (TG) and gel permeation chromatography (GPC). The P(LL-co-CL) was melt-spun into monofilament fibres of uniform diameter and smooth surface appearance. Modification of the matrix morphology was then built into the as-spun fibresvia a series of controlled off-line annealing and hot-drawing steps.

scholarly journals Synthesis and Spectroscopic Analyses of New Polycarbonates Based on Bisphenol A-Free Components

Polymers ◽  
2021 ◽  
Vol 13 (24) ◽  
pp. 4437
Author(s):  
Krystyna Wnuczek ◽  
Andrzej Puszka ◽  
Beata Podkościelna
Keyword(s):  
Bisphenol A ◽  
Thermal Studies ◽  
Gel Permeation Chromatography ◽  
Resonance Spectroscopy ◽  
Scanning Calorimetry ◽  
Chromatography Analysis ◽  
Chemical Structures ◽  
New Synthesis ◽  
Characteristic Signal ◽  
Molecular Resonance

This paper discusses a new synthesis of bisphenol A-free polycarbonates based on four aliphatic-aromatic systems. In the first stage, different types of monomers (with/without sulfur) derived from diphenylmethane were synthesized. Then, new polycarbonates were prepared in the reactions with diphenyl carbonate (DPC) by transesterification and polycondensation reactions. Three different catalysts (zinc acetate, 4-(dimethylamino)pyridine and benzyltriethylammonium chloride) were tested. The structures of the compounds were confirmed by Nuclear Molecular Resonance spectroscopy (NMR) in each stage. The chemical structures of the obtained polycarbonates were verified by means of Attenuated Total Reflectance Fourier Transform infrared spectroscopy (ATR-FTIR). The presence of a carbonyl group in the infrared spectrum confirmed polycarbonate formation. Thermal studies by differential scanning calorimetry (DSC) were carried out to determine the melting temperatures of the monomers. A gel permeation chromatography analysis (GPC) of the polycarbonates was performed in order to investigate their molar masses. Thermal analysis proved the purity of the obtained monomers; the curves showed a characteristic signal of melting. The obtained polycarbonates were characterized as having high resistance to organic solvents, including tetrahydrofuran. The GPC analysis proved their relatively large molar masses and their low dispersity.

scholarly journals Effect of E-Beam Irradiation on Thermal and Mechanical Properties of Ester Elastomers Containing Multifunctional Alcohols

Polymers ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1043 ◽  
Author(s):  
Marta Piątek-Hnat ◽  
Kuba Bomba ◽  
Jakub Pęksiński ◽  
Agnieszka Kozłowska ◽  
Jacek G. Sośnicki ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Chemical Properties ◽  
Sebacic Acid ◽  
Gel Permeation Chromatography ◽  
Tensile Tests ◽  
Synthesis Process ◽  
Resonance Spectroscopy ◽  
Thermal And Mechanical Properties ◽  
Scanning Calorimetry ◽  
Water Contact

The aim of this work was to investigate the thermal and mechanical properties of novel, electron beam-modified ester elastomers containing multifunctional alcohols. Polymers tested in this work consist of two blocks: sebacic acid–butylene glycol block and sebacic acid–sugar alcohol block. Different sugar alcohols were utilized in the polymer synthesis: glycerol, sorbitol, xylitol, erythritol, and mannitol. The polymers have undergone an irradiation procedure. The materials were irradiated with doses of 50 kGy, 100 kGy, and 150 kGy. The expected effect of using ionizing radiation was crosslinking process and improvement of the mechanical properties. Additionally, a beneficial side effect of the irradiation process is sterilization of the affected materials. It is also worth noting that the materials described in this paper do not require either sensitizers or cross-linking agent in order to perform radiation modification. Radiation-modified poly(polyol sebacate-co-butylene sebacate) elastomers have been characterized in respect to the mechanical properties (quasi-static tensile tests), cross-link density, thermal properties (Differential Scanning Calorimetry (DSC)), chemical properties: Fourier transform infrared spectroscopy (FTIR), and wettability (water contact angle). Poly(polyol sebacate-co-butylene sebacate) preopolymers were characterized with nuclear magnetic resonance spectroscopy (1H NMR and 13C NMR) and gel permeation chromatography (GPC). Thermal stability of cross-linked materials (directly after synthesis process) was tested with thermogravimetric analysis (TGA).

scholarly journals P(N-Phenylmaleimide-Alt-Styrene) Introduced with 4-Carboxyl and Its Effect on the Heat Deflection Temperature of Nylon 6

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2330 ◽  
Author(s):  
Yufei Liu ◽  
Min He ◽  
Daohai Zhang ◽  
Qian Zhao ◽  
Yang Li ◽  
...  
Keyword(s):  
Dynamic Viscosity ◽  
Gel Permeation Chromatography ◽  
Nylon 6 ◽  
Mechanical Analysis ◽  
Radical Copolymerization ◽  
Resonance Spectroscopy ◽  
Scanning Calorimetry ◽  
Free Radical Copolymerization ◽  
Ft Ir ◽  
Heat Deflection Temperature

P(N-phenylmaleimide-alt-styrene) (P(NPMI-alt-St)) and P(N-(4-carboxyphenyl)maleimide-alt-styrene) (P(CPMI-alt-St)) were designed and synthesized via free radical copolymerization. Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance spectroscopy (1H NMR and 13C NMR), gel permeation chromatography (GPC), and differential scanning calorimetry (DSC) were used to confirm the structure of P(NPMI-alt-St) and P(CPMI-alt-St). Next, the effect of P(CPMI-alt-St) on the heat deflection temperature (HDT) of nylon 6 was studied. In comparison to the PA6/P(NPMI-alt-St) blend, with the addition of 10 wt %, the HDT value of the PA6/P(CPMI-alt-St) blend increased by 15.7 °C, and the glass transition temperature (Tg) by Dynamic mechanical analysis (DMA) increased 2.3 °C. According to the analysis of DMA, dynamic viscosity, and the SEM of PA6 and its blends, P(CPMI-alt-St) promoted its compatibility with PA6, and promoted the storage modulus and dynamic viscosity of the blends. Thus, the introduction of 4-carboxyl can significantly improve the effect of P(CPMI-alt-St) on the heat resistance modification of nylon 6.

scholarly journals Green process for green materials: viable low-temperature lipase-catalysed synthesis of renewable telechelics in supercritical CO 2

2015 ◽  
Vol 373 (2057) ◽  
pp. 20150073 ◽  
Author(s):  
S. Curia ◽  
A. F. Barclay ◽  
S. Torron ◽  
M. Johansson ◽  
S. M. Howdle
Keyword(s):  
Reaction Medium ◽  
Gel Permeation Chromatography ◽  
Side Reactions ◽  
Resonance Spectroscopy ◽  
Scanning Calorimetry ◽  
One Pot ◽  
Free System ◽  
Flight Mass Spectrometry ◽  
Green Materials ◽  
End Capping

We present a novel near-ambient-temperature approach to telechelic renewable polyesters by exploiting the unique properties of supercritical CO 2 (scCO 2 ). Bio-based commercially available monomers have been polymerized and functional telechelic materials with targeted molecular weight prepared by end-capping the chains with molecules containing reactive moieties in a one-pot reaction. The use of scCO 2 as a reaction medium facilitates the effective use of Candida antarctica Lipase B (CaLB) as a catalyst at a temperature as low as 35°C, hence avoiding side reactions, maintaining the end-capper functionality and preserving the enzyme activity. The functionalized polymer products have been characterized by 1 H nuclear magnetic resonance spectroscopy, matrix-assisted laser desorption/ionization–time-of-flight mass spectrometry, gel permeation chromatography and differential scanning calorimetry in order to carefully assess their structural and thermal properties. We demonstrate that telechelic materials can be produced enzymatically at mild temperatures, in a solvent-free system and using renewably sourced monomers without pre-modification, by exploiting the unique properties of scCO 2 . The macromolecules we prepare are ideal green precursors that can be further reacted to prepare useful bio-derived films and coatings.

Synthesis, characterization, application and band gap study of calcium mercaptosuccinate

2017 ◽  
Vol 30 (8) ◽  
pp. 1056-1068 ◽  
Author(s):  
L Kannammal ◽  
S Palanikumar ◽  
B Meenarathi ◽  
R Anbarasan
Keyword(s):  
Band Gap ◽  
Metal Salt ◽  
Research Work ◽  
Gel Permeation Chromatography ◽  
Calcium Content ◽  
Particle Size Analysis ◽  
Size Analysis ◽  
Resonance Spectroscopy ◽  
Scanning Calorimetry ◽  
Experimental Conditions

In the present investigation, a new material was used for the ring-opening polymerization (ROP) of ∊-caprolactone (∊-CL) as a chemical initiator. Generally, the metal salt initiated ROP of ∊-CL yielded a polymer with high melting temperature ( Tm). By keeping this idea in mind, the present research work was carried out. The PCL was synthesized under two different experimental conditions like Monomer to Initiator Ratio ([M/I]) and temperature variation. The optical band gap ( Eg) value for a hybrid was found to be reduced whereas after making composites the same was increased due to the encapsulation effect. The Tm of Poly Caprolactone (PCL) was varied between 68.5°C and 71.4°C. The PCL composites synthesized above were characterized by various analytical tools like Fourier transform infrared spectroscopy, ultraviolet–visible spectroscopy, gel permeation chromatography, differential scanning calorimetry, thermogravimetric analysis, nuclear magnetic resonance spectroscopy (proton and carbon-13), particle size analysis and scanning electron microscopy. The Eg value was increased with the increase in [M/I] ratio due to the decrease in calcium content.

scholarly journals Synthesis of Highly Thermally Stable Daidzein-Based Main-Chain-Type Benzoxazine Resins

Polymers ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1341 ◽  
Author(s):  
Mengchao Han ◽  
Sijia You ◽  
Yuting Wang ◽  
Kan Zhang ◽  
Shengfu Yang
Keyword(s):  
Thermal Stability ◽  
Main Chain ◽  
Gel Permeation Chromatography ◽  
Polymerization Process ◽  
Resonance Spectroscopy ◽  
Scanning Calorimetry ◽  
Molecular Weights ◽  
Potential Applications ◽  
Ft Ir ◽  
Chain Type

In recent years, main-chain-type benzoxazine resins have been extensively investigated due to their excellent comprehensive properties for many potential applications. In this work, two new types of main-chain benzoxazine polymers were synthesized from daidzein, aromatic/aliphatic diamine, and paraformaldehyde. Unlike the approaches used synthesizing traditional main-chain-type benzoxazine polymers, the precursors derived from daidzein can undergo a further cross-linking polymerization in addition to the ring-opening polymerization of the oxazine ring. The structures of the new polymers were then studied by 1H nuclear magnetic resonance spectroscopy (NMR) and Fourier-transform infrared spectroscopy (FT-IR), and the molecular weights were determined by using gel permeation chromatography (GPC). We also monitored the polymerization process by differential scanning calorimetry (DSC) and in situ FT-IR. In addition, the thermal stability and flame-retardant properties of the resulting polybenzoxazines were investigated using TGA and microscale combustion calorimeter (MCC). The polybenzoxazines obtained in this study exhibited a very high thermal stability and low flammability, with a Tg value greater than 400 °C, and a heat release capacity (HRC) value lower than 30 J/(g K).

scholarly journals Bio-Based PBT–DLA Copolyester as an Alternative Compatibilizer of PP/PBT Blends

Polymers ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 1421 ◽  
Author(s):  
Ignaczak ◽  
Sobolewski ◽  
El Fray
Keyword(s):  
Gel Permeation Chromatography ◽  
Mechanical Analysis ◽  
Resonance Spectroscopy ◽  
Twin Screw Extrusion ◽  
Scanning Calorimetry ◽  
Butylene Terephthalate ◽  
Screw Extrusion ◽  
Twin Screw ◽  
Static Tensile ◽  
Copolymer Poly

The aim of this work was to assess whether synthesized random copolyester, poly(butylene terephthalate-r-butylene dilinoleate) (PBT–DLA), containing bio-based components, can effectively compatibilize polypropylene/poly(butylene terephthalate) (PP/PBT) blends. For comparison, a commercial petrochemical triblock copolymer, poly(styrene-b-ethylene/butylene-b-styrene) (SEBS) was used. The chemical structure and block distribution of PBT–DLA was determined using nuclear magnetic resonance spectroscopy and gel permeation chromatography. PP/PBT blends with different mass ratios were prepared via twin-screw extrusion with 5 wt% of each compatibilizer. Thermogravimetric analysis, differential scanning calorimetry, and dynamic mechanical analysis were used to assess changes in phase structure of PP/PBT blends. Static tensile testing demonstrated marked improvement in elongation at break, to ~18% and ~21% for PBT–DLA and SEBS, respectively. Importantly, the morphology of PP/PBT blends compatibilized with PBT–DLA copolymer showed that it is able to act as interphase modifier, being preferentially located at the interface. Therefore, we conclude that by using polycondensation and monomers from renewable resources, it is possible to obtain copolymers that efficiently modify blend miscibility, offering an alternative to widely used, rubber-like petrochemical styrene compatibilizers.

scholarly journals Synthesis of Monoacryloxypropyl-POSS-based Hybrid Epoxyacrylate Copolymers and Their Application in Thermally Curable Structural Self-Adhesive Tapes

Polymers ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2058 ◽  
Author(s):  
Agnieszka Kowalczyk ◽  
Krzysztof Kowalczyk ◽  
Konrad Gziut
Keyword(s):  
Gel Permeation Chromatography ◽  
Transition Process ◽  
Chain Structure ◽  
Accelerated Ageing ◽  
Mechanical Resistance ◽  
Scanning Calorimetry ◽  
Dsc Measurements ◽  
Hybrid Copolymers ◽  
Before And After ◽  
Thermal Stability Of

New organic-inorganic hybrid copolymers (EA-POSSs) based on butyl acrylate, glycidyl methacylate, hydroxybutyl acrylate, acryloiloxybenzophenone and acryloxypropyl-heptaisobutyl-POSS (A-POSS) were prepared via free-radical solution polymerization (FRP) and applied as a component of thermally curable structural self-adhesive tapes (SATs). The EA-POSS with 0.25, 0.5 or 1 mol % of A-POSS exhibited significantly higher dynamic viscosity (ca. +104%), Mw (+61%) and polydispersity (+109%; measured using gel permeation chromatography) as well as lower Tg value (−16 °C) in relation to the A-POSS-free copolymer (EA-0). Differential scanning calorimetry (DSC) measurements (one glass transition process) confirmed statistic chain structure of the EA-POSS materials. Replacement of EA-0 by the EA-POSS copolymers in a SATs recipe caused simultaneous improvement of their self-adhesive features, i.e., adhesion (+70%), tack (+21%) and cohesion (+1590%). Moreover, the POSS-based copolymers improved the shear strength of thermally cured Al/SAT/Al overlap joints; the best mechanical resistance (before and after accelerated ageing tests) was observed for the sample containing 0.5 mol % of A-POSS (an increment range of 50–294% in relation to the A-POSS-free joints). Thermogravimetric analysis (TGA) revealed markedly improved thermal stability of the A-POSS-based SATs as well.

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