Progress 08/16/23 to 08/15/24
Outputs
Target Audience:The powder coating and forest products industries will be the immediate beneficiaries of this investigation by finding biobased alternatives to current petroleum-based powder coatings. Unlike most commercial thermoset powder coatings that are two-part resins and rely on catalysts for curing, the proposed biobased alternative will be a one-part resin that can greatly simplify the manufacturing process and reduce the production cost. By introducing dynamic covalent chemistry into system, the crosslinked coating material could be repaired once damaged, which will extend the service life of the product. The general public will also benefit from the results, because the proposed biobased coating polymers are environmentally friendly, and emit zero volatile organic compounds (VOCs). In addition, the findings from this project will fill the existing gap between renewable thermosets and their applications for high-volume powder coatings, advance the bioplastics knowledge base and stimulate future developments within the biobased plastic materials industry. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?Three postdocs, one PhD student, and two master student have been trained on this project. One WSU senior student was trained on this project for his senior thesis. An NSF/IUCRC REU student was trained in this project in summer 2021. How have the results been disseminated to communities of interest?
Nothing Reported
What do you plan to do during the next reporting period to accomplish the goals?For the next 12 months, we will systematically investigate the structure-performance relationship between the molecular structure of hyperbranched polyesters or epoxy prepolymers and the properties of the powder coatings. Our goal is to optimize the preparation processes and formulations of powder coatings to achieve overall superior performance. Additionally, we will assess the economic viability of the final coating product. Specifically, the following tasks outlined in the proposal will be carried out. 1. Optimize the formulation and synthesis processes to produce phosphorus-containing hyperbranched polyesters and epoxy prepolymers with controllable structures, facilitating the development of powder coatings with customizable properties. 2. Refine the fundamental performance testing of the powder coatings, focusing on characterizing their stress relaxation behavior and self-healing properties. 3. Evaluate the fire safety performance of the powder coatings and elucidate their underlying mechanisms. 4. Organize the data and prepare 1-2 research papers for publication.
Impacts
What was accomplished under these goals?
Over the past year, we have continued our research on the design and preparation of a novel fire-safe hyperbranched carboxy-terminated polyester and epoxy prepolymer for powder coating applications. This study is primarily divided into two parts: 1) the phosphorus-containing hyperbranched carboxy-terminated polyester cured with resveratrol-derived tri-epoxy for powder coating and 2) the phosphorus-containing hyperbranched epoxy prepolymer cured with bio-based aliphatic dicarboxylic acids for powder coating. To evaluate their suitability for powder coating applications, we investigated the curing behavior and rheological properties of these biobased hyperbranched polyester and epoxy resins, including viscosity and gelation time. The resulting coatings were characterized for hardness, adhesion, solvent resistance, self-healing, and flame retardancy. 1. Hyperbranched carboxy-terminated polyester/resveratrol-derived tri-epoxy 1.1 Preparation and characterization of hyperbranched carboxy-terminated polyester Specifically, the hyperbranched carboxy-terminated polyesters were successfully synthesized through polycondensation using N1,N1,N4,N4-tetrakis(2-hydroxyethyl)terephthalamide (THETA), derived from the aminolysis of waste PET bottles, in conjunction with the 9,10-Dihydro-9-oxa-10-phosphaphenanthren-10-oxide itaconic acid adduct (DOPO-itaconic acid) and succinic acid as monomers. These polyesters exhibited glass transition temperatures (Tg) exceeding 40 °C and acid values ranging from 80 to 130 mg KOH/g. By adjusting the feed ratio, the concentrations of ester groups and free hydroxyl groups within the polymer can be effectively controlled. The presence of excess free hydroxyl groups readily participates in dynamic transesterification, thereby influencing the reaction rate and enabling the regulation of the self-healing behavior of the powder coating. Additionally, the incorporation of DOPO groups significantly enhances the fire safety of the coating. 1.2. Preparation and characterization of resveratrol-derived tri-epoxy The bio-based resveratrol-derived tri-epoxy (REP) was synthesized through the glycidylization reaction of resveratrol with epichlorohydrin. It exhibits an epoxy value of 0.75 mol/100g and a melting point of 73 °C. The rigid structure of REP contributes to the enhancement of the thermal and mechanical properties of the resulting coating. 2. Hyperbranched epoxy prepolymer/bio-based aliphatic dicarboxylic acids Specifically, the hyperbranched epoxy prepolymers were synthesized via a ring-opening reaction between DOPO-itaconic acid and the REP. These epoxy prepolymers demonstrated a glass transition temperature (Tg) exceeding 50 ºC, with an epoxy value ranging from 0.50 to 0.65 mol/100g. By adjusting the feed ratio, the concentration of free epoxy groups within the polymer can be effectively controlled, thereby facilitating the regulation of the curing and self-healing behavior, as well as the mechanical properties and flame retardancy of the powder coating. 3. Preparation of powder coating, investigation of powder coating properties 3.1. The resulting hyperbranched polyester resins or epoxy prepolymers were blended with REP or aliphatic dicarboxylic acids using a twin-screw micro-extruder. These blends were then subjected to ball milling and sieving to produce powders with particle sizes smaller than 60 μm. 3.2. The curing behaviors of the powders were analyzed using differential scanning calorimetry, revealing that, in the absence of a catalyst, the peak curing temperatures ranged from 130 to 200 °C. 3.3. The rheological properties of the powders were characterized to evaluate their leveling properties and to determine the gelation time. 3.4. The powders were uniformly spray-coated onto metal plates using a Statiflux powder gun and were subsequently fully cured according to optimized curing procedures. 4. Characterization of primary coating properties In accordance with the relevant ASTM standards, the scratch hardness and adhesion of the powder coatings were measured at H and 4B-5B, respectively, which is comparable to that of commercial coatings. The coatings exhibit exceptional self-healing capabilities, achieving a repair ratio of 85-90% when subjected to a temperature of 200°C for a duration of 10 minutes. Additionally, the powder coatings displayed self-extinguishing behaviors. In summary, the studies proposed under specific aims 1, 2, and 3 were performed and completed. The novel bio-based fire-safe hyperbranched powder coatings were developed, exhibiting good processability, self-healing, satisfactory hardness, strong adhesion and enhanced flame retardancy.
Publications
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Progress 08/16/22 to 08/15/23
Outputs
Target Audience:The powder coating and forest products industries will be the immediate beneficiaries of this investigation by finding biobased alternatives to current petroleum-based powder coatings. Unlike most commercial thermoset powder coatings that are two-part resins and rely on catalysts for curing, the proposed biobased alternative will be a one-part resin that can greatly simplify the manufacturing process and reduce the production cost. By introducing dynamic covalent chemistry into system, the crosslinked coating material could be repaired once damaged, which will extend the service life of the product. The general public will also benefit from the results, because the proposed biobased coating polymers are environmentally friendly, and emit zero volatile organic compounds (VOCs). In addition, the findings from this project will fill the existing gap between renewable thermosets and their applications for high-volume powder coatings, advance the bioplastics knowledge base and stimulate future developments within the biobased plastic materials industry. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?One postdoc, one PhD student, and one master student were trained on this project. One WSU senior student was trained on this project for his senior thesis. An NSF/IUCRC REU student was trained in this project in summer 2021. How have the results been disseminated to communities of interest?
Nothing Reported
What do you plan to do during the next reporting period to accomplish the goals?We will continue to investigate the vitrimer behaviors of the bio-based powder coatings, including repairability and recyclability. The economic performance of the final coating product will also be evaluated. Specifically, the following tasks listed in the proposal will be performed: 4.1 Preparation and performance of coating. 4.2 Investigation of the self-healing property. 4.3 Investigation of the degradation property. 4.4 TEA analysis.
Impacts
What was accomplished under these goals?
Over the past year, we have continued our study on designing and synthesizing novel biobased prepolymers for powder coating applications. Both linear and branched carboxy-polyester resins were synthesized from renewable feedstocks including isosorbide, succinic acid, dimer acid, and citric acid. Rosin- and eugenol-based tri-epoxies were also synthesized and used as curing agents. To evaluate their suitability for powder coating applications, the curing behavior and rheological properties of these biobased polyester resins, including viscosity and gelation time, were investigated. The resulting coatings' hardness, adhesion, and solvent resistance were characterized. 1. Preparation of bio-based carboxy-polyester resins a. Synthesis and characterization of linear carboxy-polyester resins. Fully bio-based polyesters with glass transition temperatures (Tg) of > 60 ºC and acid numbers in the range of 30-50 mg KOH/g were successfully synthesized from isosorbide and succinic acid via polycondensation reaction. The abundant ester groups in these polyesters' backbones readily participate in dynamic transesterification reactions, contributing to the self-healing properties of the resulting coatings. b. Synthesis and characterization of branched carboxy-polyester resins. To increase the degree of crosslinking and tune the gelation time of the powder coating, trimellitic anhydride or citric acid were introduced into the formulation as branching agents. Additionally, dimer acid was incorporated to enhance the flexibility of the final coating. The resulting resins exhibit Tg values of ~ 55-60 ºC and acid numbers of 30-40 mg KOH/g. 2. Preparation of bio-based tri-epoxy curing agents a. Synthesis and characterization of a rosin-based tri-epoxy. Epoxidized maleopimaric acid (EMPA) with an epoxy value of 0.35 mol/100 g was successfully synthesized using natural rosin as the starting material. The rigid structure of EMPA helps to improve the thermal and mechanical properties of the resulting coating. b. Synthesis and characterization of eugenol-based tri-epoxies. Eugenol-based tri-epoxies were synthesized by reacting the phenol group of eugenol with tri-functional trimesoyl chloride or phosphoryl chloride, followed by the epoxidation of the eugenol double bond. The resulting tri-epoxies, with phosphate ester or trimesate ester moieties, not only enhance the thermal and mechanical properties but also boost the fire resistance of the final coating. 3. Investigation of curing behaviors, rheological properties, and powder coating preparation a. The prepared carboxy-polyester resins were compounded with synthesized tri-epoxy curing agents using a twin-screw micro-extruder, respectively. The resulting blend was then ball-milled and sieved into powders with a size smaller than 60 mm. b. The curing kinetics of the powders were studied by differential scanning calorimetry. Under the catalysis of triphenylphosphine, the peak curing temperatures were controlled to be 130 - 150 ºC. c. The rheological properties of the powders were characterized to assess their leveling properties and determine the gelation time. d. The powders were uniformly spray-coated onto metal plates using a statiflux powder gun and subsequently fully cured following optimized curing procedures. 4. Characterization of primary coating properties Following the corresponding ASTM standards, the scratch hardness and adhesion of the powder coatings were determined to be H and 4B-5B, respectively, comparable to commercial coatings. 5. Development of a fully bio-based UV-curable powder coating system UV-curable prepolymers were synthesized from bio-based feedstocks, and their curing kinetics as well as processabilities (viscosity and gel time) were evaluated. In summary, the studies proposed under specific aims 1, 2, and 3 were performed and completed. Bio-based carboxy-polyester powder coatings were developed, exhibiting good processability, a high Tg value, satisfactory hardness, and strong adhesion. Meanwhile, fully bio-based UV-curable prepolymers with good processability and a high Tg value were also prepared.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2022
Citation:
Baoming Zhao, Cheng Hao, Yu-Chung Chang, Yiding Cao, Tuan Liu, Mingen Fei, Lin Shao, Jinwen Zhang*. Photo-curing 3D Printing of Thermosetting Sacrificial Tooling for Fabricating Fiber-Reinforced Hollow Composites, Advanced Functional Materials, 2023, DOI: 10.1002/adfm.202213663.
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Progress 08/16/21 to 08/15/22
Outputs
Target Audience:The powder coating and forest products industries will be the immediate beneficiaries of this investigation by finding biobased alternatives to current petroleum-based powder coatings. Unlike most commercial thermoset powder coatings that are two-part resins and rely on catalysts for curing, the proposed biobased alternative will be a one-part resin that can greatly simplify the manufacturing process and reduce the production cost. By introducing dynamic covalent chemistry into system, the crosslinked coating material could be repaired once damaged, which will extend the service life of the product. The general public will also benefit from the results, because the proposed biobased coating polymers are environmentally friendly, and emit zero volatile organic compounds (VOCs). In addition, the findings from this project will fill the existing gap between renewable thermosets and their applications for high-volume powder coatings, advance the bioplastics knowledge base and stimulate future developments within the biobased plastic materials industry. Changes/Problems:Due to COVID 19, some students left WSU earlier than expected so we are behind schedule. This project will need to continue into year 2024 to complete all studies and project goals.? What opportunities for training and professional development has the project provided?One postdoc, one PhD student, and one master student were trained on this project. One WSU senior undergraduatestudent was trained on this project for his senior thesis. How have the results been disseminated to communities of interest?
Nothing Reported
What do you plan to do during the next reporting period to accomplish the goals?We will continue to investigate the rheological properties and vitrimer behaviors of the crosslinked HBEPs. The thermomechanical properties, repairability will be studied.Specifically, the following tasks listed in the proposal will be performed: 3.1 Rheological properties. 3.2 Self-healing and welding. 4.1 Preparation and performance of coating.
Impacts
What was accomplished under these goals?
Over the past year, we have continued our study on the synthesis of biobased monomers and hyperbranched epoxy polymers (HBEPs). Hemp seed oil-derived triepoxy (A3 monomer) and rosin-based diiacid (B2 monomer) were synthesized and used to prepare biobased HBEPs. The ratio of flexible A3 monomer to rigid B2 monomer was varied to tune the thermal properties of HBEPs and the resulting coatings. A fully biobased UV curable powder coating resin was also developed and evaluated. 1. Monomer synthesis a. Synthesis and characterization of hemp seed oil-based glycidyl ester-type triepoxy (HOEP) as A3 monomer. The ester groups in HOEP are beneficial to the dynamic transesterification reaction and the self-healing properties of the resulting coatings. b. Synthesis and characterization of natural rosin-derived acrylic pimaric acid (APA) as B2 monomer. The rigid structure of APA helps to improve the thermomechanical properties of the final coating product. 2. HBEP synthesis a. Investigation of the effect of HOEP/APA ratio on melting temperatures of HBEPs. HBEPs that meet the processability requirement (viscosity less than 1Pa·s at 110 - 150 ºC; gel time from 10 to 20 min at 110 - 150 ºC) for powder coating were selected for further investigation. b. Investigation of the curing kinetics. The necessary curing time to achieve a complete cure was determined at the peak curing temperature (~ 150 ºC) c. Investigation of the effect of HOEP/APA ratio on Tg of the cured polymers. Cured coatings that exhibit a Tg of > 50 ºC were selected and will be used for performance evaluation. 3. Development of a fully biobased UV curable powder coating system a. Synthesis and characterization of UV curable prepolymers from biobased feedstocks. Fully biobased UV curable polyesters were prepared. b. Investigation of the effect of reaction conditions on melting temperatures, molecular weight, and Tg of the prepolymers. Reaction conditions that yield polyesters with a melting temperature of 130 ºC and a Tg of 65 ºC were identified. c. Investigation of the processability (viscosity and gel time) of the prepolymers. Polyesters with a gel time of 20 min at 170 ºC were selected for further evaluation. In summary, the studies proposed under specific aims 1 and 2 (synthesis of biobased HBEPs, investigation of the self-crosslinking behavior of HBEP) were performed and completed. HBEPs with satisfactory melting point, viscosity, gel time and Tg value were identified and will be used for further investigation. The meantime, fully biobased UV curable powder coating with good processability, low melting temperature and high Tg value was also prepared.
Publications
- Type:
Conference Papers and Presentations
Status:
Accepted
Year Published:
2022
Citation:
presented at ACS Fall 2022 and ASTM International Conference on Additive Manufacturing 2022
- Type:
Journal Articles
Status:
Under Review
Year Published:
2023
Citation:
The findings from the development of UV-curable powder coating system promote the development of recyclable reins for photocuring 3D printing. The results were submitted for publication in peer-reviewed journal Composites Part B: Engineering (currently under review)
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Progress 08/16/20 to 08/15/21
Outputs
Target Audience:The powder coating and forest products industries will be the immediate beneficiaries of this investigation by finding biobased alternatives to current petroleum-based powder coatings. Unlike most commercial thermoset powder coatings that are two-part resins and rely on catalysts for curing, the proposed biobased alternative will be a one-part resin that can greatly simplify the manufacturing process and reduce the production cost. By introducing dynamic covalent chemistry into system, the crosslinked coating material could be repaired once damaged, which will extend the service life of the product. The general public will also benefit from the results, because the proposed biobased coating polymers are environmentally friendly, and emit zero volatile organic compounds (VOCs). In addition, the findings from this project will fill the existing gap between renewable thermosets and their applications for high-volume powder coatings, advance the bioplastics knowledge base and stimulate future developments within the biobased plastic materials industry. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?An NSF/IUCRC REU student was trained in this project in summer 2021. How have the results been disseminated to communities of interest?
Nothing Reported
What do you plan to do during the next reporting period to accomplish the goals?We will continue to investigate the synthesis of biobased HBEPs, the self-crosslinking behavior of the HBEPs, the rheological properties and vitrimer behavior of the crosslinked HBEPs, and the performance of the HBEP powder coatings. Specifically, the following Tasks will be performed: 1.2 HBEP synthesis. 1.3 Lysine regulated HBEP structure for accelerated curing and dynamic transesterification. 1.4 Characterizations of HBEPs. 2.1 Investigation of the precessability of the polymers. 2.2 Investigation of curing kinetics. 3.1 Rheological properties. 3.2 Self-healing and welding.
Impacts
What was accomplished under these goals?
In the past year, we have focused our study on synthesis of biobased diepoxies (A2 monomers), triepoxies (A3 monomers), and triacids (B3 monomers). These monomers were subsequently used to synthesize biobased hyperbranched epoxy polymers (HBEPs). The effects of reaction temperature and reaction time on chemical structure and physical properties of HBEPs were investigated. A fully biobased UV curable powder coating was also synthesized and the processability of the polymers were investigated. 1. Monomer synthesis a. Synthesis and characterization of biobased diepoxies from isosorbide b. Synthesis and characterization of biobased triepoxies based on natural rosin c. Synthesis and characterization of biobased triepoxies from citric acid d. Synthesis and characterization of biobased triacids based on natural rosin 2. HBEP synthesis a. Effects of reaction conditions on molecular weight distribution of the polymers b. Effects of reaction conditions on viscosity and Tg of the polymers 3. Synthesis of fully biobased UV curable powder coating a. Effects of reaction conditions on viscosity and Tg of the polymers b. Investigation of the processability of the polymers
Publications
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