Progress 07/01/17 to 02/28/19
Outputs
Target Audience:Paper companies and manufacturers that produce cardboard and paper packaging. Companies that deal with special additives and coatings for paper processing, so-called "paper sizing agents". Paper packaging and specialty paper manufacturers that use surface sizing agents to improve paper barrier properties, such as water and grease resistance, and water vapor and gas transmission. The Renuvix team put together a white paper "Nanocomposite Binder Systems for Dispersion Coatings That Enable Biodegradable, Paper-Based Packaging with Enhanced Barrier Properties" and shared non-confidential results of the Phase I project with companies that expressed interest in the new binder systems. Changes/Problems:One of the challenges that the Renuvix team faced when working on the Copolymer modificationtask was dramatically different solubility behavior of copolymers based on conventional and hydrogenated soybean oil - poly(CsoyVE-alt-MA) and poly(HsoyVE-alt-MA). The last one due to the crystalline nature of saturated fatty chains was not able to produce stable aqueous dispersions under our testing conditions. So, our focus was shifted to poly(CsoyVE-alt-MA) dispersions and expanded to include more neutralization agents such as pH-controlamines.Dispersions of poly(HsoyVE-alt-MA) product were excluded from the study. Another challenge was to incorporate cellulose nanomaterials in the nano-composite systems. The team chose to blend cellulose nanomaterials using high-speed disperser, which was sufficient to provide uniform dispersions for both cellulose nanofibers (CNFs) and cellulose nanocrystals (CNCs). However, polymer dispersions blended with highly crystalline CNCs resulted in formulations with low stability that had a tendency to phase separation. Also, coatings produced from CNC-loaded formulations had much higher roughness due to the presence of CNC agglomerates. So, our team chose to move forward with testing only CNFs as a cellulose nanomaterial, and CNCs were excluded from the study. Biodegradability and air-permeability testing for papers coated with poly(CsoyVE-alt-MA) coating were not conducted since our contact at testing organization left. The team approached other testing organizations to complete the testing, but could not schedule the testing within the timeframe of the project. Testing is planned in the Phase II project. What opportunities for training and professional development has the project provided?
Nothing Reported
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?
Nothing Reported
Impacts
What was accomplished under these goals?
The Renuvix team has successfully developed a binder system for dispersion barrier coatings based on Renuvixplant-oil vinyl ether copolymers and a cellulose nanomaterial. The synthesis of plant-oil vinyl ether monomerwas scaled up to the 10 L size reactor, and copolymers were produced at the 2.5 L scale. Bothconventional soybean oil and hydrogenated soybean oil were used to produce copolymers with maleic anhydride -poly(CsoyVE-alt-MA)and poly(HsoyVE-alt-MA) respectively. Synthesized copolymers were modified to make carboxylated derivatives and provide water dispersibility/solubility. First, the modification was carried out through the anhydride ring-opening reaction with waterat the end of the polymerization process. Over 50% ring-opening was achieved after 3h of hydrolysiswhich provided sufficient amount of carboxylic groups to formulate stable aqueous dispersions and colloidal solutions of the copolymer.Three different bases were evaluated for formulating stable aqueous dispersions of these copolymers - ammonia hydroxide (AH),primary organic amine (PA), and tertiary organic amine(TA). Various ratios of each base to carboxylated copolymer were tested to determine the minimum amount of base needed to provide stable aqueous dispersions.Our studies show that water dispersibility/solubility was easily achieved forpoly(CsoyVE-alt-MA) resins, however, aqueous dispersions ofpoly(HsoyVE-alt-MA) showed dramatically low stability, which was linked to the high crystallinity of hydrogenated soy fragments. A minimum of 40% neutralization was required to provide stable colloidal dispersions of poly(CsoyVE-alt-MA) for bases. Amine neutralized copolymers have shown better water dispersibility and stability in comparison to copolymer neutralized with ammonia. The addition of different levels of neutralizing bases allows for the control of formulation viscosityfrom6 cP to 1300 cP, pH value in the range of 5.5 to 10, and a range of polymer solubility/dispersibility. Modified (carboxylate functional) copolymers in the form of aqueous dispersions were applied on paper to evaluate their ability to provide barrier properties. Coated papers were cured in the oven with and without driers to assess the extent of curing and changes in surface properties. Papers coated with copolymer dispersions were tested for water absorption, grease resistance, and surface wettability. We found that dispersion coatings based on poly(CsoyVE-alt-MA) make better films when cured in the presence of driers. Thus, the addition of as little as 0.08% drying catalyst has dramatically increased film curing and improved coating barrier performance. Our extraction studies showed that more than 98% of the polymer was non-extractable, indicating great integration of new binder resin in the coating. Surface spectroscopy studies show noticeable changesin the paper surface with a significant level of soy coating attached. We found that papers coated with poly(CsoyVE-alt-MA)copolymers show barrier properties 4 to 5 times better than the uncoated paper. Aqueous solutions/dispersions of poly(CsoyVE-alt-MA)copolymers were used to produce colloidal dispersions with cellulose-nanomaterials (CNMs). Two different CNMs were evaluated - cellulose nanocrystals (CNCs) and cellulose nanofibers (CNFs). Our studies showed that CNFs can be easily blended in the dispersions ofpoly(CsoyVE-alt-MA)copolymers at levels from 1 to 10% wt (of CNF suspension) in order to achieve colloidal dispersion with applicable viscosity. In these systems, the level of CNF is the major factor contributing to the viscosity which can be controlled in the rangefrom 20 cP to 2000 cP. CNCs were blended with poly(CsoyVE-alt-MA) dispersions in a similar way,however, such combination resulted in muchlower dispersion stability. Even at the lowest CNC loads tested (1-2 % of CNC suspension), the colloidal dispersion provided non-uniform coatings with the rough surface due to inclusions of CNC agglomerates. In regard to the nature of the neutralizing base, it was found that viscosity of the colloidal dispersion increases in the following order: TA- neutralized, PA- neutralized, AH- neutralized copolymer. The barrier properties of the paper coated with new binder systems based on dispersions of poly(CsoyVE-alt-MA) neutralized with different bases and blended with CNFswere evaluated by industry standardmethods. Water absorption was determined byTAPPI method T558, water vapor transmission rate by TAPPI T448, the grease resistance by TAPPI T559 and water wettability by water contact angle measurements. These studies provided us with information on the performance of formulations with neutralization levels in the wide range of base to carboxylic acid ratios. It was found that wettability of the coated papers with water changes with the nature and level of neutralizing base. Thus, dispersions of poly(CsoyVE-alt-MA) neutralized with AH resulted in higher water contact angles if compared to PA and TA - neutralized formulations. Formulations containing polymer neutralized with PA consistently showed the highest water absorption. Also, a slight increasing trend in water absorption was found with increased CNF loading. Grease resistance showed a slightly decreasing trend with increasing CNF loading and very little difference amongst the neutralizing bases. The water vapor transmission testing showed no distinct trends with changing CNF loading or nature and level of neutralizing base. Kaolin platey filler was added to the best performing aqueous dispersions ofpoly(CsoyVE-alt-MA) copolymer and CNFs to evaluate the ability to produce stable dispersion coatings. For this study, two commercial styrene-based dispersions were used as references. Viscosity studies showed that kaolin loaded dispersions showed comparable viscosities for most formulations except those produced from AH-neutralized copolymer. However, PA- and TA- based kaolin loaded dispersions had viscosities in range 100-230 cP which was comparable to commercial dispersions with the same level of loaded kaolin filler. Evaluation of barrier properties of paper coated with kaolin filled dispersions has demonstrated feasibility of novel nanocomposite binder system for dispersion barrier coatings. Based on the results of our testing, styrene-based dispersion coatings absorbed more water than any of Renuvix dispersion coatings. Also, kaolin-filled paper coatings based onpoly(CsoyVE-alt-MA) copolymer dispersions displayed slightly higher water contact angles if compared to coatings based on commercial dispersions, thus indicating more hydrophobic and water-repellant nature of the coating. All kaolin-filled Renuvix and commercial papercoatings tested showed similar grease resistance.
Publications
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Progress 07/01/17 to 06/30/18
Outputs
Target Audience:The successful development and commercialization of high-performance, biodegradable packaging based on the proposed approach will have substantial benefits to the packaging industry. Global paper companies and plants that make cardboard packaging, as well as businesses supplying large and small paper packaging around the world, and industries that have moved into diverse plastic coatings for paper are our primary customer segments. Also new biodegradable coatings for paper packaging will benefit industrial segments that are focused on environmentally friendly packaging technologies and paper coatings with lower carbon foot prints compared to petrochemical materials. Changes/Problems:Our attempts to produce stable water-dispersible materials from semi-crystalline carboxylated copolymers based on hydrogenated soybean oil have not been successful so far. Even high neutralization degrees did not provide stable aqueous dispersions. From the standpoint of production and potential commercialization, hydrogenated soybean oil-based copolymers are more attractive, as the copolymerization process is simpler and can be performed at higher solids. They are also not susceptible to autoxidation which may be beneficial for the resin shelf-life. Our team is still researching options for modification to produce stable water-dispersible derivatives from semi-crystalline carboxylated copolymers based on hydrogenated soybean oil. We expanded the range of neutralizing bases to help tailor barrier properties and shelf life of the new copolymers. What opportunities for training and professional development has the project provided?
Nothing Reported
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? To determine the biodegradability of paper coated with the copolymers based on conventional soybean oil. To include water vapor permeability data to support barrier property studies on paper coated with the new copolymers. To produce dispersion coatings by blending stable aqueous dispersions of the copolymer, a cellulose nanomaterial (CNM), and a platey filler. To determine the barrier properties of select coatings containing soybean oil-based copolymer, CNM, and a platey filler.
Impacts
What was accomplished under these goals?
Our team has successfully synthesized fatty monomers based on conventional soybean oil and hydrogenated soybean oil, studied polymerization kinetics, optimized the process, and scaled it up to the 10L size reactor. Synthesized copolymers were modified to make carboxylated derivatives and provide water dispersibility/solubility. Three different bases were evaluated for formulating stable aqueous dispersions of these copolymers. All bases require minimum 40% neutralization to provide stable colloidal dispersions for modified formulations. Amine neutralized copolymers have shown better water dispersibility and stability in comparison to copolymer neutralized with ammonia. The addition of different levels of neutralizing bases allows for the control of formulation viscosity from as low as 6 cP to 1300 cP, pH in the range of 5.5 to 10, and a range of polymer solubility/dispersibility. Modified copolymers in the form of aqueous dispersions were applied on paper to evaluate their ability to provide barrier properties. Coated papers were cured at elevated temperatures with and without driers to assess the extent of curing and changes in surface properties. Papers coated with copolymer dispersions were tested for water absorption, grease resistance, and surface wettability. We found that coating papers with our water-dispersed copolymers improve paper barrier properties 4 to 5 times over the uncoated paper.
Publications
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