Progress 11/18/13 to 10/31/18
Outputs
Target Audience:The findings of this research have been shared with three packaging companies interested in improving the shelf life of foods. Also, they have been disseminated to the broader scientific community through publications in scientific journals and presentations at national and/or international annual conferences on biomaterials so that they are available to farmers, companies, public, and scientific community interested in sustainable biomaterials from plants. The information gathered during this research is also being incorporated into a graduate course on materials taught at MSU. They are used as examples in a course taught by Dr. Matuana at MSU (PKG 825-Polymeric Packaging Materials) and other universities. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?This research project provided training and/or professional development to the following individuals at Michigan State University: Dr. Cheng Xing, a postdoctoral fellow; three graduate students [Ms. Sonal Karkhanis (Ph.D.), Ms. Mamata Tathe (MS level), and Ms. Yuzhu Liu (MS level)] as well as the following eleven undergraduate students: Ms. Kristi Hughes, Ms. Lauren Ryder, Mr. Jason Schon, Mr. Cameron Friesen, Ms. Anna Marra, Ms.Marie Yaccarino, Ms. Lauren Chard, Ms. Allison Friebe, Ms. Victoria Jansz, Ms. Hannah Brubaker, and Ms.Haley Ferer. How have the results been disseminated to communities of interest?The results of this research project are used as tutorial examples in the classes taught at MSU by Dr. Matuana (e.g., PKG 323 Packaging with Plastics and PKG 825 Polymeric Packaging Materials). They have also been disseminated through publications to peer reviewed journals, the World Wide Web, and presentations at the national and/or international annual conferences on composites. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
We overcome the brittleness of PLA through plasticization with bio-oil additive. PLA was successfully plasticized with epoxidized soybean oil (ESO). The impact strength and the ductility of plasticized sheets increased significantly with the ESO content; and the brittle-to-ductile transition occurred in the range of 5-10 wt% ESO content. This toughening capacity of ESO as a plasticizer was attributed to its partial miscibility with the matrix. In contrast, both the tensile strength and the modulus of the sheets decreased with increasing ESO content due to the plasticization effect, which induced a decrease in the glass transition temperature. Additionally, the plasticization of PLA film with ESO did not affect its heat sealability during flexible pouch manufacturing as indicated by the burst pressure and the seal strength, which remained unaffected by the addition of plasticizer, irrespective of the sealing temperature studied. Although we have successfully overcome the brittleness drawback and have developed a means to plasticize PLA with ESO, a biobased oil, in order to enhance the materials flexibility, the permanency of the plasticizer in the film remained one of the concerns. Two problems could arise if the plasticizer leaches out from the film: (1) The film will lose its flexibility and (2) the oil (ESO) could migrate and potentially contaminate the packaged product. We assessed the permanency of ESO in the plasticized film. The effect of storage on the performance of ESO plasticized PLA films manufactured through a cast extrusion process was investigated. Films plasticized with 10 wt% ESO were stored in a desiccator at room temperature and the melt viscosity, thermal, and tensile properties were measured over a minimum of 90 days of storage. Additionally, infrared spectroscopy monitored plasticizer migration to the surface of plasticized film. Plasticizer migration occurred within the first 30 days of storage, which significantly affected the properties of plasticized films. While the melt viscosity, glass transition temperature, degree of crystallinity, tensile strength and modulus increased, the elongation at break and energy to break in contrast decreased with the storage time up to around 30 days and all properties remained constant thereafter suggesting that the films lost some flexibility during storage. However, the ability of stored plasticized film to cold crystallize was unaffected since both the cold crystallization temperature and melting temperature were not affected during storage. Although the storage time led to property changes, plasticized PLA films still remained more flexible than the unplasticized counterpart even after 90 days storage. This result indicated that sufficient plasticization performance still remained in ESO-plasticized PLA films for flexible packaging application even after a long storage period at ambient conditions. Another objective of this project was to use cellulose nanocrystals (CNCs) as additive to improve the water and gas barrier properties of PLA films for food packaging. However, before incorporating cellulose nanomaterials into PLA, it was paramount to overcome the difficulty of production PLA films through melt processing techniques such as extrusion blown and/or cast films due to its insufficient melt strength. Processing strategies were developed to manufacture blown PLA films without melt strength enhancers. We examined the effects of various processing conditions and material parameters on the melt rheology, thermal property, and blow up ratios of the films. Experimental results indicated that the extrusion-blown PLA films could be successfully made without melt strength enhancers. Irrespective of the degree of crystallinity, stable PLA films with a blow-up ratio of 5 were achieved by controlling the melt rheology through processing conditions such as the temperature, film take up ratio, internal pressure, and external cooling air pressure. Successful production of PLA films led to a study aimedat identifying the best approach of incorporating cellulose nanocrystals (CNCs) into a poly(lactic acid) (PLA) matrix by examining two different CNC addition approaches. The first approach consisted of melt-blending PLA and CNCs in a three-piece internal mixer whereas the second method involved direct dry-mixing of PLA and CNCs in a high intensity mixer. The compounded materials were then blown into films and compared in terms of fiber dispersion, optical, thermal, molecular weight and barrier properties. Good distribution was achieved by both the direct dry- and melt-blending methods. However, some agglomerations were still present that resulted in reduced transparency of the composite films. Furthermore, the PLA/CNC films thermally degraded during the blending processes indicated by the drop in their molecular weights due to chain scissions. More chain scissions occurred in melt-blended films than the dry-blended counterparts. The addition of only 1% CNCs into the PLA matrix by the direct dry- and melt-blending approaches improved the water barrier properties of PLA films by 30% and 24%, respectively. The inferior performance of the melt-blended films compared to the direct dry-blended counterparts could be attributed to more chain scissions in these films. Thus, the direct dry-blending process appeared to be the better approach of incorporating CNCs into the PLA matrix. In a following study, the effect of CNC content on the water vapor (WVP) and oxygen (OP) barrier properties of blown PLA films was evaluated at various temperatures and relative humidities. The following conclusions were drawn: (1) Both WVP and OP of PLA and PLA/CNC nanocomposite films varied exponentially with temperature as expected from the Arrhenius equation, whereas the WVP remained constant with relative humidity as expected from Fick's law. (2) The nanocomposite films were better barriers to both water and oxygen compared to PLA films irrespective of the testing temperature and relative humidity, attributable to the presence of highly crystalline CNCs, which increased the degree of crystallinity of the nanocomposites and acted as impermeable regions in the matrix, thus creating a tortuosity effect. (3) The values of WVP and OP negatively correlated with the degree of crystallinity, i.e., as the crystallinity increased the WVP and OP decreased. In fact, depending on testing temperature or humidity, optimum improvements in WVP (30-40%) and OP (65-75%) of PLA films occurred at 1% CNCs, a CNC content that correlated very well with the maximum increase in crystallinity. (4) The combined effects of increased crystallinity and CNC agglomerations negatively affected the light transmission of nanocomposite films by scattering light without affecting their visual clarity. (v) The transparent blown PLA/CNC nanocomposite films with better barrier performance developed in this study have tremendous potential for food packaging applications. The effectiveness of PLA/CNC film in extending the shelf life of crackers, a water sensitive food, was also studied. Crackers packaged in CNC-based films were shelf stable when stored a room temperature and at approximately 68% relative humidity (RH) whereas the crackers packaged in control film (neat PLA) reached the critical moisture content of 8% after only 15 hours under the same storage conditions. In addition, CNC-based packages had three times longer shelf life at 99% RH than the neat PLA package. These results clearly demonstrate that PLA/CNC films are effective in extending dry foods' shelf life compared to neat PLA films.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2018
Citation:
S.S. Karkhanis, N.M. Stark, R.C. Sabo, and L.M. Matuana, Water Vapor and Oxygen Barrier Properties of Extrusion-Blown Poly(lactic acid)/Cellulose Nanocrystals Nanocomposite Films, Composites Part A: Applied Science and Manufacturing, 114: 204-211 (2018). doi.org/10.1016/j.compositesa.2018.08.025.
- Type:
Journal Articles
Status:
Published
Year Published:
2017
Citation:
S.S. Karkhanis, N.M. Stark, R.C. Sabo, and L.M. Matuana, Performance of Poly(Lactic Acid)/Cellulose Nanocrystal Composite Blown Films Processed by two Different Compounding Approaches, Polymer Engineering and Science, Published online Dec. 18, 2017. doi: 10.1002/pen.24806.
- Type:
Journal Articles
Status:
Published
Year Published:
2017
Citation:
S.S. Karkhanis, N.M. Stark, R.C. Sabo, and L.M. Matuana, Blown Film Extrusion of Poly(Lactic Acid) Without Melt Strength Enhancers, Journal of Applied Polymer Science, 134 (34): article 45212 (10 pages). (2017). doi: 10.1002/app.45212
- Type:
Journal Articles
Status:
Published
Year Published:
2016
Citation:
C. Xing and L.M. Matuana, Epoxidized Soybean Oil-Plasticized Poly(Lactic Acid) Films Performance as Impacted by Storage, Journal of Applied Polymer Science, 133 (12): 43201 (8 pages) (2016). doi: 10.1002/app.43201
- Type:
Journal Articles
Status:
Published
Year Published:
2014
Citation:
S. Vijayarajan, S.E.M. Selke, and L.M. Matuana, Continuous Blending Approach in the Manufacture of Epoxidized Soybean-Plasticized Poly(Lactic Acid) Sheets and Films, submitted to Macromolecular Materials and Engineering, 299 (5): 622-630 (2014). doi: 10.1002/mame.201300226
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2017
Citation:
S.S. Karkhanis, L.M. Matuana, N.M. Stark, R.C. Sabo, Effect of Compounding Approaches on Fiber Dispersion and Performance of Poly (Lactic Acid)/Cellulose Nanocrystal Composite Films, in Proceedings, ANTEC, Annual Technical Conference, Society of Plastics Engineers, May 8-10, 2017, Anaheim, CA.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2017
Citation:
L.M. Matuana, S.S. Karkhanis, N.M. Stark, and R.C. Sabo, Barrier Properties of Sustainable Bio-Plastic Films Filled with Cellulose Nanocrystals, at the 2017 Advancements in Fiber-Polymer Composites Symposium, Madison, WI, May 16-18, 2017.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2016
Citation:
L.M. Matuana, S.S. Karkhanis, N.M. Stark, and R.C. Sabo, Cellulose Nanocrystals as Barrier Performance Enhancers of Extrusion-Blown PLA Films for Food Applications, the 10th Annual TechConnect World Innovation Conferences and Expo, co-located with the National Innovation Summit, National SBIR/STTR Conference and the 18th annual Nanotech Conference, Washington D.C., United States, 22-25 May, 2016. (Presented Tuesday May 24, 2016)
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2016
Citation:
L.M. Matuana, S.S. Karkhanis, and N.M. Stark, Strategies to Manufacture Extrusion-Blown PLA films without Melt Strength Enhancers, The 14th International Symposium on Bioplastics, Biocomposites & Biorefining: Sustainable Bioeconomy to Marketplace. Guelph, Ontario, Canada, May 31 to June 03, 2016. (Presented May 31, 2016)
- Type:
Journal Articles
Status:
Published
Year Published:
2016
Citation:
L.M. Matuana, S.S. Karkhanis, N.M. Stark, and R.C. Sabo, Cellulose Nanocrystals as Barrier Performance Enhancers of Extrusion-Blown PLA Films for Food Applications, In Biotech, Biomaterials and Biomedical - TechConnect Briefs, 3: 1-4 (2016). ISBN 9780997511727 (Publisher: TechConnect)
- Type:
Theses/Dissertations
Status:
Published
Year Published:
2016
Citation:
Sonal Sanjay Karkhanis, Strategies To Manufacture Poly(Lactic Acid) Blown Films Without Melt Strength Enhancers, Packaging - Master of Science Thesis, Michigan State University (2016), 105 pages.
- Type:
Other
Status:
Under Review
Year Published:
2018
Citation:
L.M. Matuana, S.S. Karkhanis, N.M. Stark, and R.C. Sabo, Potential of PLA/CNC Films for Improving the Self Life of a Dry Food Product, MSU Invention Disclosure Case Number TEC2018-0131, April 6, 2018.
- Type:
Other
Status:
Under Review
Year Published:
2017
Citation:
L.M. Matuana, S.S. Karkhanis, N.M. Stark, and R.C. Sabo, Extrusion-Blown PLA Films Without Melt Strength Enhancers and Their Composites With Cellulose Nanomaterials, MSU Invention Disclosure Case Number TEC2018-0063, filed October 31, 2017.
|
Progress 10/01/16 to 09/30/17
Outputs
Target Audience:The findings of this research have been shared with couple of packaging companies interested in improving the shelflife of foods. Also, they have beendisseminated to the broader scientific community through publications in scientific journals and presentations at national and/or international annual conferences on biomaterials so that they are available to farmers, companies, public, and scientific community interested in sustainable biomaterials from plants. The information gathered during this researchis also being incorporated into a graduate course on materials taught at MSU. They are used as examples in a course taught by Dr. Matuana at MSU (PKG 825-Polymeric Packaging Materials) and other universities. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?During this reporting period, this research project provided or continues to providetraining and/or professional development to the following individuals at Michigan State University: two graduate students [Ms. Sonal Karkhanis (Ph.D.) and Ms. Yuzhu Liu (MS level)] as well as the following undergraduate students: Ms. Lauren Chard, Ms. Allison Friebe, Ms. Hannah Brubaker, and Ms. Ms. Haley Ferer. How have the results been disseminated to communities of interest? Peer reviewed journal publication and conference meetings. P3Nano-US Endowment for Forestry and Communities Annual Meeting held at USDA Forest Service, Forest Products Laboratory in Madison, WI. What do you plan to do during the next reporting period to accomplish the goals?The goals to be accomplished during the next reporting period include: (i) evaluation of mechanical properties (tensile and dart impact) and other physical properties [water and gas barrier properties as function of temperature and relative humidity, refractive index, morphology (FE-SEM) and surface roughness (AFM)] of extrusion-blown PLA/CNC composites films; (ii) preliminary study on the manufacture of PLA/CNC composites films using cast extrusion process and their property evaluation; and (iii) preliminary study on the effectiveness of PLA/CNC composite films to extend food shelf life.
Impacts
What was accomplished under these goals?
Cellulose nanocrystals (CNCs) are renewable and sustainable filler for polymeric nanocomposites. However, its high hydrophilicity limits their use with hydrophobic polymer for composite materials. In other terms, one of the limitations for CNCs as reinforcement in polymer matrix is that CNCs tend to aggregate during drying process due to high surface area and surface energy. Nanocomposites from CNCs and hydrophobic polymers have been mostly prepared by organic solvent cast to attain a reasonable dispersion of CNCs in the polymer matrix. Nevertheless, melt-processing is the more applicable, scalable and commercial technique for manufacturing polymer composites, but there are some challenges for surface interaction between polymers and CNCs. Three studies were performed during this reporting period to develop approaches to improving the dispersion of CNCs into the polymer matrix. The first study was aimed to identify the best approach of incorporating cellulose nanocrystals (CNCs) into a poly(lactic acid) (PLA) matrix by examining two different CNC addition approaches. The first approach consisted of melt-blending PLA and CNCs in a three-piece internal mixer whereas the second method involved direct dry-mixing of PLA and CNCs in a high intensity mixer. The compounded materials were then blown into films and compared in terms of fiber dispersion, optical, thermal, molecular weight and barrier properties. Good distribution was achieved by both the direct dry- and melt-blending methods. However, some agglomerations were still present that resulted in reduced transparency of the composite films. Furthermore, the PLA/CNC films thermally degraded during the blending processes indicated by the drop in their molecular weights due to chain scissions. More chain scissions occurred in melt-blended films than the dry-blended counterparts. The addition of only 1% CNCs into the PLA matrix by the direct dry- and melt-blending approaches improved the water barrier properties of PLA films by 30% and 24%, respectively. The inferior performance of the melt-blended films compared to the direct dry-blended counterparts could be attributed to more chain scissions in these films. Thus, the direct dry-blending process appeared to be the better approach of incorporating CNCs into the PLA matrix. In the second study, CNCs were chemically functionalized by transesterification with canola oil fatty acid methyl ester (CME) to enhance CNC dispersion into the polymer matrix. CME performed as both the reaction reagent and solvent. Transesterified CNC (CNCFE) was characterized for their chemical structure, morphology, crystalline structure, thermal stability, and hydrophobicity. Analysis by Fourier transforminfrared (FTIR) and FT-Raman spectroscopies showed that the long chain hydrocarbon structure was successfully grafted onto CNC surfaces. After transesterification the crystal size and crystallinity of nanocrystals were not changed as determined by Raman spectroscopy and wide angle X-ray diffraction (XRD). CNCFE showed higher thermal stability and smaller particle size than unmodified CNCs. Water contact angle measurement indicated the CNCFE surface has significantly higher hydrophobicity than unmodified CNCs. The transesterified CNCs could be potentially used as hydrophobic coatings and reinforcing agents to hydrophobic polymer for nanocomposites. In the third study, the transesterified CNCs (CNCFE) were compounded with PLA into nanocomposites. CNCFE with long chain hydrocarbons plays a role as plasticizer. Increasing CNCFE loadings resulted in clear plasticizing effects. Lower glass transition temperature (Tg) and the melting temperature (Tm) were achieved for CNCFE-based nanocomposites. By plasticizing nanocomposites melt with CNCFE, this can mitigate the degradation of CNCs during thermal processing. The elongation at break of nanocomposites containing 5 % CNCFE was increased. Dynamic rheological study showed the highest elastic and viscous moduli (G′ and G′′) and complex viscosity (G*) of nanocomposites with addition of 2 % CNCFE. By tailoring the loadings of the transesterified CNCs, tunable structure and properties of nanocomposites can be obtained.
Publications
- Type:
Journal Articles
Status:
Submitted
Year Published:
2017
Citation:
L. Wei, U.P. Agarwal, L.M. Matuana, R.C. Sabo, N.M. Stark, Effect of Lignin on the Performance Improvement of Poly (lactic acid) filled with Lignin-containing Cellulose Nanocrystals, Polymer, Submitted Sept. 20, 2017.
- Type:
Journal Articles
Status:
Accepted
Year Published:
2017
Citation:
S.S. Karkhanis, N.M. Stark, R.C. Sabo, and L.M. Matuana, Performance of Poly(Lactic Acid)/Cellulose Nanocrystal Composite Blown Films Processed by two Different Compounding Approaches, Polymer Engineering & Science, Submitted Aug. 14, 2017.
- Type:
Journal Articles
Status:
Published
Year Published:
2017
Citation:
Sonal S. Karkhanis, Nicole M. Stark, Ronald C. Sabo and Laurent M. Matuana, Blown Film Extrusion of Poly(Lactic Acid) Without Melt Strength Enhancers, Journal of Applied Polymer Science, 134 (34): article 45212 (10 pages) doi: 10.1002/app.45212 (2017).
- Type:
Journal Articles
Status:
Submitted
Year Published:
2017
Citation:
L. Wei, U.P. Agarwal, K.C. Hirth, L.M. Matuana, R.C. Sabo, N.M. Stark, Chemical Modification of Nanocellulose with Canola Oil Fatty Acid Methyl Ester, Carbohydrate Polymers, 169: 108-116 doi.org/10.1016/j.carbpol.2017.04.008 (2017)
- Type:
Journal Articles
Status:
Accepted
Year Published:
2017
Citation:
L. Wei, S. Luo, A.G. McDonald, U.P. Agarwal, K.C. Hirth, L.M. Matuana, R.C. Sabo, N.M. Stark, Preparation and Characterization of the Nanocomposites from Chemically Modified Nanocellulose and Poly(lactic acid), Journal of Renewable Materials, Accepted May 2017
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2017
Citation:
S.S. Karkhanis, L.M. Matuana, N.M. Stark, R.C. Sabo, Effect of Compounding Approaches on Fiber Dispersion and Performance of Poly (Lactic Acid)/Cellulose Nanocrystal Composite Films in Proceedings, ANTEC, Annual Technical Conference, Society of Plastics Engineers, May 8-10, 2017, Anaheim, CA.
- Type:
Theses/Dissertations
Status:
Published
Year Published:
2016
Citation:
Sonal Sanjay Karkhanis, Strategies To Manufacture Poly(Lactic Acid) Blown Films Without Melt Strength Enhancers, Packaging - Master of Science Thesis, Michigan State University (2016), 105 pages.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2017
Citation:
L.M. Matuana*, S.S. Karkhanis, N.M. Stark, and R.C. Sabo, Barrier Properties of Sustainable Bio-Plastic Films Filled with Cellulose Nanocrystals in Proceedings, the 2017 Advancements in Fiber-Polymer Composites Symposium, Madison, WI, May 16-18, 2017
|
Progress 10/01/15 to 09/30/16
Outputs
Target Audience:The information gathered during this research are being incorporated into several undergraduate and graduate courses on materials taught at MSU. They are used asexamples in classes taught by Dr. Matuana at MSU (e.g., PKG 323 Packaging with Plastics, PKG 827 Polymeric Packaging Materials, PKG 828 Processing and Applications of Packaging Plastics,etc.) and other universities. The findings of this project are disseminated to the broader scientific community through publications in scientific journals, the World Wide Web, and presentations at the national and/or international annual conferences on biomaterials. Dr. Matuana will create a website page that will highlight the results of this project (or publications) so they will be available to the farmers, companies, public, and scientific community interested in sustainable biomaterials. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?This research project provides (provided) training and/or professional development to the following individuals at Michigan State University: Dr. Cheng Xing, a postdoctoral fellow; Ms. Ms. Sonal Karkhanis, graduate students (MS level) as well as the following undergraduate students: Mr. Cameron Friesen, Ms. Anna Marra, Ms. Lauren Chard, Allison Friebe, Victoria Jansz, and Hannah Brubaker. How have the results been disseminated to communities of interest?Peer review publications and conference meetings. What do you plan to do during the next reporting period to accomplish the goals?The dispersion of CNCs is very important in order to improve the barrier properties, transparency, and other properties of the films. Our goal is to achieve nanosize dispersion of CNC in order to gain additional improvements in the mentioned properties. Therefore, our on-going work focusses on evaluating the effect of CNC contents and surface modification on its dispersion using X-ray diffraction method (XRD). The XRD results will complement the UV-vis, SEM, and light microscopy data. From these tests, strategies to enhance CNC dispersion into PLA will be developed. Also, mechanical, thermal, rheological properties of CNC/PLA composites will be determined.
Impacts
What was accomplished under these goals?
Processing strategies was developed to manufacture blown PLA films without any melt strength enhancers. The study examined the effects of various processing conditions and material parameters on the melt rheology, thermal property, and blow up ratios of the films. Experimental results indicate that the extrusion-blown PLA films can be successfully manufactured without melt strength enhancers. Irrespective of the degree of crystallinity, stable PLA films with a blow-up ratio of 5 were achieved in this study by controlling the melt rheology through processing conditions such as the temperature, film take up ratio, internal air pressure, and external cooling air pressure. We examined the effect of cellulose nanocrystal (CNC) addition on the water vapor and oxygen transmission rates of extrusion-blown poly(lactic) acid (PLA)/CNC nanocomposite films recorded at various temperatures and relative humidities (RH). Experimental results indicate that the addition of CNCs into PLA matrix through a melt processing approach improves the barrier properties of PLA, irrespective of RH or temperature. The addition of only 1% CNC into PLA matrix improved the water vapor and oxygen barrier performance of nanocomposite films by 33% and 62% respectively due to the tortuosity effect caused by cellulose nanocrystals-induced crystallinity in the matrix. Both RH and temperature had less influence on water vapor barrier properties when CNCs were added into the films. This implies that novel bio-based composites with improved barrier properties suitable for packaging applications (e.g., food packaging to extend food shelf life) could be developed by combining CNCs with PLA. The dispersion and distribution of CNCs (0.5 to 2 wt.%) in PLA matrix were evaluated using a light microscope. The results indicate that CNCs (unmodified and transesterified) were distributed homogenously, irrespective of the blending technique (dry blending and melt blending) and surface modification of CNC. However, some agglomerates were still visible. The effect of unmodified CNC concentration on the transparency of the film prepared using the dry blending technique was measured by ultraviolet-visible spectrophotometry (UV-Vis). Transparency can be used as an indicator of the dispersion of the nanoparticles in a matrix, if the size of individual nanoparticles is smaller than the wavelength of visible light. The UV-spectroscopy results showed that the light transmittance of the neat PLA slightly decreased from ~91.5% to ~86.1% by adding up to 0.5% CNC, and leveled off at ~77.5% as the CNC content increased further. Although there is still need for improvement to completely eliminate the agglomeration, the transparency of about 80% was achieved in this study, clearly indicating that good dispersion of CNC occurred in PLA matrix.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2016
Citation:
Cheng Xing and Laurent M. Matuana, "Epoxidized Soybean Oil-Plasticized Poly(Lactic Acid) Films Performance as Impacted by Storage," Journal of Applied Polymer Science, 133, 43201 (8 pages).
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2016
Citation:
L.M. Matuana, S.S. Karkhanis, and N.M. Stark, Strategies to Manufacture Extrusion-Blown PLA films without Melt Strength Enhancers The 14th International Symposium on Bioplastics, Biocomposites & Biorefining: Sustainable Bio-economy to Marketplace. May 31 to June 03, 2016.
Guelph, Ontario, Canada.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2016
Citation:
L.M. Matuana, S.S. Karkhanis, N.M. Stark, and R.C. Sabo, Cellulose Nanocrystals as Barrier Performance Enhancer of Extrusion-Blown PLA Films for Food Applications . The 2016 TechConnect World & National Innovation Conference-Nanotech2016, Washington, DC May 22-25, 2016.
|
Progress 10/01/14 to 09/30/15
Outputs
Target Audience:The information gathered during this research are being incorporated into several undergraduate and graduate courses on materials taught at MSU. They are used as tutorial examples in classes taught by Dr. Matuana at MSU (e.g., PKG 323 Packaging with Plastics, PKG 827 Polymeric Packaging Materials, PKG 828 Processing and Applications of Packaging Plastics,etc.) and other universities. The findings of this project are disseminated to the broader scientific community through publications in scientific journals, the World Wide Web, and presentations at the national and/or international annual conferences on biomaterials. Dr. Matuana will continue to update a website page that will highlight the results of this project (or publications) so they will be available to the farmers, companies, public, and scientific community interested in sustainable biomaterials. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?This research project provides training and/or professional development to the following individuals at Michigan State University: Dr. Cheng Xing, a postdoctoral fellow; Ms. Mamata Tathe and Ms. Sonal Karkhanis, graduate students (MS level) as well as the following undergraduate students: Mr. Cameron Friesen, Ms. Anna Marra, Ms. Lauren Chard, and Ms. Marie Yaccarino. How have the results been disseminated to communities of interest?Peer reviewed publication and conference meetings. What do you plan to do during the next reporting period to accomplish the goals?As mentioned above, currently we are investigating the effect of CNCs addition on the performance of filled PLA blown films in terms of water and gas barrier, optical, and other physico-mechanical properties. Blowing of PLA films is challenging because of its low melt strength compared to other polymers. The use of melt strength enhancers (MSEs) is commonly suggested to facilitate the production of PLA blown films. However, most of commercially available MSEs are not approved for food contact. We are attempting to develop strategies to blow PLA films without using MSEs.
Impacts
What was accomplished under these goals?
PLAwas successfully plasticized with epoxidized soybean oil (ESO). The impact strength and the ductility of plasticized sheets increased significantly with the ESO content; and the brittle-to-ductile transition occurred in the range of 5-10 wt% ESO content. This toughening capacity of ESO as a plasticizer was attributed to its partial miscibility with the matrix. In contrast, both the tensile strength and the modulus of the sheets decreased with increasing ESO content due to the plasticization effect, which induced a decrease in the glass transition temperature. Additionally, the plasticization of PLA film with ESO did not affect its heat sealability during flexible pouch manufacturing as indicated by the burst pressure and the seal strength, which remained unaffected by the addition of plasticizer, irrespective of the sealing temperature studied. The results of this work have been published inMacromolecular Materials and Engineering, 299 (5): 622-630 (2014). doi: 10.1002/mame.201300226?. Although we have successfully overcome the brittleness drawback and have developed a means to plasticize PLA with epoxidized soybean oils (ESO), a biobased oil, in order to enhance the materials flexibility, the permanency of the plasticizer in the film remained one of the concerns Dr. Matuana's group has. Two problems could arise if the plasticizer leaches out from the film: (1) The film will lose its flexibility and (2) the oil (ESO) could migrate and potentially contaminate the packaged product. Thus, this project is ongoing and our current objective is to address this concern, i.e., to determine the permanency of ESO in the plasticized film. The effect of storage on the performance of ESO plasticized PLA films manufactured through a cast extrusion process was investigated during this reporting period. Films plasticized with 10 wt% ESO were stored in a dessicator at room temperature and the melt viscosity, thermal, and tensile properties were measured over a minimum of 90 days of storage. Additionally, infrared spectroscopy was used to monitor plasticizer migration to the surface of plasticized film. Plasticizer migration occurred within the first 30 days of storage, which significantly affected the properties of plasticized films. While the melt viscosity, glass transition temperature, degree of crystallinity, tensile strength and modulus increased, the elongation at break and energy to break in contrast decreased with the storage time up to around 30 days and all properties remained constant thereafter suggesting that the films lost some flexibility during storage. However, the ability of stored plasticized film to cold crystallize was unaffected since both the cold crystallisation temperature and melting temperature were not affected during storage. Although the storage time led to property changes, plasticized PLA films still remained more flexible than the unplasticized counterpart even after 90 days storage. This result indicates that sufficient plasticization performance still remained in ESO-plasticized PLA films for flexible packaging application even after a long storage period at ambient conditions. In another project, we are investigating the use of cellulose nanocrystals (CNCs) to improve the water barrier properties of PLA. Water barrier is detrimental for packaged dried food because moisture uptake is associated with food spoilage due to molds and other microorganisms. This project is on-going and our preliminary results indicate that the processing conditions such as temperature, speed and residence time are crucial in dispersing CNCs into PLA matrix. The dispersion of CNS is very important in order to improve not only the water barrier properties of PLA film but also other properties of the films.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2014
Citation:
S. Vijayarajan, S.E.M. Selke, and L.M. Matuana, Continuous Blending Approach in the Manufacture of Epoxidized Soybean-Plasticized Poly(Lactic Acid) Sheets and Films, Macromolecular Materials and Engineering, 299 (5): 622-630 (2014).
- Type:
Journal Articles
Status:
Submitted
Year Published:
2015
Citation:
C. Xing and L.M. Matuana, "Epoxidized Soybean Oil-Plasticized Poly(Lactic Acid) Films Performance as Impacted by Storage," Journal of Applied Polymer Science. Submitted in August 2015.
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Progress 11/18/13 to 09/30/14
Outputs
Target Audience: The information gathered during this research are being incorporated into several undergraduate and graduate courses on materials taught at MSU. They are used as tutorial examples in classes taught by Dr. Matuana at MSU (e.g., PKG 323 Packaging with Plastics, PKG 827 Polymeric Packaging Materials, PKG 828 Processing and Applications of Packaging Plastics, etc.) and other universities. The findings of this project will be disseminated to the broader scientific community through publications in scientific journals, the World Wide Web, and presentations at the national and/or international annual conferences on biomaterials. Dr. Matuana will continue to update a website page that will highlight the results of this project (or publications) so they will be available to the farmers, companies, public, and scientific community interested in sustainable biomaterials. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? This research project provides training and/or professional development to the following individuals at Michigan State University: Dr. Cheng Xing , a postdoctoral fellow; Ms. Mamata Tathe, a graduate student (MS level) as well as the following undergraduate students: Ms. Kristi Hughes, Ms. Laurent Ryder, Mr. Jason Schon, Mr. Cameron Friesen, Ms. Ann Marie Yaccarino. How have the results been disseminated to communities of interest? Peer reviewed publication and conference meetings. What do you plan to do during the next reporting period to accomplish the goals? As mentioned above,currently the permenancy of ESO within PLA is under investigation as well as the effect of CNCs addition on the performance of filled PLA film in terms of water and gas barrier, optical, and other physico-mechanical properties.
Impacts
What was accomplished under these goals?
The widespread applicability of PLA in flexible sheets and films is limited because of its brittleness, lower impact resistance at room temperature and narrow processing window. These factors severely hinder its use, particularly in packaging applications where production lines for flexible films cannot tolerate film cracking or tearing when folded or subjected to force during manufacturing. Therefore, it is of paramount importance to find a tougher and more ductile variant of the polymer in order to overcome these difficulties and broaden the range of its commercial applications. A single-step processing system in which an extruder and a peristaltic injector pump attached in tandem was developed for continuous and accurate incorporation of epoxidized soybean oil (ESO) into a poly (lactic acid) (PLA) matrix in order to enhance the flexibility and toughness of PLA sheet and film. We have evaluated the effect of different ESO concentrations on the impact strength, ductility, and other tensile properties of PLA/ESO blends in order to determine the brittle-to-ductile transition. Additionally, the glass transition temperature and phase morphology of the blends were studied. The plasticization effect on the heat sealability of PLA film during pouch manufacture was also evaluated by measuring both the burst pressure and seal strength of the films. The results clearly demonstrate that PLA was successfully plasticized with epoxidized soybean oil (ESO). The impact strength and the ductility of plasticized sheets produced using this system significantly increased with the ESO content; and the brittle-to-ductile transition occurred in the range of 5-10 wt% ESO content. This toughening capacity of ESO as a plasticizer was attributed to its partial miscibility with the matrix. In contrast, both the tensile strength and the modulus of the sheets decreased with increasing ESO content due to the plasticization effect, which induced a decrease in the glass transition temperature. Additionally, the plasticization of PLA film with ESO did not affect its heat sealability during flexible pouch manufacturing as indicated by the burst pressure and the seal strength, which remained unaffected by the addition of plasticizer, irrespective of the sealing temperature studied. This work is on-going and currently the permenancy of ESO within PLA is under investigation. Although we have successfully overcome the brittleness drawback and have developed a means to plasticize PLA with epoxidized soybean oils (ESO), a biobased oil, in order to enhance the materials flexibility, the permanency of the plasticizer in the film remains one of the concerns Dr. Matuana’s group has. Two problems could arise if the plasticizer leaches out from the film: (1) The film will lose its flexibility and (2) the oil (ESO) could migrate and potentially contaminate the packaged product. Thus, this project is on-going and our current objective is to address this concern, i.e., to determine the permanency of ESO in the plasticized film. In another project, we are investigating the use of cellulose nanocrystals (CNCs) to improve the water barrier properties of PLA. Water barrier is detrimental for packaged dried food because moisture uptake is associated with food spoilage due to molds and other microorganisms.This project is on-going and our preliminary results indicate that the processing conditions such as temperature, speed and residence time are crucial in dispersing CNCs into PLA matrix. The dispersion of CNS is very important in order to improve not only the water barrier properties of PLA film but also other properties of the films.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2014
Citation:
S. Vijayarajan, S.E.M. Selke, and L.M. Matuana, Continuous Blending Approach in the Manufacture of Epoxidized Soybean-Plasticized Poly(Lactic Acid) Sheets and Films, submitted to Macromolecular Materials and Engineering, 299 (5): 622-630 (2014)
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