Source: LOUISIANA STATE UNIVERSITY submitted to
EXTRUDED WOOD/NATURAL FIBER POLYMER COMPOSITES AS ADVANCED ENGINEERING MATERIALS
Sponsoring Institution
State Agricultural Experiment Station
Project Status
TERMINATED
Funding Source
Reporting Frequency
Annual
Accession No.
0213924
Grant No.
(N/A)
Project No.
LAB03903
Proposal No.
(N/A)
Multistate No.
(N/A)
Program Code
(N/A)
Project Start Date
Jul 1, 2008
Project End Date
Jun 30, 2013
Grant Year
(N/A)
Project Director
Wu, Q.
Recipient Organization
LOUISIANA STATE UNIVERSITY
202 HIMES HALL
BATON ROUGE,LA 70803-0100
Performing Department
School of Renewable Natural Resources
Non Technical Summary
Wood/Natural Fiber Polymer Composites (WNFPCs) are emerging as a viable alternative to glass fiber reinforced composites in various applications. These composites offer some inherent technical advantages over conventional composites like low cost, light weight, competitive specific mechanical properties, reduced energy consumption, and a "green" concept. Among these products, wood fiber polymer composite development has escalated very rapidly in the last few years. With increased wood costs and competition of wood resources from traditional wood sectors, developing alternative fiber sources is urgently needed. Agricultural production in the country (e.g., sugar and rice) generates significant amounts of bio-mass, which consists of high quality lignocellulosic fibers. For example, sugarcane refining generates a large volume of bagasse, containing both crushed high strength rind and pith fibers. Other agricultural fiber sources include rice, kenaf, and sorghum stalks. Use of these byproducts for value-added processes is highly needed. The general goal of this proposal is to develop WNFPCs through advanced extrusion technology. Specific objectives include studying quality attributes of wood and natural fibers (i.e., particle type and size) on composite properties; studying compatibility of natural fibers with common plastics for developing effective coupling agents and mechanisms among the various phases; developing and optimizing the extrusion technology for producing WNFPCs; and developing processes for enhancing the performance of WNFPCs against fire, insect, and decay through chemical additives and nanoparticles. This work will benefit agriculture, plastics and building industries, and the general public in Louisiana through developing superior composites using raw materials produced in the state.
Animal Health Component
(N/A)
Research Effort Categories
Basic
(N/A)
Applied
(N/A)
Developmental
(N/A)
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
51106502020100%
Goals / Objectives
The general goal of this proposal is to develop Wood/Natural Fiber Polymer Composites (WNFPCs) through advanced extrusion technology. Specific objectives include: 1. To study quality attributes of wood and natural fibers (i.e., particle type and size) on composite properties; 2. To study compatibility of natural fibers with common plastics for developing effective coupling agents and mechanisms among the various phases; 3. To develop and optimize the extrusion technology for producing WNFPCs; and 4. To develop processes for enhancing the performance of WNFPCs against fire, insect, and decay through chemical additives and nanoparticles. It is expected that the project will lead to the development of advanced technology for manufacturing extruded composite materials, new coupling forms and mechanisms, and viable commercial composite building products.
Project Methods
Fiber materials including wood, bagasse, rice straw, kenaf, and sorghum stalks will be processed to three different mesh sizes (20, 50, and 100). Three kinds of thermoplastic polymers will be used, including high density polyethylene (HDPE), polypropylene (PP), and polyvinyl chloride (PVC) pellets. Coupling agents will include two groups including maleated polyethylene (MAPE) and maleated polypropylene (MAPP) copolymers. Zinc borate will be used as additive for composite durability. Experimental design will include fiber/polymer ratios, compounding conditions, coupling agents and concentration, coupling agent/zinc borate ratio. The manufacture of the composites will be accomplished through an extrusion process. Fiber, thermoplastic, coupling agent, initiator, and other additives are first fed in the hopper and mixed with the one-step process. The mixture is then advanced along the barrel between the flights of the screw and the hot walls of the barrel. As the mixture moves along the extruder it is turned into a liquid by melting. The liquid melt is pressured and then moves from the extruder into a die, the first part of the forming system. The melt passes through the die as a sheet form with a designed thickness by water/air cooling. The sample is rolled out and finally cut into a designed dimension and finished to commercial standards. The interfacial characterization and structure, mechanical and thermal properties, and durability of the composites made from the study will be evaluated through morphology and functional analysis, strength testing, thermal analysis, and biological testing. The research results will be published through extension publications, technical conferences and refereed journal outlets.

Progress 07/01/08 to 06/30/13

Outputs
Target Audience: Wood and plastics composite industry, recycled plastics industry. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? The information generated by this project resulted in three Ph.D. dissertations (BJ Kim. Ph.D. in Forest Products - 2012, Yanjun Xu, Ph.D. in Forest Products - 2009, and Fei Yao, Ph.D. in Forest Products 2008), training of four postdoctoral research scientists (Runzhou Huang - Visiting Scientist : August 2010 to July 2013, Fei Yao - Postdoctoral Researcher: July 2008 to July 2010, Chengjun Zhou, Postdoctoral Researcher: August 2009 to December 2013, and Dagang Liu - Postdoctoral Researcher: November 2008 to August 2009), and ten presentations at national and international conferences. How have the results been disseminated to communities of interest? The results from this project have been disseminated through refereed journal papers, conference presentations andproceedings. A plastic and natural fiber composite formulation, trade-named as TigerBullets, was successfully commercialized to the oil industry as lost circulation control material. The significance and impact of the research was discussed with peer researchers and members of the wood plastic composite industry. 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 decomposition processes for ten types of natural fibers common used in the polymer composite industry were studied based on dynamic thermogravimetric analysis. The data were used to develop various degradation models to determine the apparent activation energy and degradation process of the fibers. The strength-toughness balance of natural fiber reinforced composites was optimized by simultaneously incorporating both PE-g-MA and EPR-g-MA. The optimal balance of composite properties was achieved at lower percentage of sEPR-g-MA and medium fiber loading level. Composites with reinforcing microfibers from recycled HDPE/PET and recycled HDPE/Nylon were developed through reactive extrusion and stretching. The resultant MFCs were easily processed at the normal temperature used for processing HDPE. The dispersed R-PET phase was stretched into in-situ microfibers through the pelletizing during extrusion. The micro-fibril composites (MFCs) provide potential matrix materials for natural fiber polymer composites, and the technique provides a technology to process co-mingled plastic mixtures from recycling streams. Accelerated creep tests were conducted at higher temperatures, and smooth curves were obtained based on the time temperature superposition (TTS) principle. Several factors affected the creep resistance of NFPCs, including polymer matrix type, natural fiber loading, additives, temperature, and weathering treatment. Introducing engineering plastics to form microfibrils in a HDPE matrix improved creep performance. Adding natural fibers into a polymer matrix greatly enhanced its creep resistance. An ultrafine titanium dioxide (UVA), slightly reduced the creep deformation of HDPE composites at a low loading level. Coextruded recycled polyethylene and wood-flour composites with core–shell structure were manufactured using a pilot-scale coextrusion line. The core–shell structured profile can significantly improve flexural and impact strengths of composites especially when a relatively weak core is used. However, the coextruded profile with unreinforced shell may have a reduced modulus when a strong core is used. The shell layer also protected coextruded composites from long-term moisture uptaking, leading to improved dimensional stability compared with the corresponding un-coextruded controls. When the shell thickness is fixed, less wood loading in the shell layer did not cause obvious flexural modulus and dimension change but improve impact strength and water resistance of the coextruded composites. When wood loading in the shell layer is fixed, increased shell thickness improves impact strength but affects modulus negatively. Thickened shell layer helps reduce water uptaking but did not change dimensional stability of coextruded composites remarkably. Overall enhancement of composite strength was more pronounced for the weaker core system. Thus, the coextrusion technology can be used to achieve acceptable composite properties even with a relatively weak core system—offering an approach to use recycled, low quality plastic-fiber blends in the core layer. A plastic (e.g., PET) and natural fiber composite formulation, trade-named as TigerBullets, was patented and commercialized to oil industry. Over 8,000,000 pounds of the TigerBullets have been manufactured and sold to some major oil companies. One technique of manufacturing transparent plastic reinforced with cellulose nano crystals also has been developed. Nano-sized cellulose crystals were fabricated from microcrystalline cellulose (MCC) using combined sulfuric acid hydrolysis and high-pressure homogenization. The crystals were utilized to prepare polymethylmethacrylate (PMMA) nanocomposites by the solution casting method.

Publications

  • Type: Journal Articles Status: Published Year Published: 2013 Citation: Xiong, W., Q. Wu, and C.S. Cai. 2013. Mechanical and Thermal performance of coextruded wood plastic composites for structural applications. Advances in Structural Engineering, 16(5): 909-930.
  • Type: Journal Articles Status: Published Year Published: 2013 Citation: Liu, T., Y. Lei, Q. Wang, S. Lee, and Q. Wu. 2013. Effect of fiber type and coupling treatment on properties of high-density polyethylene/natural fiber composites. BioResources. 8(3):4619-4632.
  • Type: Journal Articles Status: Published Year Published: 2013 Citation: Li, P., B. J. Kim, Q., Wang, and Q. Wu. 2012. Experimental and numerical analysis of sound insulation property of filled wood plastic composites (WPCs) filled with Precipitated CaCO3. Holzforschung 67(3): 301306.
  • Type: Journal Articles Status: Published Year Published: 2013 Citation: Huang, R., B.J. Kim, S.Y. Lee, Y. Zhang, and Q. Wu. 2013. Co-extruded wood plastic composites with talc-filled shells: morphology, mechanical, and thermal expansion performance. BioResources 8(2):2283-2299.
  • Type: Journal Articles Status: Published Year Published: 2013 Citation: Wu, Q., F. Yao, C. Mei, and D. Zhou. 2013. Thermal degradation of rice straw fibers: global kinetic modeling with isothermal thermogravimetric analysis. Journal of Industrial and Engineering Chemistry. 19 (2):670-676.
  • Type: Journal Articles Status: Published Year Published: 2013 Citation: Li, Y., Du, L., Kai, C., Huang, R., and Wu, Q. 2013. Bamboo and high density polyethylene composite with heat-treated bamboo fiber: Thermal decomposition properties. BioResources 8(1):900-912.


Progress 01/01/12 to 12/31/12

Outputs
OUTPUTS: The project generated four refereed journal papers in the field of extruded wood plastic composites. An invited presentation on extruded wood-plastic composites with pressured treated wood fibers was delivered at the 20th Annual International Conference on Composites or Nano Engineering (Beijing, China). PARTICIPANTS: Qinglin Wu, B.J. Kim, Runzhou Huang, LSU AgCenter. TARGET AUDIENCES: Wood-Plastic Composite Industry PROJECT MODIFICATIONS: None

Impacts
The influences of hybrid bamboo and precipitated calcium carbonate (PCC) fillers in a recycled polypropylene/polyethylene (R-PP/PE) matrix were evaluated on the properties of bamboo plastic composites. Thermogravimetric and FTIR analyses of both thermo-mechanically refined bamboo fibers (RBF) and ground bamboo particles (GBP) showed relatively higher holocellulose content in RBF, and more effective silane grafting on the RBF surface. The raw PCC particles contained over 95% CC, and had an agglomerated form consisting of particles with a mean diameter of about 1.2 microns. Compounding the PCC particles with the plastic resin helped separate and disperse them in the matrix. Measured flexural strength and modulus of PCC-only-filled composites increased significantly from 15 to 30% PCC content levels, while the tensile and impact strength of composites decreased with the addition of PCC. For composites with hybrid bamboo and PCC fillers, tensile and flexural moduli were improved with the increase of PCC content. After silane treatment, RBF filled composites showed a noticeable increase in mechanical properties compared to those of GBP filled composites. For modulus values, PCC-bamboo-polymer composites were 3-4 times higher than those of PCC-polymer composites at high PCC levels. Coextruded wood plastic composite (WPC) with glass-fiber (GF) filled shells were manufactured and their thermal expansion coefficients were evaluated. A three-dimensional finite element model considering differential properties of both shell and core was developed to predict the linear coefficient of thermal expansion (LCTE) of the material. The use of GF-filled shells enhanced overall composite modulus and strength, and at the same time, lowered composite LCTE. The imbalance of shell, core LCTE, and moduli led to complex stress fields within the composite system. The model predicted a trend, which is in general agreement with the experimental data. This study represents the first time a finite element modeling technique has been used to optimize raw material composition for minimizing thermal expansion behavior of co-extruded WPC.

Publications

  • Shang, L. G. Han, F. Zhu J. Ding, T. Shupe, Q. Wang, and Q. Wu. 2012. High-Density Polyethylene-based Composites with Pressure-treated Wood Fibers. Bioresources: 7(4):5181-5189.
  • Huang, R., W. Xiong, X. Xu, and Q. Wu. 2012. Thermal Expansion Behavior of Co-extruded Wood Plastic Composites with glass fiber Reinforced Shells. Bioresources: 7(4):5514-5526.
  • Huang, R., Y. Zhang, X. Xu, D. Zhou, and Q. Wu. 2012. Effect of Hybrid Mineral and Bamboo Fillers on Thermal Expansion Behavior of Bamboo Fiber and Recyled polypopylene polyethylene Composites. BioResources 7(4), 4563-4574.


Progress 01/01/11 to 12/31/11

Outputs
OUTPUTS: The information generated by this project was disseminated in 2011 in a total of two refereed research publications and two presentations at national and international conferences. The significance and impact of the research were discussed with peer researchers and members of wood-based composite industry. As the result of this research, one technique of using hybrid bamboo and precipitated calcium carbonate (PCC) fillers in wood plastic composites has been described. PARTICIPANTS: Wu, Q. (PI), Y. Fei, and B.J. Kim, LSU AgCenter. TARGET AUDIENCES: Wood/plastics composite industry, recycled plastics industry PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
The influences of hybrid bamboo and precipitated calcium carbonate (PCC) fillers in a recycled polypropylene/polyethylene (R-PP/PE) matrix on the properties of bamboo plastic composites were studied. Thermogravimetric and FTIR analyses of both thermo-mechanically refined bamboo fiber (RBF) and ground bamboo particle (GBP) showed relatively higher holocellulose content in RBF and more effective silane grafting on the RBF surface. The raw PCC particles contained over 95% CC and had an agglomerated form consisting of particles with a mean diameter of about 1.2 microns. Compounding the PCC particles with the plastic resin helped separate and disperse them in the matrix. Measured flexural strength and modulus of PCC-only-filled composites increased significantly from 15 to 30% PCC content levels, while the tensile and impact strength of composites decreased with the addition of PCC. For composites with hybrid bamboo and PCC fillers, tensile and flexural moduli were improved with the increase of PCC content. After silane treatment, RBF filled composites showed noticeably increased mechanical properties compared to those of GBP filled composites. For modulus values, PCC-bamboo-polymer composites were 3-4 times higher than those of PCC-polymer composites at high PCC levels.

Publications

  • Kim, BJ, F. Yao, G. Han, and Q. Wu. 2011. Performance of bamboo plastic composite with hybrid bamboo and precipitaed calcium carbonate fillers. Polymer Composites DOI 10.1002/pc.21244.
  • Zhou, C., R. Chou, R. Wu, and Q. Wu. 2011. Electrospun polyethylene oxide/cellulose nanocrystal composite nanofibrous mats with homogeneous and heterogeneous microstructures. Biomacromolecules: 12:2617-2625.


Progress 01/01/10 to 12/31/10

Outputs
OUTPUTS: From the research conducted, one journal paper was published. PARTICIPANTS: Qinglin Wu, Professor, School of Renewable natural resources, LSU AgCenter H. Liu, Postdoc Researcher, School of Renewable natural Resources, LSU AgCenter F. Yao, Postdoc Researcher, School of Renewable Natural Resources, LSU AgCenter TARGET AUDIENCES: Natural fiber/polymer composite manufacturers, biopolymer, general public PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
Polymethymethacrylate (PMMA) composites were successfully prepared by solution casting with the reinforcement of cellulose nanocrystals manufactured from microcrystalline cellulose (MCC) using sulfuric acid-hydrolysis combined with high-pressure homogenization techniques. Cellulose nanocrystals with an average length of 124 nm and an average diameter of 8-10 nm were obtained by acid-hydrolysis alone. The crystals were further shortened to about 62 nm through five high-pressure homogenization treatment passes. The DMA data showed a marked increase in storage modulus from 1.5 GPa for pure PMMA to 5 GPa for the composite sheet containing 10 wt% cellulose nanocrystals at 35 C because of the high modulus of cellulose crystals. The PMMA/CNs nanocomposites were transparent when low content cellulose crystals were composited. This technology can help manufacture highly reinforced transparent polymeric materials for optical applications. The material showed significantly improved strength properties.

Publications

  • Liu, H., D. Liu, F. Yao, and Q. Wu. 2010. Fabrication and properties of transparent polymethylmethacrylate/ cellulose nanocrystal composites. Bioresource Technology, 101:5685-5692.


Progress 01/01/09 to 12/31/09

Outputs
OUTPUTS: Based on a novel two-step extrusion process developed from this project, we were able to form microfibrillar co-blends with recycled high-density polyethylene (HDPE) and engineering plastics including poly(ethylene terephthalate)-PET and Nylon-6 for wood fiber plastics composite manufacturing. In the composite systems, both in situ formed Nylon-6 or PET microfibrils and wood fibers acted as reinforcing elements. The new composite system exhibited higher strengths and moduli than the corresponding HDPE-based composite. The incorporation of wood fiber and microfibrils from engineering plastics reduced short-term creep response of HDPE matrix. From these results three journal papers were published. The results will be used to convert used plastics into valuable composites. PARTICIPANTS: Qinglin Wu, Professor, School of Renewable natural resources, LSU AgCenter Yong Lei, Postdoc Researcher, School of Renewable natural resources, LSU AgCenter Hongzhi Liu, Postdoc Researcher, School of Renewable natural resources, LSU AgCenter TARGET AUDIENCES: Target audiences of this project include wood plastic composite manufacturers, plastics recyclers, and the general public. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
A novel kind of wood fiber-filled composite based on the microfibrillar HDPE/Nylon-6 blend was developed with two-step extrusion followed by injection molding. It was confirmed that Nylon-6 microfibrils were formed in the drawing step. Compared to the corresponding HDPE/Wood Fiber (WF) composite, the resultant composite based on the as-drawn HDPE/Nylon-6 blend exhibited superior strengths, moduli, and short-term creep-resistance performance. The two step extrusion approach successfully avoided undesired thermal degradation of WF and retained the integrity of the majority of Nylon-6 microfibrils by having a high melting temperature (Tm > 200 _C). This was accomplished by effectively combining isotropization of HDPE microfibrils with dispersion of WF into a single step. Microfibrillar composites (MFCs) from recycled high density polyethylene (R-HDPE)/recycled poly (ethylene terephthalate) (R-PET) (75/25 w/w) were also made through reactive extrusion and post-extrusion strand stretching. The resultant MFCs could be processed at HDPE processing temperature. The compatibility between microfibers and R-HDPE matrix was improved through compatibilizers. Of the three compatibilizers evaluated, ethylene glycidyl methacrylate copolymer (E-GMA) performed the best. The addition of compatibilizers did not obviously change the size of R-PET fibers in MFCs. The toughness of MFC was significantly enhanced, and R-PET phase did not crystallize when 5% E-GMA was used. The process of manufacturing MFCs provides a way to recycle commingled plastics, and MFCs would be potential matrices for natural fiber polymer composites.

Publications

  • Liu, H., Q. Wu, and Q., Zhang. 2009. Preparation and properties of banana fiber-reinforced composites based on high density polyethylene/Nylon-6 blends. Bioresource Technology 100:6088-6097. (Impact Factor=4.45)
  • Lei, Y., Q. Wu, and Q., Zhang. 2009. Microfibrillar composites based on recycled high density polyethylene and poly(ethylene terephthalate): morphological and mechanical properties. Composite Part A 40:904-912. (Impact Factor=1.66)
  • Lei, Y., Q. Wu, C. M. Clemons, and W. Guo. 2009. Phase structure and properties of poly(ethylene terephthalate)/high density polyethylene based on recycled materials. J. Applied Poly. Sci. 113:1710-1719 (Impact Factor=1.33)


Progress 01/01/08 to 12/31/08

Outputs
OUTPUTS: From the support of this project, our lab published five journal papers in 2008 in the field of wood/natural fiber plastics composites. The significance of the results obtained from this research will be shared with scientific communities. The study has also led to a patented process that combines empty quart bottles of motor oil, some residual oil, wood/natural fibers, and chemical additives and turns them into extruded pellets that can be used to make the composite materials for decking and outdoor furniture. PARTICIPANTS: Qinglin Wu, PI; Yong Lei, Postdoctoral Researcher, Fei Yao, Graduate Student, Yanjun Xu, Graduate Student TARGET AUDIENCES: Wood/plastics composite industry, recycled plastics industry PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
Plastics contaminated with oil, such as used motor oil containers, have been difficult to recycle due to the extensive cleaning process required. In our process, the collected oil containers are drained, crushed, and used directly to make wood plastic composites through reactive extrusion with maleic anhydride (MA) and maleated polyethylene (PE-g-MA) as coupling agents. The residual oil played a role as a plasticizer in influencing the melting behavior and mechanical properties of oil container plastics (OCP) and their composites, enhancing flowability and lowering strength and modulus. MA was better than PE-g-MA in enhancing properties of the oil container plastics containing residual oil (OOCP)/wood flour composite. The tensile and flexural strengths of the OOCP/wood flour composite were increased by 49.2% and 35.7%, respectively, by the addition of 2% MA. Addition of both PE-g-MA and MA effectively improved water resistance of the OOCP/wood flour composites, especially the addition MA. No poisonous heavy metals were leached out from OOCP/wood composites, and the residual oil in the composites was stable under heat or in the water. The OOCP/wood composite was successfully used to make composite profiles through blending with extrusion-grade recycled polyethylene. U.S. consumers use 3 billion plastic bottles each year, totaling over 165,000 metric tons (over 360 million pounds) of plastics. Most are buried in landfills together with about 60,000 metric tons (20 million gallons) of motor oil residue. This process can lead to potential plastics recovery of over $36M per year, plus new marketable composite products and the reduction of environmental pollution due to discarded oil and plastics.

Publications

  • Xu, Y., Q. Wu, Y. Lei, F. Yao, and Q. Zhang. 2008. Natural Fiber Reinforced Poly(vinyl chloride) Composites: Effect of Fiber Type and Impact Modifier. Journal of Polymers and the Environment 16(4):250-257.
  • Han, G., Y. Lei, Q. Wu, Y. Kojima, and S. Suzuki. 2008. Bamboo-fiber filled high density polyethylene composites: effect of coupling treatment and nanoclay. J. of Polymers and the Environment 16:123-130.
  • Liu, H., Q. Wu, G. Han, F. Yao, Y. Kojima, S. Suzuki. 2008. Compatibilizing and toughening bamboo flour-filled HDPE composites: mechanical properties and morphologies. Composite Part A. 39:1891-1900.
  • Yao, F., Q. Wu, Y. Lei, and Y. Xu. 2008. Rice straw fiber reinforced high density polyethylene composite: Effect of fiber type and loading. J. Industrial Crops and Products: 28:63-72.
  • Yao, F., Q. Wu, Y. Lei, W. Guo, and Y. Xu. 2008. Thermal decomposition kinetics of natural fibers: activation energy with dynamic thermogravimetric analysis. Polymer Degradation and Stability 93(1):90-98.
  • Wu, Q., and Y. Lei. 2008. Composites made of high density polyethylene motor oil containers and cellulosic fiber. International Patent Application number: PCT/US08/86057.