Well-dispersed and unaligned multi-walled carbon nanotubes (MCNTs) infused liquid epoxy adhesive have been reported for significantly improving the adhesive-joint of carbon fiber reinforced polymer (CFRP) composite laminates. However, it has not been determined in the literature if the alignment of MCNTs would provide an additional improvement than the randomly aligned case. In this study, various epoxy film adhesives embedded with 1wt% through-thickness aligned MCNTs, unaligned MCNTs, aligned carbon nanofibers (CNFs), and unaligned CNFs were used for bonding CFRP laminates. These variants have been used to bond two CFRP laminates for the ASTM D5868-01 single lap test as well as a steel variant for the same bonding process. The average shear strengths of the samples bonded by the various film adhesives were compared with the samples bonded by the pure epoxy-films. Microscopic analysis has been used to examine the fracture surface after testing. It was also used to visualize how the film adhesives fail while experiencing shear. This study has investigated the effectiveness of infusing through-thickness directionally aligned vs. unaligned nanoparticles in an epoxy film adhesive for bonding CFRP laminates and steel plate. It also indicates the potential future research direction of using nanoparticles in advanced adhesive technologies.
more »
« less
Biodegradable waterborne polyurethane‐urea dispersion adhesives with high biocontent
Non‐biodegradable petroleum‐based plastic wastes have become a leading environmental concern, and new efforts are underway to prepare biobased and biodegradable replacements. We have explored the preparation of adhesives suitable for use in consumer products, and here we report the development of waterborne, biodegradable adhesives from biobased monomers resulting in adhesives exceeding 70% biocontent. Using water as the polymer medium, viscosity challenges and the use of volatile organic solvents are avoided. Material properties of the polyurethane dispersions, resulting films, and laminates produced showed Mwranging between 56,000 and 124,000. Lastly, the biodegradability of films and laminates was evaluated. The resulting metrics indicate that the adhesives produced meet the desired mechanical and biodegradability targets, indicating that high renewability content solvent‐free polyurethane dispersions are a viable solution for lamination adhesives.
more » « less- Award ID(s):
- 2011924
- PAR ID:
- 10506214
- Publisher / Repository:
- Wiley
- Date Published:
- Journal Name:
- Journal of Applied Polymer Science
- Volume:
- 140
- Issue:
- 34
- ISSN:
- 0021-8995
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
more » « less
ABSTRACT Poly(lactic acid) (PLA) has a significant potential as a biodegradable polymer, but its high cost and slow biodegradability restrict its use in disposable products. This study establishes a novel route to accomplish both objectives by the addition of low‐cost soy fillers into PLA, which reduced material cost and increased the degradation rate of resulting soy‐PLA fibers. Due to partial thermal degradation of soy fillers at PLA melt temperature, they could be melt‐compounded into PLA up to 5 wt%. Fine continuous fibers (D ∼ 25‐50 μm) were successfully produced via melt spinning, and further melt‐consolidated into prototypical nonwovens. The tensile strength of soy‐PLA fibers containing soy reside and soy flour were 56 ± 9 and 44 ± 5 MPa, respectively. Although slightly lower than that of neat PLA fibers (74 ± 2 MPa), the fibers possessed adequate tenacity for use as nonwoven fabrics. Fiber modulus remained unaffected at about 2.5 GPa. The soy‐PLA fibers displayed a relatively rough exterior surface and provided a natural‐fiber feel. The overall degradation of soy‐PLA fibers was accelerated about 2‐fold in a basic medium due to the preferential dissolution of soy that led to increased surface area within the PLA matrix indicating their potential for use in biodegradable nonwovens.
-
more » « less
Abstract In 2014, almost 16 million tons of surfactants were used globally for cleaning and industrial applications. As a result, massive quantities disperse into environmental compartments every day. There is great market interest in developing highly biodegradable, less‐toxic, and renewable alternatives to currently used petroleum‐based surfactants. Glycolipid surfactants, composed of a sugar headgroup and lipid tail, are effective surfactants and emulsifiers with a high tolerance to electrolytes and are easily tailored to address specific needs. The green synthesis and surfactant characteristics of a suite of cellobiosides and melibiosides were recently described. The biodegradability and toxicity of 1°‐alkyl‐O‐cellobiosides, 2°‐alkyl‐O‐cellobiosides, and 1°‐alkyl‐O‐melibiosides with straight‐chain alkyl tails of 8, 10, and 12 are reported in this study. Biodegradability was assessed by quantifying mineralization (CO2evolution). All of the glycosides were inherently biodegradable and most were readily biodegradable according to OECD and US environmental protection agency (EPA) definitions. The Microtox acute toxicity assay showed both chain length and headgroup had significant effects on toxicity, but most of the molecules were practically nontoxic according to EPA definitions with EC50values >100 mg L−1. Cytotoxicity to human lung (H1299) and keratinocyte cell lines (HaCaT) was measured by xCELLigence and MTS assays. Cytotoxicity values were comparable to similar glycosides previously reported. IC50values were determined but in general, exceeded surfactant concentrations that are found in the environment. These data demonstrate the promising nature of these molecules as green alternatives to petrochemical surfactants.
-
Matthew, A ; Radhika, P ; Vijaya, R (Ed.)more » « less
Abstract In the present work, we report the effect of low‐temperature plasma treatment on thermal, mechanical, and biodegradable properties of polymer composite blown films prepared from carp fish scale powder (CFSP) and linear low‐density polyethylene (LLDPE). The CFSP was melt compounded with LLDPE using a filament extruder to prepare 1, 2, and 3 wt.% of CFSP in LLDPE polymer composite filaments. These filaments were further pelletized and extruded into blown films. The blown films extruded with 1, 2, and 3 wt.% of CFSP in LLDPE were tested for thermal and mechanical properties. It was observed that the tensile strength decreased with the increased loading content of CFSP, and 1% CFSP/LLDPE exhibited the highest tensile strength. To study the effect of low‐temperature plasma treatment, 1% CFSP/LLDP polymer composite with high tensile strength was plasma treated with O2and SF6gas before blow film extrusion. The 1% CFSP/LLDPE/SF6‐extruded blown films showed increased thermal decomposition, crystallinity, tensile strength, and modulus. This may be due to the effect of crosslinking by the plasma treatment. The maximum thermal decomposition rate, crystallinity %, tensile strength, and modulus obtained for 1% CFSP/LLDPE/SF6film were 500.02°C, 35.79, 6.32 MPa, and 0.023 GPa, respectively. Furthermore, the biodegradability study on CFSP/LLDPE films buried in natural soil for 90 days was analyzed using x‐ray fluorescence. The study showed an increase in phosphorus and calcium mass percent in the soil. This is due to the decomposition of the hydroxyapatite present in the CFSP/LLDPE biocomposite.
-
Previous studies have provided evidence that reinforcement of epoxy adhesives with nanostructures such as carbon nanofibers (CNFs) produces higher strength bonded joints between carbon fiber reinforced polymer (CFRP) laminates and shifts bond-line failure modes from the adhesive into the laminate. Despite this, there has been no research dedicated to applying reinforced adhesives to the bonding of nano-reinforced CFRP such as CNF z-threaded carbon fiber reinforced polymer (ZT-CFRP) laminates, which have been proven to exhibit increased interlaminar shear strength, mode-I delamination toughness, and compressive strength over traditional CFRP. This study examined the effectiveness of using CNF reinforced epoxy adhesives for unidirectional ZT-CFRP laminate bonding through single-lap shear tests using the ASTM D5868-01 standard. Unidirectional CFRP laminate samples bonded with both epoxy adhesive and CNF reinforced epoxy adhesive were also tested for comparison. It was found that the average shear strength observed for ZT-CFRP samples bonded with CNF reinforced epoxy adhesive was approximately 44% and 26 % higher than that of CFRP samples bonded with epoxy adhesive and CNF reinforced epoxy adhesive, respectively. Microscopic image analysis was performed to examine the mode of bond failure. The roles of nanomaterials in the fracture mechanism of the adhesives and the composite laminates are also discussed.more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1002/app.54307
