Adhesives and Sealants - March 2018
This month we're looking at Adhesives and Sealants.There is a wide range of synthetic polymeric adhesives and they can be subdivided into many groups, including pressure sensitive, contact, structural, and hot melt. The properties of these adhesives vary greatly and this is why they have such wide-ranging applications, from those that need to be strong and reliable enough for a space shuttle fuel tank, to those that must stick and peel like the glue on a post-it note. Sealants are very similar to adhesives in that they must bond well to varying materials, but are mainly used to coat materials to protect them in some way, particularly in potential weak spots. The wide variety of types of adhesives and sealants and their many applications result in consistently high levels of research.
We can help you can keep up-to-date with the latest technologies and developments in this industry. Why not read some of the latest literature in this area? There is a selection of abstracts from the Polymer Library on this subject below.
These abstracts were highlighted in the March 2018 Newsletter and found in the Polymer Library.
Click on the 7-digit accession numbers to find out about ordering a copyright-cleared full text copy of the items shown.
1272367 - Reshaping adhesive and sealant formulation strategies
The development of an engineered material, which is a free-flowing, organic-encapsulated, inorganic composite powder, which can simultaneously replace multiple ingredients and/or reduce consumption of commonly used and oftentimes higher-priced ingredients, such as titanium dioxide, plasticisers, bitumen, tackifiers, process oils, powdered coal and soft and hard clays, is reported. The organic phase is a high-softening-point oxidised asphaltene and resin-rich composition containing about 21/2 times more resins and asphaltenes than common bitumen. The use of this material in the formulation of hot melt adhesives for use in applications, such as flashing tape, roofing membranes and protective pipe wrap, and in three high-volume industrial rubber compounding applications is demonstrated. These applications are EPDM for hose covers, nitrile rubber for floor mats and SBR/BR blend for conveyor covers.
Adhesives and Sealants Industry, 24, No.10, Oct. 2017, p.20-25
1275362 - Characterization and performance of soy-based adhesives cured with epoxy resin (OPEN ACCESS - FREE ACCESS TO FULL TEXT)
Soy-based adhesives have attracted much attention recently because they are environmentally safe, low cost, and readily available. To improve the gluability and water resistance of soy-based adhesives, we prepared an enzyme-treated soy-based adhesive modified with an epoxy resin. We investigated the wet shear strength of plywood bonded with the modified adhesive using the boiling-water test. Fourier transformed infrared spectroscopy (FTIR) and ^1H nuclear magnetic resonance analysis were used to characterise the reaction between epoxy groups and -NH2 groups in the modified soy-based adhesives. FTIR analysis confirmed the cross-linking structure in the cured adhesives. Viscosity and the solid content of soy-based adhesives gradually increased with the increasing amount of epoxy resin, but had little effect on its operability. Wet shear strength of plywood samples increased as the amount of epoxy resin was increased, whereas the inverse trend was observed regarding the water absorption of cured adhesives. Compared to an unmodified adhesive, the addition of 30% of epoxy resin increased the wet shear strength of plywood samples by 58.3% (0.95 MPa), meeting the requirement of the Chinese National Standard for exterior plywood. Differential scanning calorimetry and thermogravimetric analysis showed the improved thermostability of the cured adhesives after curing at 160 deg C. These results suggest that epoxy resin could effectively improve the performance of enzyme-treated soy-based adhesives, which might provide a new option for the preparation of soy-based adhesives with high gluability and water resistance. 45 Refs.
Polymers, 9, No.10, Oct. 2017, paper 514, pp.11, DOI: 10.3390/polym9100514
Chen N; Zheng P; Zeng Q; Lin Q; Rao J
1275468 - Biobased adhesives: Requirements and perspective
During the 20th century, biobased adhesives lost their predominant importance, which is closely related to the scientific progress in synthetic polymer chemistry. Recent progress in biotechnology enables the green production of bio-renewable platform chemicals and specific design of functional proteins and peptides, which is expected to significantly impact adhesive development and create numerous new possibilities and applications. This article aims to discuss the requirements and perspective of biobased adhesives in our modern world. Polyfarnesene polyols offer novel opportunities in PU chemistry, e.g. high performing liquid applied optical clear adhesives as an important technology enabler for handheld devices, optical displays and lighting applications. Current research aims to utilise "adhesive peptides" as advanced adhesion promoters for the development of high-performing universal glues for a large variety of substrates. 7 refs.
Bioplastics Magazine, 12, No.6, Nov.-Dec. 2017, p.30-32, ISSN: 1862-5258:
Beck H; Taden A
1277651 - Graphite oxide improves adhesion and water resistance of canola protein-graphite oxide hybrid adhesive (OPEN ACCESS - FREE ACCESS TO FULL TEXT)
Protein derived adhesives are extensively explored as a replacement for synthetic ones, but suffers from weak adhesion and water resistance. Graphite oxide (GO) has been extensively used in nanocomposites, but not in adhesives applications. The objectives of this study were to prepare functionally improved protein adhesive by exfoliating GO with different oxidation levels, and to determine the effect of GO on adhesion mechanism. GO were prepared by oxidising graphite for 0.5, 2, and 4 h (GO-A, GO-B and GO-C, respectively). Increasing oxidation time decreased C/O ratio; while the relative proportion of C-OH, and C = O groups initially increased up to 2 h of oxidation, but reduced upon further oxidation. Canola protein-GO hybrid adhesive (CPA-GO) was prepared by exfoliating GO at a level of 1% (w/w). GO significantly increased (p (less than) 0.05) adhesion; where GO-B addition showed the highest dry, and wet strength of 11.67 (+/-) 1.00, and 4.85 (+/-) 0.61 MPa, respectively. The improvements in adhesion was due to the improved exfoliation of GO, improved adhesive and cohesive interactions, increased hydrogen bonding, increased hydrophobic interactions and thermal stability of CPA-GO. GO, as we proposed for the first time is easier to process and cost-effective in preparing protein-based adhesives with significantly improved functionalities. 61 Refs.
Scientific Reports, 7, paper 11538, 2017, pp.12, eISSN: 2045-2322, DOI: 10.1038/s41598-017-11966-8
Bandara N; Esparza Y; Wu J
1277868 - Natural and bio-inspired underwater adhesives: current progress and new perspectives (OPEN ACCESS - FREE ACCESS TO FULL TEXT)
Many marine organisms harness diverse protein molecules as underwater adhesives to achieve strong and robust interfacial adhesion under dynamic and turbulent environments. Natural underwater adhesion phenomena thus provide inspiration for engineering adhesive materials that can perform in water or high-moisture settings for biomedical and industrial applications. Here we review examples of biological adhesives to show the molecular features of natural adhesives and discuss how such knowledge serves as a heuristic guideline for the rational design of biologically inspired underwater adhesives. In view of future bio-inspired research, we propose several potential opportunities, either in improving upon current L-3, 4dihydroxyphenylalanine-based and coacervates-enabled adhesives with new features or engineering conceptually new types of adhesives that recapitulate important characteristics of biological adhesives. We underline the importance of viewing natural adhesives as dynamic materials, which owe their outstanding performance to the cellular coordination of protein expression, delivery, deposition, assembly, and curing of corresponding components with spatiotemporal control. We envision that the emerging synthetic biology techniques will provide great opportunities for advancing both fundamental and application aspects of underwater adhesives. 86 Refs.
APL Materials, 5, No.11, 2017, paper 116102, pp.20, ISSN: 2166-532X, DOI: 10.1063/1.4985756
Cui M; Ren S; Wei S; Sun C; Zhong C
1278106 - Reversible multi-material adhesive bonds
As the automotive industry moves towards use of multi-material vehicle structures, the ability to structurally join dissimilar materials and keep them together during the vehicle's useful life, yet also separate them to repair, rejoin them and then separate them again at end-of-life for recycling has become increasingly important. A multi-year research programme involving the American Chemistry Council's Plastics Division and Michigan State University, has yielded surprisingly effective results in its quest to develop reversible adhesive joints that can be debonded and rebonded multiple times. This capability could facilitate composites use in mixed-material vehicle structures because it gives adhesively bonded joints the durability and the reversibility of mechanically fastened joints at reduced weight. The team has used ferromagnetic (iron oxide) nanoparticles at loadings of 4-20% in a variety of thermoplastic adhesives. The team know how to adjust the surface chemistry of not only the polymers but also the nanoparticles and, therefore, can make the technology work in just about any thermoplastic adhesive system. The team has demonstrated that an adhesive joint can be rapidly unbonded in the presence of an electromagnetic field, then rebonded again with another round of electromagnetic energy.
Composites World, 4, No.1, Jan. 2018, p.24-27, ISSN: 2376-5232
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