Adhesives transportation industry

A variety of applications exist for liquid, 100% solid adhesives, (An adhesive is considered 100% solid if there is no solvent in the adhesive.) Some of the largest uses include structural wood adhesives and adhesives used for the transportation industry, such as windshield adhesives and those used for bonding composite sidewalls of a recreational vehicle (RV). Structural wood adhesives are often made of a polymeric MDI with functionality of approximately 2.7 or higher. Rigid assemblies often utilize polymeric MDI, whereas flexible adhesive assemblies will more often utilize pure MDI, a solid waxy material that melts at around 37°C, or a modified MDI , i.e., MDI that has been modified to make it a liquid at room temperature. Prepolymers are made with ratios of anywhere from NCO/OH = 1.6 to 3.0 or higher. 

The aerospace field is a broad one and has a complex history. A comprehensive review of structural adhesive applications on currently flying aerospace vehicles alone could fill its own book. Hence this chapter will concentrate on the aerospace commercial transport industry and its use of adhesives in structural applications, both metallic and composite. Both primary structure, that is structure which carries primary flight loads and failure of which could result in loss of vehicle, and secondary structure will be considered. Structural adhesives use and practice in the military aircraft and launch vehicle/spacecraft fields as well as non-structural adhesives used on commercial aircraft will be touched on briefly as well. 

Structural adhesives based on polyurethanes are used widely in the transport industry, especially for bonding plastics reinforced with glass or other fibres. They are used also as sealants in glazing for motor vehicles—most notably following the introduction in recent years of front and rear windows bonded as elements in the construction. 

Epoxy-polysulfide systems are used in the construction, electrical, and transportation industries because of their unique combination of cured flexibility, adhesion to many substrates, and chemical resistance. They are typically used as adhesives for... 

Urethane structural adhesives have been very popular for bonding of plastics to plastics and plastics to metal by the transportation industry. As an example, more than 90% of the bonds in Fords experimental graphite car were urethane adhesives rather than rivets or welds. Urethane structural adhesives have been used by the transportation industry since 1969. It is estimated that 5 million pounds of urethane structural adhesives were used in the transportation industry in the United States in 1979. Some of the advantages of urethane adhesives as used by the transportation industry are shown in Table IX. 

They also can be used with little precleaning of surfaces to be bonded. They produce good durable bonds and overall they are cost effective. Some authorities are predicting growth of 300 to 400% in the next 5 years in the use of structural adhesives by the transportation industry. With the rush of the automobile companies to convert to plastics because of energy requirements, it is not unlikely that this will occur. 

The first use of adhesives to bond components and assemblies in the manufacture of buses dates back to the early 1980s. The modern transportation industry now depends on elastic adhesives for a whole range of fastening applications -... 

In addition to the stresses caused by expansion and contraction, fracture toughness must be considered. Impact is a serious concern, especially in the transportation industry. The bond must be able to survive substantial stress from impact without fracture, which would result in adhesive failure. Fracture tests are commonly performed at ambient conditions as well as in extreme cold (e.g., from 20°C to as cold as -40°C). At these extreme temperatures, many adhesives... 

Polyolefins belong to the most widely used class of polymers in many applications, such as in packaging, building, or transport industries. A combination of polyolefins with other materials can lead to an improvement of various properties. Many polyolefins belong among nonpolar polymers with low polarity and surface energy these polymers excel rather poor adhesion properties with various materials [1], and therefore, these polyolefins require the improvement of their surface and adhesive properties for many applications. In practice, the modification procedure selection for the improvement of the adhesion properties of diflerent polyolefins depends mostly on the required demands for the adhesive joints [2]. 

The transportation industry is probably the largest single user of urethane structural adhesives. This is in part due to the introduction of... 

The use of adhesives and sealants in the transportation industry is widespread. They are used at all stages in the production of components, final assembly, and after the vehicles are sold. 

The transportation industry represents a large market for a wide variety of adhesives and sealants. In 1989, 585 million wet pounds of these materials were used, 92% of which was in autos, trucks, buses and recreational vehicles. The aircraft and aerospace market consmned 6% and the boat industry 2%. 

Nanostructured polymer blends have drawn considerable interest because of their enhanced properties, including flame resistance, mechanical properties, gas-barrier properties [37-39], thermal stability, and biodegradability when compared with pristine polymers. Nanostructured polymer blends have also been used in various consumer products and in construction and transportation industries, with specific impact on technologies, such as barrier layer materials, drinks packaging applications, bottle applications, protective coatings, and adhesive molding compounds. 

Epoxies generally have excellent adhesion to metals, ceramics and glass, although on most amorphous thermoplastics epoxies will usually he outperformed by MMA, UV adhesives or cyanoacrylates. Epoxies will bond well to thermoset plastics and are widely used for bonding sheet moulding compound door and body panels in the transportation industries. Epoxies do not adhere well to elastomers, fluoropolymers or polyolefin plastics. 

Another important application area for PSAs in the electronic industry focuses on the manufacturing, transport and assembly of electronic components into larger devices, such as computer disk drives. Due to the sensitivity of these components, contamination with adhesive residue, its outgassing products, or residue transferred from any liners used, needs to be avoided. Cleanliness of the whole tape construction becomes very critical, because residuals like metal ions, surfactants, halogens, silicones, and the like can cause product failures of the electronic component or product. Due to their inherent tackiness, acrylic PSAs are very attractive for this type of application. Other PSAs can be used as well, but particular attention has to be given to the choice of tackifier or other additives needed in the PSA formulation. The choice of release liner also becomes very critical because of the concern about silicone transfer to the adhesive, which may eventually contaminate the electronic part. 

Perhaps the biggest thrust for the development of high performance polymers over the next 10 years will be in the aerospace industry where materials will be required for a fleet of high speed civil transports (supersonic transports). At a speed of Mach 2.4, an aircraft surface temperature of about 150 to 180°C will be generated. The life requirement of materials at these temperatures will be about 60000 hours. Many different types of materials such as adhesives, composite matrices, fuel tank sealants, finishes and windows will be needed. These materials must exhibit a favorable combination of processability, performance and price. The potential market for these materials total several billions of US dollars. 

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