SAE J3178:2020 pdf free

SAE J3178:2020 pdf free.Adhesives, Sealants, and Heat Transfer Materials in Battery Systems:A Primer on Materials, Applications, and End-Use Performance Requirements
As noted above, thermoplastics are generally solids that flow reversibly at elevated temperatures, allowing them to be processed into various shapes. Thermoplastics can be further categorized according to their morphological state, where these polymers exhibit either amorphous or semi-crystalline microstructure. The principle difference between amorphous and semi-crystalline polymers is how they soften with temperature, which is highlighted in Figure 1. The softening point where the polymer changes phase from a glass to a rubber (commonly called the glass transition temperature, Tg) is indicative of amorphous thermoplastic materials. Upon further heating, the system will soften to the point where it can flow under pressure to fill various molds or create other geometries. These attributes are very different from semi-crystalline thermoplastics that exhibit a continuum of amorphous polymer that harbors discrete areas of highly organized crystalline polymer (hence the term ‘ semi-crystalline”). Semi-crystalline thermoplastics are categorized by having both a glass transition temperature, Tg, and a crystalline melting point, Tm. Due to these discrete crystalline phases, a semi-crystalline material can typically withstand aggressive environments and yield higher thermal performance.
Thermoplastic materials are routinely modified via melt blending with other polymers, rubbers, fllers, and/or fibrous reinforcement. The resultant products can be formulated to exhibit high toughness, increased mechanical strength, and tremendous improvement in stiffness. It is common to formulate thermoplastics using these modifiers to produce pelletized products that can be stored for extremely long periods with no deleterious effects. These pellets, when softened (amorphous thermoplastics) or melted (semi-crystalline thermoplastics) via heat application, will flow under pressure to achieve shaped articles that have a desirable balance of mechanical performance attributes. Some examples of thermoplastics used in battery systems are liquid grease HTMs, hot melt adhesives, and low molecular weight olefins.SAE J3178 pdf free download.