Navigating the complex world of Thermoplastic Elastomers (TPE) requires a thorough understanding of its primary groups and their unique characteristics. This guide delves into the fascinating realm of non-polyolefinic TPEs, offering insights into their significant categories and practical applications.
Our journey begins with polyurethane-based TPEs, a diverse group that merits its standalone discussion, as introduced in the segment on different TPUs. We then transition to polyamide-based TPEs, known as TPAs, which are pivotal in automotive and industrial part manufacturing. These TPAs are categorized into three principal types, each engineered to meet specific user requirements:
TPA-EE: Featuring a soft segment composed of both ether and ester linkages.
TPA-ES: Characterized by its polyester soft segment.
TPA-ET: Distinguished by its polyether soft segment.
The narrative then shifts to Thermoplastic Copolyesters (TPCs), renowned for their role in crafting specialized automotive components. TPCs are segmented into three subgroups, each defined by their soft segments:
TPC-EE: Combining ester and ether in its soft segment.
TPC-ES: Incorporating a polyester soft segment.
TPC-ET: Utilizing a polyether soft segment.
Further, we explore the diverse world of TPSs, or styrene-based TPEs. This versatile category is employed in various industries, from automotive manufacturing to household appliances, and even in adhesives and sealants. TPSs are categorized based on their chemical microstructure into:
TPS-SBS: A block copolymer of styrene and butadiene.
TPS-SEBS: Consisting of polystyrene-poly(ethylene-butylene)-polystyrene.
TPS-SEPS: Made up of polystyrene-poly(ethylene-propylene)-polystyrene.
TPS-SIS: A block copolymer of styrene and isoprene.
In conclusion, it’s imperative to understand that the right selection of a TPE grade is pivotal and should be driven by the specific demands of the intended application. This strategic approach ensures that each application is matched with a TPE that offers optimal performance and functionality, tailored to meet the exacting standards of various industrial contexts.
Prior to the advent of TPEs, soft PVC compounds or rubbers were utilized in applications requiring flexibility, elasticity, and softness. However, with the development of various TPEs, this new family quickly replaced PVC or elastomer-based competitors in many applications. This section provides a qualitative comparison between the two available options for producing soft parts such as caps, plugs, and gaskets.
PVC, an accessible and inexpensive plastic, requires various additives such as stabilizers, plasticizers, lubricants, impact modifiers, fillers, etc., to form a suitable compound for diverse part production. PVC finds applications in a broad spectrum, ranging from window gaskets to shoe soles and packaging. Initially, it is crucial to note that PVC’s primary advantage lies in its availability and affordability. Among other advantages of PVC are:
High mechanical strength,
Resistance to sunlight,
High wear resistance,
Low electrical conductivity,
Flame resistance.
However, PVC has its drawbacks, including low thermal resistance, high weight and density, and the release of toxic gases in its molten state.
In contrast, TPEs constitute a diverse family of polymers that can operate at very high temperatures (e.g., 170 °C), possess special properties like thermal and electrical conductivity, and create various surface characteristics. TPEs are environmentally friendly and do not release toxic or harmful components throughout their life cycle. The benefits of this group encompass:
Excellent flexibility,
Outstanding fatigue resistance,
High impact resistance,
Excellent stability against chemical components,
Low density and lightness,
Good and cost-effective processability and formability.
However, the notable disadvantages of TPEs include their high price and aging issues, such as changing dimensions, reduced thermal resistance, creep, etc., during service.
The following tables present selected physical/mechanical properties and stability against various chemical environments for PVC and TPEs, respectively.
