Thermoplastic elastomers, more often known as TPEs, are widely regarded as one of the most adaptable types of plastic material.
These hybrid thermoplastic materials offer a greater range of service properties with highly flexible elastomer characteristics and mechanically stable structural properties of thermoplastic polymers.
The versatility of thermoplastic elastomers (TPEs) with cost optimisation and design characteristics have made thermoplastic elastomers (TPEs) a very suitable material to be used for the applications of automotive, electronics, medical devices etc., which are covering thousands of products being used in our daily life for essential purposes.
However, since late 1970, liquid silicone rubber (LSR) has gained much attention. Liquid silicone rubber (LSR) is frequently found in various silicon-based goods, small components, and accessories.
The mechanically and thermally stable structure of Liquid silicone rubber (LSR) distinguishes its high-quality performance with flexible injection molding settings, allowing it to be selected above any other thermoplastic, rubbery materials or elastomers.
Liquid silicone rubber (LSR) is mainly processed for the applications of end-use consumer products, medical devices, automotive and specialised heavy-duty industrial products.
Liquid silicone rubber (LSR) offers greater flexibility with wear-free optical properties making it able to be used in medical optics.
Properties & Applications of Liquid Silicone Rubber (LSR)
These days, liquid silicone rubber, often known as LSR, is widely regarded as having outstanding optical and aesthetic properties. The unique characteristics of silicon rubber, an inorganic polymeric substance composed of carbon, hydrogen, and silicon, are included in liquid silicone rubber (LSR).
The main chain of silicon rubber mostly comprises oxygen and silicon, known as siloxane. The main backbone chain of silicon rubber is cured by incorporating a catalyst with a complete processing method to get the desired end properties of silicon derivative material.
The curing of silicon rubber may be done using peroxide or platinum. This curing forms crosslinking networks offering stiff and flexible properties for the final product. Liquid silicone rubber (LSR) is mostly cross-linked by using platinum.
The curing done with platinum offers greater mechanical and tear strength with improved optical and thermal consistency. Furthermore, the residue of peroxides is another disadvantage of using peroxide for curing Liquid Silicon Rubber (LSR).
Liquid Silicon Rubber (LSR) injection moulding is a very efficient process. This material allows easy processing and high machinability with greater production rate, quality, consistency, and productivity with lower troubleshooting events.
Considering the properties of LSR, this material has made itself a very excellent material for a wide range of applications.
Some of the properties are as hereunder:-
1. The resistance of Liquid Silicon Rubber (LSR) towards bacterial cultures is very good, and they oppose their growth. LSR is also a non-corrosive or non-stain material.
The compatibility of Liquid Silicon Rubber (LSR) with human tissues, cells, body fluids or substances is admirable. This property makes it a suitable material for skin care-oriented medical products.
2. They are odourless, even if they don’t offer any taste, so they may be formulated for the applications of food or beverage industries and baby products. Liquid Silicon Rubber (LSR) also offers FDA compliance characteristical properties.
3. The products of this material are thermally and mechanically stable. They are stable even at elevated temperatures, and this property makes them considerable material for indoor or outdoor applications in the automobile industry.
4. The durability of Liquid Silicon Rubber (LSR) is also because of its strong stabilised structure. They highly resist the cause of their structural change. They are highly resistant to alkalis, acids, water, chemical solutions, and oxidising agents.
Liquid Silicon Rubber (LSR) sterilisation is common and frequently used in medical devices and products.
5. These materials are more durable and thermally stable even for a vast range of temperatures when injection moulded at specific process parameters.
Compared with other rubbery or elastomeric materials, Liquid Silicon Rubber (LSR) can withstand the lowest to elevated temperature ranges. The thermal endurance of these materials is from -60oC to 180oC.
6. The optical characteristics of Liquid Silicon Rubber (LSR) allow them to be used as translucent material. The inherent white colour of silicon naturally allows them to be dyed or pigmented, making them aesthetically appealing and attractive.
This versatile range of pigmentation makes this material dominant for multipurpose or multi parts product applications.
7. The hardness of Liquid Silicon Rubber (LSR) is presentable, i.e. 5 to 80 with the Shore A hardness measuring technique. Apart from it, the mechanical, tensile and tear of LSR are also very good, making it more flexible and adaptable to changes in conditions surrounding it.
8. The electrical performance of these materials is linked to their thermal properties. Due to high thermal stability, they possess very efficient insulating characteristics for extreme temperatures.
This stabilised insulation makes them able to be used for electrical applications.
Advantages of Liquid Silicone Rubber (LSR)
1. This advanced hybrid Liquid silicone rubber (LSR) allows product manufacturers to produce a cost-efficient, optimised and high-quality product with a greater production rate, high precision and accuracy even for complex injection moulding products.
2. Many of the moulding products of plastics are done using compression moulding, which involves the interaction of labour with product processing, also known as labour-intensive moulding.
Liquid silicone rubber (LSR) injection moulding is usually done with automated computer-assisted machines. These machines eliminate the chance of error, irregularity, shape abnormality, shrinkage and aesthetical disorders in the final moulded product.
3. The overall cycle time for material processing is very important. A small variation in this time may cause degradation and, ultimately, a huge loss.
Some factors, including mould temperature, state of melt in mould, design of the mould, cooling time, vulcanisation parameters and properties of the material, are considered highly for injection moulding of Liquid silicone rubber (LSR). The curing of material is a key factor for finalising end-use product characteristics.
Curing time is also a part of cycle time, so it is adjusted accordingly with greater optimisation. Using platinum for curing may offer an efficient cycle time followed by efficient barrel pre-heating and a cold runner cooling system utilisation.
An efficient cooling system and automated moulding machine lessen or ideally eliminates the waste and scrap even for the material of runners.
4. Furthermore, automation for the injection moulding of Liquid silicone rubber (LSR) allows for greater safety as it removes the presence of unwanted machine operators from the process site, reducing the risk of any harmful event or practice.
Automated removal of products from mould and their transportation further streamline and ensure the safety of the human workforce.
Properties & Applications of Thermoplastic Elastomer (TPE)
Thermo Plastic Elastomer (TPE) combines thermoplastic and highly vulcanised thermoset characteristical properties. The thermoset rubbery part provides a very high elasticity at ambient temperature.
In contrast, the other hand thermoplastic part of Thermo Plastic Elastomer (TPE) presents greater machinability for elevated ranges of temperature. Crosslinking is the key factor in determining the material’s elastic properties.
The type of crosslinking bond is the main factor differentiating a thermoplastic elastomer and a thermoset elastomer.
Thermo Plastic Elastomers (TPE) are synthesised and designed with greater cross-linking optimisation, ensuring the required curing and viscous properties and presentable elastic properties to make a final, hybrid, modified, chemically stabled, and compounded low-cost product.
If you are dealing with a thermoplastic elastomer (TPE), you must consider the following properties of the material for the required results:
1. The material’s elasticity level should follow the proportionality and elastic limit before yielding to accommodate the elastic properties in the final product. An elastic nature always attracts the consumer.
2. The temperature ranges for the process should be vast, especially for elevated temperature values.
3. The creep of the material should be low for high durability and performance. In terms of cost and performance, thermoplastic elastomeric materials are among the more affordable options, outperforming conventional silicon rubber, PVC, and latex-based materials.
Its properties are similar to rubber and are considered for their utilisation as an alternative material for the applications of shoes, automobiles, daily household products and medical devices.
Thermoplastic elastomers are the most usually thought of among recyclable materials due to their resemblance to thermoplastic materials in terms of their characteristics.
But at the same time, the thermoset nature of Thermo Plastic Elastomers makes them highly unfit for recycling, making the recycling process more difficult and complex.
Furthermore, the dominant properties of Thermoplastic Elastomer (TPE) are presented below:
4. Stiffness, Young’s modulus, hardness, impact strength, toughness, abrasion resistance and tear resistance are considered high during the composition or formulation of a specific Thermoplastic Elastomer. A high range of temperatures allows these materials to be versatile for above mentioned mechanical properties above ambient temperature till the value of their softening temperature. This hard phase is very important to retain for the finalisation of the end properties of products.
5. The soft phase of the thermoplastic elastomer represents the flexibility of this material, which is due to elastomeric or rubbery elongation.
This flexibility also ensures the material’s dynamic properties, low-temperature stability, flexure, and tensile strength. However, the tensile strength is linked with the crystallisation of chains in the material.
Heat-assisted strain induces crystallisation and may improve the tensile strength, improving the material’s mechanical properties.
6. The degree or level of polarisation is crucial in covering the electrical properties, especially for thermoplastic elastomers.
The insulation properties may be acquired with minimum polarisations. Several thermoplastic elastomers present excellent insulation properties being non-polar substances, including olefins and vinyl compounds.
Furthermore, the attachment of functional groups with these non-polar compounds and the type and properties of attached functional groups are also very important in determining the final electrical properties of materials.
7. The thermal characteristics of polymers are very important for their higher performance. Thermoplastic Elastomers opt for various high-temperature applications as they possess high thermal performance, processability and melt processing.
These materials’ glass transition temperature (Tg) is higher, which controls the material’s mechanical properties above ambient temperature. Higher mechanical strength is necessary for flexibility and higher loading applications.
The soft thermoplastic phase controls the brittleness of the thermoplastic elastomer.
8. The chemical resistance of thermoplastic elastomers is highly dependent on the functional groups attached to their backbone chains. The presence of non-polar functional groups with the chains always prevent and avoid linkage with chemical, ultimately improving their chemical resistance.
On the other hand, polarised groups exhibit low chemical resistance. Olefins and vinyl-based chains are mostly non-polar and show a very high chemical resistance compared to other thermoplastic materials.
However, the amorphous non-polar thermoplastic elastomers possess very low resistance to chemicals.
9. The environmental impact or outdoor resistance is very important. These materials have stabilised structure and morphology, offering excellent environmental resistance properties.
That is the reason they are highly beneficial for applications in the automotive industry.
10. Thermoplastic Elastomers are counted as the finest materials for injection moulding because of their high production rate, processability, productivity and almost no material wastage.
Due to these appealing properties, these materials are used in manufacturing hoses, tubes and many daily household quality products. These materials are also used for multi parts products or insertions.
Advantages of Thermoplastic Elastomer (TPE)
1. Thermoplastic Elastomers (TPEs) are very simple to process, offering a very energy-efficient process, ultimately reducing the cost of the overall process.
2. They offer very low cycle time because of easy processing, with high productivity and production rate optimising the end profits.
3. The formulation of these materials is very simple to adjust and optimise. TPEs are versatile materials and offer very good properties even with small variations, adjustments or tuning of process parameters.
Olefins such as Poly Ethylene (PE) or Poly Propylene (PP) are mostly opted for because of their flexible nature. These materials even dint require any additives to optimise the final product properties but in specified conditions.
4. The mechanical properties of these materials are very good. Complete optimisation may cover a range of hardness, resulting in different grades of these materials per their hardness value.
5. The electrical properties are highly dependent on the thermal environment. They have good insulation properties, but the temperature of softening point as higher temperature causes polarisation inside the material leading to the support for the flow of charges, ultimately weakening the insulating properties.
The selection of material between Liquid Silicon Rubber and Thermoplastic Elastomer is quite challenging as they possess many similar properties, including flexibility, mechanical strength, chemical resistance, electrical insulation etc.
But some deciding factors may affect your selection for a particular application. Liquid Silicon Rubber has extremely high optical characteristics compared to Thermoplastic Elastomers, which may be utilised for translucent and transparent applications.
While on the other hand, Thermoplastic Elastomers possess good pigmentation properties.
The melting point of Liquid Silicon Rubber ranges from 180oC to 450oC, presenting very high thermal stability even at elevated temperatures compared to Thermoplastic Elastomers, whose melting point ranges approximately from 150oC to 170oC. So, the temperature range of Thermoplastic Elastomers is also very low, below their softening temperature.
This structural stability governs the material’s mechanical, electrical and morphological properties.
Furthermore, the performance of products made from silicon and thermoplastic elastomers is very great. Both materials are durable, long-lasting, truthful, flexible and mechanically stable.
However, Liquid Silicon Rubber offers more aesthetically great products than Thermoplastic Elastomer. Thermoplastic elastomer’s chemical resistance is higher because of non-polar structures or functional groups than liquid silicon rubber.
The liquid silicon rubbers also have good chemical resistance but are not presentable for organic solvents. So, thermoplastic elastomers may be used for better performance for applications involving direct contact of chemicals with the product.
The productivity of both materials is high, but the thermoplastic elastomers provide an option for recyclability, eliminating the risk of wastage. This also contributes to uplifting the profits and lowering the overall production cost.
So, conclusively, liquid silicon rubbers may be considered with a minor compromise of the cost factor for higher thermal stability, structural stiffness, elongation, aesthetics and transparency.
However, thermoplastic elastomers may be preferred for cost-efficient selection with greater chemical resistance, resilience, toughness, strength, flexibility and recyclability.
Kemal Plastic Injection Moulding provides the best material guide for end-use applications.
Moreover, how these materials may be processed to get your desired results also falls under the supervision of our Organization. Considering liquid silicon rubber and thermoplastic, our injection moulding services may lead you to efficient productivity with greater profitability.
If you are looking for a chemical-resistant, recyclable, energy and cost-efficient material, thermoplastic elastomer is the best option. Liquid Silicon Rubber may be our best material for injection moulding products where high transparency, aesthetics, thermal stability, and durability are required.
You don’t need to worry; with the help of our professionals, you will get expert advice to choose the most suitable Modified Thermoplastic Hybrid Material for your particular requirements.