Difference between TPV and TPO - Thermoplastic polymers, elastomers and additives

All TPE consist of crystalline and amorphous domains. Some are mixtures or alloys (eg TPO and TPV) of crystalline and amorphous polymers; some are block copolymers (eg, SBS, SEBS) block comprising crystalline and amorphous domains along the same polymer chain. The crystalline domains act as TPEs and give their thermoplastic character "crossed heat fugitive bonds." Amorphous domains grant them their elastomeric character. The crystalline domains are typically referred to "hard" phase and the amorphous domains of the "soft" phase. A key feature of this family of materials is their ability to provide some of the physical characteristics associated with thermoset rubbers. In milder degrees of hardness,The morphology of co-continuous phase and the lack of crosslinking the EPDM give the TPO properties of strength and elongation at room temperature greatly improved compared to a TPV equivalent hardness. In the harder Shore D range, the TPO becomes clearly more similar to plastic deformation; in these hardnesses, the rubber content is reduced and has a significantly lower impact on any reaction to the applied voltages.

In the transformation of TPO and TPV is no substantial improvement in desirable properties such as elastic recovery (compression set, tension set) and tensile strength elastomeric physical properties. This is counterintuitive, since the compatibility between the rubber and the plastic should decrease the rubber crosslinking and result in poorer properties compared to TPV corresponding TPO. The observed properties of the TPV can be explained if the rubber particulate is firmly anchored in the amorphous part of the plastic phase. The change of hardness in the transformation of TPO TPV is dependent upon the change in product morphology and crystallinity in the plastic phase, also due to crosslinking of the rubber phase.In the TPV, the homogeneous distribution of discrete rubber particles allows the material to exhibit more rubbery behavior. A key attribute associated with the rubber materials is their ability to recover from an imposed load. This is especially necessary in the sealing area and stretching under a variety of conditions. The TPO materials, although they are flexible, have good recovery properties. Both the lack of crosslinking in the rubber phase is combined with the flow behavior of PP causes a permanent and irretrievable "set" in the material even at room temperature. This precludes its use in many areas of sealing and other applications where recovery of the applied load is important. The discrete rubber particles in the comparative TPV cause a drop in tear resistance compared to TPO but only under ambient conditions. The TPV continues to provide acceptable tear resistance even at elevated temperatures. Flex fatigue TPV is an excellent yield higher than chloroprene, EPDM rubbers and chlorosulfonated termosesta. The thermal properties of TPO and TPV for example the point of low temperature brittleness is comparable between the POS and the soft TPO, but the strongest influence of the PP phase hard TPO significantly raises the brittle point. Although not shown, the performance of low temperature impact is good for both TPO and POS. Due to the lack of crosslinking of the rubber in the TPO material the upper service temperature is limited. The melting temperature has a much smaller influence on the flow in TPO TPV. Comparing a standard grade TPO TPV, one can observe that the TPO having a viscosity lower melt flowability and higher melt. Both TPO and TPV show thinning behavior linear cutting in melting condition. Is possible to generate speed values ​​MFR melt flow for TPO but due to the different rheological characteristics of TPV, it is not possible to achieve a value of MFR consistently repeatable. Both TPO and TPV show thinning behavior linear cutting in melting condition. Is possible to generate speed values ​​MFR melt flow for TPO but due to the different rheological characteristics of TPV, it is not possible to achieve a value of MFR consistently repeatable. Both TPO and TPV show thinning behavior linear cutting in melting condition. Is possible to generate speed values ​​MFR melt flow for TPO but due to the different rheological characteristics of TPV, it is not possible to achieve a value of MFR consistently repeatable.

The influence of heat aging in the TPV is largely independent hardness. The heat resistance is related to the chain structure both saturated as completely cured EPDM PP. In periods of time greater than the upper service temperature recommended (135 ° C), in this case 150 ° C, the yield strength decreases and this is attributable to the-thermo-oxidative polymer degradation arising from volatilization antioxidants and oil oxidation process.

The inherent chemical resistance is very good throughout the range of hardness, the reason is the chemical resistance provided by the continuous phase of PP EPDM particles. As expected, this type of POS is resistant to polar solvents nature and, to a lesser extent, non-polar solvents. The degree of swelling is also reflected in the proportion of EPDM present in a particular degree, the softer the grade, the higher the content of EPDM, therefore, less PP and increased susceptibility to swelling.