Thermoplastic vulcanizate TPV

In an alternate synthesis, the formation of thermoplastic vulcanizate (TPV) is accomplished with two polymers, wherein one polymer is grafted with a carboxylic acid anhydride, which then is reacted with an aminosilane, which reacts with the acid anhydride and then cross-links with moismre. The vulcanizates exhibit good mechanical properties and lower melt-flow index than the starting polymers. 

Recent work on thermoplastic vulcanizates (TPVs) will not be included in this chapter since it is being reviewed elsewhere in the book. Abbreviations for some mbbers and accelerators will be used throughout in place of their full names as shown in Table 11.1. Acronyms for other polymers and additives wUl be provided in the text as required. A short discussion of polymer miscibility and compatibUization of polymer blends will be provided for better appreciation of the subject. 

Elastomers are often blended with plastics either to improve the impact resistance or to develop new materials having both plastic and elastic behavior. When the elastomer in the blend is dynamically vulcanized, the product is called a thermoplastics vulcanizate (TPV). Blends with unvulcanized mbber phase are usually known as thermoplastic elastomers. TPVs are discussed in another section of this book. This section will deal with recent developments in rubber-plastic blends. 

In this part, we will discuss AFM images and nanomechanical data obtained in smdies of natural and synthetic rubbers, thermoplastic elastomers (TPE), and their vulcanized counterparts— thermoplastic vulcanizates (TPV). 

Fig. 2 Compression set (elastic recovery under compressive deformation) at 70 °C for an ethyl-ene-LAO random copolymer, flexible polyvinylchloride (f-PVC) thermoplastic polyurethanes (TPUs), and thermoplastic vulcanizates (TPVs)...

The contribution of Babu and Naskar gives a comprehensive overview on the recent developments of the thermoplastic vulcanizates (TPVs) with special reference to the technological advancement. TPVs combine high volume molding capability of thermoplastic with elastomeric properties of thermoset rubber. Therefore, they land themselves to broad area of applications in various fields. 

Two important types of elastomeric polyolefin blends are reactor-made iPP/ EPR blends and postreactor blend iPP/EPDM. The latter is called thermoplastic vulcanizates (TPVs), produced by dynamic vulcanization of blends containing a thermoplastic and an elastomer. To make iPP/EPDM TPV, the two polymers PP and EPDM are mixed with curatives, such as peroxides, phenolic resins, or sulfur with accelerators, and dynamically cured in an extmder resulting in a blend consisting of micrometer-sized elastomer particles dispersed in the PP matrix (20-24). Paraffinic oils are added in the melt mixing process for viscosity control and cost. In iPP/ EPDM TPV, the crystalline iPP resin is normally the minor phase. Recently, polyolefin plastomers have been added to the class of elastomeric polyolefin blends. Polyolefin plastomers are ultralow molecular weight linear low density polyethylenes (ULMW-LLDPE). Nonelastomeric polyolefin blends are blends of polyolefins with mostly nonpolyolefin (other thermoplastic) matrices as mentioned earlier. 

DYNAMICALLY VULCANIZED PP/EPDM BLENDS (OR THERMOPLASTIC VULCANIZATES (TPVs))... 

Thermoplastic elastomer (TPE) blends have been broadly studied as a new class of materials. TPEs offer various advantages and require no state-of-the-art processing machinery, while scrap and rejects are recyclable. Blends can be homogeneous, phase separated or both. TPEs are multi-phase polymer systems consisting of hard and soft domains that can be copolymers or mechanical blends. This phase separation leads to materials having unique and viable commercial physical properties. TPEs exhibit the thermoplastic characteristics of the hard thermoplastic phase, and resilience as a result of the rubbery domains. TPEs based on natural rubber (NR) and thermoplastic blends are known as thermoplastic natural rubber (TPNR) blends. There are two types of TPNR, namely thermoplastic polyolefin (TPO) and thermoplastic vulcanizate (TPV).3... 

A thermoplastic vulcanizate (TPV), represented by the lower right quadrant of Fig. 4.38, is a TPE produced by dynamic vulcanization, the process vulcanizing a vulcani-zable elastomer during its intimate mixing with a thermoplastic polymer in the molten state. A TPV comprises finely divided particles of highly cross-linked rubber in a continuous matrix of rigid thermoplastic. 

Thermoplastic Vulcanizates (TPVs). TPVs differ from TPOs in that the mbber phase is highly vnlcanized (cross-hnked). This phase of a TPO has little or no cross-hnk-ing. As a resnlt, the properties and performance of a TPV are much closer to those of a... 

Thermoplastic Vulcanizate (TPV). TPVs are generally classified as f-TPV and p-TPV, wherein the prefixes indicate fully and partially vulcanized, respectively. Compounds of f-TPVs are typically made with EPDM and PP. In few special TPV compounds, EPDM is replaced by nitrile rubber, and natural rubber as well. The industry benchmark is TPV compounds, and they are sold under the trade name of Santoprene and marketed by Advanced Elastomer Systems (AES) Ltd. Mitsui is also dominant in the TPV based interior skins market in Europe. Seventy-five to 90 percent of TPV compounds are fully cross-linked with EPDM and are priced at approximately 1.80/lb. Two to 10 percent are par-... 

EPDM-PP thermoplastic vulcanizates (TPVs) provide cost-effective durable sealing performance, with resistance to UV light, ozone, heat, and chemical... 

Thermoplastic vulcanizates (TPVs) typically contain 60-70 % EPDM and 30-40 % impact polypropylene. These products contain a low level of crosslinks, but they are true thermoplastic materials. TPVs have superior strength, high-temperature mechanical properties, hot oil and solvent resistance, and better compression set than partially cured material. These materials are almost always dynamically cured, which refers to the process whereby the rubber phase is vulcanized during melt mixing with the molten non-cross-linked plastic. 

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