Unfilled PBT

PBT unfilled 30% glass-filled PBT 30% glass-filled PCT 30% glass-filled PCTA PET unfilled 30% glass-filled PET PETG unfilled PCTG unfilled... 

DSM s range of PBT resins and compoimds are sold under the Amite trade name. PBT products include standard PBT unfilled, 10%, 15%, 30% glass reinforced, toughened PBT with 0%, 20%, 30% glass reinforced and low warpage, 20% and 30% glass reinforced. 

TABLE 2.11 Typical Properties of Unfilled Polyethylene terephthalate) (PET), Poly(trimethylene terephthalate) (PTT), and Poly(butylene terephthalate (PBT) Solid-State Polyester Resins... 

Figure 8.1 shows dynamic mechanical analysis (DMA) data for an unfilled and 30 % glass-filled PBT. Note the sharply higher modulus ( ) in the glass-filled blend at all temperatures. 

Figure 8.1 Comparison of DMA data obtained for 30 % glass-filled and unfilled PBT samples...

Similar PET-PC and PBT-PET-PC blends have been developed in unfilled, glass-filled and mineral-filled versions. One can begin to see how all of the building blocks of PBT formulation can be used interchangeably to tailor product performance. 

Mechanical Properties. Properties of typical grades of PBT, either as unfilled neat resin, glass-fiber filled, and FR-grades, are set out in Table 8. This table also includes impact-modified grades which incorporate dispersions of elastomeric particles inside the semicrystalline polyester matrix. These dispersions act as effective toughening agents which greatly improve impact properties. The mechanisms are not fully understood in all cases. The subject has been discussed in detail (171) and the particular case of impact-modified polyesters such as PBT has also been discussed (172,173). 

Resonators and air ducts can be manufacmred by blow molding, and therefore require excellent melt strength, good surface appearance, low weight and excellent noise reduction (damping). Eor these applications, unfilled alloys such as PPE/PA are often used. Table 13.4 summarizes the property profile of typical PBT/PC and PPE/ PA blends used in under-hood applications. For comparison, these data are normalized to the performance of PBT/PC in Figure 13.2. 

Hence PBT is more commonly employed in the formulation of blends also. PBT has generally been preferred over PET in the engineering plastics industry because of its superior process-ability, faster crystallization rate, shorter molding cycles and better properties (DTUL/impact balance) in the molded parts, particularly in the unfilled form. Nevertheless, PET is also used primarily in glass or mineral reinforced form along with nucleators and crystaUization promoters. 

Example 15.6 Comment on the relative melting points as well as the impact strength and water absorption of unfilled PET and PBT. 

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