Thermoplastic polyester blends

However, due to the slow rate of crystallization, PET has not been used in injection molding applications until recently [Burke and Newcombe, 1982 Hecht and Ford, 1985]. Through the use of specific types of nucleators (e.g., sodium stearate, sodium ionomers) and other crystalliza- 

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. 

The primary motivations for blending the thermoplastic polyesters with other polymers are (a) to improve the solvent resistance and process-ability of amorphous polymers such as PC, styren-ics, PPE, etc., (b) to reduce the mold shrinkage of polyesters associated with their crystallization, 

PBT/PET blends are used for making visible parts of both large and small appliances that need the appeal of smooth and glossy surface along with high stiffness, strength, and DTUL. There are also other electrical and automotive applications. Compared to the neat PBT molding resins, the market for the blend is still relatively small. 

Unmodified PBT is a fairly ductile material exhibiting high elongation at break, even after crystallization. However, as to be expected of all rigid semi-crystalline polymers, molded parts of PBT show low notched Izod impact strength indicating that under conditions of stress concentration, the 

---

As in the preceding section, the polymers to be bonded were PVC, ABS, and the thermoplastic polyester blend Xenoy. In addition microscope slide glass was also studied. Surfaces of these materials have been shown to be capable of widely differing acid-base interactions. The PVC was an unplasticised polymer (MW = 54,000 g/mol) from Synergistic Chemicals, Inc. It contained 5 phr of Advastab TM-821SP thermal stabiliser. The ABS (Cycolac AR 3501), was a moulding grade, commercial product of GE Plastics, Inc. The same source supplied the Xenoy blend the exact composition of this material was not determined. 

Polyester-silicone Polyesters, thermoplastic Polyesters, unsaturated Polyester urethanes Polyester-wool blends Polyether antibiotics Polyether carboi lates Polyether elastomers... 

Eigure 6 shows the stiffness of Ecoflex /PLA blends depending on the PLA amount. PLA today is a thermoplastic polymer made from renewable raw materials and is available on industrial scale. Blending the completely different thermoplastic polyesters - stiff and brittle PLA with soft and flexible Ecoflex - a whole range of different material properties can be accessed, depending on the ratio of both polymers. 

A wide range of thermoplastic starch compounds have been claimed in recent years. Formulations of thermoplastic starch with linear, biodegradable polyesters, including polycaprolactone and PHBV,174 176 and with polyamides175 have been reported. Laminated structures have been claimed using thermoplastic starch or starch blends as one or more of the layers.175,177,178 The use of polymers latexes as components of thermoplastic starch blends has also been claimed.179 181 Blends with natural polymers are also claimed, including cellulose esters182,183 and pectin.184 A crosslinked thermoplastic material of dialdehyde starch and protein has been reported.185... 

Mixed esters, such as isopropylphenyl diphenyl phosphate and tcrt-butylphenyl diphenyl phosphate, are also widely used as both plasticizers/flame retardants for engineering thermoplastics and hydraulic fluids.11 These esters generally show slightly less flame-retardant efficacy, when compared to triaryl counterparts however, they have the added advantage of lower smoke production when burned. Some novel oligomeric phosphate flame retardants (based on tetraphenyl resorcinol diphosphate) are also employed to flame retard polyphenylene oxide blends, thermoplastic polyesters, polyamides, vinyls, and polycarbonates. 

The decorative laminates described in the previous chapter are made with selected thermosetting resins while resins of this type can be moulded and extruded by methods similar to those outlined in the present and the next chapter the materials employed for these processes predominantly are thermoplastic. Many such plastics can be moulded and extruded under suitable conditions, the most important in terms of quantities used being those that combine properties satisfactory for the purpose with convenience in pro-cessing-especially the polyolefins (polyethylene and polypropylene), poly(vinyl chloride), and styrene polymers and blends. Other plastics with special qualities, such as better resistance to chemical attack, heat, impact, and wear, also are used—including acetals (polyformaldehyde or polyoxymethylene), polyamides, polycarbonates, thermoplastic polyesters like poly(ethylene terephtha-late) and poly(butylene terephthalate), and modified poly(phenylene oxide),... 

Reactive blending of thermoplastic starch/polymer blends has been examined recently and aims to increase properties and performance via control of blend morphologies. Mani [58, 59] examined different techniques for compatibilising starch-polyester blends. They examined development of maleic anhydride grafted polyester/starch blends and starch-g-polycaprolactone... 

In terms of nanocomposite reinforcement of thermoplastic starch polymers there has been many exciting new developments. Dufresne [62] and Angles [63] highlight work on the use of microcrystalline whiskers of starch and cellulose as reinforcement in thermoplastic starch polymer and synthetic polymer nanocomposites. They find excellent enhancement of properties, probably due to transcrystallisation processes at the matrix/fibre interface. McGlashan [64] examine the use of nanoscale montmorillonite into thermoplastic starch/polyester blends and find excellent improvements in film blowability and tensile properties. Perhaps surprisingly McGlashan [64] also found an improvement in the clarity of the thermoplastic starch based blown films with nanocomposite addition which was attributed to disruption of large crystals. 

The thermoplastic polyesters (PEST) are dominated by two resins polyethyleneterephthalate (PET) and polybutyleneterephthalate (PBT). There are similarities between ABS/PA and ABS/PEST blends. 

The thermoplastic polyesters have been often blended with amorphous polymers to improve chemical resistance and processability. Elastomers have also been added to improve their impact resistance. 

In one example, over 150 parts of a steel riding mower have been incorporated into two injection molded thermoplastic panels made from a PC/polyester blend. These are adhesively bonded to a lower fiber reinforced PU lower member. Although the plastic material cost is ten times that of the sheet metal it replaces, economies in assembly, painting and part inventory give the final product a 10% lower cost. 

Unlike the thermoplastic polyesters (PBT and PET), the commercial polyamides such as PA-6 or PA-66 are more polar and hence highly immiscible with polycarbonate. Hence simple blends of polyamide and polycarbonate are expected to delaminate readily, unless a suitable compatibiliz-er is used. Because of the lack of an efficient com-patibUization technique, blends of PA-6 (or PA-66) with polycarbonate have not yet reached a commercial significance, although there are several patents claiming improvement in properties. 

Mater-Bi (Novamont, Environmental Packaging, L. P.) Thermoplastic, compatibiUzed blends of starch with aliphatic polyesters, EVAl, PVAl,... 

During the past three decades a few groups of materials have been developed that could be considered as being in this category. Designated as thermoplastic elastomers, they include (1) styrene-diene-styrene triblock copolymers (2) thermoplastic polyester elastomers and thermoplastic polyurethane elastomers and (3) thermoplastic polyolefin rubbers (polyolefin blends). 

Traditionally, the cadmium-based pigments have been widely used in engineering resins such as the polyamides 6 and 6/6, PC, thermoplastic polyesters and their blends and alloys. 

The anthraquinone dyes are based on the structure shown in Figure 4. Key properties are summarized in Table 3. Most commercial anthraquinone dyes have sufficient heat stability to be used in polycarbonate and thermoplastic polyesters. However, as indicated in Table 3, only a handful of these dyes are suitable for polyamide Figure 4. The anthraquinone resins and their blends and alloys. Even in these cases caution must ring system. applied. Polyamide materials colored with red anthraquinone... 

Botana et al. [50] have prepared polymer nanocomposites, based on a bacterial biodegradable thermoplastic polyester, PHB and two commercial montmorillonites [MMT], unmodified and modified by melt-blending technique at 165°C. PHB/Na and PHB/ C30B were characterized by differential scanning calorimetry [DSC], polarized optical microscopy [POM], X-ray diffraction [XRD], transmission electron microscopy [TEM], mechanical properties, and burning behavior. Intercalation/exfoliation observed by TEM and XRD was more pronounced for PHB30B than PHB/Na,... 

---