The Effects of Processing on Thermoplastics

Da Roz A.L., Carvalho A.J.F., Gandini A., Curvelo A.A.S. The effect of plasticizers on thermoplastic starch compositions obtained by melt processing, Carbohydr. Polym. 63 (2006) 417. 

Consolidation/Fiber Motion Submodel The consolidation and fiber motion submodels evaluate the effects of processing conditions on the interaction between plies. In particular, the consolidation submodel (for thermoplastics) models the bonding between composite plies. The fiber motion submodel (for thermosets) yields the fiber position and fiber volume fraction within the cylinder. 

In this article, recent developments in the formation and properties of epoxy layered silicate nanocomposites are reviewed. The effect of processing conditions on cure chemistry and morphology is examined, and their relationship to a broad range of material properties elucidated. An understanding of the intercalation mechanism and subsequent influences on nanocomposite formation is emphasized. Recent work involving the structure and properties of ternary, thermosetting nanocomposite systems which incorporate resin, layered silicates and an additional phase (fibre, thermoplastic or rubber) are also discussed, and future research directions in this highly active area are canvassed. 

The co-continuous structure and the final rheological properties of an immiscible polymer blend are generally controlled by not only the viscoelastic and interfacial properties of the constituent polymers but also by the processing parameters. For example, the effect of plasticizer on co-continuity development in blends based on polypropylene and ethylene-propylene-diene-terpolymer (PP/EPDM), at various compositions, was studied using solvent extraction. The results showed more rapid percolation of the elastomeric component in the presence of plasticizer. However, the same fuUy co-continuous composition range was maintained, as for the non-plasticized counterparts (Shahbikian et al. 2011). It was also shown that the presence of nanoclay narrows the co-continuity composition range for non-plasticized thermoplastic elastomeric materials (TPEs) based on polypropylene and ethylene-propylene-diene-terpolymer and influences their symmetry. This effect was more pronounced in intercalated nanocomposites than in partially exfoliated nanocomposites with improved clay dispersion. It seems that the smaller, well-dispersed particles interfere less with thermoplastic phase continuity (Mirzadeh et al. 2010). A blend of polyamide 6 (PA6) and a co-polyester of... 

It has been observed that the crystallization behavior of polymers is modified when the material is strained. This behavior has been found in rubbers and in thermoplastics [14]. In thermoplastics, the effect of strain on crystallization behavior has been studied quite extensively in solutions, in melt, and in solid state. For instance, it has been found that flowing polymer melts can crystallize at temperatures that are substantially above the crystallization temperature of the same material in a quiescent state. This strain-induced crystallization is generally explained in terms of thermodynamic processes. During a phase change, the Gibbs free energy is ... 

Block copolymer systems have aroused interest with reviews of the synthesis of nylon elastomers, thermoplastic polyether-polyamide elastomers, and thermoplastic cross-linked polyamides of 3,3 -bis(hydroxymelhyl) glutaric add. Block copolymers were also reported from poly(/n-phenylene isophthalamidc) and poly(ethylene oxide) or poly(dimethylsiloxane). The polycondensation of oco -dicarboxylic-poly(amide 11) and x -dihydroxy-polyoxyethylene has also been studied and rate constants and activation energies evaluated for the process. The polycondensation of axo -diacid and e9o> -diester-poly(amide 11) oligomers with cuco -dihydroxy-polyether oligomers has similarly been reported. Lactam Rli -opening Polymerization Routes.—The effects of ring size, substitution and the presence of heteroatoms on the polymerizability of lactams has been the subject of reviews. - In the field of lactam polymerization, two systems have evoked major interest, namely caprolactam and 2-pyrrolidone. Studies on caprolactam have reported the effect of water on the mechanism of polymerization and polymerization rate, where it was found that the process was... 

Thermoplastic elastomers (TPEs), which combine the elastic response like rubber vulcanizates with the processability of thermoplastics, are becoming one of the industrially important polymeric materials [60-62]. The morphology control by processing conditions is a key issue to improve mechanical properties of TPEs. Therefore, the effects of processing conditions on morphology and microscopic mechanical properties ofpoly(styrene-fe-ethylene-co-butylene-fc-styrene) (SEES) triblock copolymer, one of the most widely used TPEs, is investigated by nanomechanical mapping [45]. 

---