And melt rheology

Suspension- and emulsion-polymerized PVDF exhibit dissimilar behavior in solutions. The suspension resin type is readily soluble in many solvents even in good solvents, solutions of the emulsion resin type contain fractions of microgel, which contain more head-to-head chain defects than the soluble fraction of the resin (116). Concentrated solutions (15 wt %) and melt rheology of various PVDF types also display different behavior (132). The Mark-Houwink relation (rj = KM°-) for PVDF in A/-methylpyrrohdinone (NMP) containing 0.1 molar LiBr at 85°C, for the suspension (115) and emulsion... 

Epoxidized oils were also used to modify PLA Ali et ah (2009) reported that its use as a plasticizer to improve flexibility. Thermal and scanning electron microscope analysis revealed that epoxidized soybean oil is partially miscible with PLA. Rheological and mechanical properties of PLA/epoxidized soybean oil blends were studied by Xu and Qu (2009) Epoxidized soybean oil exhibited a positive effect on both the elongation at break and melt rheology. Al-Mulla et al. (2010b) also reported that plasticization of PLA (epoxidized palm oil) was carried out via solution casting process using chloroform as a solvent. The results indicated that improved flexibility could be achieved by incorporation of epoxidized palm oil. 

Experimental data on the solution properties and melt rheology of highly branched structures are scarcely found in the literature. This might be because of the structural nonuniformity of hyperbranched polymers, which makes it difficult to obtain reliable data. Because of the purely statistical nature of the poly-... 

S. S. Ray, K. Yamada, M. Okamoto, and K. Ueda, New polylactide-layered silicate nanocomposites. 2. Concurrent improvements of material properties, biodegradability and melt rheology, Polymer 44, 857—866 (2003). 

A major drawback to the industrial use of fire-retardant fillers is the high addition levels needed in most polymers to confer adequate fire retardancy. This can detrimentally influence processability and melt rheology, and, when used in load-bearing situations, the presence of the filler generally... 

Random copolyesters based on bromoterephthalic acid, methyl hydroquinone, and hexane diol have been synthesized. Their mesophase properties were studied by differential scanning calorimetry, optical microscopy, realtime X-ray diffraction and melt rheology. At low molecular weight these copolymers exhibit triphasic behavior, where two mesomorphic phases coexist with an isotropic phase. Fractionation based on solubility in THF enables the identification of two components. Simple statistical arguments are employed to model the polymerization reaction and account for the observed phase behavior. 

II. Concurrent improvements of material properties, biodegradability and melt rheology. Polymer 2003, 44, 857-866. 

Dynamic mechanical and melt rheological properties of sulfonated poly(butylene succinate) ionomers. Polymer, 44, 7165. 

The melting is the most difficult aspect due to the very low thermal conductivity of polymers. The melting depends on the thermodynamic and melt rheological properties of the polymer, and also the processing conditions such as temperature, speed and pressure, and the size and design of the screw. 

Injection pressure is a fimction of flow length, wall thickness, and melt rheology, and it is calculated to achieve uniform mold filling. The Arnitel injection pressure range is <5000 to >20,000 Ib/in (<34 to >137 MPa). Thermoplastic elastomers may not require back pressure, and when back pressure is applied, it is much lower than for thermoplastics that are not elastomeric. Back pressure for Amitel is about 44 to 87 Ib/in (0.3 to 0.6 MPa). Back pressure is used to ensure a homogeneous melt with no bubbles. 

Some of the early examples describing covalent main-chain macromolecules with UPy units attached include copolymers based on poly(l-hexene) 11 and poly (alkyl methacrylate) 12, reported by the groups of Coates and Long, respectively (Figure 12). In the latter example, tensile testing and melt rheology were used to show that the extent of interchain interactions (physical cross-links),... 

Das S, et al. Structure-property relationships and melt rheology of segmented, nonchain extended polyureas effect of soft segment molecular weight. Polymer 2007 48(1) 290-301. 

Dilute solution viscometry and melt rheology are fundamental techniques for characterizing polymeric materials. Given PLA s growing importance, it is important to understand the fundamental chain properties that are reflected in the data obtained using these experimental methods. 

The effect of short-chain (LLDPE) and long-chain (LDPE) branching in PE alters the physical and mechanical properties and melt rheology. For the same density, LLDPE has a higher melting point, tensile strength and flexural modulus. Because film is the major outlet for LDPE, this means that thinner film (down-gauging) and hence less material can be used for comparable applications. However, because LLDPE is stiffer, heavy-duty sacks are still made of LDPE. 

Prasantha Kumar, R., Manikandan Nair, K.C., Thomas, S., Schit, S.C., and Ramamurthy, K. (2000) Morphology and melt rheological behaviour of short-sisal-fiber-reinforced SBR composites. Compos. Sci. Technd., 60, 1737-1751. 

From the fundamental point of view, a multitude of studies on polyolefin blends have been reported in literature binary blends of LDPEl/HDPE and LDPE or HDPE mixed with PP, polyvinylchloride, PS, etc. as well as ternary mixtures of LDPE/HDPE/PP have been examined. Several aspects have been investigated, such as crystallization and melting, rheology, mechanical properties and morphology. Since polyolefins represent the large majority of pol3rmers in the plastic wastes, some of the above works were specifically focussed on the... 

Liebscher M, Tzounis L, Pbtschke P, Heinrich G. Influence of the viscosity ratio in PC/SAN blends filled with MWCNTs on the morphological, electrical, and melt rheological properties. Polymer 2013 54 6801-8. 

Sinha Ray S, Okamoto K, Okamoto M (2006), New poly(hutylene succinate)/ layered silicate nanocomposites. 3. Materials properties and melt rheology , JAppl... 

---