Torque rheometry

Torque rheometers are multipurpose instruments well suited for formulating multicomponent polymer systems, studying flow behavior, thermal sensitivity, shear sensitivity, batch compounding, and so on. The instrument is applicable to thermoplastics, rubber (compounding, cure, scorch tests), thermoset materials, and liquid materials. 

When the rheometer is retrofitted with a single-screw extruder one can measure rheological properties and extrusion processing characteristics to differentiate lot-to-lot variance of polymer stocks. It also enables the process engineer to simulate a production line in the laboratory and to develop processing guidelines. 

Melt Temp 190 °C Press Tran 1000 Bar Capillary 30/1L/D Press Instblty X Melt Fracture  

The torque rheometer with a twin-screw extruder is considered a scaled-down continuous compounder. It allows the compounding engineer to develop polymer compounds and alloys. It also permits the formulation engineer to assure that the formulation is optimum. 

The torque rheometer is essentially an instrument that measures viscosity-related torque caused by the resistance of the material to the shearing action of the plasticating process. 

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Parker MD, Rowe RC, Upjohn NG. Mixer torque rheometry a method of quantifying the consistency of wet granulations. Pharm Technol Int 1990 2 50-62. 

Figure 13. Application of torque rheometry to studying extrusion operations.

VISCOSITY CHANGES ASSOCIATED WITH THE CHEMICALLY INDUCED CROSSLINKING OF PLASTICISED POLYVINYL CHLORIDE MEASURED BY PARALLEL PLATE TORQUE RHEOMETRY INFLUENCE OF MAGNESIUM AND BARIUM MERCAPTIDES Rosales-Jasso A Arias G Rodriguez O S Allen N S Centro de Investigacion en Quimica Aplicada Manchester,Metropolitan University... 

Rowe, R.C. Parker, M.D. Mixer torque rheometry an update. Pharm. Tech. 1994, 74-82. 

SEM / selective solvent extraction / FTIR / DMTA / WAXS thermal redistribution in internal mixer at 260°C / NMR / TLC / DSC internal mixer at 240°C / torque rheometry / SEM / GPC / mechanical properties / effects of mixing time / effects of PA amine and acid end-group concentrations internal mixer at 240°C / selective solvent extraction /... 

PA-6 (100-75) / EDPE (0-25) / LDPE-g-BA (18% BA) (0-2.4) internal mixer coupled to SSE at 260°C / SEM / torque rheometry / mechanical properties / water absorption / hardness / effect of premixing EDPE + EDPE-g-BA Raval etal., 1991... 

Favis [1994] and Willis andFavis [1988] prepared compatibilized PA blends with PP and carboxylic acid-functionalized EMAA ionomer. Blends containing 90-10 parts PA-6, 0-30 parts EMAA ionomer, and 10-90 parts PP were combined in an internal mixer at 250°C and characterized by torque rheometry and SEM. Dispersed phase particle size vs. interfacial modifier concentration was determined. Emulsification curves were constructed. Effects of mixing protocol on blend properties were studied. Blends were also prepared containing HOPE in place of PP. 

PA-6 (85-75) / SAN (25% AN) (12-25) / imidized acrylate copolymer (56% methyl glutarimide, 40% MMA, 2% MAA, 3% glutaric anhydride) (0-8) TSE at 240°C / torque rheometry / SEM / morphology development in extruder vs. screw design and processing conditions / also PA-6 and PA-66 blends with SEBS-g-MA / titration of residual amine end-groups Majumdarcta/., 1997... 

PA-6 (80-70) or PA-66 / SMA (0-10) / SB core + MMA shell impact modifier (20) or BA core + MMA shell SSE at 240-280°C / torque rheometry / mechanical properties / ductile-brittle transition temperatures / TEM / effects of mixing protocol Lu etal., 1996, 1993... 

PA-6 (100-0) / ABS (0-100) / imidized acrylate copolymer with various acid + anhydride concentrations (0-20) SSE at 240°C / TEM / torque rheometry / mechanical properties vs. compatibilizer content, functionalization level, rubber cone, and mixing protocol / ductile-brittle transition temperatures Majumdar et al., 1994 b... 

PA-12 or PA-1212 or PA-612 or PA-610 or PA-69 or PA-46 /SEES (0-20) / SEBS-g-MA (1.8% MA) (0-20) properties / TEM / ductile-brittle transition temperatures / interfacial tension estimates / effects of PA amine end-group concentration on copolymer formation (titration before and after extrusion) / torque rheometry ... 

Amorphous PA (20) / S-IPO (1% IPO) (80) internal mixer at 200°C / torque rheometry / selective solvent extraction / SEM study of morphology development in reactive and in non-reactive blends Scott and Macosko, 1995... 

FTIR / DSC / DMTA / mechanical properties internal mixer at 200-250°C torque vs. time, temperature / DSC / DMA / improved modulus and tensile strength as copolymer forms internal mixer at 230, 250, or 270°C / torque rheometry / DSC / mechanical and thermal properties SSE at 265-270°C / thermal redistribution during molding at 270-320°C / DMA... 

PET (50) or PETG / E-GMA (6% GMA) (50) internal mixer at 270°C / torque rheometry / GPC / effects of residual levels of different catalysts used to synthesize polyesters Stewart et al., 1993b... 

Vainio et al. [1997, 1996a] have compatibilized PEST/PP blends by graft copolymer formation between acid-terminated polyester and oxazo-line-grafted PP. Specifically, 30 parts PBT was mixed with 0-70 parts PP and 0-70 parts PP-g-oxazoline in an internal mixer at 250°C or TSE at 240°C. Blends were characterized by SEM, torque rheometry, DMA, and DSC. Oxazoline-functionalized PP was prepared by grafting PP... 

TSE at 260°C / mechanical properties / SEM / DSC / torque rheometry / DMA / ethyltriphenyl phosphonium bromide catalyst (0-0.05 parts)... 

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