A Review of Fiber-Reinforced Injection Molding: Flow Kinematics and Particle Orientation

The existing flow and particle orientation models applicable to fiber- reinforced injection molding are reviewed. After a brief description of injection molding, previous studies on the flow kinematics and fiber reinforcement are presented. Basics of Hele-Shaw flows are described Including the commonly used viscosity models and foun tain flow effects. Some of the existing models for particle orientation are analyzed with particular emphasis on the amsotropic description of the material system. Concentration regions for short fiber suspensions are defined and relevant constitutive equations are dis cussed. A few example solutions are also given which describe the three-dimensional ori entation field for the filling of a sudden expansion cavity, depicting skin-core orientation structure.Yeshttps://us.sagepub.com/en-us/nam/manuscript-submission-guideline

Process parameters estimation for structural reaction injection molding and resin transfer molding

Some design strategies for structural reaction injection molding (S-RIM) and resin transfer molding (RTM) are presented. Our approach makes use of moldability diagrams to define the parameters necessary to meet the process requirements. Moldability diagrams are presented for the filling and curing steps. The criterion for selecting the amount of fiber reinforcement, injection time, catalyst level, and process temperatures in order to optimize properties and demold time is described

DESIGN STRATEGIES FOR COMPOSITE REACTION INJECTION MOLDING AND RESIN TRANSFER MOLDING.

We have presented some design suggestions for the CRIM and RTM process. The approach is by the use of moldability diagrams from which it is possible to define a set of conditions necessary to meet the process requirements. Diagrams were presented for the filling and curing steps. The conditions adopted in the process should fall inside both the filling and curing process windows. The design strategy presented should be considered as an initial stage in the definition of the process; control and optimization will require deeper understanding of the basic concepts of the operation

Process parameters estimation for structural reaction injection molding and resin transfer molding

Some design strategies for structural reaction injection molding (S-RIM) and resin transfer molding (RTM) are presented. Our approach makes use of moldability diagrams to define the parameters necessary to meet the process requirements. Moldability diagrams are presented for the filling and curing steps. The criterion for selecting the amount of fiber reinforcement, injection time, catalyst level, and process temperatures in order to optimize properties and demold time is described

DESIGN STRATEGIES FOR COMPOSITE REACTION INJECTION MOLDING AND RESIN TRANSFER MOLDING.

We have presented some design suggestions for the CRIM and RTM process. The approach is by the use of moldability diagrams from which it is possible to define a set of conditions necessary to meet the process requirements. Diagrams were presented for the filling and curing steps. The conditions adopted in the process should fall inside both the filling and curing process windows. The design strategy presented should be considered as an initial stage in the definition of the process; control and optimization will require deeper understanding of the basic concepts of the operation

“Comparison of methods to measure yield stress of concentrated surfactants.”

International audienc

Explaining the abnormally high flow activation energy of thermoplastic polyurethanes

The rheological properties of a thermoplastic polyurethane (TPU) were studied at small and large deformation via three different types of rheometry: dynamic shear, capillary, and torque (an instrumented batch mixer). The effect of degradation during TPU processing on the melt viscosity was investigated and several factors, such as temperature, time, shear stress, and flow type that may affect the degradation were studied. Apparent activation energy of flow (Ea) was determined to be 328 kJ/mol, much larger than expected. A simple model was derived to describe the relationship of molecular weight and thermal dissociation of urethane linkages. Contributions of flow and the degradation reaction of TPU to overall activation energy were found to be additive: Ea = E? + 1.7?Hdeg. True activation energy of flow (E?) was estimated to be 144 kJ/mol. While the high apparent flow activation energies in dynamic shear and capillary rheometry can be explained by simple thermal degradation, melt viscosities interpreted from the instrumented batch mixer showed a much lower apparent activation energy (186 kJ/mol). This low value may be due to a combination of effects: errors in the relation between viscosity and mixer torque for TPU, side reactions resulting from air exposure, high stress level during the melting, and extensional stresses. � 2003 Elsevier Science Ltd. All rights reserved

Block copolymer based pressure sensitive adhesives modified with PPO for increased service temperatures

Higher service temperature pressure sensitive adhesives were formulated from poly(styrene-b-isoprene-b-styrene) (SIS) block copolymer blended with low molecular weight midblock and endblock associating resins. The aliphatic midblock resin was WingTack 95(R) and the aromatic endblock resin was a polyphenylene ether, PPO. In even small amounts (< 3%) the PPO raised the service temperature of the adhesive, as measured by elevated temperature holding power (lap shear) tests. The formulations were also examined with transmission electron microscopy (TEM), small angle X-ray scattering (SAXS), dynamic mechanical analysis (DMA), and 180 degrees peel strength tests. A tentative ternary phase diagram for SIS/WingTack 95(R)/PPO was constructed and a basic understanding of structure/property relationships for this PSA system was accomplished. The large improvements in the elevated temperature holding power tests correlated with increases in the polystyrene microphase glass transition and order-disorder transition