The performance of the composites is determined on the basis of the interface bonding of the

Polyvinyl chloride (PVC) is one of the most commonly used thermoplastic materials in cables and wires for electrical insulation. PVC has very good-to-excellent electrical and mechanical properties which make it suitable for use as an electrical insulating material in many domestic and industrial electrical insulation applications. Mica-filled PVC composites may become the cost-effective substitutes for other types of cable and wire compositions with their improved properties. In this study, water ground mica samples of different particle sizes, surface areas, and concentrations were used for fabrication of PVC composites with and without its surface treatment. Haake Rheochord 9000 compounder using roller-type blades was used for the fabrication of different PVC test composites. Melt-compounded composite was compression molded for making sheets. Mechanical and electrical properties were determined using these test sheets. Mechanical properties such as Young’s modulus, stiffness, and shore hardness increased with increase in mica concentration, whereas tensile strength and elongation at break values are found to decrease with increase in mica concentration. Dielectric properties also increase with mica loading. Morphological studies revealed that there was good adhesion and dispersion of the mica in the PVC composite. It was revealed that mechanical and electrical properties were marginally improved with the use of silane-treated mica.

Weld-Line in an injection molded part develops when two or more melt fronts are converged together. The weld-line is unavoidable when the design is complex where two melt flow fronts are mating each other head-to-head, this mating area is mechanically weak compared to other portions of the modeled part. The decrease in strength in the weld-line area can be attributed to several factors like molecular diffusion, fiber orientation effect, unoptimized process conditions, surface tension effect, internal residual stresses, etc. The strength of the weld-line area can be increased by optimizing injection molding process parameters like melt temperature, injection speed, packing pressure, changing gate type and location, etc. The present work focuses on studying the effect of packing pressure on strength of stagnation weld-line. This has been examined with experimental testing and scanning electron micrographs of the fractured surface on the weld-line and without weld-line specimens. The special injection mold is designed and fabricated to produce plaques having stagnation weld-line. The plaques are prepared out of 30% glass-filled Polyamide 6 material. The four sets of plaques are produced by changing the magnitude of packing pressure equal to 60% of filling pressure, with increment of 20% up to 120% of filling pressure. The tensile test specimens are machined on these plaques for two different angular orientations and testing is conducted as per ISO 527-2. The results demonstrated that, without weld-line specimens, the tensile modulus, stress at break marginally increases with an increase in packing pressure, and strain at break decreases with an increase in packing pressure. However, for specimens with stagnation weld-lines, both the tensile modulus and stress at break are observed to be 42% of without weld-lines samples for minimum packing pressure. The results obtained are evident from stress-strain graphs and scanning electron micrographs.

In an injection molding process, a weld-line forms when two flow fronts meet each other. Weld-line is a weak area which reduces the strength of the part locally. For multiple gate and complex part, molding weld-lines are unavoidable, therefore mechanical behavior of the weld-line needs to be predicted. This paper presents the effect of weld-lines on tensile properties of glass fibers reinforced polyamide-6 composite. An injection molding plaque tool has been designed and manufactured with the inputs from mold flow simulation software. The gating system is designed in such a way that the angle between two flow fronts is as minimum as possible, which theoretically gives the lowest strength at weld locations. The plaques are manufactured with BASF material Ultramid B3WG6 grade (glass filled 30%) which is a widely used engineering plastic material. Test specimens have been cut on a plaque for various angular positions. Experimental evaluation for tensile testing, tensile modulus, and stressstrain behavior for specimens with and without weld-line at different angular positions was evaluated as per ISO 527-2 standards. It has been established that the weld line significantly influences the tensile properties of the part. The presence of a weld line results in a significant decrease in the tensile strength of the part. Experimental results show approximately 58% reduction in tensile modulus and 49% reduction in stress at break values in specimen with weld-lines as compared to specimen without weld-lines.

In the injection-molded parts, prediction of accurate warpage at initial level becomes mandatory to avoid iterative work of mold modifications. Simulation teams of many organizations are using existing commercial programs for process simulations. Material models in existing simulation technologies are having certain limitations and assumptions, which can regularly result in up to 50% variation of warpage results as compared to the actual physical warpage measurement. The commonly used Moldflow simulation model, for example, ignores temperature-dependent mechanical properties and the stress relaxation spectrum for viscoelastic materials. These assumptions affect the accuracy of the warpage prediction results significantly. To decrease these kinds of variations, BASF extended its Ultrasim® tool which is based on integrative simulation technology. Recently, a newly developed thermomechanical material model with temperature-dependent nonlinear mechanical properties and stress relaxation behavior was added in the Ultrasim. This model has been used in this work to consider the complete transient description of the warpage, which starts at packing phase of the part inside the mold, followed by actual cooling and ejection. In this article, unreinforced semicrystalline polybutylene terephthalate polymer material (Ultradur® B4520) is considered for warpage correlational study. The accuracy of the warpage prediction is compared between the integrative simulation approach, existing warpage simulation method, and the actual experimental inspection results. The result exhibits that the accuracy of the integrative simulation (Ultrasim)-based warpage simulation is relatively better than existing simulation technologies and closer to the actual measurement.