Novel approach to characterize the cross‐linking effect of liquid silicone rubber via cavity pressure analysis during injection molding

Weißer, Dennis F.; Mayer, Dennis; Schmid, Johannes; Deckert, Matthias H.

doi:10.1002/app.53381

Cited by 3 publications

(1 citation statement)

References 10 publications

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“…Among the commonly utilized coupling agents for modification, polythiosilane [27][28][29] stands out, encompassing compounds such as bis [3-(triethoxysilyl) propyl] tetrasulfide (Si69), bis [3-(triethoxysilyl) propyl] disulfide and γ-mercaptopropyl trimethoxysilane. During the vulcanization process, the sulfur atoms present in polythiosilane participate in cross-linking reactions with the polymer chain [30,31]. Among these compounds, Si69 is a widely acclaimed polysulfide silane coupling agent.…”

Section: Introductionmentioning

confidence: 99%

Preparation of Hydrophobic Modified Silica with Si69 and Its Reinforcing Mechanical Properties in Natural Rubber

You,

Jin

2024

Materials

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The inherent large number of hydroxyl groups of silica poses strong hydrophilicity, resulting in poor dispersibility in the natural rubber matrix. Here, the silica’s surface was hydrophobically modified with [3-(triethoxysiliconyl) propyl] tetrasulfide (Si69) to improve the dispersibility and reinforce the mechanical properties of silica/natural rubber composites. The structure and morphology of modified silica were characterized by Fourier infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), X-ray electron spectroscopy (XPS), nuclear magnetic resonance spectroscopy and the contact angle. Further, the mechanical properties, dynamic mechanical properties and morphology of silica/natural rubber composites were studied with a universal electronic tension machine, dynamic thermal mechanical properties analyzer (DMA) and scanning electron microscope (SEM). The experimental results show that the Si69 was successfully grafted onto the surface of silica, thereby significantly improving the water contact angle (a 158.6% increase) and enhancing the mechanical properties of modified silica/natural rubber composites.

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Section: Introductionmentioning

confidence: 99%

Preparation of Hydrophobic Modified Silica with Si69 and Its Reinforcing Mechanical Properties in Natural Rubber

You,

Jin

2024

Materials

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Processing recycled silicone powder in liquid silicone rubber injection molding and its influence on mechanical properties

Mayer,

Heienbrock,

Weißer

et al. 2024

Polymer Engineering & Sci

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Liquid silicone rubber (LSR) is characterized by a wide range of advantageous properties and is therefore used in many branches and industries. However, the material is difficult to recycle due to the non‐reversible cross‐linking reaction. A promising approach to recycle the already cross‐linked (post‐industrial) waste is the mechanical recycling of LSR via grinding and addition of the powder as filler in virgin material. This research focused on the processing of such LSR‐powder‐compounds via injection molding and the influence of the powder content on mechanical properties. Compounds of virgin LSR and ambient ground powder were prepared and injection molded. Both the processability and the mechanical properties were analyzed. Compounds of up to 40 wt% powder content could be processed with standard injection molding machine equipment without any noticeable issues. The results show a similar compression set for the virgin as for the recycled compounds. Hardness decreases slightly but constantly. Tensile strength and elongation at break are at similar levels for all powder added compounds and drop only by 16.6% and 12.6% compared with the virgin LSR. The results are promising and should be the basis for further and more detailed investigations to industrialize the mechanical recycling of LSR.Highlights Processing on standard injection molding machine with standard parameters. Up to 40 wt% recycled silicone powder content. Using recycled silicone particles has no effect on compression set. Tensile strength and elongation at break decrease only by 16.6% and 12.6%.

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Effects of varying mixing ratios of components A and B on optical liquid silicone rubber

Mayer,

Heienbrock,

Weißer

et al. 2024

Polymer Engineering & Sci

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The processing of optical liquid silicone rubber (LSR) formulations is associated with significant quality issues and high rejection rates. Often, the quality issues can be attributed to deviations in LSR dosing. To address these issues, specific mixing ratios of components A and B that deviate from the standard 1:1 ratio were intentionally created. These mixtures were characterized via differential scanning calorimetry, rheometer, and Fourier‐transform infrared spectroscopy. The mixtures were then processed via injection molding and mechanical properties such as shrinkage, density, hardness, and tensile properties were determined and analyzed. The results show that deviating mixing ratios for optical LSR have a significant influence on processing in terms of shifts in cross‐linking temperature and exothermic energy released, viscosity, and cavity pressure, as well as on the final component properties in terms of varying shrinkage, density, hardness, tensile strength, and elongation at break. This study shows that even small deviations have a major influence and should therefore be avoided. The requirements for the accuracy of the dosing system with regard to the mixing ratio must therefore be very high. In practice, such deviations in the mixing ratios are most likely to be detected in geometry via shrinkage, hardness, or tensile properties.Highlights More component A leads to faster but less dense cross‐linking Component B can be characterized by Fourier‐transform infrared spectroscopy via Si–H bending band at 905 cm−1. More component B leads to higher shrinkage, density, hardness, and strength. Deviations in the mixing ratio must be avoided as they lead to drastic changes. A general shift of the mixing ratio in favor of component B is less dramatic.

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Novel approach to characterize the cross‐linking effect of liquid silicone rubber via cavity pressure analysis during injection molding

Cited by 3 publications

References 10 publications

Preparation of Hydrophobic Modified Silica with Si69 and Its Reinforcing Mechanical Properties in Natural Rubber

Preparation of Hydrophobic Modified Silica with Si69 and Its Reinforcing Mechanical Properties in Natural Rubber

Processing recycled silicone powder in liquid silicone rubber injection molding and its influence on mechanical properties

Effects of varying mixing ratios of components A and B on optical liquid silicone rubber

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