Textile materials, especially yarns formed from polymers such as polyester during deformation, have viscoelastic properties, namely a combination of elastic and viscous properties. Several studies have been conducted to model viscoelastic on textile materials, especially yarns. In this study, modelling is done by fitting data through experiments which are then modelled with a theory of the modification of the Maxwell model as a reference in making predictions through the data fitting method. The results of the data fitting prediction in the form of exponential curves have a regression value that approaches the experimental curve (R 2 = 0.999 and 0.999).

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Metal coatings are starting to be widely used as a way to prevent metals from corroding. In addition to preventing corrosion, metal coatings have been developed to thicken metals, increase hardness, wear resistance, and corrosion resistance. Characterization of the materials used using SEM, and XRD. The SEM characterization results show a crystal shape similar to a pyramid. The increasing coating time will increase the crystal size with the preferred plane orientation direction is [111] with the largest crystal size in the experiment with a time of 4.5 h which is 55.44 nm using the Williamson-Hall method.

Tofu industry is an industry dominated by small-scale businesses with limited capital. In terms of location, this business is also very spread throughout Indonesia. One of them is the Harapan Maju (HS) tofu industry in Cimanggis, Depok, West Java. This industry still uses the traditional method by disposing of waste into water bodies. Tofu liquid waste has the characteristics of containing high organic matter and the levels of BOD, COD, TDS are quite high, and and the pH value is low so that if it is directly discharged into the river it can pollute the environment. Therefore, bentonite and bagasse activated carbon are used to treat the waste water of the Harapan Maju tofu industry so that it is safe to be discharged into water bodies. Bentonite has a good ability to absorb organic matter and binds relatively small solids in water. Meanwhile, bagasse activated carbon functions as a purifier and absorbs heavy metals in wastewater. The process carried out is the absorption process or the process of separating solids from the fluid by passing the fluid through a filter medium or septum, where solids will be left in the medium. With this simple technology, it will be very effective when applied to the tofu industrial wastewater treatment, so that the waste that is disposed of will not disturb the ecosystem of water bodies. Before testing the BOD value was 714 ppm, TDS 1129 ppm, COD 1152 ppm and the pH of the wastewater was 4 . After testing, the BOD values were 142.8 ppm, TDS 407 ppm, COD 195.84 ppm and pH 6.

Cementing process was not good can be caused by the poor planning of cement slurry carried out in the laboratory. Poor cementing certainly cannot meet the expectations and goals of the cementing process. The purpose of this study was to select the right and optimal cement composition by testing sodium lignosulfonate retarder additives for thickening time and compressive strength. The methodology used in this study was laboratory testing using class G cement. The addition of sodium lignosulfonate additive in this class G cement was obtained the highest thickening time value at a concentration of 1.5% temperature 150 ° F for 24 hours test result.