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Published in Mark J. Kaiser, Arno de Klerk, James H. Gary, Glenn E. Hwerk, Petroleum Refining, 2019
Mark J. Kaiser, Arno de Klerk, James H. Gary, Glenn E. Hwerk
Paraffin wax is derived from petroleum distillates, and microcrystalline wax is derived from petroleum residua. Paraffin wax, commonly known as slack wax, is manufactured from neutral lube base oils and find application in candles, waxed paper, and as a solid camping stove fuel. Microcrystalline wax, or micro wax, is derived from heavy feedstocks such as bright stock, and have a higher viscosity and melting point than paraffin wax. Micro wax is often used as a base for chewing gum and as a coating for cheese wheels. Petrolatum wax (mineral jelly or petroleum jelly) is a mix of paraffin wax, white mineral oil, and micro wax that is semi-solid at room temperature. Vaseline, a trademarked product since 1870, is one of the most well-known petroleum jelly products.
Pharmaceuticals
Published in James G. Speight, Handbook of Petrochemical Processes, 2019
Paraffin wax is a white or colorless soft, solid wax that is composed of a complex mixture of hydrocarbons with the following general properties: (i) nonreactive, (ii) nontoxic, (iii) water barrier, and (iv) colorless. Paraffin wax is characterized by a clearly defined crystal structure and has the tendency to be hard and brittle with a melting point typically in the range 50°C–70°C (122°F–158°F). On a more specific basis, petroleum wax is of two general types: (i) paraffin wax in petroleum distillates and (ii) microcrystalline wax in petroleum residua. The melting point of wax is not directly related to its boiling point, because waxes contain hydrocarbons of different chemical nature. Nevertheless, waxes are graded according to their melting point and oil content.
Extended-Release Dosage Forms Prepared Using Twin-Screw Extrusion
Published in Isaac Ghebre-Sellassie, Charles Martin, Feng Zhang, James DiNunzio, Pharmaceutical Extrusion Technology, 2018
De Brabander applied the melt extrusion process to prepare extended-release ibuprofen tablets using microcrystalline wax. A binary mixture of microcrystalline waxes and ibuprofen was melt extruded. The extrudates were then milled and compressed into tablets. The release of ibuprofen was accelerated by incorporating starch with different swelling and disintegration properties (De Brabander et al. 2000). Microcrystalline wax is composed of a mixture of straight-chain and branched saturated alkanes obtained from petroleum. Depending on the chain length and degree of branch, various microcrystalline waxes of different melting points are available. Slower ibuprofen release was observed for wax with a higher melting point (De Brabander et al. 2000).
Research progress of new nanocomposite pour point depressant: a mini-review
Published in Petroleum Science and Technology, 2021
Huili Zhang, Hailin Yu, Yu Gao, Wei Jiang, Jinjun Deng
Waxy crude oil is an important fossil fuel resource, widely distributed around the world, and has been developed and utilized in China, India, Egypt, the North Sea, and other regions for decades (Wu et al. 2005). These fluids contain a large amount of petroleum wax (usually ≥5 wt%), which makes the extraction, processing, and transportation of crude oil more complicated (Chen, Tang, and Zhang 2011). Petroleum wax can be divided into two different types: macrocrystalline paraffin and microcrystalline paraffin (Leube et al. 2000). The macrocrystalline wax is mainly composed of low molecular weight linear alkanes (C16–C40) and is usually crystallized as a needle. Microcrystalline wax is mainly composed of high molecular weight isomeralkanes and cycloalkanes. Because of the large number of isomers, microcrystalline waxes usually precipitated as small amorphous particles and did not exhibit a significant crystalline state (Chen et al. 2014). When waxy crude oil is below the wax precipitation temperature (WAT), paraffin wax will gain from the crude oil, which will affect pipeline transportation. The deposition phenomenon will reduce the effective pipeline diameter, and in severe cases will cause the pipeline to be completely blocked, thus adversely affecting the operation of the pipeline.
Study on structure control and pour point depression mechanism of comb-type copolymers
Published in Petroleum Science and Technology, 2021
Zihao Huang, Xin Pu, Jiawen Hu, Jin Gu, Jichang Liu
Pipeline transportation can significantly reduce transportation costs compared to shipping. However, the high-wax content of crude oil is serious hindrances preventing the safety of pipeline transportation (Pedersen and Ronningsen 2003). Crude oil is a complex mixture, which is mainly composed of waxes, asphaltenes, and resins. The formation of net-like or cage-like structure caused by wax precipitation is the main reason for the high-wax crude oil. Petroleum wax can be divided into macro-crystalline and micro-crystalline wax. Generally, macro-crystalline waxes which are mainly composed of low molecular weight alkanes (C16–C40) will precipitate to form needlelike or flaky crystals at low temperature (Das et al. 2017). In contrast, micro-crystalline waxes that are composed of iso-alkanes and cyclo-alkanes with high molecular weight have the ability to combine with more oil than macro-crystalline waxes (Wang et al. 2019). Owing to a great deal of isomer permutations, micro-crystalline waxes precipitate to form small crystals or amorphous particles without obvious crystalline state at low temperature (Wang et al. 2020). When the temperature of crude oil reduces to the wax appearance temperature (WAT), the wax crystals begin to precipitate, overlap, and eventually form a three-dimensional network structure. As a result, the effective transport area of the pipeline was reduced, leading to a reduction in the efficiency of crude oil extraction and transportation (Zhao et al. 2018). Hence, in order to ensure the normal production and pipeline transportation of crude oil, it is crucial to reduce the formation and growth of wax crystal to improve the low-temperature fluidity of crude oil (Li et al. 2018).
Development of hybrid pattern material for investment casting process: an experimental investigation on improvement in pattern characteristics
Published in Materials and Manufacturing Processes, 2021
Harun et al.[9] investigated the characteristics of H-shape (both solid and hollow) acrylonitrile butadiene styrene (ABS) pattern prepared by using the FDM process. As compared to the solid pattern, the hollow pattern resulted in lesser dimensional variability and collapsibility. Moreover, the mold developed by using hollow pattern was free from cracks at all temperatures. However, the distortion was higher in hollow patterns as compared to the solid pattern. No significant difference was observed in SR of both the patterns. Based on the above-discussed literature, it can be summarized that the conventional wax pattern has the problems of excessive shrinkage and poor surface finish. The polymeric pattern has a good surface finish, but at the same time, it has the problem of distortion. Ice pattern is very difficult to handle because it requires a controlled environment for shell preparation. Therefore, in order to overcome the problems of shrinkage and surface finish, there is a need to develop a pattern material which can provide the lowest possible shrinkage as well as a good surface finish. With this objective, in the present investigation, a novel coconut oil-based hybrid (COBH) pattern material was introduced for the first time by mixing coconut oil with microcrystalline wax. The coconut oil has a lower viscosity (i.e., better fluidity) and low ash content as compared to conventional wax. Therefore, it may improve the surface finish of the pattern and it may also reduce the gas porosity defects. Moreover, the coconut oil remains in a mushy state even at room temperature due to which it can be easily removed from the shell during dewaxing without shell cracking. Another reason to select coconut oil as a pattern material was that it has a density similar to the waxes. But, coconut oil is a soft material due to which it may not provide adequate hardness to the pattern which may causes distortion of the pattern. To improve the hardness of the pattern, microcrystalline wax was added to coconut oil. Microcrystalline wax is an amorphous material and the literature reveals that amorphous structure produces less internal stresses during solidification as compared to a crystalline structure.[10] Owing to the amorphous structure, it has very less volumetric change during solidification, thereby reducing the stresses induced during solidification.[11] The COBH blend has a lesser melting range (42°C-47°C) as compared to the conventional wax blend (65°C-71°C) which may help in retaining the dimensional accuracy of the pattern.