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Thickening Agents
Published in Heather A.E. Benson, Michael S. Roberts, Vânia Rodrigues Leite-Silva, Kenneth A. Walters, Cosmetic Formulation, 2019
Ricardo D’Agostino Garcia, Antony O’Lenick, Vânia Rodrigues Leite-Silva
Polyamide oil structuring polymers offer a broad range of functionality to personal care formulations as film formers, water repellency agents, pigment and polymeric emulsion stabilizers, structuring agents and rheology modifiers. These polymers are low colour and low odour, high-performance thermoplastic solids proven to form crystal clear, thermo-reversible gels. The products work with a range of high to low polarity oils, providing compatibility with an array of cosmetic ingredients. They also create novel formats, from clear sticks and balms to sprayable gels and emulsions with real consumer benefits.
Mechanical Effects of Cardiovascular Drugs and Devices
Published in Michel R. Labrosse, Cardiovascular Mechanics, 2018
Early-generation dilatation balloons were composed of linear low-density polyethylene (LLDPE), characterized as very flexible, large profile, and with a low pressure range. Polyethylene materials emerged later and produced less compliant balloons that can withstand higher pressures with minimal diameter change. Nylon and Pebax (polyamides) are commonly used in current clinical practice, especially for stent deployment PCI. The development of multilayer balloons resulted in more flexible, lower-profile balloons capable of dilating lesions at very high pressures. These characteristics are especially useful for dilating calcified/resistant lesions. Each company designs multilayer BDC differently and for different applications. Multilayer balloons can include one balloon inside another, as well as coextruded balloon material, where different polymers are combined in a molten state to create a single layer of material. The multiple layers serve several purposes: one is to offer lower profiles and enhanced performance, without compromising rupture strength, and another is to minimize the risk of pinholes and reduce material rupture.
Innovative industrial technology starts with iodine
Published in Tatsuo Kaiho, Iodine Made Simple, 2017
Polyamide fibers are generally known as nylon, and on account of their superior toughness, adhesiveness, and fatigue resistance, they are widely used for various industrial materials such as rubber reinforcement cords for tires, conveyor belts, transmission belts and rubber hoses, safety belts, tents, plaited cords, sewing thread, and airbags. In 2011, global production of polyamide fibers reached 6.8 million tons [36a]. Polyamides used as industrial materials are exposed to harsh environments during the processing stages of production such as heat, oxygen, and light and during use as automobile products (particularly nylon cords for tires and airbag cords). In order to prevent deterioration in these environments, various stabilizers are added.
Advances in additive manufacturing processes and their use for the fabrication of lower limb prosthetic devices
Published in Expert Review of Medical Devices, 2023
Shaurya Bhatt, Deepak Joshi, Pawan Kumar Rakesh, Anoop Kant Godiyal
Thermoplastic polymers such as polyaryletherketones have been used to fabricate spinal implants and orthopedic devices due to their temperature stability, chemical resistance, and high level of strength [37]. Polyamide is also a synthetic material widely used for the SLS process. PCL is also one of the biodegradable polymers used for the SLS process. The PCL material used for scaffold manufacturing showed that it could be a viable option for tissue engineering application to repair bone and cartilage as it provided an environment that supported cell growth [40]. Poly lactides such as PLA are also biocompatible materials produced from renewable resources and have high rigidity and strength but are brittle [37]. The strength of PLA was enhanced by introducing carbon nanotube into them. 3D-printed composite produced by polylactic acid, thermoplastic polyurethane, and graphene oxides was investigated for their compatibility in tissue scaffolds. Thermal and mechanical properties and the effect of varying printing parameters were explicitly studied. It was found that the 3D-printing process enhanced the thermal stability and to understand the effect of varying printing orientations and the effect of the addition of graphene oxide on cellular growth [41]. A correlation between the water-absorbing capability and the presence of methyl side groups in lactic acid was studied [42]. The greater water-absorbing capability was found in scaffolds with a lower ratio of lactic acid to glycolic acid.
Artificial hair implantation for hair restoration
Published in Journal of Dermatological Treatment, 2022
Aditya K. Gupta, Maanasa Venkataraman, Emma M. Quinlan
In the early days, artificial fibers consisted of synthetic fibers made of monoacrylic,polyacrylic, or polyester materials, or natural fibers, such as processed human hair (21). Manufacturers of present-day synthetic fibers (Biofibre®, Nido Z-type) state that the problems associated with earlier fibers such as non-biocompatibility, tolerability, and safety have been resolved; currently available synthetic fibers are made of polyamide material which are claimed to be inert, safe, and tolerable (21). Biofibre® medical hairs are available in 13 colors, different lengths (15, 30, or 45 cm), and various shapes (straight, wavy, and curly) (13,21). MHD® (released in 2014) is a high-density version of regular Biofibre® hairs which are implanted only in the crown area, while the lightweight regular Biofibre® hairs are used to populate the front hairline, which has thin dermal tissue (23). Besides androgenetic alopecia, the use of synthetic hair fibers has been reported in the treatment of other alopecias, for example, pharmacological, primary cicatricial (scarring alopecia due to innate hair follicle-directed causes), and secondary cicatricial (scarring alopecia due to incidental causes such as traumatic burns and surgical scars) (23,26). However, the role of artificial hair implantation in treating other types of alopecias, such as triangular temporal alopecia, has not been reported.
Selective laser sintering 3D printing – an overview of the technology and pharmaceutical applications
Published in Drug Development and Industrial Pharmacy, 2020
Naseem A. Charoo, Sogra F. Barakh Ali, Eman M. Mohamed, Mathew A. Kuttolamadom, Tanil Ozkan, Mansoor A. Khan, Ziyaur Rahman
The powder layer is usually preheated below the melting point temperature to prevent manufacturing defects such as warping and deforming in sintered parts. The heating may cause physical and chemical changes in the powder material. For instance, solid state polycondensation reduced the crystallinity of polyamide 12 powder by 6% after three recycles [42]. In another study, polyamide 12 powder was found to undergo molecular entanglement which depends on temperature and time. The high temperature and longer exposure time to high temperatures may cause the molecular chains to become larger, resulting in increase in molecular weight, decrease in fluidity, and change in mechanical and thermal properties [41]. However, pharmaceutical polymers usually degrade to smaller chain length on thermal exposure, which will dramatically change their physicochemical properties [43]. This can be prevented to a certain extent by printing in an inert gas environment. Another approach is to use a blend of used and unused powder which fulfills the thermal requirements of raw material as well as CQA of final dosage forms. Stabilizing agents such as thioethers in combination with antioxidants can also be used [11,44,45]. Alternative recycling approaches have been proposed. For example, Feng et al. recycled polyamide 12 powder after SLS into filaments for FDM and proposed it as one of the means to reduce cost and environmental impact [45]. However, this approach may not be applicable to pharmaceuticals due to adverse effect on CQAs of the dosage forms.