Polypropylene applications medical

The launch of new resins being rare, progress on materials intended for medical applications is by way of formulation, alloys and modifications of existing resins. Thus, new radiation-stable polypropylene grades are available for the manufacture of cups, boxes, baskets, mixers, etc. that are radiation sterilized. And polyesters with better environmental stress cracking resistance are extending their potenti in the area of medical testing. 

A very original application is the use of insoluble, polymeric Gd(III)-chelates as coating materials e.g., on the polypropylene catheters used for medical purposes (97). To poly(styrene-maleic acid) copolymer (SMA), HEDTA was conjugated and the Gd(III) ions were complexed by the resulting polymer, forming SMA-HEDTA-Gd(III). As a variation, the citric acid-HEDTA-SMA polymer was synthesized and used for chelating the Gd(III)ions, forming SMA-HEDTA-citric acid-Gd(III). The Gd(III) contents were 3.75 and... 

LDPE), polypropylene (PP), poly(vinyl chloride) (PVC), and polyethylene tere-phthalate (PET) [48], completely new areas of application are preferred in which biodegradability is required for admission, such as applications in the medical field [50, 51]. The reason for this is obvious. When new materials enter the market, they are in competition with aheady established materials. In the case of PUB, due to its temperature stability, a competition with poly(olefin)s arises for all applications in which biodegradabUity is not required by law (Fig. 12). 

PHAs can consist of a diverse set of repeating unit structures and have been studied intensely because the physical properties of these biopolyesters can be similar to petrochemical-derived plastics such as polypropylene (see Table 1). These biologically produced polyesters have already found application as bulk commodity plastics, fishing lines, and for medical use. PHAs have also attracted much attention as biodegradable polymers that can be produced from biorenewable resources. Many excellent reviews on the in vivo or in vitro synthesis of PHAs and their properties and applications exist, underlining the importance of this class of polymers [2, 6, 7, 12, 26-32]. 

Substitute for Conventional Vulcanized Rubbers, For this application, the products are processed by techniques and equipment developed for conventional thermoplastics, ie, injection molding, extrusion, etc. The S—B—S and S—EB—S polymers are preferred (small amounts of S—EP—S are also used). To obtain a satisfactory balance of properties, they must be compounded with oils, fillers, or other polymers compounding reduces costs. Compounding ingredients and their effects on properties are given in Table 8. Oils with high aromatic content should be avoided because they plasticize the polystyrene domains. Polystyrene is often used as an ingredient in S—B—S-based compounds it makes the products harder and improves their processibility. In S—EB—S-based compounds, crystalline polyolefins such as polypropylene and polyethylene are preferred. Some work has been reported on blends of liquid polysiloxanes with S—EB—S block copolymers. The products are primarily intended for medical and pharmaceutical-type applications and hardnesses as low as 5 on the Shore A scale have been reported (53). 

Hollow membrane fibers are required for many medical application, e.g. for disposable dialysis. Such fibers are made by usmg an appropriate fiber spinning technique with a special inlet in the center of the spinneret through which the fiber core forming medium (liquid or gas) is injected. The membrane material may be made by melt-spinning, chemical activated spinning or phase separation. The thin wall (15-500 xm thickness) acts as a semi-permeable membrane. Commonly, such fibers are made of cellulose-based membrane materials such as cellulose nitrate, or polyacrylonitrile, polymethylmethacrylate, polyamide and polypropylene (van Stone, 1985). 

Several other common industrial polymers are also used in biomedical applications [51]. Because of its low cost and easy processibility, polyethylene is frequently used in the production of catheters. High-density polyethylene is used to produce hip prostheses, where durability of the polymer is critical. Polypropylene, which has a low density and high chemical resistance, is frequently employed in syringe bodies, external prostheses, and other non-implanted medical applications. Polystyrene is used routinely in the production of tissue culture dishes, where dimensional stability and transparency are important. Styrene-butadiene copolymers or acrylonitrile-butadiene-styrene copolymers are used to produce opaque, molded items for perfusion, dialysis, syringe connections, and catheters. 

Polypropylene accounted for about half of the nonwoven products in industrial uses in 2001. Its share in ropes and nets was 55-60%, and 70-80% in civil construction, where polyester claimed 20-24%. In automotive applications, polypropylene shared 26-30%, nylon almost 50%, and polyester about 20%. Polypropylene contributed to over 86% of agricultural nonwoven, 100% of packaging cloth, 85% of sanitary items, and 64-70% of medical applications. The world consumption of industrial nonwoven products was 1.329 MT in 2000. Polypropylene topped all synthetic fibers with a share of over 40% in this market segment. 

There is a demand for more powerful polymers like for example PEEK [103, 107, 111], which enables new application areas in the automobile industry and medical fields, as shown in Fig. 81 and underlines the increasing potential of SLS-technologies. Because of this EOS GmbH recently presented a high temperature system, EOSINT P 800, along with PEEK HP3 for SLS. There is a further interest in qualification of bulk polymers like polypropylene [100]. 3D Systems Inc. recently presented DuraForm PP 100 for SLS. Further more there is an interest in some technical polymers like Polyoxymethylene [112]. 

Polyethylene and polypropylene are ubiquitous commodity plastics found in applications varying from household items such as grocery bags, containers, toys and appliance housings, to high-tech products such as engineering plastics, automotive parts, medical appliances and even prosthetic implants. They can be either amorphous or highly crystalline, and behave as thermoplastics, thermoplastic elastomers or thermosets. 

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