Advantages over Rubber

Rubber can be formulated to meet most of the properties of polyurethanes. This is a complex capital and labor-intensive procedure. In most applications more than one property is needed, and polyurethanes provide many of these properties at one time. Rubbers that have the same or better properties than polyurethanes are detailed below. 

Resilience Load bearing Bonding to metal Compression set Electrical Impact resistance Abrasion resistance Tear resistance Cut growth Radiation resistance Weather resistance Oxidation Ozone resistance Grease and oil Water resistance 

Polyurethane is superior to all Natural, chloroprene, SBR, and nitrile Silicone and fluoroelastomers Natural, SBR, and silicone rubbers Natural and SBR 

Natural, chloroprene, SBR, and nitrile Natural rubber Natural rubber Polyurethane best 

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Hydrogenated nitrile rubbers were introduced in the mid-1980s as Therban by Bayer. The initial grade had an acrylonitrile content of only 17% instead of approx. 34% in conventional NBR. Whilst non-sulphur-curing systems such as the use of peroxides with triallyl cyanurate or isocyanurate are necessary, the saturated rubber has a number of advantages over NBR. These include improved... 

Thermoplastic elastomers have now been available for over 30 years and the writer recalls organising a conference on these materials in 1969. In spite of considerable publicity since that time these materials still only comprise about 5-10% of the rubber market (equivalent to about 1-2% of total plastics consumption). It is important to appreciate that simply being a thermoplastic material (and hence being processed and reprocessed like a thermoplastic plastics material) is not enough to ensure widespread application. Crucially the material must have acceptable properties for a potential end-use and at a finished product price advantageous over other materials. 

TPEs from blends of rubber and plastics constitute an important category of TPEs. These can be prepared either by the melt mixing of plastics and rubbers in an internal mixer or by solvent casting from a suitable solvent. The commonly used plastics and rubbers include polypropylene (PP), polyethylene (PE), polystyrene (PS), nylon, ethylene propylene diene monomer rubber (EPDM), natural rubber (NR), butyl rubber, nitrile rubber, etc. TPEs from blends of rubbers and plastics have certain typical advantages over the other TPEs. In this case, the required properties can easily be achieved by the proper selection of rubbers and plastics and by the proper change in their ratios. The overall performance of the resultant TPEs can be improved by changing the phase structure and crystallinity of plastics and also by the proper incorporation of suitable fillers, crosslinkers, and interfacial agents. 

Thermoplastic elastomers are materials that have the properties of vulcanized rubbers but can be processed by techniques associated with thermoplastics. The commercial importance of TPEs is due to their superior processing properties and economic advantages over conventional rubbers and plastics. TPEs from rubber-plastic blends became important because they combine the superior processability of thermoplastics and the... 

Plastics, such as PE, PP, polystyrene (PS), polyester, and nylon, etc., and elastomers such as natural rubber, EPDM, butyl rubber, NR, and styrene butadiene rubber (SBR), etc., are usually used as blend components in making thermoplastic elastomers. Such blends have certain advantages over the other type of TPEs. The desired properties are achieved by suitable elasto-mers/plastic selection and their proportion in the blend. 

Acrylated rubber These are based on styrene butadiene and have become commercially available only relatively recently. They are manufactured in several grades but most have the advantage over other materials in this class of being based on white spirit solvent rather than the stronger and more obnoxious xylol. In other respects, they are similar to chlorinated rubber and cost approximately the same, although they are easier to airless spray and the dried film contains less pores. They are considered to have superior weather resistance to chlorinated rubber and vinyl. 

A modified type of natural mbber which has many processing advantages over normal sheet and crepe rubbers. It shows reduced shrinkage, reduced die swell and much better retention of dimensions especially in complicated extrusions. It is made by adding a quantity of vulcanised latex to normal latex before coagulating. See PA 80. 

There is one use to which levulinic acid can immediately be put. We have found that its sodium salt has ideal properties for an antifreeze agent. It has definite advantages over ethylene glycol for this purpose. It is a solid and is therefore more easily marketed than the liquid glycol. It is less corrosive to the iron parts of internal combustion engines than is tap water itself and has no detrimental effect on the rubber connections used in engines. 

Polyurethanes have several advantages over competing material in the materials field. The major items of competition are metal, other plastics, and rubbers. Ceramics offer some competition to urethanes. Each of the above groups of materials, including polyurethanes, requires its own design adjustments for successful use in any application. 

Thermoplastic tri-block copolymers are interesting since they possess novel properties different from those of the homo- or copolymers. The thermoplastic elastomers have many of the physical properties of rubbers, i.e., softness, resilience, and flexibility. The unique properties of this kind of copolymer are due to the microphase separation of the hard crystalline domains dispersed in a continuous amorphous matrix (Fig. 6). Such phase morphology provides a physical network of flexible chains cross-linked by crystalline microdomains. The advantages over natural vulcanized rubbers are that thermoplastic elastomers are readily soluble in an appropriate solvent and can be processed as thermoplastics [109],... 

Membrane materials used are polysulfone, polystyrene, Teflon, and various rubbers. This type of separation possesses many advantages over other types of gas separation, e.g., mild operating conditions, lower energy consumption, low capital cost, and economic operation at both low and high flow rates. 

Tiquid rubbers are polymeric products used primarily as adhesives, sealants, castable rubbers, and rocket propellant binders. The name liquid rubber comes from the properties of flowing at room temperature and curing to rubbery networks. These materials offer advantages over conventional elastomers in their ease of handling and processing as they can be readily pumped and mixed in low power (relative to normal rubber) equipment with resultant savings. 

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