Dimensional stability in water

Nylon 11 properties and uses Chemical and hydrocarbon resistance Thermal stability Dimensional stability in water... 

Soluble, containing sulfonic acid benzimidazole (SPBI) Sulfonated poly(ether ether ketone) (SPEEK) Dimensional stability in water at 80 C). Proton conductivity and lEC = 55 mS/cm 2010 57... 

Spruce meal and beech blocks were modified by using a mixture of perfluoroalkyl ethanol and MDI. Improved dimensional stability and water repellency were reported (Engonga etal., 1999). In order to avoid the handling problems associated with the use of most isocyanates, the generation of isocyanates within the wood by thermal rearrangement of acyl azides has been studied (Gdrardin etal., 1995) (Figure 4.8). This is potentially a... 

It is of interest that veneer-faced low-density particleboards made from acetylated veneers and acetylated core particles showed excellent dimensional stability in both liquid water and humidity tests and were resistant to attack by fungi in an 8-week soil block test [57]. Furthermore, during the 150-day bending-creep test, the totally acetylated boards showed no strength or weight loss during exposure to T. palustris. 

The high inflammability and relatively poor chemical resistance of celluloid severely restrict its use in industrial applications. Consequently the material is used because of its desirable characteristics, which include rigidity, dimensional stability, low water absorption, reasonable toughness, after-shrinkage around inserts, and ability of forming highly attractive colored sheeting. Today the principal outlets of celluloid are knife handles, table-tennis balls, and spectacle frames. Celluloid is marketed as Xylonite (BX Plastics Ltd.) in UK. 

Polyvinyl chloride fibers with improved thermal dimensional stability in boiling water can be attained by the use of a PVC, rich in syndiotacticity, and by blending with postchlorinated PVC. Further, it is possible to prepare fiber from PVC grafted with polyacrylonitrile, which shows a softening temperature much higher than 100°C. 

Most of grafted and branched sulfonated hydrocarbon PEMs have lower water uptake values as compared to other sulfonated hydrocarbon PEMs, so they exhibit great dimensional stability. In the case of the lEC values below 1.3 mequiv. g", their proton conductivities are relatively lower than other PEMs. However, when the lEC values are over 1.3 mequiv. g", their proton conductivities increase drastically to very high values (0.1-0.2 S cm" at 25°C). This behavior indicates that flexible side chains containing sulfonic acid groups help with the formation of water channels for... 

Butyrate, propionate, and acetate are rated in that order in dimensional stability in relation to the effects of water absorption and plasticizers. The materials are slow burning, although self-extinguishing forms of acetate are available. Special formulations of butyrate and propionate are serviceable outdoors for long periods. Acetate is generally considered unsuitable for outdoor uses. From an application standpoint. 

Modified PPE resins are especially noted for their outstanding hydroljdic stability. They have no hydrolyzable bonds. Their low water absorption rates— both at room temperature and at elevated temperatures—callow the retention of properties and dimensional stability in the presence of water, high-humidity, and even steam environments. In addition, modified PPE resins are generally unaffected by a wide variety of aqueous solutions, detergents, acids, and bases. 

Coarse calcium carbonate with a broad particle size distribution, based on chalk, limestone or marble, or dolomite with an average particle size of approximately 15 pm, is the main filler used in PVC floor tiles. Price is the main specification but control of colour and of levels of coarse particles is needed. It is used as an extender at 200-450 phr. To give extra dimensional stability, reduced water pick-up, and green or hot strength during calendering and extrusion of the carpet high aspect ratio platy particles are used with the calcium carbonate. Stabilisation systems have to be modified to allow for the extra reactivity of the silicate surface. 

In the Nissan Be-1 of 1986, PPO-PA alloy injection mouldings were used for the front wings and front and rear aprons. They survived on-line painting and oven temperatures of 150-160°C. Other manufacturers, in the USA, Italy and France, have since adopted PPO/PA wings for small and medium volume variants, e.g., the Renault Clio, shown in Fig. 5.7. This material is claimed to combine the dimensional stability, low water absorption and flat temperature curve of PPO with the chemical and temperature resistance and good melt flow of nylon. 

Dentures continue to be an important and major market for plastics. Use is made of acrylics (PMMAs) that includes full dentures, partial dentures, teeth, denture reliners, fillings and miscellaneous uses. PMMAs provide strength, exceptional optical properties, low water absorption and solubility, and excellent dimensional stability. In the past plastics used included nitrocellulose, phenol-formaldehyde, and vinyls as denture base materials. Results, however, were not satisfactory because these plastics did not have the proper requisites of dental plastics. Since then, PMMAs have kept their lead as the most useful dental plastics, although many new plastics have appeared and others are being tested. 

The aromatic ether bonds in PPE result in good hydrolytic stability. Because polystyrene also has no hydrolysable groups, PPE/SB blends feature high hydrolysis resistance. The polymer structure of theses blends also results in low water absorption. A typical value at room temperature is 0.2 wt.-% equilibrium concentration. This value increases to 0.3 or 0.4 wt.-% at 100 °C. These values are very low for engineering thermoplastics and contribute to excellent dimensional stability in moist surroundings. Its excellent hydrolysis resistance and low water absorption are the main reason for the increasing use of PPE/SB blends in environmental engineering applications. 

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