Plastic incompatibility

Figure 6.6 Plastic incompatibility. Showing at A and B that symmetric boundaries are plastically compatible, whereas asymmetric ones at C and D are not.

Synthetic gums Carbomer 934 Anionic 0.5-1 Soluble in water 5-11 Plastic Incompatible with cationic polymers, strong acids and high levels of electrolytes... 

CHEMICAL PROPERTIES polymerizes to a plastic incompatible with oxidizing agents, copper, aluminum, and peroxides reacts with alcohols and halides FP (-15 °C) AT (519 °C) LFL/UFL (6.5%, 15.5%)... 

EXPLOSION and FIRE CONCERNS combustible liquid and vapor NFPA rating Health 1, Flammability 2, Reactivity 0 explosive vapor-air mixtures may be formed above 48°C (118°F) flashback along vapor trail may occur closed containers may explode when heated sensitive to static discharge contact with strong oxidizers may cause fire may form explosive peroxides attacks some forms of plastics incompatible with strong acids, alkalies, and oxidizers hazardous decomposition products include carbon monoxide and carbon dioxide use alcohol-resistant foam, dry chemical or carbon dioxide for firefighting purposes. 

Stress also plays a role in localized corrosion owing to its connection with elastic-plastic incompatibilities between particles and matrices. For example, it has been proposed that stress or strain creates a crevice between a hard particle and a soft matrix where a special chemistry may subsequently develop. Stress effects are more complicated in many observed cases of SCC emanating from pits in complex alloys where the oxide film has already been ruptured. Because these driving forces are not well understood, the concept of accumulation of damage under stressed conditions cannot be used as a basis for quantitative life prediction. 

The recycling of complex, heterogeneous mixtures of polymers is an important challenge for the recycling of post-consumer plastics. Incompatibility and degradation render secondary materials with poor mechanical properties. 

Water solubility of each higher MW phthalate ester plasticizer for PVC is exceedingly low as is water extractability. Water typically removes plasticizer from flexible PVC sheet by invading the plastic and causing some plasticizer incompatibility. In theory, plasticizer on the surface of the film or sheet can be removed even without being dissolved in the water. [5] However, in a static test, plasticizer extractabilities from flexible PVC sheet by plain water are always somewhat lower than (but in the same relative direction as) plasticizer extractabilities by soapy water. 

Goextrusions. In coextmsion, two or more thermoplastic resin melts are extruded simultaneously from the same die. Coextmsion permits an intimate layering in precisely the quantities required to function. Incompatible plastic materials are bonded with thermoplastic adhesive layers. Coextmded films may be made by extmsion-blowing or slot-casting of two, three, or more layers, eg, AB or ABA. Slot-casting is capable of combining up to 11 layers. 

Because high oxygen-barrier plastics are incompatible with other thermoplastics, extmdable adhesives must be extmded between the layers. Scrap can be included within the multilayer stmcture, provided an extmdable adhesive is incorporated. 

Similarly, the random introduction by copolymerization of stericaHy incompatible repeating unit B into chains of crystalline A reduces the crystalline melting point and degree of crystallinity. If is reduced to T, crystals cannot form. Isotactic polypropylene and linear polyethylene homopolymers are each highly crystalline plastics. However, a random 65% ethylene—35% propylene copolymer of the two, poly(ethylene- (9-prop5lene) is a completely amorphous ethylene—propylene mbber (EPR). On the other hand, block copolymers of the two, poly(ethylene- -prop5iene) of the same overall composition, are highly crystalline. X-ray studies of these materials reveal both the polyethylene lattice and the isotactic polypropylene lattice, as the different blocks crystallize in thek own lattices. 

Copolymers are typically manufactured using weU-mixed continuous-stirred tank reactor (cstr) processes, where the lack of composition drift does not cause loss of transparency. SAN copolymers prepared in batch or continuous plug-flow processes, on the other hand, are typically hazy on account of composition drift. SAN copolymers with as Httle as 4% by wt difference in acrylonitrile composition are immiscible (44). SAN is extremely incompatible with PS as Httle as 50 ppm of PS contamination in SAN causes haze. Copolymers with over 30 wt % acrylonitrile are available and have good barrier properties. If the acrylonitrile content of the copolymer is increased to >40 wt %, the copolymer becomes ductile. These copolymers also constitute the rigid matrix phase of the ABS engineering plastics. 

Goal Tar. In roofing, coal tar is used as mopping bitumen in between 15 and 20% of the BUR roofs installed. Coal-tar pitch and asphalt are considered incompatible and should not be mixed. If mixed, an oily exudate is formed that plasticizes the bitumen, and the mixture remains soft and does not weather well. For this reason, if coal tar is used in BUR systems the felts must be coal-tar saturated. There has been some success using asphalt-coated fiber-glass mat felts with coal-tar pitch. However, this has only been done for a limited number of years so the actual compatibiHty is not fully known. 

The polarity of the polyethers makes them incompatible with hydrocarbon-type plasticizers, which tend to bleed. Effective plasticizers are ethers such as di(butoxyethoxyethyl)formal [143-29-3] (Thiokors TP-90B), esters such as di(2-ethylhexyl) phthalate [117-81-7] dioctyl phthalate (DOP), polyesters such as Paraplex G50 (Rohm and Haas), and ether—esters such as di(butoxyethoxyethyl) adipate [114-17-3] (Thiokol s TP-95). The lower mol wt plasticizers, DOP, TP-90B, and TP-95 improve vulcanizate low temperature performance. The polymeric plasticizers maintain higher temperature and long-term aging properties. Epoxidized plasticizers should be avoided because they interfere with vulcanization. 

In general, fully compatible resin are desirable. However, there are many applications where borderline compatibility is tolerated, and even in some cases, borderline compatibility or controlled incompatibility may enhance tack in adhesive systems. On the other hand, a resin with a borderline compatibility in combination with an oil or plasticizer in an adhesive formulation, will result in phase separation and therefore the migration of the oil or plasticizer to the adhesive surface is favoured. 

The development of new polymer alloys has caused a lot of excitement in recent years but in fact the concept has been around for a long time. Indeed one of the major commercial successes of today, ABS, is in fact an alloy of acrylonitrile, butadiene and styrene. The principle of alloying plastics is similar to that of alloying metals - to achieve in one material the advantages possessed by several others. The recent increased interest and activity in the field of polymer alloys has occurred as a result of several new factors. One is the development of more sophisticated techniques for combining plastics which were previously considered to be incompatible. Another is the keen competition for a share of new market areas such as automobile bumpers, body panels etc. These applications call for combinations of properties not previously available in a single plastic and it has been found that it is less expensive to combine existing plastics than to develop a new monomer on which to base the new plastic. 

Incompatible wastes requiring separate decontamination stations (metal drum vs. plastic drum)... 

Unlike incompatible heterogeneous blends of elastomer-elastomer, elastomer-plastic, and plastic-plastic, the reactively processed heterogeneous blends are expected to develop a variable extent of chemical interaction. For this reason the material properties, interfacial properties, and phase morphology of reactively processed blends would differ significantly from heterogeneous mixtures. 

The TLCP used was KU 9231 produced by Bayer AG, Germany. The matrix material was an engineering plastic polyethersulfone (PES) manufactured by Jilin University, China. In an earlier article [11] we reported that KU 9231 was incompatible with the PES. 

Biguanides Chlorhexidine Severe pH7-8 Avoid contact with eyes and mucous membranes Sensitivity may develop Incompatible with soap and anionic detergents Inactivated by hard water, some materials and plastic... 

The main classes of plasticizers for polymeric ISEs are defined by now and comprise lipophilic esters and ethers [90], The regular plasticizer content in polymeric membranes is up to 66% and its influence on the membrane properties cannot be neglected. Compatibility with the membrane polymer is an obvious prerequisite, but other plasticizer parameters must be taken into account, with polarity and lipophilicity as the most important ones. The nature of the plasticizer influences sensor selectivity and detection limits, but often the reasons are not straightforward. The specific solvation of ions by the plasticizer may influence the apparent ion-ionophore complex formation constants, as these may vary in different matrices. Ion-pair formation constants also depend on the solvent polarity, but in polymeric membranes such correlations are rather qualitative. Insufficient plasticizer lipophilicity may cause its leaching, which is especially undesired for in-vivo measurements, for microelectrodes and sensors working under flow conditions. Extension of plasticizer alkyl chains in order to enhance lipophilicity is only a partial problem solution, as it may lead to membrane component incompatibility. The concept of plasticizer-free membranes with active compounds, covalently attached to the polymer, has been intensively studied in recent years [91]. 

Addition of a dioctyl phthalate plasticizer (DOP) increases flammability and incompatability of PVC with flame retardants. 

INCOMPATIBILITY DS2 is a corrosive material and because of its content, it is incompatible with some metals (e.g., cadmium, tin and zinc) some plastics (e.g., Lexan, cellulose acetate, polyvinyl chloride, Mylar, and acrylic) some paints wool leather oxidizing materials (e.g., Super Tropical Bleach or High Test Hypochlorite) and acids. 

CORROSION - Recommended materials - Prohibited materials INCOMPATIBLE WITH - Water - Heat transfer fluids - Metals - Plastic materials, others... ... 

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