Anti-plasticization

Some commercial, linear (thermoplastic) polymers produce blends with lignin and lignin derivatives that fail to result in phase separation on macroscopic scale. Polyblends with lignin derivatives sometimes resemble plasticized or anti-plasticized materials. The greatest contribution lignin can make to thermoplastic systems is that of modulus and this is the same as that which lignin makes to the amorphous component of wood. 

For many years, it has been known that a small quantity of plasticizer acts as an anti plasticizer for polyvinyl chloride (PVC). During a recent search for effective plasticizers for polycarbonate, W. J. Jackson and J. R. Caldwell found several groups of compounds which acted as antiplasticizers. They increased the tensile modulus and strength and reduced the elongation of polycarbonate films. In contrast to plasticizers, these antiplasticizers affected glass transition temperature quite differently. Their mechanism is explained by the fact that they either increase crystallinity or reduce the mobility of the polymer chain through the bulkiness of their molecules. 

Subclass B2 is formed by the so-called structural composites, in which an outspoken mechanical reinforcement is given to the polymer. Subgroup B21 consists of blends of polymers with compatible anti-plasticizers subgroups B22 are the most important the fibre-reinforced polymer systems. The two components, the polymer matrix and the reinforcing fibbers or filaments (glass, ceramic, steel, textile, etc.) perform different functions the fibrous material carries the load, while the matrix distributes the load the fibbers act as crack stoppers, the matrix as impact-energy absorber and reinforcement connector. Interfacial bonding is the crucial problem. 

The effects of plasticizers has also been studied by PAL [64, 65]. The addition of a plasticizer to polymers generally has the effect of lowering the Tg, however in some cases an anti-plasticization can occur. Borek et al [65] have shown that the fraction of free volume in PVC polymers could be fit with a fourth order polynomial as a function of plasticizer concentration. The decrease in th Tg with increasing amount of plasticizer is attributed to this increase in the free volume of the polymers. 

Plasticizers have a marked effect on T. One would normally expect that the plasticized polymer would nave a lower strength, hardness, and modulus than the unplasticized material. Actually incorporation of small amounts of a plasticizer such as di(2-ethylhexyl) phthalate (OOP) causes an increase in these values. At the 10-15% level of plasticizer. X-ray diffraction studies and IR analyses show an increase in the amount of crystallinity, probably due to an ordering of polymer chains. This result is the so-called "anti-plasticizer effect" and is dependent on the type of plasticizer. As the amount of plasticizer is increased, however, these properties (tensile strength and modulus) do decrease as shown in Figure 17. The effect on T as a result of increasing levels of DOP plasticizer is shown in Frgure 18. 

The concentration of API in a solid solution formulation is typically evaluated to understand the effect of dmg loading on solid solution properties such as propensity for phase instability. The addition of some APIs directly influences properties critical to melt extrusion process design and development. For example, APIs influence melt rheology as plasticizers, anti-plasticizers, or fillers. 

Polycarbonate appears to an almost unique extent to be subject to an anti-plasticizing effect on the addition of low molecular weight compounds. It is reported that the derivatives of l,l-bis(4-hydroxyphenyl)-2,2-propane operate in this context by tightly filling the free volume between the polymer molecules. Charge-transfer complexes , for example tetracyanoethylene-A-stilbene s, antiplasticizing action has been explained in terms of aandyff relaxations. ... 

Short, H. Dow Chief Says Firms Must Beware of Anti-Plastics Efforts. Plastics News, p. 5, Oct. 16, 1989. 

Anti-plasticizers are added to rigidify polymers, and may be bulky molecules that disperse in a polymer, or sticky molecules that induce attractive interactions between the additive and polymer. For instance, see Dasmahapatra, A. K. Nanavati, H. Kumaraswamy, G. J. Chem. Phys. 2009,13I, 074905, and references therein. 

Low molar mass liquids often have a strong Tg-depressive effect. They are commonly denoted plasticizers. Polyvinylchloride (PVC) is one of the most frequently plasticized polymers (Fig. 5.12). Polar and hygroscopic polymers such as polyamides absorb water with a plasticizing effect on the polymer. Plasticization causes a depression in Tg. It is an interesting fact that small amounts of plasticizer may result in a stiffer material at temperatures below the depressed Tg. This effect is referred to as anti-plasticization and is caused by strong inter-molececular interaction between the polymer and... 

At lower additions of plasticizer (up to 10 phr), the expected softening behaviour is reversed and the compound increases in hardness and Tg. This anti-plasticization has been explained by increased crystallinity facilitated by plasticizer. 

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