Impact improvers

Impact energy can be further improved by the use of impact modifiers. In this approach the combination of impact improvement and fire retardant enhancing is of special interest (ref. 5). Figure 5 demonstrates this effect in ABS flame-retarded with commercial FR-1208 (octabromodiphenyl oxide) and with the proprietary FR-T6385. 

It is obvious from these data that CTBN (the carboxyl terminated butadiene-acrylonitrile copolymer) is the most effective modifier, and therefore it was selected for further study. As the concentration of the elastomer was increased to levels up to 100 parts, the impact also increased. The data in Table II show that the room temperature impact of ERL-4221 increased from 40 inch-lbs to greater than 320 inch-lbs by adding 100 phr or 33 wt % of CTBN. At very low temperatures ( —160°F) the impact of the system modified with 60 parts, or 23 wt %, of CTBN was 120 inch-lbs. These impact improvements appear to be directly proportional to the concentration of the elastomer modifier. 

This article aims to answer three key questions, namely, (1) Are there voluntary actions by the industry (2) is there recognition of this contribution by governments and, (3) how can these contributions be further encouraged and their impact improved ... 

How Can These Contributions Be Further Encouraged and Their Impact Improved ... 

By 1992, the free-world catalyst market could reach four billion dollars and the United States projection is estimated to be two billion (18). It is difficult to estimate how much of an impact improved methods for engineering improved mechanical and physical properties will have on these figures, but we can expect that all catalysts will be checked to meet the specifications of the user and the quality control program of the producer. 

Also the carbon black in the rubber particles might reduce their ability to promote ductility and impact resistance. Thus carbon black may sacrifice much of the impact improvement which the rubber originally ... 

Amount of Rubber. Generally the impact strength of rubber-modified plastics increases with an increase in rubber content. Although the impact improves, it is usually at the sacrifice of other properties such as strength, modulus, heat distortion, weather resistance, and creep. 

DMA measurements are intensively used to investigate the amorphous phase transitions of polymers. The results of DMA studies were published by authors like Schmieder and Wolf [2], Nielsen and Buchdahl [3] and Heijboer [4]. Neat polymers, but also polymer blends and polymer systems blended with fillers, plasticisers or impact improvers were investigated by DMA. An example of such an application is given for toughened polypropylene in 4.1.2. 

Polypropylene (PP) is often blended with ethylene/propylene (BP) rubbers to improve the impact resistance. This so-called toughened PP (TPP) can be a mechanically blended PP/C2C3 rubber system or an in-situ polymerised PP/C2C3 rubber system. A number of rubber parameters (like concentration, particle size, particle size distribution, crystallinity, molecular weight etc.) determine the ultimate effect of the rubber addition on the impact resistance. DMA is one of the analytical techniques often used to investigate blends of polymers with an impact improver. The determination of the relation between the area of the rubber relaxation maximum as measured by DMA and the rubber concentration is usually a first step in such an investigation. The method to determine this area and the results measured on a series of PP/C2C3 rubber blends are reported below. 

Simultaneous TSD/TMA measurement on a PVC sample with 10%wt. impact improver... 

Table 6.7 and Table 6.8 summarizes selected LIPN systems developed for two- and three-stage systems, respectively. For the latter, polymer 3 is usually a finear overcoat. Of great interest throughout are morphology and concomitant behavior. Appfications for coatings, damping, and impact improvement are discussed in many of the works. 

Ellram LM, Birou LM (Contributor). Purchasing for Bottom Line Impact Improving the Organization Through Strategic Procurement. The NAPM Professional Development Series. Vol. 4. 1995. 

Figure 10.18 shows that impact strength of plasticized PVC increases with increase in the amoimt of the plasticizer. The impact improvement is not gradnal bnt requires a certain critical concentration of the plasticizer. This critical concentration of the plasticizer depends on properties of pair polymer/plasticizer For example in plasticization of polyamide-11 ductile-brittle transition occurred at 4-6% of one plasticizer and in vicinity of 15% of another plasticizer. 

Ethylene-ethyl acrylate or butyl acrylate copolymers (E-EA or E-BA) Ester No reactivity with amine No impact improvement. Used only as codiluent... 

Discovery of isotactic PP was immediately followed by search for low-T impact improvement, initially by blending with either LDPE or elastomers, later by copolymerizing with ethylene and dienes into EPR and EPDM... 

Lubricants. Lubricants represent a broad class of materials that are used to improve the flow characteristics of plastics during processing. Besides this primary task of improving flow properties, lubricants can act as melt promoters, antiblock, antitack, and antistatic agents as well as color and impact improvers. They can be used in conjunction with metal release agents and heat stabilizers. Lubricants are widely... 

Okamoto, Y. Miyagi, H. Kakugo, M. Takahashi, K., Impact Improvement Mechanism of HIPS with Bimodal Distribution of Rubber Particle Size. Macromolecules 1991, 24, 5639-5644. 

Figure 14.6 Impact improvements in polypropylene homopolymer 30% HiMod-360 mica in Profax 6501 homopolymer. A, C, E, no additive B, 1% Struktol TR-016 D, E, 6% Unite MP-1000. (From Ref. 31.)...

Figure 6 shows the impact performance of 4 ply PE/carbon hybrids with various HP-PE/carbon ratios. The amount of HP-PE fibre within the hybrid was varied by replacing carbon plies by HP-PE plies. To obtain an optimum effect on impact improvement HP-PE plies were positioned at the opposite side of the impacted surface. Also the influence of improved adhesion of HP-PE on impact performance was investigated. As expected we see with increasing amount of HP-PE fibre an increase in impact performance. 

Extrusion-grafted functionalized polyolefin-based polymers (such as Exxon s Exxelor) - maleated or aminated - offer better polymer/flller adhesion as well as impact improvement in engineering polymers and compatibilization in blends and alloys. They function as impact modifiers, compatibilizers and adhesion... 

The observation that addition of a small amount of finely dispersed polyolefin or rubber dramatically changes the fracture behavior of PA led to blending for impact improvement of other engineering resins, viz., PET, PBT, POM, PPE, etc. Similarly, the use of acidified polymers to polyesters and polycarbonates led to a new type of polymer alloys. 

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