Performance Impacts

The constmction of the E-111 windshield shown in Eigure 8 replaced a glass—silicone laminate previously used. The all-plastic windshield has improved impact resistance so that it is birdproof to 250 m/s (33). In this instance, the scratch resistance of glass was waived to obtain the impact performance at the allowed weight. 

R. L. Morrison, "Influence of Ambient Temperature on Impact Performance of HPR Wiadshields," presented at Fifteenth Stapp Car Crash Conference, SAE 1971, pp. 603—612. 

The properties of PBT and PC resins and of a blend of these two resins are given in Table 18. The chemical resistance of crystalline PBT is reduced, but that of amorphous PC is increased. Hydrolytic stabiUty is good throughout. Impact performance is lower than that of the components. It can be improved by modifiers. A commercial example of this type of resin blend is the General Electric Xenoy resin which is used in automotive bumpers. 

Although the Izod and Charpy tests are widely used for plastics, other types of test are also popular. These include tensile impact tests and flexural plate (falling weight) tests. The latter is particularly useful in situations where the effects of flow anisotropy are being assessed. In addition, arbitrary end-product tests are widely used to provide reassurance that unforseen factors have not emerged to reduce the impact performance of the product. 

In a partially crystalline homopolymer, nylon 6, property enhancement has been achieved by blending with a poly(ethylene-co-acrylic acid) or its salt form ionomer [24]. Both additives proved to be effective impact modifiers for nylon 6. For the blends of the acid copolymer with nylon 6, maximum impact performance was obtained by addition of about 10 wt% of the modifier and the impact strength was further enhanced by increasing the acrylic acid content from 3.5 to 6%. However, blends prepared using the salt form ionomer (Sur-lyn 9950-Zn salt) instead of the acid, led to the highest impact strength, with the least reduction in tensile... 

As previously described (Chapter 2), the area under short-term stress-strain curves provides a guide to a material s toughness and impact performance (Fig. 7-6). The ability of a TP to absorb energy is a function of its strength and its ductility that tends to be inversely related. The total absorbable energy is proportional to the area within the lines drawn to the appropriate point on the curve from the axis. The material in area A is... 

One of the few disadvantages associated with nanoparticle incorporation concerns the loss of some properties. Some of the data presented have suggested that nanoclay modification of polymers such as polyamide could reduce impact performance [28]. Nanofillers are sometimes very matrix-specific. High cost of nanofillers prohibits their use. 

DfE forms partnerships with industry and other interested parties to develop information on environmental and human health impacts, performance, and cost of cleaner technologies and approaches. 

Adams, D.F. and Zimmerman, R.S. (1986). Static and impact performance of polyethylene fiber/graphite fiber hybrid composites. Allied Fibers, Petersberg, VA. 

MULTIPLE-IMPACT PERFORMANCE OF HIGH-DENSITY POLYETHYLENE FOAM... 

STYRENE-MALEIC ANHYDRIDE. A thermoplastic copolymer made by the copolymerization of styrene and maleic anhydride. Two types of polymers are available—impact-modified SMA terpolymer alloys (Cadon ) and SMA copolymers, with and without rubber impact modifiers (Dylark ). These products are distinguished by higher heat resistance than the parent styrenic and ABS families. The MA functionality also provides improved adhesion to glass fiber reinforcement systems. Recent developments include lerpolymer alloy systems with high-speed impact performance and low-temperature ductile fail characteristics required by automotive instrument panel usage. 

Diblock copolymers, especially those containing a block chemically identical to one of the blend components, are more effective than triblocks or graft copolymers. Thermodynamic calculations indicate that efficient compat-ibilisation can be achieved with multiblock copolymers [47], potentially for heterogeneous mixed blends. Miscibility of particular segments of the copolymer in one of the phases of the bend is required. Compatibilisers for blends consisting of mixtures of polyolefins are of major interest for recyclates. Random poly(ethylene-co-propylene) is an effective compatibiliser for LDPE-PP, HDPE-PP or LLDPE-PP blends. The impact performance of PE-PP was improved by the addition of very low density PE or elastomeric poly(styrene-block-(ethylene-co-butylene-l)-block styrene) triblock copolymers (SEBS) [52]. 

Description Ethylene feedstream (plus recycle ethylene) and butenes feedstream (plus recycle butenes) are introduced into the fixed-bed, metathesis reactor. The catalyst promotes reaction of ethylene and 2-butene to form propylene and simultaneously isomerizes 1-butene to 2-butene. Effluent from the metathesis reactor is fractionated to yield high-purity, polymerization-grade propylene, as well as ethylene and butenes for recycle and small byproduct streams. Due to the unique nature of the catalyst system, the mixed C4 feed stream can contain a significant amount of isobutylene without impacting performance of the OCT process. A variation of OCT—Automet Technology—can be used to generate ethylene, propylene and the comonomer—hexene-1—by metathesis of n-butenes. 

Particle size is important and, for some applications requiring good weathering and impact performance (window profile), the ultrafine milled, high whiteness, natural version is normally used. To ease dispersion, the filler is usually coated with stearic acid. Coated ultrafine and precipitated calcium carbonates are claimed also to have a positive effect on impact properties in impact modified formulations (52, 294, 462). The abrasive wear of calcium carbonate, on melt processing equipment, is not significant but increases with increasing levels (177). 

Uprating PVC compounds often involves the careful specification and addition of mineral fillers. This article discusses calcium carbonate, talc and glass fibre, taking into account their size and their shape factor. Rigidity is sensitive to the shape factor of the filler as is the dimensional stability. This study shows that glass fibre is the most efficient filler. Talc is more efficient than calcium carbonates. The impact performance is very sensitive to the particle size. Precipitated calcium carbonate is the only filler to act as an impact modifier. 12 refs. 

Brookfield, Ct., SPE, 2002, Paper 571, Session W7-Vinyl Plastics. Vinyl Composites, pp.5, CD-ROM, 012 EFFECT OF CALCIUM CARBONATE SIZE AND LOADING LEVEL ON THE IMPACT PERFORMANCE OF RIGID PVC COMPOUNDS CONTAINING VARYING AMOUNTS OF ACRYLIC IMPACT MODIFIER Bryant W S Wiebking H E Specialty Minerals Inc. 

Brighton, 20th-22nd April 1999, p.200-9 IMPACT PERFORMANCE OF WOOD-GRAIN FOIL COATED PVC-U WINDOW PROFILES, AND THE EFFECT OF ARTIFICIAL WEATHERING AND ABRASION Newman C J Gardiner D UK,Building Research Establishment (IOM Communications Ltd. BPF)... 

The impact behaviour of pure and impact modified PVC is studied in terms of the ductile-brittle transition. These transitions show an Arrhenius dependence on temperature related to the beta motions of the PVC matrix. A model based on Eyring theory is proposed. Beyond its theoretical interest, the model predicts the impact performance of PVC at various temperature and impact modifier contents. 6 refs. 

Fig. 13 Influence of the cooling rate on the impact performance of /S-modified PP (MFR 0.3 dg min-1). The specimens were compression molded and tested at 1.5 ms-1. The arrows indicate the temperature at which the ductile-brittle transition occurred...

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