Polypropylene heat deflection temperature

Table 8.4 shows that substantial gains can be obtained by filling crystalline polymers but amoiphous polymers are not much affected by reinforcement. Also, particulate fillers are substantially less effective than fibrous fillers. Glass fiber is the most useful filler in this application. Figure 8.55 shows the effect of two grades of particulate fillers on the heat deflection temperature of polypropylene." Small changes are obseiwed at smaller additions followed by a rapid increase in HDT above a 30% filler content. The particle size has only small difference. 

Figure 8.55. Heat deflection temperature of polypropylene containing hydrated K-Mg aluminosilicate. [Adapted, by permission, from Schott N R, Rahman M, Perez M A, J. Vinyl and Additive Technol., 1, No.l, 1995,36-40.]...

Talc - Talc is a filler made by dry or wet grinding of mineral magnesium silicate. Talc improves stiffness, dimensional stability, flexural modulus, creep resistance, flow, surface smoothness, moisture resistance, tensile strength, and wear resistance of plastics. It also increases heat deflection temperature and decreases vapor permeability. Can be used as a film antiblock agent. Used mainly in polypropylene but also in thermoplastic and unsaturated polyesters and epoxy resins at low levels. Surface-modified grades are available. 

The effect of wood species on the wood-polymer interface and on properties of WPCs has received little attention in the literature. Stark and Berger [13] evaluated the effect of ponderosa pine, loblolly pine, maple, or oak on the mechanical properties of polypropylene WPCs. In general, WPCs made with maple or oak exhibit slightly better tensile and flexural properties and heat deflection temperatures than either of the pines. Composites elaborated with coconut flber and polyurethanes have shown good results. Coconut flber acts as reinforcement and active part of the matrix system, improving the interface... 

Figure 3.116 Dissipation factor vs. frequency and temperature for Mitsubishi Engineering-Plastics lupiace AV 40—UL94 V-1 rated, heat deflection temperature (HDT) 100°C polypropylene ether, and PS blend resin.

Tcdc. Talc is a magnesium silicate mineral, often used in polypropylene to improve processing, rigidity, creep resistance, and heat deflection temperature. 

Isotactic polypropylene composites with tetra-needle-shaped zinc oxide whisker were prepared via melt blending in a twin-screw extruder. The whisker is a p-nucleating agent, which offers higher crystallization temperature, smaller sphemlites, and faster crystalhzation rate than can be obtained in neat iPP. The addition of whisker also increases heat deflection temperature and thermal degradation temperature of iPP composite. ... 

Polypropylene is a very versatile polymer. It has many properties that make it the polymer of choice for various applications (e.g., excellent chemical resistance, good mechanical properties and low cost). There are many ways in which the mechanical properties of polypropylene can be modified to suit a wide variety of end-use applications. Various fillers and reinforcements, such as glass fiber, mica, talc, and calcium carbonate, are typical ingredients that are added to polypropylene resin to attain cost-effective composite mechanical properties. Fibrous materials tend to increase both mechanical and thermal properties, such as tensile strength, flexural strength, flexural modulus, heat deflection temperature, creep resistance, and sometimes impact strength. Fillers, such as talc and calcium carbonate, are often used as extenders to produce a less-costly material. However, some improvement in stiffness and impact can be obtained with these materials. 

Since the heat deflection temperature is closely related to the stiffness of the composite, HDT increases with increased talc loading in polypropylene, as shown... 

Table 14.11 Effect of Mica Concentration on Heat Deflection Temperature of Polypropylene Homopolymer Composites...

Heat deflection temperature changes are shown in Fig. 14.4. Highest heat deflection temperatures were obtained with KMG silane treatment and by addition of an acrylic acid modified polypropylene. The 241 and 240°F heat deflection temperatures are approximately 20% higher than observed with untreated mica. 

Reinforcement of polypropylene with mica provides outstanding flexural modulus and heat deflection temperature, minimizes warpage, and gives good dimensional stability. Often, however, impact properties are decreased. A paper given to the SPE Polyolefins X Conference in 1997 (31) focused on improvement of the impact-stiffness balance of mica-reinforced polypropylene by use of additives. 

Maleic anhydride modified polypropylene consistently decreased Izod impact but provided large increases in Gardner and unnotched Izod impact. Heat deflection temperature plus tensile and flexural properties were also increased substantially. 

See Table 14.41 for formulations that give the best HDT, melt index, and mold shrinkage values. Maximum predicted heat deflection temperature, 143°C, was obtained with 40 wt% mica, 53 wt% polypropylene, and 7 wt% Unite MP-1000. 

Figure 2-21. Heat Deflection Temperature — Filament Diameter vs Strand Solids, Polypropylene ...

The heat deflection temperature of polypropylene is affected primarily by surface area (see Fig. 2-26). Therefore, the relationship of bundle size/strand solids is similar to that described previously for strand solids. 

Figure 2-26. Heat Deflection Temperature— Chopped Strand Length vs Bundle Cross-Sectional Area, Polypropylene ...

Additional data are shown in Figs. 2-19, -20, -21, -22, -23, -24, and -26 for flexural strength and heat-deflection temperatures of nylon 6/6, and Izod impact and heat deflection temperatures of polypropylene. See also par. 2-5.2 for discussion of critical fiber length. 

Polypropylene homopolymers have excellent resistance to heat, water absorption, and chemical attack, but lack dimensional stability at high temperatures and wear properties. Glass-reinforced homopolymers are only marginally superior to unreinforced systems. Glass-reinforced coupled or copolymer polypropylenes have significantly improved strengths and heat deflection temperatures. 

Mica provides similar benefits in a wide range of thermoplastic and thermoset composites including polyolefins, polyamides and styrenics. It is also reported that surface coated mica further increases tensile strength, flexural strength and modulus, and heat deflection temperature. The automobile industry is the main user of mica-filled composites, either with polypropylene or nylon as polymer matrix. Up to 40% mica loadings are used, sometimes in association with calcium carbonate, to produce various injection... 

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