LDPE, additives Fillers

Additives, Fillers and Reinforcements 283 Commonly used in LDPE, EVA and... 

The heat capacity is the amount of energy required to increase the temperature of a unit mass of material. It is commonly measured using a differential scanning calorimeter (DSC). The heat capacity depends on the resin type, additives such as fillers and blowing agents, degree of crystallinity, and temperature. A temperature scan for the resin will reveal the Tg for amorphous resins and the peak melting temperature and heat of fusion for semicrystalline resins. The heat capacities for LDPE and PS resins are shown in Fig. 4.15. 

Starch and cellulosic materials are frequently used as fillers in degradable materials. The addition of starch to LDPE in combination with a pro-oxidant increases the photooxidation rate and the formation of hydroperoxides and carbonyl groups. Starch alone does not increase the photooxidation rate. The addition of starch to LDPE increases its stability in 80°C water. Slower degradation in water is due to leaching out of the pro-oxidant. The addition of starch causes biodegradation process under soil burial conditions. Further increase in the degradation rate can be achieved by preheating polyethylene filled with starch. ... 

U.S. Pat. No. 6,632,863 [115] (by Crane Plastics Company, Timber-Tech) discloses a wood-plastic composition manufactured as feedstock pellets comprising 55-90% cellulosic material such as wood flour and wood fiber, 10-40% of polyolefin such as HDPE, LDPE, and polypropylene, and 0-35% total of additive(s), such as lubricants and inorganic fillers, such as talc and mica. 

Chem. Descrip. LDPE CAS 9002-88-4 EINECS/ELINCS 200-815-3 Uses Additive for FRP composites binder for loose particles/fibers sintering agent in ceramics, powd. metallurgy cosmetic filler for soaps/... 

Fig. 10-14. DSC relates to the effects of additives and fillers that can be used in quality control for LDPE foam.

Mica flakes embedded in a polymer and properly oriented in a plane can provide a tortuous path to vapors and liquids, similarly to the natural composites shown in Figure 1.1. Barrier properties can be imparted in blow-molded containers, packaging films, and corrosion-resistant coatings not only by mica but also by other impermeable lamellar fillers, including glass flakes, talc, and nanoclays. In blown LDPE film, the addition of 10% mica was found to reduce the oxygen permeabihty from 4.16 to 3.03 Barrer [37]. Assuming an impermeable, fully oriented lamellar filler, Eq. (8.1), [38] maybe used to predict the composite permeability. Pc, perpendicularly to the filler plane as a function of the matrix permeability, P , filler volume fraction, V(, matrix volume fraction, V , and filler aspect ratio a... 

HDPE immiscibly blends with hutyl ruhher [14] to provide improved chemical resistance, compression set and high-temperatnre mechanical properties versus nnvnlcanised hlends. LDPE and HDPE blend immiscibly with ethylene copolymers to improve environmental stress crack resistance, tonghness, filler acceptance, film tear resistance, improved flexibility and so on. In polyolefin, polybntene-1 forms miscible blends with PP [15,16]. The addition of PP to polybutene-1 increases the crystallisation rate of polyhntene-1 and would have utility as a nucleation additive. 

In 2007, Rezanejad and Kokabi developed a low density polyethylene (LDPE)/ nanoclay composite with shape memory properties [72], Although all SMPs do not necessarily rely on a two-phase structure such as that of melt processed LDPE, extrapolation from this work can be made for a wide range of SMP systems. The team used organically modified Cloisite 15A nanoclay as filler and demonstrated a 300% increase in both E and E" upon addition of up to 8% nanoclay. Although the neat polymer system had nearly 100% shape recovery, the 8% loaded sample recovered nearly 80% at pre-strains of both 50 and 100%. Recovery stress, however, was dramatically increased from 1 MPa for the neat LDPE to about 3 MPa at 50% pre-strain and above 3 MPa at 100% pre-strain. 

Either PA-6 or PA-6,66, was blended with 1-50 wt% of a PA/LDPE laminated film scrap. As a compatibilizer, either an ethylene-acrylic acid-/-alkyl acrylate, ethylene-glycidyl acrylate, allyl glycidyl ether- -alkyl acrylate, ethylene-acrylic acid (or ester)-MA, or EMA, was used. The blends could also contain inorganic fillers, other resins, elastomers, and additives. The materials had good impact and notched impact strength, combined with stiffness and toughness. They have been used for the same applications as new materials, instead of having to be downcycled [40]. 

Figure 2.16 shows the TG separation of an LDPE formulation containing a lubricant, carbon-black and inert filler using an optimised stepwise analysis mode. The percentage lubricant, polymer, carbon, and inert filler can quantitatively be determined [272]. Lever et al. [273] have shown that HRTGA gives a much cleaner resolution of mass losses than conventional TG of a polymeric derivative used as an oil additive. Also the high resolution TG analysis of DOP in vinyl plastics has been reported [229]. 

Machalkova [643] has described analysis of polymer composites and rubber blends with emphasis on separation of low-MW additives by instrumental methods. Examples refer to analysis of inorganic filler- or synthetic fibre-reinforced plastics and laminated plastic Aims using PyGC and IR. The versatility of PyGC has further been exemplified by Jones [633] as a thermovolatilisation technique for direct determination of occluded volatiles and low-MW additives in lube oil, novolac resins and HDPE, of plasticisers and vinylchloride in PVC, and of solvent residues in paints and bitumens, etc. Dicumylperoxide (DCP) in LDPE was identified through detection of three main by-products of reaction, acetophenone, a-methylstyrene and 2-phenylpropan-2-ol [633]. 

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