HDPE, additives Solvents

Applications Caceres et al. [114] compared various methods for extraction of Tinuvin 770 and Chimas-sorb 944 from HDPE pellets, namely room temperature diffusion in CHC13 (20 % extraction), ultrasonica-tion (20% extraction), Soxtec extraction with DCM (nonsolvent) (50 % extraction), dissolution (dichloroben-zene)/precipitation (2-propanol) (65-70% recovery) and boiling under reflux with toluene (solvent) at 160 °C (95 % extraction). By changing conditions (nature of solvent, T, t) similar comparisons do not have much added value. Table 3.6 compares the results of reflux extraction and MAE for additives in LDPE [115]. 

The initial solvent of choice for the polyolefin treatment train is xylene. Much research has b n published on the dissolution and precipitation behavior of polyethylene and polypropylene in xylene [34-39], In addition, researchers at RPI have shown that xylene can be used to separate PP from HDPE in a solvent process [33], Although it is apparent that xylene is acceptable for this treatment, additional research aimed at separating these specific polymers may yield a more suitable solvent. 

HDPE(-g-MA) (80) mechanical properties / SEM / selective solvent extraction / DSC / simultaneous addition of PA + PE + MA + radical initiator 1993, 1992... 

The process can combine conventional glass fiber roving, aramid, or carbon fiber tows with TPs, most commonly polyethylene terephthalate (PET) and nylon (polyamide/PA). Other plastics used include polyphenylene sulphide (PPS), styrene-maleic anhydride (SMA), high-density polyethylene (HDPE), and polypropylene (PP). The TPs can take the form of pellets, chips, chunks, or shreds, and as the process uses hot-melt injection, no solvents or two-part systems are involved. Additives such as colorants and fillers can be used as required. 

PA-11 (20) or PA-6/ HDPE-g-MA (80) Internal mixer or TSE at 210 °C/torque rheometry/mechanical properties/SEM/selective solvent extraction/DSC/simultaneous addition of PA + PE -t MA + radical initiator Lambla and Seadan 1992, 1993... 

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]. 

In addition to its biodegradability and biocompatibility, PPDX is a semicrystalline poly(ester-alt-ether) with a Tg at approximately -10 ° C and Tm at around 110 ° C. PPDX has shown to be tougher than PLAs and even HDPE with a tensile strength close to 50 MPa for an ultimate elongation ranging from 500 to 600% (Figure 17). PPDX is poorly soluble expect in exotic solvents such as hexafluoroisopropyl, 1,1,2,2-tetrachloroethane, dimethyl sulfoxide, N,N-dimethyl formaldehyde, and 1,2-dichloro ethane. ... 

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