Crosslinked thermoplastics

Chattopadhyay, S., Chaki, T.K., Bhowmick, A.K., Gao, G.J.P., and Bandyopadhyay, S., Structural characterization of electron-beam crosslinked thermoplastic elastomeric films from blends of polyethylene and ethylene-vinyl acetate copolymers, J. Appl. Polym. Sci., 81, 1936, 2001. 

A wide range of thermoplastic starch compounds have been claimed in recent years. Formulations of thermoplastic starch with linear, biodegradable polyesters, including polycaprolactone and PHBV,174 176 and with polyamides175 have been reported. Laminated structures have been claimed using thermoplastic starch or starch blends as one or more of the layers.175,177,178 The use of polymers latexes as components of thermoplastic starch blends has also been claimed.179 181 Blends with natural polymers are also claimed, including cellulose esters182,183 and pectin.184 A crosslinked thermoplastic material of dialdehyde starch and protein has been reported.185... 

More recently, blends of a partially crosslinked thermoplastic elastomer with 5-40 parts of a PO (viz. LLDPE, PP, EPR, or PB-1) were developed for low density, foamable alloys [Okada et al, 1998a]. The density was reduced at least by a factor of two. In the following patent 1-17 wt% of a long-chain branched PP was also added [Okada et al, 1998b]. The extmded foam was free of surface roughness caused by defoaming, was soft to the touch and showed excellent heat and weathering resistance. 

Linear or branched, that is, not crosslinked, thermoplastic materials, usually first begin to soften on heating and then on further heating (amorphous polymers) begin to flow over a rather ill-defined temperature range (see Figure 3.1). Partially crystalline plastics in general have narrow melt-... 

Features Exc. adhesion soft, clear, glossy, flexible but though films wash resist, when crosslinked thermoplastic crosslinkable Properties Opaque dens. 8.72 Ib/gal vise. 100 cps pH 8 VOC 183 g/l anionic 30% solids... 

Chem. Descrip. Aqueous dispersion of a self-crosslinking thermoplastic... 

ASTM D6338-98 Standard Classification System for Highly Crosslinked Thermoplastic Vulcanizate (HCTPVs)... 

Fig. 1 Four types of SMPs (dual-shape effect) depicted as a function of their dynamic thermomechanical behavior. Plotted is the tensile storage modulus vs temperature as measured using a smtdl oscillatory deformation at 1 Hz for (a) Cat. A-I, chemically crosslinked amorphous polymer network (7, = Tg) (b) Cat. A-II, chemically crosslinked semicrystalline polymer networks (Ttrans = 7m) (c) Cat. B-I, physically crosslinked thermoplastic with r,ra,K = 7g and (d) Cat. B-II, physically crosslinked thermoplastic (Tlrans = Tm). Taken from ref [5], Copyright 2007. Reproduced by permission of the Roytd Society of Chemistry, http //dx.doi.org/10.1039/b615954k...

Fig. 2 Schematic five types of SMPs depicted as a function of their thermal behavior. Plotted is the heat flow vs temperature as measured in a differential scanning calorimetry (DSC) experiment (a) Cat. A-1, chemically crosslinked tunorphous polymer network (Tirans = 7g) (b) Cat. A-11, chemically ciossfinked semicrystaUine polymer networks (Taims = 7m)> ( ) Cat. B-1, physically crosslinked thermoplastic with Tirans = T (d) Cat. B-11, physically crosslinked thermoplastic (Tams = I m) and (e) liquid crystalline polymer (Tlrans = T -n)...

Class 1. Non-crosslinked thermoplastic polyurethanes Step 1. Linear dihydroxy polyester or polyether + excess diisocyanate... 

Fig. 2.5. Schematic representation of the principle used for crosslinkable thermoplastic polyurethanes.

Of the available polyurethane types, the crosslinked thermoplastic polyurethane elastomers seem to be best for use in powdered form. 

EFFECT OF POST-CURE ON THE PHYSICAL PROPERTIES OF PARTIALLY CROSSLINKABLE THERMOPLASTIC POLYURETHANES ... 

Garaflex E, Crosslinked thermoplastic vinyl elastomer, AlphaGary Corp. 

Improved tensile strength Rubber crosslinker Thermoplastic rubbers Vulcanizable rubbers Rubber composites with improved impact... 

Change in important properties of crosslinking thermoplastic resins [722]... 

In the temperature range from 230 to 280 °C, which is relevant for lead-free soldering, the crystalline regions in thermoplastics will melt. In non-crosslinked plastic films, there are no sufficient bonds left to hold the material together. The crystallites in crosslinked thermoplastics also melt, but the chemical crosslinking bonds hold the macromolecule together in its amorphous zones so that they can keep their shape - even at low stiffness levels. The crosslinked film remains sufficiently strong and stable short-term up to approx. 300 °C [720]. 

Of the available polyurethane types, the virtually crosslinked thermoplastic polyurethane elastomers would seem to be best and ideally suited for supply and use in powdered form. Their uses include adhesive applications which exploit the advantages of the powder form. 

Murakami S (2004) D5rnamically crosslinked thermoplastic elastomer compositions and their moldings with good flexibility and low compression set, Jpn Kokai Tokkyo Koho JP 2004 010 770, to Mitsui Ghem Inc. 

The combination of processability and performance provided by these polymers makes them natural candidates for applications such as microelectronics laminates as well as structural and dielectric composites (2). The versatility provided by the use of phenolic feedstocks has allowed the extension of this chemistry into polyesters (i), classical photoresist chemistry (4), and thermally crosslinkable thermoplastics (5). It has also provided a method for thermally processing low molecular weight imide-containing oligomers into high molecular weight polyetherimides (d) In addition, oligomers which are useful as fluorinated lubricant fluids have been prepared (7). 

Z. Ghazali, A. F. Johnson, K. Z. Dalhlan, Radiation crosslinked thermoplastics natural rubber (TPNR) foams, Radiation Physics and Chemistry, 1999, 55, 73-79... 

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