When the sample is heated a second time, the heat of fusion
is higher (99.A3 J/g vs.
Composite PCMs are the constituents that have the enhanced belongings like thermal conductivity, heat of fusion
, density and melting point in appraisal to single PCM like paraffin wax etc.
DSC thermogram of (a) amorphous PC 175 powder; (b) PC 175 powder after immersing in acetone for 1 min showing a melting endotherm: heat of fusion
was 22.5 J/g, degree of crystallinity was [X.sub.c] = 20.5%.
The PCM used in this store needs to be further evaluated to determine its effective melting temperature and heat of fusion
. Simple temperature measurements are insufficient, and a DSC should be used to calculate these values for technical-grade PCMs.
But since the heat of fusion
is given as an energy per unit mass of the whole sample, the presence of the filler dilutes this value in proportion to the amount of filler that is in the compound.
PCM solidifies on drop of ambient temperature giving off its latent heat of fusion
. As compared to conventional materials PCMs have the property of storing high amount of latent heat giving more heat storage capacity per unit volume.
where [DELTA][H.sub.f] is the heat of fusion
of the sample and [DELTA][H.sup.c.sub.f] (= 285 J/g) is the heat of fusion
of a 100% crystalline sample [4, 28, 30],
Tetradecane is chosen due to its freezing point being suitable for chilled water storage systems (~ 5.6[degrees]C, ~42[degrees]F), high heat of fusion
(~200kJ/kg, ~86 BTU/[lb.sub.m]), and the lack of a subcooling requirement for freezing.
The inner layer consists of 50 wt% polyethylene copolymer having a melt index less than 2g/10 min., a density less than or equal to 0.910 g/[cm.sup.3], a total heat of fusion
less than 120 J/g, and a heat of fusion
above 115[degrees]C of less than 5J/g.
Specifically, the first propylene-based elastomer comprises at least 7% by weight ethylene or non-propylene alpha-olefin units, the second propylene-based elastomer comprises less than 7% by weight ethylene or non-propylene alpha-olefin units, the first and second propylene-based elastomers each have a heat of fusion
less than 80 J/g, and the propylene-based thermoplastic polymer has a heat of fusion
greater than 80 J/g.
%, based on the total weight of the polymer component of a propy-lene elastomer having a heat of fusion
of less than 70 J/g and an isotactic triad tacticity of 50 to 99% and optionally containing units derived from a diene, the polymeric component having a density of less than 0.9 g/[cm.sup.3] and (b) from 20 to 120 phr, preferably 30 to 100 phr, most preferably 40 to 90 phr based on the total weight of the polymer component of a reinforcing filler component; and (c) a peroxide curative.
Joint quantity of heat from wax part and silicone rubber mould is heat quantity caused by temperature change and heat of fusion