THE EFFECT OF POROSITY ON GLASS TRANSITION MEASUREMENT

Figures & data

Table 1. Glass Transition Measurements of Synthetic Polyethylene Polymer in Porous Form by DMTA and Powder Form by DSC and Controlled Strain Rheometer (n=3)

Synthetic Polymer Sample	DMTA Tp (°C)±% COV	DSC Tm′ (°C)±% COV	Rheometer Tm″ (°C)±% COV
Coarse Polymer	104.9±3.4^a	66.7±3.9^a	59.80±3.9^a
Medium Polymer	90.9±2.1^b	61.6±3.3^a	59.97±2.8^a
Fine Polymer	83.3±2.8^c	64.1±3.7^a	60.73±1.9^a

T_p means that T_g range was determined by tan delta peak.

T_m′ means that T_g range was determined by the midpoint heat capacity change.

T_m″ means that T_g range was determined by the midpoint of G′ values as a function of temperature.

COV is the coefficient of variation.

Different letters within a column indicate significant differences (p=0.05).

Figure 1. Representative two peaks tan δ vs. temperature plot obtained with DMTA.

Figure 2. Representative DSC scan.

Figure 3. Representative G′ versus temperature plot obtained with controlled strain rheometry.

Table 2. Porosity and Apparent Density Measurements of Porous Extruded Samples (n=3)

Pore Modifying RH	Porosity (unitless)±% COV	Apparent Density (g/cm^3)±% COV
LiCl-11%	0.862±4.8^a	0.053±3.9^a
KAc-22%	0.839±3.8^a	0.063±3.5^b
NaCl-75%	0.818±5.4^a	0.084±3.2^c
KCl-85%	0.699±5.2^a,b	0.105±3.1^d
K2SO4-98%	0.355±4.2^a,b,c	0.194±3.1^e

COV is coefficient of variation.

Different letters within a column indicate significant differences (p=0.05).

Table 3. Glass Transition Measurements of the Extruded Samples in Porous Form and Tablet Form by DMTA and Powder Form by DSC and Controlled Strain Rheometer (n=3)

	Porous Specimen DMTA Tp (°C)±% COV
Pore Modifying RH	Peak 1	Peak 2	Tablet Specimen DMTA Tp (°C)±% COV	Powder DSC Tm′ (°C)±% COV	Powder Rheometer Tm″ (°C)±% COV
LiCl-11%	46.1±8.9^a	89.3±8.3^a	17.8±12.9^a	26.42±12.9^a	37.9±16.3^a
KAc-22%	44.5±9.9^a	85.1±7.4^a	17.1±13.4^a	31.24±13.8^a	33.5±15.8^a
NaCl-75%	41.7±9.8^a	82.5±7.4^a	16.4±10.4^a	30.86±12.6^a	34.2±16.9^a
KCl-85%	44.4±7.4^a	75.6±5.2^a,b	15.5±5.8^a	33.58±10.4^a	38.2±12.6^a
K2SO4-98%	42.4±8.5^a	66.9±6.6^a,b,c	17.9±10.6^a	29.59±8.1^a	33.5±13.1^a

T_p means that T_g range was determined by tan delta peak.

T_m′ means that T_g range was determined by the midpoint heat capacity change.

T_m″ means that T_g range was determined by the midpoint of G′ values as a function of temperature.

COV is coefficient of variation.

Different letters within a column indicate significant differences (p=0.05).

Figure 4. Representative DMTA plots including both tan δ and E′ versus temperature curves.

Table 4. Average Final Moisture Contents and Average Moisture Loss by the Extrudate Samples During Testing (n=3)

Pore Modifying RH	Final Moisture Content (%)±SD	DMTA Moisture Loss (%)±SD
LiCl-11%	10.3±2.1^a	9.1±1.5^a
KAc-22%	9.9±1.9^a	8.2±1.4^a
NaCl-75%	10.9±2.0^a	9.3±1.7^a
KCl-85%	11.1±2.1^a	9.9±1.7^a
K2SO4-98%	10.8±1.9^a	7.0±1.6^a

SD is standard deviation.

Different letters within a column indicate significant differences (p=0.05).